fix three possible half-opened connections

client/main.go

@@ -50,7 +50,11 @@ func handleTCPConnection(c net.Conn) {
 	logger.Debugf("addressType: %d\n", addressType)
 	logger.Debugf("port: %d\n", port)
 
-	c.Write(reqAnswer)
+	_, err = c.Write(reqAnswer)
+	if err != nil {
+		logger.Warningf("write req answer failed: %s", err)
+		return
+	}
 
 	proxyAgent, err := tunnel.NewClient(lc.Tunnel, lc.Server, lc.ServerPort, lc.MasterKey, lc.EncryptMethod, lc.Password, logger)
 	if err != nil {

client/socks5.go

@@ -29,8 +29,8 @@ func handShake(c net.Conn) error {
 		return fmt.Errorf("Protocol mismatch: %d", protoVersion)
 	}
 
-	c.Write(handShakeAnswer)
-	return nil
+	_, err = c.Write(handShakeAnswer)
+	return err
 }
 
 // commandCode, addressType, address, port, err
@@ -85,8 +85,8 @@ func parseReq(c net.Conn) (byte, byte, []byte, uint16, error) {
 	}
 
 	var port uint16
-	binary.Read(r, binary.BigEndian, &port)
+	err = binary.Read(r, binary.BigEndian, &port)
 
 	// commandCode, addressType, address, port, err
-	return commandCode, addressType, address.Bytes(), port, nil
+	return commandCode, addressType, address.Bytes(), port, err
 }