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- package tcpprox
- import (
- "io"
- "log"
- "net"
- "sync"
- "time"
- )
- func isValidIP(ip string) bool {
- parsedIP := net.ParseIP(ip)
- return parsedIP != nil
- }
- /*
- Connection Copy
- Copy between two connections, and accumlate the copied bytes in the
- accumulator number
- */
- func connCopy(conn1 net.Conn, conn2 net.Conn, wg *sync.WaitGroup, accumulator *int64) {
- io.Copy(conn1, conn2)
- conn1.Close()
- log.Println("[←]", "close the connect at local:["+conn1.LocalAddr().String()+"] and remote:["+conn1.RemoteAddr().String()+"]")
- //conn2.Close()
- //log.Println("[←]", "close the connect at local:["+conn2.LocalAddr().String()+"] and remote:["+conn2.RemoteAddr().String()+"]")
- wg.Done()
- }
- func forward(conn1 net.Conn, conn2 net.Conn) {
- 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
- // wait tow goroutines
- wg.Add(2)
- go connCopy(conn1, conn2, &wg)
- go connCopy(conn2, conn1, &wg)
- //blocking when the wg is locked
- wg.Wait()
- }
- func accept(listener net.Listener) net.Conn {
- conn, err := listener.Accept()
- if err != nil {
- log.Println("[x]", "accept connect ["+conn.RemoteAddr().String()+"] faild.", err.Error())
- return nil
- }
- log.Println("[√]", "accept a new client. remote address:["+conn.RemoteAddr().String()+"], local address:["+conn.LocalAddr().String()+"]")
- return conn
- }
- func start_server(address string) net.Listener {
- log.Println("[+]", "try to start server on:["+address+"]")
- server, err := net.Listen("tcp", address)
- if err != nil {
- log.Fatalln("[x]", "listen address ["+address+"] faild.")
- }
- log.Println("[√]", "start listen at address:["+address+"]")
- return server
- }
- func port2port(port1 string, port2 string) {
- listen1 := start_server("0.0.0.0:" + port1)
- listen2 := start_server("0.0.0.0:" + port2)
- log.Println("[√]", "listen port:", port1, "and", port2, "success. waiting for client...")
- for {
- conn1 := accept(listen1)
- conn2 := accept(listen2)
- if conn1 == nil || conn2 == nil {
- log.Println("[x]", "accept client faild. retry in ", timeout, " seconds. ")
- time.Sleep(timeout * time.Second)
- continue
- }
- forward(conn1, conn2)
- }
- }
- func port2host(allowPort string, targetAddress string) {
- server := start_server("0.0.0.0:" + allowPort)
- for {
- conn := accept(server)
- if conn == nil {
- continue
- }
- //println(targetAddress)
- go func(targetAddress string) {
- log.Println("[+]", "start connect host:["+targetAddress+"]")
- target, err := net.Dial("tcp", targetAddress)
- if err != nil {
- // temporarily unavailable, don't use fatal.
- log.Println("[x]", "connect target address ["+targetAddress+"] faild. retry in ", timeout, "seconds. ")
- conn.Close()
- log.Println("[←]", "close the connect at local:["+conn.LocalAddr().String()+"] and remote:["+conn.RemoteAddr().String()+"]")
- time.Sleep(timeout * time.Second)
- return
- }
- log.Println("[→]", "connect target address ["+targetAddress+"] success.")
- forward(target, conn)
- }(targetAddress)
- }
- }
- func host2host(address1, address2 string) {
- for {
- log.Println("[+]", "try to connect host:["+address1+"] and ["+address2+"]")
- var host1, host2 net.Conn
- var err error
- for {
- host1, err = net.Dial("tcp", address1)
- if err == nil {
- log.Println("[→]", "connect ["+address1+"] success.")
- break
- } else {
- log.Println("[x]", "connect target address ["+address1+"] faild. retry in ", timeout, " seconds. ")
- time.Sleep(timeout * time.Second)
- }
- }
- for {
- host2, err = net.Dial("tcp", address2)
- if err == nil {
- log.Println("[→]", "connect ["+address2+"] success.")
- break
- } else {
- log.Println("[x]", "connect target address ["+address2+"] faild. retry in ", timeout, " seconds. ")
- time.Sleep(timeout * time.Second)
- }
- }
- forward(host1, host2)
- }
- }
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