Added Proxy Protocol V1 function.

- Added useProxyProtocol in ProxyRelayConfig
- Added writeProxyProtocolHeaderV1 function

src/mod/streamproxy/tcpprox.go

@@ -2,6 +2,7 @@ package streamproxy
 
 import (
 	"errors"
+	"fmt"
 	"io"
 	"log"
 	"net"
@@ -43,6 +44,23 @@ func connCopy(conn1 net.Conn, conn2 net.Conn, wg *sync.WaitGroup, accumulator *a
 	wg.Done()
 }
 
+func writeProxyProtocolHeaderV1(dst net.Conn, src net.Conn) error {
+	clientAddr, ok1 := src.RemoteAddr().(*net.TCPAddr)
+	proxyAddr, ok2 := src.LocalAddr().(*net.TCPAddr)
+	if !ok1 || !ok2 {
+		return errors.New("invalid TCP address for proxy protocol")
+	}
+
+	header := fmt.Sprintf("PROXY TCP4 %s %s %d %d\r\n",
+		clientAddr.IP.String(),
+		proxyAddr.IP.String(),
+		clientAddr.Port,
+		proxyAddr.Port)
+
+	_, err := dst.Write([]byte(header))
+	return err
+}
+
 func forward(conn1 net.Conn, conn2 net.Conn, aTob *atomic.Int64, bToa *atomic.Int64) {
 	log.Printf("[+] start transmit. [%s],[%s] <-> [%s],[%s] \n", conn1.LocalAddr().String(), conn1.RemoteAddr().String(), conn2.LocalAddr().String(), conn2.RemoteAddr().String())
 	var wg sync.WaitGroup
@@ -127,7 +145,7 @@ func (c *ProxyRelayConfig) Port2host(allowPort string, targetAddress string, sto
 			//Connection error. Retry
 			continue
 		}
-
+		log.Println("[+]", "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA")
 		go func(targetAddress string) {
 			log.Println("[+]", "start connect host:["+targetAddress+"]")
 			target, err := net.Dial("tcp", targetAddress)
@@ -140,6 +158,20 @@ func (c *ProxyRelayConfig) Port2host(allowPort string, targetAddress string, sto
 				return
 			}
 			log.Println("[→]", "connect target address ["+targetAddress+"] success.")
+
+			if c.UseProxyProtocol {
+				log.Println("[+]", "write proxy protocol header to target address ["+targetAddress+"]")
+				err = writeProxyProtocolHeaderV1(target, conn)
+				if err != nil {
+					log.Println("[x]", "Write proxy protocol header faild: ", err)
+					target.Close()
+					conn.Close()
+					log.Println("[←]", "close the connect at local:["+conn.LocalAddr().String()+"] and remote:["+conn.RemoteAddr().String()+"]")
+					time.Sleep(time.Duration(c.Timeout) * time.Second)
+					return
+				}
+			}
+
 			forward(target, conn, &c.aTobAccumulatedByteTransfer, &c.bToaAccumulatedByteTransfer)
 		}(targetAddress)
 	}