handshake proto + common handshake fixes

commonfile/fileproto/file_drpc.pb.go

@@ -1,5 +1,5 @@
 // Code generated by protoc-gen-go-drpc. DO NOT EDIT.
-// protoc-gen-go-drpc version: v0.0.32
+// protoc-gen-go-drpc version: v0.0.33
 // source: commonfile/fileproto/protos/file.proto
 
 package fileproto

commonspace/spacesyncproto/spacesync_drpc.pb.go

@@ -1,5 +1,5 @@
 // Code generated by protoc-gen-go-drpc. DO NOT EDIT.
-// protoc-gen-go-drpc version: v0.0.32
+// protoc-gen-go-drpc version: v0.0.33
 // source: commonspace/spacesyncproto/protos/spacesync.proto
 
 package spacesyncproto
@@ -102,6 +102,10 @@ type drpcSpaceSync_ObjectSyncStreamClient struct {
 	drpc.Stream
 }
 
+func (x *drpcSpaceSync_ObjectSyncStreamClient) GetStream() drpc.Stream {
+	return x.Stream
+}
+
 func (x *drpcSpaceSync_ObjectSyncStreamClient) Send(m *ObjectSyncMessage) error {
 	return x.MsgSend(m, drpcEncoding_File_commonspace_spacesyncproto_protos_spacesync_proto{})
 }

coordinator/coordinatorproto/coordinator_drpc.pb.go

@@ -1,5 +1,5 @@
 // Code generated by protoc-gen-go-drpc. DO NOT EDIT.
-// protoc-gen-go-drpc version: v0.0.32
+// protoc-gen-go-drpc version: v0.0.33
 // source: coordinator/coordinatorproto/protos/coordinator.proto
 
 package coordinatorproto

net/secureservice/handshake/credential.go

@@ -0,0 +1,125 @@
+package handshake
+
+import (
+	"context"
+	"github.com/anyproto/any-sync/net/secureservice/handshake/handshakeproto"
+	"github.com/libp2p/go-libp2p/core/sec"
+)
+
+func OutgoingHandshake(ctx context.Context, sc sec.SecureConn, cc CredentialChecker) (identity []byte, err error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	h := newHandshake()
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		identity, err = outgoingHandshake(h, sc, cc)
+	}()
+	select {
+	case <-done:
+		return
+	case <-ctx.Done():
+		_ = sc.Close()
+		return nil, ctx.Err()
+	}
+}
+
+func outgoingHandshake(h *handshake, sc sec.SecureConn, cc CredentialChecker) (identity []byte, err error) {
+	defer h.release()
+	h.conn = sc
+	localCred := cc.MakeCredentials(sc)
+	if err = h.writeCredentials(localCred); err != nil {
+		h.tryWriteErrAndClose(err)
+		return
+	}
+	msg, err := h.readMsg(msgTypeAck, msgTypeCred)
+	if err != nil {
+		h.tryWriteErrAndClose(err)
+		return
+	}
+	if msg.ack != nil {
+		if msg.ack.Error == handshakeproto.Error_InvalidCredentials {
+			return nil, ErrPeerDeclinedCredentials
+		}
+		return nil, HandshakeError{e: msg.ack.Error}
+	}
+
+	if identity, err = cc.CheckCredential(sc, msg.cred); err != nil {
+		h.tryWriteErrAndClose(err)
+		return
+	}
+
+	if err = h.writeAck(handshakeproto.Error_Null); err != nil {
+		h.tryWriteErrAndClose(err)
+		return nil, err
+	}
+
+	msg, err = h.readMsg(msgTypeAck)
+	if err != nil {
+		h.tryWriteErrAndClose(err)
+		return nil, err
+	}
+	if msg.ack.Error == handshakeproto.Error_Null {
+		return identity, nil
+	} else {
+		_ = h.conn.Close()
+		return nil, HandshakeError{e: msg.ack.Error}
+	}
+}
+
+func IncomingHandshake(ctx context.Context, sc sec.SecureConn, cc CredentialChecker) (identity []byte, err error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	h := newHandshake()
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		identity, err = incomingHandshake(h, sc, cc)
+	}()
+	select {
+	case <-done:
+		return
+	case <-ctx.Done():
+		_ = sc.Close()
+		return nil, ctx.Err()
+	}
+}
+
+func incomingHandshake(h *handshake, sc sec.SecureConn, cc CredentialChecker) (identity []byte, err error) {
+	defer h.release()
+	h.conn = sc
+
+	msg, err := h.readMsg(msgTypeCred)
+	if err != nil {
+		h.tryWriteErrAndClose(err)
+		return
+	}
+	if identity, err = cc.CheckCredential(sc, msg.cred); err != nil {
+		h.tryWriteErrAndClose(err)
+		return
+	}
+
+	if err = h.writeCredentials(cc.MakeCredentials(sc)); err != nil {
+		h.tryWriteErrAndClose(err)
+		return nil, err
+	}
+
+	msg, err = h.readMsg(msgTypeAck)
+	if err != nil {
+		h.tryWriteErrAndClose(err)
+		return nil, err
+	}
+	if msg.ack.Error != handshakeproto.Error_Null {
+		if msg.ack.Error == handshakeproto.Error_InvalidCredentials {
+			return nil, ErrPeerDeclinedCredentials
+		}
+		return nil, HandshakeError{e: msg.ack.Error}
+	}
+	if err = h.writeAck(handshakeproto.Error_Null); err != nil {
+		h.tryWriteErrAndClose(err)
+		return nil, err
+	}
+	return
+}

