Add proxy for AJAX requests

diff --git a/skate-proxy.php b/skate-proxy.php
new file mode 100644 (file)
index 0000000..6ef1309
--- /dev/null
+++ b/skate-proxy.php
@@ -0,0 +1,128 @@
+<?php
+
+/**
+ * AJAX Cross Domain (PHP) Proxy 0.7
+ *    by Iacovos Constantinou (http://www.iacons.net)
+ * 
+ * Released under CC-GNU GPL
+ */
+
+/**
+ * Enables or disables filtering for cross domain requests.
+ * Recommended value: true
+ */
+define( 'CSAJAX_FILTERS', true );
+
+/**
+ * If set to true, $valid_requests should hold only domains i.e. a.example.com, b.example.com, usethisdomain.com
+ * If set to false, $valid_requests should hold the whole URL ( without the parameters ) i.e. http://example.com/this/is/long/url/
+ * Recommended value: false (for security reasons - do not forget that anyone can access your proxy)
+ */
+define( 'CSAJAX_FILTER_DOMAIN', false );
+
+/**
+ * Set debugging to true to receive additional messages - really helpful on development
+ */
+define( 'CSAJAX_DEBUG', true );
+
+/**
+ * A set of valid cross domain requests
+ */
+$valid_requests = array(
+  'http://skate.zurb.com/api/v1/raw'
+);
+
+/* * * STOP EDITING HERE UNLESS YOU KNOW WHAT YOU ARE DOING * * */
+
+// identify request headers
+$request_headers = array( );
+foreach ( $_SERVER as $key => $value ) {
+  if ( substr( $key, 0, 5 ) == 'HTTP_' ) {
+    $headername = str_replace( '_', ' ', substr( $key, 5 ) );
+    $headername = str_replace( ' ', '-', ucwords( strtolower( $headername ) ) );
+    if ( !in_array( $headername, array( 'Host', 'X-Proxy-Url' ) ) ) {
+      $request_headers[] = "$headername: $value";
+    }
+  }
+}
+
+// identify request method, url and params
+$request_method = $_SERVER['REQUEST_METHOD'];
+$request_params = ( $request_method == 'GET' ) ? $_GET : $_POST;
+// Get URL from `csurl` in GET or POST data, before falling back to X-Proxy-URL header.
+$request_url = urldecode( isset( $_REQUEST['csurl'] ) ? $_REQUEST['csurl'] : $_SERVER['HTTP_X_PROXY_URL'] );
+$p_request_url = parse_url( $request_url );
+unset( $request_params['csurl'] );
+
+// ignore requests for proxy :)
+if ( preg_match( '!' . $_SERVER['SCRIPT_NAME'] . '!', $request_url ) || empty( $request_url ) || count( $p_request_url ) == 1 ) {
+  csajax_debug_message( 'Invalid request - make sure that csurl variable is not empty' );
+  exit;
+}
+
+// check against valid requests
+if ( CSAJAX_FILTERS ) {
+  $parsed = $p_request_url;
+  if ( CSAJAX_FILTER_DOMAIN ) {
+    if ( !in_array( $parsed['host'], $valid_requests ) ) {
+      csajax_debug_message( 'Invalid domain - ' . $parsed['host'] . ' does not included in valid requests' );
+      exit;
+    }
+  } else {
+    $check_url = isset( $parsed['scheme'] ) ? $parsed['scheme'] . '://' : '';
+    $check_url .= isset( $parsed['user'] ) ? $parsed['user'] . ($parsed['pass'] ? ':' . $parsed['pass'] : '') . '@' : '';
+    $check_url .= isset( $parsed['host'] ) ? $parsed['host'] : '';
+    $check_url .= isset( $parsed['port'] ) ? ':' . $parsed['port'] : '';
+    $check_url .= isset( $parsed['path'] ) ? $parsed['path'] : '';
+    if ( !in_array( $check_url, $valid_requests ) ) {
+      csajax_debug_message( 'Invalid domain - ' . $request_url . ' does not included in valid requests' );
+      exit;
+    }
+  }
+}
+
+// append query string for GET requests
+if ( $request_method == 'GET' && count( $request_params ) > 0 && (!array_key_exists( 'query', $p_request_url ) || empty( $p_request_url['query'] ) ) ) {
+  $request_url .= '?' . http_build_query( $request_params );
+}
+
+// let the request begin
+$ch = curl_init( $request_url );
+curl_setopt( $ch, CURLOPT_HTTPHEADER, $request_headers );   // (re-)send headers
+curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );  // return response
+curl_setopt( $ch, CURLOPT_HEADER, true );    // enabled response headers
+// add post data for POST requests
+if ( $request_method == 'POST' ) {
+  curl_setopt( $ch, CURLOPT_POST, true );
+  curl_setopt( $ch, CURLOPT_POSTFIELDS, http_build_query( $request_params ) );
+}
+
+// retrieve response (headers and content)
+$response = curl_exec( $ch );
+curl_close( $ch );
+
+// split response to header and content
+list($response_headers, $response_content) = preg_split( '/(\r\n){2}/', $response, 2 );
+
+// (re-)send the headers
+$response_headers = preg_split( '/(\r\n){1}/', $response_headers );
+foreach ( $response_headers as $key => $response_header ) {
+  // Rewrite the `Location` header, so clients will also use the proxy for redirects.
+  if ( preg_match( '/^Location:/', $response_header ) ) {
+    list($header, $value) = preg_split( '/: /', $response_header, 2 );
+    $response_header = 'Location: ' . $_SERVER['REQUEST_URI'] . '?csurl=' . $value;
+  }
+  if ( !preg_match( '/^(Transfer-Encoding):/', $response_header ) ) {
+    header( $response_header );
+  }
+}
+
+// finally, output the content
+print($response_content );
+
+function csajax_debug_message( $message )
+{
+  if ( true == CSAJAX_DEBUG ) {
+    print $message . PHP_EOL;
+  }
+}
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