unlimited-concurrency.go

package main

import (
    "flag"
    "net"
    "os"
)

func main() {
    var addr string
    flag.StringVar(&addr, "addr", ":1202", "listen addr")
    flag.Parse()

    l, err := net.Listen("tcp", addr)
    if err != nil {
        os.Exit(1)
    }
    defer l.Close()

    for {
        conn, err := l.Accept()
        if err != nil {
            os.Exit(1)
        }
        go func(conn net.Conn) {
            buf := make([]byte, 1024)
            for {
                len, err := conn.Read(buf)
                if err != nil {
                    conn.Close()
                    return
                }
                conn.Write(append([]byte(addr+" "), buf[:len]...))
            }
        }(conn)
    }
}