civetweb/src/civetweb.c

// Copyright (c) 2004-2013 Sergey Lyubka
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#if defined(_WIN32)
#if !defined(_CRT_SECURE_NO_WARNINGS)
#define _CRT_SECURE_NO_WARNINGS // Disable deprecation warning in VS2005
#endif
#else
#ifdef __linux__
#define _XOPEN_SOURCE 600     // For flockfile() on Linux
#endif
#define _LARGEFILE_SOURCE     // Enable 64-bit file offsets
#define __STDC_FORMAT_MACROS  // <inttypes.h> wants this for C++
#define __STDC_LIMIT_MACROS   // C++ wants that for INT64_MAX
#endif

#if defined (_MSC_VER)
// 'type cast' : conversion from 'int' to 'HANDLE' of greater size
#pragma warning (disable : 4306 )
// conditional expression is constant: introduced by FD_SET(..)
#pragma warning (disable : 4127)
// non-constant aggregate initializer: issued due to missing C99 support
#pragma warning (disable : 4204)
#endif

// Disable WIN32_LEAN_AND_MEAN.
// This makes windows.h always include winsock2.h
#if defined(WIN32_LEAN_AND_MEAN) && (_MSC_VER <= 1400)
#undef WIN32_LEAN_AND_MEAN
#endif

#if defined USE_IPV6 && defined(_WIN32)
#include <ws2tcpip.h>
#endif

#if defined(__SYMBIAN32__)
#define NO_SSL // SSL is not supported
#define NO_CGI // CGI is not supported
#define PATH_MAX FILENAME_MAX
#endif // __SYMBIAN32__

#ifndef IGNORE_UNUSED_RESULT
#define IGNORE_UNUSED_RESULT(a) (void)((a) && 1)
#endif

#ifndef _WIN32_WCE // Some ANSI #includes are not available on Windows CE
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#endif // !_WIN32_WCE

#include <time.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>

#define MAX_WORKER_THREADS 1024

#if defined(_WIN32) && !defined(__SYMBIAN32__) // Windows specific
#if defined(_MSC_VER) && _MSC_VER <= 1400
#undef _WIN32_WINNT
#define _WIN32_WINNT 0x0400 // To make it link in VS2005
#endif
#include <windows.h>

#ifndef PATH_MAX
#define PATH_MAX MAX_PATH
#endif

#ifndef _WIN32_WCE
#include <process.h>
#include <direct.h>
#include <io.h>
#else // _WIN32_WCE
#define NO_CGI // WinCE has no pipes

typedef long off_t;

#define errno   GetLastError()
#define strerror(x)  _ultoa(x, (char *) _alloca(sizeof(x) *3 ), 10)
#endif // _WIN32_WCE

#define MAKEUQUAD(lo, hi) ((uint64_t)(((uint32_t)(lo)) | \
      ((uint64_t)((uint32_t)(hi))) << 32))
#define RATE_DIFF 10000000 // 100 nsecs
#define EPOCH_DIFF MAKEUQUAD(0xd53e8000, 0x019db1de)
#define SYS2UNIX_TIME(lo, hi) \
  (time_t) ((MAKEUQUAD((lo), (hi)) - EPOCH_DIFF) / RATE_DIFF)

// Visual Studio 6 does not know __func__ or __FUNCTION__
// The rest of MS compilers use __FUNCTION__, not C99 __func__
// Also use _strtoui64 on modern M$ compilers
#if defined(_MSC_VER) && _MSC_VER < 1300
#define STRX(x) #x
#define STR(x) STRX(x)
#define __func__ __FILE__ ":" STR(__LINE__)
#define strtoull(x, y, z) (unsigned __int64) _atoi64(x)
#define strtoll(x, y, z) _atoi64(x)
#else
#define __func__  __FUNCTION__
#define strtoull(x, y, z) _strtoui64(x, y, z)
#define strtoll(x, y, z) _strtoi64(x, y, z)
#endif // _MSC_VER

#define ERRNO   GetLastError()
#define NO_SOCKLEN_T
#define SSL_LIB   "ssleay32.dll"
#define CRYPTO_LIB  "libeay32.dll"
#define O_NONBLOCK  0
#if !defined(EWOULDBLOCK)
#define EWOULDBLOCK  WSAEWOULDBLOCK
#endif // !EWOULDBLOCK
#define _POSIX_
#define INT64_FMT  "I64d"

#define WINCDECL __cdecl
#define SHUT_WR 1
#define snprintf _snprintf
#define vsnprintf _vsnprintf
#define mg_sleep(x) Sleep(x)

#define pipe(x) _pipe(x, MG_BUF_LEN, _O_BINARY)
#ifndef popen
#define popen(x, y) _popen(x, y)
#endif
#ifndef pclose
#define pclose(x) _pclose(x)
#endif
#define close(x) _close(x)
#define dlsym(x,y) GetProcAddress((HINSTANCE) (x), (y))
#define RTLD_LAZY  0
#define fseeko(x, y, z) _lseeki64(_fileno(x), (y), (z))
#define fdopen(x, y) _fdopen((x), (y))
#define write(x, y, z) _write((x), (y), (unsigned) z)
#define read(x, y, z) _read((x), (y), (unsigned) z)
#define flockfile(x) EnterCriticalSection(&global_log_file_lock)
#define funlockfile(x) LeaveCriticalSection(&global_log_file_lock)
#define sleep(x) Sleep((x) * 1000)
#define rmdir(x) _rmdir(x)

#if !defined(va_copy)
#define va_copy(x, y) x = y
#endif // !va_copy MINGW #defines va_copy

#if !defined(fileno)
#define fileno(x) _fileno(x)
#endif // !fileno MINGW #defines fileno

typedef HANDLE pthread_mutex_t;
typedef HANDLE pthread_t;
typedef struct {
    CRITICAL_SECTION threadIdSec;
    int waitingthreadcount;     // The amount of worker threads.
    pthread_t *waitingthreadids;// The worker thread IDs.
} pthread_cond_t;

#define pid_t HANDLE // MINGW typedefs pid_t to int. Using #define here.

static int pthread_mutex_lock(pthread_mutex_t *);
static int pthread_mutex_unlock(pthread_mutex_t *);
static void to_unicode(const char *path, wchar_t *wbuf, size_t wbuf_len);
struct file;
static char *mg_fgets(char *buf, size_t size, struct file *filep, char **p);

#if defined(HAVE_STDINT)
#include <stdint.h>
#else
typedef unsigned int  uint32_t;
typedef unsigned short  uint16_t;
typedef unsigned __int64 uint64_t;
typedef __int64   int64_t;
#define INT64_MAX  9223372036854775807
#endif // HAVE_STDINT

// POSIX dirent interface
struct dirent {
    char d_name[PATH_MAX];
};

typedef struct DIR {
    HANDLE   handle;
    WIN32_FIND_DATAW info;
    struct dirent  result;
} DIR;

#if !defined(USE_IPV6) && defined(_WIN32)
#ifndef HAVE_POLL
struct pollfd {
    SOCKET fd;
    short events;
    short revents;
};
#define POLLIN 1
#endif
#endif

// Mark required libraries
#ifdef _MSC_VER
#pragma comment(lib, "Ws2_32.lib")
#endif

#else    // UNIX  specific
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <stdint.h>
#include <inttypes.h>
#include <netdb.h>

#include <pwd.h>
#include <unistd.h>
#include <dirent.h>
#if !defined(NO_SSL_DL) && !defined(NO_SSL)
#include <dlfcn.h>
#endif
#include <pthread.h>
#if defined(__MACH__)
#define SSL_LIB   "libssl.dylib"
#define CRYPTO_LIB  "libcrypto.dylib"
#else
#if !defined(SSL_LIB)
#define SSL_LIB   "libssl.so"
#endif
#if !defined(CRYPTO_LIB)
#define CRYPTO_LIB  "libcrypto.so"
#endif
#endif
#ifndef O_BINARY
#define O_BINARY  0
#endif // O_BINARY
#define closesocket(a) close(a)
#define mg_mkdir(x, y) mkdir(x, y)
#define mg_remove(x) remove(x)
#define mg_sleep(x) usleep((x) * 1000)
#define ERRNO errno
#define INVALID_SOCKET (-1)
#define INT64_FMT PRId64
typedef int SOCKET;
#define WINCDECL

#endif // End of Windows and UNIX specific includes

#include "civetweb.h"

#define CIVETWEB_VERSION "1.5"
#define PASSWORDS_FILE_NAME ".htpasswd"
#define CGI_ENVIRONMENT_SIZE 4096
#define MAX_CGI_ENVIR_VARS 64
#define MG_BUF_LEN 8192
#ifndef MAX_REQUEST_SIZE
#define MAX_REQUEST_SIZE 16384
#endif
#define ARRAY_SIZE(array) (sizeof(array) / sizeof(array[0]))

#ifdef _WIN32
static CRITICAL_SECTION global_log_file_lock;
static DWORD pthread_self(void)
{
    return GetCurrentThreadId();
}
#endif // _WIN32

#define MD5_STATIC static
#include "md5.inl"

#ifdef DEBUG_TRACE
#undef DEBUG_TRACE
#define DEBUG_TRACE(x)
#else
#if defined(DEBUG)
#define DEBUG_TRACE(x) do { \
  flockfile(stdout); \
  printf("*** %lu.%p.%s.%d: ", \
         (unsigned long) time(NULL), (void *) pthread_self(), \
         __func__, __LINE__); \
  printf x; \
  putchar('\n'); \
  fflush(stdout); \
  funlockfile(stdout); \
} while (0)
#else
#define DEBUG_TRACE(x)
#endif // DEBUG
#endif // DEBUG_TRACE

// Darwin prior to 7.0 and Win32 do not have socklen_t
#ifdef NO_SOCKLEN_T
typedef int socklen_t;
#endif // NO_SOCKLEN_T
#define _DARWIN_UNLIMITED_SELECT

#define IP_ADDR_STR_LEN 50  // IPv6 hex string is 46 chars

#if !defined(MSG_NOSIGNAL)
#define MSG_NOSIGNAL 0
#endif

#if !defined(SOMAXCONN)
#define SOMAXCONN 100
#endif

#if !defined(PATH_MAX)
#define PATH_MAX 4096
#endif

// Size of the accepted socket queue
#if !defined(MGSQLEN)
#define MGSQLEN 20
#endif

static const char *http_500_error = "Internal Server Error";

#if defined(NO_SSL_DL)
#include <openssl/ssl.h>
#include <openssl/err.h>
#else
// SSL loaded dynamically from DLL.
// I put the prototypes here to be independent from OpenSSL source installation.
typedef struct ssl_st SSL;
typedef struct ssl_method_st SSL_METHOD;
typedef struct ssl_ctx_st SSL_CTX;

struct ssl_func {
    const char *name;   // SSL function name
    void  (*ptr)(void); // Function pointer
};

#define SSL_free (* (void (*)(SSL *)) ssl_sw[0].ptr)
#define SSL_accept (* (int (*)(SSL *)) ssl_sw[1].ptr)
#define SSL_connect (* (int (*)(SSL *)) ssl_sw[2].ptr)
#define SSL_read (* (int (*)(SSL *, void *, int)) ssl_sw[3].ptr)
#define SSL_write (* (int (*)(SSL *, const void *,int)) ssl_sw[4].ptr)
#define SSL_get_error (* (int (*)(SSL *, int)) ssl_sw[5].ptr)
#define SSL_set_fd (* (int (*)(SSL *, SOCKET)) ssl_sw[6].ptr)
#define SSL_new (* (SSL * (*)(SSL_CTX *)) ssl_sw[7].ptr)
#define SSL_CTX_new (* (SSL_CTX * (*)(SSL_METHOD *)) ssl_sw[8].ptr)
#define SSLv23_server_method (* (SSL_METHOD * (*)(void)) ssl_sw[9].ptr)
#define SSL_library_init (* (int (*)(void)) ssl_sw[10].ptr)
#define SSL_CTX_use_PrivateKey_file (* (int (*)(SSL_CTX *, \
        const char *, int)) ssl_sw[11].ptr)
#define SSL_CTX_use_certificate_file (* (int (*)(SSL_CTX *, \
        const char *, int)) ssl_sw[12].ptr)
#define SSL_CTX_set_default_passwd_cb \
  (* (void (*)(SSL_CTX *, mg_callback_t)) ssl_sw[13].ptr)
#define SSL_CTX_free (* (void (*)(SSL_CTX *)) ssl_sw[14].ptr)
#define SSL_load_error_strings (* (void (*)(void)) ssl_sw[15].ptr)
#define SSL_CTX_use_certificate_chain_file \
  (* (int (*)(SSL_CTX *, const char *)) ssl_sw[16].ptr)
#define SSLv23_client_method (* (SSL_METHOD * (*)(void)) ssl_sw[17].ptr)
#define SSL_pending (* (int (*)(SSL *)) ssl_sw[18].ptr)
#define SSL_CTX_set_verify (* (void (*)(SSL_CTX *, int, int)) ssl_sw[19].ptr)
#define SSL_shutdown (* (int (*)(SSL *)) ssl_sw[20].ptr)

#define CRYPTO_num_locks (* (int (*)(void)) crypto_sw[0].ptr)
#define CRYPTO_set_locking_callback \
  (* (void (*)(void (*)(int, int, const char *, int))) crypto_sw[1].ptr)
#define CRYPTO_set_id_callback \
  (* (void (*)(unsigned long (*)(void))) crypto_sw[2].ptr)
#define ERR_get_error (* (unsigned long (*)(void)) crypto_sw[3].ptr)
#define ERR_error_string (* (char * (*)(unsigned long,char *)) crypto_sw[4].ptr)

// set_ssl_option() function updates this array.
// It loads SSL library dynamically and changes NULLs to the actual addresses
// of respective functions. The macros above (like SSL_connect()) are really
// just calling these functions indirectly via the pointer.
static struct ssl_func ssl_sw[] = {
    {"SSL_free",   NULL},
    {"SSL_accept",   NULL},
    {"SSL_connect",   NULL},
    {"SSL_read",   NULL},
    {"SSL_write",   NULL},
    {"SSL_get_error",  NULL},
    {"SSL_set_fd",   NULL},
    {"SSL_new",   NULL},
    {"SSL_CTX_new",   NULL},
    {"SSLv23_server_method", NULL},
    {"SSL_library_init",  NULL},
    {"SSL_CTX_use_PrivateKey_file", NULL},
    {"SSL_CTX_use_certificate_file",NULL},
    {"SSL_CTX_set_default_passwd_cb",NULL},
    {"SSL_CTX_free",  NULL},
    {"SSL_load_error_strings", NULL},
    {"SSL_CTX_use_certificate_chain_file", NULL},
    {"SSLv23_client_method", NULL},
    {"SSL_pending", NULL},
    {"SSL_CTX_set_verify", NULL},
    {"SSL_shutdown",   NULL},
    {NULL,    NULL}
};

// Similar array as ssl_sw. These functions could be located in different lib.
#if !defined(NO_SSL)
static struct ssl_func crypto_sw[] = {
    {"CRYPTO_num_locks",  NULL},
    {"CRYPTO_set_locking_callback", NULL},
    {"CRYPTO_set_id_callback", NULL},
    {"ERR_get_error",  NULL},
    {"ERR_error_string", NULL},
    {NULL,    NULL}
};
#endif // NO_SSL
#endif // NO_SSL_DL

static const char *month_names[] = {
    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

// Unified socket address. For IPv6 support, add IPv6 address structure
// in the union u.
union usa {
    struct sockaddr sa;
    struct sockaddr_in sin;
#if defined(USE_IPV6)
    struct sockaddr_in6 sin6;
#endif
};

// Describes a string (chunk of memory).
struct vec {
    const char *ptr;
    size_t len;
};

struct file {
    int is_directory;
    time_t modification_time;
    int64_t size;
    FILE *fp;
    const char *membuf;   // Non-NULL if file data is in memory
    // set to 1 if the content is gzipped
    // in which case we need a content-encoding: gzip header
    int gzipped;
};
#define STRUCT_FILE_INITIALIZER {0, 0, 0, NULL, NULL, 0}

// Describes listening socket, or socket which was accept()-ed by the master
// thread and queued for future handling by the worker thread.
struct socket {
    SOCKET sock;          // Listening socket
    union usa lsa;        // Local socket address
    union usa rsa;        // Remote socket address
    unsigned is_ssl:1;    // Is port SSL-ed
    unsigned ssl_redir:1; // Is port supposed to redirect everything to SSL port
};

// NOTE(lsm): this enum shoulds be in sync with the config_options below.
enum {
    CGI_EXTENSIONS, CGI_ENVIRONMENT, PUT_DELETE_PASSWORDS_FILE, CGI_INTERPRETER,
    PROTECT_URI, AUTHENTICATION_DOMAIN, SSI_EXTENSIONS, THROTTLE,
    ACCESS_LOG_FILE, ENABLE_DIRECTORY_LISTING, ERROR_LOG_FILE,
    GLOBAL_PASSWORDS_FILE, INDEX_FILES, ENABLE_KEEP_ALIVE, ACCESS_CONTROL_LIST,
    EXTRA_MIME_TYPES, LISTENING_PORTS, DOCUMENT_ROOT, SSL_CERTIFICATE,
    NUM_THREADS, RUN_AS_USER, REWRITE, HIDE_FILES, REQUEST_TIMEOUT,
    NUM_OPTIONS
};

static const char *config_options[] = {
    "cgi_pattern", "**.cgi$|**.pl$|**.php$",
    "cgi_environment", NULL,
    "put_delete_auth_file", NULL,
    "cgi_interpreter", NULL,
    "protect_uri", NULL,
    "authentication_domain", "mydomain.com",
    "ssi_pattern", "**.shtml$|**.shtm$",
    "throttle", NULL,
    "access_log_file", NULL,
    "enable_directory_listing", "yes",
    "error_log_file", NULL,
    "global_auth_file", NULL,
    "index_files",
    "index.html,index.htm,index.cgi,index.shtml,index.php,index.lp",
    "enable_keep_alive", "no",
    "access_control_list", NULL,
    "extra_mime_types", NULL,
    "listening_ports", "8080",
    "document_root",  NULL,
    "ssl_certificate", NULL,
    "num_threads", "50",
    "run_as_user", NULL,
    "url_rewrite_patterns", NULL,
    "hide_files_patterns", NULL,
    "request_timeout_ms", "30000",
    NULL
};

struct mg_request_handler_info {
    char *uri;
    size_t uri_len;
    mg_request_handler handler;
    void *cbdata;
    struct mg_request_handler_info *next;
};

struct mg_context {
    volatile int stop_flag;         // Should we stop event loop
    void *ssllib_dll_handle;        // Store the ssl library handle.
    void *cryptolib_dll_handle;     // Store the crypto library handle.
    SSL_CTX *ssl_ctx;               // SSL context
    char *config[NUM_OPTIONS];      // Civetweb configuration parameters
    struct mg_callbacks callbacks;  // User-defined callback function
    void *user_data;                // User-defined data

    struct socket *listening_sockets;
    int num_listening_sockets;

    volatile int num_threads;  // Number of threads
    pthread_mutex_t mutex;     // Protects (max|num)_threads
    pthread_cond_t  cond;      // Condvar for tracking workers terminations

    struct socket queue[MGSQLEN];   // Accepted sockets
    volatile int sq_head;      // Head of the socket queue
    volatile int sq_tail;      // Tail of the socket queue
    pthread_cond_t sq_full;    // Signaled when socket is produced
    pthread_cond_t sq_empty;   // Signaled when socket is consumed
    pthread_t masterthreadid;  // The master thread ID.
    int workerthreadcount;     // The amount of worker threads.
    pthread_t *workerthreadids;// The worker thread IDs.

    // linked list of uri handlers
    struct mg_request_handler_info *request_handlers;
};

struct mg_connection {
    struct mg_request_info request_info;
    struct mg_context *ctx;
    SSL *ssl;                   // SSL descriptor
    SSL_CTX *client_ssl_ctx;    // SSL context for client connections
    struct socket client;       // Connected client
    time_t birth_time;          // Time when request was received
    int64_t num_bytes_sent;     // Total bytes sent to client
    int64_t content_len;        // Content-Length header value
    int64_t consumed_content;   // How many bytes of content have been read
    char *buf;                  // Buffer for received data
    char *path_info;            // PATH_INFO part of the URL
    int must_close;             // 1 if connection must be closed
    int buf_size;               // Buffer size
    int request_len;            // Size of the request + headers in a buffer
    int data_len;               // Total size of data in a buffer
    int status_code;            // HTTP reply status code, e.g. 200
    int throttle;               // Throttling, bytes/sec. <= 0 means no throttle
    time_t last_throttle_time;  // Last time throttled data was sent
    int64_t last_throttle_bytes;// Bytes sent this second
    pthread_mutex_t mutex;      // Used by mg_lock/mg_unlock to ensure atomic transmissions for websockets
};

// Directory entry
struct de {
    struct mg_connection *conn;
    char *file_name;
    struct file file;
};

const char **mg_get_valid_option_names(void)
{
    return config_options;
}

static int is_file_in_memory(struct mg_connection *conn, const char *path,
                             struct file *filep)
{
    size_t size = 0;
    if ((filep->membuf = conn->ctx->callbacks.open_file == NULL ? NULL :
                         conn->ctx->callbacks.open_file(conn, path, &size)) != NULL) {
        // NOTE: override filep->size only on success. Otherwise, it might break
        // constructs like if (!mg_stat() || !mg_fopen()) ...
        filep->size = size;
    }
    return filep->membuf != NULL;
}

static int is_file_opened(const struct file *filep)
{
    return filep->membuf != NULL || filep->fp != NULL;
}

static int mg_fopen(struct mg_connection *conn, const char *path,
                    const char *mode, struct file *filep)
{
    if (!is_file_in_memory(conn, path, filep)) {
#ifdef _WIN32
        wchar_t wbuf[PATH_MAX], wmode[20];
        to_unicode(path, wbuf, ARRAY_SIZE(wbuf));
        MultiByteToWideChar(CP_UTF8, 0, mode, -1, wmode, ARRAY_SIZE(wmode));
        filep->fp = _wfopen(wbuf, wmode);
#else
        filep->fp = fopen(path, mode);
#endif
    }

    return is_file_opened(filep);
}

static void mg_fclose(struct file *filep)
{
    if (filep != NULL && filep->fp != NULL) {
        fclose(filep->fp);
    }
}

static int get_option_index(const char *name)
{
    int i;

    for (i = 0; config_options[i * 2] != NULL; i++) {
        if (strcmp(config_options[i * 2], name) == 0) {
            return i;
        }
    }
    return -1;
}

const char *mg_get_option(const struct mg_context *ctx, const char *name)
{
    int i;
    if ((i = get_option_index(name)) == -1) {
        return NULL;
    } else if (ctx->config[i] == NULL) {
        return "";
    } else {
        return ctx->config[i];
    }
}

static void sockaddr_to_string(char *buf, size_t len,
                               const union usa *usa)
{
    buf[0] = '\0';
#if defined(USE_IPV6)
    inet_ntop(usa->sa.sa_family, usa->sa.sa_family == AF_INET ?
              (void *) &usa->sin.sin_addr :
              (void *) &usa->sin6.sin6_addr, buf, len);
#elif defined(_WIN32)
    // Only Windoze Vista (and newer) have inet_ntop()
    strncpy(buf, inet_ntoa(usa->sin.sin_addr), len);
#else
    inet_ntop(usa->sa.sa_family, (void *) &usa->sin.sin_addr, buf, len);
#endif
}

// Print error message to the opened error log stream.
void mg_cry(struct mg_connection *conn, const char *fmt, ...)
{
    char buf[MG_BUF_LEN], src_addr[IP_ADDR_STR_LEN];
    va_list ap;
    FILE *fp;
    time_t timestamp;

    va_start(ap, fmt);
    IGNORE_UNUSED_RESULT(vsnprintf(buf, sizeof(buf), fmt, ap));
    va_end(ap);

    // Do not lock when getting the callback value, here and below.
    // I suppose this is fine, since function cannot disappear in the
    // same way string option can.
    if (conn->ctx->callbacks.log_message == NULL ||
        conn->ctx->callbacks.log_message(conn, buf) == 0) {
        fp = conn->ctx->config[ERROR_LOG_FILE] == NULL ? NULL :
             fopen(conn->ctx->config[ERROR_LOG_FILE], "a+");

        if (fp != NULL) {
            flockfile(fp);
            timestamp = time(NULL);

            sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);
            fprintf(fp, "[%010lu] [error] [client %s] ", (unsigned long) timestamp,
                    src_addr);

            if (conn->request_info.request_method != NULL) {
                fprintf(fp, "%s %s: ", conn->request_info.request_method,
                        conn->request_info.uri);
            }

            fprintf(fp, "%s", buf);
            fputc('\n', fp);
            funlockfile(fp);
            fclose(fp);
        }
    }
}

