p2p/protocol/id: break on version mismatch.

TODOs:
- need to consolidate all the versioning stuff into one package
- need to do the version check as a handshake, before further
  communication happens. we used to do this.

protocol/identify/id.go

 package identify
 
 import (
-	"fmt"
+	"strings"
 	"sync"
 
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
@@ -24,16 +24,9 @@ var log = eventlog.Logger("net/identify")
 const ID protocol.ID = "/ipfs/identify"
 
 // IpfsVersion holds the current protocol version for a client running this code
-var IpfsVersion *semver.Version
-var ClientVersion = "go-ipfs/" + config.CurrentVersionNumber
-
-func init() {
-	var err error
-	IpfsVersion, err = semver.NewVersion("0.0.1")
-	if err != nil {
-		panic(fmt.Errorf("invalid protocol version: %v", err))
-	}
-}
+// TODO(jbenet): fix the versioning mess.
+const IpfsVersion = "ipfs/0.1.0"
+const ClientVersion = "go-ipfs/" + config.CurrentVersionNumber
 
 // IDService is a structure that implements ProtocolIdentify.
 // It is a trivial service that gives the other peer some
@@ -158,9 +151,10 @@ func (ids *IDService) populateMessage(mes *pb.Identify, c inet.Conn) {
 	log.Debugf("%s sent listen addrs to %s: %s", c.LocalPeer(), c.RemotePeer(), laddrs)
 
 	// set protocol versions
-	s := IpfsVersion.String()
-	mes.ProtocolVersion = &s
-	mes.AgentVersion = &ClientVersion
+	pv := IpfsVersion
+	av := ClientVersion
+	mes.ProtocolVersion = &pv
+	mes.AgentVersion = &av
 }
 
 func (ids *IDService) consumeMessage(mes *pb.Identify, c inet.Conn) {
@@ -192,6 +186,15 @@ func (ids *IDService) consumeMessage(mes *pb.Identify, c inet.Conn) {
 	// get protocol versions
 	pv := mes.GetProtocolVersion()
 	av := mes.GetAgentVersion()
+
+	// version check. if we shouldn't talk, bail.
+	// TODO: at this point, we've already exchanged information.
+	// move this into a first handshake before the connection can open streams.
+	if !protocolVersionsAreCompatible(pv, IpfsVersion) {
+		c.Close()
+		return
+	}
+
 	ids.Host.Peerstore().Put(p, "ProtocolVersion", pv)
 	ids.Host.Peerstore().Put(p, "AgentVersion", av)
 }
@@ -257,6 +260,31 @@ func addrInAddrs(a ma.Multiaddr, as []ma.Multiaddr) bool {
 	return false
 }
 
+// protocolVersionsAreCompatible checks that the two implementations
+// can talk to each other. It will use semver, but for now while
+// we're in tight development, we will return false for minor version
+// changes too.
+func protocolVersionsAreCompatible(v1, v2 string) bool {
+	if strings.HasPrefix(v1, "ipfs/") {
+		v1 = v1[5:]
+	}
+	if strings.HasPrefix(v2, "ipfs/") {
+		v2 = v2[5:]
+	}
+
+	v1s, err := semver.NewVersion(v1)
+	if err != nil {
+		return false
+	}
+
+	v2s, err := semver.NewVersion(v2)
+	if err != nil {
+		return false
+	}
+
+	return v1s.Major == v2s.Major && v1s.Minor == v2s.Minor
+}
+
 // netNotifiee defines methods to be used with the IpfsDHT
 type netNotifiee IDService
 

protocol/identify/id_test.go

@@ -79,7 +79,7 @@ func testHasProtocolVersions(t *testing.T, h host.Host, p peer.ID) {
 		t.Error("no protocol version")
 		return
 	}
-	if v.(string) != identify.IpfsVersion.String() {
+	if v.(string) != identify.IpfsVersion {
 		t.Error("protocol mismatch", err)
 	}
 	v, err = h.Peerstore().Get(p, "AgentVersion")