Question

How I can implement a server in Go, which sends each incomming line to stdout ?

package main

import (
    "io"
    "log"
    "net"
)

func main() {
    srv, err := net.Listen("tcp", ":2000")
    for {
        conn, err := srv.Accept()
        go func(c net.Conn) {

            //How to split here by lines ?

            c.Close()
        }(conn)
    }
}

After runing the server with

./server

And running telnet

telnet localhost 2000
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
test 123
foobar

I want to see on stdout where I started the server:

test 123
foobar

I know this code lacks error handling, but this is only for clearity to show what I’m trying to do.

Answer 1

Since a net.Conn is an io.Reader, you can wrap it in a bufio.Reader and use the ReadString method on that type. Your function would become

func(c net.Conn) {
    f := bufio.NewReader(c)
    for {
        ln, err := f.ReadString('\n')
        if err == io.EOF {
            break
        } else if err != nil {
            panic(err)
        }
        fmt.Print(ln)
    }
    c.Close()
}

(I’m not sure if stdout is synchronized in Go; it might be cleaner to send the lines on a shared channel that is looped over in a separate goroutine.)