Código de estado AJAX 0 con proxy php

Tengo esta aplicación web ajax que estoy desarrollando que básicamente llama a la API de Google api usando ajax y devuelve el resultado para hacer algo con ellos. Sé que AJAX no puede realizar solicitudes de dominios cruzados por sí mismo, así que también puse un proxy de php basado en servidor web usando cURL para tomar las URL, realizar la solicitud y devolver los datos. El problema que tengo es que no importa lo que hago, cada solicitud que hago regresa en un código de estado Http de 0. No estoy del todo seguro de lo que realmente significa un código de 0, pero creo que tiene algo que ver con una conexión fallida . Aquí hay algunos de mis códigos:

function populate() { var number = parseInt('93683',16); var url='https://www.googleapis.com/moderator/v1/series/'+number+'?key='+superkey; var xhttp = null; xhttp = new XMLHttpRequest(); xhttp.onreadystatechange=function() { if (xhttp.readyState==4 && xhttp.status==200) { data = xhttp.responseText; data = data.slice(data.indexOf('{')); data = jQuery.parseJSON(data); alert(data.contents); } else { alert('Error: '+xhttp.status); } } xhttp.open("GET",base_url+url,true); xhttp.send(null); } 

Lo que está sucediendo es que envío la solicitud y el siguiente archivo php la recibe y envía una solicitud.

