Add never option to PUBLIC_URL_DETECTION configuration (#36785)

Follow up #34250

Docs: https://gitea.com/gitea/docs/pulls/353

---------

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

custom/conf/app.example.ini

@@ -74,6 +74,7 @@ RUN_USER = ; git
 ;; especially when the Gitea instance needs to be accessed in a container network.
 ;; * legacy: detect the public URL from "Host" header if "X-Forwarded-Proto" header exists, otherwise use "ROOT_URL".
 ;; * auto: always use "Host" header, and also use "X-Forwarded-Proto" header if it exists. If no "Host" header, use "ROOT_URL".
+;; * never: always use "ROOT_URL", never detect from request headers.
 ;PUBLIC_URL_DETECTION = legacy
 ;;
 ;; For development purpose only. It makes Gitea handle sub-path ("/sub-path/owner/repo/...") directly when debugging without a reverse proxy.

modules/httplib/url.go

@@ -72,6 +72,10 @@ func GuessCurrentAppURL(ctx context.Context) string {
 
 // GuessCurrentHostURL tries to guess the current full host URL (no sub-path) by http headers, there is no trailing slash.
 func GuessCurrentHostURL(ctx context.Context) string {
+	// "never" means always trust ROOT_URL and skip any request header detection.
+	if setting.PublicURLDetection == setting.PublicURLNever {
+		return strings.TrimSuffix(setting.AppURL, setting.AppSubURL+"/")
+	}
 	// Try the best guess to get the current host URL (will be used for public URL) by http headers.
 	// At the moment, if site admin doesn't configure the proxy headers correctly, then Gitea would guess wrong.
 	// There are some cases:

modules/httplib/url_test.go

@@ -77,6 +77,21 @@ func TestGuessCurrentHostURL(t *testing.T) {
 		ctx = context.WithValue(t.Context(), RequestContextKey, &http.Request{Host: "req-host:3000", Header: headersWithProto})
 		assert.Equal(t, "https://req-host:3000", GuessCurrentHostURL(ctx))
 	})
+
+	t.Run("Never", func(t *testing.T) {
+		defer test.MockVariableValue(&setting.PublicURLDetection, setting.PublicURLNever)()
+
+		assert.Equal(t, "http://cfg-host", GuessCurrentHostURL(t.Context()))
+
+		ctx := context.WithValue(t.Context(), RequestContextKey, &http.Request{Host: "req-host:3000"})
+		assert.Equal(t, "http://cfg-host", GuessCurrentHostURL(ctx))
+
+		ctx = context.WithValue(t.Context(), RequestContextKey, &http.Request{Host: "req-host:3000", TLS: &tls.ConnectionState{}})
+		assert.Equal(t, "http://cfg-host", GuessCurrentHostURL(ctx))
+
+		ctx = context.WithValue(t.Context(), RequestContextKey, &http.Request{Host: "req-host:3000", Header: headersWithProto})
+		assert.Equal(t, "http://cfg-host", GuessCurrentHostURL(ctx))
+	})
 }
 
 func TestMakeAbsoluteURL(t *testing.T) {

modules/setting/server.go

@@ -44,6 +44,7 @@ const (
 const (
 	PublicURLAuto   = "auto"
 	PublicURLLegacy = "legacy"
+	PublicURLNever  = "never"
 )
 
 // Server settings
@@ -286,7 +287,7 @@ func loadServerFrom(rootCfg ConfigProvider) {
 	defaultAppURL := string(Protocol) + "://" + Domain + ":" + HTTPPort
 	AppURL = sec.Key("ROOT_URL").MustString(defaultAppURL)
 	PublicURLDetection = sec.Key("PUBLIC_URL_DETECTION").MustString(PublicURLLegacy)
-	if PublicURLDetection != PublicURLAuto && PublicURLDetection != PublicURLLegacy {
+	if PublicURLDetection != PublicURLAuto && PublicURLDetection != PublicURLLegacy && PublicURLDetection != PublicURLNever {
 		log.Fatal("Invalid PUBLIC_URL_DETECTION value: %s", PublicURLDetection)
 	}