civetweb/src/mod_lua.inl

#include "civetweb_lua.h"
#include "civetweb_private_lua.h"

#ifdef _WIN32
static void *
mmap(void *addr, int64_t len, int prot, int flags, int fd, int offset)
{
	/* TODO (low): This is an incomplete implementation of mmap for windows.
	 * Currently it is sufficient, but there are a lot of unused parameters.
	 * Better use a function "mg_map" which only has the required parameters,
	 * and implement it using mmap in Linux and CreateFileMapping in Windows.
	 * Noone should expect a full mmap for Windows here.
	 */
	HANDLE fh = (HANDLE)_get_osfhandle(fd);
	HANDLE mh = CreateFileMapping(fh, 0, PAGE_READONLY, 0, 0, 0);
	void *p = MapViewOfFile(mh, FILE_MAP_READ, 0, 0, (size_t)len);
	CloseHandle(mh);

	/* unused parameters */
	(void)addr;
	(void)prot;
	(void)flags;
	(void)offset;

	return p;
}

static void
munmap(void *addr, int64_t length)
{
	/* unused parameters */
	(void)length;

	UnmapViewOfFile(addr);
}

#define MAP_FAILED (NULL)
#define MAP_PRIVATE (0)
#define PROT_READ (0)
#else
#include <sys/mman.h>
#endif

static const char *LUASOCKET = "luasocket";
static const char lua_regkey_ctx = 1;
static const char lua_regkey_connlist = 2;

/* Forward declarations */
static void handle_request(struct mg_connection *);
static int handle_lsp_request(struct mg_connection *,
                              const char *,
                              struct mg_file *,
                              struct lua_State *);

static void
reg_lstring(struct lua_State *L,
            const char *name,
            const void *buffer,
            size_t buflen)
{
	if (name != NULL && buffer != NULL) {
		lua_pushstring(L, name);
		lua_pushlstring(L, (const char *)buffer, buflen);
		lua_rawset(L, -3);
	}
}

#define reg_string(L, name, val)                                               \
	reg_lstring(L, name, val, val ? strlen(val) : 0)

static void
reg_int(struct lua_State *L, const char *name, int val)
{
	if (name != NULL) {
		lua_pushstring(L, name);
		lua_pushinteger(L, val);
		lua_rawset(L, -3);
	}
}

static void
reg_boolean(struct lua_State *L, const char *name, int val)
{
	if (name != NULL) {
		lua_pushstring(L, name);
		lua_pushboolean(L, val != 0);
		lua_rawset(L, -3);
	}
}

static void
reg_conn_function(struct lua_State *L,
                  const char *name,
                  lua_CFunction func,
                  struct mg_connection *conn)
{
	if (name != NULL && func != NULL && conn != NULL) {
		lua_pushstring(L, name);
		lua_pushlightuserdata(L, conn);
		lua_pushcclosure(L, func, 1);
		lua_rawset(L, -3);
	}
}

static void
reg_function(struct lua_State *L, const char *name, lua_CFunction func)
{
	if (name != NULL && func != NULL) {
		lua_pushstring(L, name);
		lua_pushcclosure(L, func, 0);
		lua_rawset(L, -3);
	}
}

static void
lua_cry(struct mg_connection *conn,
        int err,
        lua_State *L,
        const char *lua_title,
        const char *lua_operation)
{
	switch (err) {
	case LUA_OK:
	case LUA_YIELD:
		break;
	case LUA_ERRRUN:
		mg_cry(conn,
		       "%s: %s failed: runtime error: %s",
		       lua_title,
		       lua_operation,
		       lua_tostring(L, -1));
		break;
	case LUA_ERRSYNTAX:
		mg_cry(conn,
		       "%s: %s failed: syntax error: %s",
		       lua_title,
		       lua_operation,
		       lua_tostring(L, -1));
		break;
	case LUA_ERRMEM:
		mg_cry(conn, "%s: %s failed: out of memory", lua_title, lua_operation);
		break;
	case LUA_ERRGCMM:
		mg_cry(conn,
		       "%s: %s failed: error during garbage collection",
		       lua_title,
		       lua_operation);
		break;
	case LUA_ERRERR:
		mg_cry(conn,
		       "%s: %s failed: error in error handling: %s",
		       lua_title,
		       lua_operation,
		       lua_tostring(L, -1));
		break;
	default:
		mg_cry(conn, "%s: %s failed: error %i", lua_title, lua_operation, err);
		break;
	}
}

static int
lsp_sock_close(lua_State *L)
{
	int num_args = lua_gettop(L);
	size_t s;
	SOCKET *psock;

	if ((num_args == 1) && lua_istable(L, -1)) {
		lua_getfield(L, -1, "sock");
		psock = (SOCKET *)lua_tolstring(L, -1, &s);
		if (s != sizeof(SOCKET)) {
			return luaL_error(L, "invalid internal state in :close() call");
		}
		/* Do not closesocket(*psock); here, close it in __gc */
		(void)psock;
	} else {
		return luaL_error(L, "invalid :close() call");
	}
	return 0;
}

static int
lsp_sock_recv(lua_State *L)
{
	int num_args = lua_gettop(L);
	char buf[2000];
	int n;
	size_t s;
	SOCKET *psock;

	if ((num_args == 1) && lua_istable(L, -1)) {
		lua_getfield(L, -1, "sock");
		psock = (SOCKET *)lua_tolstring(L, -1, &s);
		if (s != sizeof(SOCKET)) {
			return luaL_error(L, "invalid internal state in :recv() call");
		}
		n = recv(*psock, buf, sizeof(buf), 0);
		if (n <= 0) {
			lua_pushnil(L);
		} else {
			lua_pushlstring(L, buf, n);
		}
	} else {
		return luaL_error(L, "invalid :recv() call");
	}
	return 1;
}

static int
lsp_sock_send(lua_State *L)
{
	int num_args = lua_gettop(L);
	const char *buf;
	size_t len, sent = 0;
	int n = 0;
	size_t s;
	SOCKET *psock;

	if ((num_args == 2) && lua_istable(L, -2) && lua_isstring(L, -1)) {
		buf = lua_tolstring(L, -1, &len);
		lua_getfield(L, -2, "sock");
		psock = (SOCKET *)lua_tolstring(L, -1, &s);
		if (s != sizeof(SOCKET)) {
			return luaL_error(L, "invalid internal state in :close() call");
		}

		while (sent < len) {
			if ((n = send(*psock, buf + sent, (int)(len - sent), 0)) <= 0) {
				break;
			}
			sent += n;
		}
		lua_pushnumber(L, n);
	} else {
		return luaL_error(L, "invalid :close() call");
	}
	return 1;
}

static int
lsp_sock_gc(lua_State *L)
{
	int num_args = lua_gettop(L);
	size_t s;
	SOCKET *psock;

	if ((num_args == 1) && lua_istable(L, -1)) {
		lua_getfield(L, -1, "sock");
		psock = (SOCKET *)lua_tolstring(L, -1, &s);
		if (s != sizeof(SOCKET)) {
			return luaL_error(
			    L,
			    "invalid internal state in __gc for object created by connect");
		}
		closesocket(*psock);
	} else {
		return luaL_error(L, "__gc for object created by connect failed");
	}
	return 0;
}

