Configure protocolVersion for Identify protocol

Allows the protocolVersion field of the Idenfity protocol to be
configured on the host. The current value is fixed for what appears to
be for backwards compatibility with IPFS which makes it difficult for
non-IPFS protocols to use the library.

References:
  - libp2p#714
  - libp2p#1137
  - https://github.com/libp2p/rust-libp2p/blob/6855ab943bd7427a2135b46ad3d08f48fbf10872/protocols/identify/src/identify.rs#L125-L127

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.userAgent
+	}
+
 	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) {