net/secureservice/handshake/credential_test.go

@@ -38,15 +38,14 @@ func TestOutgoingHandshake(t *testing.T) {
 		h := newHandshake()
 		h.conn = c2
 		// receive credential message
-		msg, err := h.readMsg()
+		msg, err := h.readMsg(msgTypeCred, msgTypeAck, msgTypeProto)
 		require.NoError(t, err)
-		require.Nil(t, msg.ack)
 		_, err = noVerifyChecker.CheckCredential(c2, msg.cred)
 		require.NoError(t, err)
 		// send credential message
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// receive ack
-		msg, err = h.readMsg()
+		msg, err = h.readMsg(msgTypeAck)
 		require.NoError(t, err)
 		require.Equal(t, handshakeproto.Error_Null, msg.ack.Error)
 		// send ack
@@ -76,7 +75,7 @@ func TestOutgoingHandshake(t *testing.T) {
 		h := newHandshake()
 		h.conn = c2
 		// receive credential message
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		_ = c2.Close()
 		res := <-handshakeResCh
@@ -92,7 +91,7 @@ func TestOutgoingHandshake(t *testing.T) {
 		h := newHandshake()
 		h.conn = c2
 		// receive credential message
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		require.NoError(t, h.writeAck(ErrInvalidCredentials.e))
 		res := <-handshakeResCh
@@ -108,10 +107,10 @@ func TestOutgoingHandshake(t *testing.T) {
 		h := newHandshake()
 		h.conn = c2
 		// receive credential message
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
-		msg, err := h.readMsg()
+		msg, err := h.readMsg(msgTypeAck)
 		require.NoError(t, err)
 		assert.Equal(t, ErrInvalidCredentials.e, msg.ack.Error)
 		res := <-handshakeResCh
@@ -127,7 +126,7 @@ func TestOutgoingHandshake(t *testing.T) {
 		h := newHandshake()
 		h.conn = c2
 		// receive credential message
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		// write credentials and close conn
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
@@ -145,12 +144,12 @@ func TestOutgoingHandshake(t *testing.T) {
 		h := newHandshake()
 		h.conn = c2
 		// receive credential message
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// read ack and close conn
-		_, err = h.readMsg()
+		_, err = h.readMsg(msgTypeAck)
 		require.NoError(t, err)
 		_ = c2.Close()
 		res := <-handshakeResCh
@@ -166,18 +165,17 @@ func TestOutgoingHandshake(t *testing.T) {
 		h := newHandshake()
 		h.conn = c2
 		// receive credential message
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// read ack
-		_, err = h.readMsg()
+		_, err = h.readMsg(msgTypeAck)
 		require.NoError(t, err)
 		// write cred instead ack
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
-		msg, err := h.readMsg()
+		_, err = h.readMsg(msgTypeAck)
-		require.NoError(t, err)
+		require.Error(t, err)
-		assert.Equal(t, handshakeproto.Error_UnexpectedPayload, msg.ack.Error)
 		res := <-handshakeResCh
 		require.Error(t, res.err)
 	})
@@ -191,7 +189,7 @@ func TestOutgoingHandshake(t *testing.T) {
 		h := newHandshake()
 		h.conn = c2
 		// receive credential message
-		msg, err := h.readMsg()
+		msg, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		require.Nil(t, msg.ack)
 		_, err = noVerifyChecker.CheckCredential(c2, msg.cred)
@@ -199,7 +197,7 @@ func TestOutgoingHandshake(t *testing.T) {
 		// send credential message
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// receive ack
-		msg, err = h.readMsg()
+		msg, err = h.readMsg(msgTypeAck)
 		require.NoError(t, err)
 		require.Equal(t, handshakeproto.Error_Null, msg.ack.Error)
 		// send ack
@@ -219,7 +217,7 @@ func TestOutgoingHandshake(t *testing.T) {
 		h := newHandshake()
 		h.conn = c2
 		// receive credential message
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		ctxCancel()
 		res := <-handshakeResCh
@@ -244,14 +242,14 @@ func TestIncomingHandshake(t *testing.T) {
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// wait credentials
-		msg, err := h.readMsg()
+		msg, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		require.Nil(t, msg.ack)
 		require.Equal(t, handshakeproto.CredentialsType_SkipVerify, msg.cred.Type)
 		// write ack
 		require.NoError(t, h.writeAck(handshakeproto.Error_Null))
 		// wait ack
-		msg, err = h.readMsg()
+		msg, err = h.readMsg(msgTypeAck)
 		require.NoError(t, err)
 		assert.Equal(t, handshakeproto.Error_Null, msg.ack.Error)
 		res := <-handshakeResCh
@@ -310,7 +308,7 @@ func TestIncomingHandshake(t *testing.T) {
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// except ack with error
-		msg, err := h.readMsg()
+		msg, err := h.readMsg(msgTypeAck)
 		require.NoError(t, err)
 		require.Nil(t, msg.cred)
 		require.Equal(t, handshakeproto.Error_InvalidCredentials, msg.ack.Error)
@@ -330,7 +328,7 @@ func TestIncomingHandshake(t *testing.T) {
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// except ack with error
-		msg, err := h.readMsg()
+		msg, err := h.readMsg(msgTypeAck)
 		require.NoError(t, err)
 		require.Nil(t, msg.cred)
 		require.Equal(t, handshakeproto.Error_IncompatibleVersion, msg.ack.Error)
@@ -350,13 +348,13 @@ func TestIncomingHandshake(t *testing.T) {
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// read cred
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		// write cred instead ack
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
-		// expect ack with error
+		// expect EOF
-		msg, err := h.readMsg()
+		_, err = h.readMsg(msgTypeAck)
-		require.Equal(t, handshakeproto.Error_UnexpectedPayload, msg.ack.Error)
+		require.Error(t, err)
 		res := <-handshakeResCh
 		require.Error(t, res.err)
 	})
@@ -372,7 +370,7 @@ func TestIncomingHandshake(t *testing.T) {
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// read cred and close conn
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		_ = c2.Close()
 