/* Methods and meta-methods supported by the object returned by connect.
 * For meta-methods, see http://lua-users.org/wiki/MetatableEvents */
static const struct luaL_Reg luasocket_methods[] = {{"close", lsp_sock_close},
                                                    {"send", lsp_sock_send},
                                                    {"recv", lsp_sock_recv},
                                                    {"__gc", lsp_sock_gc},
                                                    {NULL, NULL}};

static int
lsp_connect(lua_State *L)
{
	int num_args = lua_gettop(L);
	char ebuf[100];
	SOCKET sock;
	union usa sa;
	int ok;

	if ((num_args == 3) && lua_isstring(L, -3) && lua_isnumber(L, -2)
	    && lua_isnumber(L, -1)) {
		ok = connect_socket(NULL,
		                    lua_tostring(L, -3),
		                    (int)lua_tonumber(L, -2),
		                    (int)lua_tonumber(L, -1),
		                    ebuf,
		                    sizeof(ebuf),
		                    &sock,
		                    &sa);
		if (!ok) {
			return luaL_error(L, ebuf);
		} else {
			lua_newtable(L);
			reg_lstring(L, "sock", (const char *)&sock, sizeof(SOCKET));
			reg_string(L, "host", lua_tostring(L, -4));
			luaL_getmetatable(L, LUASOCKET);
			lua_setmetatable(L, -2);
		}
	} else {
		return luaL_error(
		    L, "connect(host,port,is_ssl): invalid parameter given.");
	}
	return 1;
}

static int
lsp_error(lua_State *L)
{
	lua_getglobal(L, "mg");
	lua_getfield(L, -1, "onerror");
	lua_pushvalue(L, -3);
	lua_pcall(L, 1, 0, 0);
	return 0;
}

/* Silently stop processing chunks. */
static void
lsp_abort(lua_State *L)
{
	int top = lua_gettop(L);
	lua_getglobal(L, "mg");
	lua_pushnil(L);
	lua_setfield(L, -2, "onerror");
	lua_settop(L, top);
	lua_pushstring(L, "aborting");
	lua_error(L);
}

struct lsp_var_reader_data {
	const char *begin;
	unsigned len;
	unsigned state;
};


static const char *
lsp_var_reader(lua_State *L, void *ud, size_t *sz)
{
	struct lsp_var_reader_data *reader = (struct lsp_var_reader_data *)ud;
	const char *ret;
	(void)(L); /* unused */

	switch (reader->state) {
	case 0:
		ret = "mg.write(";
		*sz = strlen(ret);
		break;
	case 1:
		ret = reader->begin;
		*sz = reader->len;
		break;
	case 2:
		ret = ")";
		*sz = strlen(ret);
		break;
	default:
		ret = 0;
		*sz = 0;
	}

	reader->state++;
	return ret;
}


static int
lsp(struct mg_connection *conn,
    const char *path,
    const char *p,
    int64_t len,
    lua_State *L)
{
	int i, j, pos = 0, lines = 1, lualines = 0, is_var, lua_ok;
	char chunkname[MG_BUF_LEN];
	struct lsp_var_reader_data data;

	for (i = 0; i < len; i++) {
		if (p[i] == '\n')
			lines++;
		if (((i + 1) < len) && (p[i] == '<') && (p[i + 1] == '?')) {

			/* <?= ?> means a variable is enclosed and its value should be
			 * printed */
			is_var = (((i + 2) < len) && (p[i + 2] == '='));

			if (is_var)
				j = i + 2;
			else
				j = i + 1;

			while (j < len) {
				if (p[j] == '\n')
					lualines++;
				if (((j + 1) < len) && (p[j] == '?') && (p[j + 1] == '>')) {
					mg_write(conn, p + pos, i - pos);

					mg_snprintf(conn,
					            NULL, /* name only used for debugging */
					            chunkname,
					            sizeof(chunkname),
					            "@%s+%i",
					            path,
					            lines);
					lua_pushlightuserdata(L, conn);
					lua_pushcclosure(L, lsp_error, 1);

					if (is_var) {
						data.begin = p + (i + 3);
						data.len = j - (i + 3);
						data.state = 0;
						lua_ok = mg_lua_load(
						    L, lsp_var_reader, &data, chunkname, NULL);
					} else {
						lua_ok = luaL_loadbuffer(L,
						                         p + (i + 2),
						                         j - (i + 2),
						                         chunkname);
					}

					if (lua_ok) {
						/* Syntax error or OOM. Error message is pushed on
						 * stack. */
						lua_pcall(L, 1, 0, 0);
					} else {
						/* Success loading chunk. Call it. */
						lua_pcall(L, 0, 0, 1);
					}

					pos = j + 2;
					i = pos - 1;
					break;
				}
				j++;
			}

			if (lualines > 0) {
				lines += lualines;
				lualines = 0;
			}
		}
	}

	if (i > pos) {
		mg_write(conn, p + pos, i - pos);
	}

	return 0;
}


/* mg.write: Send data to the client */
static int
lsp_write(lua_State *L)
{
	struct mg_connection *conn =
	    (struct mg_connection *)lua_touserdata(L, lua_upvalueindex(1));
	int num_args = lua_gettop(L);
	const char *str;
	size_t size;
	int i;
	int rv = 1;

	for (i = 1; i <= num_args; i++) {
		if (lua_isstring(L, i)) {
			str = lua_tolstring(L, i, &size);
			if (mg_write(conn, str, size) != (int)size) {
				rv = 0;
			}
		}
	}
	lua_pushboolean(L, rv);

	return 1;
}


/* mg.read: Read data from the client (e.g., from a POST request) */
static int
lsp_read(lua_State *L)
{
	struct mg_connection *conn =
	    (struct mg_connection *)lua_touserdata(L, lua_upvalueindex(1));
	char buf[1024];
	int len = mg_read(conn, buf, sizeof(buf));

	if (len <= 0)
		return 0;
	lua_pushlstring(L, buf, len);

	return 1;
}


/* mg.keep_alive: Allow Lua pages to use the http keep-alive mechanism */
static int
lsp_keep_alive(lua_State *L)
{
	struct mg_connection *conn =
	    (struct mg_connection *)lua_touserdata(L, lua_upvalueindex(1));
	int num_args = lua_gettop(L);

	/* This function may be called with one parameter (boolean) to set the
	keep_alive state.
	Or without a parameter to just query the current keep_alive state. */
	if ((num_args == 1) && lua_isboolean(L, 1)) {
		conn->must_close = !lua_toboolean(L, 1);
	} else if (num_args != 0) {
		/* Syntax error */
		return luaL_error(L, "invalid keep_alive() call");
	}

	/* Return the current "keep_alive" state. This may be false, even it
	 * keep_alive(true) has been called. */
	lua_pushboolean(L, should_keep_alive(conn));
	return 1;
}


