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@jkuri
Forked from vmihailenco/proxy.go
Created Nov 16, 2017
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Simple TCP proxy in Golang
package main
import (
"bytes"
"encoding/hex"
"flag"
"fmt"
"io"
"log"
"net"
)
var localAddr *string = flag.String("l", "localhost:9999", "local address")
var remoteAddr *string = flag.String("r", "localhost:80", "remote address")
func proxyConn(conn *net.TCPConn) {
rAddr, err := net.ResolveTCPAddr("tcp", *remoteAddr)
if err != nil {
panic(err)
}
rConn, err := net.DialTCP("tcp", nil, rAddr)
if err != nil {
panic(err)
}
defer rConn.Close()
buf := &bytes.Buffer{}
for {
data := make([]byte, 256)
n, err := conn.Read(data)
if err != nil {
panic(err)
}
buf.Write(data[:n])
if data[0] == 13 && data[1] == 10 {
break
}
}
if _, err := rConn.Write(buf.Bytes()); err != nil {
panic(err)
}
log.Printf("sent:\n%v", hex.Dump(buf.Bytes()))
data := make([]byte, 1024)
n, err := rConn.Read(data)
if err != nil {
if err != io.EOF {
panic(err)
} else {
log.Printf("received err: %v", err)
}
}
log.Printf("received:\n%v", hex.Dump(data[:n]))
}
func handleConn(in <-chan *net.TCPConn, out chan<- *net.TCPConn) {
for conn := range in {
proxyConn(conn)
out <- conn
}
}
func closeConn(in <-chan *net.TCPConn) {
for conn := range in {
conn.Close()
}
}
func main() {
flag.Parse()
fmt.Printf("Listening: %v\nProxying: %v\n\n", *localAddr, *remoteAddr)
addr, err := net.ResolveTCPAddr("tcp", *localAddr)
if err != nil {
panic(err)
}
listener, err := net.ListenTCP("tcp", addr)
if err != nil {
panic(err)
}
pending, complete := make(chan *net.TCPConn), make(chan *net.TCPConn)
for i := 0; i < 5; i++ {
go handleConn(pending, complete)
}
go closeConn(complete)
for {
conn, err := listener.AcceptTCP()
if err != nil {
panic(err)
}
pending <- conn
}
}
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