@@ -391,7 +389,7 @@ func TestIncomingHandshake(t *testing.T) {
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// wait credentials
-		msg, err := h.readMsg()
+		msg, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		require.Nil(t, msg.ack)
 		require.Equal(t, handshakeproto.CredentialsType_SkipVerify, msg.cred.Type)
@@ -413,7 +411,7 @@ func TestIncomingHandshake(t *testing.T) {
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// wait credentials
-		msg, err := h.readMsg()
+		msg, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		require.Nil(t, msg.ack)
 		require.Equal(t, handshakeproto.CredentialsType_SkipVerify, msg.cred.Type)
@@ -435,7 +433,7 @@ func TestIncomingHandshake(t *testing.T) {
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// wait credentials
-		msg, err := h.readMsg()
+		msg, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		require.Nil(t, msg.ack)
 		require.Equal(t, handshakeproto.CredentialsType_SkipVerify, msg.cred.Type)
@@ -458,7 +456,7 @@ func TestIncomingHandshake(t *testing.T) {
 		// write credentials
 		require.NoError(t, h.writeCredentials(noVerifyChecker.MakeCredentials(c2)))
 		// wait credentials
-		_, err := h.readMsg()
+		_, err := h.readMsg(msgTypeCred)
 		require.NoError(t, err)
 		ctxCancel()
 		res := <-handshakeResCh
@@ -482,7 +480,7 @@ func TestNotAHandshakeMessage(t *testing.T) {
 	_, err := c2.Write([]byte("some unexpected bytes"))
 	require.Error(t, err)
 	res := <-handshakeResCh
-	assert.EqualError(t, res.err, ErrGotNotAHandshakeMessage.Error())
+	assert.Error(t, res.err)
 }
 
 func TestEndToEnd(t *testing.T) {

net/secureservice/handshake/handshake.go

@@ -1,7 +1,6 @@
 package handshake
 
 import (
-	"context"
 	"encoding/binary"
 	"errors"
 	"github.com/anyproto/any-sync/net/secureservice/handshake/handshakeproto"
@@ -14,8 +13,17 @@ import (
 const headerSize = 5 // 1 byte for type + 4 byte for uint32 size
 
 const (
-	msgTypeCred = byte(1)
+	msgTypeCred  = byte(1)
-	msgTypeAck  = byte(2)
+	msgTypeAck   = byte(2)
+	msgTypeProto = byte(3)
+
+	sizeLimit = 200 * 1024 // 200 Kb
+)
+
+var (
+	credMsgTypes     = []byte{msgTypeCred, msgTypeAck}
+	protoMsgTypes    = []byte{msgTypeProto, msgTypeAck}
+	protoMsgTypesAck = []byte{msgTypeAck}
 )
 
 type HandshakeError struct {
@@ -38,17 +46,20 @@ var (
 	ErrSkipVerifyNotAllowed    = HandshakeError{e: handshakeproto.Error_SkipVerifyNotAllowed}
 	ErrUnexpected              = HandshakeError{e: handshakeproto.Error_Unexpected}
 
-	ErrIncompatibleVersion = HandshakeError{e: handshakeproto.Error_IncompatibleVersion}
+	ErrIncompatibleVersion     = HandshakeError{e: handshakeproto.Error_IncompatibleVersion}
+	ErrIncompatibleProto       = HandshakeError{e: handshakeproto.Error_IncompatibleProto}
+	ErrRemoteIncompatibleProto = HandshakeError{Err: errors.New("remote peer declined the proto")}
 
-	ErrGotNotAHandshakeMessage = errors.New("go not a handshake message")
+	ErrGotUnexpectedMessage = errors.New("go not a handshake message")
 )
 
 var handshakePool = &sync.Pool{New: func() any {
 	return &handshake{
-		remoteCred: &handshakeproto.Credentials{},
+		remoteCred:  &handshakeproto.Credentials{},
-		remoteAck:  &handshakeproto.Ack{},
+		remoteAck:   &handshakeproto.Ack{},
-		localAck:   &handshakeproto.Ack{},
+		localAck:    &handshakeproto.Ack{},
-		buf:        make([]byte, 0, 1024),
+		remoteProto: &handshakeproto.Proto{},
+		buf:         make([]byte, 0, 1024),
 	}
 }}
 
@@ -57,147 +68,17 @@ type CredentialChecker interface {
 	CheckCredential(sc sec.SecureConn, cred *handshakeproto.Credentials) (identity []byte, err error)
 }
 