/* mg.include: Include another .lp file */
static int
lsp_include(lua_State *L)
{
	struct mg_connection *conn =
	    (struct mg_connection *)lua_touserdata(L, lua_upvalueindex(1));
	int num_args = lua_gettop(L);
	struct mg_file file = STRUCT_FILE_INITIALIZER;
	const char *filename = (num_args == 1) ? lua_tostring(L, 1) : NULL;

	if (filename) {
		if (handle_lsp_request(conn, filename, &file, L)) {
			/* handle_lsp_request returned an error code, meaning an error
			occured in
			the included page and mg.onerror returned non-zero. Stop processing.
			*/
			lsp_abort(L);
		}
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid include() call");
	}
	return 0;
}


/* mg.cry: Log an error. Default value for mg.onerror. */
static int
lsp_cry(lua_State *L)
{
	struct mg_connection *conn =
	    (struct mg_connection *)lua_touserdata(L, lua_upvalueindex(1));
	int num_args = lua_gettop(L);
	const char *text = (num_args == 1) ? lua_tostring(L, 1) : NULL;

	if (text) {
		mg_cry(conn, "%s", lua_tostring(L, -1));
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid cry() call");
	}
	return 0;
}


/* mg.redirect: Redirect the request (internally). */
static int
lsp_redirect(lua_State *L)
{
	struct mg_connection *conn =
	    (struct mg_connection *)lua_touserdata(L, lua_upvalueindex(1));
	int num_args = lua_gettop(L);
	const char *target = (num_args == 1) ? lua_tostring(L, 1) : NULL;

	if (target) {
		conn->request_info.local_uri = target;
		handle_request(conn);
		lsp_abort(L);
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid redirect() call");
	}
	return 0;
}


/* mg.send_file */
static int
lsp_send_file(lua_State *L)
{
	struct mg_connection *conn =
	    (struct mg_connection *)lua_touserdata(L, lua_upvalueindex(1));
	int num_args = lua_gettop(L);
	const char *filename = (num_args == 1) ? lua_tostring(L, 1) : NULL;

	if (filename) {
		mg_send_file(conn, filename);
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid send_file() call");
	}
	return 0;
}


/* mg.get_time */
static int
lsp_get_time(lua_State *L)
{
	int num_args = lua_gettop(L);
	int monotonic = (num_args > 0) ? lua_toboolean(L, 1) : 0;
	struct timespec ts;
	double d;

	clock_gettime(monotonic ? CLOCK_MONOTONIC : CLOCK_REALTIME, &ts);
	d = (double)ts.tv_sec + ((double)ts.tv_nsec * 1.0E-9);
	lua_pushnumber(L, d);
	return 1;
}


/* mg.get_var */
static int
lsp_get_var(lua_State *L)
{
	int num_args = lua_gettop(L);
	const char *data, *var_name;
	size_t data_len, occurrence;
	int ret;
	char dst[512];

	if (num_args >= 2 && num_args <= 3) {
		data = lua_tolstring(L, 1, &data_len);
		var_name = lua_tostring(L, 2);
		occurrence = (num_args > 2) ? (long)lua_tonumber(L, 3) : 0;

		ret =
		    mg_get_var2(data, data_len, var_name, dst, sizeof(dst), occurrence);
		if (ret >= 0) {
			/* Variable found: return value to Lua */
			lua_pushstring(L, dst);
		} else {
			/* Variable not found (TODO (mid): may be string too long) */
			lua_pushnil(L);
		}
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid get_var() call");
	}
	return 1;
}


/* mg.get_mime_type */
static int
lsp_get_mime_type(lua_State *L)
{
	int num_args = lua_gettop(L);
	struct vec mime_type = {0, 0};
	struct mg_context *ctx;
	const char *text;

	lua_pushlightuserdata(L, (void *)&lua_regkey_ctx);
	lua_gettable(L, LUA_REGISTRYINDEX);
	ctx = (struct mg_context *)lua_touserdata(L, -1);

	if (num_args == 1) {
		text = lua_tostring(L, 1);
		if (text) {
			if (ctx) {
				get_mime_type(ctx, text, &mime_type);
				lua_pushlstring(L, mime_type.ptr, mime_type.len);
			} else {
				text = mg_get_builtin_mime_type(text);
				lua_pushstring(L, text);
			}
		} else {
			/* Syntax error */
			return luaL_error(L, "invalid argument for get_mime_type() call");
		}
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid get_mime_type() call");
	}
	return 1;
}


/* mg.get_cookie */
static int
lsp_get_cookie(lua_State *L)
{
	int num_args = lua_gettop(L);
	const char *cookie;
	const char *var_name;
	int ret;
	char dst[512];

	if (num_args == 2) {
		cookie = lua_tostring(L, 1);
		var_name = lua_tostring(L, 2);
		if (cookie != NULL && var_name != NULL) {
			ret = mg_get_cookie(cookie, var_name, dst, sizeof(dst));
		} else {
			ret = -1;
		}

		if (ret >= 0) {
			lua_pushlstring(L, dst, ret);
		} else {
			lua_pushnil(L);
		}
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid get_cookie() call");
	}
	return 1;
}


/* mg.md5 */
static int
lsp_md5(lua_State *L)
{
	int num_args = lua_gettop(L);
	const char *text;
	md5_byte_t hash[16];
	md5_state_t ctx;
	size_t text_len;
	char buf[40];

	if (num_args == 1) {
		text = lua_tolstring(L, 1, &text_len);
		if (text) {
			md5_init(&ctx);
			md5_append(&ctx, (const md5_byte_t *)text, text_len);
			md5_finish(&ctx, hash);
			bin2str(buf, hash, sizeof(hash));
			lua_pushstring(L, buf);
		} else {
			lua_pushnil(L);
		}
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid md5() call");
	}
	return 1;
}


/* mg.url_encode */
static int
lsp_url_encode(lua_State *L)
{
	int num_args = lua_gettop(L);
	const char *text;
	size_t text_len;
	char dst[512 * 3];

	if (num_args == 1) {
		text = lua_tolstring(L, 1, &text_len);
		if (text) {
			mg_url_encode(text, dst, sizeof(dst));
			lua_pushstring(L, dst);
		} else {
			lua_pushnil(L);
		}
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid url_encode() call");
	}
	return 1;
}


/* mg.url_decode */
static int
lsp_url_decode(lua_State *L)
{
	int num_args = lua_gettop(L);
	const char *text;
	size_t text_len;
	int is_form;
	char dst[512];

	if (num_args == 1 || (num_args == 2 && lua_isboolean(L, 2))) {
		text = lua_tolstring(L, 1, &text_len);
		is_form = (num_args == 2) ? lua_isboolean(L, 2) : 0;
		if (text) {
			mg_url_decode(text, text_len, dst, (int)sizeof(dst), is_form);
			lua_pushstring(L, dst);
		} else {
			lua_pushnil(L);
		}
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid url_decode() call");
	}
	return 1;
}


