feat(socket-handler): implement direct socket passing for DNS and email services

- Add socket-handler mode eliminating internal port binding for improved performance
- Add `dnsDomain` config option for automatic DNS-over-HTTPS (DoH) setup
- Add `useSocketHandler` flag to email config for direct socket processing
- Update SmartProxy route generation to support socket-handler actions
- Integrate smartdns with manual HTTPS mode for DoH without port binding
- Add automatic route creation for DNS paths when dnsDomain is configured
- Update documentation with socket-handler configuration and benefits
- Improve resource efficiency by eliminating internal port forwarding

ts/mail/routing/classes.unified.email.server.ts

@@ -49,6 +49,7 @@ export interface IUnifiedEmailServerOptions {
   domains: string[];  // Domains to handle email for
   banner?: string;
   debug?: boolean;
+  useSocketHandler?: boolean;  // Use socket-handler mode instead of port listening
   
   // Authentication options
   auth?: {
@@ -336,6 +337,13 @@ export class UnifiedEmailServer extends EventEmitter {
         logger.log('info', 'Automatic DKIM configuration completed');
       }
       
+      // Skip server creation in socket-handler mode
+      if (this.options.useSocketHandler) {
+        logger.log('info', 'UnifiedEmailServer started in socket-handler mode (no port listening)');
+        this.emit('started');
+        return;
+      }
+      
       // Ensure we have the necessary TLS options
       const hasTlsConfig = this.options.tls?.keyPath && this.options.tls?.certPath;
       
@@ -446,6 +454,54 @@ export class UnifiedEmailServer extends EventEmitter {
     }
   }
   
+  /**
+   * Handle a socket from smartproxy in socket-handler mode
+   * @param socket The socket to handle
+   * @param port The port this connection is for (25, 587, 465)
+   */
+  public async handleSocket(socket: plugins.net.Socket | plugins.tls.TLSSocket, port: number): Promise<void> {
+    if (!this.options.useSocketHandler) {
+      logger.log('error', 'handleSocket called but useSocketHandler is not enabled');
+      socket.destroy();
+      return;
+    }
+    
+    logger.log('info', `Handling socket for port ${port}`);
+    
+    // Create a temporary SMTP server instance for this connection
+    // We need a full server instance because the SMTP protocol handler needs all components
+    const smtpServerOptions = {
+      port,
+      hostname: this.options.hostname,
+      key: this.options.tls?.keyPath ? plugins.fs.readFileSync(this.options.tls.keyPath, 'utf8') : undefined,
+      cert: this.options.tls?.certPath ? plugins.fs.readFileSync(this.options.tls.certPath, 'utf8') : undefined
+    };
+    
+    // Create the SMTP server instance
+    const smtpServer = createSmtpServer(this, smtpServerOptions);
+    
+    // Get the connection manager from the server
+    const connectionManager = (smtpServer as any).connectionManager;
+    
+    if (!connectionManager) {
+      logger.log('error', 'Could not get connection manager from SMTP server');
+      socket.destroy();
+      return;
+    }
+    
+    // Determine if this is a secure connection
+    // Port 465 uses implicit TLS, so the socket is already secure
+    const isSecure = port === 465 || socket instanceof plugins.tls.TLSSocket;
+    
+    // Pass the socket to the connection manager
+    try {
+      await connectionManager.handleConnection(socket, isSecure);
+    } catch (error) {
+      logger.log('error', `Error handling socket connection: ${error.message}`);
+      socket.destroy();
+    }
+  }
+  
   /**
    * Stop the unified email server
    */