-func OutgoingHandshake(ctx context.Context, sc sec.SecureConn, cc CredentialChecker) (identity []byte, err error) {
-	if ctx == nil {
-		ctx = context.Background()
-	}
-	h := newHandshake()
-	done := make(chan struct{})
-	go func() {
-		defer close(done)
-		identity, err = outgoingHandshake(h, sc, cc)
-	}()
-	select {
-	case <-done:
-		return
-	case <-ctx.Done():
-		_ = sc.Close()
-		return nil, ctx.Err()
-	}
-}
-
-func outgoingHandshake(h *handshake, sc sec.SecureConn, cc CredentialChecker) (identity []byte, err error) {
-	defer h.release()
-	h.conn = sc
-	localCred := cc.MakeCredentials(sc)
-	if err = h.writeCredentials(localCred); err != nil {
-		h.tryWriteErrAndClose(err)
-		return
-	}
-	msg, err := h.readMsg()
-	if err != nil {
-		h.tryWriteErrAndClose(err)
-		return
-	}
-	if msg.ack != nil {
-		if msg.ack.Error == handshakeproto.Error_InvalidCredentials {
-			return nil, ErrPeerDeclinedCredentials
-		}
-		return nil, HandshakeError{e: msg.ack.Error}
-	}
-
-	if identity, err = cc.CheckCredential(sc, msg.cred); err != nil {
-		h.tryWriteErrAndClose(err)
-		return
-	}
-
-	if err = h.writeAck(handshakeproto.Error_Null); err != nil {
-		h.tryWriteErrAndClose(err)
-		return nil, err
-	}
-
-	msg, err = h.readMsg()
-	if err != nil {
-		h.tryWriteErrAndClose(err)
-		return nil, err
-	}
-	if msg.ack == nil {
-		err = ErrUnexpectedPayload
-		h.tryWriteErrAndClose(err)
-		return nil, err
-	}
-	if msg.ack.Error == handshakeproto.Error_Null {
-		return identity, nil
-	} else {
-		_ = h.conn.Close()
-		return nil, HandshakeError{e: msg.ack.Error}
-	}
-}
-
-func IncomingHandshake(ctx context.Context, sc sec.SecureConn, cc CredentialChecker) (identity []byte, err error) {
-	if ctx == nil {
-		ctx = context.Background()
-	}
-	h := newHandshake()
-	done := make(chan struct{})
-	go func() {
-		defer close(done)
-		identity, err = incomingHandshake(h, sc, cc)
-	}()
-	select {
-	case <-done:
-		return
-	case <-ctx.Done():
-		_ = sc.Close()
-		return nil, ctx.Err()
-	}
-}
-
-func incomingHandshake(h *handshake, sc sec.SecureConn, cc CredentialChecker) (identity []byte, err error) {
-	defer h.release()
-	h.conn = sc
-
-	msg, err := h.readMsg()
-	if err != nil {
-		h.tryWriteErrAndClose(err)
-		return
-	}
-	if msg.ack != nil {
-		return nil, ErrUnexpectedPayload
-	}
-	if identity, err = cc.CheckCredential(sc, msg.cred); err != nil {
-		h.tryWriteErrAndClose(err)
-		return
-	}
-
-	if err = h.writeCredentials(cc.MakeCredentials(sc)); err != nil {
-		h.tryWriteErrAndClose(err)
-		return nil, err
-	}
-
-	msg, err = h.readMsg()
-	if err != nil {
-		h.tryWriteErrAndClose(err)
-		return nil, err
-	}
-	if msg.ack == nil {
-		err = ErrUnexpectedPayload
-		h.tryWriteErrAndClose(err)
-		return nil, err
-	}
-	if msg.ack.Error != handshakeproto.Error_Null {
-		if msg.ack.Error == handshakeproto.Error_InvalidCredentials {
-			return nil, ErrPeerDeclinedCredentials
-		}
-		return nil, HandshakeError{e: msg.ack.Error}
-	}
-	if err = h.writeAck(handshakeproto.Error_Null); err != nil {
-		h.tryWriteErrAndClose(err)
-		return nil, err
-	}
-	return
-}
-
 func newHandshake() *handshake {
 	return handshakePool.Get().(*handshake)
 }
 
 type handshake struct {
-	conn       sec.SecureConn
+	conn        sec.SecureConn
-	remoteCred *handshakeproto.Credentials
+	remoteCred  *handshakeproto.Credentials
-	remoteAck  *handshakeproto.Ack
+	remoteProto *handshakeproto.Proto
-	localAck   *handshakeproto.Ack
+	remoteAck   *handshakeproto.Ack
-	buf        []byte
+	localAck    *handshakeproto.Ack
+	buf         []byte
 }
 
 func (h *handshake) writeCredentials(cred *handshakeproto.Credentials) (err error) {
@@ -209,8 +90,17 @@ func (h *handshake) writeCredentials(cred *handshakeproto.Credentials) (err erro
 	return h.writeData(msgTypeCred, n)
 }
 
+func (h *handshake) writeProto(proto *handshakeproto.Proto) (err error) {
+	h.buf = slices.Grow(h.buf, proto.Size()+headerSize)[:proto.Size()+headerSize]
+	n, err := proto.MarshalToSizedBuffer(h.buf[headerSize:])
+	if err != nil {
+		return err
+	}
+	return h.writeData(msgTypeProto, n)
+}
+
 func (h *handshake) tryWriteErrAndClose(err error) {
-	if err == ErrGotNotAHandshakeMessage {
+	if err == ErrUnexpectedPayload {
 		// if we got unexpected message - just close the connection
 		_ = h.conn.Close()
 		return
@@ -243,21 +133,26 @@ func (h *handshake) writeData(tp byte, size int) (err error) {
 }
 
 type message struct {
-	cred *handshakeproto.Credentials
+	cred  *handshakeproto.Credentials
-	ack  *handshakeproto.Ack
+	proto *handshakeproto.Proto
+	ack   *handshakeproto.Ack
 }
 
-func (h *handshake) readMsg() (msg message, err error) {
+func (h *handshake) readMsg(allowedTypes ...byte) (msg message, err error) {
 	h.buf = slices.Grow(h.buf, headerSize)[:headerSize]
 	if _, err = io.ReadFull(h.conn, h.buf[:headerSize]); err != nil {
 		return
 	}
 	tp := h.buf[0]
-	if tp != msgTypeCred && tp != msgTypeAck {
+	if !slices.Contains(allowedTypes, tp) {
-		err = ErrGotNotAHandshakeMessage
+		err = ErrUnexpectedPayload
 		return
 	}
 	size := binary.LittleEndian.Uint32(h.buf[1:headerSize])
+	if size > sizeLimit {
+		err = ErrGotUnexpectedMessage
+		return
+	}
 	h.buf = slices.Grow(h.buf, int(size))[:size]
 	if _, err = io.ReadFull(h.conn, h.buf[:size]); err != nil {
 		return
@@ -273,6 +168,11 @@ func (h *handshake) readMsg() (msg message, err error) {
 			return
 		}
 		msg.ack = h.remoteAck
+	case msgTypeProto:
+		if err = h.remoteProto.Unmarshal(h.buf[:size]); err != nil {
+			return
+		}
+		msg.proto = h.remoteProto
 	}
 	return
 }
@@ -284,5 +184,6 @@ func (h *handshake) release() {
 	h.remoteAck.Error = 0
 	h.remoteCred.Type = 0
 	h.remoteCred.Payload = h.remoteCred.Payload[:0]
+	h.remoteProto.Proto = 0
 	handshakePool.Put(h)
 }

net/secureservice/handshake/handshakeproto/handshake.pb.go

@@ -59,6 +59,7 @@ const (
 	Error_SkipVerifyNotAllowed Error = 4
 	Error_DeadlineExceeded     Error = 5
 	Error_IncompatibleVersion  Error = 6
+	Error_IncompatibleProto    Error = 7
 )
 
 var Error_name = map[int32]string{
@@ -69,6 +70,7 @@ var Error_name = map[int32]string{
 	4: "SkipVerifyNotAllowed",
 	5: "DeadlineExceeded",
 	6: "IncompatibleVersion",
+	7: "IncompatibleProto",
 }
 
 var Error_value = map[string]int32{
@@ -79,6 +81,7 @@ var Error_value = map[string]int32{
 	"SkipVerifyNotAllowed": 4,
 	"DeadlineExceeded":     5,
 	"IncompatibleVersion":  6,
+	"IncompatibleProto":    7,
 }
 
 func (x Error) String() string {
@@ -89,6 +92,28 @@ func (Error) EnumDescriptor() ([]byte, []int) {
 	return fileDescriptor_60283fc75f020893, []int{1}
 }
 