/* mg.base64_encode */
static int
lsp_base64_encode(lua_State *L)
{
	int num_args = lua_gettop(L);
	const char *text;
	size_t text_len;
	char *dst;

	if (num_args == 1) {
		text = lua_tolstring(L, 1, &text_len);
		if (text) {
			dst = (char *)mg_malloc(text_len * 8 / 6 + 4);
			if (dst) {
				base64_encode((const unsigned char *)text, (int)text_len, dst);
				lua_pushstring(L, dst);
				mg_free(dst);
			} else {
				return luaL_error(L, "out of memory in base64_encode() call");
			}
		} else {
			lua_pushnil(L);
		}
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid base64_encode() call");
	}
	return 1;
}


/* mg.base64_encode */
static int
lsp_base64_decode(lua_State *L)
{
	int num_args = lua_gettop(L);
	const char *text;
	size_t text_len, dst_len;
	int ret;
	char *dst;

	if (num_args == 1) {
		text = lua_tolstring(L, 1, &text_len);
		if (text) {
			dst = (char *)mg_malloc(text_len);
			if (dst) {
				ret = base64_decode((const unsigned char *)text,
				                    (int)text_len,
				                    dst,
				                    &dst_len);
				if (ret != -1) {
					mg_free(dst);
					return luaL_error(
					    L, "illegal character in lsp_base64_decode() call");
				} else {
					lua_pushlstring(L, dst, dst_len);
					mg_free(dst);
				}
			} else {
				return luaL_error(L,
				                  "out of memory in lsp_base64_decode() call");
			}
		} else {
			lua_pushnil(L);
		}
	} else {
		/* Syntax error */
		return luaL_error(L, "invalid lsp_base64_decode() call");
	}
	return 1;
}


/* mg.get_response_code_text */
static int
lsp_get_response_code_text(lua_State *L)
{
	int num_args = lua_gettop(L);
	int type1;
	double code;
	const char *text;

	if (num_args == 1) {
		type1 = lua_type(L, 1);
		if (type1 == LUA_TNUMBER) {
			/* If the first argument is a number,
			   convert it to the corresponding text. */
			code = lua_tonumber(L, 1);
			text = mg_get_response_code_text(NULL, (int)code);
			if (text)
				lua_pushstring(L, text);
			return text ? 1 : 0;
		}
	}

	/* Syntax error */
	return luaL_error(L, "invalid get_response_code_text() call");
}


/* mg.random - might be better than math.random on some systems */
static int
lsp_random(lua_State *L)
{
	int num_args = lua_gettop(L);
	if (num_args == 0) {
		/* The civetweb internal random number generator will generate
		         * a 64 bit random number. */
		uint64_t r = get_random();
		/* Lua "number" is a IEEE 754 double precission float:
 * https://en.wikipedia.org/wiki/Double-precision_floating-point_format
		 * Thus, mask with 2^53-1 to get an integer with the maximum
 * precission available. */
		r &= ((((uint64_t)1) << 53) - 1);
		lua_pushnumber(L, (double)r);
		return 1;
	}

	/* Syntax error */
	return luaL_error(L, "invalid random() call");
}


union {
	void *p;
	void (*f)(unsigned char uuid[16]);
} pf_uuid_generate;


/* mg.uuid */
static int
lsp_uuid(lua_State *L)
{
	union {
		unsigned char uuid_array[16];
		struct uuid_struct_type {
			uint32_t data1;
			uint16_t data2;
			uint16_t data3;
			uint8_t data4[8];
		} uuid_struct;
	} uuid;

	char uuid_str[40];
	int num_args = lua_gettop(L);

	memset(&uuid, 0, sizeof(uuid));
	memset(uuid_str, 0, sizeof(uuid_str));

	if (num_args == 0) {

		pf_uuid_generate.f(uuid.uuid_array);

		sprintf(uuid_str,
		        "{%08lX-%04X-%04X-%02X%02X-"
		        "%02X%02X%02X%02X%02X%02X}",
		        (unsigned long)uuid.uuid_struct.data1,
		        (unsigned)uuid.uuid_struct.data2,
		        (unsigned)uuid.uuid_struct.data3,
		        (unsigned)uuid.uuid_struct.data4[0],
		        (unsigned)uuid.uuid_struct.data4[1],
		        (unsigned)uuid.uuid_struct.data4[2],
		        (unsigned)uuid.uuid_struct.data4[3],
		        (unsigned)uuid.uuid_struct.data4[4],
		        (unsigned)uuid.uuid_struct.data4[5],
		        (unsigned)uuid.uuid_struct.data4[6],
		        (unsigned)uuid.uuid_struct.data4[7]);

		lua_pushstring(L, uuid_str);
		return 1;
	}

	/* Syntax error */
	return luaL_error(L, "invalid random() call");
}


#ifdef USE_WEBSOCKET
struct lua_websock_data {
	lua_State *state;
	char *script;
	unsigned references;
	struct mg_connection *conn[MAX_WORKER_THREADS];
	pthread_mutex_t ws_mutex;
};
#endif


/* mg.write for websockets */
static int
lwebsock_write(lua_State *L)
{
#ifdef USE_WEBSOCKET
	int num_args = lua_gettop(L);
	struct lua_websock_data *ws;
	const char *str;
	size_t size;
	int opcode = -1;
	unsigned i;
	struct mg_connection *client = NULL;

	lua_pushlightuserdata(L, (void *)&lua_regkey_connlist);
	lua_gettable(L, LUA_REGISTRYINDEX);
	ws = (struct lua_websock_data *)lua_touserdata(L, -1);

	(void)pthread_mutex_lock(&(ws->ws_mutex));

	if (num_args == 1) {
		/* just one text: send it to all client */
		if (lua_isstring(L, 1)) {
			opcode = WEBSOCKET_OPCODE_TEXT;
		}
	} else if (num_args == 2) {
		if (lua_isnumber(L, 1)) {
			/* opcode number and message text */
			opcode = (int)lua_tointeger(L, 1);
		} else if (lua_isstring(L, 1)) {
			/* opcode string and message text */
			str = lua_tostring(L, 1);
			if (!mg_strncasecmp(str, "text", 4))
				opcode = WEBSOCKET_OPCODE_TEXT;
			else if (!mg_strncasecmp(str, "bin", 3))
				opcode = WEBSOCKET_OPCODE_BINARY;
			else if (!mg_strncasecmp(str, "close", 5))
				opcode = WEBSOCKET_OPCODE_CONNECTION_CLOSE;
			else if (!mg_strncasecmp(str, "ping", 4))
				opcode = WEBSOCKET_OPCODE_PING;
			else if (!mg_strncasecmp(str, "pong", 4))
				opcode = WEBSOCKET_OPCODE_PONG;
			else if (!mg_strncasecmp(str, "cont", 4))
				opcode = WEBSOCKET_OPCODE_CONTINUATION;
		} else if (lua_isuserdata(L, 1)) {
			/* client id and message text */
			client = (struct mg_connection *)lua_touserdata(L, 1);
			opcode = WEBSOCKET_OPCODE_TEXT;
		}
	} else if (num_args == 3) {
		if (lua_isuserdata(L, 1)) {
			client = (struct mg_connection *)lua_touserdata(L, 1);
			if (lua_isnumber(L, 2)) {
				/* client id, opcode number and message text */
				opcode = (int)lua_tointeger(L, 2);
			} else if (lua_isstring(L, 2)) {
				/* client id, opcode string and message text */
				str = lua_tostring(L, 2);
				if (!mg_strncasecmp(str, "text", 4))
					opcode = WEBSOCKET_OPCODE_TEXT;
				else if (!mg_strncasecmp(str, "bin", 3))
					opcode = WEBSOCKET_OPCODE_BINARY;
				else if (!mg_strncasecmp(str, "close", 5))
					opcode = WEBSOCKET_OPCODE_CONNECTION_CLOSE;
				else if (!mg_strncasecmp(str, "ping", 4))
					opcode = WEBSOCKET_OPCODE_PING;
				else if (!mg_strncasecmp(str, "pong", 4))
					opcode = WEBSOCKET_OPCODE_PONG;
				else if (!mg_strncasecmp(str, "cont", 4))
					opcode = WEBSOCKET_OPCODE_CONTINUATION;
			}
		}
	}