// Return fake connection structure. Used for logging, if connection
// is not applicable at the moment of logging.
static struct mg_connection *fc(struct mg_context *ctx)
{
    static struct mg_connection fake_connection;
    fake_connection.ctx = ctx;
    return &fake_connection;
}

const char *mg_version(void)
{
    return CIVETWEB_VERSION;
}

struct mg_request_info *mg_get_request_info(struct mg_connection *conn)
{
    return &conn->request_info;
}

static void mg_strlcpy(register char *dst, register const char *src, size_t n)
{
    for (; *src != '\0' && n > 1; n--) {
        *dst++ = *src++;
    }
    *dst = '\0';
}

static int lowercase(const char *s)
{
    return tolower(* (const unsigned char *) s);
}

int mg_strncasecmp(const char *s1, const char *s2, size_t len)
{
    int diff = 0;

    if (len > 0)
        do {
            diff = lowercase(s1++) - lowercase(s2++);
        } while (diff == 0 && s1[-1] != '\0' && --len > 0);

    return diff;
}

static int mg_strcasecmp(const char *s1, const char *s2)
{
    int diff;

    do {
        diff = lowercase(s1++) - lowercase(s2++);
    } while (diff == 0 && s1[-1] != '\0');

    return diff;
}

static char * mg_strndup(const char *ptr, size_t len)
{
    char *p;

    if ((p = (char *) malloc(len + 1)) != NULL) {
        mg_strlcpy(p, ptr, len + 1);
    }

    return p;
}

static char * mg_strdup(const char *str)
{
    return mg_strndup(str, strlen(str));
}

static const char *mg_strcasestr(const char *big_str, const char *small_str)
{
    int i, big_len = (int)strlen(big_str), small_len = (int)strlen(small_str);

    for (i = 0; i <= big_len - small_len; i++) {
        if (mg_strncasecmp(big_str + i, small_str, small_len) == 0) {
            return big_str + i;
        }
    }

    return NULL;
}

// Like snprintf(), but never returns negative value, or a value
// that is larger than a supplied buffer.
// Thanks to Adam Zeldis to pointing snprintf()-caused vulnerability
// in his audit report.
static int mg_vsnprintf(struct mg_connection *conn, char *buf, size_t buflen,
                        const char *fmt, va_list ap)
{
    int n;

    if (buflen == 0)
        return 0;

    n = vsnprintf(buf, buflen, fmt, ap);

    if (n < 0) {
        mg_cry(conn, "vsnprintf error");
        n = 0;
    } else if (n >= (int) buflen) {
        mg_cry(conn, "truncating vsnprintf buffer: [%.*s]",
               n > 200 ? 200 : n, buf);
        n = (int) buflen - 1;
    }
    buf[n] = '\0';

    return n;
}

static int mg_snprintf(struct mg_connection *conn, char *buf, size_t buflen,
                       PRINTF_FORMAT_STRING(const char *fmt), ...)
PRINTF_ARGS(4, 5);

static int mg_snprintf(struct mg_connection *conn, char *buf, size_t buflen,
                       const char *fmt, ...)
{
    va_list ap;
    int n;

    va_start(ap, fmt);
    n = mg_vsnprintf(conn, buf, buflen, fmt, ap);
    va_end(ap);

    return n;
}

// Skip the characters until one of the delimiters characters found.
// 0-terminate resulting word. Skip the delimiter and following whitespaces.
// Advance pointer to buffer to the next word. Return found 0-terminated word.
// Delimiters can be quoted with quotechar.
static char *skip_quoted(char **buf, const char *delimiters,
                         const char *whitespace, char quotechar)
{
    char *p, *begin_word, *end_word, *end_whitespace;

    begin_word = *buf;
    end_word = begin_word + strcspn(begin_word, delimiters);

    // Check for quotechar
    if (end_word > begin_word) {
        p = end_word - 1;
        while (*p == quotechar) {
            // If there is anything beyond end_word, copy it
            if (*end_word == '\0') {
                *p = '\0';
                break;
            } else {
                size_t end_off = strcspn(end_word + 1, delimiters);
                memmove (p, end_word, end_off + 1);
                p += end_off; // p must correspond to end_word - 1
                end_word += end_off + 1;
            }
        }
        for (p++; p < end_word; p++) {
            *p = '\0';
        }
    }

    if (*end_word == '\0') {
        *buf = end_word;
    } else {
        end_whitespace = end_word + 1 + strspn(end_word + 1, whitespace);

        for (p = end_word; p < end_whitespace; p++) {
            *p = '\0';
        }

        *buf = end_whitespace;
    }

    return begin_word;
}

// Simplified version of skip_quoted without quote char
// and whitespace == delimiters
static char *skip(char **buf, const char *delimiters)
{
    return skip_quoted(buf, delimiters, delimiters, 0);
}


// Return HTTP header value, or NULL if not found.
static const char *get_header(const struct mg_request_info *ri,
                              const char *name)
{
    int i;

    for (i = 0; i < ri->num_headers; i++)
        if (!mg_strcasecmp(name, ri->http_headers[i].name))
            return ri->http_headers[i].value;

    return NULL;
}

const char *mg_get_header(const struct mg_connection *conn, const char *name)
{
    return get_header(&conn->request_info, name);
}

// A helper function for traversing a comma separated list of values.
// It returns a list pointer shifted to the next value, or NULL if the end
// of the list found.
// Value is stored in val vector. If value has form "x=y", then eq_val
// vector is initialized to point to the "y" part, and val vector length
// is adjusted to point only to "x".
static const char *next_option(const char *list, struct vec *val,
                               struct vec *eq_val)
{
    if (list == NULL || *list == '\0') {
        // End of the list
        list = NULL;
    } else {
        val->ptr = list;
        if ((list = strchr(val->ptr, ',')) != NULL) {
            // Comma found. Store length and shift the list ptr
            val->len = list - val->ptr;
            list++;
        } else {
            // This value is the last one
            list = val->ptr + strlen(val->ptr);
            val->len = list - val->ptr;
        }

        if (eq_val != NULL) {
            // Value has form "x=y", adjust pointers and lengths
            // so that val points to "x", and eq_val points to "y".
            eq_val->len = 0;
            eq_val->ptr = (const char *) memchr(val->ptr, '=', val->len);
            if (eq_val->ptr != NULL) {
                eq_val->ptr++;  // Skip over '=' character
                eq_val->len = val->ptr + val->len - eq_val->ptr;
                val->len = (eq_val->ptr - val->ptr) - 1;
            }
        }
    }

    return list;
}

// Perform case-insensitive match of string against pattern
static int match_prefix(const char *pattern, int pattern_len, const char *str)
{
    const char *or_str;
    int i, j, len, res;

    if ((or_str = (const char *) memchr(pattern, '|', pattern_len)) != NULL) {
        res = match_prefix(pattern, (int)(or_str - pattern), str);
        return res > 0 ? res :
               match_prefix(or_str + 1, (int)((pattern + pattern_len) - (or_str + 1)), str);
    }

    i = j = 0;
    res = -1;
    for (; i < pattern_len; i++, j++) {
        if (pattern[i] == '?' && str[j] != '\0') {
            continue;
        } else if (pattern[i] == '$') {
            return str[j] == '\0' ? j : -1;
        } else if (pattern[i] == '*') {
            i++;
            if (pattern[i] == '*') {
                i++;
                len = (int) strlen(str + j);
            } else {
                len = (int) strcspn(str + j, "/");
            }
            if (i == pattern_len) {
                return j + len;
            }
            do {
                res = match_prefix(pattern + i, pattern_len - i, str + j + len);
            } while (res == -1 && len-- > 0);
            return res == -1 ? -1 : j + res + len;
        } else if (lowercase(&pattern[i]) != lowercase(&str[j])) {
            return -1;
        }
    }
    return j;
}

// HTTP 1.1 assumes keep alive if "Connection:" header is not set
// This function must tolerate situations when connection info is not
// set up, for example if request parsing failed.
static int should_keep_alive(const struct mg_connection *conn)
{
    const char *http_version = conn->request_info.http_version;
    const char *header = mg_get_header(conn, "Connection");
    if (conn->must_close ||
        conn->status_code == 401 ||
        mg_strcasecmp(conn->ctx->config[ENABLE_KEEP_ALIVE], "yes") != 0 ||
        (header != NULL && mg_strcasecmp(header, "keep-alive") != 0) ||
        (header == NULL && http_version && strcmp(http_version, "1.1"))) {
        return 0;
    }
    return 1;
}

static const char *suggest_connection_header(const struct mg_connection *conn)
{
    return should_keep_alive(conn) ? "keep-alive" : "close";
}

static void send_http_error(struct mg_connection *, int, const char *,
                            PRINTF_FORMAT_STRING(const char *fmt), ...)
PRINTF_ARGS(4, 5);


static void send_http_error(struct mg_connection *conn, int status,
                            const char *reason, const char *fmt, ...)
{
    char buf[MG_BUF_LEN];
    va_list ap;
    int len = 0;

    conn->status_code = status;
    if (conn->ctx->callbacks.http_error == NULL ||
        conn->ctx->callbacks.http_error(conn, status)) {
        buf[0] = '\0';

        // Errors 1xx, 204 and 304 MUST NOT send a body
        if (status > 199 && status != 204 && status != 304) {
            len = mg_snprintf(conn, buf, sizeof(buf), "Error %d: %s", status, reason);
            buf[len++] = '\n';

            va_start(ap, fmt);
            len += mg_vsnprintf(conn, buf + len, sizeof(buf) - len, fmt, ap);
            va_end(ap);
        }
        DEBUG_TRACE(("[%s]", buf));

        mg_printf(conn, "HTTP/1.1 %d %s\r\n"
                  "Content-Length: %d\r\n"
                  "Connection: %s\r\n\r\n", status, reason, len,
                  suggest_connection_header(conn));
        conn->num_bytes_sent += mg_printf(conn, "%s", buf);
    }
}

#if defined(_WIN32) && !defined(__SYMBIAN32__)
static int pthread_mutex_init(pthread_mutex_t *mutex, void *unused)
{
    (void) unused;
    *mutex = CreateMutex(NULL, FALSE, NULL);
    return *mutex == NULL ? -1 : 0;
}

static int pthread_mutex_destroy(pthread_mutex_t *mutex)
{
    return CloseHandle(*mutex) == 0 ? -1 : 0;
}

static int pthread_mutex_lock(pthread_mutex_t *mutex)
{
    return WaitForSingleObject(*mutex, INFINITE) == WAIT_OBJECT_0? 0 : -1;
}

static int pthread_mutex_unlock(pthread_mutex_t *mutex)
{
    return ReleaseMutex(*mutex) == 0 ? -1 : 0;
}

static int pthread_cond_init(pthread_cond_t *cv, const void *unused)
{
    (void) unused;
    InitializeCriticalSection(&cv->threadIdSec);
    cv->waitingthreadcount = 0;
    cv->waitingthreadids = calloc(MAX_WORKER_THREADS, sizeof(pthread_t));
    return (cv->waitingthreadids!=NULL) ? 0 : -1;
}

static int pthread_cond_wait(pthread_cond_t *cv, pthread_mutex_t *mutex)
{
    EnterCriticalSection(&cv->threadIdSec);
    assert(cv->waitingthreadcount < MAX_WORKER_THREADS);
    cv->waitingthreadids[cv->waitingthreadcount] = OpenThread(THREAD_SUSPEND_RESUME, FALSE, GetCurrentThreadId());
    cv->waitingthreadcount++;
    LeaveCriticalSection(&cv->threadIdSec);

    pthread_mutex_unlock(mutex); /* if the thread is preempted here, ResumeThread will return 0 */
    SuspendThread(GetCurrentThread()); /* if the thread reached this point, ResumeThread will return 1 */
    pthread_mutex_lock(mutex);

    return 0;
}

static int pthread_cond_signal(pthread_cond_t *cv)
{
    int i,j;
    DWORD susCnt;
    HANDLE wkup = NULL;

    EnterCriticalSection(&cv->threadIdSec);
    for (j=0; j<cv->waitingthreadcount; j++) {
      wkup = cv->waitingthreadids[j];
      susCnt = ResumeThread(wkup);
      assert(susCnt<2);
      if (susCnt==1) {
          CloseHandle(wkup);
          for (i=1;i<cv->waitingthreadcount;i++) {
              cv->waitingthreadids[i-1] = cv->waitingthreadids[i];
          }
          cv->waitingthreadcount--;
          break;
      }
    }
    LeaveCriticalSection(&cv->threadIdSec);

    return 0;
}

static int pthread_cond_broadcast(pthread_cond_t *cv)
{
    /* The only usecase here is after a call to mg_exit. */
    /* This will work here, for WinCE (realtime) one could switch the thread priority of the master thread to below normal when exit is performed. */
    EnterCriticalSection(&cv->threadIdSec);
    while (cv->waitingthreadcount) {
        pthread_cond_signal(cv);
    }
    LeaveCriticalSection(&cv->threadIdSec);

    return 0;
}

static int pthread_cond_destroy(pthread_cond_t *cv)
{
    EnterCriticalSection(&cv->threadIdSec);
    assert(cv->waitingthreadcount==0);
    cv->waitingthreadids = 0;
    free(cv->waitingthreadids);
    LeaveCriticalSection(&cv->threadIdSec);
    DeleteCriticalSection(&cv->threadIdSec);

    return 0;
}

// For Windows, change all slashes to backslashes in path names.
static void change_slashes_to_backslashes(char *path)
{
    int i;

    for (i = 0; path[i] != '\0'; i++) {
        if (path[i] == '/')
            path[i] = '\\';
        // i > 0 check is to preserve UNC paths, like \\server\file.txt
        if (path[i] == '\\' && i > 0)
            while (path[i + 1] == '\\' || path[i + 1] == '/')
                (void) memmove(path + i + 1,
                               path + i + 2, strlen(path + i + 1));
    }
}

// Encode 'path' which is assumed UTF-8 string, into UNICODE string.
// wbuf and wbuf_len is a target buffer and its length.
static void to_unicode(const char *path, wchar_t *wbuf, size_t wbuf_len)
{
    char buf[PATH_MAX], buf2[PATH_MAX];

    mg_strlcpy(buf, path, sizeof(buf));
    change_slashes_to_backslashes(buf);

    // Convert to Unicode and back. If doubly-converted string does not
    // match the original, something is fishy, reject.
    memset(wbuf, 0, wbuf_len * sizeof(wchar_t));
    MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, (int) wbuf_len);
    WideCharToMultiByte(CP_UTF8, 0, wbuf, (int) wbuf_len, buf2, sizeof(buf2),
                        NULL, NULL);
    if (strcmp(buf, buf2) != 0) {
        wbuf[0] = L'\0';
    }
}

#if defined(_WIN32_WCE)
static time_t time(time_t *ptime)
{
    time_t t;
    SYSTEMTIME st;
    FILETIME ft;

    GetSystemTime(&st);
    SystemTimeToFileTime(&st, &ft);
    t = SYS2UNIX_TIME(ft.dwLowDateTime, ft.dwHighDateTime);

    if (ptime != NULL) {
        *ptime = t;
    }

    return t;
}

static struct tm *localtime(const time_t *ptime, struct tm *ptm)
{
    int64_t t = ((int64_t) *ptime) * RATE_DIFF + EPOCH_DIFF;
    FILETIME ft, lft;
    SYSTEMTIME st;
    TIME_ZONE_INFORMATION tzinfo;

    if (ptm == NULL) {
        return NULL;
    }

    * (int64_t *) &ft = t;
    FileTimeToLocalFileTime(&ft, &lft);
    FileTimeToSystemTime(&lft, &st);
    ptm->tm_year = st.wYear - 1900;
    ptm->tm_mon = st.wMonth - 1;
    ptm->tm_wday = st.wDayOfWeek;
    ptm->tm_mday = st.wDay;
    ptm->tm_hour = st.wHour;
    ptm->tm_min = st.wMinute;
    ptm->tm_sec = st.wSecond;
    ptm->tm_yday = 0; // hope nobody uses this
    ptm->tm_isdst =
        GetTimeZoneInformation(&tzinfo) == TIME_ZONE_ID_DAYLIGHT ? 1 : 0;

    return ptm;
}

static struct tm *gmtime(const time_t *ptime, struct tm *ptm)
{
    // FIXME(lsm): fix this.
    return localtime(ptime, ptm);
}

static size_t strftime(char *dst, size_t dst_size, const char *fmt,
                       const struct tm *tm)
{
    (void) snprintf(dst, dst_size, "implement strftime() for WinCE");
    return 0;
}
#endif

// Windows happily opens files with some garbage at the end of file name.
// For example, fopen("a.cgi    ", "r") on Windows successfully opens
// "a.cgi", despite one would expect an error back.
// This function returns non-0 if path ends with some garbage.
static int path_cannot_disclose_cgi(const char *path)
{
    static const char *allowed_last_characters = "_-";
    int last = path[strlen(path) - 1];
    return isalnum(last) || strchr(allowed_last_characters, last) != NULL;
}

static int mg_stat(struct mg_connection *conn, const char *path,
                   struct file *filep)
{
    wchar_t wbuf[PATH_MAX];
    WIN32_FILE_ATTRIBUTE_DATA info;

    if (!is_file_in_memory(conn, path, filep)) {
        to_unicode(path, wbuf, ARRAY_SIZE(wbuf));
        if (GetFileAttributesExW(wbuf, GetFileExInfoStandard, &info) != 0) {
            filep->size = MAKEUQUAD(info.nFileSizeLow, info.nFileSizeHigh);
            filep->modification_time = SYS2UNIX_TIME(
                                           info.ftLastWriteTime.dwLowDateTime,
                                           info.ftLastWriteTime.dwHighDateTime);
            filep->is_directory = info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
            // If file name is fishy, reset the file structure and return error.
            // Note it is important to reset, not just return the error, cause
            // functions like is_file_opened() check the struct.
            if (!filep->is_directory && !path_cannot_disclose_cgi(path)) {
                memset(filep, 0, sizeof(*filep));
            }
        }
    }

    return filep->membuf != NULL || filep->modification_time != 0;
}

static int mg_remove(const char *path)
{
    wchar_t wbuf[PATH_MAX];
    to_unicode(path, wbuf, ARRAY_SIZE(wbuf));
    return DeleteFileW(wbuf) ? 0 : -1;
}

static int mg_mkdir(const char *path, int mode)
{
    char buf[PATH_MAX];
    wchar_t wbuf[PATH_MAX];

    (void) mode;
    mg_strlcpy(buf, path, sizeof(buf));
    change_slashes_to_backslashes(buf);

    (void) MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, ARRAY_SIZE(wbuf));

    return CreateDirectoryW(wbuf, NULL) ? 0 : -1;
}

// Implementation of POSIX opendir/closedir/readdir for Windows.
static DIR * opendir(const char *name)
{
    DIR *dir = NULL;
    wchar_t wpath[PATH_MAX];
    DWORD attrs;

    if (name == NULL) {
        SetLastError(ERROR_BAD_ARGUMENTS);
    } else if ((dir = (DIR *) malloc(sizeof(*dir))) == NULL) {
        SetLastError(ERROR_NOT_ENOUGH_MEMORY);
    } else {
        to_unicode(name, wpath, ARRAY_SIZE(wpath));
        attrs = GetFileAttributesW(wpath);
        if (attrs != 0xFFFFFFFF &&
            ((attrs & FILE_ATTRIBUTE_DIRECTORY) == FILE_ATTRIBUTE_DIRECTORY)) {
            (void) wcscat(wpath, L"\\*");
            dir->handle = FindFirstFileW(wpath, &dir->info);
            dir->result.d_name[0] = '\0';
        } else {
            free(dir);
            dir = NULL;
        }
    }

    return dir;
}

static int closedir(DIR *dir)
{
    int result = 0;

    if (dir != NULL) {
        if (dir->handle != INVALID_HANDLE_VALUE)
            result = FindClose(dir->handle) ? 0 : -1;

        free(dir);
    } else {
        result = -1;
        SetLastError(ERROR_BAD_ARGUMENTS);
    }

    return result;
}

static struct dirent *readdir(DIR *dir)
{
    struct dirent *result = 0;

    if (dir) {
        if (dir->handle != INVALID_HANDLE_VALUE) {
            result = &dir->result;
            (void) WideCharToMultiByte(CP_UTF8, 0,
                                       dir->info.cFileName, -1, result->d_name,
                                       sizeof(result->d_name), NULL, NULL);

            if (!FindNextFileW(dir->handle, &dir->info)) {
                (void) FindClose(dir->handle);
                dir->handle = INVALID_HANDLE_VALUE;
            }

        } else {
            SetLastError(ERROR_FILE_NOT_FOUND);
        }
    } else {
        SetLastError(ERROR_BAD_ARGUMENTS);
    }

    return result;
}

#ifndef HAVE_POLL
static int poll(struct pollfd *pfd, int n, int milliseconds)
{
    struct timeval tv;
    fd_set set;
    int i, result;
    SOCKET maxfd = 0;

    tv.tv_sec = milliseconds / 1000;
    tv.tv_usec = (milliseconds % 1000) * 1000;
    FD_ZERO(&set);

    for (i = 0; i < n; i++) {
        FD_SET((SOCKET) pfd[i].fd, &set);
        pfd[i].revents = 0;

        if (pfd[i].fd > maxfd) {
            maxfd = pfd[i].fd;
        }
    }

    if ((result = select((int)maxfd + 1, &set, NULL, NULL, &tv)) > 0) {
        for (i = 0; i < n; i++) {
            if (FD_ISSET(pfd[i].fd, &set)) {
                pfd[i].revents = POLLIN;
            }
        }
    }

    return result;
}
#endif // HAVE_POLL

static void set_close_on_exec(SOCKET sock, struct mg_connection *conn /* may be null */)
{
    (void) conn; /* Unused. */
    (void) SetHandleInformation((HANDLE) sock, HANDLE_FLAG_INHERIT, 0);
}

int mg_start_thread(mg_thread_func_t f, void *p)
{
#if defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1)
    // Compile-time option to control stack size, e.g. -DUSE_STACK_SIZE=16384
    return (long)_beginthread((void (__cdecl *)(void *)) f, USE_STACK_SIZE, p) == -1L ? -1 : 0;
#else
    return (long)_beginthread((void (__cdecl *)(void *)) f, 0, p) == -1L ? -1 : 0;
#endif /* defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1) */
}

/* Start a thread storing the thread context. */

static int mg_start_thread_with_id(unsigned (__stdcall *f)(void *), void *p,
                                   pthread_t *threadidptr)
{
    uintptr_t uip;
    HANDLE threadhandle;
    int result;

    uip = _beginthreadex(NULL, 0, (unsigned (__stdcall *)(void *)) f, p, 0,
                         NULL);
    threadhandle = (HANDLE) uip;
    if (threadidptr != NULL) {
        *threadidptr = threadhandle;
    }
    result = (threadhandle == NULL) ? -1 : 0;

    return result;
}

/* Wait for a thread to finish. */

static int mg_join_thread(pthread_t threadid)
{
    int result;
    DWORD dwevent;

    result = -1;
    dwevent = WaitForSingleObject(threadid, INFINITE);
    if (dwevent == WAIT_FAILED) {
        int err;

        err = GetLastError();
        DEBUG_TRACE(("WaitForSingleObject() failed, error %d", err));
    } else {
        if (dwevent == WAIT_OBJECT_0) {
            CloseHandle(threadid);
            result = 0;
        }
    }

    return result;
}

static HANDLE dlopen(const char *dll_name, int flags)
{
    wchar_t wbuf[PATH_MAX];
    (void) flags;
    to_unicode(dll_name, wbuf, ARRAY_SIZE(wbuf));
    return LoadLibraryW(wbuf);
}

static int dlclose(void *handle)
{
    int result;

    if (FreeLibrary(handle) != 0) {
        result = 0;
    } else {
        result = -1;
    }

    return result;
}

#if !defined(NO_CGI)
#define SIGKILL 0
static int kill(pid_t pid, int sig_num)
{
    (void) TerminateProcess(pid, sig_num);
    (void) CloseHandle(pid);
    return 0;
}

static void trim_trailing_whitespaces(char *s)
{
    char *e = s + strlen(s) - 1;
    while (e > s && isspace(* (unsigned char *) e)) {
        *e-- = '\0';
    }
}

static pid_t spawn_process(struct mg_connection *conn, const char *prog,
                           char *envblk, char *envp[], int fdin,
                           int fdout, const char *dir)
{
    HANDLE me;
    char *p, *interp, full_interp[PATH_MAX], full_dir[PATH_MAX],
         cmdline[PATH_MAX], buf[PATH_MAX];
    struct file file = STRUCT_FILE_INITIALIZER;
    STARTUPINFOA si;
    PROCESS_INFORMATION pi = { 0 };

    (void) envp;

    memset(&si, 0, sizeof(si));
    si.cb = sizeof(si);

    // TODO(lsm): redirect CGI errors to the error log file
    si.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
    si.wShowWindow = SW_HIDE;

    me = GetCurrentProcess();
    DuplicateHandle(me, (HANDLE) _get_osfhandle(fdin), me,
                    &si.hStdInput, 0, TRUE, DUPLICATE_SAME_ACCESS);
    DuplicateHandle(me, (HANDLE) _get_osfhandle(fdout), me,
                    &si.hStdOutput, 0, TRUE, DUPLICATE_SAME_ACCESS);

    // If CGI file is a script, try to read the interpreter line
    interp = conn->ctx->config[CGI_INTERPRETER];
    if (interp == NULL) {
        buf[0] = buf[1] = '\0';

        // Read the first line of the script into the buffer
        snprintf(cmdline, sizeof(cmdline), "%s%c%s", dir, '/', prog);
        if (mg_fopen(conn, cmdline, "r", &file)) {
            p = (char *) file.membuf;
            mg_fgets(buf, sizeof(buf), &file, &p);
            mg_fclose(&file);
            buf[sizeof(buf) - 1] = '\0';
        }

        if (buf[0] == '#' && buf[1] == '!') {
            trim_trailing_whitespaces(buf + 2);
        } else {
            buf[2] = '\0';
        }
        interp = buf + 2;
    }

    if (interp[0] != '\0') {
        GetFullPathNameA(interp, sizeof(full_interp), full_interp, NULL);
        interp = full_interp;
    }
    GetFullPathNameA(dir, sizeof(full_dir), full_dir, NULL);

    mg_snprintf(conn, cmdline, sizeof(cmdline), "%s%s\"%s\\%s\"",
                interp, interp[0] == '\0' ? "" : " ", full_dir, prog);

    DEBUG_TRACE(("Running [%s]", cmdline));
    if (CreateProcessA(NULL, cmdline, NULL, NULL, TRUE,
                       CREATE_NEW_PROCESS_GROUP, envblk, NULL, &si, &pi) == 0) {
        mg_cry(conn, "%s: CreateProcess(%s): %ld",
               __func__, cmdline, ERRNO);
        pi.hProcess = (pid_t) -1;
    }

    (void) CloseHandle(si.hStdOutput);
    (void) CloseHandle(si.hStdInput);
    if (pi.hThread != NULL)
        (void) CloseHandle(pi.hThread);

    return (pid_t) pi.hProcess;
}
#endif // !NO_CGI

static int set_non_blocking_mode(SOCKET sock)
{
    unsigned long on = 1;
    return ioctlsocket(sock, FIONBIO, &on);
}

