civetweb/UserManual.md

Overview

Mongoose is small and easy to use web server. It is self-contained, and does not require any external software to run.

On Windows, mongoose iconifies itself to the system tray icon when started. Right-click on the icon pops up a menu, where it is possible to stop mongoose, or configure it, or install it as Windows service. The easiest way to share a folder on Windows is to copy mongoose.exe to a folder, double-click the exe, and launch a browser at http://localhost:8080. Note that 'localhost' should be changed to a machine's name if a folder is accessed from other computer.

On UNIX and Mac, mongoose is a command line utility. Running mongoose in terminal, optionally followed by configuration parameters (mongoose [OPTIONS]) or configuration file name (mongoose [config_file_name]) starts the web server. Mongoose does not detach from terminal. Pressing Ctrl-C keys would stop the server.

When started, mongoose first searches for the configuration file. If configuration file is specified explicitly in the command line, i.e. mongoose path_to_config_file, then specified configuration file is used. Otherwise, mongoose would search for file mongoose.conf in the same directory where binary is located, and use it. Configuration file can be absent.

Configuration file is a sequence of lines, each line containing command line argument name and it's value. Empty lines, and lines beginning with #, are ignored. Here is the example of mongoose.conf file:

document_root c:\www
listening_ports 8080,8043s
ssl_certificate c:\mongoose\ssl_cert.pem

When configuration file is processed, mongoose process command line arguments, if they are specified. Command line arguments therefore can override configuration file settings. Command line arguments must start with -. For example, if mongoose.conf has line document_root /var/www, and mongoose has been started as mongoose -document_root /etc, then /etc directory will be served as document root, because command line options take priority over configuration file. Configuration options section below provide a good overview of Mongoose features.

Mongoose can also be used to modify .htpasswd passwords file:

mongoose -A <htpasswd_file> <realm> <user> <passwd>

Unlike other web servers, mongoose does not require CGI scripts be located in a special directory. CGI scripts can be anywhere. CGI (and SSI) files are recognized by the file name pattern. Mongoose uses shell-like glob patterns. Pattern match starts at the beginning of the string, so essentially patterns are prefix patterns. Syntax is as follows:

 **      Matches everything
 *       Matches everything but slash character, '/'
 ?       Matches any character
 $       Matches the end of the string
 |       Matches if pattern on the left side or the right side matches.

All other characters in the pattern match themselves. Examples:

**.cgi$      Any string that ends with .cgi
/foo         Any string that begins with /foo
**a$|**b$    Any string that ends with a or b

Configuration Options

Below is a list of configuration options Mongoose understands. Every option is followed by it's default value. If default value is not present, then it is empty.

cgi_pattern **.cgi$|**.pl$|**.php$

All files that match cgi_pattern are treated as CGI files. Default pattern allows CGI files be anywhere. To restrict CGIs to a certain directory, use /path/to/cgi-bin/**.cgi as pattern. Note that full file path is matched against the pattern, not the URI.

cgi_environment

Extra environment variables to be passed to the CGI script in addition to standard ones. The list must be comma-separated list of name=value pairs, like this: VARIABLE1=VALUE1,VARIABLE2=VALUE2.

put_delete_passwords_file

Passwords file for PUT and DELETE requests. Without it, PUT and DELETE requests will fail.

cgi_interpreter

Path to an executable to use as CGI interpreter for all CGI scripts regardless script extension. If this option is not set (which is a default), Mongoose looks at first line of a CGI script, shebang line, for an interpreter.

For example, if both PHP and perl CGIs are used, then #!/path/to/php-cgi.exe and #!/path/to/perl.exe must be first lines of the respective CGI scripts. Note that paths should be either full file paths, or file paths relative to the current working directory of mongoose server. If mongoose is started by mouse double-click on Windows, current working directory is a directory where mongoose executable is located.

If all CGIs use the same interpreter, for example they are all PHP, then cgi_interpreter can be set to the path to php-cgi.exe executable and shebang line in the CGI scripts can be omitted. Note that PHP scripts must use php-cgi.exe executable, not php.exe.

protect_uri

Comma separated list of URI=PATH pairs, specifying that given URIs must be protected with respected password files. Paths must be full file paths.

authentication_domain mydomain.com

Authorization realm used in .htpasswd authorization.

ssi_pattern **.shtml$|**.shtm$

All files that match ssi_pattern are treated as SSI. Unknown SSI directives are silently ignored. Currently, two SSI directives are supported, <!--#include ...> and <!--#exec command>. Note that <!--#include ...> directive supports three path specifications:

<!--#include virtual="path">  Path is relative to web server root
<!--#include file="path">     Path is relative to web server working dir
<!--#include "path">          Path is relative to current document

throttle

Limit download speed for clients. throttle is a comma-separated list of key=value pairs, where key could be:

*                   limit speed for all connections
x.x.x.x/mask        limit speed for specified subnet
uri_prefix_pattern  limit speed for given URIs

The value is a floating-point number of bytes per second, optionally followed by a k or m character, meaning kilobytes and megabytes respectively. A limit of 0 means unlimited rate. The last matching rule wins. Examples:

