Added session cookie and logout for admin

auth/session.go

@@ -0,0 +1,69 @@
+package auth
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"net/http"
+	"sync"
+	"time"
+)
+
+var (
+	sessions = map[string]time.Time{}
+	mu       sync.Mutex
+)
+
+func GenerateSession() (string, error) {
+	bytes := make([]byte, 32)
+	_, err := rand.Read(bytes)
+	if err != nil {
+		return "", err
+	}
+	token := hex.EncodeToString(bytes)
+
+	mu.Lock()
+	sessions[token] = time.Now()
+	mu.Unlock()
+
+	return token, nil
+}
+
+func IsLoggedIn(r *http.Request) bool {
+	cookie, err := r.Cookie("session")
+	if err != nil {
+		return false
+	}
+
+	mu.Lock()
+	_, exists := sessions[cookie.Value]
+	mu.Unlock()
+
+	return exists
+}
+
+func SetSessionCookie(w http.ResponseWriter, token string) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     "session",
+		Value:    token,
+		Path:     "/",
+		HttpOnly: true,
+		SameSite: http.SameSiteLaxMode,
+	})
+}
+
+func ClearSession(w http.ResponseWriter, r *http.Request) {
+	cookie, err := r.Cookie("session")
+	if err == nil {
+		mu.Lock()
+		delete(sessions, cookie.Value)
+		mu.Unlock()
+	}
+
+	http.SetCookie(w, &http.Cookie{
+		Name:     "session",
+		Value:    "",
+		Path:     "/",
+		MaxAge:   -1,
+		HttpOnly: true,
+	})
+}

handlers/auth.go

@@ -74,7 +74,22 @@ func Login(tmpl *template.Template) http.HandlerFunc {
 			return
 		}
 
-		// TODO: create a session so the admin stays logged in
+		token, err := auth.GenerateSession()
+		if err != nil {
+			tmpl.Execute(w, map[string]string{
+				"SiteName": Cfg.SiteName,
+				"Error":    "Something went wrong. Please try again.",
+			})
+			return
+		}
+		auth.SetSessionCookie(w, token)
 		http.Redirect(w, r, "/admin", http.StatusSeeOther)
 	}
 }
+
+func Logout() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		auth.ClearSession(w, r)
+		http.Redirect(w, r, "/", http.StatusSeeOther)
+	}
+}

main.go

@@ -40,6 +40,7 @@ func main() {
 
 	http.HandleFunc("/setup", handlers.Setup(tmpl.Lookup("setup.html")))
 	http.HandleFunc("/login", handlers.Login(tmpl.Lookup("login.html")))
+	http.HandleFunc("/logout", handlers.Logout())
 
 	log.Printf("Starting filehost on %s\n", cfg.Port)
 	log.Fatal(http.ListenAndServe(cfg.Port, nil))