How to do it…

In this recipe, we are going to update the HTTP server we created in the previous recipe by adding a BasicAuth function and modifying the HandleFunc to call it. Perform the following steps:

1. Create http-server-basic-authentication.go and copy the following content:

package main
import 
(
  "crypto/subtle"
  "fmt"
  "log"
  "net/http"
)
const 
(
  CONN_HOST = "localhost"
  CONN_PORT = "8080"
  ADMIN_USER = "admin"
  ADMIN_PASSWORD = "admin"
)
func helloWorld(w http.ResponseWriter, r *http.Request) 
{
  fmt.Fprintf(w, "Hello World!")
}
func BasicAuth(handler http.HandlerFunc, realm string) http.HandlerFunc {
  return func(w http.ResponseWriter, r *http.Request) 
  {
    user, pass, ok := r.BasicAuth()
    if !ok || subtle.ConstantTimeCompare([]byte(user),
    []byte(ADMIN_USER)) != 1||subtle.ConstantTimeCompare([]byte(pass), 
    []byte(ADMIN_PASSWORD)) != 1 
    {
      w.Header().Set("WWW-Authenticate", `Basic realm="`+realm+`"`)
      w.WriteHeader(401)
      w.Write([]byte("You are Unauthorized to access the
      application.\n"))
      return
    }
    handler(w, r)
  }
}
func main() 
{
  http.HandleFunc("/", BasicAuth(helloWorld, "Please enter your
  username and password"))
  err := http.ListenAndServe(CONN_HOST+":"+CONN_PORT, nil)
  if err != nil 
  {
    log.Fatal("error starting http server : ", err)
    return
  }
}

2. Run the program with the following command:

$ go run http-server-basic-authentication.go