#else
static int mg_stat(struct mg_connection *conn, const char *path,
                   struct file *filep)
{
    struct stat st;

    if (!is_file_in_memory(conn, path, filep) && !stat(path, &st)) {
        filep->size = st.st_size;
        filep->modification_time = st.st_mtime;
        filep->is_directory = S_ISDIR(st.st_mode);
    } else {
        filep->modification_time = (time_t) 0;
    }

    return filep->membuf != NULL || filep->modification_time != (time_t) 0;
}

static void set_close_on_exec(int fd, struct mg_connection *conn /* may be null */)
{
    if (fcntl(fd, F_SETFD, FD_CLOEXEC) != 0) {
        if (conn)
            mg_cry(conn, "%s: fcntl(F_SETFD FD_CLOEXEC) failed: %s",
                   __func__, strerror(ERRNO));
    }
}

int mg_start_thread(mg_thread_func_t func, void *param)
{
    pthread_t thread_id;
    pthread_attr_t attr;
    int result;

    (void) pthread_attr_init(&attr);
    (void) pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

#if defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1)
    // Compile-time option to control stack size, e.g. -DUSE_STACK_SIZE=16384
    (void) pthread_attr_setstacksize(&attr, USE_STACK_SIZE);
#endif /* defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1) */

    result = pthread_create(&thread_id, &attr, func, param);
    pthread_attr_destroy(&attr);

    return result;
}

/* Start a thread storing the thread context. */

static int mg_start_thread_with_id(mg_thread_func_t func, void *param,
                                   pthread_t *threadidptr)
{
    pthread_t thread_id;
    pthread_attr_t attr;
    int result;

    (void) pthread_attr_init(&attr);

#if defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1)
    // Compile-time option to control stack size, e.g. -DUSE_STACK_SIZE=16384
    (void) pthread_attr_setstacksize(&attr, USE_STACK_SIZE);
#endif /* defined(USE_STACK_SIZE) && USE_STACK_SIZE > 1 */

    result = pthread_create(&thread_id, &attr, func, param);
    pthread_attr_destroy(&attr);
    if (threadidptr != NULL) {
        *threadidptr = thread_id;
    }
    return result;
}

/* Wait for a thread to finish. */

static int mg_join_thread(pthread_t threadid)
{
    int result;

    result = pthread_join(threadid, NULL);
    return result;
}

#ifndef NO_CGI
static pid_t spawn_process(struct mg_connection *conn, const char *prog,
                           char *envblk, char *envp[], int fdin,
                           int fdout, const char *dir)
{
    pid_t pid;
    const char *interp;

    (void) envblk;

    if ((pid = fork()) == -1) {
        // Parent
        send_http_error(conn, 500, http_500_error, "fork(): %s", strerror(ERRNO));
    } else if (pid == 0) {
        // Child
        if (chdir(dir) != 0) {
            mg_cry(conn, "%s: chdir(%s): %s", __func__, dir, strerror(ERRNO));
        } else if (dup2(fdin, 0) == -1) {
            mg_cry(conn, "%s: dup2(%d, 0): %s", __func__, fdin, strerror(ERRNO));
        } else if (dup2(fdout, 1) == -1) {
            mg_cry(conn, "%s: dup2(%d, 1): %s", __func__, fdout, strerror(ERRNO));
        } else {
            // Not redirecting stderr to stdout, to avoid output being littered
            // with the error messages.
            (void) close(fdin);
            (void) close(fdout);

            // After exec, all signal handlers are restored to their default values,
            // with one exception of SIGCHLD. According to POSIX.1-2001 and Linux's
            // implementation, SIGCHLD's handler will leave unchanged after exec
            // if it was set to be ignored. Restore it to default action.
            signal(SIGCHLD, SIG_DFL);

            interp = conn->ctx->config[CGI_INTERPRETER];
            if (interp == NULL) {
                (void) execle(prog, prog, NULL, envp);
                mg_cry(conn, "%s: execle(%s): %s", __func__, prog, strerror(ERRNO));
            } else {
                (void) execle(interp, interp, prog, NULL, envp);
                mg_cry(conn, "%s: execle(%s %s): %s", __func__, interp, prog,
                       strerror(ERRNO));
            }
        }
        exit(EXIT_FAILURE);
    }

    return pid;
}
#endif // !NO_CGI

static int set_non_blocking_mode(SOCKET sock)
{
    int flags;

    flags = fcntl(sock, F_GETFL, 0);
    (void) fcntl(sock, F_SETFL, flags | O_NONBLOCK);

    return 0;
}
#endif // _WIN32

// Write data to the IO channel - opened file descriptor, socket or SSL
// descriptor. Return number of bytes written.
static int64_t push(FILE *fp, SOCKET sock, SSL *ssl, const char *buf,
                    int64_t len)
{
    int64_t sent;
    int n, k;

    (void) ssl;  // Get rid of warning
    sent = 0;
    while (sent < len) {

        // How many bytes we send in this iteration
        k = len - sent > INT_MAX ? INT_MAX : (int) (len - sent);

#ifndef NO_SSL
        if (ssl != NULL) {
            n = SSL_write(ssl, buf + sent, k);
        } else
#endif
            if (fp != NULL) {
                n = (int) fwrite(buf + sent, 1, (size_t) k, fp);
                if (ferror(fp))
                    n = -1;
            } else {
                n = send(sock, buf + sent, (size_t) k, MSG_NOSIGNAL);
            }

        if (n <= 0)
            break;

        sent += n;
    }

    return sent;
}

// Read from IO channel - opened file descriptor, socket, or SSL descriptor.
// Return negative value on error, or number of bytes read on success.
static int pull(FILE *fp, struct mg_connection *conn, char *buf, int len)
{
    int nread;

    if (fp != NULL) {
        // Use read() instead of fread(), because if we're reading from the CGI
        // pipe, fread() may block until IO buffer is filled up. We cannot afford
        // to block and must pass all read bytes immediately to the client.
        nread = read(fileno(fp), buf, (size_t) len);
#ifndef NO_SSL
    } else if (conn->ssl != NULL) {
        nread = SSL_read(conn->ssl, buf, len);
#endif
    } else {
        nread = recv(conn->client.sock, buf, (size_t) len, 0);
    }

    return conn->ctx->stop_flag ? -1 : nread;
}

static int pull_all(FILE *fp, struct mg_connection *conn, char *buf, int len)
{
    int n, nread = 0;

    while (len > 0 && conn->ctx->stop_flag == 0) {
        n = pull(fp, conn, buf + nread, len);
        if (n < 0) {
            nread = n;  // Propagate the error
            break;
        } else if (n == 0) {
            break;  // No more data to read
        } else {
            conn->consumed_content += n;
            nread += n;
            len -= n;
        }
    }

    return nread;
}

int mg_read(struct mg_connection *conn, void *buf, size_t len)
{
    int n, buffered_len, nread;
    const char *body;

    // If Content-Length is not set, read until socket is closed
    if (conn->consumed_content == 0 && conn->content_len == 0) {
        conn->content_len = INT64_MAX;
        conn->must_close = 1;
    }

    nread = 0;
    if (conn->consumed_content < conn->content_len) {
        // Adjust number of bytes to read.
        int64_t to_read = conn->content_len - conn->consumed_content;
        if (to_read < (int64_t) len) {
            len = (size_t) to_read;
        }

        // Return buffered data
        body = conn->buf + conn->request_len + conn->consumed_content;
        buffered_len = (int)(&conn->buf[conn->data_len] - body);
        if (buffered_len > 0) {
            if (len < (size_t) buffered_len) {
                buffered_len = (int) len;
            }
            memcpy(buf, body, (size_t) buffered_len);
            len -= buffered_len;
            conn->consumed_content += buffered_len;
            nread += buffered_len;
            buf = (char *) buf + buffered_len;
        }

        // We have returned all buffered data. Read new data from the remote socket.
        n = pull_all(NULL, conn, (char *) buf, (int) len);
        nread = n >= 0 ? nread + n : n;
    }
    return nread;
}

int mg_write(struct mg_connection *conn, const void *buf, size_t len)
{
    time_t now;
    int64_t n, total, allowed;

    if (conn->throttle > 0) {
        if ((now = time(NULL)) != conn->last_throttle_time) {
            conn->last_throttle_time = now;
            conn->last_throttle_bytes = 0;
        }
        allowed = conn->throttle - conn->last_throttle_bytes;
        if (allowed > (int64_t) len) {
            allowed = len;
        }
        if ((total = push(NULL, conn->client.sock, conn->ssl, (const char *) buf,
                          (int64_t) allowed)) == allowed) {
            buf = (char *) buf + total;
            conn->last_throttle_bytes += total;
            while (total < (int64_t) len && conn->ctx->stop_flag == 0) {
                allowed = conn->throttle > (int64_t) len - total ?
                          (int64_t) len - total : conn->throttle;
                if ((n = push(NULL, conn->client.sock, conn->ssl, (const char *) buf,
                              (int64_t) allowed)) != allowed) {
                    break;
                }
                sleep(1);
                conn->last_throttle_bytes = allowed;
                conn->last_throttle_time = time(NULL);
                buf = (char *) buf + n;
                total += n;
            }
        }
    } else {
        total = push(NULL, conn->client.sock, conn->ssl, (const char *) buf,
                     (int64_t) len);
    }
    return (int) total;
}

// Alternative alloc_vprintf() for non-compliant C runtimes
static int alloc_vprintf2(char **buf, const char *fmt, va_list ap)
{
    va_list ap_copy;
    int size = MG_BUF_LEN;
    int len = -1;

    *buf = NULL;
    while (len == -1) {
        if (*buf) free(*buf);
        *buf = (char *)malloc(size *= 4);
        if (!*buf) break;
        va_copy(ap_copy, ap);
        len = vsnprintf(*buf, size, fmt, ap_copy);
        va_end(ap_copy);
    }

    return len;
}

// Print message to buffer. If buffer is large enough to hold the message,
// return buffer. If buffer is to small, allocate large enough buffer on heap,
// and return allocated buffer.
static int alloc_vprintf(char **buf, size_t size, const char *fmt, va_list ap)
{
    va_list ap_copy;
    int len;

    // Windows is not standard-compliant, and vsnprintf() returns -1 if
    // buffer is too small. Also, older versions of msvcrt.dll do not have
    // _vscprintf().  However, if size is 0, vsnprintf() behaves correctly.
    // Therefore, we make two passes: on first pass, get required message length.
    // On second pass, actually print the message.
    va_copy(ap_copy, ap);
    len = vsnprintf(NULL, 0, fmt, ap_copy);
    va_end(ap_copy);

    if (len < 0) {
        // C runtime is not standard compliant, vsnprintf() returned -1.
        // Switch to alternative code path that uses incremental allocations.
        va_copy(ap_copy, ap);
        len = alloc_vprintf2(buf, fmt, ap);
        va_end(ap_copy);
    } else if (len > (int) size &&
               (size = len + 1) > 0 &&
               (*buf = (char *) malloc(size)) == NULL) {
        len = -1;  // Allocation failed, mark failure
    } else {
        va_copy(ap_copy, ap);
        IGNORE_UNUSED_RESULT(vsnprintf(*buf, size, fmt, ap_copy));
        va_end(ap_copy);
    }

    return len;
}

int mg_vprintf(struct mg_connection *conn, const char *fmt, va_list ap);

int mg_vprintf(struct mg_connection *conn, const char *fmt, va_list ap)
{
    char mem[MG_BUF_LEN], *buf = mem;
    int len;

    if ((len = alloc_vprintf(&buf, sizeof(mem), fmt, ap)) > 0) {
        len = mg_write(conn, buf, (size_t) len);
    }
    if (buf != mem && buf != NULL) {
        free(buf);
    }

    return len;
}

int mg_printf(struct mg_connection *conn, const char *fmt, ...)
{
    va_list ap;
    int result;

    va_start(ap, fmt);
    result = mg_vprintf(conn, fmt, ap);
    va_end(ap);

    return result;
}

int mg_url_decode(const char *src, int src_len, char *dst,
                  int dst_len, int is_form_url_encoded)
{
    int i, j, a, b;
#define HEXTOI(x) (isdigit(x) ? x - '0' : x - 'W')

    for (i = j = 0; i < src_len && j < dst_len - 1; i++, j++) {
        if (src[i] == '%' && i < src_len - 2 &&
            isxdigit(* (const unsigned char *) (src + i + 1)) &&
            isxdigit(* (const unsigned char *) (src + i + 2))) {
            a = tolower(* (const unsigned char *) (src + i + 1));
            b = tolower(* (const unsigned char *) (src + i + 2));
            dst[j] = (char) ((HEXTOI(a) << 4) | HEXTOI(b));
            i += 2;
        } else if (is_form_url_encoded && src[i] == '+') {
            dst[j] = ' ';
        } else {
            dst[j] = src[i];
        }
    }

    dst[j] = '\0'; // Null-terminate the destination

    return i >= src_len ? j : -1;
}

int mg_get_var(const char *data, size_t data_len, const char *name,
               char *dst, size_t dst_len)
{
    return mg_get_var2(data,data_len,name,dst,dst_len,0);
}

int mg_get_var2(const char *data, size_t data_len, const char *name,
                char *dst, size_t dst_len, size_t occurrence)
{
    const char *p, *e, *s;
    size_t name_len;
    int len;

    if (dst == NULL || dst_len == 0) {
        len = -2;
    } else if (data == NULL || name == NULL || data_len == 0) {
        len = -1;
        dst[0] = '\0';
    } else {
        name_len = strlen(name);
        e = data + data_len;
        len = -1;
        dst[0] = '\0';

        // data is "var1=val1&var2=val2...". Find variable first
        for (p = data; p + name_len < e; p++) {
            if ((p == data || p[-1] == '&') && p[name_len] == '=' &&
                !mg_strncasecmp(name, p, name_len) && 0 == occurrence--) {

                // Point p to variable value
                p += name_len + 1;

                // Point s to the end of the value
                s = (const char *) memchr(p, '&', (size_t)(e - p));
                if (s == NULL) {
                    s = e;
                }
                assert(s >= p);

                // Decode variable into destination buffer
                len = mg_url_decode(p, (int)(s - p), dst, (int)dst_len, 1);

                // Redirect error code from -1 to -2 (destination buffer too small).
                if (len == -1) {
                    len = -2;
                }
                break;
            }
        }
    }

    return len;
}

int mg_get_cookie(const char *cookie_header, const char *var_name,
                  char *dst, size_t dst_size)
{
    const char *s, *p, *end;
    int name_len, len = -1;

    if (dst == NULL || dst_size == 0) {
        len = -2;
    } else if (var_name == NULL || (s = cookie_header) == NULL) {
        len = -1;
        dst[0] = '\0';
    } else {
        name_len = (int) strlen(var_name);
        end = s + strlen(s);
        dst[0] = '\0';

        for (; (s = mg_strcasestr(s, var_name)) != NULL; s += name_len) {
            if (s[name_len] == '=') {
                s += name_len + 1;
                if ((p = strchr(s, ' ')) == NULL)
                    p = end;
                if (p[-1] == ';')
                    p--;
                if (*s == '"' && p[-1] == '"' && p > s + 1) {
                    s++;
                    p--;
                }
                if ((size_t) (p - s) < dst_size) {
                    len = (int)(p - s);
                    mg_strlcpy(dst, s, (size_t) len + 1);
                } else {
                    len = -3;
                }
                break;
            }
        }
    }
    return len;
}

static void convert_uri_to_file_name(struct mg_connection *conn, char *buf,
                                     size_t buf_len, struct file *filep)
{
    struct vec a, b;
    const char *rewrite, *uri = conn->request_info.uri,
                          *root = conn->ctx->config[DOCUMENT_ROOT];
    char *p;
    int match_len;
    char gz_path[PATH_MAX];
    char const* accept_encoding;

    // Using buf_len - 1 because memmove() for PATH_INFO may shift part
    // of the path one byte on the right.
    // If document_root is NULL, leave the file empty.
    mg_snprintf(conn, buf, buf_len - 1, "%s%s",
                root == NULL ? "" : root,
                root == NULL ? "" : uri);

    rewrite = conn->ctx->config[REWRITE];
    while ((rewrite = next_option(rewrite, &a, &b)) != NULL) {
        if ((match_len = match_prefix(a.ptr, (int) a.len, uri)) > 0) {
            mg_snprintf(conn, buf, buf_len - 1, "%.*s%s", (int) b.len, b.ptr,
                        uri + match_len);
            break;
        }
    }

    if (mg_stat(conn, buf, filep)) return;

    // if we can't find the actual file, look for the file
    // with the same name but a .gz extension. If we find it,
    // use that and set the gzipped flag in the file struct
    // to indicate that the response need to have the content-
    // encoding: gzip header
    // we can only do this if the browser declares support
    if ((accept_encoding = mg_get_header(conn, "Accept-Encoding")) != NULL) {
        if (strstr(accept_encoding,"gzip") != NULL) {
            snprintf(gz_path, sizeof(gz_path), "%s.gz", buf);
            if (mg_stat(conn, gz_path, filep)) {
                filep->gzipped = 1;
                return;
            }
        }
    }

    // Support PATH_INFO for CGI scripts.
    for (p = buf + strlen(buf); p > buf + 1; p--) {
        if (*p == '/') {
            *p = '\0';
            if (match_prefix(conn->ctx->config[CGI_EXTENSIONS],
                             (int)strlen(conn->ctx->config[CGI_EXTENSIONS]), buf) > 0 &&
                mg_stat(conn, buf, filep)) {
                // Shift PATH_INFO block one character right, e.g.
                //  "/x.cgi/foo/bar\x00" => "/x.cgi\x00/foo/bar\x00"
                // conn->path_info is pointing to the local variable "path" declared
                // in handle_request(), so PATH_INFO is not valid after
                // handle_request returns.
                conn->path_info = p + 1;
                memmove(p + 2, p + 1, strlen(p + 1) + 1);  // +1 is for trailing \0
                p[1] = '/';
                break;
            } else {
                *p = '/';
            }
        }
    }
}

// Check whether full request is buffered. Return:
//   -1  if request is malformed
//    0  if request is not yet fully buffered
//   >0  actual request length, including last \r\n\r\n
static int get_request_len(const char *buf, int buflen)
{
    const char *s, *e;
    int len = 0;

    for (s = buf, e = s + buflen - 1; len <= 0 && s < e; s++)
        // Control characters are not allowed but >=128 is.
        if (!isprint(* (const unsigned char *) s) && *s != '\r' &&
            *s != '\n' && * (const unsigned char *) s < 128) {
            len = -1;
            break;  // [i_a] abort scan as soon as one malformed character is found;
            // don't let subsequent \r\n\r\n win us over anyhow
        } else if (s[0] == '\n' && s[1] == '\n') {
            len = (int) (s - buf) + 2;
        } else if (s[0] == '\n' && &s[1] < e &&
                   s[1] == '\r' && s[2] == '\n') {
            len = (int) (s - buf) + 3;
        }

    return len;
}

// Convert month to the month number. Return -1 on error, or month number
static int get_month_index(const char *s)
{
    size_t i;

    for (i = 0; i < ARRAY_SIZE(month_names); i++)
        if (!strcmp(s, month_names[i]))
            return (int) i;

    return -1;
}

static int num_leap_years(int year)
{
    return year / 4 - year / 100 + year / 400;
}

// Parse UTC date-time string, and return the corresponding time_t value.
static time_t parse_date_string(const char *datetime)
{
    static const unsigned short days_before_month[] = {
        0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
    };
    char month_str[32];
    int second, minute, hour, day, month, year, leap_days, days;
    time_t result = (time_t) 0;

    if (((sscanf(datetime, "%d/%3s/%d %d:%d:%d",
                 &day, month_str, &year, &hour, &minute, &second) == 6) ||
         (sscanf(datetime, "%d %3s %d %d:%d:%d",
                 &day, month_str, &year, &hour, &minute, &second) == 6) ||
         (sscanf(datetime, "%*3s, %d %3s %d %d:%d:%d",
                 &day, month_str, &year, &hour, &minute, &second) == 6) ||
         (sscanf(datetime, "%d-%3s-%d %d:%d:%d",
                 &day, month_str, &year, &hour, &minute, &second) == 6)) &&
        year > 1970 &&
        (month = get_month_index(month_str)) != -1) {
        leap_days = num_leap_years(year) - num_leap_years(1970);
        year -= 1970;
        days = year * 365 + days_before_month[month] + (day - 1) + leap_days;
        result = (time_t) days * 24 * 3600 + (time_t) hour * 3600 +
                 minute * 60 + second;
    }

    return result;
}

// Protect against directory disclosure attack by removing '..',
// excessive '/' and '\' characters
static void remove_double_dots_and_double_slashes(char *s)
{
    char *p = s;

    while (*s != '\0') {
        *p++ = *s++;
        if (s[-1] == '/' || s[-1] == '\\') {
            // Skip all following slashes, backslashes and double-dots
            while (s[0] != '\0') {
                if (s[0] == '/' || s[0] == '\\') {
                    s++;
                } else if (s[0] == '.' && s[1] == '.') {
                    s += 2;
                } else {
                    break;
                }
            }
        }
    }
    *p = '\0';
}

static const struct {
    const char *extension;
    size_t ext_len;
    const char *mime_type;
} builtin_mime_types[] = {
    // IANA registered MIME types (http://www.iana.org/assignments/media-types)
    // application types
    {".doc",     4, "application/msword"},
    {".eps",     4, "application/postscript"},
    {".exe",     4, "application/octet-stream"},
    {".js",      3, "application/javascript"},
    {".json",    5, "application/json"},
    {".pdf",     4, "application/pdf"},
    {".ps",      3, "application/postscript"},
    {".rtf",     4, "application/rtf"},
    {".xhtml",   6, "application/xhtml+xml"},
    {".xsl",     4, "application/xml"},
    {".xslt",    5, "application/xml"},

    // audio
    {".mp3",     4, "audio/mpeg"},
    {".oga",     4, "audio/ogg"},
    {".ogg",     4, "audio/ogg"},

    // image
    {".gif",     4, "image/gif"},
    {".ief",     4, "image/ief"},
    {".jpeg",    5, "image/jpeg"},
    {".jpg",     4, "image/jpeg"},
    {".jpm",     4, "image/jpm"},
    {".jpx",     4, "image/jpx"},
    {".png",     4, "image/png"},
    {".svg",     4, "image/svg+xml"},
    {".tif",     4, "image/tiff"},
    {".tiff",    5, "image/tiff"},

    // model
    {".wrl",     4, "model/vrml"},

    // text
    {".css",     4, "text/css"},
    {".csv",     4, "text/csv"},
    {".htm",     4, "text/html"},
    {".html",    5, "text/html"},
    {".sgm",     4, "text/sgml"},
    {".shtm",    5, "text/html"},
    {".shtml",   6, "text/html"},
    {".txt",     4, "text/plain"},
    {".xml",     4, "text/xml"},

    // video
    {".mov",     4, "video/quicktime"},
    {".mp4",     4, "video/mp4"},
    {".mpeg",    5, "video/mpeg"},
    {".mpg",     4, "video/mpeg"},
    {".ogv",     4, "video/ogg"},
    {".qt",      3, "video/quicktime"},

    // not registered types (http://reference.sitepoint.com/html/mime-types-full, http://www.hansenb.pdx.edu/DMKB/dict/tutorials/mime_typ.php, ..)
    {".arj",     4, "application/x-arj-compressed"},
    {".gz",      3, "application/x-gunzip"},
    {".rar",     4, "application/x-arj-compressed"},
    {".swf",     4, "application/x-shockwave-flash"},
    {".tar",     4, "application/x-tar"},
    {".tgz",     4, "application/x-tar-gz"},
    {".torrent", 8, "application/x-bittorrent"},
    {".ppt",     4, "application/x-mspowerpoint"},
    {".xls",     4, "application/x-msexcel"},
    {".zip",     4, "application/x-zip-compressed"},
    {".aac",     4, "audio/aac"}, // http://en.wikipedia.org/wiki/Advanced_Audio_Coding
    {".aif",     4, "audio/x-aif"},
    {".m3u",     4, "audio/x-mpegurl"},
    {".mid",     4, "audio/x-midi"},
    {".ra",      3, "audio/x-pn-realaudio"},
    {".ram",     4, "audio/x-pn-realaudio"},
    {".wav",     4, "audio/x-wav"},
    {".bmp",     4, "image/bmp"},
    {".ico",     4, "image/x-icon"},
    {".pct",     4, "image/x-pct"},
    {".pict",    5, "image/pict"},
    {".rgb",     4, "image/x-rgb"},
    {".webm",    5, "video/webm"}, // http://en.wikipedia.org/wiki/WebM
    {".asf",     4, "video/x-ms-asf"},
    {".avi",     4, "video/x-msvideo"},
    {".m4v",     4, "video/x-m4v"},
    {NULL, 0, NULL}
};

const char *mg_get_builtin_mime_type(const char *path)
{
    const char *ext;
    size_t i, path_len;

    path_len = strlen(path);

    for (i = 0; builtin_mime_types[i].extension != NULL; i++) {
        ext = path + (path_len - builtin_mime_types[i].ext_len);
        if (path_len > builtin_mime_types[i].ext_len &&
            mg_strcasecmp(ext, builtin_mime_types[i].extension) == 0) {
            return builtin_mime_types[i].mime_type;
        }
    }

    return "text/plain";
}

// Look at the "path" extension and figure what mime type it has.
// Store mime type in the vector.
static void get_mime_type(struct mg_context *ctx, const char *path,
                          struct vec *vec)
{
    struct vec ext_vec, mime_vec;
    const char *list, *ext;
    size_t path_len;

    path_len = strlen(path);

    // Scan user-defined mime types first, in case user wants to
    // override default mime types.
    list = ctx->config[EXTRA_MIME_TYPES];
    while ((list = next_option(list, &ext_vec, &mime_vec)) != NULL) {
        // ext now points to the path suffix
        ext = path + path_len - ext_vec.len;
        if (mg_strncasecmp(ext, ext_vec.ptr, ext_vec.len) == 0) {
            *vec = mime_vec;
            return;
        }
    }

    vec->ptr = mg_get_builtin_mime_type(path);
    vec->len = strlen(vec->ptr);
}

// Stringify binary data. Output buffer must be twice as big as input,
// because each byte takes 2 bytes in string representation
static void bin2str(char *to, const unsigned char *p, size_t len)
{
    static const char *hex = "0123456789abcdef";

    for (; len--; p++) {
        *to++ = hex[p[0] >> 4];
        *to++ = hex[p[0] & 0x0f];
    }
    *to = '\0';
}

