rest_client Module


Table of Contents

1. Admin Guide
1.1. Overview
1.2. TCP Connection Reusage
1.3. Dependencies
1.3.1. OpenSIPS Modules
1.3.2. External Libraries or Applications
1.4. Exported Parameters
1.4.1. curl_timeout (integer)
1.4.2. connection_timeout (integer)
1.4.3. connect_poll_interval (integer)
1.4.4. max_async_transfers (integer)
1.4.5. ssl_verifypeer (integer)
1.4.6. ssl_verifyhost (integer)
1.4.7. ssl_capath (integer)
1.4.8. curl_http_version (integer)
1.4.9. enable_expect_100 (boolean)
1.5. Exported Functions
1.5.1. rest_get(url, body_pv, [ctype_pv], [retcode_pv])
1.5.2. rest_post(url, send_body, [send_ctype], recv_body_pv, [recv_ctype_pv], [retcode_pv])
1.5.3. rest_put(url, send_body, [send_ctype], recv_body_pv[, [recv_ctype_pv][, [retcode_pv]]])
1.5.4. rest_append_hf(txt)
1.5.5. rest_init_client_tls(tls_client_domain)
1.6. Exported Asynchronous Functions
1.6.1. rest_get(url, body_pv[, [ctype_pv][, [retcode_pv]]])
1.6.2. rest_post(url, send_body_pv, [send_ctype_pv], recv_body_pv[, [recv_ctype_pv][, [retcode_pv]]])
1.6.3. rest_put(url, send_body_pv, [send_ctype_pv], recv_body_pv[, [recv_ctype_pv][, [retcode_pv]]])
1.7. Exported script transformations
1.7.1. {rest.escape}
1.7.2. {rest.unescape}
2. Contributors
2.1. By Commit Statistics
2.2. By Commit Activity
3. Documentation
3.1. Contributors

List of Tables

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

List of Examples

1.1. Setting the curl_timeout parameter
1.2. Setting the connection_timeout parameter
1.3. Setting the connect_poll_interval parameter
1.4. Setting the max_async_transfers parameter
1.5. Setting the ssl_verifypeer parameter
1.6. Setting the ssl_verifyhost parameter
1.7. Setting the ssl_capath parameter
1.8. Setting the curl_http_version parameter
1.9. Setting the enable_expect_100 parameter
1.10. rest_get usage
1.11. rest_post usage
1.12. rest_put usage
1.13. rest_append_hf usage
1.14. rest_init_client_tls usage
1.15. async rest_get usage
1.16. async rest_post usage
1.17. async rest_put usage
1.18. rest.escape usage
1.19. rest.unescape usage

Chapter1.Admin Guide

1.1.Overview

The rest_client module provides a means of interacting with an HTTP server by doing RESTful queries, such as GET, POST and PUT.

1.2.TCP Connection Reusage

Unless specified otherwise by the server through a "Connection: close" indication, the module will keep and reuse the TCP connections it creates as much as possible, regardless if the script writer performs blocking or asynchronous HTTP requests. These connections are not shared among OpenSIPS workers — each worker maintains its own set of connections.

1.3.Dependencies

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:

  • libcurl.

1.4.Exported Parameters

1.4.1.curl_timeout (integer)

The maximum allowed time for any HTTP(S) transfer to complete. This interval is inclusive of the initial connect time window, hence the value of this parameter must be greater than or equal to connection_timeout.

Default value is 20 seconds.

Example1.1.Setting the curl_timeout parameter

...
modparam("rest_client", "curl_timeout", 10)
...

1.4.2.connection_timeout (integer)

The maximum allowed time to establish a connection with the server.

Default value is 20 seconds.

Example1.2.Setting the connection_timeout parameter

...
modparam("rest_client", "connection_timeout", 4)
...

1.4.3.connect_poll_interval (integer)

Only relevant with async requests. Allows complete control over how quickly we want to detect libcurl's completed blocking TCP/TLS handshakes, so the async transfers can be put in the background. A lower connect_poll_interval may speed up all async HTTP transfers, but will also increase CPU usage.

Default value is 20 milliseconds.

Example1.3.Setting the connect_poll_interval parameter

...
modparam("rest_client", "connect_poll_interval", 2)
...

