Golang : Issue HTTP commands to server and port example

Problem :

You want to issue or write HTTP command to a connection created by net.DialTCP() function. How to do that?

Solution :

The net.Conn type connection returned by net.DialTCP() function has Write method. Use the Write method to issue HTTP command.

For example :

 package main

 import (
 "fmt"
 "io/ioutil"
 "net"
 "os"
 )

 func main() {
 if len(os.Args) != 2 {
 fmt.Printf("Usage: %s hostname:port_number \n", os.Args[0])
 os.Exit(1)
 }

 serviceAndPort := os.Args[1]

 fmt.Println("Service : ", serviceAndPort)

 tcpAddr, err := net.ResolveTCPAddr("tcp4", serviceAndPort)

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 conn, err := net.DialTCP("tcp", nil, tcpAddr)

 defer conn.Close()

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 // issue the HTTP command

 nBytes, err := conn.Write([]byte("HEAD / HTTP/1.0\r\n\r\n"))

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 fmt.Printf("Written %v bytes\n", nBytes)



 result, err := ioutil.ReadAll(conn)

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 fmt.Println(string(result))

 }

References :

http://golang.org/pkg/net/#Conn

http://papa.det.uvigo.es/~theiere/cursos/Curso_WWW/codes.html

https://socketloop.com/tutorials/golang-get-curl-i-or-head-data-from-url-example