// Return stringified MD5 hash for list of strings. Buffer must be 33 bytes.
char *mg_md5(char buf[33], ...)
{
    md5_byte_t hash[16];
    const char *p;
    va_list ap;
    md5_state_t ctx;

    md5_init(&ctx);

    va_start(ap, buf);
    while ((p = va_arg(ap, const char *)) != NULL) {
        md5_append(&ctx, (const md5_byte_t *) p, (int) strlen(p));
    }
    va_end(ap);

    md5_finish(&ctx, hash);
    bin2str(buf, hash, sizeof(hash));
    return buf;
}

// Check the user's password, return 1 if OK
static int check_password(const char *method, const char *ha1, const char *uri,
                          const char *nonce, const char *nc, const char *cnonce,
                          const char *qop, const char *response)
{
    char ha2[32 + 1], expected_response[32 + 1];

    // Some of the parameters may be NULL
    if (method == NULL || nonce == NULL || nc == NULL || cnonce == NULL ||
        qop == NULL || response == NULL) {
        return 0;
    }

    // NOTE(lsm): due to a bug in MSIE, we do not compare the URI
    // TODO(lsm): check for authentication timeout
    if (// strcmp(dig->uri, c->ouri) != 0 ||
        strlen(response) != 32
        // || now - strtoul(dig->nonce, NULL, 10) > 3600
    ) {
        return 0;
    }

    mg_md5(ha2, method, ":", uri, NULL);
    mg_md5(expected_response, ha1, ":", nonce, ":", nc,
           ":", cnonce, ":", qop, ":", ha2, NULL);

    return mg_strcasecmp(response, expected_response) == 0;
}

// Use the global passwords file, if specified by auth_gpass option,
// or search for .htpasswd in the requested directory.
static void open_auth_file(struct mg_connection *conn, const char *path,
                           struct file *filep)
{
    char name[PATH_MAX];
    const char *p, *e, *gpass = conn->ctx->config[GLOBAL_PASSWORDS_FILE];
    struct file file = STRUCT_FILE_INITIALIZER;

    if (gpass != NULL) {
        // Use global passwords file
        if (!mg_fopen(conn, gpass, "r", filep)) {
#ifdef DEBUG
            mg_cry(conn, "fopen(%s): %s", gpass, strerror(ERRNO));
#endif
        }
        // Important: using local struct file to test path for is_directory flag.
        // If filep is used, mg_stat() makes it appear as if auth file was opened.
    } else if (mg_stat(conn, path, &file) && file.is_directory) {
        mg_snprintf(conn, name, sizeof(name), "%s%c%s",
                    path, '/', PASSWORDS_FILE_NAME);
        if (!mg_fopen(conn, name, "r", filep)) {
#ifdef DEBUG
            mg_cry(conn, "fopen(%s): %s", name, strerror(ERRNO));
#endif
        }
    } else {
        // Try to find .htpasswd in requested directory.
        for (p = path, e = p + strlen(p) - 1; e > p; e--)
            if (e[0] == '/')
                break;
        mg_snprintf(conn, name, sizeof(name), "%.*s%c%s",
                    (int) (e - p), p, '/', PASSWORDS_FILE_NAME);
        if (!mg_fopen(conn, name, "r", filep)) {
#ifdef DEBUG
            mg_cry(conn, "fopen(%s): %s", name, strerror(ERRNO));
#endif
        }
    }
}

// Parsed Authorization header
struct ah {
    char *user, *uri, *cnonce, *response, *qop, *nc, *nonce;
};

// Return 1 on success. Always initializes the ah structure.
static int parse_auth_header(struct mg_connection *conn, char *buf,
                             size_t buf_size, struct ah *ah)
{
    char *name, *value, *s;
    const char *auth_header;

    (void) memset(ah, 0, sizeof(*ah));
    if ((auth_header = mg_get_header(conn, "Authorization")) == NULL ||
        mg_strncasecmp(auth_header, "Digest ", 7) != 0) {
        return 0;
    }

    // Make modifiable copy of the auth header
    (void) mg_strlcpy(buf, auth_header + 7, buf_size);
    s = buf;

    // Parse authorization header
    for (;;) {
        // Gobble initial spaces
        while (isspace(* (unsigned char *) s)) {
            s++;
        }
        name = skip_quoted(&s, "=", " ", 0);
        // Value is either quote-delimited, or ends at first comma or space.
        if (s[0] == '\"') {
            s++;
            value = skip_quoted(&s, "\"", " ", '\\');
            if (s[0] == ',') {
                s++;
            }
        } else {
            value = skip_quoted(&s, ", ", " ", 0);  // IE uses commas, FF uses spaces
        }
        if (*name == '\0') {
            break;
        }

        if (!strcmp(name, "username")) {
            ah->user = value;
        } else if (!strcmp(name, "cnonce")) {
            ah->cnonce = value;
        } else if (!strcmp(name, "response")) {
            ah->response = value;
        } else if (!strcmp(name, "uri")) {
            ah->uri = value;
        } else if (!strcmp(name, "qop")) {
            ah->qop = value;
        } else if (!strcmp(name, "nc")) {
            ah->nc = value;
        } else if (!strcmp(name, "nonce")) {
            ah->nonce = value;
        }
    }

    // CGI needs it as REMOTE_USER
    if (ah->user != NULL) {
        conn->request_info.remote_user = mg_strdup(ah->user);
    } else {
        return 0;
    }

    return 1;
}

static char *mg_fgets(char *buf, size_t size, struct file *filep, char **p)
{
    char *eof;
    size_t len;
    char *memend;

    if (filep->membuf != NULL && *p != NULL) {
        memend = (char *) &filep->membuf[filep->size];
        eof = (char *) memchr(*p, '\n', memend - *p); // Search for \n from p till the end of stream
        if (eof != NULL) {
            eof += 1; // Include \n
        } else {
            eof = memend; // Copy remaining data
        }
        len = (size_t) (eof - *p) > size - 1 ? size - 1 : (size_t) (eof - *p);
        memcpy(buf, *p, len);
        buf[len] = '\0';
        *p += len;
        return len ? eof : NULL;
    } else if (filep->fp != NULL) {
        return fgets(buf, (int)size, filep->fp);
    } else {
        return NULL;
    }
}

// Authorize against the opened passwords file. Return 1 if authorized.
static int authorize(struct mg_connection *conn, struct file *filep)
{
    struct ah ah;
    char line[256], f_user[256] = "", ha1[256] = "", f_domain[256] = "", buf[MG_BUF_LEN], *p;

    if (!parse_auth_header(conn, buf, sizeof(buf), &ah)) {
        return 0;
    }

    // Loop over passwords file
    p = (char *) filep->membuf;
    while (mg_fgets(line, sizeof(line), filep, &p) != NULL) {
        if (sscanf(line, "%[^:]:%[^:]:%s", f_user, f_domain, ha1) != 3) {
            continue;
        }

        if (!strcmp(ah.user, f_user) &&
            !strcmp(conn->ctx->config[AUTHENTICATION_DOMAIN], f_domain))
            return check_password(conn->request_info.request_method, ha1, ah.uri,
                                  ah.nonce, ah.nc, ah.cnonce, ah.qop, ah.response);
    }

    return 0;
}

// Return 1 if request is authorised, 0 otherwise.
static int check_authorization(struct mg_connection *conn, const char *path)
{
    char fname[PATH_MAX];
    struct vec uri_vec, filename_vec;
    const char *list;
    struct file file = STRUCT_FILE_INITIALIZER;
    int authorized = 1;

    list = conn->ctx->config[PROTECT_URI];
    while ((list = next_option(list, &uri_vec, &filename_vec)) != NULL) {
        if (!memcmp(conn->request_info.uri, uri_vec.ptr, uri_vec.len)) {
            mg_snprintf(conn, fname, sizeof(fname), "%.*s",
                        (int) filename_vec.len, filename_vec.ptr);
            if (!mg_fopen(conn, fname, "r", &file)) {
                mg_cry(conn, "%s: cannot open %s: %s", __func__, fname, strerror(errno));
            }
            break;
        }
    }

    if (!is_file_opened(&file)) {
        open_auth_file(conn, path, &file);
    }

    if (is_file_opened(&file)) {
        authorized = authorize(conn, &file);
        mg_fclose(&file);
    }

    return authorized;
}

static void send_authorization_request(struct mg_connection *conn)
{
    conn->status_code = 401;
    mg_printf(conn,
              "HTTP/1.1 401 Unauthorized\r\n"
              "Content-Length: 0\r\n"
              "WWW-Authenticate: Digest qop=\"auth\", "
              "realm=\"%s\", nonce=\"%lu\"\r\n\r\n",
              conn->ctx->config[AUTHENTICATION_DOMAIN],
              (unsigned long) time(NULL));
}

static int is_authorized_for_put(struct mg_connection *conn)
{
    struct file file = STRUCT_FILE_INITIALIZER;
    const char *passfile = conn->ctx->config[PUT_DELETE_PASSWORDS_FILE];
    int ret = 0;

    if (passfile != NULL && mg_fopen(conn, passfile, "r", &file)) {
        ret = authorize(conn, &file);
        mg_fclose(&file);
    }

    return ret;
}

int mg_modify_passwords_file(const char *fname, const char *domain,
                             const char *user, const char *pass)
{
    int found;
    char line[512], u[512] = "", d[512] ="", ha1[33], tmp[PATH_MAX+1];
    FILE *fp, *fp2;

    found = 0;
    fp = fp2 = NULL;

    // Regard empty password as no password - remove user record.
    if (pass != NULL && pass[0] == '\0') {
        pass = NULL;
    }

    (void) snprintf(tmp, sizeof(tmp) - 1, "%s.tmp", fname);
    tmp[sizeof(tmp) - 1] = 0;

    // Create the file if does not exist
    if ((fp = fopen(fname, "a+")) != NULL) {
        (void) fclose(fp);
    }

    // Open the given file and temporary file
    if ((fp = fopen(fname, "r")) == NULL) {
        return 0;
    } else if ((fp2 = fopen(tmp, "w+")) == NULL) {
        fclose(fp);
        return 0;
    }

    // Copy the stuff to temporary file
    while (fgets(line, sizeof(line), fp) != NULL) {
        if (sscanf(line, "%[^:]:%[^:]:%*s", u, d) != 2) {
            continue;
        }

        if (!strcmp(u, user) && !strcmp(d, domain)) {
            found++;
            if (pass != NULL) {
                mg_md5(ha1, user, ":", domain, ":", pass, NULL);
                fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
            }
        } else {
            fprintf(fp2, "%s", line);
        }
    }

    // If new user, just add it
    if (!found && pass != NULL) {
        mg_md5(ha1, user, ":", domain, ":", pass, NULL);
        fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
    }

    // Close files
    fclose(fp);
    fclose(fp2);

    // Put the temp file in place of real file
    IGNORE_UNUSED_RESULT(remove(fname));
    IGNORE_UNUSED_RESULT(rename(tmp, fname));

    return 1;
}

static SOCKET conn2(struct mg_context *ctx  /* may be null */, const char *host, int port,
                    int use_ssl, char *ebuf, size_t ebuf_len)
{
    struct sockaddr_in sain;
    struct hostent *he;
    SOCKET sock = INVALID_SOCKET;

    if (host == NULL) {
        snprintf(ebuf, ebuf_len, "%s", "NULL host");
    } else if (use_ssl && SSLv23_client_method == NULL) {
        snprintf(ebuf, ebuf_len, "%s", "SSL is not initialized");
        // TODO(lsm): use something threadsafe instead of gethostbyname()
    } else if ((he = gethostbyname(host)) == NULL) {
        snprintf(ebuf, ebuf_len, "gethostbyname(%s): %s", host, strerror(ERRNO));
    } else if ((sock = socket(PF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) {
        snprintf(ebuf, ebuf_len, "socket(): %s", strerror(ERRNO));
    } else {
        set_close_on_exec(sock, fc(ctx));
        memset(&sain, '\0', sizeof(sain));
        sain.sin_family = AF_INET;
        sain.sin_port = htons((uint16_t) port);
        sain.sin_addr = * (struct in_addr *) he->h_addr_list[0];
        if (connect(sock, (struct sockaddr *) &sain, sizeof(sain)) != 0) {
            snprintf(ebuf, ebuf_len, "connect(%s:%d): %s",
                     host, port, strerror(ERRNO));
            closesocket(sock);
            sock = INVALID_SOCKET;
        }
    }
    return sock;
}

int mg_url_encode(const char *src, char *dst, size_t dst_len)
{
    static const char *dont_escape = "._-$,;~()";
    static const char *hex = "0123456789abcdef";
    char *pos = dst;
    const char *end = dst + dst_len - 1;

    for (; *src != '\0' && pos < end; src++, pos++) {
        if (isalnum(*(const unsigned char *) src) ||
            strchr(dont_escape, * (const unsigned char *) src) != NULL) {
            *pos = *src;
        } else if (pos + 2 < end) {
            pos[0] = '%';
            pos[1] = hex[(* (const unsigned char *) src) >> 4];
            pos[2] = hex[(* (const unsigned char *) src) & 0xf];
            pos += 2;
        } else {
            return -1;
        }
    }

    *pos = '\0';
    return (*src == '\0') ? (int)(pos - dst) : -1;
}

static void print_dir_entry(struct de *de)
{
    char size[64], mod[64], href[PATH_MAX];
    struct tm *tm;

    if (de->file.is_directory) {
        mg_snprintf(de->conn, size, sizeof(size), "%s", "[DIRECTORY]");
    } else {
        // We use (signed) cast below because MSVC 6 compiler cannot
        // convert unsigned __int64 to double. Sigh.
        if (de->file.size < 1024) {
            mg_snprintf(de->conn, size, sizeof(size), "%d", (int) de->file.size);
        } else if (de->file.size < 0x100000) {
            mg_snprintf(de->conn, size, sizeof(size),
                        "%.1fk", (double) de->file.size / 1024.0);
        } else if (de->file.size < 0x40000000) {
            mg_snprintf(de->conn, size, sizeof(size),
                        "%.1fM", (double) de->file.size / 1048576);
        } else {
            mg_snprintf(de->conn, size, sizeof(size),
                        "%.1fG", (double) de->file.size / 1073741824);
        }
    }
    tm = localtime(&de->file.modification_time);
    if (tm != NULL) {
        strftime(mod, sizeof(mod), "%d-%b-%Y %H:%M", tm);
    } else {
        strncpy(mod, "01-Jan-1970 00:00", sizeof(mod));
        mod[sizeof(mod) - 1] = '\0';
    }
    mg_url_encode(de->file_name, href, sizeof(href));
    de->conn->num_bytes_sent += mg_printf(de->conn,
                                          "<tr><td><a href=\"%s%s%s\">%s%s</a></td>"
                                          "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
                                          de->conn->request_info.uri, href, de->file.is_directory ? "/" : "",
                                          de->file_name, de->file.is_directory ? "/" : "", mod, size);
}

// This function is called from send_directory() and used for
// sorting directory entries by size, or name, or modification time.
// On windows, __cdecl specification is needed in case if project is built
// with __stdcall convention. qsort always requires __cdels callback.
static int WINCDECL compare_dir_entries(const void *p1, const void *p2)
{
    const struct de *a = (const struct de *) p1, *b = (const struct de *) p2;
    const char *query_string = a->conn->request_info.query_string;
    int cmp_result = 0;

    if (query_string == NULL) {
        query_string = "na";
    }

    if (a->file.is_directory && !b->file.is_directory) {
        return -1;  // Always put directories on top
    } else if (!a->file.is_directory && b->file.is_directory) {
        return 1;   // Always put directories on top
    } else if (*query_string == 'n') {
        cmp_result = strcmp(a->file_name, b->file_name);
    } else if (*query_string == 's') {
        cmp_result = a->file.size == b->file.size ? 0 :
                     a->file.size > b->file.size ? 1 : -1;
    } else if (*query_string == 'd') {
        cmp_result = a->file.modification_time == b->file.modification_time ? 0 :
                     a->file.modification_time > b->file.modification_time ? 1 : -1;
    }

    return query_string[1] == 'd' ? -cmp_result : cmp_result;
}

static int must_hide_file(struct mg_connection *conn, const char *path)
{
    const char *pw_pattern = "**" PASSWORDS_FILE_NAME "$";
    const char *pattern = conn->ctx->config[HIDE_FILES];
    return match_prefix(pw_pattern, (int)strlen(pw_pattern), path) > 0 ||
           (pattern != NULL && match_prefix(pattern, (int)strlen(pattern), path) > 0);
}

static int scan_directory(struct mg_connection *conn, const char *dir,
                          void *data, void (*cb)(struct de *, void *))
{
    char path[PATH_MAX];
    struct dirent *dp;
    DIR *dirp;
    struct de de;

    if ((dirp = opendir(dir)) == NULL) {
        return 0;
    } else {
        de.conn = conn;

        while ((dp = readdir(dirp)) != NULL) {
            // Do not show current dir and hidden files
            if (!strcmp(dp->d_name, ".") ||
                !strcmp(dp->d_name, "..") ||
                must_hide_file(conn, dp->d_name)) {
                continue;
            }

            mg_snprintf(conn, path, sizeof(path), "%s%c%s", dir, '/', dp->d_name);

            // If we don't memset stat structure to zero, mtime will have
            // garbage and strftime() will segfault later on in
            // print_dir_entry(). memset is required only if mg_stat()
            // fails. For more details, see
            // http://code.google.com/p/mongoose/issues/detail?id=79
            memset(&de.file, 0, sizeof(de.file));
            if (!mg_stat(conn, path, &de.file)) {
                mg_cry(conn, "%s: mg_stat(%s) failed: %s",
                       __func__, path, strerror(ERRNO));
            }

            de.file_name = dp->d_name;
            cb(&de, data);
        }
        (void) closedir(dirp);
    }
    return 1;
}

static int remove_directory(struct mg_connection *conn, const char *dir)
{
    char path[PATH_MAX];
    struct dirent *dp;
    DIR *dirp;
    struct de de;

    if ((dirp = opendir(dir)) == NULL) {
        return 0;
    } else {
        de.conn = conn;

        while ((dp = readdir(dirp)) != NULL) {
            // Do not show current dir (but show hidden files as they will also be removed)
            if (!strcmp(dp->d_name, ".") ||
                !strcmp(dp->d_name, "..")) {
                continue;
            }

            mg_snprintf(conn, path, sizeof(path), "%s%c%s", dir, '/', dp->d_name);

            // If we don't memset stat structure to zero, mtime will have
            // garbage and strftime() will segfault later on in
            // print_dir_entry(). memset is required only if mg_stat()
            // fails. For more details, see
            // http://code.google.com/p/mongoose/issues/detail?id=79
            memset(&de.file, 0, sizeof(de.file));
            if (!mg_stat(conn, path, &de.file)) {
                mg_cry(conn, "%s: mg_stat(%s) failed: %s",
                       __func__, path, strerror(ERRNO));
            }
            if(de.file.modification_time) {
                if(de.file.is_directory) {
                    remove_directory(conn, path);
                } else {
                    mg_remove(path);
                }
            }

        }
        (void) closedir(dirp);

        IGNORE_UNUSED_RESULT(rmdir(dir));
    }

    return 1;
}

struct dir_scan_data {
    struct de *entries;
    int num_entries;
    int arr_size;
};

// Behaves like realloc(), but frees original pointer on failure
static void *realloc2(void *ptr, size_t size)
{
    void *new_ptr = realloc(ptr, size);
    if (new_ptr == NULL) {
        free(ptr);
    }
    return new_ptr;
}

static void dir_scan_callback(struct de *de, void *data)
{
    struct dir_scan_data *dsd = (struct dir_scan_data *) data;

    if (dsd->entries == NULL || dsd->num_entries >= dsd->arr_size) {
        dsd->arr_size *= 2;
        dsd->entries = (struct de *) realloc2(dsd->entries, dsd->arr_size *
                                              sizeof(dsd->entries[0]));
    }
    if (dsd->entries == NULL) {
        // TODO(lsm): propagate an error to the caller
        dsd->num_entries = 0;
    } else {
        dsd->entries[dsd->num_entries].file_name = mg_strdup(de->file_name);
        dsd->entries[dsd->num_entries].file = de->file;
        dsd->entries[dsd->num_entries].conn = de->conn;
        dsd->num_entries++;
    }
}

static void handle_directory_request(struct mg_connection *conn,
                                     const char *dir)
{
    int i, sort_direction;
    struct dir_scan_data data = { NULL, 0, 128 };

    if (!scan_directory(conn, dir, &data, dir_scan_callback)) {
        send_http_error(conn, 500, "Cannot open directory",
                        "Error: opendir(%s): %s", dir, strerror(ERRNO));
        return;
    }

    sort_direction = conn->request_info.query_string != NULL &&
                     conn->request_info.query_string[1] == 'd' ? 'a' : 'd';

    conn->must_close = 1;
    mg_printf(conn, "%s",
              "HTTP/1.1 200 OK\r\n"
              "Connection: close\r\n"
              "Content-Type: text/html; charset=utf-8\r\n\r\n");

    conn->num_bytes_sent += mg_printf(conn,
                                      "<html><head><title>Index of %s</title>"
                                      "<style>th {text-align: left;}</style></head>"
                                      "<body><h1>Index of %s</h1><pre><table cellpadding=\"0\">"
                                      "<tr><th><a href=\"?n%c\">Name</a></th>"
                                      "<th><a href=\"?d%c\">Modified</a></th>"
                                      "<th><a href=\"?s%c\">Size</a></th></tr>"
                                      "<tr><td colspan=\"3\"><hr></td></tr>",
                                      conn->request_info.uri, conn->request_info.uri,
                                      sort_direction, sort_direction, sort_direction);

    // Print first entry - link to a parent directory
    conn->num_bytes_sent += mg_printf(conn,
                                      "<tr><td><a href=\"%s%s\">%s</a></td>"
                                      "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
                                      conn->request_info.uri, "..", "Parent directory", "-", "-");

    // Sort and print directory entries
    if (data.entries != NULL) {
        qsort(data.entries, (size_t) data.num_entries,
              sizeof(data.entries[0]), compare_dir_entries);
        for (i = 0; i < data.num_entries; i++) {
            print_dir_entry(&data.entries[i]);
            free(data.entries[i].file_name);
        }
        free(data.entries);
    }

    conn->num_bytes_sent += mg_printf(conn, "%s", "</table></body></html>");
    conn->status_code = 200;
}

// Send len bytes from the opened file to the client.
static void send_file_data(struct mg_connection *conn, struct file *filep,
                           int64_t offset, int64_t len)
{
    char buf[MG_BUF_LEN];
    int to_read, num_read, num_written;

    // Sanity check the offset
    offset = offset < 0 ? 0 : offset > filep->size ? filep->size : offset;

    if (len > 0 && filep->membuf != NULL && filep->size > 0) {
        if (len > filep->size - offset) {
            len = filep->size - offset;
        }
        mg_write(conn, filep->membuf + offset, (size_t) len);
    } else if (len > 0 && filep->fp != NULL) {
        if (offset > 0 && fseeko(filep->fp, offset, SEEK_SET) != 0) {
            mg_cry(conn, "%s: fseeko() failed: %s",
                   __func__, strerror(ERRNO));
        }
        while (len > 0) {
            // Calculate how much to read from the file in the buffer
            to_read = sizeof(buf);
            if ((int64_t) to_read > len) {
                to_read = (int) len;
            }

            // Read from file, exit the loop on error
            if ((num_read = (int) fread(buf, 1, (size_t) to_read, filep->fp)) <= 0) {
                break;
            }

            // Send read bytes to the client, exit the loop on error
            if ((num_written = mg_write(conn, buf, (size_t) num_read)) != num_read) {
                break;
            }

            // Both read and were successful, adjust counters
            conn->num_bytes_sent += num_written;
            len -= num_written;
        }
    }
}

static int parse_range_header(const char *header, int64_t *a, int64_t *b)
{
    return sscanf(header, "bytes=%" INT64_FMT "-%" INT64_FMT, a, b);
}

static void gmt_time_string(char *buf, size_t buf_len, time_t *t)
{
    struct tm *tm;

    tm = gmtime(t);
    if (tm != NULL) {
        strftime(buf, buf_len, "%a, %d %b %Y %H:%M:%S GMT", tm);
    } else {
        strncpy(buf, "Thu, 01 Jan 1970 00:00:00 GMT", buf_len);
        buf[buf_len - 1] = '\0';
    }
}

static void construct_etag(char *buf, size_t buf_len,
                           const struct file *filep)
{
    snprintf(buf, buf_len, "\"%lx.%" INT64_FMT "\"",
             (unsigned long) filep->modification_time, filep->size);
}

static void fclose_on_exec(struct file *filep, struct mg_connection *conn)
{
    if (filep != NULL && filep->fp != NULL) {
#ifdef _WIN32
        (void) conn; /* Unused. */
#else
        if (fcntl(fileno(filep->fp), F_SETFD, FD_CLOEXEC) != 0) {
            mg_cry(conn, "%s: fcntl(F_SETFD FD_CLOEXEC) failed: %s",
                   __func__, strerror(ERRNO));
        }
#endif
    }
}

static void handle_file_request(struct mg_connection *conn, const char *path,
                                struct file *filep)
{
    char date[64], lm[64], etag[64], range[64];
    const char *msg = "OK", *hdr;
    time_t curtime = time(NULL);
    int64_t cl, r1, r2;
    struct vec mime_vec;
    int n;
    char gz_path[PATH_MAX];
    char const* encoding = "";

    get_mime_type(conn->ctx, path, &mime_vec);
    cl = filep->size;
    conn->status_code = 200;
    range[0] = '\0';

    // if this file is in fact a pre-gzipped file, rewrite its filename
    // it's important to rewrite the filename after resolving
    // the mime type from it, to preserve the actual file's type
    if (filep->gzipped) {
        snprintf(gz_path, sizeof(gz_path), "%s.gz", path);
        path = gz_path;
        encoding = "Content-Encoding: gzip\r\n";
    }

    if (!mg_fopen(conn, path, "rb", filep)) {
        send_http_error(conn, 500, http_500_error,
                        "fopen(%s): %s", path, strerror(ERRNO));
        return;
    }

    fclose_on_exec(filep, conn);

