Golang web server example

auth.go

package main

import (
    "encoding/base64"
    "net/http"
    "strings"
)

type handler func(w http.ResponseWriter, r *http.Request)

func BasicAuth(pass handler) handler {

    return func(w http.ResponseWriter, r *http.Request) {

        auth := strings.SplitN(r.Header["Authorization"][0], " ", 2)

        if len(auth) != 2 || auth[0] != "Basic" {
            http.Error(w, "bad syntax", http.StatusBadRequest)
            return
        }

        payload, _ := base64.StdEncoding.DecodeString(auth[1])
        pair := strings.SplitN(string(payload), ":", 2)

        if len(pair) != 2 || !Validate(pair[0], pair[1]) {
            http.Error(w, "authorization failed", http.StatusUnauthorized)
            return
        }

        pass(w, r)
    }
}

func Validate(username, password string) bool {
    if username == "username" && password == "password" {
        return true
    }
    return false
}

main.go

package main

import (
    "log"
    "net/http"
)

func main() {

    // public views
    http.HandleFunc("/", HandleIndex)

    // private views
    http.HandleFunc("/post", PostOnly(BasicAuth(HandlePost)))
    http.HandleFunc("/json", GetOnly(BasicAuth(HandleJSON)))

    log.Fatal(http.ListenAndServe(":8080", nil))
}

routes.go

package main

import (
    "encoding/json"
    "io"
    "log"
    "net/http"
)

func HandleIndex(w http.ResponseWriter, r *http.Request) {
    io.WriteString(w, "hello, world\n")
}

func HandlePost(w http.ResponseWriter, r *http.Request) {
    r.ParseForm()
    log.Println(r.PostForm)
    io.WriteString(w, "post\n")
}

type Result struct {
    FirstName string `json:"first"`
    LastName  string `json:"last"`
}

func HandleJSON(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    result, _ := json.Marshal(Result{"tee", "dub"})
    io.WriteString(w, string(result))
}

tests.sh

curl http://0.0.0.0:8080
curl -u username:password -d "param1=value1&param2=value2" http://0.0.0.0:8080/post  
curl -u username:password http://0.0.0.0:8080/json 

wrappers.go

package main

import (
    "net/http"
)

func GetOnly(h handler) handler {

    return func(w http.ResponseWriter, r *http.Request) {
        if r.Method == "GET" {
            h(w, r)
            return
        }
        http.Error(w, "get only", http.StatusMethodNotAllowed)
    }
}

func PostOnly(h handler) handler {

    return func(w http.ResponseWriter, r *http.Request) {
        if r.Method == "POST" {
            h(w, r)
            return
        }
        http.Error(w, "post only", http.StatusMethodNotAllowed)
    }
}

Why to reinvent the wheel?

type handler func(w http.ResponseWriter, r *http.Request)

 func BasicAuth(pass handler) handler {

    return func(w http.ResponseWriter, r *http.Request) {

        username, password, _ := r.BasicAuth()

        if username != "username" || password != "password" {
            http.Error(w, "authorization failed", http.StatusUnauthorized)
            return
        }
        pass(w, r)
    }
 }

would be sufficient.