add support for socks5 connector udp relay

connector/socks/v5/metadata.go

@@ -7,19 +7,32 @@ import (
 	mdx "github.com/go-gost/x/metadata"
 )
 
+const (
+	defaultUDPBufferSize = 4096
+)
+
 type metadata struct {
 	connectTimeout time.Duration
 	noTLS          bool
+	relay          string
+	udpBufferSize  int
 }
 
 func (c *socks5Connector) parseMetadata(md mdata.Metadata) (err error) {
 	const (
 		connectTimeout = "timeout"
 		noTLS          = "notls"
+		relay          = "relay"
+		udpBufferSize  = "udpBufferSize"
 	)
 
 	c.md.connectTimeout = mdx.GetDuration(md, connectTimeout)
 	c.md.noTLS = mdx.GetBool(md, noTLS)
+	c.md.relay = mdx.GetString(md, relay)
+	c.md.udpBufferSize = mdx.GetInt(md, udpBufferSize)
+	if c.md.udpBufferSize <= 0 {
+		c.md.udpBufferSize = defaultUDPBufferSize
+	}
 
 	return
 }