1.4.4.max_async_transfers (integer)

Maximum number of asynchronous HTTP transfers a single OpenSIPS worker is allowed to run simultaneously. As long as this threshold is reached for a worker, all new async transfers it attempts to perform will be done in a blocking manner, with appropriate logging warnings.

Default value is 100.

Example1.4.Setting the max_async_transfers parameter

...
modparam("rest_client", "max_async_transfers", 300)
...

1.4.5.ssl_verifypeer (integer)

Set this to 0 in order to disable the verification of the remote peer's certificate. Verification is done using a default bundle of CA certificates which come with libcurl.

Default value is 1 (enabled).

Example1.5.Setting the ssl_verifypeer parameter

...
modparam("rest_client", "ssl_verifypeer", 0)
...

1.4.6.ssl_verifyhost (integer)

Set this to 0 in order to disable the verification that the remote peer actually corresponds to the server listed in the certificate.

Default value is 1 (enabled).

Example1.6.Setting the ssl_verifyhost parameter

...
modparam("rest_client", "ssl_verifyhost", 0)
...

1.4.7.ssl_capath (integer)

An optional path for CA certificates to be used for host verifications.

Example1.7.Setting the ssl_capath parameter

...
modparam("rest_client", "ssl_capath", "/home/opensips/ca_certificates")
...

1.4.8.curl_http_version (integer)

Use a specific HTTP version for all requests. Possible values:

  • 0 (default) - use whatever is deemed fit by libcurl

  • 1 - enforce HTTP 1.0 requests

  • 2 - enforce HTTP 1.1 requests

  • 3 - attempt HTTP 2 requests. Fall back to HTTP 1.1 if HTTP 2 cannot be negotiated with the server. Requires libcurl 7.33.0+.

  • 4 - attempt HTTP 2 over TLS (HTTPS) only. Fall back to HTTP 1.1 if HTTP 2 cannot be negotiated with the HTTPS server. For clear text HTTP servers, use HTTP 1.1. Requires libcurl 7.47.0+.

  • 5 - Issue non-TLS HTTP requests using HTTP 2 without HTTP 1.1 Upgrade. It requires prior knowledge that the server supports HTTP 2 straight away. HTTPS requests will still do HTTP/2 the standard way with negotiated protocol version in the TLS handshake. Requires libcurl 7.49.0+.

more details here, where the documentation for this setting was inspired (read: pilfered) from

Example1.8.Setting the curl_http_version parameter

...
modparam("rest_client", "curl_http_version", 3)
...

1.4.9.enable_expect_100 (boolean)

Include a "Expect: 100-continue" HTTP header field whenever the body size of a POST or PUT request exceeds 1024 bytes. Once enabled, the timeout for waiting for a "100 Continue" reply from the server is 1 second, after which the body upload will begin.

Default value is false (disabled).

Example1.9.Setting the enable_expect_100 parameter

...
modparam("rest_client", "enable_expect_100", true)
...

1.5.Exported Functions

1.5.1. rest_get(url, body_pv, [ctype_pv], [retcode_pv])

Perform a blocking HTTP GET on the given url and return a representation of the resource.

Parameters:

  • url (string)

  • body_pv (var) - variable that will hold the body of the HTTP response.

  • ctype_pv (var, optional) - variable thah will contain the value of the "Content-Type:" header of the response.

  • retcode_pv (var, optional) - variable that will retain the status code of the HTTP response. A 0 status code value means no HTTP reply arrived at all.

Return Codes

  • 1 - Success

  • -1 - Connection Refused.

  • -2 - Connection Timeout (the connection_timeout was exceeded before a TCP connection could be established)

  • -3 - Transfer Timeout (the curl_timeout was exceeded before the last byte was received). The retcode_pv may be set to 200 or 0, depending whether a 200 OK was received or not. If it was, the body_pv will contain partially downloaded data, use at your own risk! (we recommend you only use this data for logging / debugging purposes)

  • -10 - Internal Error (out of memory, unexpected libcurl error, etc.)

This function can be used from any route.

