How do I access a php file from another domain - php

Question

Say I got 3 websites. Every time I do an action on site (1), I need to access file.php from (2) and (3) with the parameter of the site the action has been done ( (1) in this case ), so, for this example, I need to access:
(2).com/file.php?site=1
(3).com/file.php?site=1
The same applies if the action is done from the website (2) and (3).
What is the best way to approach this? ( I don't want to manually access the file from my browser every time said action happens on the website (x) )
I tried doing a simple:
<form method="get" action="(2).com/file.php?site=1"> </form>
<form method="get" action="(3).com/file.php?site=1"> </form>
It doesn't work.
I tried doing some kind of ajax/XMLHttpRequest and also tried using the "file" PHP function.
So, my question is, how do I approach this? What is the best way to "virtually" open a browser, and load a PHP file?

Answer 1

Use curl via a proxy for cross-domain queries.
Here's an example taken from another SO question ( How to use CURL via a proxy? )
<?php
$url = 'http://www.php.net';
$proxy = '10.10.10.101:8080';
//$proxyauth = 'user:password';
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_PROXY, $proxy);
//curl_setopt($ch, CURLOPT_PROXYUSERPWD, $proxyauth);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, 1);
$curl_scraped_page = curl_exec($ch);
curl_close($ch);
echo $curl_scraped_page;

Answer 2

I'm sorry because I haven't used the Search function enough :(
I would've tried curl, but the code Prefix used didn't work on my site and when I tried it locally, it said that curl was not installed, so I proceeded to try the next thing that was in sight. I ended up using this code, from another SO thread: How do I send a POST request with PHP?
$url = 'http://server.com/path';
$data = array('key1' => 'value1', 'key2' => 'value2');
// use key 'http' even if you send the request to https://...
$options = array(
'http' => array(
'header' => "Content-type: application/x-www-form-urlencoded\r\n",
'method' => 'POST',
'content' => http_build_query($data),
),
);
$context = stream_context_create($options);
$result = file_get_contents($url, false, $context);
var_dump($result)

Answer 3

You can use PHP files from other domains normally (to handle requests, echo results etc.), but you need to add the following headers to the PHP files on your other domains. This is needed for ajax or xmlhttprequests.
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Headers: *");