internal/mdns implementation

- Inspired from mdns_legacy
- Remove mdns dependency on libp2p
- Improve existing code to be safer and service oriented

Author: qdm12

dot/network/mdns.go

@@ -6,6 +6,7 @@ package network
 import (
 	"context"
 	"errors"
+	"fmt"
 	"math/big"
 	"strings"
 	"sync"
@@ -14,6 +15,7 @@ import (
 	"github.com/ChainSafe/gossamer/dot/peerset"
 	"github.com/ChainSafe/gossamer/dot/telemetry"
 	"github.com/ChainSafe/gossamer/internal/log"
+	"github.com/ChainSafe/gossamer/internal/mdns"
 	"github.com/ChainSafe/gossamer/internal/metrics"
 	"github.com/ChainSafe/gossamer/lib/common"
 	"github.com/ChainSafe/gossamer/lib/services"
@@ -105,7 +107,7 @@ type Service struct {
 
 	cfg           *Config
 	host          *host
-	mdns          *mdns
+	mdns          services.Service
 	gossip        *gossip
 	bufPool       *sync.Pool
 	streamManager *streamManager
@@ -188,12 +190,20 @@ func NewService(cfg *Config) (*Service, error) {
 		},
 	}
 
+	serviceTag := string(host.protocolID)
+	notifee := mdns.NewNotifeeTracker(host.p2pHost.Peerstore(), host.cm.peerSetHandler)
+	mdnsLogger := log.NewFromGlobal(log.AddContext("module", "mdns"))
+	mdnsLogger.Debugf(
+		"Creating mDNS discovery service with host %s and protocol %s...",
+		host.id(), host.protocolID)
+	mdnsService := mdns.NewService(host.p2pHost, serviceTag, mdnsLogger, notifee)
+
 	network := &Service{
 		ctx:                    ctx,
 		cancel:                 cancel,
 		cfg:                    cfg,
 		host:                   host,
-		mdns:                   newMDNS(host),
+		mdns:                   mdnsService,
 		gossip:                 newGossip(),
 		blockState:             cfg.BlockState,
 		transactionHandler:     cfg.TransactionHandler,
@@ -305,7 +315,10 @@ func (s *Service) Start() error {
 	s.startPeerSetHandler()
 
 	if !s.noMDNS {
-		s.mdns.start()
+		err = s.mdns.Start()
+		if err != nil {
+			return fmt.Errorf("starting mDNS service: %w", err)
+		}
 	}
 
 	if !s.noDiscover {
@@ -445,7 +458,7 @@ func (s *Service) Stop() error {
 	s.cancel()
 
 	// close mDNS discovery service
-	err := s.mdns.close()
+	err := s.mdns.Stop()
 	if err != nil {
 		logger.Errorf("Failed to close mDNS discovery service: %s", err)
 	}

dot/network/service.go

@@ -119,7 +119,6 @@ require (
 	github.com/libp2p/go-openssl v0.0.7 // indirect
 	github.com/libp2p/go-reuseport v0.2.0 // indirect
 	github.com/libp2p/go-yamux/v3 v3.1.2 // indirect
-	github.com/libp2p/zeroconf/v2 v2.1.1 // indirect
 	github.com/lucas-clemente/quic-go v0.27.1 // indirect
 	github.com/marten-seemann/qtls-go1-16 v0.1.5 // indirect
 	github.com/marten-seemann/qtls-go1-17 v0.1.1 // indirect
@@ -170,7 +169,7 @@ require (
 	github.com/tomasen/realip v0.0.0-20180522021738-f0c99a92ddce // indirect
 	github.com/vedhavyas/go-subkey v1.0.3 // indirect
 	github.com/whyrusleeping/go-keyspace v0.0.0-20160322163242-5b898ac5add1 // indirect
-	github.com/whyrusleeping/mdns v0.0.0-20190826153040-b9b60ed33aa9 // indirect
+	github.com/whyrusleeping/mdns v0.0.0-20190826153040-b9b60ed33aa9
 	github.com/whyrusleeping/multiaddr-filter v0.0.0-20160516205228-e903e4adabd7 // indirect
 	go.opencensus.io v0.23.0 // indirect
 	go.uber.org/atomic v1.9.0 // indirect