Example1.10.rest_get usage

...
# Example of querying a REST service to get the credit of an account
$var(rc) = rest_get("https://getcredit.org/?account=$fU",
                    $var(credit),
                    $var(ct),
                    $var(rcode));
if ($var(rc) < 0) {
	xlog("rest_get() failed with $var(rc), acc=$fU\n");
	send_reply(500, "Server Internal Error");
	exit;
}

if ($var(rcode) != 200) {
	xlog("L_INFO", "rest_get() rcode=$var(rcode), acc=$fU\n");
	send_reply(403, "Forbidden");
	exit;
}
...

1.5.2. rest_post(url, send_body, [send_ctype], recv_body_pv, [recv_ctype_pv], [retcode_pv])

Perform a blocking HTTP POST on the given url.

Note that the send_body parameter can also accept a format-string but it cannot be larger than 1024 bytes. For larger messages, you must build them in a pseudo-variable and pass it to the function.

Parameters:

  • url (string)

  • send_body (string) - The request body.

  • send_ctype (string, optional) - The MIME Content-Type header for the request. The default is "application/x-www-form-urlencoded"

  • recv_body_pv (var) - the variable will hold the body of the HTTP response.

  • recv_ctype_pv (var, optional) - will contain the value of the "Content-Type" header of the response

  • retcode_pv (var, optional) - variable that will retain the status code of the HTTP response. A 0 status code value means no HTTP reply arrived at all.

Return Codes

  • 1 - Success

  • -1 - Connection Refused.

  • -2 - Connection Timeout (the connection_timeout was exceeded before a TCP connection could be established)

  • -3 - Transfer Timeout (the curl_timeout was exceeded before the last byte was received). The retcode_pv may be set to 200 or 0, depending whether a 200 OK was received or not. If it was, the body_pv will contain partially downloaded data, use at your own risk! (we recommend you only use this data for logging / debugging purposes)

  • -10 - Internal Error (out of memory, unexpected libcurl error, etc.)

This function can be used from any route.

Example1.11.rest_post usage

...
# Creating a resource using a RESTful service with an HTTP POST request
$var(rc) = rest_post("https://myserver.org/register_user",
                     $fU, , $var(body), $var(ct), $var(rcode));
if ($var(rc) < 0) {
	xlog("rest_post() failed with $var(rc), user=$fU\n");
	send_reply(500, "Server Internal Error 1");
	exit;
}

if ($var(rcode) != 200) {
	xlog("rest_post() rcode=$var(rcode), user=$fU\n");
	send_reply(500, "Server Internal Error 2");
	exit;
}
...


1.5.3. rest_put(url, send_body, [send_ctype], recv_body_pv[, [recv_ctype_pv][, [retcode_pv]]])

Perform a blocking HTTP PUT on the given url.

Similar to rest_post(), the send_body_pv parameter can also accept a format-string but it cannot be larger than 1024 bytes. For larger messages, you must build them in a pseudo-variable and pass it to the function.

Parameters:

  • url (string)

  • send_body (string) - The request body.

  • send_ctype (string, optional) - The MIME Content-Type header for the request. The default is "application/x-www-form-urlencoded"

  • recv_body_pv (var) - the variable will hold the body of the HTTP response.

  • recv_ctype_pv (var, optional) - will contain the value of the "Content-Type" header of the response

  • retcode_pv (var, optional) - variable that will retain the status code of the HTTP response. A 0 status code value means no HTTP reply arrived at all.

Return Codes

  • 1 - Success

  • -1 - Connection Refused.

  • -2 - Connection Timeout (the connection_timeout was exceeded before a TCP connection could be established)

  • -3 - Transfer Timeout (the curl_timeout was exceeded before the last byte was received). The retcode_pv may be set to 200 or 0, depending whether a 200 OK was received or not. If it was, the body_pv will contain partially downloaded data, use at your own risk! (we recommend you only use this data for logging / debugging purposes)

  • -10 - Internal Error (out of memory, unexpected libcurl error, etc.)

This function can be used from any route.

