identify: make the protocol version configurable

config/config.go

@@ -64,6 +64,11 @@ type Config struct {
 	// Set it via the UserAgent option function.
 	UserAgent string
 
+	// ProtocolVersion is the protocol version that identifies the family
+	// of protocols used by the peer in the Identify protocol. It is set
+	// using the [ProtocolVersion] option.
+	ProtocolVersion string
+
 	PeerKey crypto.PrivKey
 
 	Transports         []TptC
@@ -223,6 +228,7 @@ func (cfg *Config) NewNode() (host.Host, error) {
 		NATManager:          cfg.NATManager,
 		EnablePing:          !cfg.DisablePing,
 		UserAgent:           cfg.UserAgent,
+		ProtocolVersion:     cfg.ProtocolVersion,
 		MultiaddrResolver:   cfg.MultiaddrResolver,
 		EnableHolePunching:  cfg.EnableHolePunching,
 		HolePunchingOptions: cfg.HolePunchingOptions,

options.go

@@ -414,6 +414,15 @@ var NoTransports = func(cfg *Config) error {
 	return nil
 }
 
+// ProtocolVersion sets the protocolVersion string required by the 
+// libp2p Identify protocol.
+func ProtocolVersion(s string) Option {
+	return func(cfg *Config) error {
+		cfg.ProtocolVersion = s
+		return nil
+	}
+}
+
 // UserAgent sets the libp2p user-agent sent along with the identify protocol
 func UserAgent(userAgent string) Option {
 	return func(cfg *Config) error {

p2p/host/basic/basic_host.go

@@ -145,6 +145,9 @@ type HostOpts struct {
 	// UserAgent sets the user-agent for the host.
 	UserAgent string
 
+	// ProtocolVersion sets the protocol version for the host.
+	ProtocolVersion string
+
 	// DisableSignedPeerRecord disables the generation of Signed Peer Records on this host.
 	DisableSignedPeerRecord bool
 
@@ -226,9 +229,18 @@ func NewHost(n network.Network, opts *HostOpts) (*BasicHost, error) {
 
 	// we can't set this as a default above because it depends on the *BasicHost.
 	if h.disableSignedPeerRecord {
-		h.ids, err = identify.NewIDService(h, identify.UserAgent(opts.UserAgent), identify.DisableSignedPeerRecord())
+		h.ids, err = identify.NewIDService(
+			h,
+			identify.UserAgent(opts.UserAgent),
+			identify.ProtocolVersion(opts.ProtocolVersion),
+			identify.DisableSignedPeerRecord(),
+		)
 	} else {
-		h.ids, err = identify.NewIDService(h, identify.UserAgent(opts.UserAgent))
+		h.ids, err = identify.NewIDService(
+			h,
+			identify.UserAgent(opts.UserAgent),
+			identify.ProtocolVersion(opts.ProtocolVersion),
+		)
 	}
 	if err != nil {
 		return nil, fmt.Errorf("failed to create Identify service: %s", err)

p2p/protocol/identify/id.go

@@ -33,11 +33,7 @@ var log = logging.Logger("net/identify")
 // service.
 const ID = "/ipfs/id/1.0.0"
 
-// LibP2PVersion holds the current protocol version for a client running this code
-// TODO(jbenet): fix the versioning mess.
-// XXX: Don't change this till 2020. You'll break all go-ipfs versions prior to
-// 0.4.17 which asserted an exact version match.
-const LibP2PVersion = "ipfs/0.1.0"
+const DefaultProtocolVersion = "ipfs/0.1.0"
 
 const ServiceName = "libp2p.identify"
 
@@ -89,8 +85,9 @@ type IDService interface {
 //   - Our IPFS Agent Version
 //   - Our public Listen Addresses
 type idService struct {
-	Host      host.Host
-	UserAgent string
+	Host            host.Host
+	UserAgent       string
+	ProtocolVersion string
 
 	ctx       context.Context
 	ctxCancel context.CancelFunc
@@ -135,9 +132,15 @@ func NewIDService(h host.Host, opts ...Option) (*idService, error) {
 		userAgent = cfg.userAgent
 	}
 
+	protocolVersion := DefaultProtocolVersion
+	if cfg.protocolVersion != "" {
+		protocolVersion = cfg.protocolVersion
+	}
+
 	s := &idService{
-		Host:      h,
-		UserAgent: userAgent,
+		Host:            h,
+		UserAgent:       userAgent,
+		ProtocolVersion: protocolVersion,
 
 		conns: make(map[network.Conn]chan struct{}),
 
@@ -188,8 +191,10 @@ func (ids *idService) loop() {
 	defer ids.refCount.Done()
 
 	phs := make(map[peer.ID]*peerHandler)
-	sub, err := ids.Host.EventBus().Subscribe([]interface{}{&event.EvtLocalProtocolsUpdated{},
-		&event.EvtLocalAddressesUpdated{}}, eventbus.BufSize(256))
+	sub, err := ids.Host.EventBus().Subscribe([]interface{}{
+		&event.EvtLocalProtocolsUpdated{},
+		&event.EvtLocalAddressesUpdated{},
+	}, eventbus.BufSize(256))
 	if err != nil {
 		log.Errorf("failed to subscribe to events on the bus, err=%s", err)
 		return
@@ -489,7 +494,6 @@ func (ids *idService) writeChunkedIdentifyMsg(c network.Conn, snapshot *identify
 	m := &pb.Identify{SignedPeerRecord: sr}
 	err := writer.WriteMsg(m)
 	return err
-
 }
 
 func (ids *idService) createBaseIdentifyResponse(
@@ -541,10 +545,8 @@ func (ids *idService) createBaseIdentifyResponse(
 	}
 
 	// set protocol versions
-	pv := LibP2PVersion
-	av := ids.UserAgent
-	mes.ProtocolVersion = &pv
-	mes.AgentVersion = &av
+	mes.ProtocolVersion = &ids.ProtocolVersion
+	mes.AgentVersion = &ids.UserAgent
 
 	return mes
 }

p2p/protocol/identify/id_test.go

@@ -75,7 +75,7 @@ func testHasProtocolVersions(t *testing.T, h host.Host, p peer.ID) {
 		t.Error("no protocol version")
 		return
 	}
-	if v.(string) != identify.LibP2PVersion {
+	if v.(string) != identify.DefaultProtocolVersion {
 		t.Error("protocol mismatch", err)
 	}
 	v, err = h.Peerstore().Get(p, "AgentVersion")

p2p/protocol/identify/opts.go

@@ -1,13 +1,22 @@
 package identify
 
 type config struct {
+	protocolVersion         string
 	userAgent               string
 	disableSignedPeerRecord bool
 }
 
 // Option is an option function for identify.
 type Option func(*config)
 
+// ProtocolVersion sets the protocol version string that will be used to
+// identify the family of protocols used by the peer.
+func ProtocolVersion(s string) Option {
+	return func(cfg *config) {
+		cfg.protocolVersion = s
+	}
+}
+
 // UserAgent sets the user agent this node will identify itself with to peers.
 func UserAgent(ua string) Option {
 	return func(cfg *config) {