add proxy protocol support for relay tunnel and rtcp

handler/forward/remote/metadata.go

@@ -11,16 +11,19 @@ type metadata struct {
 	readTimeout     time.Duration
 	sniffing        bool
 	sniffingTimeout time.Duration
+	proxyProtocol   int
 }
 
 func (h *forwardHandler) parseMetadata(md mdata.Metadata) (err error) {
 	const (
-		readTimeout = "readTimeout"
-		sniffing    = "sniffing"
+		readTimeout   = "readTimeout"
+		sniffing      = "sniffing"
+		proxyProtocol = "proxyProtocol"
 	)
 
 	h.md.readTimeout = mdutil.GetDuration(md, readTimeout)
 	h.md.sniffing = mdutil.GetBool(md, sniffing)
 	h.md.sniffingTimeout = mdutil.GetDuration(md, "sniffing.timeout")
+	h.md.proxyProtocol = mdutil.GetInt(md, proxyProtocol)
 	return
 }