Golang : Simple client server example

This a quick tutorial on creating a bare bone client-server program with Golang. We will start with the server part first and then followed by client part. You can use this as a foundation to create your own client-server program.

server.go

 package main

 import (
  "fmt"
  "log"
  "net"
 )

 func handleConnection(c net.Conn) {

  log.Printf("Client %v connected.", c.RemoteAddr())

  // stuff to do... like read data from client, process it, write back to client
  // see what you can do with (c net.Conn) at
  // http://golang.org/pkg/net/#Conn

  // buffer := make([]byte, 4096)

  //for {
  //  n, err := c.Read(buffer)
  //  if err != nil || n == 0 {
  // c.Close()
  // break
  //  }
  //  n, err = c.Write(buffer[0:n])
  //  if err != nil {
  // c.Close()
  // break
  //  }
  // }
  log.Printf("Connection from %v closed.", c.RemoteAddr())
 }

 func main() {
  ln, err := net.Listen("tcp", ":6000")
  if err != nil {
 log.Fatal(err)
  }

  fmt.Println("Server up and listening on port 6000")

  for {
 conn, err := ln.Accept()
 if err != nil {
 log.Println(err)
 continue
 }
 go handleConnection(conn)
  }
 }

compile the server.go and run it as a background process :

./server &

then run the client on a separate machine(if possible) and connect to the server

client.go

 package main

 import (
 "fmt"
 "net"
 )

 func main() {
 hostName := "example.com" // change this
 portNum := "6000"

 conn, err := net.Dial("tcp", hostName+":"+portNum)

 if err != nil {
 fmt.Println(err)
 return
 }

 fmt.Printf("Connection established between %s and localhost.\n", hostName)
 fmt.Printf("Remote Address : %s \n", conn.RemoteAddr().String())
 fmt.Printf("Local Address : %s \n", conn.LocalAddr().String())

 }

Sample output :

For client

./client-dial

Connection established between socketloop.com and localhost.

Remote Address : 162.243.5.230:6000

Local Address : 192.168.1.65:49774

For server

./server

Server up and listening on port 6000

2015/05/09 08:55:55 Client 14.192.213.197:8017 connected.

2015/05/09 08:55:55 Connection from 14.192.213.197:8017 closed.

This should be the basis of creating client-server programs with Golang. Hope you find this tutorial useful.

Check out this example as well on establishing secure(SSL/TLS) connection between client-server :

https://www.socketloop.com/references/golang-crypto-tls-listen-and-newlistener-functions-example