Workaround for IP resolution from x-Forwarded-For with multiple proxies

module/Core/test/Middleware/ReverseForwardedAddressesMiddlewareDecoratorTest.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ShlinkioTest\Shlink\Core\Middleware;
+
+use Laminas\Diactoros\Response;
+use Laminas\Diactoros\ServerRequestFactory;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Shlinkio\Shlink\Core\Middleware\ReverseForwardedAddressesMiddlewareDecorator;
+
+class ReverseForwardedAddressesMiddlewareDecoratorTest extends TestCase
+{
+    private ReverseForwardedAddressesMiddlewareDecorator $middleware;
+    private MockObject & MiddlewareInterface $decoratedMiddleware;
+    private MockObject & RequestHandlerInterface $requestHandler;
+
+    protected function setUp(): void
+    {
+        $this->decoratedMiddleware = $this->createMock(MiddlewareInterface::class);
+        $this->requestHandler = $this->createMock(RequestHandlerInterface::class);
+        $this->middleware = new ReverseForwardedAddressesMiddlewareDecorator($this->decoratedMiddleware);
+    }
+
+    #[Test]
+    public function processesRequestAsIsWhenHeadersIsNotFound(): void
+    {
+        $request = ServerRequestFactory::fromGlobals();
+        $this->decoratedMiddleware->expects($this->once())->method('process')->with(
+            $request,
+            $this->requestHandler,
+        )->willReturn(new Response());
+
+        $this->middleware->process($request, $this->requestHandler);
+    }
+
+    #[Test]
+    public function revertsListOfAddressesWhenHeaderIsFound(): void
+    {
+        $request = ServerRequestFactory::fromGlobals()->withHeader(
+            ReverseForwardedAddressesMiddlewareDecorator::FORWARDED_FOR_HEADER,
+            '1.2.3.4,5.6.7.8,9.10.11.12',
+        );
+
+        $this->decoratedMiddleware->expects($this->once())->method('process')->with(
+            $this->callback(fn (ServerRequestInterface $req): bool => $req->getHeaderLine(
+                ReverseForwardedAddressesMiddlewareDecorator::FORWARDED_FOR_HEADER,
+            ) === '9.10.11.12,5.6.7.8,1.2.3.4'),
+            $this->requestHandler,
+        )->willReturn(new Response());
+
+        $this->middleware->process($request, $this->requestHandler);
+    }
+}