  // Script: Simple PHP Proxy: Get external HTML, JSON and more! // // *Version: 1.6, Last updated: 1/24/2009* // // Project Home - http://benalman.com/projects/php-simple-proxy/ // GitHub - http://github.com/cowboy/php-simple-proxy/ // Source - http://github.com/cowboy/php-simple-proxy/raw/master/ba-simple-proxy.php // // About: License // // Copyright (c) 2010 "Cowboy" Ben Alman, // Dual licensed under the MIT and GPL licenses. // http://benalman.com/about/license/ // // About: Examples // // This working example, complete with fully commented code, illustrates one way // in which this PHP script can be used. // // Simple - http://benalman.com/code/projects/php-simple-proxy/examples/simple/ // // About: Release History // // 1.6 - (1/24/2009) Now defaults to JSON mode, which can now be changed to // native mode by specifying ?mode=native. Native and JSONP modes are // disabled by default because of possible XSS vulnerability issues, but // are configurable in the PHP script along with a url validation regex. // 1.5 - (12/27/2009) Initial release // // Topic: GET Parameters // // Certain GET (query string) parameters may be passed into ba-simple-proxy.php // to control its behavior, this is a list of these parameters. // // url - The remote URL resource to fetch. Any GET parameters to be passed // through to the remote URL resource must be urlencoded in this parameter. // mode - If mode=native, the response will be sent using the same content // type and headers that the remote URL resource returned. If omitted, the // response will be JSON (or JSONP).  and  // are disabled by default, see  for more information. // callback - If specified, the response JSON will be wrapped in this named // function call. This parameter and  are disabled by // default, see  for more information. // user_agent - This value will be sent to the remote URL request as the // `User-Agent:` HTTP request header. If omitted, the browser user agent // will be passed through. // send_cookies - If send_cookies=1, all cookies will be forwarded through to // the remote URL request. // send_session - If send_session=1 and send_cookies=1, the SID cookie will be // forwarded through to the remote URL request. // full_headers - If a JSON request and full_headers=1, the JSON response will // contain detailed header information. // full_status - If a JSON request and full_status=1, the JSON response will // contain detailed cURL status information, otherwise it will just contain // the `http_code` property. // // Topic: POST Parameters // // All POST parameters are automatically passed through to the remote URL // request. // // Topic: JSON requests // // This request will return the contents of the specified url in JSON format. // // Request: // // > ba-simple-proxy.php?url=http://example.com/ // // Response: // // > { "contents": "...", "headers": {...}, "status": {...} } // // JSON object properties: // // contents - (String) The contents of the remote URL resource. // headers - (Object) A hash of HTTP headers returned by the remote URL // resource. // status - (Object) A hash of status codes returned by cURL. // // Topic: JSONP requests // // This request will return the contents of the specified url in JSONP format // (but only if $enable_jsonp is enabled in the PHP script). // // Request: // // > ba-simple-proxy.php?url=http://example.com/&callback=foo // // Response: // // > foo({ "contents": "...", "headers": {...}, "status": {...} }) // // JSON object properties: // // contents - (String) The contents of the remote URL resource. // headers - (Object) A hash of HTTP headers returned by the remote URL // resource. // status - (Object) A hash of status codes returned by cURL. // // Topic: Native requests // // This request will return the contents of the specified url in the format it // was received in, including the same content-type and other headers (but only // if $enable_native is enabled in the PHP script). // // Request: // // > ba-simple-proxy.php?url=http://example.com/&mode=native // // Response: // // > ... // // Topic: Notes // // * Assumes magic_quotes_gpc = Off in php.ini // // Topic: Configuration Options // // These variables can be manually edited in the PHP file if necessary. // // $enable_jsonp - Only enable  if you really need to. If you // install this script on the same server as the page you're calling it // from, plain JSON will work. Defaults to false. // $enable_native - You can enable , but you should only do // this if you also whitelist specific URLs using $valid_url_regex, to avoid // possible XSS vulnerabilities. Defaults to false. // $valid_url_regex - This regex is matched against the url parameter to // ensure that it is valid. This setting only needs to be used if either // $enable_jsonp or $enable_native are enabled. Defaults to '/.*/' which // validates all URLs. // // ############################################################################ // Change these configuration options if needed, see above descriptions for info. $enable_jsonp = false; $enable_native = false; $valid_url_regex = '/.*/'; // ############################################################################ $url = $_GET['url']; if ( !$url ) { // Passed url not specified. $contents = 'ERROR: url not specified'; $status = array( 'http_code' => 'ERROR' ); } else if ( !preg_match( $valid_url_regex, $url ) ) { // Passed url doesn't match $valid_url_regex. $contents = 'ERROR: invalid url'; $status = array( 'http_code' => 'ERROR' ); } else { $ch = curl_init( $url ); if ( strtolower($_SERVER['REQUEST_METHOD']) == 'post' ) { curl_setopt( $ch, CURLOPT_POST, true ); curl_setopt( $ch, CURLOPT_POSTFIELDS, $_POST ); } if ( $_GET['send_cookies'] ) { $cookie = array(); foreach ( $_COOKIE as $key => $value ) { $cookie[] = $key . '=' . $value; } if ( $_GET['send_session'] ) { $cookie[] = SID; } $cookie = implode( '; ', $cookie ); curl_setopt( $ch, CURLOPT_COOKIE, $cookie ); } curl_setopt( $ch, CURLOPT_FOLLOWLOCATION, true ); curl_setopt( $ch, CURLOPT_HEADER, true ); curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true ); curl_setopt( $ch, CURLOPT_USERAGENT, $_GET['user_agent'] ? $_GET['user_agent'] : $_SERVER['HTTP_USER_AGENT'] ); list( $header, $contents ) = preg_split( '/([\r\n][\r\n])\\1/', curl_exec( $ch ), 2 ); $status = curl_getinfo( $ch ); curl_close( $ch ); } // Split header text into an array. $header_text = preg_split( '/[\r\n]+/', $header ); if ( $_GET['mode'] == 'native' ) { if ( !$enable_native ) { $contents = 'ERROR: invalid mode'; $status = array( 'http_code' => 'ERROR' ); } // Propagate headers to response. foreach ( $header_text as $header ) { if ( preg_match( '/^(?:Content-Type|Content-Language|Set-Cookie):/i', $header ) ) { header( $header ); } } print $contents; } else { // $data will be serialized into JSON data. $data = array(); // Propagate all HTTP headers into the JSON data object. if ( $_GET['full_headers'] ) { $data['headers'] = array(); foreach ( $header_text as $header ) { preg_match( '/^(.+?):\s+(.*)$/', $header, $matches ); if ( $matches ) { $data['headers'][ $matches[1] ] = $matches[2]; } } } // Propagate all cURL request / response info to the JSON data object. if ( $_GET['full_status'] ) { $data['status'] = $status; } else { $data['status'] = array(); $data['status']['http_code'] = $status['http_code']; } // Set the JSON data object contents, decoding it from JSON if possible. $decoded_json = json_decode( $contents ); $data['contents'] = $decoded_json ? $decoded_json : $contents; // Generate appropriate content-type header. $is_xhr = strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest'; header( 'Content-type: application/' . ( $is_xhr ? 'json' : 'x-javascript' ) ); // Get JSONP callback. $jsonp_callback = $enable_jsonp && isset($_GET['callback']) ? $_GET['callback'] : null; // Generate JSON/JSONP string $json = json_encode( $data ); print $jsonp_callback ? "$jsonp_callback($json)" : $json; } ?> 

Mi respuesta del script php dice que el código de estado es 0 y que el contenido es nulo, pero si hago un simple xmlhttp.status dice 200. Este problema me ha frustrado durante una semana. ¿Es el problema con el script PHP o mi ajax, o qué?

En tu ajax nunca llamas a ningún código interno.

Parece que solo llamas desde la URL: 'https://www.googleapis.com/moderator/v1/series/'+number+'?key='+superkey

Descubrí que el problema era que no puedes usar un proxy php en un servidor localhost. Debe estar alojado en un servidor real que pueda comunicarse con otros servidores externos. Al hacer esto, me permite hacer solicitudes de dominio cruzado cuando me plazca, pero me limita a solo solicitudes POST y GET.