+type ProtoType int32
+
+const (
+	ProtoType_DRPC ProtoType = 0
+)
+
+var ProtoType_name = map[int32]string{
+	0: "DRPC",
+}
+
+var ProtoType_value = map[string]int32{
+	"DRPC": 0,
+}
+
+func (x ProtoType) String() string {
+	return proto.EnumName(ProtoType_name, int32(x))
+}
+
+func (ProtoType) EnumDescriptor() ([]byte, []int) {
+	return fileDescriptor_60283fc75f020893, []int{2}
+}
+
 type Credentials struct {
 	Type    CredentialsType `protobuf:"varint,1,opt,name=type,proto3,enum=anyHandshake.CredentialsType" json:"type,omitempty"`
 	Payload []byte          `protobuf:"bytes,2,opt,name=payload,proto3" json:"payload,omitempty"`
@@ -247,12 +272,58 @@ func (m *Ack) GetError() Error {
 	return Error_Null
 }
 
+type Proto struct {
+	Proto ProtoType `protobuf:"varint,1,opt,name=proto,proto3,enum=anyHandshake.ProtoType" json:"proto,omitempty"`
+}
+
+func (m *Proto) Reset()         { *m = Proto{} }
+func (m *Proto) String() string { return proto.CompactTextString(m) }
+func (*Proto) ProtoMessage()    {}
+func (*Proto) Descriptor() ([]byte, []int) {
+	return fileDescriptor_60283fc75f020893, []int{3}
+}
+func (m *Proto) XXX_Unmarshal(b []byte) error {
+	return m.Unmarshal(b)
+}
+func (m *Proto) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	if deterministic {
+		return xxx_messageInfo_Proto.Marshal(b, m, deterministic)
+	} else {
+		b = b[:cap(b)]
+		n, err := m.MarshalToSizedBuffer(b)
+		if err != nil {
+			return nil, err
+		}
+		return b[:n], nil
+	}
+}
+func (m *Proto) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_Proto.Merge(m, src)
+}
+func (m *Proto) XXX_Size() int {
+	return m.Size()
+}
+func (m *Proto) XXX_DiscardUnknown() {
+	xxx_messageInfo_Proto.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_Proto proto.InternalMessageInfo
+
+func (m *Proto) GetProto() ProtoType {
+	if m != nil {
+		return m.Proto
+	}
+	return ProtoType_DRPC
+}
+
 func init() {
 	proto.RegisterEnum("anyHandshake.CredentialsType", CredentialsType_name, CredentialsType_value)
 	proto.RegisterEnum("anyHandshake.Error", Error_name, Error_value)
+	proto.RegisterEnum("anyHandshake.ProtoType", ProtoType_name, ProtoType_value)
 	proto.RegisterType((*Credentials)(nil), "anyHandshake.Credentials")
 	proto.RegisterType((*PayloadSignedPeerIds)(nil), "anyHandshake.PayloadSignedPeerIds")
 	proto.RegisterType((*Ack)(nil), "anyHandshake.Ack")
+	proto.RegisterType((*Proto)(nil), "anyHandshake.Proto")
 }
 