go.mod

@@ -711,7 +711,6 @@ github.com/libp2p/go-yamux/v3 v3.0.1/go.mod h1:s2LsDhHbh+RfCsQoICSYt58U2f8ijtPAN
 github.com/libp2p/go-yamux/v3 v3.0.2/go.mod h1:s2LsDhHbh+RfCsQoICSYt58U2f8ijtPANFD8BmE74Bo=
 github.com/libp2p/go-yamux/v3 v3.1.2 h1:lNEy28MBk1HavUAlzKgShp+F6mn/ea1nDYWftZhFW9Q=
 github.com/libp2p/go-yamux/v3 v3.1.2/go.mod h1:jeLEQgLXqE2YqX1ilAClIfCMDY+0uXQUKmmb/qp0gT4=
-github.com/libp2p/zeroconf/v2 v2.1.1 h1:XAuSczA96MYkVwH+LqqqCUZb2yH3krobMJ1YE+0hG2s=
 github.com/libp2p/zeroconf/v2 v2.1.1/go.mod h1:fuJqLnUwZTshS3U/bMRJ3+ow/v9oid1n0DmyYyNO1Xs=
 github.com/lightstep/lightstep-tracer-common/golang/gogo v0.0.0-20190605223551-bc2310a04743/go.mod h1:qklhhLq1aX+mtWk9cPHPzaBjWImj5ULL6C7HFJtXQMM=
 github.com/lightstep/lightstep-tracer-go v0.18.1/go.mod h1:jlF1pusYV4pidLvZ+XD0UBX0ZE6WURAspgAczcDHrL4=

go.sum

@@ -0,0 +1,59 @@
+// Copyright 2022 ChainSafe Systems (ON)
+// SPDX-License-Identifier: LGPL-3.0-only
+
+package mdns
+
+import (
+	"errors"
+	"fmt"
+	"net"
+
+	manet "github.com/multiformats/go-multiaddr/net"
+)
+
+var (
+	ErrTCPListenAddressNotFound = errors.New("TCP listen address not found")
+)
+
+func getMDNSIPsAndPort(p2pHost Networker) (ips []net.IP, port uint16, err error) {
+	tcpAddresses, err := getDialableListenAddrs(p2pHost)
+	if err != nil {
+		return nil, 0, fmt.Errorf("getting dialable listen addresses: %w", err)
+	}
+
+	ips = make([]net.IP, len(tcpAddresses))
+	for i := range tcpAddresses {
+		ips[i] = tcpAddresses[i].IP
+	}
+	port = uint16(tcpAddresses[0].Port)
+
+	return ips, port, nil
+}
+
+func getDialableListenAddrs(p2pHost Networker) (tcpAddresses []*net.TCPAddr, err error) {
+	multiAddresses, err := p2pHost.Network().InterfaceListenAddresses()
+	if err != nil {
+		return nil, fmt.Errorf("listing host interface listen addresses: %w", err)
+	}
+
+	tcpAddresses = make([]*net.TCPAddr, 0, len(multiAddresses))
+	for _, multiAddress := range multiAddresses {
+		netAddress, err := manet.ToNetAddr(multiAddress)
+		if err != nil {
+			continue
+		}
+
+		tcpAddress, ok := netAddress.(*net.TCPAddr)
+		if !ok {
+			continue
+		}
+
+		tcpAddresses = append(tcpAddresses, tcpAddress)
+	}
+
+	if len(tcpAddresses) == 0 {
+		return nil, fmt.Errorf("%w: in %d multiaddresses", ErrTCPListenAddressNotFound, len(multiAddresses))
+	}
+
+	return tcpAddresses, nil
+}

internal/mdns/dialable.go

@@ -0,0 +1,26 @@
+// Copyright 2022 ChainSafe Systems (ON)
+// SPDX-License-Identifier: LGPL-3.0-only
+
+package mdns
+
+import (
+	"github.com/libp2p/go-libp2p-core/network"
+	"github.com/libp2p/go-libp2p-core/peer"
+)
+
+// Logger is a logger interface for the mDNS service.
+type Logger interface {
+	Debugf(format string, args ...any)
+	Warnf(format string, args ...any)
+}
+
+// IDNetworker can return the peer ID and a network interface.
+type IDNetworker interface {
+	ID() peer.ID
+	Networker
+}
+
+// Networker can return a network interface.
+type Networker interface {
+	Network() network.Network
+}