.

go/neo/neonet/newlink.go

@@ -26,7 +26,6 @@ import (
 	"fmt"
 	"io"
 	"net"
-	"os"
 
 	"github.com/philhofer/fwd"
 	"github.com/tinylib/msgp/msgp"
@@ -38,6 +37,19 @@ import (
 	"lab.nexedi.com/kirr/neo/go/neo/proto"
 )
 
+// encTryOrder is the order of trials for encoding when establishing a NEO link from client side.
+//
+// NEO/go server autodetects client preferred encoding and adjusts to that, but
+// NEO/py rejects connections if client encoding does not exactly match server.
+//
+// To autodetect what NEO/py server uses DialLink retries dial + handshake with
+// client-preferred encodings in the following order.
+//
+// NOTE tests change this to verify that autodetection of NEO/py server
+// encoding actually works.
+var encTryOrder = []proto.Encoding{'N', 'M'}
+
+/*
 // encDefault is default encoding to use.
 // XXX we don't need this? (just set encDefault = 'M')
 var encDefault = proto.Encoding('N') // XXX = 'M' instead?
@@ -52,6 +64,7 @@ func init() {
 		os.Exit(1)
 	}
 }
+*/
 
 // ---- Handshake ----
 
@@ -60,7 +73,7 @@ func init() {
 // do not have such uses.
 
 func _HandshakeClient(ctx context.Context, conn net.Conn) (*NodeLink, error) {
-	return handshakeClient(ctx, conn, proto.Version, encDefault)
+	return handshakeClient(ctx, conn, proto.Version, encTryOrder[0])
 }
 
 func _HandshakeServer(ctx context.Context, conn net.Conn) (*NodeLink, error) {
@@ -291,10 +304,9 @@ func DialLink(ctx context.Context, net xnet.Networker, addr string) (*NodeLink,
 		return nil, err
 	}
 
-//	// TODO if handshake fails with "closed" (= might be unexpected encoding)
-//	//      -> try redial and handshaking with different encoding (= autodetect encoding)
-//	return _Handshake(ctx, peerConn, _LinkClient)
-	return handshakeClient(ctx, peerConn, proto.Version, encDefault)
+	// TODO if handshake fails with "closed" (= might be unexpected encoding)
+	//      -> try redial and handshaking with different encoding (= autodetect encoding)
+	return handshakeClient(ctx, peerConn, proto.Version, encTryOrder[0])
 }
 
 // ListenLink starts listening on laddr for incoming connections and wraps them as NodeLink.