Configure all mounts to fall back to silence

Unless an explicit fallback is configured. Untested.

debian/rules

@@ -12,6 +12,11 @@ override_dh_auto_install:
 	dh_auto_install
 	$(RM) -rv $(DESTDIR)/usr/share/gocode
 
+	# Install our silent snippets to the Icecast web dir.
+	install -d -m 755 -o root -g root $(DESTDIR)/usr/share/icecast2/web
+	(for f in silence.ogg silence.mp3; do \
+	 install -m 644 -o root -g root $$f $(DESTDIR)/usr/share/icecast2/web/$$f; done)
+
 override_dh_installinit:
 	dh_installinit --name=autoradio
 

node/icecast/config.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"net/url"
 	"os"
+	"path/filepath"
 
 	"git.autistici.org/ale/autoradio"
 	pb "git.autistici.org/ale/autoradio/proto"
@@ -262,15 +263,26 @@ func slaveMountConfig(m *pb.Mount, masterAddr string) (*iceRelayConfig, error) {
 
 func masterMountConfig(m *pb.Mount) *iceMountConfig {
 	mc := iceMountConfig{
-		Name:     autoradio.MountPathToIcecastPath(m.Path),
-		Username: m.SourceUsername,
-		Password: m.SourcePassword,
+		Name:             autoradio.MountPathToIcecastPath(m.Path),
+		Username:         m.SourceUsername,
+		Password:         m.SourcePassword,
+		FallbackOverride: 1,
 		// MaxListeners: 1000,
 		// NoYp:   1,
 	}
-	if m.FallbackPath != "" {
+
+	// When no explicit fallback URL is specified, use the locally
+	// installed silence audo file. In order to serve the right
+	// format, we guess the file extension for the silence
+	// fallback by looking at the extension of the mount itself.
+	switch {
+	case m.FallbackPath != "":
 		mc.FallbackMount = m.FallbackPath
-		mc.FallbackOverride = 1
+	case filepath.Ext(m.Path) == ".ogg":
+		mc.FallbackMount = "/silence.ogg"
+	default:
+		mc.FallbackMount = "/silence.mp3"
 	}
+
 	return &mc
 }