From 655e0d0fd6bf7c8d63e59c846f3e664cfc2df715 Mon Sep 17 00:00:00 2001
From: aler9 <46489434+aler9@users.noreply.github.com>
Date: Sun, 1 Nov 2020 17:48:00 +0100
Subject: [PATCH] implement fallback (#104)

---
 conf/pathconf.go       | 12 ++++++++++++
 main_test.go           | 38 ++++++++++++++++++++++++++++++++++++++
 path/path.go           |  7 +++++++
 rtsp-simple-server.yml |  3 +++
 4 files changed, 60 insertions(+)

diff --git a/conf/pathconf.go b/conf/pathconf.go
index 3bd8acca..5efa8f37 100644
--- a/conf/pathconf.go
+++ b/conf/pathconf.go
@@ -24,6 +24,7 @@ type PathConf struct {
 	SourceOnDemandStartTimeout time.Duration            `yaml:"sourceOnDemandStartTimeout"`
 	SourceOnDemandCloseAfter   time.Duration            `yaml:"sourceOnDemandCloseAfter"`
 	SourceRedirect             string                   `yaml:"sourceRedirect"`
+	Fallback                   string                   `yaml:"fallback"`
 	RunOnInit                  string                   `yaml:"runOnInit"`
 	RunOnInitRestart           bool                     `yaml:"runOnInitRestart"`
 	RunOnDemand                string                   `yaml:"runOnDemand"`
@@ -150,6 +151,17 @@ func (pconf *PathConf) fillAndCheck(name string) error {
 		pconf.SourceOnDemandCloseAfter = 10 * time.Second
 	}
 
+	if pconf.Fallback != "" {
+		u, err := url.Parse(pconf.Fallback)
+		if err != nil {
+			return fmt.Errorf("'%s' is not a valid rtsp url", pconf.Fallback)
+		}
+
+		if u.Scheme != "rtsp" {
+			return fmt.Errorf("'%s' is not a valid rtsp url", pconf.Fallback)
+		}
+	}
+
 	if pconf.PublishUser != "" {
 		if !reUserPass.MatchString(pconf.PublishUser) {
 			return fmt.Errorf("publish username contains unsupported characters (supported are %s)", userPassSupportedChars)
diff --git a/main_test.go b/main_test.go
index 2f7633f7..cba026a3 100644
--- a/main_test.go
+++ b/main_test.go
@@ -689,6 +689,44 @@ func TestRedirect(t *testing.T) {
 	require.Equal(t, 0, code)
 }
 
+func TestFallback(t *testing.T) {
+	p1, err := testProgram("paths:\n" +
+		"  path1:\n" +
+		"    fallback: rtsp://" + ownDockerIp + ":8554/path2\n" +
+		"  path2:\n")
+	require.NoError(t, err)
+	defer p1.close()
+
+	time.Sleep(1 * time.Second)
+
+	cnt1, err := newContainer("ffmpeg", "source", []string{
+		"-re",
+		"-stream_loop", "-1",
+		"-i", "/emptyvideo.ts",
+		"-c", "copy",
+		"-f", "rtsp",
+		"-rtsp_transport", "udp",
+		"rtsp://" + ownDockerIp + ":8554/path2",
+	})
+	require.NoError(t, err)
+	defer cnt1.close()
+
+	time.Sleep(1 * time.Second)
+
+	cnt2, err := newContainer("ffmpeg", "dest", []string{
+		"-rtsp_transport", "udp",
+		"-i", "rtsp://" + ownDockerIp + ":8554/path1",
+		"-vframes", "1",
+		"-f", "image2",
+		"-y", "/dev/null",
+	})
+	require.NoError(t, err)
+	defer cnt2.close()
+
+	code := cnt2.wait()
+	require.Equal(t, 0, code)
+}
+
 func TestRunOnDemand(t *testing.T) {
 	p1, err := testProgram("paths:\n" +
 		"  all:\n" +
diff --git a/path/path.go b/path/path.go
index f8635467..7c325f33 100644
--- a/path/path.go
+++ b/path/path.go
@@ -612,6 +612,13 @@ func (pa *Path) onClientDescribe(c *client.Client) {
 		return
 
 	case sourceStateNotReady:
+		if pa.conf.Fallback != "" {
+			pa.addClient(c, clientStatePreRemove)
+			pa.removeClient(c)
+			c.OnPathDescribeData(nil, pa.conf.Fallback, nil)
+			return
+		}
+
 		pa.addClient(c, clientStatePreRemove)
 		pa.removeClient(c)
 		c.OnPathDescribeData(nil, "", fmt.Errorf("no one is publishing to path '%s'", pa.name))
diff --git a/rtsp-simple-server.yml b/rtsp-simple-server.yml
index 6115a37f..58c8165d 100644
--- a/rtsp-simple-server.yml
+++ b/rtsp-simple-server.yml
@@ -66,6 +66,9 @@ paths:
     # redirected to.
     sourceRedirect:
 
+    # fallback url to redirect clients to when nobody is publishing to this path
+    fallback:
+
     # username required to publish.
     publishUser:
     # password required to publish.