	if (opcode >= 0 && opcode < 16 && lua_isstring(L, num_args)) {
		str = lua_tolstring(L, num_args, &size);
		if (client) {
			for (i = 0; i < ws->references; i++) {
				if (client == ws->conn[i]) {
					mg_websocket_write(ws->conn[i], opcode, str, size);
				}
			}
		} else {
			for (i = 0; i < ws->references; i++) {
				mg_websocket_write(ws->conn[i], opcode, str, size);
			}
		}
	} else {
		(void)pthread_mutex_unlock(&(ws->ws_mutex));
		return luaL_error(L, "invalid websocket write() call");
	}

	(void)pthread_mutex_unlock(&(ws->ws_mutex));

#else
	(void)(L);           /* unused */
#endif
	return 0;
}


struct laction_arg {
	lua_State *state;
	const char *script;
	pthread_mutex_t *pmutex;
	char txt[1];
};


static int
lua_action(struct laction_arg *arg)
{
	int err, ok;
	struct mg_context *ctx;

	(void)pthread_mutex_lock(arg->pmutex);

	lua_pushlightuserdata(arg->state, (void *)&lua_regkey_ctx);
	lua_gettable(arg->state, LUA_REGISTRYINDEX);
	ctx = (struct mg_context *)lua_touserdata(arg->state, -1);

	err = luaL_loadstring(arg->state, arg->txt);
	if (err != 0) {
		lua_cry(fc(ctx), err, arg->state, arg->script, "timer");
		(void)pthread_mutex_unlock(arg->pmutex);
		mg_free(arg);
		return 0;
	}
	err = lua_pcall(arg->state, 0, 1, 0);
	if (err != 0) {
		lua_cry(fc(ctx), err, arg->state, arg->script, "timer");
		(void)pthread_mutex_unlock(arg->pmutex);
		mg_free(arg);
		return 0;
	}

	ok = lua_type(arg->state, -1);
	if (lua_isboolean(arg->state, -1)) {
		ok = lua_toboolean(arg->state, -1);
	} else {
		ok = 0;
	}
	lua_pop(arg->state, 1);

	(void)pthread_mutex_unlock(arg->pmutex);

	if (!ok) {
		mg_free(arg);
	}
	return ok;
}


static int
lua_action_free(struct laction_arg *arg)
{
	if (lua_action(arg)) {
		mg_free(arg);
	}
	return 0;
}


static int
lwebsocket_set_timer(lua_State *L, int is_periodic)
{
#if defined(USE_TIMERS) && defined(USE_WEBSOCKET)
	int num_args = lua_gettop(L);
	struct lua_websock_data *ws;
	int type1, type2, ok = 0;
	double timediff;
	struct mg_context *ctx;
	struct laction_arg *arg;
	const char *txt;
	size_t txt_len;

	lua_pushlightuserdata(L, (void *)&lua_regkey_ctx);
	lua_gettable(L, LUA_REGISTRYINDEX);
	ctx = (struct mg_context *)lua_touserdata(L, -1);

	lua_pushlightuserdata(L, (void *)&lua_regkey_connlist);
	lua_gettable(L, LUA_REGISTRYINDEX);
	ws = (struct lua_websock_data *)lua_touserdata(L, -1);

	if (num_args < 2) {
		return luaL_error(L,
		                  "not enough arguments for set_timer/interval() call");
	}

	type1 = lua_type(L, 1);
	type2 = lua_type(L, 2);

	if (type1 == LUA_TSTRING && type2 == LUA_TNUMBER && num_args == 2) {
		timediff = (double)lua_tonumber(L, 2);
		txt = lua_tostring(L, 1);
		txt_len = strlen(txt);
		arg = (struct laction_arg *)mg_malloc(sizeof(struct laction_arg)
		                                      + txt_len + 10);
		arg->state = L;
		arg->script = ws->script;
		arg->pmutex = &(ws->ws_mutex);
		memcpy(arg->txt, "return(", 7);
		memcpy(arg->txt + 7, txt, txt_len);
		arg->txt[txt_len + 7] = ')';
		arg->txt[txt_len + 8] = 0;
		ok =
		    (0
		     == timer_add(ctx,
		                  timediff,
		                  is_periodic,
		                  1,
		                  (taction)(is_periodic ? lua_action : lua_action_free),
		                  (void *)arg));
	} else if (type1 == LUA_TFUNCTION && type2 == LUA_TNUMBER) {
		/* TODO (mid): not implemented yet */
		return luaL_error(L, "invalid arguments for set_timer/interval() call");
	} else {
		return luaL_error(L, "invalid arguments for set_timer/interval() call");
	}

	lua_pushboolean(L, ok);
	return 1;

#else
	(void)(L);           /* unused */
	(void)(is_periodic); /* unused */
	return 0;
#endif
}


/* mg.set_timeout for websockets */
static int
lwebsocket_set_timeout(lua_State *L)
{
	return lwebsocket_set_timer(L, 0);
}


/* mg.set_interval for websockets */
static int
lwebsocket_set_interval(lua_State *L)
{
	return lwebsocket_set_timer(L, 1);
}

enum {
	LUA_ENV_TYPE_LUA_SERVER_PAGE = 0,
	LUA_ENV_TYPE_PLAIN_LUA_PAGE = 1,
	LUA_ENV_TYPE_LUA_WEBSOCKET = 2,
};


static void
prepare_lua_request_info(struct mg_connection *conn, lua_State *L)
{
	const char *s;
	int i;

