Fixes wrong IP address when using a reverse proxy (#2236)

Added reverse proxy support to preserve forwarded IPs

framework/core/src/Http/Exception/ProxyNotAllowedException.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Http\Exception;
+
+use Exception;
+use Flarum\Foundation\KnownError;
+
+class ProxyNotAllowedException extends Exception implements KnownError
+{
+    public function getType(): string
+    {
+        return 'reverse_proxy_not_allowed';
+    }
+}

framework/core/src/Http/Middleware/ProxyAddress.php

@@ -0,0 +1,72 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Http\Middleware;
+
+use Flarum\Http\Exception\ProxyNotAllowedException;
+use Illuminate\Support\Arr;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface as Middleware;
+use Psr\Http\Server\RequestHandlerInterface;
+
+class ProxyAddress implements Middleware
+{
+    /**
+     * @var bool
+     */
+    protected $enabled;
+
+    /**
+     * @var array
+     */
+    protected $allowedAddresses;
+
+    /**
+     * @param bool $enabled
+     * @param array $allowedAddresses
+     */
+    public function __construct($enabled, $allowedAddresses)
+    {
+        $this->enabled = $enabled;
+        $this->allowedAddresses = $allowedAddresses;
+    }
+
+    private function wildcardMatch(string $ipAddress): bool
+    {
+        foreach ($this->allowedAddresses as $allowedAddress) {
+            if (fnmatch($allowedAddress, $ipAddress)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
+    {
+        $serverParams = $request->getServerParams();
+        $ipAddress = Arr::get($serverParams, 'REMOTE_ADDR', '127.0.0.1');
+
+        if ($this->enabled) {
+            if ($this->wildcardMatch($ipAddress)) {
+                // standard header for proxies, see: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For
+                $ipAddress = Arr::get($serverParams, 'X_FORWARDED_FOR', $ipAddress);
+                $ipAddress = Arr::get($serverParams, 'HTTP_CLIENT_IP', $ipAddress);
+                $ipAddress = Arr::get($serverParams, 'X_PROXYUSER_IP', $ipAddress);
+            } else {
+                throw new ProxyNotAllowedException();
+            }
+        }
+
+        $request = $request->withAttribute('ipAddress', $ipAddress);
+
+        return $handler->handle($request);
+    }
+}