From 584af0486dd8c91707d9f7640bbe85db189c61e2 Mon Sep 17 00:00:00 2001
From: erik <erik.seiert@meissa-gmbh.de>
Date: Wed, 20 Mar 2024 13:13:23 +0100
Subject: [PATCH] Add Federation specific URL validation

---
 modules/validation/helpers.go | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/modules/validation/helpers.go b/modules/validation/helpers.go
index 567ad867fe..5edfe8d3c2 100644
--- a/modules/validation/helpers.go
+++ b/modules/validation/helpers.go
@@ -7,6 +7,7 @@ import (
 	"net"
 	"net/url"
 	"regexp"
+	"strconv"
 	"strings"
 
 	"code.gitea.io/gitea/modules/setting"
@@ -116,6 +117,32 @@ func IsValidExternalTrackerURLFormat(uri string) bool {
 	return true
 }
 
+func IsValidForgejoActivityPubURL(url string) bool {
+	if !IsValidURL(url) {
+		return false
+	}
+	if !strings.Contains(url, "api/v1/activitypub") {
+		return false
+	}
+	return true
+}
+
+func IsValidFederatedRepoURL(url string) bool {
+	if !IsValidForgejoActivityPubURL(url) {
+		return false
+	}
+	if !strings.Contains(url, "repository-id") {
+		return false
+	}
+	splitURL := strings.Split(url, "/")
+	repoIDIndex := len(splitURL) - 1
+	// Is there a valid integer denoting a repo id?
+	if _, err := strconv.Atoi(splitURL[repoIDIndex]); err != nil {
+		return false
+	}
+	return true
+}
+
 var (
 	validUsernamePatternWithDots    = regexp.MustCompile(`^[\da-zA-Z][-.\w]*$`)
 	validUsernamePatternWithoutDots = regexp.MustCompile(`^[\da-zA-Z][-\w]*$`)