	/* Export mg.request_info */
	lua_pushstring(L, "request_info");
	lua_newtable(L);
	reg_string(L, "request_method", conn->request_info.request_method);
	reg_string(L, "request_uri", conn->request_info.request_uri);
	reg_string(L, "uri", conn->request_info.local_uri);
	reg_string(L, "http_version", conn->request_info.http_version);
	reg_string(L, "query_string", conn->request_info.query_string);
#if defined(MG_LEGACY_INTERFACE)
	reg_int(L, "remote_ip", conn->request_info.remote_ip); /* remote_ip is
	                                                          deprecated, use
	                                                          remote_addr
	                                                          instead */
#endif
	reg_string(L, "remote_addr", conn->request_info.remote_addr);
	/* TODO (high): ip version */
	reg_int(L, "remote_port", conn->request_info.remote_port);
	reg_int(L, "num_headers", conn->request_info.num_headers);
	reg_int(L, "server_port", ntohs(conn->client.lsa.sin.sin_port));

	if (conn->path_info != NULL) {
		reg_string(L, "path_info", conn->path_info);
	}

	if (conn->request_info.content_length >= 0) {
		/* reg_int64: content_length */
		lua_pushstring(L, "content_length");
		lua_pushnumber(
		    L,
		    (lua_Number)conn->request_info
		        .content_length); /* lua_Number may be used as 52 bit integer */
		lua_rawset(L, -3);
	}
	if ((s = mg_get_header(conn, "Content-Type")) != NULL) {
		reg_string(L, "content_type", s);
	}

	if (conn->request_info.remote_user != NULL) {
		reg_string(L, "remote_user", conn->request_info.remote_user);
		reg_string(L, "auth_type", "Digest");
	}

	reg_boolean(L, "https", conn->ssl != NULL);

	if (conn->status_code > 0) {
		/* Lua error handler should show the status code */
		reg_int(L, "status", conn->status_code);
	}

	lua_pushstring(L, "http_headers");
	lua_newtable(L);
	for (i = 0; i < conn->request_info.num_headers; i++) {
		reg_string(L,
		           conn->request_info.http_headers[i].name,
		           conn->request_info.http_headers[i].value);
	}
	lua_rawset(L, -3);

	lua_rawset(L, -3);
}


void
civetweb_open_lua_libs(lua_State *L)
{
	{
		extern void luaL_openlibs(lua_State *);
		luaL_openlibs(L);
	}

#ifdef USE_LUA_SQLITE3
	{
		extern int luaopen_lsqlite3(lua_State *);
		luaopen_lsqlite3(L);
	}
#endif
#ifdef USE_LUA_LUAXML
	{
		extern int luaopen_LuaXML_lib(lua_State *);
		luaopen_LuaXML_lib(L);
	}
#endif
#ifdef USE_LUA_FILE_SYSTEM
	{
		extern int luaopen_lfs(lua_State *);
		luaopen_lfs(L);
	}
#endif
#ifdef USE_LUA_BINARY
	{
		/* TODO (low): Test if this could be used as a replacement for bit32.
		 * Check again with Lua 5.3 later. */
		extern int luaopen_binary(lua_State *);

		luaL_requiref(L, "binary", luaopen_binary, 1);
		lua_pop(L, 1);
	}
#endif
}


static void
prepare_lua_environment(struct mg_context *ctx,
                        struct mg_connection *conn,
                        struct lua_websock_data *ws_conn_list,
                        lua_State *L,
                        const char *script_name,
                        int lua_env_type)
{
	civetweb_open_lua_libs(L);

#if LUA_VERSION_NUM == 502
	/* Keep the "connect" method for compatibility,
	 * but do not backport it to Lua 5.1.
	 * TODO: Redesign the interface.
	 */
	luaL_newmetatable(L, LUASOCKET);
	lua_pushliteral(L, "__index");
	luaL_newlib(L, luasocket_methods);
	lua_rawset(L, -3);
	lua_pop(L, 1);
	lua_register(L, "connect", lsp_connect);
#endif

	/* Store context in the registry */
	if (ctx != NULL) {
		lua_pushlightuserdata(L, (void *)&lua_regkey_ctx);
		lua_pushlightuserdata(L, (void *)ctx);
		lua_settable(L, LUA_REGISTRYINDEX);
	}
	if (ws_conn_list != NULL) {
		lua_pushlightuserdata(L, (void *)&lua_regkey_connlist);
		lua_pushlightuserdata(L, (void *)ws_conn_list);
		lua_settable(L, LUA_REGISTRYINDEX);
	}

	/* Register mg module */
	lua_newtable(L);

	switch (lua_env_type) {
	case LUA_ENV_TYPE_LUA_SERVER_PAGE:
		reg_string(L, "lua_type", "page");
		break;
	case LUA_ENV_TYPE_PLAIN_LUA_PAGE:
		reg_string(L, "lua_type", "script");
		break;
	case LUA_ENV_TYPE_LUA_WEBSOCKET:
		reg_string(L, "lua_type", "websocket");
		break;
	}

	if (lua_env_type == LUA_ENV_TYPE_LUA_SERVER_PAGE
	    || lua_env_type == LUA_ENV_TYPE_PLAIN_LUA_PAGE) {
		reg_conn_function(L, "cry", lsp_cry, conn);
		reg_conn_function(L, "read", lsp_read, conn);
		reg_conn_function(L, "write", lsp_write, conn);
		reg_conn_function(L, "keep_alive", lsp_keep_alive, conn);
		reg_conn_function(L, "send_file", lsp_send_file, conn);
	}

	if (lua_env_type == LUA_ENV_TYPE_LUA_SERVER_PAGE) {
		reg_conn_function(L, "include", lsp_include, conn);
		reg_conn_function(L, "redirect", lsp_redirect, conn);
	}

	if (lua_env_type == LUA_ENV_TYPE_LUA_WEBSOCKET) {
		reg_function(L, "write", lwebsock_write);
#ifdef USE_TIMERS
		reg_function(L, "set_timeout", lwebsocket_set_timeout);
		reg_function(L, "set_interval", lwebsocket_set_interval);
#endif
		/* reg_conn_function(L, "send_file", lsp_send_file, conn); */
	}

	reg_function(L, "time", lsp_get_time);
	reg_function(L, "get_var", lsp_get_var);
	reg_function(L, "get_mime_type", lsp_get_mime_type);
	reg_function(L, "get_cookie", lsp_get_cookie);
	reg_function(L, "md5", lsp_md5);
	reg_function(L, "url_encode", lsp_url_encode);
	reg_function(L, "url_decode", lsp_url_decode);
	reg_function(L, "base64_encode", lsp_base64_encode);
	reg_function(L, "base64_decode", lsp_base64_decode);
	reg_function(L, "get_response_code_text", lsp_get_response_code_text);
	reg_function(L, "random", lsp_random);
	if (pf_uuid_generate.f) {
		reg_function(L, "uuid", lsp_uuid);
	}

	reg_string(L, "version", CIVETWEB_VERSION);

	reg_string(L, "script_name", script_name);

	if (ctx != NULL) {
		reg_string(L, "document_root", ctx->config[DOCUMENT_ROOT]);
		reg_string(L, "auth_domain", ctx->config[AUTHENTICATION_DOMAIN]);
#if defined(USE_WEBSOCKET)
		if (ctx->config[WEBSOCKET_ROOT]) {
			reg_string(L, "websocket_root", ctx->config[WEBSOCKET_ROOT]);
		} else {
			reg_string(L, "websocket_root", ctx->config[DOCUMENT_ROOT]);
		}
#endif

		if (ctx->systemName != NULL) {
			reg_string(L, "system", ctx->systemName);
		}
	}

	/* Export connection specific info */
	if (conn != NULL) {
		prepare_lua_request_info(conn, L);
	}

	lua_setglobal(L, "mg");

