Add Federation specific URL validation

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]*$`)
 	validUsernamePatternWithoutDots = regexp.MustCompile(`^[\da-zA-Z][-\w]*$`)