Implement SSH Phase 13.3: Channel.rs support for port forwarding channels

- Modify Channel struct to add direct_tcpip and forwarded_tcpip fields
- Modify handle_channel_open to support 'direct-tcpip' and 'forwarded-tcpip' channel types
- Add handle_session_channel_open() function (Phase 6)
- Add handle_direct_tcpip_channel_open() function (Phase 13.3: Remote port forwarding)
- Add handle_forwarded_tcpip_channel_open() function (Phase 13.3: Local port forwarding)
- Integrate security validation in direct-tcpip channel open
- Modify server.rs to pass security_config to handle_channel_open
- Add 128 lines of new channel handling functions
- All compilation tests passed successfully

Phase 13.1-13.3 completed: Enterprise security + Global request + Channel support

markbase-core/src/ssh_server/server.rs

@@ -403,7 +403,12 @@ fn handle_ssh_service_loop(
             
             Some(&pt) if pt == PacketType::SSH_MSG_CHANNEL_OPEN as u8 => {
                 info!("Received SSH_MSG_CHANNEL_OPEN");
-                let response = channel_manager.handle_channel_open(&packet)?;
+                
+                // Phase 13.3: 获取security_config并传递给handle_channel_open
+                let security = security_config.lock().unwrap();
+                let response = channel_manager.handle_channel_open(&packet, Some(&security))?;
+                drop(security);  // 释放锁
+                
                 let encrypted_response = EncryptedPacket::new(&response.payload, encryption_ctx, true)?;
                 encrypted_response.write(stream)?;
                 info!("Sent SSH_MSG_CHANNEL_OPEN_CONFIRMATION");