Example1.12.rest_put usage

...
# Creating/Updating a resource using a RESTful service with an HTTP PUT request
$var(rc) = rest_put("https://myserver.org/users/$fU",
                    $var(userinfo), , $var(body), $var(ct), $var(rcode));
if ($var(rc) < 0) {
	xlog("rest_put() failed with $var(rc), user=$fU\n");
	send_reply(500, "Server Internal Error 3");
	exit;
}

if ($var(rcode) != 200) {
	xlog("rest_put() rcode=$var(rcode), user=$fU\n");
	send_reply(500, "Server Internal Error 4");
	exit;
}
...

1.5.4. rest_append_hf(txt)

Append txt to the HTTP headers of the subsequent request. Multiple headers can be appended by making multiple calls before executing a request.

The contents of txt should adhere to the specification for HTTP headers (ex. Field: Value)

Parameters

  • txt (string)

This function can be used from any route.

Example1.13.rest_append_hf usage

...
# Example of querying a REST service requiring additional headers

rest_append_hf("Authorization: Bearer mF_9.B5f-4.1JqM");
$var(rc) = rest_get("http://getcredit.org/?account=$fU", $var(credit));
...
		

1.5.5. rest_init_client_tls(tls_client_domain)

Force a specific TLS domain to be eventually used during the next request. Refer to the tls_mgm module for additional info regarding TLS client domains.

If using this function, you must also ensure that tls_mgm is loaded and properly configured.

Parameters

  • tls_client_domain (string)

This function can be used from any route.

Example1.14.rest_init_client_tls usage

...
rest_init_client_tls("dom1");
if (!rest_get("https://example.com"))
    xlog("query failed\n");
...
		

1.6.Exported Asynchronous Functions

1.6.1. rest_get(url, body_pv[, [ctype_pv][, [retcode_pv]]])

Perform an asynchronous HTTP GET. This function behaves exactly the same as rest_get() (in terms of input, output and processing), but in a non-blocking manner. Script execution is suspended until the entire content of the HTTP response is available.

Example1.15.async rest_get usage

route {
	...
	async(rest_get("http://getcredit.org/?account=$fU",
	               $var(credit), , $var(rcode)), resume);
}

route [resume] {
	$var(rc) = $rc;
	if ($var(rc) < 0) {
		xlog("async rest_get() failed with $var(rc), acc=$fU\n");
		send_reply(500, "Server Internal Error");
		exit;
	}

	if ($var(rcode) != 200) {
		xlog("L_INFO", "async rest_get() rcode=$var(rcode), acc=$fU\n");
		send_reply(403, "Forbidden");
		exit;
	}

	...
}

1.6.2. rest_post(url, send_body_pv, [send_ctype_pv], recv_body_pv[, [recv_ctype_pv][, [retcode_pv]]])

Perform an asynchronous HTTP POST. This function behaves exactly the same as rest_post() (in terms of input, output and processing), but in a non-blocking manner. Script execution is suspended until the entire content of the HTTP response is available.

Example1.16.async rest_post usage

route {
	...
	async(rest_post("http://myserver.org/register_user",
	                $fU, , $var(body), $var(ct), $var(rcode)), resume);
}

route [resume] {
	$var(rc) = $rc;
	if ($var(rc) < 0) {
		xlog("async rest_post() failed with $var(rc), user=$fU\n");
		send_reply(500, "Server Internal Error 1");
		exit;
	}
	if ($var(rcode) != 200) {
		xlog("async rest_post() rcode=$var(rcode), user=$fU\n");
		send_reply(500, "Server Internal Error 2");
		exit;
	}

	...
}


1.6.3. rest_put(url, send_body_pv, [send_ctype_pv], recv_body_pv[, [recv_ctype_pv][, [retcode_pv]]])

Perform an asynchronous HTTP PUT. This function behaves exactly the same as rest_put() (in terms of input, output and processing), but in a non-blocking manner. Script execution is suspended until the entire content of the HTTP response is available.