    // If Range: header specified, act accordingly
    r1 = r2 = 0;
    hdr = mg_get_header(conn, "Range");
    if (hdr != NULL && (n = parse_range_header(hdr, &r1, &r2)) > 0 &&
        r1 >= 0 && r2 >= 0) {
        // actually, range requests don't play well with a pre-gzipped
        // file (since the range is specified in the uncompressed space)
        if (filep->gzipped) {
            send_http_error(conn, 501, "Not Implemented", "range requests in gzipped files are not supported");
            mg_fclose(filep);
            return;
        }
        conn->status_code = 206;
cl = n == 2 ? (r2 > cl ? cl : r2) - r1 + 1: cl - r1;
        mg_snprintf(conn, range, sizeof(range),
                    "Content-Range: bytes "
                    "%" INT64_FMT "-%"
                    INT64_FMT "/%" INT64_FMT "\r\n",
                    r1, r1 + cl - 1, filep->size);
        msg = "Partial Content";
    }

    // Prepare Etag, Date, Last-Modified headers. Must be in UTC, according to
    // http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3
    gmt_time_string(date, sizeof(date), &curtime);
    gmt_time_string(lm, sizeof(lm), &filep->modification_time);
    construct_etag(etag, sizeof(etag), filep);

    (void) mg_printf(conn,
                     "HTTP/1.1 %d %s\r\n"
                     "Date: %s\r\n"
                     "Last-Modified: %s\r\n"
                     "Etag: %s\r\n"
                     "Content-Type: %.*s\r\n"
                     "Content-Length: %" INT64_FMT "\r\n"
                     "Connection: %s\r\n"
                     "Accept-Ranges: bytes\r\n"
                     "%s%s\r\n",
                     conn->status_code, msg, date, lm, etag, (int) mime_vec.len,
                     mime_vec.ptr, cl, suggest_connection_header(conn), range, encoding);

    if (strcmp(conn->request_info.request_method, "HEAD") != 0) {
        send_file_data(conn, filep, r1, cl);
    }
    mg_fclose(filep);
}

void mg_send_file(struct mg_connection *conn, const char *path)
{
    struct file file = STRUCT_FILE_INITIALIZER;
    if (mg_stat(conn, path, &file)) {
        handle_file_request(conn, path, &file);
    } else {
        send_http_error(conn, 404, "Not Found", "%s", "File not found");
    }
}


// Parse HTTP headers from the given buffer, advance buffer to the point
// where parsing stopped.
static void parse_http_headers(char **buf, struct mg_request_info *ri)
{
    int i;

    for (i = 0; i < (int) ARRAY_SIZE(ri->http_headers); i++) {
        ri->http_headers[i].name = skip_quoted(buf, ":", " ", 0);
        ri->http_headers[i].value = skip(buf, "\r\n");
        if (ri->http_headers[i].name[0] == '\0')
            break;
        ri->num_headers = i + 1;
    }
}

static int is_valid_http_method(const char *method)
{
    return !strcmp(method, "GET") || !strcmp(method, "POST") ||
           !strcmp(method, "HEAD") || !strcmp(method, "CONNECT") ||
           !strcmp(method, "PUT") || !strcmp(method, "DELETE") ||
           !strcmp(method, "OPTIONS") || !strcmp(method, "PROPFIND")
           || !strcmp(method, "MKCOL")
           ;
}

// Parse HTTP request, fill in mg_request_info structure.
// This function modifies the buffer by NUL-terminating
// HTTP request components, header names and header values.
static int parse_http_message(char *buf, int len, struct mg_request_info *ri)
{
    int is_request, request_length = get_request_len(buf, len);
    if (request_length > 0) {
        // Reset attributes. DO NOT TOUCH is_ssl, remote_ip, remote_port
        ri->remote_user = ri->request_method = ri->uri = ri->http_version = NULL;
        ri->num_headers = 0;

        buf[request_length - 1] = '\0';

        // RFC says that all initial whitespaces should be ingored
        while (*buf != '\0' && isspace(* (unsigned char *) buf)) {
            buf++;
        }
        ri->request_method = skip(&buf, " ");
        ri->uri = skip(&buf, " ");
        ri->http_version = skip(&buf, "\r\n");

        // HTTP message could be either HTTP request or HTTP response, e.g.
        // "GET / HTTP/1.0 ...." or  "HTTP/1.0 200 OK ..."
        is_request = is_valid_http_method(ri->request_method);
        if ((is_request && memcmp(ri->http_version, "HTTP/", 5) != 0) ||
            (!is_request && memcmp(ri->request_method, "HTTP/", 5) != 0)) {
            request_length = -1;
        } else {
            if (is_request) {
                ri->http_version += 5;
            }
            parse_http_headers(&buf, ri);
        }
    }
    return request_length;
}

// Keep reading the input (either opened file descriptor fd, or socket sock,
// or SSL descriptor ssl) into buffer buf, until \r\n\r\n appears in the
// buffer (which marks the end of HTTP request). Buffer buf may already
// have some data. The length of the data is stored in nread.
// Upon every read operation, increase nread by the number of bytes read.
static int read_request(FILE *fp, struct mg_connection *conn,
                        char *buf, int bufsiz, int *nread)
{
    int request_len, n = 0;

    request_len = get_request_len(buf, *nread);
    while (conn->ctx->stop_flag == 0 &&
           *nread < bufsiz && request_len == 0 &&
           (n = pull(fp, conn, buf + *nread, bufsiz - *nread)) > 0) {
        *nread += n;
        assert(*nread <= bufsiz);
        request_len = get_request_len(buf, *nread);
    }

    return request_len <= 0 && n <= 0 ? -1 : request_len;
}

// For given directory path, substitute it to valid index file.
// Return 0 if index file has been found, -1 if not found.
// If the file is found, it's stats is returned in stp.
static int substitute_index_file(struct mg_connection *conn, char *path,
                                 size_t path_len, struct file *filep)
{
    const char *list = conn->ctx->config[INDEX_FILES];
    struct file file = STRUCT_FILE_INITIALIZER;
    struct vec filename_vec;
    size_t n = strlen(path);
    int found = 0;

    // The 'path' given to us points to the directory. Remove all trailing
    // directory separator characters from the end of the path, and
    // then append single directory separator character.
    while (n > 0 && path[n - 1] == '/') {
        n--;
    }
    path[n] = '/';

    // Traverse index files list. For each entry, append it to the given
    // path and see if the file exists. If it exists, break the loop
    while ((list = next_option(list, &filename_vec, NULL)) != NULL) {

        // Ignore too long entries that may overflow path buffer
        if (filename_vec.len > path_len - (n + 2))
            continue;

        // Prepare full path to the index file
        mg_strlcpy(path + n + 1, filename_vec.ptr, filename_vec.len + 1);

        // Does it exist?
        if (mg_stat(conn, path, &file)) {
            // Yes it does, break the loop
            *filep = file;
            found = 1;
            break;
        }
    }

    // If no index file exists, restore directory path
    if (!found) {
        path[n] = '\0';
    }

    return found;
}

// Return True if we should reply 304 Not Modified.
static int is_not_modified(const struct mg_connection *conn,
                           const struct file *filep)
{
    char etag[64];
    const char *ims = mg_get_header(conn, "If-Modified-Since");
    const char *inm = mg_get_header(conn, "If-None-Match");
    construct_etag(etag, sizeof(etag), filep);
    return (inm != NULL && !mg_strcasecmp(etag, inm)) ||
           (ims != NULL && filep->modification_time <= parse_date_string(ims));
}

static int forward_body_data(struct mg_connection *conn, FILE *fp,
                             SOCKET sock, SSL *ssl)
{
    const char *expect, *body;
    char buf[MG_BUF_LEN];
    int to_read, nread, buffered_len, success = 0;

    expect = mg_get_header(conn, "Expect");
    assert(fp != NULL);

    if (conn->content_len == -1) {
        send_http_error(conn, 411, "Length Required", "%s", "");
    } else if (expect != NULL && mg_strcasecmp(expect, "100-continue")) {
        send_http_error(conn, 417, "Expectation Failed", "%s", "");
    } else {
        if (expect != NULL) {
            (void) mg_printf(conn, "%s", "HTTP/1.1 100 Continue\r\n\r\n");
        }

        body = conn->buf + conn->request_len + conn->consumed_content;
        buffered_len = (int)(&conn->buf[conn->data_len] - body);
        assert(buffered_len >= 0);
        assert(conn->consumed_content == 0);

        if (buffered_len > 0) {
            if ((int64_t) buffered_len > conn->content_len) {
                buffered_len = (int) conn->content_len;
            }
            push(fp, sock, ssl, body, (int64_t) buffered_len);
            conn->consumed_content += buffered_len;
        }

        nread = 0;
        while (conn->consumed_content < conn->content_len) {
            to_read = sizeof(buf);
            if ((int64_t) to_read > conn->content_len - conn->consumed_content) {
                to_read = (int) (conn->content_len - conn->consumed_content);
            }
            nread = pull(NULL, conn, buf, to_read);
            if (nread <= 0 || push(fp, sock, ssl, buf, nread) != nread) {
                break;
            }
            conn->consumed_content += nread;
        }

        if (conn->consumed_content == conn->content_len) {
            success = nread >= 0;
        }

        // Each error code path in this function must send an error
        if (!success) {
            send_http_error(conn, 577, http_500_error, "%s", "");
        }
    }

    return success;
}

#if !defined(NO_CGI)
// This structure helps to create an environment for the spawned CGI program.
// Environment is an array of "VARIABLE=VALUE\0" ASCIIZ strings,
// last element must be NULL.
// However, on Windows there is a requirement that all these VARIABLE=VALUE\0
// strings must reside in a contiguous buffer. The end of the buffer is
// marked by two '\0' characters.
// We satisfy both worlds: we create an envp array (which is vars), all
// entries are actually pointers inside buf.
struct cgi_env_block {
    struct mg_connection *conn;
    char buf[CGI_ENVIRONMENT_SIZE]; // Environment buffer
    int len; // Space taken
    char *vars[MAX_CGI_ENVIR_VARS]; // char **envp
    int nvars; // Number of variables
};

static char *addenv(struct cgi_env_block *block,
                    PRINTF_FORMAT_STRING(const char *fmt), ...)
PRINTF_ARGS(2, 3);

// Append VARIABLE=VALUE\0 string to the buffer, and add a respective
// pointer into the vars array.
static char *addenv(struct cgi_env_block *block, const char *fmt, ...)
{
    int n, space;
    char *added;
    va_list ap;

    // Calculate how much space is left in the buffer
    space = sizeof(block->buf) - block->len - 2;
    assert(space >= 0);

    // Make a pointer to the free space int the buffer
    added = block->buf + block->len;

    // Copy VARIABLE=VALUE\0 string into the free space
    va_start(ap, fmt);
    n = mg_vsnprintf(block->conn, added, (size_t) space, fmt, ap);
    va_end(ap);

    // Make sure we do not overflow buffer and the envp array
    if (n > 0 && n + 1 < space &&
        block->nvars < (int) ARRAY_SIZE(block->vars) - 2) {
        // Append a pointer to the added string into the envp array
        block->vars[block->nvars++] = added;
        // Bump up used length counter. Include \0 terminator
        block->len += n + 1;
    } else {
        mg_cry(block->conn, "%s: CGI env buffer truncated for [%s]", __func__, fmt);
    }

    return added;
}

static void prepare_cgi_environment(struct mg_connection *conn,
                                    const char *prog,
                                    struct cgi_env_block *blk)
{
    const char *s, *slash;
    struct vec var_vec;
    char *p, src_addr[IP_ADDR_STR_LEN];
    int  i;

    blk->len = blk->nvars = 0;
    blk->conn = conn;
    sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);

    addenv(blk, "SERVER_NAME=%s", conn->ctx->config[AUTHENTICATION_DOMAIN]);
    addenv(blk, "SERVER_ROOT=%s", conn->ctx->config[DOCUMENT_ROOT]);
    addenv(blk, "DOCUMENT_ROOT=%s", conn->ctx->config[DOCUMENT_ROOT]);
    addenv(blk, "SERVER_SOFTWARE=%s/%s", "Civetweb", mg_version());

    // Prepare the environment block
    addenv(blk, "%s", "GATEWAY_INTERFACE=CGI/1.1");
    addenv(blk, "%s", "SERVER_PROTOCOL=HTTP/1.1");
    addenv(blk, "%s", "REDIRECT_STATUS=200"); // For PHP

    // TODO(lsm): fix this for IPv6 case
    addenv(blk, "SERVER_PORT=%d", ntohs(conn->client.lsa.sin.sin_port));

    addenv(blk, "REQUEST_METHOD=%s", conn->request_info.request_method);
    addenv(blk, "REMOTE_ADDR=%s", src_addr);
    addenv(blk, "REMOTE_PORT=%d", conn->request_info.remote_port);
    addenv(blk, "REQUEST_URI=%s", conn->request_info.uri);

    // SCRIPT_NAME
    assert(conn->request_info.uri[0] == '/');
    slash = strrchr(conn->request_info.uri, '/');
    if ((s = strrchr(prog, '/')) == NULL)
        s = prog;
    addenv(blk, "SCRIPT_NAME=%.*s%s", (int) (slash - conn->request_info.uri),
           conn->request_info.uri, s);

    addenv(blk, "SCRIPT_FILENAME=%s", prog);
    addenv(blk, "PATH_TRANSLATED=%s", prog);
    addenv(blk, "HTTPS=%s", conn->ssl == NULL ? "off" : "on");

    if ((s = mg_get_header(conn, "Content-Type")) != NULL)
        addenv(blk, "CONTENT_TYPE=%s", s);

    if (conn->request_info.query_string != NULL)
        addenv(blk, "QUERY_STRING=%s", conn->request_info.query_string);

    if ((s = mg_get_header(conn, "Content-Length")) != NULL)
        addenv(blk, "CONTENT_LENGTH=%s", s);

    if ((s = getenv("PATH")) != NULL)
        addenv(blk, "PATH=%s", s);

    if (conn->path_info != NULL) {
        addenv(blk, "PATH_INFO=%s", conn->path_info);
    }

#if defined(_WIN32)
    if ((s = getenv("COMSPEC")) != NULL) {
        addenv(blk, "COMSPEC=%s", s);
    }
    if ((s = getenv("SYSTEMROOT")) != NULL) {
        addenv(blk, "SYSTEMROOT=%s", s);
    }
    if ((s = getenv("SystemDrive")) != NULL) {
        addenv(blk, "SystemDrive=%s", s);
    }
    if ((s = getenv("ProgramFiles")) != NULL) {
        addenv(blk, "ProgramFiles=%s", s);
    }
    if ((s = getenv("ProgramFiles(x86)")) != NULL) {
        addenv(blk, "ProgramFiles(x86)=%s", s);
    }
#else
    if ((s = getenv("LD_LIBRARY_PATH")) != NULL)
        addenv(blk, "LD_LIBRARY_PATH=%s", s);
#endif // _WIN32

    if ((s = getenv("PERLLIB")) != NULL)
        addenv(blk, "PERLLIB=%s", s);

    if (conn->request_info.remote_user != NULL) {
        addenv(blk, "REMOTE_USER=%s", conn->request_info.remote_user);
        addenv(blk, "%s", "AUTH_TYPE=Digest");
    }

    // Add all headers as HTTP_* variables
    for (i = 0; i < conn->request_info.num_headers; i++) {
        p = addenv(blk, "HTTP_%s=%s",
                   conn->request_info.http_headers[i].name,
                   conn->request_info.http_headers[i].value);

        // Convert variable name into uppercase, and change - to _
        for (; *p != '=' && *p != '\0'; p++) {
            if (*p == '-')
                *p = '_';
            *p = (char) toupper(* (unsigned char *) p);
        }
    }

    // Add user-specified variables
    s = conn->ctx->config[CGI_ENVIRONMENT];
    while ((s = next_option(s, &var_vec, NULL)) != NULL) {
        addenv(blk, "%.*s", (int) var_vec.len, var_vec.ptr);
    }

    blk->vars[blk->nvars++] = NULL;
    blk->buf[blk->len++] = '\0';

    assert(blk->nvars < (int) ARRAY_SIZE(blk->vars));
    assert(blk->len > 0);
    assert(blk->len < (int) sizeof(blk->buf));
}

static void handle_cgi_request(struct mg_connection *conn, const char *prog)
{
    char *buf;
    size_t buflen;
    int headers_len, data_len, i, fdin[2] = { 0, 0 }, fdout[2] = { 0, 0 };
    const char *status, *status_text, *connection_state;
    char *pbuf, dir[PATH_MAX], *p;
    struct mg_request_info ri;
    struct cgi_env_block blk;
    FILE *in = NULL, *out = NULL;
    struct file fout = STRUCT_FILE_INITIALIZER;
    pid_t pid = (pid_t) -1;

    buf = NULL;
    buflen = 16384;
    prepare_cgi_environment(conn, prog, &blk);

    // CGI must be executed in its own directory. 'dir' must point to the
    // directory containing executable program, 'p' must point to the
    // executable program name relative to 'dir'.
    (void) mg_snprintf(conn, dir, sizeof(dir), "%s", prog);
    if ((p = strrchr(dir, '/')) != NULL) {
        *p++ = '\0';
    } else {
        dir[0] = '.', dir[1] = '\0';
        p = (char *) prog;
    }

    if (pipe(fdin) != 0 || pipe(fdout) != 0) {
        send_http_error(conn, 500, http_500_error,
                        "Cannot create CGI pipe: %s", strerror(ERRNO));
        goto done;
    }

    pid = spawn_process(conn, p, blk.buf, blk.vars, fdin[0], fdout[1], dir);
    if (pid == (pid_t) -1) {
        send_http_error(conn, 500, http_500_error,
                        "Cannot spawn CGI process [%s]: %s", prog, strerror(ERRNO));
        goto done;
    }

    // Make sure child closes all pipe descriptors. It must dup them to 0,1
    set_close_on_exec(fdin[0], conn);
    set_close_on_exec(fdin[1], conn);
    set_close_on_exec(fdout[0], conn);
    set_close_on_exec(fdout[1], conn);

    // Parent closes only one side of the pipes.
    // If we don't mark them as closed, close() attempt before
    // return from this function throws an exception on Windows.
    // Windows does not like when closed descriptor is closed again.
    (void) close(fdin[0]);
    (void) close(fdout[1]);
    fdin[0] = fdout[1] = -1;


    if ((in = fdopen(fdin[1], "wb")) == NULL ||
        (out = fdopen(fdout[0], "rb")) == NULL) {
        send_http_error(conn, 500, http_500_error,
                        "fopen: %s", strerror(ERRNO));
        goto done;
    }

    setbuf(in, NULL);
    setbuf(out, NULL);
    fout.fp = out;

    // Send POST data to the CGI process if needed
    if (!strcmp(conn->request_info.request_method, "POST") &&
        !forward_body_data(conn, in, INVALID_SOCKET, NULL)) {
        goto done;
    }

    // Close so child gets an EOF.
    fclose(in);
    in = NULL;
    fdin[1] = -1;

    // Now read CGI reply into a buffer. We need to set correct
    // status code, thus we need to see all HTTP headers first.
    // Do not send anything back to client, until we buffer in all
    // HTTP headers.
    data_len = 0;
    buf = malloc(buflen);
    if (buf == NULL) {
        send_http_error(conn, 500, http_500_error,
                        "Not enough memory for buffer (%u bytes)",
                        (unsigned int) buflen);
        goto done;
    }
    headers_len = read_request(out, conn, buf, (int) buflen, &data_len);
    if (headers_len <= 0) {
        send_http_error(conn, 500, http_500_error,
                        "CGI program sent malformed or too big (>%u bytes) "
                        "HTTP headers: [%.*s]",
                        (unsigned) buflen, data_len, buf);
        goto done;
    }
    pbuf = buf;
    buf[headers_len - 1] = '\0';
    parse_http_headers(&pbuf, &ri);

    // Make up and send the status line
    status_text = "OK";
    if ((status = get_header(&ri, "Status")) != NULL) {
        conn->status_code = atoi(status);
        status_text = status;
        while (isdigit(* (unsigned char *) status_text) || *status_text == ' ') {
            status_text++;
        }
    } else if (get_header(&ri, "Location") != NULL) {
        conn->status_code = 302;
    } else {
        conn->status_code = 200;
    }
    connection_state = get_header(&ri, "Connection");
    if (connection_state == NULL ||
        mg_strcasecmp(connection_state, "keep-alive")) {
        conn->must_close = 1;
    }
    (void) mg_printf(conn, "HTTP/1.1 %d %s\r\n", conn->status_code,
                     status_text);

    // Send headers
    for (i = 0; i < ri.num_headers; i++) {
        mg_printf(conn, "%s: %s\r\n",
                  ri.http_headers[i].name, ri.http_headers[i].value);
    }
    mg_write(conn, "\r\n", 2);

    // Send chunk of data that may have been read after the headers
    conn->num_bytes_sent += mg_write(conn, buf + headers_len,
                                     (size_t)(data_len - headers_len));

    // Read the rest of CGI output and send to the client
    send_file_data(conn, &fout, 0, INT64_MAX);

done:
    if (pid != (pid_t) -1) {
        kill(pid, SIGKILL);
#if !defined(_WIN32)
        {
            int st;
            while (waitpid(pid, &st, 0) != -1);  // clean zombies
        }
#endif
    }
    if (fdin[0] != -1) {
        close(fdin[0]);
    }
    if (fdout[1] != -1) {
        close(fdout[1]);
    }

    if (in != NULL) {
        fclose(in);
    } else if (fdin[1] != -1) {
        close(fdin[1]);
    }

    if (out != NULL) {
        fclose(out);
    } else if (fdout[0] != -1) {
        close(fdout[0]);
    }
    if (buf != NULL) {
        free(buf);
    }
}
#endif // !NO_CGI

// For a given PUT path, create all intermediate subdirectories
// for given path. Return 0 if the path itself is a directory,
// or -1 on error, 1 if OK.
static int put_dir(struct mg_connection *conn, const char *path)
{
    char buf[PATH_MAX];
    const char *s, *p;
    struct file file = STRUCT_FILE_INITIALIZER;
    int len, res = 1;

    for (s = p = path + 2; (p = strchr(s, '/')) != NULL; s = ++p) {
        len = (int)(p - path);
        if (len >= (int) sizeof(buf)) {
            res = -1;
            break;
        }
        memcpy(buf, path, len);
        buf[len] = '\0';

        // Try to create intermediate directory
        DEBUG_TRACE(("mkdir(%s)", buf));
        if (!mg_stat(conn, buf, &file) && mg_mkdir(buf, 0755) != 0) {
            res = -1;
            break;
        }

        // Is path itself a directory?
        if (p[1] == '\0') {
            res = 0;
        }
    }

    return res;
}

static void mkcol(struct mg_connection *conn, const char *path)
{
    int rc, body_len;
    struct de de;
    memset(&de.file, 0, sizeof(de.file));
    if (!mg_stat(conn, path, &de.file)) {
        mg_cry(conn, "%s: mg_stat(%s) failed: %s",
               __func__, path, strerror(ERRNO));
    }

    if(de.file.modification_time) {
        send_http_error(conn, 405, "Method Not Allowed",
                        "mkcol(%s): %s", path, strerror(ERRNO));
        return;
    }

    body_len = conn->data_len - conn->request_len;
    if(body_len > 0) {
        send_http_error(conn, 415, "Unsupported media type",
                        "mkcol(%s): %s", path, strerror(ERRNO));
        return;
    }

    rc = mg_mkdir(path, 0755);

    if (rc == 0) {
        conn->status_code = 201;
        mg_printf(conn, "HTTP/1.1 %d Created\r\n\r\n", conn->status_code);
    } else if (rc == -1) {
        if(errno == EEXIST)
            send_http_error(conn, 405, "Method Not Allowed",
                            "mkcol(%s): %s", path, strerror(ERRNO));
        else if(errno == EACCES)
            send_http_error(conn, 403, "Forbidden",
                            "mkcol(%s): %s", path, strerror(ERRNO));
        else if(errno == ENOENT)
            send_http_error(conn, 409, "Conflict",
                            "mkcol(%s): %s", path, strerror(ERRNO));
        else
            send_http_error(conn, 500, http_500_error,
                            "fopen(%s): %s", path, strerror(ERRNO));
    }
}

static void put_file(struct mg_connection *conn, const char *path)
{
    struct file file = STRUCT_FILE_INITIALIZER;
    const char *range;
    int64_t r1, r2;
    int rc;

    conn->status_code = mg_stat(conn, path, &file) ? 200 : 201;

    if ((rc = put_dir(conn, path)) == 0) {
        mg_printf(conn, "HTTP/1.1 %d OK\r\n\r\n", conn->status_code);
    } else if (rc == -1) {
        send_http_error(conn, 500, http_500_error,
                        "put_dir(%s): %s", path, strerror(ERRNO));
    } else if (!mg_fopen(conn, path, "wb+", &file) || file.fp == NULL) {
        mg_fclose(&file);
        send_http_error(conn, 500, http_500_error,
                        "fopen(%s): %s", path, strerror(ERRNO));
    } else {
        fclose_on_exec(&file, conn);
        range = mg_get_header(conn, "Content-Range");
        r1 = r2 = 0;
        if (range != NULL && parse_range_header(range, &r1, &r2) > 0) {
            conn->status_code = 206;
            fseeko(file.fp, r1, SEEK_SET);
        }
        if (!forward_body_data(conn, file.fp, INVALID_SOCKET, NULL)) {
            conn->status_code = 500;
        }
        mg_printf(conn, "HTTP/1.1 %d OK\r\nContent-Length: 0\r\n\r\n",
                  conn->status_code);
        mg_fclose(&file);
    }
}

static void send_ssi_file(struct mg_connection *, const char *,
                          struct file *, int);

static void do_ssi_include(struct mg_connection *conn, const char *ssi,
                           char *tag, int include_level)
{
    char file_name[MG_BUF_LEN], path[PATH_MAX], *p;
    struct file file = STRUCT_FILE_INITIALIZER;

