Creating a TCP client in golang

Question

Hi i'm attempted to learn some socket programming in golang, I'm following along with this tutorial

http://synflood.at/tmp/golang-slides/mrmcd2012.html#1

Here is the final result of the tutorial on one page. https://github.com/akrennmair/telnet-chat/blob/master/03_chat/chat.go

I'm confused on how to write the client side of this program, I create a connection and dial into the same port/ip as the server is running on but from there I don't know. I have read() and write() functions for the newly created connection but no idea where to delimit the read or anything. Considering the text input is handeled in the server I imagine I'd only need to do a read of some kind?

package main

import (
    "bufio"
    "fmt"
    "net"
    "os"
)

func main() {
    conn, err := net.Dial("tcp", "127.0.0.1:6000")
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }

    for {
        fmt.Println(bufio.NewReader(conn).ReadString([]byte("\n")))
    }

}

Answer 1

bufio.NewReadershould be used only once, in your case, just before the for. For example connbuf := bufio.NewReader(conn). Then you can use ReadString on connbuf, that returns the string and maybe an error. For example:

connbuf := bufio.NewReader(conn)
for{
    str, err := connbuf.ReadString('\n')
    if err != nil {
        break
    }

    if len(str) > 0 {
        fmt.Println(str)
    }
}

I'm checking lenand err because ReadString may return data and an error (connection error, connection reset, etc.) so you need to check both.

Answer 2

Here is a simple solution if you want to read all received data.

    connbuf := bufio.NewReader(c.m_socket)
    // Read the first byte and set the underlying buffer
    b, _ := connbuf.ReadByte() 
    if connbuf.Buffered() > 0 {
        var msgData []byte
        msgData = append(msgData, b)
        for connbuf.Buffered() > 0 {
            // read byte by byte until the buffered data is not empty
            b, err := connbuf.ReadByte()
            if err == nil {
                msgData = append(msgData, b)
            } else {
                log.Println("-------> unreadable caracter...", b)
            }
        }
        // msgData now contain the buffered data...
    }