Example1.17.async rest_put usage

route {
	...
	async(rest_put("http://myserver.org/users/$fU", $var(userinfo), ,
	               $var(body), $var(ct), $var(rcode)), resume);
}

route [resume] {
	$var(rc) = $rc;
	if ($var(rc) < 0) {
		xlog("async rest_put() failed with $var(rc), user=$fU\n");
		send_reply(500, "Server Internal Error 3");
		exit;
	}
	if ($var(rcode) != 200) {
		xlog("async rest_put() rcode=$var(rcode), user=$fU\n");
		send_reply(500, "Server Internal Error 4");
		exit;
	}

	...
}

1.7.Exported script transformations

The module also provides a way for encoding and decoding parameters contained in a arbitrary script variable, in accordance with RFC3986. This is done by applying a transformation to a script variable containing the data to be encoded. The value of the original variable is not altered and a corresponding string value is returned. The transformation is performed through libcurl API method curl_easy_escape (or curl_escape for libcurl < 7.15.4).

1.7.1. {rest.escape}

The result of this transformation is to produce percent encoded string value which can be safely used in URI construction.

There are no parameters for this transformation.

Example1.18.rest.escape usage

...
# This example would produce log entry: "Output: call%40example.com%26safe%3Dfalse"
$var(tmp) = "call@example.com&safe=false";
xlog("Output: $(var(tmp){rest.escape})\n");

# Encode call ID before transmission:
$var(rc) = rest_get("https://call-info.org/?id=$(ci{rest.escape})", $var(body_pv));
...
                

1.7.2. {rest.unescape}

The result of this transformation is to decode percent encoded string values.

There are no parameters for this transformation.

Example1.19.rest.unescape usage

...
# This example would produce log entry: "Output: 1+1=2!"
$var(tmp) = "1%2B1%3D2%21";
xlog("Output: $(var(tmp){rest.unescape})\n");

# This example would produce log entry: "OpenSIPs, tastes better with every SIP!"
$var(tmp) = "OpenSIPs%2C%20tastes%20better%20with%20every%20SIP%21";
xlog("$(var(tmp){rest.unescape})\n");
...
                

Chapter2.Contributors

2.1.By Commit Statistics

Table2.1.Top contributors by DevScore(1), authored commits(2) and lines added/removed(3)

NameDevScoreCommitsLines ++Lines --
1. Liviu Chircu (@liviuchircu)1236834591585
2. Ionut Ionita (@ionutrazvanionita)2312663262
3. Vlad Patrascu (@rvlad-patrascu)167332341
4. Razvan Crainea (@razvancrainea)15134117
5. Bogdan-Andrei Iancu (@bogdan-iancu)7511447
6. Jarrod Baumann (@jarrodb)6313132
7. Agalya Ramachandran (@AgalyaR)623541
8. Callum Guy (@spacetourist)622818
9. Ryan Bullock (@rrb3942)529177
10. Peter Lemenkov (@lemenkov)3111

All remaining contributors: Andrey Vorobiev (@andrey-vorobiev).

(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/build-contrib.sh. 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

2.2.By Commit Activity

Table2.2.Most recently active contributors(1) to this module

NameCommit Activity
1. Liviu Chircu (@liviuchircu)Mar 2013 - Jul 2020
2. Vlad Patrascu (@rvlad-patrascu)May 2017 - Jun 2020
3. Callum Guy (@spacetourist)Jan 2020 - Jan 2020
4. Razvan Crainea (@razvancrainea)Aug 2015 - Nov 2019
5. Bogdan-Andrei Iancu (@bogdan-iancu)Oct 2014 - Apr 2019
6. Peter Lemenkov (@lemenkov)Jun 2018 - Jun 2018
7. Ionut Ionita (@ionutrazvanionita)Feb 2017 - Mar 2017
8. Andrey Vorobiev (@andrey-vorobiev)Feb 2017 - Feb 2017
9. Ryan Bullock (@rrb3942)Jan 2017 - Jan 2017
10. Agalya Ramachandran (@AgalyaR)Oct 2016 - Oct 2016

All remaining contributors: Jarrod Baumann (@jarrodb).

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

Chapter3.Documentation

3.1.Contributors

Last edited by: Liviu Chircu (@liviuchircu), Callum Guy (@spacetourist), Vlad Patrascu (@rvlad-patrascu), Peter Lemenkov (@lemenkov), Razvan Crainea (@razvancrainea), Agalya Ramachandran (@AgalyaR), Jarrod Baumann (@jarrodb), Bogdan-Andrei Iancu (@bogdan-iancu).

Documentation Copyrights:

Copyright 2013 www.opensips-solutions.com