*=1k,10.0.0.0/8=0   limit all accesses to 1 kilobyte per second,
                    but give connections from 10.0.0.0/8 subnet
                    unlimited speed

/downloads/=5k      limit accesses to all URIs in `/downloads/` to
                    5 kilobytes per secods. All other accesses are unlimited

access_log_file

Path to a file for access logs. Either full path, or relative to current working directory. If absent (default), then accesses are not logged.

error_log_file

Path to a file for error logs. Either full path, or relative to current working directory. If absent (default), then errors are not logged.

enable_directory_listing yes

Enable directory listing, either yes or no.

global_passwords_file

Path to a global passwords file, either full path or relative to the current working directory. If set, per-directory .htpasswd files are ignored, and all requests are authorised against that file.

index_files index.html,index.htm,index.cgi,index.shtml,index.php

Comma-separated list of files to be treated as directory index files.

access_control_list

Access Control List (ACL) is a comma separated list of IP subnets, each subnet is prepended by - or + sign. Plus means allow, minus means deny. If subnet mask is omitted, like -1.2.3.4, then it means a single IP address. Mask may vary from 0 to 32 inclusive. On each request, full list is traversed, and last match wins. Default setting is to allow all accesses. Examples:

-0.0.0.0/0,+192.168/16    deny all acccesses, only allow 192.168/16 subnet

extra_mime_types

Extra mime types to recognize, in form extension1=type1,exten- sion2=type2,.... Extension must include dot. Example: .cpp=plain/text,.java=plain/text

listening_ports 8080

Comma-separated list of ports to listen on. If the port is SSL, a letter s must be appeneded, for example, 80,443s will open port 80 and port 443, and connections on port 443 will be SSL-ed. For non-SSL ports, it is allowed to append letter r, meaning 'redirect'. Redirect ports will redirect all their traffic to the first configured SSL port. For example, if listening_ports is 80r,443s, then all HTTP traffic coming at port 80 will be redirected to HTTPS port 443.

It is possible to specify an IP address to bind to. In this case, an IP address and a colon must be prepended to the port number. For example, to bind to a loopback interface on port 80 and to all interfaces on HTTPS port 443, use 127.0.0.1:80,443s.

document_root .

A directory to serve. By default, currect directory is served. Current directory is commonly referenced as dot (.).

ssl_certificate

Path to SSL certificate file. This option is only required when at least one of the listening_ports is SSL.

num_threads 50

Number of worker threads. Mongoose handles each incoming connection in a separate thread. Therefore, the value of this option is effectively a number of concurrent HTTP connections Mongoose can handle.

run_as_user

Switch to given user credentials after startup. Usually, this option is required when mongoose needs to bind on privileged port on UNIX. To do that, mongoose needs to be started as root. But running as root is a bad idea, therefore this option can be used to drop privileges. Example:

mongoose -listening_ports 80 -run_as_user nobody

url_rewrite_patterns

Comma-separated list of URL rewrites in the form of uri_pattern=file_or_directory_path. When Mongoose receives the request, it constructs the file name to show by combining document_root and the URI. However, if the rewrite option is used and uri_pattern matches the requested URI, then document_root is ignored. Insted, file_or_directory_path is used, which should be a full path name or a path relative to the web server's current working directory. Note that uri_pattern, as all mongoose patterns, is a prefix pattern.

This makes it possible to serve many directories outside from document_root, redirect all requests to scripts, and do other tricky things. For example, to redirect all accesses to .doc files to a special script, do:

mongoose -url_rewrite_patterns **.doc$=/path/to/cgi-bin/handle_doc.cgi

Or, to imitate user home directories support, do:

mongoose -url_rewrite_patterns /~joe/=/home/joe/,/~bill=/home/bill/

hide_files_patterns

A pattern for the files to hide. Files that match the pattern will not show up in directory listing and return 404 Not Found if requested. Pattern must be for a file name only, not including directory name.

Common Problems

• PHP doesn't work - getting empty page, or 'File not found' error. The reason for that is wrong paths to the interpreter. Remember that with PHP, correct interpreter is php-cgi.exe (php-cgi on UNIX). Solution: specify full path to the PHP interpreter, e.g.: mongoose -cgi_interpreter /full/path/to/php-cgi

Embedding

Embedding Mongoose is easy. Somewhere in the application code, mg_start() function must be called. That starts the web server in a separate thread. When it is not needed anymore, mg_stop() must be called. Application code can pass configuration options to mg_start(), and also specify callback functions that Mongoose should call at certain events. hello.c provides a minimalistic example.

Common pattern is to implement begin_request callback, and serve static files from memory, and/or construct dynamic replies on the fly. Here is my embed.c gist that shows how to easily any data can be embedded directly into the executable. If such data needs to be encrypted, then encrypted database or encryption dongles would be a better choice.

Other Resources

• Presentation made by Arnout Vandecappelle at FOSDEM 2011 on 2011-02-06 in Brussels, Belgium, called "Creating secure web based user interfaces for Embedded Devices" (pdf | odp)
• Linux Journal article by Michel J.Hammel, 2010-04-01, called Mongoose: an Embeddable Web Server in C