    // sscanf() is safe here, since send_ssi_file() also uses buffer
    // of size MG_BUF_LEN to get the tag. So strlen(tag) is always < MG_BUF_LEN.
    if (sscanf(tag, " virtual=\"%[^\"]\"", file_name) == 1) {
        // File name is relative to the webserver root
        (void) mg_snprintf(conn, path, sizeof(path), "%s%c%s",
                           conn->ctx->config[DOCUMENT_ROOT], '/', file_name);
    } else if (sscanf(tag, " abspath=\"%[^\"]\"", file_name) == 1) {
        // File name is relative to the webserver working directory
        // or it is absolute system path
        (void) mg_snprintf(conn, path, sizeof(path), "%s", file_name);
    } else if (sscanf(tag, " file=\"%[^\"]\"", file_name) == 1 ||
               sscanf(tag, " \"%[^\"]\"", file_name) == 1) {
        // File name is relative to the currect document
        (void) mg_snprintf(conn, path, sizeof(path), "%s", ssi);
        if ((p = strrchr(path, '/')) != NULL) {
            p[1] = '\0';
        }
        (void) mg_snprintf(conn, path + strlen(path),
                           sizeof(path) - strlen(path), "%s", file_name);
    } else {
        mg_cry(conn, "Bad SSI #include: [%s]", tag);
        return;
    }

    if (!mg_fopen(conn, path, "rb", &file)) {
        mg_cry(conn, "Cannot open SSI #include: [%s]: fopen(%s): %s",
               tag, path, strerror(ERRNO));
    } else {
        fclose_on_exec(&file, conn);
        if (match_prefix(conn->ctx->config[SSI_EXTENSIONS],
                         (int)strlen(conn->ctx->config[SSI_EXTENSIONS]), path) > 0) {
            send_ssi_file(conn, path, &file, include_level + 1);
        } else {
            send_file_data(conn, &file, 0, INT64_MAX);
        }
        mg_fclose(&file);
    }
}

#if !defined(NO_POPEN)
static void do_ssi_exec(struct mg_connection *conn, char *tag)
{
    char cmd[MG_BUF_LEN] = "";
    struct file file = STRUCT_FILE_INITIALIZER;

    if (sscanf(tag, " \"%[^\"]\"", cmd) != 1) {
        mg_cry(conn, "Bad SSI #exec: [%s]", tag);
    } else if ((file.fp = popen(cmd, "r")) == NULL) {
        mg_cry(conn, "Cannot SSI #exec: [%s]: %s", cmd, strerror(ERRNO));
    } else {
        send_file_data(conn, &file, 0, INT64_MAX);
        pclose(file.fp);
    }
}
#endif // !NO_POPEN

static int mg_fgetc(struct file *filep, int offset)
{
    if (filep->membuf != NULL && offset >=0 && offset < filep->size) {
        return ((unsigned char *) filep->membuf)[offset];
    } else if (filep->fp != NULL) {
        return fgetc(filep->fp);
    } else {
        return EOF;
    }
}

static void send_ssi_file(struct mg_connection *conn, const char *path,
                          struct file *filep, int include_level)
{
    char buf[MG_BUF_LEN];
    int ch, offset, len, in_ssi_tag;

    if (include_level > 10) {
        mg_cry(conn, "SSI #include level is too deep (%s)", path);
        return;
    }

    in_ssi_tag = len = offset = 0;
    while ((ch = mg_fgetc(filep, offset)) != EOF) {
        if (in_ssi_tag && ch == '>') {
            in_ssi_tag = 0;
            buf[len++] = (char) ch;
            buf[len] = '\0';
            assert(len <= (int) sizeof(buf));
            if (len < 6 || memcmp(buf, "<!--#", 5) != 0) {
                // Not an SSI tag, pass it
                (void) mg_write(conn, buf, (size_t) len);
            } else {
                if (!memcmp(buf + 5, "include", 7)) {
                    do_ssi_include(conn, path, buf + 12, include_level);
#if !defined(NO_POPEN)
                } else if (!memcmp(buf + 5, "exec", 4)) {
                    do_ssi_exec(conn, buf + 9);
#endif // !NO_POPEN
                } else {
                    mg_cry(conn, "%s: unknown SSI " "command: \"%s\"", path, buf);
                }
            }
            len = 0;
        } else if (in_ssi_tag) {
            if (len == 5 && memcmp(buf, "<!--#", 5) != 0) {
                // Not an SSI tag
                in_ssi_tag = 0;
            } else if (len == (int) sizeof(buf) - 2) {
                mg_cry(conn, "%s: SSI tag is too large", path);
                len = 0;
            }
            buf[len++] = ch & 0xff;
        } else if (ch == '<') {
            in_ssi_tag = 1;
            if (len > 0) {
                mg_write(conn, buf, (size_t) len);
            }
            len = 0;
            buf[len++] = ch & 0xff;
        } else {
            buf[len++] = ch & 0xff;
            if (len == (int) sizeof(buf)) {
                mg_write(conn, buf, (size_t) len);
                len = 0;
            }
        }
    }

    // Send the rest of buffered data
    if (len > 0) {
        mg_write(conn, buf, (size_t) len);
    }
}

static void handle_ssi_file_request(struct mg_connection *conn,
                                    const char *path)
{
    struct file file = STRUCT_FILE_INITIALIZER;

    if (!mg_fopen(conn, path, "rb", &file)) {
        send_http_error(conn, 500, http_500_error, "fopen(%s): %s", path,
                        strerror(ERRNO));
    } else {
        conn->must_close = 1;
        fclose_on_exec(&file, conn);
        mg_printf(conn, "HTTP/1.1 200 OK\r\n"
                  "Content-Type: text/html\r\nConnection: %s\r\n\r\n",
                  suggest_connection_header(conn));
        send_ssi_file(conn, path, &file, 0);
        mg_fclose(&file);
    }
}

static void send_options(struct mg_connection *conn)
{
    conn->status_code = 200;

    mg_printf(conn, "%s", "HTTP/1.1 200 OK\r\n"
              "Allow: GET, POST, HEAD, CONNECT, PUT, DELETE, OPTIONS, PROPFIND, MKCOL\r\n"
              "DAV: 1\r\n\r\n");
}

// Writes PROPFIND properties for a collection element
static void print_props(struct mg_connection *conn, const char* uri,
                        struct file *filep)
{
    char mtime[64];
    gmt_time_string(mtime, sizeof(mtime), &filep->modification_time);
    conn->num_bytes_sent += mg_printf(conn,
                                      "<d:response>"
                                      "<d:href>%s</d:href>"
                                      "<d:propstat>"
                                      "<d:prop>"
                                      "<d:resourcetype>%s</d:resourcetype>"
                                      "<d:getcontentlength>%" INT64_FMT "</d:getcontentlength>"
                                      "<d:getlastmodified>%s</d:getlastmodified>"
                                      "</d:prop>"
                                      "<d:status>HTTP/1.1 200 OK</d:status>"
                                      "</d:propstat>"
                                      "</d:response>\n",
                                      uri,
                                      filep->is_directory ? "<d:collection/>" : "",
                                      filep->size,
                                      mtime);
}

static void print_dav_dir_entry(struct de *de, void *data)
{
    char href[PATH_MAX];
    char href_encoded[PATH_MAX];
    struct mg_connection *conn = (struct mg_connection *) data;
    mg_snprintf(conn, href, sizeof(href), "%s%s",
                conn->request_info.uri, de->file_name);
    mg_url_encode(href, href_encoded, PATH_MAX-1);
    print_props(conn, href_encoded, &de->file);
}

static void handle_propfind(struct mg_connection *conn, const char *path,
                            struct file *filep)
{
    const char *depth = mg_get_header(conn, "Depth");

    conn->must_close = 1;
    conn->status_code = 207;
    mg_printf(conn, "HTTP/1.1 207 Multi-Status\r\n"
              "Connection: close\r\n"
              "Content-Type: text/xml; charset=utf-8\r\n\r\n");

    conn->num_bytes_sent += mg_printf(conn,
                                      "<?xml version=\"1.0\" encoding=\"utf-8\"?>"
                                      "<d:multistatus xmlns:d='DAV:'>\n");

    // Print properties for the requested resource itself
    print_props(conn, conn->request_info.uri, filep);

    // If it is a directory, print directory entries too if Depth is not 0
    if (filep->is_directory &&
        !mg_strcasecmp(conn->ctx->config[ENABLE_DIRECTORY_LISTING], "yes") &&
        (depth == NULL || strcmp(depth, "0") != 0)) {
        scan_directory(conn, path, conn, &print_dav_dir_entry);
    }

    conn->num_bytes_sent += mg_printf(conn, "%s\n", "</d:multistatus>");
}

void mg_lock(struct mg_connection* conn)
{
    (void) pthread_mutex_lock(&conn->mutex);
}

void mg_unlock(struct mg_connection* conn)
{
    (void) pthread_mutex_unlock(&conn->mutex);
}

#if defined(USE_WEBSOCKET)

// START OF SHA-1 code
// Copyright(c) By Steve Reid <steve@edmweb.com>
#define SHA1HANDSOFF
#if defined(__sun)
#include "solarisfixes.h"
#endif

static int is_big_endian(void)
{
    static const int n = 1;
    return ((char *) &n)[0] == 0;
}

union char64long16 {
    unsigned char c[64];
    uint32_t l[16];
};

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

static uint32_t blk0(union char64long16 *block, int i)
{
    // Forrest: SHA expect BIG_ENDIAN, swap if LITTLE_ENDIAN
    if (!is_big_endian()) {
        block->l[i] = (rol(block->l[i], 24) & 0xFF00FF00) |
                      (rol(block->l[i], 8) & 0x00FF00FF);
    }
    return block->l[i];
}

#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
    ^block->l[(i+2)&15]^block->l[i&15],1))
#define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(block, i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
#define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5);w=rol(w,30);
#define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);

typedef struct {
    uint32_t state[5];
    uint32_t count[2];
    unsigned char buffer[64];
} SHA1_CTX;

static void SHA1Transform(uint32_t state[5], const unsigned char buffer[64])
{
    uint32_t a, b, c, d, e;
    union char64long16 block[1];

    memcpy(block, buffer, 64);
    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];
    e = state[4];
    R0(a,b,c,d,e, 0);
    R0(e,a,b,c,d, 1);
    R0(d,e,a,b,c, 2);
    R0(c,d,e,a,b, 3);
    R0(b,c,d,e,a, 4);
    R0(a,b,c,d,e, 5);
    R0(e,a,b,c,d, 6);
    R0(d,e,a,b,c, 7);
    R0(c,d,e,a,b, 8);
    R0(b,c,d,e,a, 9);
    R0(a,b,c,d,e,10);
    R0(e,a,b,c,d,11);
    R0(d,e,a,b,c,12);
    R0(c,d,e,a,b,13);
    R0(b,c,d,e,a,14);
    R0(a,b,c,d,e,15);
    R1(e,a,b,c,d,16);
    R1(d,e,a,b,c,17);
    R1(c,d,e,a,b,18);
    R1(b,c,d,e,a,19);
    R2(a,b,c,d,e,20);
    R2(e,a,b,c,d,21);
    R2(d,e,a,b,c,22);
    R2(c,d,e,a,b,23);
    R2(b,c,d,e,a,24);
    R2(a,b,c,d,e,25);
    R2(e,a,b,c,d,26);
    R2(d,e,a,b,c,27);
    R2(c,d,e,a,b,28);
    R2(b,c,d,e,a,29);
    R2(a,b,c,d,e,30);
    R2(e,a,b,c,d,31);
    R2(d,e,a,b,c,32);
    R2(c,d,e,a,b,33);
    R2(b,c,d,e,a,34);
    R2(a,b,c,d,e,35);
    R2(e,a,b,c,d,36);
    R2(d,e,a,b,c,37);
    R2(c,d,e,a,b,38);
    R2(b,c,d,e,a,39);
    R3(a,b,c,d,e,40);
    R3(e,a,b,c,d,41);
    R3(d,e,a,b,c,42);
    R3(c,d,e,a,b,43);
    R3(b,c,d,e,a,44);
    R3(a,b,c,d,e,45);
    R3(e,a,b,c,d,46);
    R3(d,e,a,b,c,47);
    R3(c,d,e,a,b,48);
    R3(b,c,d,e,a,49);
    R3(a,b,c,d,e,50);
    R3(e,a,b,c,d,51);
    R3(d,e,a,b,c,52);
    R3(c,d,e,a,b,53);
    R3(b,c,d,e,a,54);
    R3(a,b,c,d,e,55);
    R3(e,a,b,c,d,56);
    R3(d,e,a,b,c,57);
    R3(c,d,e,a,b,58);
    R3(b,c,d,e,a,59);
    R4(a,b,c,d,e,60);
    R4(e,a,b,c,d,61);
    R4(d,e,a,b,c,62);
    R4(c,d,e,a,b,63);
    R4(b,c,d,e,a,64);
    R4(a,b,c,d,e,65);
    R4(e,a,b,c,d,66);
    R4(d,e,a,b,c,67);
    R4(c,d,e,a,b,68);
    R4(b,c,d,e,a,69);
    R4(a,b,c,d,e,70);
    R4(e,a,b,c,d,71);
    R4(d,e,a,b,c,72);
    R4(c,d,e,a,b,73);
    R4(b,c,d,e,a,74);
    R4(a,b,c,d,e,75);
    R4(e,a,b,c,d,76);
    R4(d,e,a,b,c,77);
    R4(c,d,e,a,b,78);
    R4(b,c,d,e,a,79);
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
    state[4] += e;
    a = b = c = d = e = 0;
    memset(block, '\0', sizeof(block));
}

static void SHA1Init(SHA1_CTX* context)
{
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
    context->state[4] = 0xC3D2E1F0;
    context->count[0] = context->count[1] = 0;
}

static void SHA1Update(SHA1_CTX* context, const unsigned char* data,
                       uint32_t len)
{
    uint32_t i, j;

    j = context->count[0];
    if ((context->count[0] += len << 3) < j)
        context->count[1]++;
    context->count[1] += (len>>29);
    j = (j >> 3) & 63;
    if ((j + len) > 63) {
        memcpy(&context->buffer[j], data, (i = 64-j));
        SHA1Transform(context->state, context->buffer);
        for ( ; i + 63 < len; i += 64) {
            SHA1Transform(context->state, &data[i]);
        }
        j = 0;
    } else i = 0;
    memcpy(&context->buffer[j], &data[i], len - i);
}

static void SHA1Final(unsigned char digest[20], SHA1_CTX* context)
{
    unsigned i;
    unsigned char finalcount[8], c;

    for (i = 0; i < 8; i++) {
        finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)]
                                         >> ((3-(i & 3)) * 8) ) & 255);
    }
    c = 0200;
    SHA1Update(context, &c, 1);
    while ((context->count[0] & 504) != 448) {
        c = 0000;
        SHA1Update(context, &c, 1);
    }
    SHA1Update(context, finalcount, 8);
    for (i = 0; i < 20; i++) {
        digest[i] = (unsigned char)
                    ((context->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
    }
    memset(context, '\0', sizeof(*context));
    memset(&finalcount, '\0', sizeof(finalcount));
}
// END OF SHA1 CODE

static void base64_encode(const unsigned char *src, int src_len, char *dst)
{
    static const char *b64 =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    int i, j, a, b, c;

    for (i = j = 0; i < src_len; i += 3) {
        a = src[i];
        b = i + 1 >= src_len ? 0 : src[i + 1];
        c = i + 2 >= src_len ? 0 : src[i + 2];

        dst[j++] = b64[a >> 2];
        dst[j++] = b64[((a & 3) << 4) | (b >> 4)];
        if (i + 1 < src_len) {
            dst[j++] = b64[(b & 15) << 2 | (c >> 6)];
        }
        if (i + 2 < src_len) {
            dst[j++] = b64[c & 63];
        }
    }
    while (j % 4 != 0) {
        dst[j++] = '=';
    }
    dst[j++] = '\0';
}

static void send_websocket_handshake(struct mg_connection *conn)
{
    static const char *magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
    char buf[100], sha[20], b64_sha[sizeof(sha) * 2];
    SHA1_CTX sha_ctx;

    mg_snprintf(conn, buf, sizeof(buf), "%s%s",
                mg_get_header(conn, "Sec-WebSocket-Key"), magic);
    SHA1Init(&sha_ctx);
    SHA1Update(&sha_ctx, (unsigned char *) buf, (uint32_t)strlen(buf));
    SHA1Final((unsigned char *) sha, &sha_ctx);
    base64_encode((unsigned char *) sha, sizeof(sha), b64_sha);
    mg_printf(conn, "%s%s%s",
              "HTTP/1.1 101 Switching Protocols\r\n"
              "Upgrade: websocket\r\n"
              "Connection: Upgrade\r\n"
              "Sec-WebSocket-Accept: ", b64_sha, "\r\n\r\n");
}

static void read_websocket(struct mg_connection *conn)
{
    // Pointer to the beginning of the portion of the incoming websocket message queue.
    // The original websocket upgrade request is never removed, so the queue begins after it.
    unsigned char *buf = (unsigned char *) conn->buf + conn->request_len;
    int n;

    // body_len is the length of the entire queue in bytes
    // len is the length of the current message
    // data_len is the length of the current message's data payload
    // header_len is the length of the current message's header
    size_t i, len, mask_len, data_len, header_len, body_len;

    // "The masking key is a 32-bit value chosen at random by the client."
    // http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-17#section-5
    unsigned char mask[4];

    // data points to the place where the message is stored when passed to the websocket_data
    // callback.  This is either mem on the stack, or a dynamically allocated buffer if it is
    // too large.
    char mem[4096];
    char *data = mem;

    // Loop continuously, reading messages from the socket, invoking the callback,
    // and waiting repeatedly until an error occurs.
    assert(conn->content_len == 0);
    for (;;) {
        header_len = 0;
        if ((body_len = conn->data_len - conn->request_len) >= 2) {
            len = buf[1] & 127;
            mask_len = buf[1] & 128 ? 4 : 0;
            if (len < 126 && body_len >= mask_len) {
                data_len = len;
                header_len = 2 + mask_len;
            } else if (len == 126 && body_len >= 4 + mask_len) {
                header_len = 4 + mask_len;
                data_len = ((((int) buf[2]) << 8) + buf[3]);
            } else if (body_len >= 10 + mask_len) {
                header_len = 10 + mask_len;
                data_len = (((uint64_t) ntohl(* (uint32_t *) &buf[2])) << 32) +
                           ntohl(* (uint32_t *) &buf[6]);
            }
        }

        if (header_len > 0) {
            // Allocate space to hold websocket payload
            data = mem;
            if (data_len > sizeof(mem)) {
                data = (char *)malloc(data_len);
                if (data == NULL) {
                    // Allocation failed, exit the loop and then close the connection
                    // TODO: notify user about the failure
                    break;
                }
            }

            // Copy the mask before we shift the queue and destroy it
            if (mask_len > 0) {
                *(uint32_t*)mask = *(uint32_t*)(buf + header_len - mask_len);
            } else {
                *(uint32_t*)mask = 0;
            }

            // Read frame payload from the first message in the queue into data and
            // advance the queue by moving the memory in place.
            assert(body_len >= header_len);
            if (data_len + header_len > body_len) {
                // Overflow case
                len = body_len - header_len;
                memcpy(data, buf + header_len, len);
                // TODO: handle pull error
                pull(NULL, conn, data + len, (int)(data_len - len));
                conn->data_len = 0;
            } else {
                // Length of the message being read at the front of the queue
                len = data_len + header_len;

                // Copy the data payload into the data pointer for the callback
                memcpy(data, buf + header_len, data_len);

                // Move the queue forward len bytes
                memmove(buf, buf + len, body_len - len);

                // Mark the queue as advanced
                conn->data_len -= (int)len;
            }

            // Apply mask if necessary
            if (mask_len > 0) {
                for (i = 0; i < data_len; ++i) {
                    data[i] ^= mask[i & 3];
                }
            }

            // Exit the loop if callback signalled to exit,
            // or "connection close" opcode received.
            if ((conn->ctx->callbacks.websocket_data != NULL &&
                 !conn->ctx->callbacks.websocket_data(conn, buf[0], data, data_len)) ||
                (buf[0] & 0xf) == WEBSOCKET_OPCODE_CONNECTION_CLOSE) {  // Opcode == 8, connection close
                break;
            }

            if (data != mem) {
                free(data);
            }
            // Not breaking the loop, process next websocket frame.
        } else {
            // Read from the socket into the next available location in the message queue.
            if ((n = pull(NULL, conn, conn->buf + conn->data_len,
                          conn->buf_size - conn->data_len)) <= 0) {
                // Error, no bytes read
                break;
            }
            conn->data_len += n;
        }
    }
}

int mg_websocket_write(struct mg_connection* conn, int opcode, const char* data, size_t dataLen)
{
    unsigned char header[10];
    size_t headerLen = 1;

    int retval = -1;

    header[0] = 0x80 + (opcode & 0xF);

    // Frame format: http://tools.ietf.org/html/rfc6455#section-5.2
    if (dataLen < 126) {
        // inline 7-bit length field
        header[1] = (unsigned char)dataLen;
        headerLen = 2;
    } else if (dataLen <= 0xFFFF) {
        // 16-bit length field
        header[1] = 126;
        *(uint16_t*)(header + 2) = htons((uint16_t)dataLen);
        headerLen = 4;
    } else {
        // 64-bit length field
        header[1] = 127;
        *(uint32_t*)(header + 2) = htonl((uint64_t)dataLen >> 32);
        *(uint32_t*)(header + 6) = htonl(dataLen & 0xFFFFFFFF);
        headerLen = 10;
    }

    // Note that POSIX/Winsock's send() is threadsafe
    // http://stackoverflow.com/questions/1981372/are-parallel-calls-to-send-recv-on-the-same-socket-valid
    // but mongoose's mg_printf/mg_write is not (because of the loop in push(), although that is only
    // a problem if the packet is large or outgoing buffer is full).
    (void) mg_lock(conn);
    retval = mg_write(conn, header, headerLen);
    retval = mg_write(conn, data, dataLen);
    mg_unlock(conn);

    return retval;
}

static void handle_websocket_request(struct mg_connection *conn)
{
    const char *version = mg_get_header(conn, "Sec-WebSocket-Version");
    if (version == NULL || strcmp(version, "13") != 0) {
        send_http_error(conn, 426, "Upgrade Required", "%s", "Upgrade Required");
    } else if (conn->ctx->callbacks.websocket_connect != NULL &&
               conn->ctx->callbacks.websocket_connect(conn) != 0) {
        // Callback has returned non-zero, do not proceed with handshake
    } else {
        send_websocket_handshake(conn);
        if (conn->ctx->callbacks.websocket_ready != NULL) {
            conn->ctx->callbacks.websocket_ready(conn);
        }
        read_websocket(conn);
    }
}

static int is_websocket_request(const struct mg_connection *conn)
{
    const char *host, *upgrade, *connection, *version, *key;

    host = mg_get_header(conn, "Host");
    upgrade = mg_get_header(conn, "Upgrade");
    connection = mg_get_header(conn, "Connection");
    key = mg_get_header(conn, "Sec-WebSocket-Key");
    version = mg_get_header(conn, "Sec-WebSocket-Version");

    return host != NULL && upgrade != NULL && connection != NULL &&
           key != NULL && version != NULL &&
           mg_strcasestr(upgrade, "websocket") != NULL &&
           mg_strcasestr(connection, "Upgrade") != NULL;
}
#endif // !USE_WEBSOCKET

static int isbyte(int n)
{
    return n >= 0 && n <= 255;
}

static int parse_net(const char *spec, uint32_t *net, uint32_t *mask)
{
    int n, a, b, c, d, slash = 32, len = 0;

    if ((sscanf(spec, "%d.%d.%d.%d/%d%n", &a, &b, &c, &d, &slash, &n) == 5 ||
         sscanf(spec, "%d.%d.%d.%d%n", &a, &b, &c, &d, &n) == 4) &&
        isbyte(a) && isbyte(b) && isbyte(c) && isbyte(d) &&
        slash >= 0 && slash < 33) {
        len = n;
        *net = ((uint32_t)a << 24) | ((uint32_t)b << 16) | ((uint32_t)c << 8) | d;
        *mask = slash ? 0xffffffffU << (32 - slash) : 0;
    }

    return len;
}

static int set_throttle(const char *spec, uint32_t remote_ip, const char *uri)
{
    int throttle = 0;
    struct vec vec, val;
    uint32_t net, mask;
    char mult;
    double v;

    while ((spec = next_option(spec, &vec, &val)) != NULL) {
        mult = ',';
        if (sscanf(val.ptr, "%lf%c", &v, &mult) < 1 || v < 0 ||
            (lowercase(&mult) != 'k' && lowercase(&mult) != 'm' && mult != ',')) {
            continue;
        }
        v *= lowercase(&mult) == 'k' ? 1024 : lowercase(&mult) == 'm' ? 1048576 : 1;
        if (vec.len == 1 && vec.ptr[0] == '*') {
            throttle = (int) v;
        } else if (parse_net(vec.ptr, &net, &mask) > 0) {
            if ((remote_ip & mask) == net) {
                throttle = (int) v;
            }
        } else if (match_prefix(vec.ptr, (int)vec.len, uri) > 0) {
            throttle = (int) v;
        }
    }

    return throttle;
}

static uint32_t get_remote_ip(const struct mg_connection *conn)
{
    return ntohl(* (uint32_t *) &conn->client.rsa.sin.sin_addr);
}

#ifdef USE_LUA
#include "mod_lua.inl"
#endif // USE_LUA

int mg_upload(struct mg_connection *conn, const char *destination_dir)
{
    const char *content_type_header, *boundary_start;
    char buf[MG_BUF_LEN], path[PATH_MAX], fname[1024], boundary[100], *s;
    FILE *fp;
    int bl, n, i, j, headers_len, boundary_len, eof,
        len = 0, num_uploaded_files = 0;

    // Request looks like this:
    //
    // POST /upload HTTP/1.1
    // Host: 127.0.0.1:8080
    // Content-Length: 244894
    // Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryRVr
    //
    // ------WebKitFormBoundaryRVr
    // Content-Disposition: form-data; name="file"; filename="accum.png"
    // Content-Type: image/png
    //
    //  <89>PNG
    //  <PNG DATA>
    // ------WebKitFormBoundaryRVr

    // Extract boundary string from the Content-Type header
    if ((content_type_header = mg_get_header(conn, "Content-Type")) == NULL ||
        (boundary_start = mg_strcasestr(content_type_header,
                                        "boundary=")) == NULL ||
        (sscanf(boundary_start, "boundary=\"%99[^\"]\"", boundary) == 0 &&
         sscanf(boundary_start, "boundary=%99s", boundary) == 0) ||
        boundary[0] == '\0') {
        return num_uploaded_files;
    }

    boundary_len = (int)strlen(boundary);
    bl = boundary_len + 4;  // \r\n--<boundary>
    for (;;) {
        // Pull in headers
        assert(len >= 0 && len <= (int) sizeof(buf));
        while ((n = mg_read(conn, buf + len, sizeof(buf) - len)) > 0) {
            len += n;
        }
        if ((headers_len = get_request_len(buf, len)) <= 0) {
            break;
        }