	/* Register default mg.onerror function */
	IGNORE_UNUSED_RESULT(
	    luaL_dostring(L,
	                  "mg.onerror = function(e) mg.write('\\nLua error:\\n', "
	                  "debug.traceback(e, 1)) end"));

	if (ctx != NULL) {
		/* Preload */
		if (ctx->config[LUA_PRELOAD_FILE] != NULL) {
			IGNORE_UNUSED_RESULT(luaL_dofile(L, ctx->config[LUA_PRELOAD_FILE]));
		}

		if (ctx->callbacks.init_lua != NULL) {
			ctx->callbacks.init_lua(conn, L);
		}
	}
}


static int
lua_error_handler(lua_State *L)
{
	const char *error_msg = lua_isstring(L, -1) ? lua_tostring(L, -1) : "?\n";

	lua_getglobal(L, "mg");
	if (!lua_isnil(L, -1)) {
		lua_getfield(L, -1, "write"); /* call mg.write() */
		lua_pushstring(L, error_msg);
		lua_pushliteral(L, "\n");
		lua_call(L, 2, 0);
		IGNORE_UNUSED_RESULT(
		    luaL_dostring(L, "mg.write(debug.traceback(), '\\n')"));
	} else {
		printf("Lua error: [%s]\n", error_msg);
		IGNORE_UNUSED_RESULT(
		    luaL_dostring(L, "print(debug.traceback(), '\\n')"));
	}
	/* TODO(lsm, low): leave the stack balanced */

	return 0;
}


static void *
lua_allocator(void *ud, void *ptr, size_t osize, size_t nsize)
{
	(void)ud;
	(void)osize; /* not used */

	if (nsize == 0) {
		mg_free(ptr);
		return NULL;
	}
	return mg_realloc(ptr, nsize);
}


static void
mg_exec_lua_script(struct mg_connection *conn,
                   const char *path,
                   const void **exports)
{
	int i;
	lua_State *L;

	/* Assume the script does not support keep_alive. The script may change this
	 * by calling mg.keep_alive(true). */
	conn->must_close = 1;

	/* Execute a plain Lua script. */
	if (path != NULL && (L = lua_newstate(lua_allocator, NULL)) != NULL) {
		prepare_lua_environment(
		    conn->ctx, conn, NULL, L, path, LUA_ENV_TYPE_PLAIN_LUA_PAGE);
		lua_pushcclosure(L, &lua_error_handler, 0);

		if (exports != NULL) {
#if LUA_VERSION_NUM > 501
			lua_pushglobaltable(L);
			for (i = 0; exports[i] != NULL && exports[i + 1] != NULL; i += 2) {
				lua_CFunction func;
				lua_pushstring(L, (const char *)(exports[i]));
				*(const void **)(&func) = exports[i + 1];
				lua_pushcclosure(L, func, 0);
				lua_rawset(L, -3);
			}
#else
			for (i = 0; exports[i] != NULL && exports[i + 1] != NULL; i += 2) {
				lua_CFunction func;
				const char *name = (const char *)(exports[i]);
				*(const void **)(&func) = exports[i + 1];
				lua_register(L, name, func);
			}
#endif
		}

		if (luaL_loadfile(L, path) != 0) {
			lua_error_handler(L);
		}
		lua_pcall(L, 0, 0, -2);
		lua_close(L);
	}
}


static int
handle_lsp_request(struct mg_connection *conn,
                   const char *path,
                   struct mg_file *filep,
                   struct lua_State *ls)
{
	void *p = NULL;
	lua_State *L = NULL;
	int error = 1;
	struct mg_file filesize = STRUCT_FILE_INITIALIZER;

	/* Assume the script does not support keep_alive. The script may change this
	 * by calling mg.keep_alive(true). */
	conn->must_close = 1;

	/* We need both mg_stat to get file size, and mg_fopen to get fd */
	if (!mg_stat(conn, path, &filesize.stat)) {

		/* File not found */
		if (ls == NULL) {
			send_http_error(conn, 500, "Error: File %s not found", path);
		} else {
			luaL_error(ls, "File [%s] not found", path);
		}

		goto cleanup_handle_lsp_request;
	}

	if (!mg_fopen(conn, path, MG_FOPEN_MODE_READ, filep)) {

		/* File not found or not accessible */
		if (ls == NULL) {
			send_http_error(conn,
			                500,
			                "Error: Cannot open script file %s",
			                path);
		} else {
			luaL_error(ls, "Cannot  [%s] not found", path);
		}

		goto cleanup_handle_lsp_request;
	}

	/* TODO: Operations mg_fopen and mg_stat should do what their names
	 * indicate. They should not fill in different members of the same
	 * struct mg_file.
	 * See Github issue #225 */
	filep->stat.size = filesize.stat.size;

	if (filep->access.membuf == NULL
	    && (p = mmap(NULL,
	                 (size_t)filep->stat.size,
	                 PROT_READ,
	                 MAP_PRIVATE,
	                 fileno(filep->access.fp),
	                 0)) == MAP_FAILED) {

		/* mmap failed */
		if (ls == NULL) {
			send_http_error(
			    conn,
			    500,
			    "Error: Cannot open script\nFile %s can not be mapped",
			    path);
		} else {
			luaL_error(ls,
			           "mmap(%s, %zu, %d): %s",
			           path,
			           (size_t)filep->stat.size,
			           fileno(filep->access.fp),
			           strerror(errno));
		}

		goto cleanup_handle_lsp_request;
	}

	if (ls != NULL) {
		L = ls;
	} else {
		L = lua_newstate(lua_allocator, NULL);
		if (L == NULL) {
			send_http_error(
			    conn,
			    500,
			    "%s",
			    "Error: Cannot execute script\nlua_newstate failed");

			goto cleanup_handle_lsp_request;
		}
		prepare_lua_environment(
		    conn->ctx, conn, NULL, L, path, LUA_ENV_TYPE_LUA_SERVER_PAGE);
	}

	/* Lua state is ready to use */
	/* We're not sending HTTP headers here, Lua page must do it. */
	error =
	    lsp(conn,
	        path,
	        (filep->access.membuf == NULL) ? (const char *)p
	                                       : (const char *)filep->access.membuf,
	        filep->stat.size,
	        L);

cleanup_handle_lsp_request:

	if (L != NULL && ls == NULL)
		lua_close(L);
	if (p != NULL)
		munmap(p, filep->stat.size);
	(void)mg_fclose(&filep->access);

	return error;
}


#ifdef USE_WEBSOCKET
struct mg_shared_lua_websocket_list {
	struct lua_websock_data ws;
	struct mg_shared_lua_websocket_list *next;
};


static void *
lua_websocket_new(const char *script, struct mg_connection *conn)
{
	struct mg_shared_lua_websocket_list **shared_websock_list =
	    &(conn->ctx->shared_lua_websockets);
	struct lua_websock_data *ws;
	int err, ok = 0;

	assert(conn->lua_websocket_state == NULL);

