Ignore port for OAuth2 loopback redirect URIs (go-gitea#21293) (go-gitea#21373)

Backport go-gitea#21293

Following https://datatracker.ietf.org/doc/html/rfc8252#section-7.3

Fixes go-gitea#21285

Author: tyroneyeh

models/auth/oauth2.go

@@ -10,6 +10,7 @@ import (
 	"encoding/base32"
 	"encoding/base64"
 	"fmt"
+	"net"
 	"net/url"
 	"strings"
 
@@ -56,6 +57,18 @@ func (app *OAuth2Application) PrimaryRedirectURI() string {
 
 // ContainsRedirectURI checks if redirectURI is allowed for app
 func (app *OAuth2Application) ContainsRedirectURI(redirectURI string) bool {
+	uri, err := url.Parse(redirectURI)
+	// ignore port for http loopback uris following https://datatracker.ietf.org/doc/html/rfc8252#section-7.3
+	if err == nil && uri.Scheme == "http" && uri.Port() != "" {
+		ip := net.ParseIP(uri.Hostname())
+		if ip != nil && ip.IsLoopback() {
+			// strip port
+			uri.Host = uri.Hostname()
+			if util.IsStringInSlice(uri.String(), app.RedirectURIs, true) {
+				return true
+			}
+		}
+	}
 	return util.IsStringInSlice(redirectURI, app.RedirectURIs, true)
 }
 

models/auth/oauth2_test.go

@@ -42,6 +42,26 @@ func TestOAuth2Application_ContainsRedirectURI(t *testing.T) {
 	assert.False(t, app.ContainsRedirectURI("d"))
 }
 
+func TestOAuth2Application_ContainsRedirectURI_WithPort(t *testing.T) {
+	app := &OAuth2Application{
+		RedirectURIs: []string{"http://127.0.0.1/", "http://::1/", "http://192.168.0.1/", "http://intranet/", "https://127.0.0.1/"},
+	}
+
+	// http loopback uris should ignore port
+	// https://datatracker.ietf.org/doc/html/rfc8252#section-7.3
+	assert.True(t, app.ContainsRedirectURI("http://127.0.0.1:3456/"))
+	assert.True(t, app.ContainsRedirectURI("http://127.0.0.1/"))
+	assert.True(t, app.ContainsRedirectURI("http://[::1]:3456/"))
+
+	// not http
+	assert.False(t, app.ContainsRedirectURI("https://127.0.0.1:3456/"))
+	// not loopback
+	assert.False(t, app.ContainsRedirectURI("http://192.168.0.1:9954/"))
+	assert.False(t, app.ContainsRedirectURI("http://intranet:3456/"))
+	// unparseable
+	assert.False(t, app.ContainsRedirectURI(":"))
+}
+
 func TestOAuth2Application_ValidateClientSecret(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	app := unittest.AssertExistsAndLoadBean(t, &OAuth2Application{ID: 1}).(*OAuth2Application)