 func init() {
@@ -260,32 +331,35 @@ func init() {
 }
 
 var fileDescriptor_60283fc75f020893 = []byte{
-	// 395 bytes of a gzipped FileDescriptorProto
+	// 439 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x8c, 0x92, 0xcd, 0x6e, 0x13, 0x31,
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x8c, 0x92, 0xcf, 0x6e, 0xd3, 0x40,
-	0x10, 0xc7, 0xd7, 0x4d, 0x52, 0xaa, 0x21, 0x2d, 0xee, 0x34, 0xc0, 0x0a, 0x89, 0x55, 0x94, 0x53,
+	0x10, 0xc6, 0xbd, 0x4d, 0xdc, 0x96, 0x21, 0x2d, 0xdb, 0x6d, 0x4a, 0x2d, 0x24, 0xac, 0x28, 0xa7,
-	0xc8, 0x21, 0xe1, 0xeb, 0x05, 0x02, 0x2d, 0x22, 0x97, 0xaa, 0xda, 0x42, 0x0f, 0xdc, 0xdc, 0xf5,
+	0x10, 0x89, 0x84, 0x7f, 0xe2, 0x1e, 0x9a, 0x22, 0x72, 0xa9, 0x22, 0x17, 0x7a, 0xe0, 0xb6, 0xf5,
-	0xd0, 0x5a, 0x31, 0xf6, 0xca, 0x76, 0x43, 0xf7, 0x2d, 0xb8, 0xf2, 0x46, 0x1c, 0x7b, 0xe4, 0x88,
+	0x0e, 0xed, 0x2a, 0xcb, 0xda, 0xda, 0xdd, 0x86, 0xfa, 0x2d, 0x78, 0x14, 0x1e, 0x83, 0x63, 0x8f,
-	0x92, 0x17, 0x41, 0x71, 0x12, 0x92, 0x70, 0xea, 0xc5, 0x9e, 0x8f, 0x9f, 0xfd, 0xff, 0x8f, 0x65,
+	0x1c, 0x51, 0xf2, 0x22, 0xc8, 0x9b, 0xa4, 0x71, 0x38, 0xf5, 0x62, 0xef, 0xcc, 0xfc, 0xc6, 0xdf,
-	0x18, 0x1a, 0x0a, 0x03, 0x4f, 0xc5, 0x8d, 0x23, 0x4f, 0x6e, 0xa2, 0x0a, 0x1a, 0x5c, 0x0b, 0x23,
+	0x7c, 0xe3, 0x85, 0x81, 0x46, 0xd7, 0xb7, 0x98, 0xde, 0x18, 0xb4, 0x68, 0xa6, 0x32, 0xc5, 0xfe,
-	0xfd, 0xb5, 0x18, 0x6f, 0x44, 0xa5, 0xb3, 0xc1, 0x0e, 0xe2, 0xea, 0xd7, 0xd5, 0x7e, 0x2c, 0x60,
+	0x35, 0xd7, 0xc2, 0x5e, 0xf3, 0x49, 0xe5, 0x94, 0x9b, 0xcc, 0x65, 0x7d, 0xff, 0xb4, 0xeb, 0x6c,
-	0x53, 0x98, 0xea, 0xe3, 0xaa, 0xd6, 0x09, 0xf0, 0xf0, 0xbd, 0x23, 0x49, 0x26, 0x28, 0xa1, 0x3d,
+	0xcf, 0x27, 0x58, 0x83, 0xeb, 0xe2, 0xd3, 0x2a, 0xd7, 0x76, 0xf0, 0xf8, 0xc4, 0xa0, 0x40, 0xed,
-	0xbe, 0x82, 0x7a, 0xa8, 0x4a, 0x4a, 0x59, 0x9b, 0x75, 0x0f, 0x5e, 0x3f, 0xef, 0x6f, 0xb2, 0xfd,
+	0x24, 0x57, 0x96, 0xbd, 0x86, 0xba, 0x2b, 0x72, 0x8c, 0x48, 0x8b, 0x74, 0xf6, 0xdf, 0x3c, 0xef,
-	0x0d, 0xf0, 0x53, 0x55, 0x52, 0x1e, 0x51, 0x4c, 0xe1, 0x41, 0x29, 0x2a, 0x6d, 0x85, 0x4c, 0x77,
+	0x55, 0xd9, 0x5e, 0x05, 0xfc, 0x5c, 0xe4, 0x98, 0x78, 0x94, 0x45, 0xb0, 0x93, 0xf3, 0x42, 0x65,
-	0xda, 0xac, 0xdb, 0xcc, 0x57, 0xe9, 0xbc, 0x33, 0x21, 0xe7, 0x95, 0x35, 0x69, 0xad, 0xcd, 0xba,
+	0x5c, 0x44, 0x5b, 0x2d, 0xd2, 0x69, 0x24, 0xab, 0xb0, 0xac, 0x4c, 0xd1, 0x58, 0x99, 0xe9, 0xa8,
-	0xfb, 0xf9, 0x2a, 0xed, 0x7c, 0x80, 0xd6, 0xd9, 0x02, 0x3a, 0x57, 0x57, 0x86, 0xe4, 0x19, 0x91,
+	0xd6, 0x22, 0x9d, 0xbd, 0x64, 0x15, 0xb6, 0x3f, 0x42, 0x73, 0xbc, 0x80, 0xce, 0xe5, 0x95, 0x46,
-	0x1b, 0x49, 0x8f, 0xcf, 0x60, 0x4f, 0x45, 0x89, 0x50, 0x45, 0x0b, 0xcd, 0xfc, 0x5f, 0x8e, 0x08,
+	0x31, 0x46, 0x34, 0x23, 0x61, 0xd9, 0x33, 0xd8, 0x95, 0x5e, 0xc2, 0x15, 0x7e, 0x84, 0x46, 0x72,
-	0x75, 0xaf, 0xae, 0xcc, 0x52, 0x24, 0xc6, 0x9d, 0x97, 0x50, 0x1b, 0x16, 0x63, 0x7c, 0x01, 0x0d,
+	0x1f, 0x33, 0x06, 0x75, 0x2b, 0xaf, 0xf4, 0x52, 0xc4, 0x9f, 0xdb, 0xaf, 0xa0, 0x36, 0x48, 0x27,
-	0x72, 0xce, 0xba, 0xa5, 0xed, 0xa3, 0x6d, 0xdb, 0x27, 0xf3, 0x56, 0xbe, 0x20, 0x7a, 0x6f, 0xe1,
+	0xec, 0x05, 0x84, 0x68, 0x4c, 0x66, 0x96, 0x63, 0x1f, 0x6e, 0x8e, 0x7d, 0x5a, 0x96, 0x92, 0x05,
-	0xd1, 0x7f, 0x63, 0xe0, 0x01, 0xc0, 0xf9, 0x58, 0x95, 0x17, 0xe4, 0xd4, 0xd7, 0x8a, 0x27, 0x78,
+	0xd1, 0x7e, 0x0f, 0xe1, 0xd8, 0xaf, 0xe1, 0x25, 0x84, 0x7e, 0x1f, 0xcb, 0x9e, 0xe3, 0xcd, 0x1e,
-	0x08, 0xfb, 0x5b, 0xae, 0x38, 0xeb, 0xfd, 0x64, 0xd0, 0x88, 0xd7, 0xe0, 0x1e, 0xd4, 0x4f, 0x6f,
+	0xcf, 0x78, 0x93, 0x0b, 0xaa, 0xfb, 0x0e, 0x9e, 0xfc, 0x67, 0x9f, 0xed, 0x03, 0x9c, 0x4f, 0x64,
-	0xb4, 0xe6, 0xc9, 0xfc, 0xd8, 0x67, 0x43, 0xb7, 0x25, 0x15, 0x81, 0x24, 0x67, 0xf8, 0x04, 0x70,
+	0x7e, 0x81, 0x46, 0x7e, 0x2b, 0x68, 0xc0, 0x0e, 0x60, 0x6f, 0xc3, 0x0d, 0x25, 0xdd, 0x5f, 0x04,
-	0x64, 0x26, 0x42, 0x2b, 0xb9, 0x21, 0xc0, 0x77, 0xf0, 0x31, 0x1c, 0xae, 0xb9, 0xe5, 0xd4, 0xbc,
+	0x42, 0x2f, 0xcf, 0x76, 0xa1, 0x7e, 0x76, 0xa3, 0x14, 0x0d, 0xca, 0xb6, 0x2f, 0x1a, 0x6f, 0x73,
-	0x86, 0x29, 0xb4, 0xd6, 0xaa, 0xa7, 0x36, 0x0c, 0xb5, 0xb6, 0xdf, 0x49, 0xf2, 0x3a, 0xb6, 0x80,
+	0x4c, 0x1d, 0x0a, 0x4a, 0xd8, 0x53, 0x60, 0x23, 0x3d, 0xe5, 0x4a, 0x8a, 0x8a, 0x00, 0xdd, 0x62,
-	0x1f, 0x93, 0x90, 0x5a, 0x19, 0x3a, 0xb9, 0x2d, 0x88, 0x24, 0x49, 0xde, 0xc0, 0xa7, 0x70, 0x34,
+	0x47, 0x70, 0xb0, 0xe6, 0x96, 0xdb, 0xa2, 0x35, 0x16, 0x41, 0x73, 0xad, 0x7a, 0x96, 0xb9, 0x81,
-	0x32, 0x85, 0xfd, 0x56, 0x8a, 0xa0, 0x2e, 0x35, 0x5d, 0x2c, 0x5e, 0x92, 0xef, 0xbe, 0x3b, 0xfe,
+	0x52, 0xd9, 0x0f, 0x14, 0xb4, 0xce, 0x9a, 0x40, 0x87, 0xc8, 0x85, 0x92, 0x1a, 0x4f, 0x6f, 0x53,
-	0x35, 0xcd, 0xd8, 0xdd, 0x34, 0x63, 0x7f, 0xa6, 0x19, 0xfb, 0x31, 0xcb, 0x92, 0xbb, 0x59, 0x96,
+	0x44, 0x81, 0x82, 0x86, 0xec, 0x18, 0x0e, 0x47, 0x3a, 0xcd, 0xbe, 0xe7, 0xdc, 0xc9, 0x4b, 0x85,
-	0xfc, 0x9e, 0x65, 0xc9, 0x97, 0xde, 0xfd, 0x3f, 0xcb, 0xe5, 0x6e, 0xdc, 0xde, 0xfc, 0x0d, 0x00,
+	0x17, 0x8b, 0x3f, 0x40, 0xb7, 0xcb, 0xef, 0x57, 0x0b, 0xde, 0x31, 0xdd, 0xe9, 0x1e, 0xc1, 0xa3,
-	0x00, 0xff, 0xff, 0xbf, 0x78, 0x2f, 0x36, 0x61, 0x02, 0x00, 0x00,
+	0x7b, 0xf3, 0xe5, 0xd4, 0xc3, 0x64, 0x7c, 0x42, 0x83, 0x0f, 0xc3, 0xdf, 0xb3, 0x98, 0xdc, 0xcd,
+	0x62, 0xf2, 0x77, 0x16, 0x93, 0x9f, 0xf3, 0x38, 0xb8, 0x9b, 0xc7, 0xc1, 0x9f, 0x79, 0x1c, 0x7c,
+	0xed, 0x3e, 0xfc, 0x4a, 0x5e, 0x6e, 0xfb, 0xd7, 0xdb, 0x7f, 0x01, 0x00, 0x00, 0xff, 0xff, 0x53,
+	0x32, 0xf7, 0x79, 0xc7, 0x02, 0x00, 0x00,
 }
 
