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/context/base.go

@@ -149,16 +149,6 @@ func (b *Base) PlainText(status int, text string) {
 // Redirect redirects the request
 func (b *Base) Redirect(location string, status ...int) {
 	code := util.OptionalArg(status, http.StatusSeeOther)
-
-	if !httplib.IsRelativeURL(location) {
-		// Some browsers (Safari) have buggy behavior for Cookie + Cache + External Redirection, eg: /my-path => https://other/path
-		// 1. the first request to "/my-path" contains cookie
-		// 2. some time later, the request to "/my-path" doesn't contain cookie (caused by Prevent web tracking)
-		// 3. Gitea's Sessioner doesn't see the session cookie, so it generates a new session id, and returns it to browser
-		// 4. then the browser accepts the empty session, then the user is logged out
-		// So in this case, we should remove the session cookie from the response header
-		removeSessionCookieHeader(b.Resp)
-	}
 	// In case the request is made by "fetch-action" module, make JS redirect to the new location
 	// Otherwise, the JS fetch will follow the redirection and read a "login" page, embed it to the current page, which is not expected.
 	if httplib.IsGiteaFetchActionRequest(b.Req) {

services/context/base_test.go

@@ -21,27 +21,6 @@ func TestMain(m *testing.M) {
 
 func TestRedirect(t *testing.T) {
 	req, _ := http.NewRequest(http.MethodGet, "/", nil)
-
-	cases := []struct {
-		url  string
-		keep bool
-	}{
-		{"http://test", false},
-		{"https://test", false},
-		{"//test", false},
-		{"/://test", true},
-		{"/test", true},
-	}
-	for _, c := range cases {
-		resp := httptest.NewRecorder()
-		b := NewBaseContextForTest(t, resp, req)
-		resp.Header().Add("Set-Cookie", (&http.Cookie{Name: setting.SessionConfig.CookieName, Value: "dummy"}).String())
-		b.Redirect(c.url)
-		has := resp.Header().Get("Set-Cookie") == "i_like_gitea=dummy"
-		assert.Equal(t, c.keep, has, "url = %q", c.url)
-	}
-
-	req, _ = http.NewRequest(http.MethodGet, "/", nil)
 	resp := httptest.NewRecorder()
 	req.Header.Add("X-Gitea-Fetch-Action", "1")
 	b := NewBaseContextForTest(t, resp, req)

services/context/context_cookie.go

@@ -4,26 +4,11 @@
 package context
 
 import (
-	"net/http"
-	"strings"
-
-	"gitea.dev/modules/setting"
 	"gitea.dev/modules/web/middleware"
 )
 
 const CookieNameFlash = "gitea_flash"
 
-func removeSessionCookieHeader(w http.ResponseWriter) {
-	cookies := w.Header()["Set-Cookie"]
-	w.Header().Del("Set-Cookie")
-	for _, cookie := range cookies {
-		if strings.HasPrefix(cookie, setting.SessionConfig.CookieName+"=") {
-			continue
-		}
-		w.Header().Add("Set-Cookie", cookie)
-	}
-}
-
 // SetSiteCookie convenience function to set most cookies consistently
 func (ctx *Context) SetSiteCookie(name, value string, maxAge int) {
 	middleware.SetSiteCookie(ctx.Resp, name, value, maxAge)

services/context/context_test.go

@@ -18,16 +18,6 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestRemoveSessionCookieHeader(t *testing.T) {
-	w := httptest.NewRecorder()
-	w.Header().Add("Set-Cookie", (&http.Cookie{Name: setting.SessionConfig.CookieName, Value: "foo"}).String())
-	w.Header().Add("Set-Cookie", (&http.Cookie{Name: "other", Value: "bar"}).String())
-	assert.Len(t, w.Header().Values("Set-Cookie"), 2)
-	removeSessionCookieHeader(w)
-	assert.Len(t, w.Header().Values("Set-Cookie"), 1)
-	assert.Contains(t, "other=bar", w.Header().Get("Set-Cookie"))
-}
-
 func TestServerErrorFetchActionRespondsJSON(t *testing.T) {
 	req, _ := http.NewRequest(http.MethodPost, "/", nil)
 	req.Header.Add("X-Gitea-Fetch-Action", "1")