rest_client Module

Liviu Chircu

OpenSIPS Solutions

Edited by

Liviu Chircu

Revision History
Revision $Revision$$Date$

Table of Contents

1. Admin Guide
1.1. Overview
1.2. Dependencies
1.2.1. OpenSIPS Modules
1.2.2. External Libraries or Applications
1.3. Exported Parameters
1.3.1. connection_timeout (integer)
1.3.2. curl_timeout (integer)
1.3.3. ssl_verifypeer (integer)
1.3.4. ssl_verifyhost (integer)
1.3.5. ssl_capath (integer)
1.4. Exported Functions
1.4.1. rest_get(url, body_pv[, [ctype_pv][, [retcode_pv]]])
1.4.2. rest_post(url, send_body_pv, [send_ctype_pv], recv_body_pv[, [recv_ctype_pv][, [retcode_pv]]])
1.4.3. rest_append_hf(txt)
1.5. Exported Asynchronous Functions
1.5.1. rest_get(url, body_pv[, [ctype_pv][, [retcode_pv]]])
1.5.2. rest_post(url, send_body_pv, [send_ctype_pv], recv_body_pv[, [recv_ctype_pv][, [retcode_pv]]])

List of Examples

1.1. Setting the connection_timeout parameter
1.2. Setting the curl_timeout parameter
1.3. Setting the ssl_verifypeer parameter
1.4. Setting the ssl_verifyhost parameter
1.5. Setting the ssl_capath parameter
1.6. rest_get usage
1.7. rest_post usage
1.8. rest_append_hf usage
1.9. async rest_get usage
1.10. async rest_post usage

Chapter 1. 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 and POST.

1.2. Dependencies

1.2.1. OpenSIPS Modules

The following modules must be loaded before this module:

  • No dependencies on other OpenSIPS modules..

1.2.2. External Libraries or Applications

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

  • libcurl.

1.3. Exported Parameters

1.3.1. connection_timeout (integer)

Maximum time allowed to establish a connection with the server.

Default value is “20” seconds.

Example 1.1. Setting the connection_timeout parameter

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

1.3.2. curl_timeout (integer)

Maximum time allowed for the libcurl transfer to complete.

Default value is “20” seconds.

Example 1.2. Setting the curl_timeout parameter

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

1.3.3. 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).

Example 1.3. Setting the ssl_verifypeer parameter

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

1.3.4. 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).

Example 1.4. Setting the ssl_verifyhost parameter

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

1.3.5. ssl_capath (integer)

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

Example 1.5. Setting the ssl_capath parameter

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

1.4. Exported Functions

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

Issues an HTTP GET request to the given 'url', and returns a representation of the resource.

The body_pv pseudo-var will hold the body of the HTTP response.

The optional ctype_pv pseudo-var will contain the value of the "Content-Type:" header.

The optional retcode_pv pseudo-var is used to retain the HTTP status code of the response message. Since the module is based on libcurl, a 0 value means no HTTP reply arrived at all.

Possible parameter types

  • url - String, pseudo-variable, or a String which includes pseudo-variables. (useful for specifying additional attribute-value fields in the URL)

  • body_pv, ctype_pv, retcode_pv - pseudo-variables

This function can be used from the startup, branch, failure, request and timer routes.

Example 1.6. rest_get usage

...
# Example of querying a REST service to get the credit of an account

if (!rest_get("http://getcredit.org/?ruri=$fU", "$var(credit)", "$var(ct)", "$var(rcode)")) {
	xlog("Error code $var(rcode) in HTTP GET!\n");
	send_reply("403", "Not registered");
	exit;
}
...

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

Issues an HTTP POST request to the specified url. The request body will be copied from the send_body_pv pseudo-variable. The MIME Content-Type header for the request will be taken from send_ctype_pv (default is "application/x-www-form-urlencoded")

The mandatory recv_body_pv pseudo-var will hold the body of the HTTP response.

The optional recv_ctype_pv parameter will contain the value of the "Content-Type" header of the response message.

The optional retcode_pv pseudo-var parameter can be given in order to retrieve the HTTP status code of the response message. Since the module based on libcurl, a 0 value means no HTTP reply arrived at all.

Possible parameter types

  • url, send_body_pv, send_type_pv - String, pseudo-variable, or a String which includes pseudo-variables.

  • recv_body_pv, recv_ctype_pv, retcode_pv - pseudo-variables

This function can be used from the startup, branch, failure, request and timer routes.

Example 1.7. rest_post usage

...
# Storing data using a RESTful service with an HTTP POST request

if (!rest_post("http://myserver.org/register_user", "$fU", , "$var(body)", "$var(ct)", "$var(rcode)")) {
	xlog("Error code $var(rcode) in HTTP POST!\n");
	send_reply("403", "POST Forbidden");
	exit;
}
...

1.4.3.  rest_append_hf(txt)

Appends '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)

Parameter types

  • txt - String, pseudo-variable, or a String which includes pseudo-variables. (useful for specifying additional attribute-value fields in the URL)

This function can be used from the startup, branch, failure, request and timer routes.

Example 1.8. rest_append_hf usage

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

rest_append_hf("Authorization: Bearer mF_9.B5f-4.1JqM");
if (!rest_get("http://getcredit.org/?ruri=$fU", "$var(credit)")) {
				...
}
...
		

1.5. Exported Asynchronous Functions

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

Sends a GET HTTP request. This function behaves exactly the same as rest_get (in terms of input, output and processing), but in an asynchronous way. Script execution is suspended until the entire content of the HTTP response if available.

Example 1.9. async rest_get usage

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

route [resume]
{
	if ($rc < 0) {
		xlog("Error code $var(rcode) in HTTP GET!\n");
		send_reply("403", "GET Forbidden");
		exit;
	}
	......
}

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

Sends a POST HTTP request. This function behaves exactly the same as rest_post (in terms of input, output and processing), but in an asynchronous way. Script execution is suspended until the entire content of the HTTP response if available.

Example 1.10. async rest_post usage

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

route [resume]
{
	if ($rc < 0) {
		xlog("Error code $var(rcode) in HTTP POST!\n");
		send_reply("403", "POST Forbidden");
		exit;
	}
	......
}