golang-tcp-dscp.go

package main
import (
    "net"
    "os"
    "syscall"
    "time"
)

func main() {
    strEcho := "Halo"
    servAddr := "localhost:6666"

    dialer := net.Dialer{
        Timeout: time.Second * 10,
    }
    dialer.Control = func(network, address string, c syscall.RawConn) error {
        var err error
        c.Control(func(fd uintptr) {
            err = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x80)
        })
        return err
    }

    conn, err := dialer.Dial("tcp", servAddr)
    if err != nil {
        println("Dial failed:", err.Error())
        os.Exit(1)
    }

    _, err = conn.Write([]byte(strEcho))
    if err != nil {
        println("Write to server failed:", err.Error())
        os.Exit(1)
    }

    println("write to server = ", strEcho)

    reply := make([]byte, 1024)

    _, err = conn.Read(reply)
    if err != nil {
        println("Write to server failed:", err.Error())
        os.Exit(1)
    }

    println("reply from server=", string(reply))

    conn.Close()
}