Simple blogging system written in Go https://goblog.app
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package main
import (
"bytes"
"context"
"encoding/base64"
"encoding/json"
"io"
"net/http"
"strings"
"github.com/pquerna/otp/totp"
"go.goblog.app/app/pkgs/contenttype"
)
const loggedInKey contextKey = "loggedIn"
// Check if credentials are correct
func (a *goBlog) checkCredentials(username, password, totpPasscode string) bool {
return username == a.cfg.User.Nick &&
password == a.cfg.User.Password &&
(a.cfg.User.TOTP == "" || totp.Validate(totpPasscode, a.cfg.User.TOTP))
}
// Check if app passwords are correct
func (a *goBlog) checkAppPasswords(username, password string) bool {
for _, apw := range a.cfg.User.AppPasswords {
if apw.Username == username && apw.Password == password {
return true
}
}
return false
}
// Check if cookie is known and logged in
func (a *goBlog) checkLoginCookie(r *http.Request) bool {
ses, err := a.loginSessions.Get(r, "l")
if err == nil && ses != nil {
if login, ok := ses.Values["login"]; ok && login.(bool) {
return true
}
}
return false
}
// Middleware to force login
func (a *goBlog) authMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Check if already logged in
if a.isLoggedIn(r) {
next.ServeHTTP(w, r)
return
}
// Show login form
w.Header().Set("Cache-Control", "no-store,max-age=0")
w.Header().Set("X-Robots-Tag", "noindex")
h, _ := json.Marshal(r.Header)
b, _ := io.ReadAll(io.LimitReader(r.Body, 20*1000*1000)) // Only allow 20 MB
_ = r.Body.Close()
if len(b) == 0 {
// Maybe it's a form
_ = r.ParseForm()
b = []byte(r.PostForm.Encode())
}
a.render(w, r, templateLogin, &renderData{
Data: map[string]interface{}{
"loginmethod": r.Method,
"loginheaders": base64.StdEncoding.EncodeToString(h),
"loginbody": base64.StdEncoding.EncodeToString(b),
"totp": a.cfg.User.TOTP != "",
},
})
})
}
// Middleware to check if the request is a login request
func (a *goBlog) checkIsLogin(next http.Handler) http.Handler {
return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
if !a.checkLogin(rw, r) {
next.ServeHTTP(rw, r)
}
})
}
// Checks login and returns true if it already served an error
func (a *goBlog) checkLogin(w http.ResponseWriter, r *http.Request) bool {
if r.Method != http.MethodPost {
return false
}
if !strings.Contains(r.Header.Get(contentType), contenttype.WWWForm) {
return false
}
if r.FormValue("loginaction") != "login" {
return false
}
// Check credential
if !a.checkCredentials(r.FormValue("username"), r.FormValue("password"), r.FormValue("token")) {
a.serveError(w, r, "Incorrect credentials", http.StatusUnauthorized)
return true
}
// Prepare original request
loginbody, _ := base64.StdEncoding.DecodeString(r.FormValue("loginbody"))
req, _ := http.NewRequest(r.FormValue("loginmethod"), r.RequestURI, bytes.NewReader(loginbody))
// Copy original headers
loginheaders, _ := base64.StdEncoding.DecodeString(r.FormValue("loginheaders"))
var headers http.Header
_ = json.Unmarshal(loginheaders, &headers)
for k, v := range headers {
req.Header[k] = v
}
// Cookie
ses, err := a.loginSessions.Get(r, "l")
if err != nil {
a.serveError(w, r, err.Error(), http.StatusInternalServerError)
return true
}
ses.Values["login"] = true
err = a.loginSessions.Save(r, w, ses)
if err != nil {
a.serveError(w, r, err.Error(), http.StatusInternalServerError)
return true
}
// Serve original request
setLoggedIn(req, true)
a.d.ServeHTTP(w, req)
return true
}
func (a *goBlog) isLoggedIn(r *http.Request) bool {
// Check if context key already set
if loggedIn, ok := r.Context().Value(loggedInKey).(bool); ok {
return loggedIn
}
// Check app passwords
if username, password, ok := r.BasicAuth(); ok && a.checkAppPasswords(username, password) {
setLoggedIn(r, true)
return true
}
// Check session cookie
if a.checkLoginCookie(r) {
setLoggedIn(r, true)
return true
}
// Not logged in
return false
}
// Set request context value
func setLoggedIn(r *http.Request, loggedIn bool) {
// Overwrite the value of r (r is a pointer)
(*r) = *(r.WithContext(context.WithValue(r.Context(), loggedInKey, loggedIn)))
}
// HandlerFunc to redirect to home after login
// Need to set auth middleware!
func serveLogin(w http.ResponseWriter, r *http.Request) {
http.Redirect(w, r, "/", http.StatusFound)
}
// HandlerFunc to delete login session and cookie
func (a *goBlog) serveLogout(w http.ResponseWriter, r *http.Request) {
if ses, err := a.loginSessions.Get(r, "l"); err == nil && ses != nil {
_ = a.loginSessions.Delete(r, w, ses)
}
http.Redirect(w, r, "/", http.StatusFound)
}