Read $remote_addr attribute for AccessLogHandler (trusted proxies)

Author: clue

docs/api/app.md

@@ -345,3 +345,76 @@ $app = new FrameworkX\App($container);
 
 $app->run();
 ```
+
+X supports running behind reverse proxies just fine. However, by default it will
+see the IP address of the last proxy server as the client IP address (this will
+often be `127.0.0.1`). You can get the original client IP address if you configure
+your proxy server to forward the original client IP address in the `X-Forwarded-For`
+(XFF) or `Forwarded` HTTP request header. If you want to use these trusted headers,
+you may use a custom middleware to read the IP from this header before passing
+it to the [`AccessLogHandler`](middleware.md#accessloghandler) like this:
+
+=== "Using middleware instances"
+
+    ```php title="public/index.php"
+    <?php
+
+    use Acme\Todo\TrustedProxyMiddleware;
+
+    require __DIR__ . '/../vendor/autoload.php';
+
+    $app = new FrameworkX\App(
+        new TrustedProxyMiddleware(),
+        new FrameworkX\AccessLogHandler(),
+        new FrameworkX\ErrorHandler()
+    );
+
+    // Register routes here, see routing…
+
+    $app->run();
+    ```
+
+=== "Using middleware names"
+
+    ```php title="public/index.php"
+    <?php
+
+    use Acme\Todo\TrustedProxyMiddleware;
+
+    require __DIR__ . '/../vendor/autoload.php';
+
+    $app = new FrameworkX\App(
+        TrustedProxyMiddleware::class,
+        FrameworkX\AccessLogHandler::class,
+        FrameworkX\ErrorHandler::class
+    );
+
+    // Register routes here, see routing…
+
+    $app->run();
+    ```
+
+```php title="src/TrustedProxyMiddleware.php"
+<?php
+
+namespace Acme\Todo;
+
+use Psr\Http\Message\ServerRequestInterface;
+
+class TrustedProxyMiddleware
+{
+    public function __invoke(ServerRequestInterface $request, callable $next)
+    {
+        // use 127.0.0.1 as trusted proxy to read from X-Forwarded-For (XFF)
+        $remote_addr = $request->getAttribute('remote_addr') ?? $request->getServerParams()['REMOTE_ADDR'] ?? null;
+        if ($remote_addr === '127.0.0.1' && $request->hasHeader('X-Forwarded-For')) {
+            $remote_addr = preg_replace('/,.*/', '', $request->getHeaderLine('X-Forwarded-For'));
+            $request = $request->withAttribute('remote_addr', $remote_addr);
+        }
+
+        return $next($request);
+    }
+}
+```
+
+See also [middleware handling](middleware.md) for more details.

src/AccessLogHandler.php

@@ -86,7 +86,7 @@ private function log(ServerRequestInterface $request, ResponseInterface $respons
         }
 
         $this->sapi->log(
-            ($request->getServerParams()['REMOTE_ADDR'] ?? '-') . ' ' .
+            ($request->getAttribute('remote_addr') ?? $request->getServerParams()['REMOTE_ADDR'] ?? '-') . ' ' .
             '"' . $this->escape($method) . ' ' . $this->escape($request->getRequestTarget()) . ' HTTP/' . $request->getProtocolVersion() . '" ' .
             $status . ' ' . $responseSize . ' ' . sprintf('%.3F', $time < 0 ? 0 : $time)
         );

tests/AccessLogHandlerTest.php

@@ -215,6 +215,19 @@ public function testInvokeWithStreamingResponsePrintsNothingIfStreamIsPending()
         $stream->write('hello');
     }
 
+    public function testInvokeWithRemoteAddrAttributePrintsRequestLogWithIpFromAttribute()
+    {
+        $handler = new AccessLogHandler();
+
+        $request = new ServerRequest('GET', 'http://localhost:8080/users', [], '', '1.1', ['REMOTE_ADDR' => '127.0.0.1']);
+        $request = $request->withAttribute('remote_addr', '10.0.0.1');
+        $response = new Response(200, [], "Hello\n");
+
+        // 2021-01-29 12:22:01.717 10.0.0.1 "GET /users HTTP/1.1" 200 6 0.000\n
+        $this->expectOutputRegex("/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d{3} 10\.0\.0\.1 \"GET \/users HTTP\/1\.1\" 200 6 0\.0\d\d" . PHP_EOL . "$/");
+        $handler($request, function () use ($response) { return $response; });
+    }
+
     public function testInvokeWithoutRemoteAddressPrintsRequestLogWithDashAsPlaceholder()
     {
         $handler = new AccessLogHandler();