Merge pull request #40 from Wolfgang-check24/fix-protocol-version-check

Fix protocol version check

Author: klapaudius

src/Server/MCPServer.php

@@ -205,7 +205,10 @@ public function initialize(InitializeData $data): InitializeResource
 
         $this->initialized = true;
 
-        $protocolVersion = $data->protocolVersion ?? MCPProtocolInterface::PROTOCOL_VERSION_SSE;
+        // Validate and determine the protocol version to use
+        $requestedProtocolVersion = $data->protocolVersion ?? MCPProtocolInterface::PROTOCOL_VERSION_SSE;
+        $protocolVersion = $this->getValidatedProtocolVersion($requestedProtocolVersion);
+        
         $hasSamplingCapability = isset($data->capabilities['sampling']);
         $this->protocol->setClientSamplingCapability($hasSamplingCapability);
 
@@ -217,6 +220,36 @@ public function initialize(InitializeData $data): InitializeResource
         );
     }
 
+    /**
+     * Validates the requested protocol version and returns a supported version.
+     * 
+     * @param string $requestedVersion The protocol version requested by the client
+     * @return string A supported protocol version
+     * @throws JsonRpcErrorException If the requested protocol version is not supported
+     */
+    private function getValidatedProtocolVersion(string $requestedVersion): string
+    {
+        $supportedVersions = [
+            MCPProtocolInterface::PROTOCOL_VERSION_SSE,
+            MCPProtocolInterface::PROTOCOL_VERSION_STREAMABE_HTTP,
+        ];
+
+        // If the requested version is supported, return it
+        if (in_array($requestedVersion, $supportedVersions, true)) {
+            return $requestedVersion;
+        }
+
+        // Throw error for unsupported protocol version
+        throw new JsonRpcErrorException(
+            message: 'Unsupported protocol version',
+            code: JsonRpcErrorCode::INVALID_PARAMS,
+            data: [
+                'supported' => $supportedVersions,
+                'requested' => $requestedVersion,
+            ]
+        );
+    }
+
     /**
      * Forwards a request message to a specific client via the protocol handler.
      * Used for server-initiated requests to the client (if supported by the protocol/transport).

tests/Server/MCPServerTest.php

@@ -542,4 +542,37 @@ public function test_initialize_sets_client_sampling_capability_when_enabled():
         $this->assertSame(['mock-capability' => true], $initializeResource->capabilities);
         $this->assertEquals($serverInfo, $initializeResource->serverInfo);
     }
+
+    /**
+     * Tests that the initialize method throws an exception for unsupported protocol versions
+     */
+    public function test_initialize_throws_exception_for_unsupported_protocol_version(): void
+    {
+        // Arrange
+        $mockProtocol = $this->createMock(MCPProtocolInterface::class);
+        $serverInfo = ['name' => 'TestServer', 'version' => '1.0'];
+        $mockCapabilities = $this->createMock(ServerCapabilitiesInterface::class);
+
+        $mockProgressNotifierRepository = $this->createMock(ProgressNotifierRepository::class);
+        $server = MCPServer::create($mockProtocol, $mockProgressNotifierRepository, $serverInfo['name'], $serverInfo['version'], $mockCapabilities);
+        $unsupportedVersion = '2025-12-01';
+        $initializeData = new InitializeData('2.0', ['mock-capability' => true], $unsupportedVersion);
+
+        // Act & Assert
+        try {
+            $server->initialize($initializeData);
+            $this->fail('Expected JsonRpcErrorException not thrown');
+        } catch (JsonRpcErrorException $e) {
+            $this->assertEquals(-32602, $e->getJsonRpcErrorCode());
+            $this->assertEquals('Unsupported protocol version', $e->getMessage());
+            
+            $errorData = $e->getErrorData();
+            $this->assertIsArray($errorData);
+            $this->assertArrayHasKey('supported', $errorData);
+            $this->assertArrayHasKey('requested', $errorData);
+            $this->assertEquals($unsupportedVersion, $errorData['requested']);
+            $this->assertContains(MCPProtocolInterface::PROTOCOL_VERSION_SSE, $errorData['supported']);
+            $this->assertContains(MCPProtocolInterface::PROTOCOL_VERSION_STREAMABE_HTTP, $errorData['supported']);
+        }
+    }
 }