        // Fetch file name.
        fname[0] = '\0';
        for (i = j = 0; i < headers_len; i++) {
            if (buf[i] == '\r' && buf[i + 1] == '\n') {
                buf[i] = buf[i + 1] = '\0';
                // TODO(lsm): don't expect filename to be the 3rd field,
                // parse the header properly instead.
                IGNORE_UNUSED_RESULT(sscanf(&buf[j], "Content-Disposition: %*s %*s filename=\"%1023[^\"]",
                                            fname));
                j = i + 2;
            }
        }

        // Give up if the headers are not what we expect
        if (fname[0] == '\0') {
            break;
        }

        // Move data to the beginning of the buffer
        assert(len >= headers_len);
        memmove(buf, &buf[headers_len], len - headers_len);
        len -= headers_len;

        // We open the file with exclusive lock held. This guarantee us
        // there is no other thread can save into the same file simultaneously.
        fp = NULL;
        // Construct destination file name. Do not allow paths to have slashes.
        if ((s = strrchr(fname, '/')) == NULL &&
            (s = strrchr(fname, '\\')) == NULL) {
            s = fname;
        }

        // Open file in binary mode. TODO: set an exclusive lock.
        snprintf(path, sizeof(path), "%s/%s", destination_dir, s);
        if ((fp = fopen(path, "wb")) == NULL) {
            break;
        }

        // Read POST data, write into file until boundary is found.
        eof = n = 0;
        do {
            len += n;
            for (i = 0; i < len - bl; i++) {
                if (!memcmp(&buf[i], "\r\n--", 4) &&
                    !memcmp(&buf[i + 4], boundary, boundary_len)) {
                    // Found boundary, that's the end of file data.
                    fwrite(buf, 1, i, fp);
                    eof = 1;
                    memmove(buf, &buf[i + bl], len - (i + bl));
                    len -= i + bl;
                    break;
                }
            }
            if (!eof && len > bl) {
                fwrite(buf, 1, len - bl, fp);
                memmove(buf, &buf[len - bl], bl);
                len = bl;
            }
        } while (!eof && (n = mg_read(conn, buf + len, sizeof(buf) - len)) > 0);
        fclose(fp);
        if (eof) {
            num_uploaded_files++;
            if (conn->ctx->callbacks.upload != NULL) {
                conn->ctx->callbacks.upload(conn, path);
            }
        }
    }

    return num_uploaded_files;
}

static int is_put_or_delete_request(const struct mg_connection *conn)
{
    const char *s = conn->request_info.request_method;
    return s != NULL && (!strcmp(s, "PUT") ||
                         !strcmp(s, "DELETE") ||
                         !strcmp(s, "MKCOL"));
}

static int get_first_ssl_listener_index(const struct mg_context *ctx)
{
    int i, idx = -1;
    for (i = 0; idx == -1 && i < ctx->num_listening_sockets; i++) {
        idx = ctx->listening_sockets[i].is_ssl ? i : -1;
    }
    return idx;
}

static void redirect_to_https_port(struct mg_connection *conn, int ssl_index)
{
    char host[1025];
    const char *host_header;
    size_t hostlen;

    host_header = mg_get_header(conn, "Host");
    hostlen = sizeof(host);
    if (host_header != NULL) {
        char *pos;

        strncpy(host, host_header, hostlen);
        host[hostlen - 1] = '\0';
        pos = strchr(host, ':');
        if (pos != NULL) {
            *pos = '\0';
        }
    } else {
        // Cannot get host from the Host: header. Fallback to our IP address.
        sockaddr_to_string(host, hostlen, &conn->client.lsa);
    }

    mg_printf(conn, "HTTP/1.1 302 Found\r\nLocation: https://%s:%d%s\r\n\r\n",
              host, (int) ntohs(conn->ctx->listening_sockets[ssl_index].
                                lsa.sin.sin_port), conn->request_info.uri);
}


void mg_set_request_handler(struct mg_context *ctx, const char *uri, mg_request_handler handler, void *cbdata)
{
    struct mg_request_handler_info *tmp_rh, *lastref = 0;
    size_t urilen = strlen(uri);

    // first see it the uri exists
    for (tmp_rh = ctx->request_handlers;
         tmp_rh != NULL && strcmp(uri, tmp_rh->uri);
         lastref = tmp_rh, tmp_rh = tmp_rh->next) {
        // first try for an exact match
        if (urilen == tmp_rh->uri_len && !strcmp(tmp_rh->uri,uri)) {
            // already there...

            if (handler != NULL) {
                // change this entry
                tmp_rh->handler = handler;
                tmp_rh->cbdata = cbdata;
            } else {
                // remove this entry
                if (lastref != NULL)
                    lastref->next = tmp_rh->next;
                else
                    ctx->request_handlers = tmp_rh->next;
                free(tmp_rh->uri);
                free(tmp_rh);
            }
            return;
        }

        // next try for a partial match, we will accept uri/something
        if (tmp_rh->uri_len < urilen
            && uri[tmp_rh->uri_len] == '/'
            && memcmp(tmp_rh->uri, uri, tmp_rh->uri_len) == 0) {
            // if there is a partical match this new entry MUST go BEFORE
            // the current position otherwise it will never be matched.
            break;
        }

    }

    if (handler == NULL) {
        // no handler to set, this was a remove request
        return;
    }

    tmp_rh = (struct mg_request_handler_info *)malloc(sizeof(struct mg_request_handler_info));
    if (tmp_rh == NULL) {
        mg_cry(fc(ctx), "%s", "Cannot create new request handler struct, OOM");
        return;
    }
    tmp_rh->uri = mg_strdup(uri);
    tmp_rh->uri_len = strlen(uri);
    tmp_rh->handler = handler;
    tmp_rh->cbdata = cbdata;

    if (lastref == NULL) {
        tmp_rh->next = ctx->request_handlers;
        ctx->request_handlers = tmp_rh;
    } else {
        tmp_rh->next = lastref->next;
        lastref->next = tmp_rh;
    }

}

static int use_request_handler(struct mg_connection *conn)
{
    struct mg_request_info *request_info = mg_get_request_info(conn);
    const char *uri = request_info->uri;
    size_t urilen = strlen(uri);
    struct mg_request_handler_info *tmp_rh = conn->ctx->request_handlers;

    for (; tmp_rh != NULL; tmp_rh = tmp_rh->next) {

        // first try for an exact match
        if (urilen == tmp_rh->uri_len && !strcmp(tmp_rh->uri,uri)) {
            return tmp_rh->handler(conn, tmp_rh->cbdata);
        }

        // next try for a partial match
        // we will accept uri/something
        if (tmp_rh->uri_len < urilen
            && uri[tmp_rh->uri_len] == '/'
            && memcmp(tmp_rh->uri, uri, tmp_rh->uri_len) == 0) {

            return tmp_rh->handler(conn, tmp_rh->cbdata);
        }

    }

    return 0; // none found
}

// This is the heart of the Civetweb's logic.
// This function is called when the request is read, parsed and validated,
// and Civetweb must decide what action to take: serve a file, or
// a directory, or call embedded function, etcetera.
static void handle_request(struct mg_connection *conn)
{
    struct mg_request_info *ri = &conn->request_info;
    char path[PATH_MAX];
    int uri_len, ssl_index;
    struct file file = STRUCT_FILE_INITIALIZER;

    if ((conn->request_info.query_string = strchr(ri->uri, '?')) != NULL) {
        * ((char *) conn->request_info.query_string++) = '\0';
    }
    uri_len = (int) strlen(ri->uri);
    mg_url_decode(ri->uri, uri_len, (char *) ri->uri, uri_len + 1, 0);
    remove_double_dots_and_double_slashes((char *) ri->uri);
    path[0] = '\0';
    convert_uri_to_file_name(conn, path, sizeof(path), &file);
    conn->throttle = set_throttle(conn->ctx->config[THROTTLE],
                                  get_remote_ip(conn), ri->uri);

    DEBUG_TRACE(("%s", ri->uri));
    // Perform redirect and auth checks before calling begin_request() handler.
    // Otherwise, begin_request() would need to perform auth checks and redirects.
    if (!conn->client.is_ssl && conn->client.ssl_redir &&
        (ssl_index = get_first_ssl_listener_index(conn->ctx)) > -1) {
        redirect_to_https_port(conn, ssl_index);
    } else if (!is_put_or_delete_request(conn) &&
               !check_authorization(conn, path)) {
        send_authorization_request(conn);
    } else if (conn->ctx->callbacks.begin_request != NULL &&
               conn->ctx->callbacks.begin_request(conn)) {
        // Do nothing, callback has served the request
    } else if (conn->ctx->request_handlers != NULL &&
               use_request_handler(conn)) {
        // Do nothing, callback has served the request
#if defined(USE_WEBSOCKET)
    } else if (is_websocket_request(conn)) {
        handle_websocket_request(conn);
#endif
    } else if (!strcmp(ri->request_method, "OPTIONS")) {
        send_options(conn);
    } else if (conn->ctx->config[DOCUMENT_ROOT] == NULL) {
        send_http_error(conn, 404, "Not Found", "Not Found");
    } else if (is_put_or_delete_request(conn) &&
               (is_authorized_for_put(conn) != 1)) {
        send_authorization_request(conn);
    } else if (!strcmp(ri->request_method, "PUT")) {
        put_file(conn, path);
    } else if (!strcmp(ri->request_method, "MKCOL")) {
        mkcol(conn, path);
    } else if (!strcmp(ri->request_method, "DELETE")) {
        struct de de;
        memset(&de.file, 0, sizeof(de.file));
        if(!mg_stat(conn, path, &de.file)) {
            send_http_error(conn, 404, "Not Found", "%s", "File not found");
        } else {
            if(de.file.modification_time) {
                if(de.file.is_directory) {
                    remove_directory(conn, path);
                    send_http_error(conn, 204, "No Content", "%s", "");
                } else if (mg_remove(path) == 0) {
                    send_http_error(conn, 204, "No Content", "%s", "");
                } else {
                    send_http_error(conn, 423, "Locked", "remove(%s): %s", path,
                                    strerror(ERRNO));
                }
            } else {
                send_http_error(conn, 500, http_500_error, "remove(%s): %s", path,
                                strerror(ERRNO));
            }
        }
    } else if ((file.membuf == NULL && file.modification_time == (time_t) 0) ||
               must_hide_file(conn, path)) {
        send_http_error(conn, 404, "Not Found", "%s", "File not found");
    } else if (file.is_directory && ri->uri[uri_len - 1] != '/') {
        mg_printf(conn, "HTTP/1.1 301 Moved Permanently\r\n"
                  "Location: %s/\r\n\r\n", ri->uri);
    } else if (!strcmp(ri->request_method, "PROPFIND")) {
        handle_propfind(conn, path, &file);
    } else if (file.is_directory &&
               !substitute_index_file(conn, path, sizeof(path), &file)) {
        if (!mg_strcasecmp(conn->ctx->config[ENABLE_DIRECTORY_LISTING], "yes")) {
            handle_directory_request(conn, path);
        } else {
            send_http_error(conn, 403, "Directory Listing Denied",
                            "Directory listing denied");
        }
#ifdef USE_LUA
    } else if (match_prefix("**.lp$", 6, path) > 0) {
        handle_lsp_request(conn, path, &file, NULL);
#endif
#if !defined(NO_CGI)
    } else if (match_prefix(conn->ctx->config[CGI_EXTENSIONS],
                            (int)strlen(conn->ctx->config[CGI_EXTENSIONS]),
                            path) > 0) {
        if (strcmp(ri->request_method, "POST") &&
            strcmp(ri->request_method, "HEAD") &&
            strcmp(ri->request_method, "GET")) {
            send_http_error(conn, 501, "Not Implemented",
                            "Method %s is not implemented", ri->request_method);
        } else {
            handle_cgi_request(conn, path);
        }
#endif // !NO_CGI
    } else if (match_prefix(conn->ctx->config[SSI_EXTENSIONS],
                            (int)strlen(conn->ctx->config[SSI_EXTENSIONS]),
                            path) > 0) {
        handle_ssi_file_request(conn, path);
    } else if (is_not_modified(conn, &file)) {
        send_http_error(conn, 304, "Not Modified", "%s", "");
    } else {
        handle_file_request(conn, path, &file);
    }
}

static void close_all_listening_sockets(struct mg_context *ctx)
{
    int i;
    for (i = 0; i < ctx->num_listening_sockets; i++) {
        closesocket(ctx->listening_sockets[i].sock);
    }
    free(ctx->listening_sockets);
}

static int is_valid_port(unsigned int port)
{
    return port < 0xffff;
}

// Valid listening port specification is: [ip_address:]port[s]
// Examples: 80, 443s, 127.0.0.1:3128, 1.2.3.4:8080s
// TODO(lsm): add parsing of the IPv6 address
static int parse_port_string(const struct vec *vec, struct socket *so)
{
    unsigned int a, b, c, d, ch, len, port;
#if defined(USE_IPV6)
    char buf[100];
#endif

    // MacOS needs that. If we do not zero it, subsequent bind() will fail.
    // Also, all-zeroes in the socket address means binding to all addresses
    // for both IPv4 and IPv6 (INADDR_ANY and IN6ADDR_ANY_INIT).
    memset(so, 0, sizeof(*so));
    so->lsa.sin.sin_family = AF_INET;

    if (sscanf(vec->ptr, "%u.%u.%u.%u:%u%n", &a, &b, &c, &d, &port, &len) == 5) {
        // Bind to a specific IPv4 address, e.g. 192.168.1.5:8080
        so->lsa.sin.sin_addr.s_addr = htonl((a << 24) | (b << 16) | (c << 8) | d);
        so->lsa.sin.sin_port = htons((uint16_t) port);
#if defined(USE_IPV6)

    } else if (sscanf(vec->ptr, "[%49[^]]]:%d%n", buf, &port, &len) == 2 &&
               inet_pton(AF_INET6, buf, &so->lsa.sin6.sin6_addr)) {
        // IPv6 address, e.g. [3ffe:2a00:100:7031::1]:8080
        so->lsa.sin6.sin6_family = AF_INET6;
        so->lsa.sin6.sin6_port = htons((uint16_t) port);
#endif
    } else if (sscanf(vec->ptr, "%u%n", &port, &len) == 1) {
        // If only port is specified, bind to IPv4, INADDR_ANY
        so->lsa.sin.sin_port = htons((uint16_t) port);
    } else {
        port = len = 0;   // Parsing failure. Make port invalid.
    }

    ch = vec->ptr[len];  // Next character after the port number
    so->is_ssl = ch == 's';
    so->ssl_redir = ch == 'r';

    // Make sure the port is valid and vector ends with 's', 'r' or ','
    return is_valid_port(port) &&
           (ch == '\0' || ch == 's' || ch == 'r' || ch == ',');
}

static int set_ports_option(struct mg_context *ctx)
{
    const char *list = ctx->config[LISTENING_PORTS];
    int on = 1, success = 1;
#if defined(USE_IPV6)
    int off = 0;
#endif
    struct vec vec;
    struct socket so, *ptr;

    while (success && (list = next_option(list, &vec, NULL)) != NULL) {
        if (!parse_port_string(&vec, &so)) {
            mg_cry(fc(ctx), "%s: %.*s: invalid port spec. Expecting list of: %s",
                   __func__, (int) vec.len, vec.ptr, "[IP_ADDRESS:]PORT[s|r]");
            success = 0;
        } else if (so.is_ssl && ctx->ssl_ctx == NULL) {
            mg_cry(fc(ctx), "Cannot add SSL socket, is -ssl_certificate option set?");
            success = 0;
        } else if ((so.sock = socket(so.lsa.sa.sa_family, SOCK_STREAM, 6)) ==
                   INVALID_SOCKET ||
                   // On Windows, SO_REUSEADDR is recommended only for
                   // broadcast UDP sockets
                   setsockopt(so.sock, SOL_SOCKET, SO_REUSEADDR,
                              (void *) &on, sizeof(on)) != 0 ||
#if defined(USE_IPV6)
                   (so.lsa.sa.sa_family == AF_INET6 &&
                    setsockopt(so.sock, IPPROTO_IPV6, IPV6_V6ONLY, (void *) &off,
                               sizeof(off)) != 0) ||
#endif
                   bind(so.sock, &so.lsa.sa, so.lsa.sa.sa_family == AF_INET ?
                        sizeof(so.lsa.sin) : sizeof(so.lsa)) != 0 ||
                   listen(so.sock, SOMAXCONN) != 0) {
            mg_cry(fc(ctx), "%s: cannot bind to %.*s: %d (%s)", __func__,
                   (int) vec.len, vec.ptr, ERRNO, strerror(errno));
            if (so.sock != INVALID_SOCKET) {
                closesocket(so.sock);
            }
            success = 0;
        } else if ((ptr = (struct socket *) realloc(ctx->listening_sockets,
                          (ctx->num_listening_sockets + 1) *
                          sizeof(ctx->listening_sockets[0]))) == NULL) {
            closesocket(so.sock);
            success = 0;
        } else {
            set_close_on_exec(so.sock, fc(ctx));
            ctx->listening_sockets = ptr;
            ctx->listening_sockets[ctx->num_listening_sockets] = so;
            ctx->num_listening_sockets++;
        }
    }

    if (!success) {
        close_all_listening_sockets(ctx);
    }

    return success;
}

static void log_header(const struct mg_connection *conn, const char *header,
                       FILE *fp)
{
    const char *header_value;

    if ((header_value = mg_get_header(conn, header)) == NULL) {
        (void) fprintf(fp, "%s", " -");
    } else {
        (void) fprintf(fp, " \"%s\"", header_value);
    }
}

static void log_access(const struct mg_connection *conn)
{
    const struct mg_request_info *ri;
    FILE *fp;
    char date[64], src_addr[IP_ADDR_STR_LEN];
    struct tm *tm;

    fp = conn->ctx->config[ACCESS_LOG_FILE] == NULL ?  NULL :
         fopen(conn->ctx->config[ACCESS_LOG_FILE], "a+");

    if (fp == NULL)
        return;

    tm = localtime(&conn->birth_time);
    if (tm != NULL) {
        strftime(date, sizeof(date), "%d/%b/%Y:%H:%M:%S %z", tm);
    } else {
        strncpy(date, "01/Jan/1970:00:00:00 +0000", sizeof(date));
        date[sizeof(date) - 1] = '\0';
    }

    ri = &conn->request_info;
    flockfile(fp);

    sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);
    fprintf(fp, "%s - %s [%s] \"%s %s HTTP/%s\" %d %" INT64_FMT,
            src_addr, ri->remote_user == NULL ? "-" : ri->remote_user, date,
            ri->request_method ? ri->request_method : "-",
            ri->uri ? ri->uri : "-", ri->http_version,
            conn->status_code, conn->num_bytes_sent);
    log_header(conn, "Referer", fp);
    log_header(conn, "User-Agent", fp);
    fputc('\n', fp);
    fflush(fp);

    funlockfile(fp);
    fclose(fp);
}

// Verify given socket address against the ACL.
// Return -1 if ACL is malformed, 0 if address is disallowed, 1 if allowed.
static int check_acl(struct mg_context *ctx, uint32_t remote_ip)
{
    int allowed, flag;
    uint32_t net, mask;
    struct vec vec;
    const char *list = ctx->config[ACCESS_CONTROL_LIST];

    // If any ACL is set, deny by default
    allowed = list == NULL ? '+' : '-';

    while ((list = next_option(list, &vec, NULL)) != NULL) {
        flag = vec.ptr[0];
        if ((flag != '+' && flag != '-') ||
            parse_net(&vec.ptr[1], &net, &mask) == 0) {
            mg_cry(fc(ctx), "%s: subnet must be [+|-]x.x.x.x[/x]", __func__);
            return -1;
        }

        if (net == (remote_ip & mask)) {
            allowed = flag;
        }
    }

    return allowed == '+';
}

#if !defined(_WIN32)
static int set_uid_option(struct mg_context *ctx)
{
    struct passwd *pw;
    const char *uid = ctx->config[RUN_AS_USER];
    int success = 0;

    if (uid == NULL) {
        success = 1;
    } else {
        if ((pw = getpwnam(uid)) == NULL) {
            mg_cry(fc(ctx), "%s: unknown user [%s]", __func__, uid);
        } else if (setgid(pw->pw_gid) == -1) {
            mg_cry(fc(ctx), "%s: setgid(%s): %s", __func__, uid, strerror(errno));
        } else if (setuid(pw->pw_uid) == -1) {
            mg_cry(fc(ctx), "%s: setuid(%s): %s", __func__, uid, strerror(errno));
        } else {
            success = 1;
        }
    }

    return success;
}
#endif // !_WIN32

#if !defined(NO_SSL)
static pthread_mutex_t *ssl_mutexes;

static int sslize(struct mg_connection *conn, SSL_CTX *s, int (*func)(SSL *))
{
    return (conn->ssl = SSL_new(s)) != NULL &&
           SSL_set_fd(conn->ssl, conn->client.sock) == 1 &&
           func(conn->ssl) == 1;
}

// Return OpenSSL error message
static const char *ssl_error(void)
{
    unsigned long err;
    err = ERR_get_error();
    return err == 0 ? "" : ERR_error_string(err, NULL);
}

static void ssl_locking_callback(int mode, int mutex_num, const char *file,
                                 int line)
{
    (void) line;
    (void) file;

    if (mode & 1) {  // 1 is CRYPTO_LOCK
        (void) pthread_mutex_lock(&ssl_mutexes[mutex_num]);
    } else {
        (void) pthread_mutex_unlock(&ssl_mutexes[mutex_num]);
    }
}

static unsigned long ssl_id_callback(void)
{
    return (unsigned long) pthread_self();
}

#if !defined(NO_SSL_DL)
static void *load_dll(struct mg_context *ctx, const char *dll_name,
                      struct ssl_func *sw)
{
    union {
        void *p;
        void (*fp)(void);
    } u;
    void  *dll_handle;
    struct ssl_func *fp;

    if ((dll_handle = dlopen(dll_name, RTLD_LAZY)) == NULL) {
        mg_cry(fc(ctx), "%s: cannot load %s", __func__, dll_name);
        return NULL;
    }

    for (fp = sw; fp->name != NULL; fp++) {
#ifdef _WIN32
        // GetProcAddress() returns pointer to function
        u.fp = (void (*)(void)) dlsym(dll_handle, fp->name);
#else
        // dlsym() on UNIX returns void *. ISO C forbids casts of data pointers to
        // function pointers. We need to use a union to make a cast.
        u.p = dlsym(dll_handle, fp->name);
#endif // _WIN32
        if (u.fp == NULL) {
            mg_cry(fc(ctx), "%s: %s: cannot find %s", __func__, dll_name, fp->name);
            dlclose(dll_handle);
            return NULL;
        } else {
            fp->ptr = u.fp;
        }
    }

    return dll_handle;
}
#endif // NO_SSL_DL

// Dynamically load SSL library. Set up ctx->ssl_ctx pointer.
static int set_ssl_option(struct mg_context *ctx)
{
    int i, size;
    const char *pem;

    // If PEM file is not specified and the init_ssl callback
    // is not specified, skip SSL initialization.
    if ((pem = ctx->config[SSL_CERTIFICATE]) == NULL &&
        ctx->callbacks.init_ssl == NULL) {
        return 1;
    }

#if !defined(NO_SSL_DL)
    ctx->ssllib_dll_handle = load_dll(ctx, SSL_LIB, ssl_sw);
    ctx->cryptolib_dll_handle = load_dll(ctx, CRYPTO_LIB, crypto_sw);
    if (!ctx->ssllib_dll_handle || !ctx->cryptolib_dll_handle) {
        return 0;
    }
#endif // NO_SSL_DL

    // Initialize SSL library
    SSL_library_init();
    SSL_load_error_strings();

    if ((ctx->ssl_ctx = SSL_CTX_new(SSLv23_server_method())) == NULL) {
        mg_cry(fc(ctx), "SSL_CTX_new (server) error: %s", ssl_error());
        return 0;
    }

    // If user callback returned non-NULL, that means that user callback has
    // set up certificate itself. In this case, skip sertificate setting.
    if ((ctx->callbacks.init_ssl == NULL ||
         !ctx->callbacks.init_ssl(ctx->ssl_ctx, ctx->user_data)) &&
        (SSL_CTX_use_certificate_file(ctx->ssl_ctx, pem, 1) == 0 ||
         SSL_CTX_use_PrivateKey_file(ctx->ssl_ctx, pem, 1) == 0)) {
        mg_cry(fc(ctx), "%s: cannot open %s: %s", __func__, pem, ssl_error());
        return 0;
    }

    if (pem != NULL) {
        (void) SSL_CTX_use_certificate_chain_file(ctx->ssl_ctx, pem);
    }

    // Initialize locking callbacks, needed for thread safety.
    // http://www.openssl.org/support/faq.html#PROG1
    size = sizeof(pthread_mutex_t) * CRYPTO_num_locks();
    if ((ssl_mutexes = (pthread_mutex_t *) malloc((size_t)size)) == NULL) {
        mg_cry(fc(ctx), "%s: cannot allocate mutexes: %s", __func__, ssl_error());
        return 0;
    }

    for (i = 0; i < CRYPTO_num_locks(); i++) {
        pthread_mutex_init(&ssl_mutexes[i], NULL);
    }

