Add full shop application: Go backend, PostgreSQL, Docker, Caddy and admin panel.

internal/auth/session.go

@@ -0,0 +1,94 @@
+package auth
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	cookieName = "shop_session"
+	sessionTTL = 24 * time.Hour
+)
+
+type Session struct {
+	secret []byte
+}
+
+func NewSession(secret string) *Session {
+	return &Session{secret: []byte(secret)}
+}
+
+func (s *Session) Create(email string) (string, error) {
+	exp := time.Now().Add(sessionTTL).Unix()
+	payload := fmt.Sprintf("%s|%d", email, exp)
+	sig := s.sign(payload)
+	token := base64.URLEncoding.EncodeToString([]byte(payload + "|" + sig))
+	return token, nil
+}
+
+func (s *Session) Validate(token string) (string, bool) {
+	raw, err := base64.URLEncoding.DecodeString(token)
+	if err != nil {
+		return "", false
+	}
+
+	parts := strings.Split(string(raw), "|")
+	if len(parts) != 3 {
+		return "", false
+	}
+
+	email, expStr, sig := parts[0], parts[1], parts[2]
+	payload := email + "|" + expStr
+
+	if !hmac.Equal([]byte(sig), []byte(s.sign(payload))) {
+		return "", false
+	}
+
+	exp, err := strconv.ParseInt(expStr, 10, 64)
+	if err != nil || time.Now().Unix() > exp {
+		return "", false
+	}
+
+	return email, true
+}
+
+func (s *Session) SetCookie(w http.ResponseWriter, token string) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     cookieName,
+		Value:    token,
+		Path:     "/admin",
+		HttpOnly: true,
+		SameSite: http.SameSiteLaxMode,
+		MaxAge:   int(sessionTTL.Seconds()),
+	})
+}
+
+func (s *Session) ClearCookie(w http.ResponseWriter) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     cookieName,
+		Value:    "",
+		Path:     "/admin",
+		HttpOnly: true,
+		MaxAge:   -1,
+	})
+}
+
+func (s *Session) FromRequest(r *http.Request) (string, bool) {
+	c, err := r.Cookie(cookieName)
+	if err != nil {
+		return "", false
+	}
+	return s.Validate(c.Value)
+}
+
+func (s *Session) sign(payload string) string {
+	mac := hmac.New(sha256.New, s.secret)
+	mac.Write([]byte(payload))
+	return base64.URLEncoding.EncodeToString(mac.Sum(nil))
+}