Support communication over Unix domain sockets (UDS)

README.md

@@ -14,6 +14,7 @@ built on top of [ReactPHP](https://reactphp.org).
     * [DNS resolution](#dns-resolution)
     * [Authentication](#authentication)
     * [Advanced secure proxy connections](#advanced-secure-proxy-connections)
+    * [Advanced Unix domain sockets](#advanced-unix-domain-sockets)
 * [Install](#install)
 * [Tests](#tests)
 * [License](#license)
@@ -287,6 +288,42 @@ $proxy = new ProxyConnector('https://127.0.0.1:443', $connector);
 $proxy->connect('tcp://smtp.googlemail.com:587');
 ```
 
+#### Advanced Unix domain sockets
+
+HTTP CONNECT proxy servers support forwarding TCP/IP based connections and
+higher level protocols.
+In some advanced cases, it may be useful to let your HTTP CONNECT proxy server
+listen on a Unix domain socket (UDS) path instead of a IP:port combination.
+For example, this allows you to rely on file system permissions instead of
+having to rely on explicit [authentication](#authentication).
+
+You can simply use the `http+unix://` URI scheme like this:
+
+```php
+$proxy = new ProxyConnector('http+unix:///tmp/proxy.sock', $connector);
+
+$proxy->connect('tcp://google.com:80')->then(function (ConnectionInterface $stream) {
+    // connected…
+});
+```
+
+Similarly, you can also combine this with [authentication](#authentication)
+like this:
+
+```php
+$proxy = new ProxyConnector('http+unix://user:pass@/tmp/proxy.sock', $connector);
+```
+
+> Note that Unix domain sockets (UDS) are considered advanced usage and PHP only
+  has limited support for this.
+  In particular, enabling [secure TLS](#secure-tls-connections) may not be
+  supported.
+
+> Note that the HTTP CONNECT protocol does not support the notion of UDS paths.
+  The above works reasonably well because UDS is only used for the connection between
+  client and proxy server and the path will not actually passed over the protocol.
+  This implies that this does not support connecting to UDS destination paths.
+
 ## Install
 
 The recommended way to install this library is [through Composer](https://getcomposer.org).

composer.json

@@ -18,8 +18,8 @@
     },
     "require": {
         "php": ">=5.3",
-        "react/socket": "^1.0 || ^0.8 || ^0.7.1",
         "react/promise": " ^2.1 || ^1.2.1",
+        "react/socket": "^1.0 || ^0.8.4",
         "ringcentral/psr7": "^1.2"
     },
     "require-dev": {

src/ProxyConnector.php

@@ -2,14 +2,15 @@
 
 namespace Clue\React\HttpProxy;
 
-use React\Socket\ConnectorInterface;
 use Exception;
 use InvalidArgumentException;
 use RuntimeException;
 use RingCentral\Psr7;
 use React\Promise;
 use React\Promise\Deferred;
 use React\Socket\ConnectionInterface;
+use React\Socket\ConnectorInterface;
+use React\Socket\FixedUriConnector;
 
 /**
  * A simple Connector that uses an HTTP CONNECT proxy to create plain TCP/IP connections to any destination
@@ -57,13 +58,25 @@ class ProxyConnector implements ConnectorInterface
      */
     public function __construct($proxyUrl, ConnectorInterface $connector)
     {
+        // support `http+unix://` scheme for Unix domain socket (UDS) paths
+        if (preg_match('/^http\+unix:\/\/(.*?@)?(.+?)$/', $proxyUrl, $match)) {
+            // rewrite URI to parse authentication from dummy host
+            $proxyUrl = 'http://' . $match[1] . 'localhost';
+
+            // connector uses Unix transport scheme and explicit path given
+            $connector = new FixedUriConnector(
+                'unix://' . $match[2],
+                $connector
+            );
+        }
+
         if (strpos($proxyUrl, '://') === false) {
             $proxyUrl = 'http://' . $proxyUrl;
         }
 
         $parts = parse_url($proxyUrl);
         if (!$parts || !isset($parts['scheme'], $parts['host']) || ($parts['scheme'] !== 'http' && $parts['scheme'] !== 'https')) {
-            throw new InvalidArgumentException('Invalid proxy URL');
+            throw new InvalidArgumentException('Invalid proxy URL "' . $proxyUrl . '"');
         }
 
         // apply default port and TCP/TLS transport for given scheme

tests/ProxyConnectorTest.php

@@ -31,6 +31,14 @@ public function testInvalidProxyScheme()
         new ProxyConnector('ftp://example.com', $this->connector);
     }
 
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testInvalidHttpsUnixScheme()
+    {
+        new ProxyConnector('https+unix:///tmp/proxy.sock', $this->connector);
+    }
+
     public function testCreatesConnectionToHttpPort()
     {
         $promise = new Promise(function () { });
@@ -71,6 +79,16 @@ public function testCreatesConnectionToHttpsPort()
         $proxy->connect('google.com:80');
     }
 
+    public function testCreatesConnectionToUnixPath()
+    {
+        $promise = new Promise(function () { });
+        $this->connector->expects($this->once())->method('connect')->with('unix:///tmp/proxy.sock')->willReturn($promise);
+
+        $proxy = new ProxyConnector('http+unix:///tmp/proxy.sock', $this->connector);
+
+        $proxy->connect('google.com:80');
+    }
+
     public function testCancelPromiseWillCancelPendingConnection()
     {
         $promise = new Promise(function () { }, $this->expectCallableOnce());
@@ -140,6 +158,19 @@ public function testWillProxyAuthorizationHeaderIfProxyUriContainsAuthentication
         $proxy->connect('google.com:80');
     }
 
+    public function testWillProxyAuthorizationHeaderIfUnixProxyUriContainsAuthentication()
+    {
+        $stream = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(array('close', 'write'))->getMock();
+        $stream->expects($this->once())->method('write')->with("CONNECT google.com:80 HTTP/1.1\r\nHost: google.com:80\r\nProxy-Authorization: Basic dXNlcjpwYXNz\r\n\r\n");
+
+        $promise = \React\Promise\resolve($stream);
+        $this->connector->expects($this->once())->method('connect')->with('unix:///tmp/proxy.sock')->willReturn($promise);
+
+        $proxy = new ProxyConnector('http+unix://user:pass@/tmp/proxy.sock', $this->connector);
+
+        $proxy->connect('google.com:80');
+    }
+
     public function testRejectsInvalidUri()
     {
         $this->connector->expects($this->never())->method('connect');