Caplin: use sentinel default UDP address 0.0.0.0 (#13483)

Caplin's sentinel opens UDP port controlled by flag
`--caplin.discovery.port` we open it at `0.0.0.0` ignoring another flag
`--caplin.discovery.addr` which is `127.0.0.1`. TCP port opened
correctly with respect of `.addr`.

PR fixes default behavior.

cl/sentinel/sentinel.go

@@ -154,14 +154,11 @@ func (s *Sentinel) createListener() (*discover.UDPv5, error) {
 
 	var bindIP net.IP
 	var networkVersion string
-
 	// If the IP is an IPv4 address, bind to the correct zero address.
 	if ip.To4() != nil {
-		bindIP = net.IPv4zero
-		networkVersion = "udp4"
+		bindIP, networkVersion = ip.To4(), "udp4"
 	} else {
-		bindIP = net.IPv6zero
-		networkVersion = "udp6"
+		bindIP, networkVersion = ip.To16(), "udp6"
 	}
 
 	udpAddr := &net.UDPAddr{
@@ -179,11 +176,11 @@ func (s *Sentinel) createListener() (*discover.UDPv5, error) {
 	}
 
 	// Start stream handlers
-
 	net, err := discover.ListenV5(s.ctx, "any", conn, localNode, discCfg)
 	if err != nil {
 		return nil, err
 	}
+
 	handlers.NewConsensusHandlers(s.ctx, s.blockReader, s.indiciesDB, s.host, s.peers, s.cfg.NetworkConfig, localNode, s.cfg.BeaconConfig, s.ethClock, s.handshaker, s.forkChoiceReader, s.blobStorage, s.cfg.EnableBlocks).Start()
 
 	return net, err

cmd/utils/flags.go

@@ -823,7 +823,7 @@ var (
 	CaplinDiscoveryAddrFlag = cli.StringFlag{
 		Name:  "caplin.discovery.addr",
 		Usage: "Address for Caplin DISCV5 protocol",
-		Value: "127.0.0.1",
+		Value: "0.0.0.0",
 	}
 	CaplinDiscoveryPortFlag = cli.Uint64Flag{
 		Name:  "caplin.discovery.port",