yanic/api/lib.go

package api

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"net/http"
	"strings"

	"github.com/julienschmidt/httprouter"
)

func jsonOutput(w http.ResponseWriter, r *http.Request, data interface{}) {
	js, err := json.Marshal(data)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	if origin := r.Header.Get("Origin"); origin != "" {
		w.Header().Set("Access-Control-Allow-Origin", origin)
	}
	w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
	w.Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization")
	w.Header().Set("Access-Control-Allow-Credentials", "true")
	w.Write(js)
}

// BasicAuth for API request
func BasicAuth(h httprouter.Handle, pass []byte) httprouter.Handle {
	return func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
		if origin := r.Header.Get("Origin"); origin != "" {
			w.Header().Set("Access-Control-Allow-Origin", origin)
		}
		w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
		w.Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization")
		w.Header().Set("Access-Control-Allow-Credentials", "true")

		const basicAuthPrefix string = "Basic "

		// Get the Basic Authentication credentials
		auth := r.Header.Get("Authorization")
		if strings.HasPrefix(auth, basicAuthPrefix) {
			// Check credentials
			payload, err := base64.StdEncoding.DecodeString(auth[len(basicAuthPrefix):])
			if err == nil {
				pair := bytes.SplitN(payload, []byte(":"), 2)
				if len(pair) == 2 &&
					bytes.Equal(pair[1], pass) {

					// Delegate request to the given handle
					h(w, r, ps)
					return
				}
			}
		}

		// Request Basic Authentication otherwise
		w.Header().Set("WWW-Authenticate", "Basic realm=Restricted")
		http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
	}
}