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package app
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import (
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"context"
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"crypto/rand"
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"crypto/sha256"
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"encoding/base64"
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"encoding/hex"
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"net/http"
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"time"
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)
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const (
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cookieName = "spread_session"
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sessionTTL = 30 * 24 * time.Hour
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)
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type ctxKey int
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const (
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userKey ctxKey = iota
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subKey
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csrfKey
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)
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func hashToken(raw string) string {
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sum := sha256.Sum256([]byte(raw))
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return hex.EncodeToString(sum[:])
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}
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// randomToken returns a 256-bit URL-safe random string.
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func randomToken() string {
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buf := make([]byte, 32)
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_, _ = rand.Read(buf)
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return base64.RawURLEncoding.EncodeToString(buf)
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}
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func (a *App) createSession(ctx context.Context, userID int64) (string, error) {
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raw := randomToken()
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_, err := a.pool.Exec(ctx,
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`INSERT INTO sessions (token_hash, user_id, expires_at) VALUES ($1, $2, $3)`,
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hashToken(raw), userID, time.Now().Add(sessionTTL))
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if err != nil {
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return "", err
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}
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return raw, nil
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}
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func (a *App) lookupSession(ctx context.Context, raw string) (User, Subscriber, error) {
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var u User
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err := a.pool.QueryRow(ctx,
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`SELECT u.id, u.subscriber_id, u.email, u.name
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FROM sessions s JOIN users u ON u.id = s.user_id
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WHERE s.token_hash = $1 AND s.expires_at > now()`,
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hashToken(raw)).Scan(&u.ID, &u.SubscriberID, &u.Email, &u.Name)
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if err != nil {
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return User{}, Subscriber{}, err
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}
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sub, err := a.subscriber(ctx, u.SubscriberID)
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return u, sub, err
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}
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func (a *App) destroySession(ctx context.Context, raw string) {
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_, _ = a.pool.Exec(ctx, `DELETE FROM sessions WHERE token_hash = $1`, hashToken(raw))
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}
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func (a *App) setSessionCookie(w http.ResponseWriter, raw string) {
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http.SetCookie(w, &http.Cookie{
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Name: cookieName,
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Value: raw,
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Path: "/",
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HttpOnly: true,
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Secure: a.secureCookie,
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SameSite: http.SameSiteLaxMode,
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Expires: time.Now().Add(sessionTTL),
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})
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}
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func (a *App) clearSessionCookie(w http.ResponseWriter) {
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http.SetCookie(w, &http.Cookie{
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Name: cookieName,
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Value: "",
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Path: "/",
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HttpOnly: true,
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Secure: a.secureCookie,
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SameSite: http.SameSiteLaxMode,
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MaxAge: -1,
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})
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}
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// current returns the logged-in user and subscriber from the request context.
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func current(r *http.Request) (User, Subscriber, bool) {
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u, ok := r.Context().Value(userKey).(User)
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if !ok {
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return User{}, Subscriber{}, false
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}
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s, _ := r.Context().Value(subKey).(Subscriber)
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return u, s, true
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}
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// load attaches the session user/subscriber to the request context if a valid
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// session cookie is present. It never redirects.
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func (a *App) load(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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if c, err := r.Cookie(cookieName); err == nil && c.Value != "" {
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if u, s, err := a.lookupSession(r.Context(), c.Value); err == nil {
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ctx := context.WithValue(r.Context(), userKey, u)
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ctx = context.WithValue(ctx, subKey, s)
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r = r.WithContext(ctx)
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}
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}
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next.ServeHTTP(w, r)
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})
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}
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// requireAuth redirects to /login when there is no session.
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func (a *App) requireAuth(fn http.HandlerFunc) http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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if _, _, ok := current(r); !ok {
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http.Redirect(w, r, "/login", http.StatusSeeOther)
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return
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}
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fn(w, r)
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}
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}
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// requireInternal requires a session belonging to the internal subscriber.
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func (a *App) requireInternal(fn http.HandlerFunc) http.HandlerFunc {
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return a.requireAuth(func(w http.ResponseWriter, r *http.Request) {
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if _, s, _ := current(r); !s.IsInternal {
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http.Redirect(w, r, "/app", http.StatusSeeOther)
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return
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}
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fn(w, r)
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})
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}
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