    CRYPTO_set_locking_callback(&ssl_locking_callback);
    CRYPTO_set_id_callback(&ssl_id_callback);

    return 1;
}

static void uninitialize_ssl(struct mg_context *ctx)
{
    int i;
    if (ctx->ssl_ctx != NULL) {
        CRYPTO_set_locking_callback(NULL);
        for (i = 0; i < CRYPTO_num_locks(); i++) {
            pthread_mutex_destroy(&ssl_mutexes[i]);
        }
        CRYPTO_set_locking_callback(NULL);
        CRYPTO_set_id_callback(NULL);
    }
}
#endif // !NO_SSL

static int set_gpass_option(struct mg_context *ctx)
{
    struct file file = STRUCT_FILE_INITIALIZER;
    const char *path = ctx->config[GLOBAL_PASSWORDS_FILE];
    if (path != NULL && !mg_stat(fc(ctx), path, &file)) {
        mg_cry(fc(ctx), "Cannot open %s: %s", path, strerror(ERRNO));
        return 0;
    }
    return 1;
}

static int set_acl_option(struct mg_context *ctx)
{
    return check_acl(ctx, (uint32_t) 0x7f000001UL) != -1;
}

static void reset_per_request_attributes(struct mg_connection *conn)
{
    conn->path_info = NULL;
    conn->num_bytes_sent = conn->consumed_content = 0;
    conn->status_code = -1;
    conn->must_close = conn->request_len = conn->throttle = 0;
}

static void close_socket_gracefully(struct mg_connection *conn)
{
#if defined(_WIN32)
    char buf[MG_BUF_LEN];
    int n;
#endif
    struct linger linger;

    // Set linger option to avoid socket hanging out after close. This prevent
    // ephemeral port exhaust problem under high QPS.
    linger.l_onoff = 1;
    linger.l_linger = 1;
    if (setsockopt(conn->client.sock, SOL_SOCKET, SO_LINGER,
                   (char *) &linger, sizeof(linger)) != 0) {
        mg_cry(conn, "%s: setsockopt(SOL_SOCKET SO_LINGER) failed: %s",
               __func__, strerror(ERRNO));
    }

    // Send FIN to the client
    shutdown(conn->client.sock, SHUT_WR);
    set_non_blocking_mode(conn->client.sock);

#if defined(_WIN32)
    // Read and discard pending incoming data. If we do not do that and close the
    // socket, the data in the send buffer may be discarded. This
    // behaviour is seen on Windows, when client keeps sending data
    // when server decides to close the connection; then when client
    // does recv() it gets no data back.
    do {
        n = pull(NULL, conn, buf, sizeof(buf));
    } while (n > 0);
#endif

    // Now we know that our FIN is ACK-ed, safe to close
    closesocket(conn->client.sock);
}

static void close_connection(struct mg_connection *conn)
{
    // call the connection_close callback if assigned
    if (conn->ctx->callbacks.connection_close != NULL)
        conn->ctx->callbacks.connection_close(conn);

    mg_lock(conn);

    conn->must_close = 1;

#ifndef NO_SSL
    if (conn->ssl != NULL) {
        // Run SSL_shutdown twice to ensure completly close SSL connection
        SSL_shutdown(conn->ssl);
        SSL_free(conn->ssl);
        conn->ssl = NULL;
    }
#endif
    if (conn->client.sock != INVALID_SOCKET) {
        close_socket_gracefully(conn);
        conn->client.sock = INVALID_SOCKET;
    }

    mg_unlock(conn);
}

void mg_close_connection(struct mg_connection *conn)
{
#ifndef NO_SSL
    if (conn->client_ssl_ctx != NULL) {
        SSL_CTX_free((SSL_CTX *) conn->client_ssl_ctx);
    }
#endif
    close_connection(conn);
    (void) pthread_mutex_destroy(&conn->mutex);
    free(conn);
}

struct mg_connection *mg_connect(const char *host, int port, int use_ssl,
                                 char *ebuf, size_t ebuf_len);

struct mg_connection *mg_connect(const char *host, int port, int use_ssl,
                                 char *ebuf, size_t ebuf_len)
{
    static struct mg_context fake_ctx;
    struct mg_connection *conn = NULL;
    SOCKET sock;

    if ((sock = conn2(&fake_ctx, host, port, use_ssl, ebuf,
                      ebuf_len)) == INVALID_SOCKET) {
    } else if ((conn = (struct mg_connection *)
                       calloc(1, sizeof(*conn) + MAX_REQUEST_SIZE)) == NULL) {
        snprintf(ebuf, ebuf_len, "calloc(): %s", strerror(ERRNO));
        closesocket(sock);
#ifndef NO_SSL
    } else if (use_ssl && (conn->client_ssl_ctx =
                               SSL_CTX_new(SSLv23_client_method())) == NULL) {
        snprintf(ebuf, ebuf_len, "SSL_CTX_new error");
        closesocket(sock);
        free(conn);
        conn = NULL;
#endif // NO_SSL
    } else {
        socklen_t len = sizeof(struct sockaddr);
        conn->buf_size = MAX_REQUEST_SIZE;
        conn->buf = (char *) (conn + 1);
        conn->ctx = &fake_ctx;
        conn->client.sock = sock;
        if (getsockname(sock, &conn->client.rsa.sa, &len) != 0) {
            mg_cry(conn, "%s: getsockname() failed: %s",
                   __func__, strerror(ERRNO));
        }
        conn->client.is_ssl = use_ssl;
        (void) pthread_mutex_init(&conn->mutex, NULL);
#ifndef NO_SSL
        if (use_ssl) {
            // SSL_CTX_set_verify call is needed to switch off server certificate
            // checking, which is off by default in OpenSSL and on in yaSSL.
            SSL_CTX_set_verify(conn->client_ssl_ctx, 0, 0);
            sslize(conn, conn->client_ssl_ctx, SSL_connect);
        }
#endif
    }

    return conn;
}

static int is_valid_uri(const char *uri)
{
    // Conform to http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.1.2
    // URI can be an asterisk (*) or should start with slash.
    return uri[0] == '/' || (uri[0] == '*' && uri[1] == '\0');
}

static int getreq(struct mg_connection *conn, char *ebuf, size_t ebuf_len)
{
    const char *cl;

    ebuf[0] = '\0';
    reset_per_request_attributes(conn);
    conn->request_len = read_request(NULL, conn, conn->buf, conn->buf_size,
                                     &conn->data_len);
    assert(conn->request_len < 0 || conn->data_len >= conn->request_len);

    if (conn->request_len == 0 && conn->data_len == conn->buf_size) {
        snprintf(ebuf, ebuf_len, "%s", "Request Too Large");
    } else if (conn->request_len <= 0) {
        snprintf(ebuf, ebuf_len, "%s", "Client closed connection");
    } else if (parse_http_message(conn->buf, conn->buf_size,
                                  &conn->request_info) <= 0) {
        snprintf(ebuf, ebuf_len, "Bad request: [%.*s]", conn->data_len, conn->buf);
    } else {
        // Request is valid
        if ((cl = get_header(&conn->request_info, "Content-Length")) != NULL) {
            conn->content_len = strtoll(cl, NULL, 10);
        } else if (!mg_strcasecmp(conn->request_info.request_method, "POST") ||
                   !mg_strcasecmp(conn->request_info.request_method, "PUT")) {
            conn->content_len = -1;
        } else {
            conn->content_len = 0;
        }
        conn->birth_time = time(NULL);
    }
    return ebuf[0] == '\0';
}

struct mg_connection *mg_download(const char *host, int port, int use_ssl,
                                  char *ebuf, size_t ebuf_len,
                                  const char *fmt, ...)
{
    struct mg_connection *conn;
    va_list ap;

    va_start(ap, fmt);
    ebuf[0] = '\0';
    if ((conn = mg_connect(host, port, use_ssl, ebuf, ebuf_len)) == NULL) {
    } else if (mg_vprintf(conn, fmt, ap) <= 0) {
        snprintf(ebuf, ebuf_len, "%s", "Error sending request");
    } else {
        getreq(conn, ebuf, ebuf_len);
    }
    if (ebuf[0] != '\0' && conn != NULL) {
        mg_close_connection(conn);
        conn = NULL;
    }
    va_end(ap);

    return conn;
}

static void process_new_connection(struct mg_connection *conn)
{
    struct mg_request_info *ri = &conn->request_info;
    int keep_alive_enabled, keep_alive, discard_len;
    char ebuf[100];

    keep_alive_enabled = !strcmp(conn->ctx->config[ENABLE_KEEP_ALIVE], "yes");
    keep_alive = 0;

    // Important: on new connection, reset the receiving buffer. Credit goes
    // to crule42.
    conn->data_len = 0;
    do {
        if (!getreq(conn, ebuf, sizeof(ebuf))) {
            send_http_error(conn, 500, "Server Error", "%s", ebuf);
            conn->must_close = 1;
        } else if (!is_valid_uri(conn->request_info.uri)) {
            snprintf(ebuf, sizeof(ebuf), "Invalid URI: [%s]", ri->uri);
            send_http_error(conn, 400, "Bad Request", "%s", ebuf);
        } else if (strcmp(ri->http_version, "1.0") &&
                   strcmp(ri->http_version, "1.1")) {
            snprintf(ebuf, sizeof(ebuf), "Bad HTTP version: [%s]", ri->http_version);
            send_http_error(conn, 505, "Bad HTTP version", "%s", ebuf);
        }

        if (ebuf[0] == '\0') {
            handle_request(conn);
            if (conn->ctx->callbacks.end_request != NULL) {
                conn->ctx->callbacks.end_request(conn, conn->status_code);
            }
            log_access(conn);
        }
        if (ri->remote_user != NULL) {
            free((void *) ri->remote_user);
            // Important! When having connections with and without auth
            // would cause double free and then crash
            ri->remote_user = NULL;
        }

        // NOTE(lsm): order is important here. should_keep_alive() call
        // is using parsed request, which will be invalid after memmove's below.
        // Therefore, memorize should_keep_alive() result now for later use
        // in loop exit condition.
        keep_alive = conn->ctx->stop_flag == 0 && keep_alive_enabled &&
                     conn->content_len >= 0 && should_keep_alive(conn);

        // Discard all buffered data for this request
        discard_len = conn->content_len >= 0 && conn->request_len > 0 &&
                      conn->request_len + conn->content_len < (int64_t) conn->data_len ?
                      (int) (conn->request_len + conn->content_len) : conn->data_len;
        assert(discard_len >= 0);
        memmove(conn->buf, conn->buf + discard_len, conn->data_len - discard_len);
        conn->data_len -= discard_len;
        assert(conn->data_len >= 0);
        assert(conn->data_len <= conn->buf_size);
    } while (keep_alive);
}

// Worker threads take accepted socket from the queue
static int consume_socket(struct mg_context *ctx, struct socket *sp)
{
    (void) pthread_mutex_lock(&ctx->mutex);
    DEBUG_TRACE(("going idle"));

    // If the queue is empty, wait. We're idle at this point.
    while (ctx->sq_head == ctx->sq_tail && ctx->stop_flag == 0) {
        pthread_cond_wait(&ctx->sq_full, &ctx->mutex);
    }

    // If we're stopping, sq_head may be equal to sq_tail.
    if (ctx->sq_head > ctx->sq_tail) {
        // Copy socket from the queue and increment tail
        *sp = ctx->queue[ctx->sq_tail % ARRAY_SIZE(ctx->queue)];
        ctx->sq_tail++;
        DEBUG_TRACE(("grabbed socket %d, going busy", sp->sock));

        // Wrap pointers if needed
        while (ctx->sq_tail > (int) ARRAY_SIZE(ctx->queue)) {
            ctx->sq_tail -= ARRAY_SIZE(ctx->queue);
            ctx->sq_head -= ARRAY_SIZE(ctx->queue);
        }
    }

    (void) pthread_cond_signal(&ctx->sq_empty);
    (void) pthread_mutex_unlock(&ctx->mutex);

    return !ctx->stop_flag;
}

static void *worker_thread_run(void *thread_func_param)
{
    struct mg_context *ctx = (struct mg_context *) thread_func_param;
    struct mg_connection *conn;

    conn = (struct mg_connection *) calloc(1, sizeof(*conn) + MAX_REQUEST_SIZE);
    if (conn == NULL) {
        mg_cry(fc(ctx), "%s", "Cannot create new connection struct, OOM");
    } else {
        conn->buf_size = MAX_REQUEST_SIZE;
        conn->buf = (char *) (conn + 1);
        conn->ctx = ctx;
        conn->request_info.user_data = ctx->user_data;
        // Allocate a mutex for this connection to allow communication both
        // within the request handler and from elsewhere in the application
        (void) pthread_mutex_init(&conn->mutex, NULL);

        // Call consume_socket() even when ctx->stop_flag > 0, to let it signal
        // sq_empty condvar to wake up the master waiting in produce_socket()
        while (consume_socket(ctx, &conn->client)) {
            conn->birth_time = time(NULL);

            // Fill in IP, port info early so even if SSL setup below fails,
            // error handler would have the corresponding info.
            // Thanks to Johannes Winkelmann for the patch.
            // TODO(lsm): Fix IPv6 case
            conn->request_info.remote_port = ntohs(conn->client.rsa.sin.sin_port);
            memcpy(&conn->request_info.remote_ip,
                   &conn->client.rsa.sin.sin_addr.s_addr, 4);
            conn->request_info.remote_ip = ntohl(conn->request_info.remote_ip);
            conn->request_info.is_ssl = conn->client.is_ssl;

            if (!conn->client.is_ssl
#ifndef NO_SSL
                || sslize(conn, conn->ctx->ssl_ctx, SSL_accept)
#endif
               ) {
                process_new_connection(conn);
            }

            close_connection(conn);
        }
        free(conn);
    }

    // Signal master that we're done with connection and exiting
    (void) pthread_mutex_lock(&ctx->mutex);
    ctx->num_threads--;
    (void) pthread_cond_signal(&ctx->cond);
    assert(ctx->num_threads >= 0);
    (void) pthread_mutex_unlock(&ctx->mutex);

    DEBUG_TRACE(("exiting"));
    return NULL;
}

/* Threads have different return types on Windows and Unix. */

#ifdef _WIN32
static unsigned __stdcall worker_thread(void *thread_func_param)
{
    worker_thread_run(thread_func_param);
    return 0;
}
#else
static void *worker_thread(void *thread_func_param)
{
    worker_thread_run(thread_func_param);
    return NULL;
}
#endif /* _WIN32 */

// Master thread adds accepted socket to a queue
static void produce_socket(struct mg_context *ctx, const struct socket *sp)
{
    (void) pthread_mutex_lock(&ctx->mutex);

    // If the queue is full, wait
    while (ctx->stop_flag == 0 &&
           ctx->sq_head - ctx->sq_tail >= (int) ARRAY_SIZE(ctx->queue)) {
        (void) pthread_cond_wait(&ctx->sq_empty, &ctx->mutex);
    }

    if (ctx->sq_head - ctx->sq_tail < (int) ARRAY_SIZE(ctx->queue)) {
        // Copy socket to the queue and increment head
        ctx->queue[ctx->sq_head % ARRAY_SIZE(ctx->queue)] = *sp;
        ctx->sq_head++;
        DEBUG_TRACE(("queued socket %d", sp->sock));
    }

    (void) pthread_cond_signal(&ctx->sq_full);
    (void) pthread_mutex_unlock(&ctx->mutex);
}

static int set_sock_timeout(SOCKET sock, int milliseconds)
{
#ifdef _WIN32
    DWORD t = milliseconds;
#else
    struct timeval t;
    t.tv_sec = milliseconds / 1000;
    t.tv_usec = (milliseconds * 1000) % 1000000;
#endif
    return setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (void *) &t, sizeof(t)) ||
           setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, (void *) &t, sizeof(t));
}

static void accept_new_connection(const struct socket *listener,
                                  struct mg_context *ctx)
{
    struct socket so;
    char src_addr[IP_ADDR_STR_LEN];
    socklen_t len = sizeof(so.rsa);
    int on = 1;

    if ((so.sock = accept(listener->sock, &so.rsa.sa, &len)) == INVALID_SOCKET) {
    } else if (!check_acl(ctx, ntohl(* (uint32_t *) &so.rsa.sin.sin_addr))) {
        sockaddr_to_string(src_addr, sizeof(src_addr), &so.rsa);
        mg_cry(fc(ctx), "%s: %s is not allowed to connect", __func__, src_addr);
        closesocket(so.sock);
    } else {
        // Put so socket structure into the queue
        DEBUG_TRACE(("Accepted socket %d", (int) so.sock));
        set_close_on_exec(so.sock, fc(ctx));
        so.is_ssl = listener->is_ssl;
        so.ssl_redir = listener->ssl_redir;
        if (getsockname(so.sock, &so.lsa.sa, &len) != 0) {
            mg_cry(fc(ctx), "%s: getsockname() failed: %s",
                   __func__, strerror(ERRNO));
        }
        // Set TCP keep-alive. This is needed because if HTTP-level keep-alive
        // is enabled, and client resets the connection, server won't get
        // TCP FIN or RST and will keep the connection open forever. With TCP
        // keep-alive, next keep-alive handshake will figure out that the client
        // is down and will close the server end.
        // Thanks to Igor Klopov who suggested the patch.
        if (setsockopt(so.sock, SOL_SOCKET, SO_KEEPALIVE, (void *) &on,
                       sizeof(on)) != 0) {
            mg_cry(fc(ctx),
                   "%s: setsockopt(SOL_SOCKET SO_KEEPALIVE) failed: %s",
                   __func__, strerror(ERRNO));
        }
        set_sock_timeout(so.sock, atoi(ctx->config[REQUEST_TIMEOUT]));
        produce_socket(ctx, &so);
    }
}

static void master_thread_run(void *thread_func_param)
{
    struct mg_context *ctx = (struct mg_context *) thread_func_param;
    struct pollfd *pfd;
    int i;
    int workerthreadcount;

    // Increase priority of the master thread
#if defined(_WIN32)
    SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_ABOVE_NORMAL);
#elif defined(USE_MASTER_THREAD_PRIORITY)
    int min_prio = sched_get_priority_min(SCHED_RR);
    int max_prio = sched_get_priority_max(SCHED_RR);
    if ((min_prio >=0) && (max_prio >= 0) &&
        ((USE_MASTER_THREAD_PRIORITY) <= max_prio) &&
        ((USE_MASTER_THREAD_PRIORITY) >= min_prio)
       ) {
        struct sched_param sched_param = {0};
        sched_param.sched_priority = (USE_MASTER_THREAD_PRIORITY);
        pthread_setschedparam(pthread_self(), SCHED_RR, &sched_param);
    }
#endif

    pfd = (struct pollfd *) calloc(ctx->num_listening_sockets, sizeof(pfd[0]));
    while (pfd != NULL && ctx->stop_flag == 0) {
        for (i = 0; i < ctx->num_listening_sockets; i++) {
            pfd[i].fd = ctx->listening_sockets[i].sock;
            pfd[i].events = POLLIN;
        }

        if (poll(pfd, ctx->num_listening_sockets, 200) > 0) {
            for (i = 0; i < ctx->num_listening_sockets; i++) {
                // NOTE(lsm): on QNX, poll() returns POLLRDNORM after the
                // successfull poll, and POLLIN is defined as (POLLRDNORM | POLLRDBAND)
                // Therefore, we're checking pfd[i].revents & POLLIN, not
                // pfd[i].revents == POLLIN.
                if (ctx->stop_flag == 0 && (pfd[i].revents & POLLIN)) {
                    accept_new_connection(&ctx->listening_sockets[i], ctx);
                }
            }
        }
    }
    free(pfd);
    DEBUG_TRACE(("stopping workers"));

    // Stop signal received: somebody called mg_stop. Quit.
    close_all_listening_sockets(ctx);

    // Wakeup workers that are waiting for connections to handle.
    pthread_cond_broadcast(&ctx->sq_full);

    // Wait until all threads finish
    (void) pthread_mutex_lock(&ctx->mutex);
    while (ctx->num_threads > 0) {
        (void) pthread_cond_wait(&ctx->cond, &ctx->mutex);
    }
    (void) pthread_mutex_unlock(&ctx->mutex);

    // Join all worker threads to avoid leaking threads.
    workerthreadcount = ctx->workerthreadcount;
    for (i = 0; i < workerthreadcount; i++) {
        mg_join_thread(ctx->workerthreadids[i]);
    }

    // All threads exited, no sync is needed. Destroy mutex and condvars
    (void) pthread_mutex_destroy(&ctx->mutex);
    (void) pthread_cond_destroy(&ctx->cond);
    (void) pthread_cond_destroy(&ctx->sq_empty);
    (void) pthread_cond_destroy(&ctx->sq_full);

#if !defined(NO_SSL)
    uninitialize_ssl(ctx);
#endif
    DEBUG_TRACE(("exiting"));

    // Signal mg_stop() that we're done.
    // WARNING: This must be the very last thing this
    // thread does, as ctx becomes invalid after this line.
    ctx->stop_flag = 2;
}

/* Threads have different return types on Windows and Unix. */

#ifdef _WIN32
static unsigned __stdcall master_thread(void *thread_func_param)
{
    master_thread_run(thread_func_param);
    return 0;
}
#else
static void *master_thread(void *thread_func_param)
{
    master_thread_run(thread_func_param);
    return NULL;
}
#endif /* _WIN32 */

static void free_context(struct mg_context *ctx)
{
    int i;
    struct mg_request_handler_info *tmp_rh;

    if (ctx == NULL)
        return;

    // Deallocate config parameters
    for (i = 0; i < NUM_OPTIONS; i++) {
        if (ctx->config[i] != NULL)
#ifdef WIN32
#pragma warning(suppress: 6001)
#endif
            free(ctx->config[i]);
    }

    // Deallocate request handlers
    while (ctx->request_handlers) {
        tmp_rh = ctx->request_handlers;
        ctx->request_handlers = tmp_rh->next;
        free(tmp_rh->uri);
        free(tmp_rh);
    }

#ifndef NO_SSL
    // Deallocate SSL context
    if (ctx->ssl_ctx != NULL) {
        SSL_CTX_free(ctx->ssl_ctx);
    }
    if (ssl_mutexes != NULL) {
        free(ssl_mutexes);
        ssl_mutexes = NULL;
    }
#endif // !NO_SSL

    // Deallocate worker thread ID array
    if (ctx->workerthreadids != NULL) {
        free(ctx->workerthreadids);
    }

    // Deallocate context itself
    free(ctx);
}

void mg_stop(struct mg_context *ctx)
{
    ctx->stop_flag = 1;

    // Wait until mg_fini() stops
    while (ctx->stop_flag != 2) {
        (void) mg_sleep(10);
    }
    mg_join_thread(ctx->masterthreadid);
    free_context(ctx);

#if defined(_WIN32) && !defined(__SYMBIAN32__)
    (void) WSACleanup();
#endif // _WIN32
}

struct mg_context *mg_start(const struct mg_callbacks *callbacks,
                            void *user_data,
                            const char **options)
{
    struct mg_context *ctx;
    const char *name, *value, *default_value;
    int i;
    int workerthreadcount;

#if defined(_WIN32) && !defined(__SYMBIAN32__)
    WSADATA data;
    WSAStartup(MAKEWORD(2,2), &data);
#pragma warning(suppress: 28125)
    InitializeCriticalSection(&global_log_file_lock);
#endif // _WIN32

    // Allocate context and initialize reasonable general case defaults.
    // TODO(lsm): do proper error handling here.
    if ((ctx = (struct mg_context *) calloc(1, sizeof(*ctx))) == NULL) {
        return NULL;
    }
    ctx->callbacks = *callbacks;
    ctx->user_data = user_data;
    ctx->request_handlers = 0;

    while (options && (name = *options++) != NULL) {
        if ((i = get_option_index(name)) == -1) {
            mg_cry(fc(ctx), "Invalid option: %s", name);
            free_context(ctx);
            return NULL;
        } else if ((value = *options++) == NULL) {
            mg_cry(fc(ctx), "%s: option value cannot be NULL", name);
            free_context(ctx);
            return NULL;
        }
        if (ctx->config[i] != NULL) {
            mg_cry(fc(ctx), "warning: %s: duplicate option", name);
            free(ctx->config[i]);
        }
        ctx->config[i] = mg_strdup(value);
        DEBUG_TRACE(("[%s] -> [%s]", name, value));
    }

    // Set default value if needed
    for (i = 0; config_options[i * 2] != NULL; i++) {
        default_value = config_options[i * 2 + 1];
        if (ctx->config[i] == NULL && default_value != NULL) {
            ctx->config[i] = mg_strdup(default_value);
        }
    }

    // NOTE(lsm): order is important here. SSL certificates must
    // be initialized before listening ports. UID must be set last.
    if (!set_gpass_option(ctx) ||
#if !defined(NO_SSL)
        !set_ssl_option(ctx) ||
#endif
        !set_ports_option(ctx) ||
#if !defined(_WIN32)
        !set_uid_option(ctx) ||
#endif
        !set_acl_option(ctx)) {
        free_context(ctx);
        return NULL;
    }

#if !defined(_WIN32) && !defined(__SYMBIAN32__)
    // Ignore SIGPIPE signal, so if browser cancels the request, it
    // won't kill the whole process.
    (void) signal(SIGPIPE, SIG_IGN);
#endif // !_WIN32

    (void) pthread_mutex_init(&ctx->mutex, NULL);
    (void) pthread_cond_init(&ctx->cond, NULL);
    (void) pthread_cond_init(&ctx->sq_empty, NULL);
    (void) pthread_cond_init(&ctx->sq_full, NULL);

    workerthreadcount = atoi(ctx->config[NUM_THREADS]);

    if (workerthreadcount > MAX_WORKER_THREADS) {
        mg_cry(fc(ctx), "Too many worker threads");
        free_context(ctx);
        return NULL;
    }

    if (workerthreadcount > 0) {
        ctx->workerthreadcount = workerthreadcount;
        ctx->workerthreadids = calloc(workerthreadcount, sizeof(pthread_t));
        if (ctx->workerthreadids == NULL) {
            mg_cry(fc(ctx), "Not enough memory for worker thread ID array");
            free_context(ctx);
            return NULL;
        }
    }

    // Start master (listening) thread
    mg_start_thread_with_id(master_thread, ctx, &ctx->masterthreadid);

    // Start worker threads
    for (i = 0; i < workerthreadcount; i++) {
        (void) pthread_mutex_lock(&ctx->mutex);
        ctx->num_threads++;
        (void) pthread_mutex_unlock(&ctx->mutex);
        if (mg_start_thread_with_id(worker_thread, ctx,
                                    &ctx->workerthreadids[i]) != 0) {
            (void) pthread_mutex_lock(&ctx->mutex);
            ctx->num_threads--;
            (void) pthread_mutex_unlock(&ctx->mutex);
            mg_cry(fc(ctx), "Cannot start worker thread: %ld", (long) ERRNO);
        }
    }

    return ctx;
}