fix support for regexp groups greater than 10 (#6033)

internal/staticsources/handler.go

@@ -32,10 +32,8 @@ func emptyTimer() *time.Timer {
 }
 
 func resolveSource(s string, matches []string, query string) string {
-	if len(matches) > 1 {
-		for i, ma := range matches[1:] {
-			s = strings.ReplaceAll(s, "$G"+strconv.FormatInt(int64(i+1), 10), ma)
-		}
+	for i := len(matches) - 1; i >= 1; i-- {
+		s = strings.ReplaceAll(s, "$G"+strconv.FormatInt(int64(i), 10), matches[i])
 	}
 
 	s = strings.ReplaceAll(s, "$MTX_QUERY", query)

internal/staticsources/handler_test.go

@@ -105,6 +105,13 @@ func TestResolveSource(t *testing.T) {
 			query:    "",
 			expected: "udp+rtp://192.168.1.100:5000",
 		},
+		{
+			name:     "multi digit group substitution",
+			source:   "rtsp://example.com/$G10",
+			matches:  []string{"full", "g1", "g2", "g3", "g4", "g5", "g6", "g7", "g8", "g9", "g10"},
+			query:    "",
+			expected: "rtsp://example.com/g10",
+		},
 	} {
 		t.Run(ca.name, func(t *testing.T) {
 			result := resolveSource(ca.source, ca.matches, ca.query)