refactor!: move go-chi/session into Gitea (#39504)

The `gitea.com/go-chi/session` package only exists for Gitea, so it
moves into `modules/session` to fix its bugs directly. Fixes the flake
in
https://github.com/go-gitea/gitea/actions/runs/36726154500/job/109923538400.

- Sessions are only written back when changed, so a read-only request
can't revert a concurrent change or restore a logged-out session, like
https://github.com/go-macaron/session/commit/ae808a4a4660c802965c834299ab08f167effd12
- The session cookie is only set once a session holds data
- Every backend refreshes the expiry on load and file sessions are
written atomically
- Also fix  https://github.com/go-gitea/gitea/issues/36176

## ⚠️ BREAKING ⚠️

* the `mysql`, `postgres`, `couchbase` and `memcache` session providers
are removed, use `file`, `db` or `redis` instead
* login-related cookies are renamed to `gitea_session` and
`gitea_remember`, if you'd like to use the old names, set `COOKIE_NAME`
and `COOKIE_REMEMBER_NAME` in app.ini

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/auth/auth.go

@@ -40,19 +40,14 @@ func Init() {
 // handleSignInNonInteractive clears existing session variables and stores new ones for the specified user object
 // it is mainly for middleware sign-in which doesn't need user's interaction.
 func handleSignInNonInteractive(resp http.ResponseWriter, req *http.Request, sess SessionStore, user *user_model.User) {
-	// We need to regenerate the session...
-	newSess, err := session.RegenerateSession(resp, req)
-	if err != nil {
-		log.Error(fmt.Sprintf("Error regenerating session: %v", err))
-	} else {
-		sess = newSess
-	}
-
+	sess.Regenerate(resp, req)
 	ClearSessionKeysForSignIn(sess)
-	err = sess.Set(session.KeyUID, user.ID)
-	if err != nil {
+	if err := sess.Set(session.KeyUID, user.ID); err != nil {
 		log.Error(fmt.Sprintf("Error setting session: %v", err))
 	}
+	if err := sess.Release(); err != nil { // save before a long-lived handler like a websocket runs
+		log.Error("Error saving session: %v", err)
+	}
 
 	opts := &user_service.UpdateOptions{SetLastLogin: true}
 	// Language setting of the user overwrites the one previously set

services/auth/reverseproxy_test.go

@@ -34,6 +34,16 @@ func TestReverseProxyIgnoresBot(t *testing.T) {
 	assert.Nil(t, user)
 }
 
+type releaseCountingStore struct {
+	session.Store
+	released int
+}
+
+func (s *releaseCountingStore) Release() error {
+	s.released++
+	return s.Store.Release()
+}
+
 func TestReverseProxyLastLogin(t *testing.T) {
 	require.NoError(t, unittest.PrepareTestDatabase())
 	defer test.MockVariableValue(&setting.ReverseProxyAuthUser, "X-WEBAUTH-USER")()
@@ -41,13 +51,15 @@ func TestReverseProxyLastLogin(t *testing.T) {
 	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
 	require.Zero(t, user.LastLoginUnix)
 
-	ctx, resp := contexttest.MockContext(t, "/", contexttest.MockContextOption{SessionStore: session.NewMockMemStore("reverse-proxy-last-login")})
+	sess := &releaseCountingStore{Store: session.NewMockMemStore("reverse-proxy-last-login")}
+	ctx, resp := contexttest.MockContext(t, "/", contexttest.MockContextOption{SessionStore: sess})
 	ctx.Req.Header.Set(setting.ReverseProxyAuthUser, user.Name)
 	rp := &ReverseProxy{CreateSession: true}
 
 	_, err := rp.Verify(ctx.Req, resp, ctx, ctx.Session)
 	require.NoError(t, err)
 	assert.NotZero(t, unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: user.ID}).LastLoginUnix)
+	assert.Equal(t, 1, sess.released)
 
 	user.LastLoginUnix = 1
 	require.NoError(t, user_model.UpdateUserCols(t.Context(), user, "last_login_unix"))
@@ -55,4 +67,5 @@ func TestReverseProxyLastLogin(t *testing.T) {
 	_, err = rp.Verify(ctx.Req, resp, ctx, ctx.Session)
 	require.NoError(t, err)
 	assert.EqualValues(t, 1, unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: user.ID}).LastLoginUnix) // no write without a new session
+	assert.Equal(t, 1, sess.released)
 }

services/auth/source/oauth2/store.go

@@ -32,7 +32,6 @@ func (st *SessionsStore) New(r *http.Request, name string) (*sessions.Session, e
 	return st.getOrNew(r, name, true)
 }
 
-// getOrNew gets the session from the chi-session if it exists. Override permits the overriding of an unexpected object.
 func (st *SessionsStore) getOrNew(r *http.Request, name string, override bool) (*sessions.Session, error) {
 	store := session_module.GetContextSession(r)
 
@@ -55,7 +54,7 @@ func (st *SessionsStore) getOrNew(r *http.Request, name string, override bool) (
 	}
 
 	session.IsNew = override
-	session.ID = store.ID() // Simply copy the session id from the chi store
+	session.ID = store.ID()
 
 	return session, store.Set(name, session)
 }
@@ -65,7 +64,7 @@ func (st *SessionsStore) Save(r *http.Request, w http.ResponseWriter, session *s
 	store := session_module.GetContextSession(r)
 
 	if session.IsNew {
-		_, _ = session_module.RegenerateSession(w, r)
+		store.Regenerate(w, r)
 		session.IsNew = false
 	}