 func (m *Credentials) Marshal() (dAtA []byte, err error) {
@@ -393,6 +467,34 @@ func (m *Ack) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	return len(dAtA) - i, nil
 }
 
+func (m *Proto) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalToSizedBuffer(dAtA[:size])
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *Proto) MarshalTo(dAtA []byte) (int, error) {
+	size := m.Size()
+	return m.MarshalToSizedBuffer(dAtA[:size])
+}
+
+func (m *Proto) MarshalToSizedBuffer(dAtA []byte) (int, error) {
+	i := len(dAtA)
+	_ = i
+	var l int
+	_ = l
+	if m.Proto != 0 {
+		i = encodeVarintHandshake(dAtA, i, uint64(m.Proto))
+		i--
+		dAtA[i] = 0x8
+	}
+	return len(dAtA) - i, nil
+}
+
 func encodeVarintHandshake(dAtA []byte, offset int, v uint64) int {
 	offset -= sovHandshake(v)
 	base := offset
@@ -452,6 +554,18 @@ func (m *Ack) Size() (n int) {
 	return n
 }
 
+func (m *Proto) Size() (n int) {
+	if m == nil {
+		return 0
+	}
+	var l int
+	_ = l
+	if m.Proto != 0 {
+		n += 1 + sovHandshake(uint64(m.Proto))
+	}
+	return n
+}
+
 func sovHandshake(x uint64) (n int) {
 	return (math_bits.Len64(x|1) + 6) / 7
 }
@@ -767,6 +881,75 @@ func (m *Ack) Unmarshal(dAtA []byte) error {
 	}
 	return nil
 }
+func (m *Proto) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowHandshake
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= uint64(b&0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: Proto: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: Proto: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Proto", wireType)
+			}
+			m.Proto = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowHandshake
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.Proto |= ProtoType(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		default:
+			iNdEx = preIndex
+			skippy, err := skipHandshake(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if (skippy < 0) || (iNdEx+skippy) < 0 {
+				return ErrInvalidLengthHandshake
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
 func skipHandshake(dAtA []byte) (n int, err error) {
 	l := len(dAtA)
 	iNdEx := 0

net/secureservice/handshake/handshakeproto/protos/handshake.proto

@@ -5,6 +5,8 @@ option go_package = "net/secureservice/handshake/handshakeproto";
 
 /*
 
+CREDENTIALS HANDSHAKE
+
 Alice opens a new connection with Bob
 1. TLS handshake done successfully; both sides know local and remote peer identifiers.
 
