go-examples/photoblog/admin/admin.go
2017-07-30 10:01:23 +02:00

152 lines
4.0 KiB
Go

package admin
import (
"crypto/hmac"
"crypto/sha256"
"errors"
"fmt"
"html/template"
"io/ioutil"
"log"
"net/http"
"os"
"path/filepath"
"time"
"github.com/gorilla/sessions"
)
const (
USER = "username"
PWD = "password"
SESS_USER = "username"
SESSION = "photoblog.session"
)
// Application
type AuthCookie struct {
Templates *template.Template
Store *sessions.CookieStore
DataDir *os.File
PasswordSecret string
}
// Constructor AuthCookie
func NewAuthCookie(tpl *template.Template, sessionSecret, passwordSecret string, data *os.File) *AuthCookie {
app := &AuthCookie{
Templates: tpl,
Store: sessions.NewCookieStore([]byte(sessionSecret)),
DataDir: data,
PasswordSecret: passwordSecret,
}
app.Store.Options = &sessions.Options{
Secure: true,
HttpOnly: true,
MaxAge: int((24 * time.Hour) / time.Second),
}
return app
}
// Verify Username
func (app *AuthCookie) VerifyUsername(username string) error {
if username == "" {
return errors.New("Empty username")
}
return nil
}
// Verify password for user, check with file
func (app *AuthCookie) VerifyPassword(username, password string, res http.ResponseWriter, req *http.Request) error {
if password == "" {
return errors.New("Empty password")
}
if username == "" {
return nil
}
// open password file
passfile, err := os.Open(filepath.Join(app.DataDir.Name(), username, ".password"))
if err != nil {
log.Println("Cannot open password file", err)
return errors.New("Authentification failed")
}
defer passfile.Close()
// read password file
expected, err := ioutil.ReadAll(passfile)
if err != nil {
log.Println("Cannot read password file", err)
return errors.New("Authentification failed")
}
// hash password and compare
expectedStr := string(expected)
var expectedMAC []byte
fmt.Sscanf(expectedStr, "%x", &expectedMAC)
mac := hmac.New(sha256.New, []byte(app.PasswordSecret))
mac.Write([]byte(password))
passwordMAC := mac.Sum(nil)
if !hmac.Equal(passwordMAC, expectedMAC) {
log.Printf("Unmatched password for %s: %x - %x\n", username, passwordMAC, expectedMAC)
return errors.New("Authentification failed")
}
log.Printf("Authentification successful (" + username + ")")
return nil
}
// Save username in session
func (app *AuthCookie) SaveUsername(username string, res http.ResponseWriter, req *http.Request) {
session := app.CurrentSession(res, req)
session.Values[SESS_USER] = username
session.Save(req, res)
}
// Test if a user is logged in
func (app *AuthCookie) IsLoggedIn(res http.ResponseWriter, req *http.Request) bool {
session := app.CurrentSession(res, req)
return session != nil && session.Values[SESS_USER] != ""
}
// Current username (from session cookie)
func (app *AuthCookie) Username(res http.ResponseWriter, req *http.Request) string {
session := app.CurrentSession(res, req)
if session == nil {
return ""
}
val, _ := session.Values[SESS_USER].(string)
return val
}
// Current session
func (app *AuthCookie) CurrentSession(res http.ResponseWriter, req *http.Request) *sessions.Session {
session, _ := app.Store.Get(req, SESSION)
return session
}
// Redirect to home page
func (app *AuthCookie) RedirectHome(res http.ResponseWriter, req *http.Request) {
http.Redirect(res, req, "/", http.StatusSeeOther)
}
// ROUTES //
// login: form
func (app *AuthCookie) LoginPage(res http.ResponseWriter, req *http.Request) {
formErr := make(map[string]error)
if req.Method == http.MethodPost {
username := req.FormValue(USER)
formErr[USER] = app.VerifyUsername(username)
formErr[PWD] = app.VerifyPassword(username, req.FormValue(PWD), res, req)
if formErr[USER] == nil && formErr[PWD] == nil {
app.SaveUsername(username, res, req)
app.RedirectHome(res, req)
return
}
}
app.Templates.ExecuteTemplate(res, "login.html", formErr)
}
// logout: delete session and redirect to home
func (app *AuthCookie) LogoutPage(res http.ResponseWriter, req *http.Request) {
app.SaveUsername("", res, req)
app.RedirectHome(res, req)
}