From beb82045ffd31dca4ef0046cf7c7da05f0fa19a1 Mon Sep 17 00:00:00 2001
From: Alex X <alexey.khit@gmail.com>
Date: Fri, 29 Aug 2025 16:45:19 +0300
Subject: [PATCH] Fix yet another broken Content-Base for RTSP #1852

---
 pkg/rtsp/helpers.go   | 27 +++++++++++++++++++++++----
 pkg/rtsp/rtsp_test.go | 10 ++++++++--
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/pkg/rtsp/helpers.go b/pkg/rtsp/helpers.go
index d8ed1685..c73bd0a2 100644
--- a/pkg/rtsp/helpers.go
+++ b/pkg/rtsp/helpers.go
@@ -116,20 +116,39 @@ func findFmtpLine(payloadType uint8, descriptions []*sdp.MediaDescription) strin
 // urlParse fix bugs:
 // 1. Content-Base: rtsp://::ffff:192.168.1.123/onvif/profile.1/
 // 2. Content-Base: rtsp://rtsp://turret2-cam.lan:554/stream1/
+// 3. Content-Base: 192.168.253.220:1935/
 func urlParse(rawURL string) (*url.URL, error) {
 	// fix https://github.com/AlexxIT/go2rtc/issues/830
 	if strings.HasPrefix(rawURL, "rtsp://rtsp://") {
 		rawURL = rawURL[7:]
 	}
 
+	// fix https://github.com/AlexxIT/go2rtc/issues/1852
+	if !strings.Contains(rawURL, "://") {
+		rawURL = "rtsp://" + rawURL
+	}
+
 	u, err := url.Parse(rawURL)
 	if err != nil && strings.HasSuffix(err.Error(), "after host") {
-		if i1 := strings.Index(rawURL, "://"); i1 > 0 {
-			if i2 := strings.IndexByte(rawURL[i1+3:], '/'); i2 > 0 {
-				return urlParse(rawURL[:i1+3+i2] + ":" + rawURL[i1+3+i2:])
-			}
+		if i := indexN(rawURL, '/', 3); i > 0 {
+			return urlParse(rawURL[:i] + ":" + rawURL[i:])
 		}
 	}
 
 	return u, err
 }
+
+func indexN(s string, c byte, n int) int {
+	var offset int
+	for {
+		i := strings.IndexByte(s[offset:], c)
+		if i < 0 {
+			break
+		}
+		if n--; n == 0 {
+			return offset + i
+		}
+		offset += i + 1
+	}
+	return -1
+}
diff --git a/pkg/rtsp/rtsp_test.go b/pkg/rtsp/rtsp_test.go
index 14c99803..282c04f8 100644
--- a/pkg/rtsp/rtsp_test.go
+++ b/pkg/rtsp/rtsp_test.go
@@ -11,14 +11,20 @@ func TestURLParse(t *testing.T) {
 	// https://github.com/AlexxIT/WebRTC/issues/395
 	base := "rtsp://::ffff:192.168.1.123/onvif/profile.1/"
 	u, err := urlParse(base)
-	assert.Empty(t, err)
+	assert.NoError(t, err)
 	assert.Equal(t, "::ffff:192.168.1.123:", u.Host)
 
 	// https://github.com/AlexxIT/go2rtc/issues/208
 	base = "rtsp://rtsp://turret2-cam.lan:554/stream1/"
 	u, err = urlParse(base)
-	assert.Empty(t, err)
+	assert.NoError(t, err)
 	assert.Equal(t, "turret2-cam.lan:554", u.Host)
+
+	// https://github.com/AlexxIT/go2rtc/issues/1852
+	base = "192.168.253.220:1935/"
+	u, err = urlParse(base)
+	assert.NoError(t, err)
+	assert.Equal(t, "192.168.253.220:1935", u.Host)
 }
 
 func TestBugSDP1(t *testing.T) {