FreePBX AGI script to get a Stir/Shaken Signature via API and apply it to an outgoing call

get_shaken.php

#!/usr/bin/php
<?php

/*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
 *
 * Script: get_shaken.php
 *
 * Latest version: https://gist.github.com/lgaetz/af5849b8984f6ec7aa12a29a01a7e38b
 *
 * Usage: Asterisk AGI file to get a Stir/Shaken signature from Sansay NSS service
 *
 *        AGI(get_shaken.php,source-phone-number,dest-phone-number[,variable-name])
 *
 *           source-phone-number - Outgoing CID for outbound call
 *           dest-phone-number - Destination for the outbound call
 *           variable-name - opt specify channel variable to store sig, default = SSsignature
 *           
 *        use with FreePBX dialplan such as 
 *
 *           [macro-dialout-trunk-predial-hook]
 *           exten => s,1,Noop(Entering user defined context macro-dialout-trunk-predial-hook)
 *           exten => s,n,AGI(get_shaken.php,${CALLERID(num)},${CALLERID(dnid),SSsignature})
 *           exten => s,n,GoSub(func-set-sipheader,s,1(Identity,${SSsignature}))
 *
 * License: GNU/GPL3+
 *
 * History:
 *         2021-05-23   First commit by Lorne Gaetz
 *
 *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***/

// Init vars
$url ="https://your-nss.sansay.com:3334/stir/v1/signing";   // edit to match your Sansay NSS url

// AGI Class
require_once "phpagi.php";
$AGI = new AGI();

if (!isset($argv[2])) {
	agi_verbose('AGI script requires two arguments');
	exit;
} else {
	agi_verbose("Running script with source: ".$argv[1]." and dest: ".$argv[2]);
}

if (isset($argv[3])){
	$channel_var = $argv[3];
} else {
	$channel_var="SSsignature";
}

// Build header array
$Request_ID=substr(md5(rand()), 0, 20);
$headers=array(
	'Content-Type: application/json',
	'Accept: application/json',
	'X-RequestID: '.$Request_ID,
);

// build array of postdata and json encode
$postdata=array (
  'signingRequest' => 
  array (
    'orig' => 
    array (
      'tn' => $argv[1],
    ),
    'dest' => 
    array (
      'tn' => array($argv[2]),
    ),
    'iat' => time(),
  ),
);
$postjson=json_encode($postdata);

agi_verbose('Post data: '.$postjson);

// make API call 
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HTTPHEADER,$headers);
curl_setopt($ch, CURLOPT_POSTFIELDS,$postjson); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

$SSresult = curl_exec($ch);
curl_close($ch);     

$result = json_decode($SSresult,true);
$sig = $result['signingResponse']['identity'];

// remove " chars from returned string
$sig = str_replace('"','',$sig);

agi_verbose('Result: '.$sig);
$AGI->set_variable($channel_var,$sig);	


exit;

function agi_verbose($string, $level=3) {
	global $AGI;
	$AGI->verbose($string, $level);
}