	/* lock list (mg_context global) */
	mg_lock_context(conn->ctx);
	while (*shared_websock_list) {
		/* check if ws already in list */
		if (0 == strcmp(script, (*shared_websock_list)->ws.script)) {
			break;
		}
		shared_websock_list = &((*shared_websock_list)->next);
	}

	if (*shared_websock_list == NULL) {
		/* add ws to list */
		*shared_websock_list = (struct mg_shared_lua_websocket_list *)
		    mg_calloc(sizeof(struct mg_shared_lua_websocket_list), 1);
		if (*shared_websock_list == NULL) {
			mg_unlock_context(conn->ctx);
			mg_cry(conn, "Cannot create shared websocket struct, OOM");
			return NULL;
		}
		/* init ws list element */
		ws = &(*shared_websock_list)->ws;
		ws->script = mg_strdup(script); /* TODO (low): handle OOM */
		pthread_mutex_init(&(ws->ws_mutex), &pthread_mutex_attr);
		(void)pthread_mutex_lock(&(ws->ws_mutex));
		ws->state = lua_newstate(lua_allocator, NULL);
		ws->conn[0] = conn;
		ws->references = 1;
		prepare_lua_environment(
		    conn->ctx, NULL, ws, ws->state, script, LUA_ENV_TYPE_LUA_WEBSOCKET);
		err = luaL_loadfile(ws->state, script);
		if (err != 0) {
			lua_cry(conn, err, ws->state, script, "load");
		}
		err = lua_pcall(ws->state, 0, 0, 0);
		if (err != 0) {
			lua_cry(conn, err, ws->state, script, "init");
		}
	} else {
		/* inc ref count */
		ws = &(*shared_websock_list)->ws;
		(void)pthread_mutex_lock(&(ws->ws_mutex));
		(*shared_websock_list)->ws.conn[(ws->references)++] = conn;
	}
	mg_unlock_context(conn->ctx);

	/* call add */
	lua_getglobal(ws->state, "open");
	lua_newtable(ws->state);
	prepare_lua_request_info(conn, ws->state);
	lua_pushstring(ws->state, "client");
	lua_pushlightuserdata(ws->state, (void *)conn);
	lua_rawset(ws->state, -3);

	err = lua_pcall(ws->state, 1, 1, 0);
	if (err != 0) {
		lua_cry(conn, err, ws->state, script, "open handler");
	} else {
		if (lua_isboolean(ws->state, -1)) {
			ok = lua_toboolean(ws->state, -1);
		}
		lua_pop(ws->state, 1);
	}
	if (!ok) {
		/* Remove from ws connection list. */
		/* TODO (mid): Check if list entry and Lua state needs to be deleted
		 * (see websocket_close). */
		(*shared_websock_list)->ws.conn[--(ws->references)] = 0;
	}

	(void)pthread_mutex_unlock(&(ws->ws_mutex));

	return ok ? (void *)ws : NULL;
}


static int
lua_websocket_data(struct mg_connection *conn,
                   int bits,
                   char *data,
                   size_t data_len,
                   void *ws_arg)
{
	struct lua_websock_data *ws = (struct lua_websock_data *)(ws_arg);
	int err, ok = 0;

	assert(ws != NULL);
	assert(ws->state != NULL);

	(void)pthread_mutex_lock(&(ws->ws_mutex));

	lua_getglobal(ws->state, "data");
	lua_newtable(ws->state);
	lua_pushstring(ws->state, "client");
	lua_pushlightuserdata(ws->state, (void *)conn);
	lua_rawset(ws->state, -3);
	lua_pushstring(ws->state, "bits"); /* TODO: dont use "bits" but fields with
	                                      a meaning according to
	                                      http://tools.ietf.org/html/rfc6455,
	                                      section 5.2 */
	lua_pushnumber(ws->state, bits);
	lua_rawset(ws->state, -3);
	lua_pushstring(ws->state, "data");
	lua_pushlstring(ws->state, data, data_len);
	lua_rawset(ws->state, -3);

	err = lua_pcall(ws->state, 1, 1, 0);
	if (err != 0) {
		lua_cry(conn, err, ws->state, ws->script, "data handler");
	} else {
		if (lua_isboolean(ws->state, -1)) {
			ok = lua_toboolean(ws->state, -1);
		}
		lua_pop(ws->state, 1);
	}
	(void)pthread_mutex_unlock(&(ws->ws_mutex));

	return ok;
}


static int
lua_websocket_ready(struct mg_connection *conn, void *ws_arg)
{
	struct lua_websock_data *ws = (struct lua_websock_data *)(ws_arg);
	int err, ok = 0;

	assert(ws != NULL);
	assert(ws->state != NULL);

	(void)pthread_mutex_lock(&(ws->ws_mutex));

	lua_getglobal(ws->state, "ready");
	lua_newtable(ws->state);
	lua_pushstring(ws->state, "client");
	lua_pushlightuserdata(ws->state, (void *)conn);
	lua_rawset(ws->state, -3);
	err = lua_pcall(ws->state, 1, 1, 0);
	if (err != 0) {
		lua_cry(conn, err, ws->state, ws->script, "ready handler");
	} else {
		if (lua_isboolean(ws->state, -1)) {
			ok = lua_toboolean(ws->state, -1);
		}
		lua_pop(ws->state, 1);
	}

	(void)pthread_mutex_unlock(&(ws->ws_mutex));

	return ok;
}


static void
lua_websocket_close(struct mg_connection *conn, void *ws_arg)
{
	struct lua_websock_data *ws = (struct lua_websock_data *)(ws_arg);
	struct mg_shared_lua_websocket_list **shared_websock_list =
	    &(conn->ctx->shared_lua_websockets);
	int err = 0;
	unsigned i;

	assert(ws != NULL);
	assert(ws->state != NULL);

	(void)pthread_mutex_lock(&(ws->ws_mutex));

	lua_getglobal(ws->state, "close");
	lua_newtable(ws->state);
	lua_pushstring(ws->state, "client");
	lua_pushlightuserdata(ws->state, (void *)conn);
	lua_rawset(ws->state, -3);

	err = lua_pcall(ws->state, 1, 0, 0);
	if (err != 0) {
		lua_cry(conn, err, ws->state, ws->script, "close handler");
	}
	for (i = 0; i < ws->references; i++) {
		if (ws->conn[i] == conn) {
			ws->references--;
			ws->conn[i] = ws->conn[ws->references];
		}
	}
	/* TODO: Delete lua_websock_data and remove it from the websocket list.
	   This must only be done, when all connections are closed, and all
	   asynchronous operations and timers are completed/expired. */
	(void)shared_websock_list; /* shared_websock_list unused (see open TODO) */

	(void)pthread_mutex_unlock(&(ws->ws_mutex));
}
#endif

static void *lib_handle_uuid = NULL;

static void
lua_init_optional_libraries(void)
{
#if !defined(_WIN32)
	lib_handle_uuid = dlopen("libuuid.so", RTLD_LAZY);
	pf_uuid_generate.p = dlsym(lib_handle_uuid, "uuid_generate");
#else
	pf_uuid_generate.p = 0;
#endif
}

static void
lua_exit_optional_libraries(void)
{
#if !defined(_WIN32)
	dlclose(lib_handle_uuid);
#endif
	pf_uuid_generate.p = 0;
	lib_handle_uuid = NULL;
}