httpd Module

Table of Contents

1. Admin Guide
1.1. Overview
1.2. Overview
1.3. Dependencies
1.3.1. OpenSIPS Modules
1.3.2. External Libraries or Applications
1.4. Exported Parameters
1.4.1. ip(string)
1.4.2. port(integer)
1.4.3. buf_size (integer)
1.4.4. post_buf_size (integer)
1.4.5. tls_cert_file (string)
1.4.6. tls_key_file (string)
1.4.7. tls_ciphers (string)
1.5. Exported MI Functions
1.5.1. httpd_list_root_path
1.6. Exported Functions
1.7. Known issues
2. Developer Guide
2.1. Available Functions
2.1.1. register_httpdcb (module, root_path, httpd_acces_handler_cb, httpd_flush_data_cb, httpd_init_proc_cb)
3. Contributors
3.1. By Commit Statistics
3.2. By Commit Activity
4. Documentation
4.1. Contributors

List of Tables

3.1. Top contributors by DevScore(1), authored commits(2) and lines added/removed(3)
3.2. Most recently active contributors(1) to this module

List of Examples

1.1. Set ip parameter
1.2. Set port parameter
1.3. Set buf_size parameter
1.4. Set post_buf_size parameter
1.5. Set tls_cert_file parameter
1.6. Set tls_key_file parameter
1.7. Set tls_key_file parameter

Chapter1.Admin Guide


This module provides an HTTP transport layer for OpenSIPS.

Implementation of httpd module's http server is based on libmicrohttpd library.


TLS for the http server is enabled by setting the tls_cert_file and tls_key_file parameters. If this is enabled, support for plain http is disabled.


1.3.1.OpenSIPS Modules

The following modules must be loaded before this module:

  • No dependencies on other OpenSIPS modules.

1.3.2.External Libraries or Applications

The following libraries or applications must be installed before running OpenSIPS with this module loaded:

  • libmicrohttpd, with EPOLL support. This typically means a version newer than 0.9.50.

WARNING! Please be aware about an EPOLL support regression in the libmicrohttpd library and packaging which affects the OpenSIPS httpd module, which was fixed according to the below timeline. The effect of the regression is that the HTTP reply body is sometimes never written by the library, causing the client (e.g. opensips-cli) to hang indefinitely waiting for it:

  • versions 0.9.51 - 0.9.52 have been tested and work correctly

  • regression introduced in 0.9.53 (Apr 2017), lasting until 0.9.71 (May 2020)

  • regression is fixed since 0.9.72 (Dec 2020)

1.4.Exported Parameters


The IP address used by the HTTP server to listen for incoming requests.

The default value is an empty string. If no IP address is set, then the http server will bind to all available IPs.

Example1.1.Set ip parameter

modparam("httpd", "ip", "")


The port number used by the HTTP server to listen for incoming requests.

The default value is 8888. Ports lower than 1024 are not accepted.

Example1.2.Set port parameter

modparam("httpd", "port", 8000)

1.4.3.buf_size (integer)

It specifies the maximum length (in bytes) of the buffer used to write in the html response.

If the size of the buffer is set to zero, it will be automatically set to a quarter of the size of the pkg memory.

The default value is 0.

Example1.3.Set buf_size parameter

modparam("httpd", "buf_size", 524288)

1.4.4.post_buf_size (integer)

It specifies the length (in bytes) of the POST HTTP requests processing buffer. For large POST request, the default value might require to be increased.

The default value is 1024. The minumal value is 256.

Example1.4.Set post_buf_size parameter

modparam("httpd", "post_buf_size", 4096)

1.4.5.tls_cert_file (string)

Public certificate file for httpd. It will be used as server-side certificate for incoming TLS connections.

The default value is ""

Example1.5.Set tls_cert_file parameter

modparam("httpd", "tls_cert_file", "/etc/opensips/tls/server.pem")

1.4.6.tls_key_file (string)

Private key of the above certificate. I must be kept in a safe place with tight permissions!

The default value is ""

Example1.6.Set tls_key_file parameter

modparam("httpd", "tls_key_file", "/etc/opensips/tls/server.key")

1.4.7.tls_ciphers (string)

You can specify the list of algorithms for authentication and encryption that you allow. To obtain a list of ciphers and then choose, use the gnutls-cli application:

  • gnutls-cli -l


Do not use the NULL algorithms (no encryption) ... never!!!

