first commit

.gitignore

@@ -6,6 +6,8 @@
 *.so
 *.dylib
 
+simple-tcp-proxy
+
 # Test binary, build with `go test -c`
 *.test
 

simple-tcp-proxy.go

@@ -0,0 +1,124 @@
+package main
+ 
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net"
+	"os"
+	"strings"
+	"encoding/json"
+)
+
+type TcpListen struct {
+	Listen string `json:"listen"`
+	Backend string `json:"backend"`
+}
+
+type TcpListenConfig struct {
+	TcpListens []TcpListen `json:"tcpListens"`
+}
+
+// {
+//   "tcpListens": [
+//       "listen": ":8080",
+//       "backend": "11.22.33.44:8080"
+//   ]
+// }
+// https://blog.csdn.net/fyxichen/article/details/51505542 
+func main() {
+
+	tcpListenConfig, err := readConfigFile()
+
+	if err != nil {
+		fmt.Printf("Error in load config file: %v\n", err)
+		return
+	}
+
+	if len(tcpListenConfig.TcpListens) == 0 {
+		fmt.Println("Not find any mapping in config")
+		return
+	}
+
+	for _, tcpListen := range tcpListenConfig.TcpListens {
+		go server(tcpListen)
+	}
+	ExitChan := make(chan bool, 1)
+	<-ExitChan
+}
+
+func server(tcpListen TcpListen) {
+	lis, err := net.Listen("tcp", tcpListen.Listen)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer lis.Close()
+	fmt.Printf("Listen TCP at: %v  --> %v\n", tcpListen.Listen, tcpListen.Backend)
+	for {
+		conn, err := lis.Accept()
+		if err != nil {
+			fmt.Printf("Listen error: %v\n", err)
+			continue
+		}
+		fmt.Printf("TCP connection from %v, local: %v\n", conn.RemoteAddr(), conn.LocalAddr())
+		go handle(tcpListen, conn)
+	}
+}
+
+func handle(tcpListen TcpListen, sconn net.Conn) {
+	defer sconn.Close()
+	ip := tcpListen.Backend
+	dconn, err := net.Dial("tcp", ip)
+	if err != nil {
+		fmt.Printf("Connect to %v failed:%v\n", ip, err)
+		return
+	}
+	ExitChan := make(chan bool, 1)
+	go func(sconn net.Conn, dconn net.Conn, Exit chan bool) {
+		_, err := io.Copy(dconn, sconn)
+		if err != nil {
+			errStr := fmt.Sprintf("%v", err)
+			if strings.Contains(errStr, "use of closed network connection") {
+				fmt.Printf("Connection closed: %v\n", ip)
+			} else {
+				fmt.Printf("Send data to %v failed:%v\n", ip, err)
+			}
+		}
+		ExitChan <- true
+	}(sconn, dconn, ExitChan)
+	go func(sconn net.Conn, dconn net.Conn, Exit chan bool) {
+		_, err := io.Copy(sconn, dconn)
+		if err != nil {
+			errStr := fmt.Sprintf("%v", err)
+			if strings.Contains(errStr, "use of closed network connection") {
+				fmt.Printf("Connection closed: %v\n", ip)
+			} else {
+				fmt.Printf("Receive data from %v failed:%v\n", ip, err)
+			}
+		}
+		ExitChan <- true
+	}(sconn, dconn, ExitChan)
+	<-ExitChan
+	dconn.Close()
+}
+
+func readConfigFile() (*TcpListenConfig, error) {
+	configFile, err := os.Open("tcp_listen_config.json")
+	if err != nil {
+		return nil, err
+	}
+	defer configFile.Close()
+
+	configFileBytes, err := ioutil.ReadAll(configFile)
+	if err != nil {
+		return nil, err
+	}
+	var tcpListenConfig TcpListenConfig 
+	err = json.Unmarshal(configFileBytes, &tcpListenConfig)
+	if err != nil {
+		return nil, err
+	}
+ 	
+	return &tcpListenConfig, nil
+}

tcp_listen_config.json

@@ -0,0 +1,8 @@
+{
+ "tcpListens": [
+   {
+     "listen": ":8443",
+     "backend": "101.132.122.240:443"
+   }
+ ]
+}