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/channel.rs

@@ -88,6 +88,134 @@ impl ChannelManager {
         }
     }
     
+
+    /// 处理session channel open（Phase 6）
+    fn handle_session_channel_open(&mut self, sender_channel: u32, initial_window_size: u32, maximum_packet_size: u32) -> Result<SshPacket> {
+        info!("Processing session channel open");
+        
+        let server_channel = self.next_channel_id;
+        self.next_channel_id += 1;
+        
+        let channel = Channel {
+            server_channel,
+            sender_channel,
+            channel_type: "session".to_string(),
+            window_size: initial_window_size,
+            maximum_packet_size,
+            state: ChannelState::Open,
+            output_buffer: None,
+            sftp_handler: None,
+            scp_handler: None,
+            rsync_handler: None,
+            direct_tcpip: None,
+            forwarded_tcpip: None,
+        };
+        
+        self.channels.insert(server_channel, channel);
+        
+        info!("Session channel created: server_channel={}, sender_channel={}", server_channel, sender_channel);
+        
+        self.build_channel_open_confirmation(server_channel, sender_channel, initial_window_size, maximum_packet_size)
+    }
+    
+    /// 处理direct-tcpip channel open（Phase 13.3: Remote port forwarding）
+    fn handle_direct_tcpip_channel_open(
+        &mut self, 
+        packet: &SshPacket,
+        sender_channel: u32,
+        initial_window_size: u32,
+        maximum_packet_size: u32,
+        security_config: Option<&SshSecurityConfig>,
+    ) -> Result<SshPacket> {
+        info!("Processing direct-tcpip channel open");
+        
+        // 解析direct-tcpip参数
+        let mut port_forward_manager = PortForwardManager::new();
+        let direct_tcpip = port_forward_manager.handle_direct_tcpip_channel(&packet.payload)?;
+        
+        // Phase 13.3: 安全配置验证
+        if let Some(security) = security_config {
+            if let Err(e) = security.validate_direct_tcpip_channel(&direct_tcpip.host_to_connect, direct_tcpip.port_to_connect) {
+                warn!("direct-tcpip security validation failed: {}", e);
+                return self.build_channel_open_failure(
+                    sender_channel,
+                    2,  // SSH_OPEN_CONNECT_FAILED
+                    "Security validation failed",
+                    "en"
+                );
+            }
+            info!("direct-tcpip security validation passed");
+        }
+        
+        let server_channel = self.next_channel_id;
+        self.next_channel_id += 1;
+        
+        let channel = Channel {
+            server_channel,
+            sender_channel,
+            channel_type: "direct-tcpip".to_string(),
+            window_size: initial_window_size,
+            maximum_packet_size,
+            state: ChannelState::Open,
+            output_buffer: None,
+            sftp_handler: None,
+            scp_handler: None,
+            rsync_handler: None,
+            direct_tcpip: Some(direct_tcpip),
+            forwarded_tcpip: None,
+        };
+        
+        self.channels.insert(server_channel, channel);
+        
+        info!("direct-tcpip channel created: server_channel={}, host={}, port={}", 
+            server_channel, 
+            self.channels.get(&server_channel).unwrap().direct_tcpip.as_ref().unwrap().host_to_connect,
+            self.channels.get(&server_channel).unwrap().direct_tcpip.as_ref().unwrap().port_to_connect);
+        
+        self.build_channel_open_confirmation(server_channel, sender_channel, initial_window_size, maximum_packet_size)
+    }
+    
+    /// 处理forwarded-tcpip channel open（Phase 13.3: Local port forwarding）
+    fn handle_forwarded_tcpip_channel_open(
+        &mut self,
+        packet: &SshPacket,
+        sender_channel: u32,
+        initial_window_size: u32,
+        maximum_packet_size: u32,
+    ) -> Result<SshPacket> {
+        info!("Processing forwarded-tcpip channel open");
+        
+        // 解析forwarded-tcpip参数
+        let mut port_forward_manager = PortForwardManager::new();
+        let forwarded_tcpip = port_forward_manager.handle_forwarded_tcpip_channel(&packet.payload)?;
+        
+        let server_channel = self.next_channel_id;
+        self.next_channel_id += 1;
+        
+        let channel = Channel {
+            server_channel,
+            sender_channel,
+            channel_type: "forwarded-tcpip".to_string(),
+            window_size: initial_window_size,
+            maximum_packet_size,
+            state: ChannelState::Open,
+            output_buffer: None,
+            sftp_handler: None,
+            scp_handler: None,
+            rsync_handler: None,
+            direct_tcpip: None,
+            forwarded_tcpip: Some(forwarded_tcpip),
+        };
+        
+        self.channels.insert(server_channel, channel);
+        
+        info!("forwarded-tcpip channel created: server_channel={}, bind={}, originator={}", 
+            server_channel, 
+            self.channels.get(&server_channel).unwrap().forwarded_tcpip.as_ref().unwrap().bind_port,
+            self.channels.get(&server_channel).unwrap().forwarded_tcpip.as_ref().unwrap().originator_address);
+        
+        self.build_channel_open_confirmation(server_channel, sender_channel, initial_window_size, maximum_packet_size)
+    }
     /// 处理SSH_MSG_CHANNEL_REQUEST（参考OpenSSH channel.c: channel_request())
     pub fn handle_channel_request(&mut self, packet: &SshPacket) -> Result<Option<SshPacket>> {
         info!("Processing SSH_MSG_CHANNEL_REQUEST");