The default value is "SECURE256:+SECURE192:-VERS-ALL:+VERS-TLS1.2"

Example1.7.Set tls_key_file parameter

modparam("httpd", "tls_ciphers", "SECURE256:+SECURE192:-VERS-ALL:+VERS-TLS1.2")

1.5.Exported MI Functions


Lists all the registered http root paths into the httpd module. When a request comes in, if the root parth is in the list, the request will be sent to the module that register it.

Name: httpd_list_root_path

Parameters: none

MI FIFO Command Format:

opensips-cli -x mi httpd_list_root_path

1.6.Exported Functions

No function exported to be used from configuration file.

1.7.Known issues

Due to the fact that OpenSIPS is a multiprocess application, the microhttpd library is used in "external select" mode. This ensures that the library is not running in multithread mode and the library is entirely controled by OpenSIPS. Due to this particular mode of operations, for now, the entire http response is built in a pre-allocated buffer (see buf_size parameter).

Future realeases of this module will address this issue.

Running the http daemon as non root on ports below 1024 is forbidden by default in linux (kernel>=2.6.24). To allow the port binding, one can use setcap to give extra privilleges to opensips binary:

setcap 'cap_net_bind_service=+ep' /usr/local/sbin/opensips

Chapter2.Developer Guide

2.1.Available Functions

2.1.1. register_httpdcb (module, root_path, httpd_acces_handler_cb, httpd_flush_data_cb, httpd_init_proc_cb)

Register a new http root with it's associated callbacks into the httpd module.

Meaning of the parameters is as follows:

  • const char *mod - name of the module that register an http root path to be handled;

  • str *root_path - the registered root path;

  • httpd_acces_handler_cb f1 - handler to the callback method to be called on root path match;

  • httpd_flush_data_cb f2 - handler to the callback method to be called for sending extra data (at a later time);

  • httpd_init_proc_cb f3 - handler to the callback method to be called during httpd process init;


3.1.By Commit Statistics

Table3.1.Top contributors by DevScore(1), authored commits(2) and lines added/removed(3)

NameDevScoreCommitsLines ++Lines --
1. Ovidiu Sas (@ovidiusas)47301667147
2. Razvan Crainea (@razvancrainea)242111868
3. Liviu Chircu (@liviuchircu)17157056
4. Bogdan-Andrei Iancu (@bogdan-iancu)141210354
5. Vlad Patrascu (@rvlad-patrascu)1075289
6. Ionut Ionita (@ionutrazvanionita)866521
7. Fabian Gast (@fgast)411503
8. Stephane Alnet31393
9. Stas Kobzar3122
10. Dusan Klinec (@ph4r05)3111

All remaining contributors: Peter Lemenkov (@lemenkov).

(1) DevScore = author_commits + author_lines_added / (project_lines_added / project_commits) + author_lines_deleted / (project_lines_deleted / project_commits)

(2) including any documentation-related commits, excluding merge commits. Regarding imported patches/code, we do our best to count the work on behalf of the proper owner, as per the "fix_authors" and "mod_renames" arrays in opensips/doc/ If you identify any patches/commits which do not get properly attributed to you, please submit a pull request which extends "fix_authors" and/or "mod_renames".

(3) ignoring whitespace edits, renamed files and auto-generated files

3.2.By Commit Activity

Table3.2.Most recently active contributors(1) to this module

NameCommit Activity
1. Liviu Chircu (@liviuchircu)Mar 2014 - Aug 2022
2. Razvan Crainea (@razvancrainea)Mar 2015 - Oct 2021
3. Bogdan-Andrei Iancu (@bogdan-iancu)Jan 2013 - Aug 2021
4. Fabian Gast (@fgast)Aug 2020 - Aug 2020
5. Vlad Patrascu (@rvlad-patrascu)May 2017 - Apr 2019
6. Ovidiu Sas (@ovidiusas)Jan 2012 - Jan 2019
7. Peter Lemenkov (@lemenkov)Jun 2018 - Jun 2018
8. Ionut Ionita (@ionutrazvanionita)Jan 2017 - Feb 2017
9. Dusan Klinec (@ph4r05)Dec 2015 - Dec 2015
10. Stas KobzarFeb 2015 - Feb 2015

All remaining contributors: Stephane Alnet.

(1) including any documentation-related commits, excluding merge commits



Last edited by: Liviu Chircu (@liviuchircu), Bogdan-Andrei Iancu (@bogdan-iancu), Fabian Gast (@fgast), Razvan Crainea (@razvancrainea), Peter Lemenkov (@lemenkov), Vlad Patrascu (@rvlad-patrascu), Ovidiu Sas (@ovidiusas).

Documentation Copyrights:

Copyright 2012-2013 VoIP Embedded, Inc.