@@ -68,4 +70,20 @@ enum Error {
     SkipVerifyNotAllowed = 4;
     DeadlineExceeded = 5;
     IncompatibleVersion = 6;
+    IncompatibleProto = 7;
+}
+
+
+/*
+
+PROTO HANDSHAKE
+
+ */
+
+message Proto {
+    ProtoType proto = 1;
+}
+
+enum ProtoType {
+    DRPC = 0;
 }

net/secureservice/handshake/proto.go

@@ -0,0 +1,97 @@
+package handshake
+
+import (
+	"context"
+	"github.com/anyproto/any-sync/net/secureservice/handshake/handshakeproto"
+	"github.com/libp2p/go-libp2p/core/sec"
+	"golang.org/x/exp/slices"
+)
+
+type ProtoChecker struct {
+	AllowedProtoTypes []handshakeproto.ProtoType
+}
+
+func OutgoingProtoHandshake(ctx context.Context, sc sec.SecureConn, pt handshakeproto.ProtoType) (err error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	h := newHandshake()
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		err = outgoingProtoHandshake(h, sc, pt)
+	}()
+	select {
+	case <-done:
+		return
+	case <-ctx.Done():
+		_ = sc.Close()
+		return ctx.Err()
+	}
+}
+
+func outgoingProtoHandshake(h *handshake, sc sec.SecureConn, pt handshakeproto.ProtoType) (err error) {
+	defer h.release()
+	h.conn = sc
+	localProto := &handshakeproto.Proto{
+		Proto: pt,
+	}
+	if err = h.writeProto(localProto); err != nil {
+		h.tryWriteErrAndClose(err)
+		return
+	}
+	msg, err := h.readMsg(msgTypeAck)
+	if err != nil {
+		h.tryWriteErrAndClose(err)
+		return
+	}
+	if msg.ack.Error == handshakeproto.Error_IncompatibleProto {
+		return ErrRemoteIncompatibleProto
+	}
+	if msg.ack.Error == handshakeproto.Error_Null {
+		return nil
+	}
+	return HandshakeError{e: msg.ack.Error}
+}
+
+func IncomingProtoHandshake(ctx context.Context, sc sec.SecureConn, pt ProtoChecker) (protoType handshakeproto.ProtoType, err error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	h := newHandshake()
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		protoType, err = incomingProtoHandshake(h, sc, pt)
+	}()
+	select {
+	case <-done:
+		return
+	case <-ctx.Done():
+		_ = sc.Close()
+		return 0, ctx.Err()
+	}
+}
+
+func incomingProtoHandshake(h *handshake, sc sec.SecureConn, pt ProtoChecker) (protoType handshakeproto.ProtoType, err error) {
+	defer h.release()
+	h.conn = sc
+
+	msg, err := h.readMsg(msgTypeProto)
+	if err != nil {
+		h.tryWriteErrAndClose(err)
+		return
+	}
+	if !slices.Contains(pt.AllowedProtoTypes, msg.proto.Proto) {
+		err = ErrIncompatibleProto
+		h.tryWriteErrAndClose(err)
+		return
+	}
+
+	if err = h.writeAck(handshakeproto.Error_Null); err != nil {
+		h.tryWriteErrAndClose(err)
+		return 0, err
+	} else {
+		return msg.proto.Proto, nil
+	}
+}

net/secureservice/handshake/proto_test.go

@@ -0,0 +1,121 @@
+package handshake
+
+import (
+	"github.com/anyproto/any-sync/net/secureservice/handshake/handshakeproto"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"testing"
+	"time"
+)
+
+type protoRes struct {
+	protoType handshakeproto.ProtoType
+	err       error
+}
+
+func newProtoChecker(types ...handshakeproto.ProtoType) ProtoChecker {
+	return ProtoChecker{AllowedProtoTypes: types}
+}
+func TestIncomingProtoHandshake(t *testing.T) {
+	t.Run("success", func(t *testing.T) {
+		c1, c2 := newConnPair(t)
+		var protoResCh = make(chan protoRes, 1)
+		go func() {
+			protoType, err := IncomingProtoHandshake(nil, c1, newProtoChecker(1))
+			protoResCh <- protoRes{protoType: protoType, err: err}
+		}()
+		h := newHandshake()
+		h.conn = c2
+
+		// write desired proto
+		require.NoError(t, h.writeProto(&handshakeproto.Proto{Proto: handshakeproto.ProtoType(1)}))
+		msg, err := h.readMsg(msgTypeAck)
+		require.NoError(t, err)
+		assert.Equal(t, handshakeproto.Error_Null, msg.ack.Error)
+		res := <-protoResCh
+		require.NoError(t, res.err)
+		assert.Equal(t, handshakeproto.ProtoType(1), res.protoType)
+	})
+	t.Run("incompatible", func(t *testing.T) {
+		c1, c2 := newConnPair(t)
+		var protoResCh = make(chan protoRes, 1)
+		go func() {
+			protoType, err := IncomingProtoHandshake(nil, c1, newProtoChecker(1))
+			protoResCh <- protoRes{protoType: protoType, err: err}
+		}()
+		h := newHandshake()
+		h.conn = c2
+
+		// write desired proto
+		require.NoError(t, h.writeProto(&handshakeproto.Proto{Proto: 0}))
+		msg, err := h.readMsg(msgTypeAck)
+		require.NoError(t, err)
+		assert.Equal(t, handshakeproto.Error_IncompatibleProto, msg.ack.Error)
+		res := <-protoResCh
+		require.Error(t, res.err, ErrIncompatibleProto.Error())
+	})
+}
+
+func TestOutgoingProtoHandshake(t *testing.T) {
+	t.Run("success", func(t *testing.T) {
+		c1, c2 := newConnPair(t)
+		var protoResCh = make(chan protoRes, 1)
+		go func() {
+			err := OutgoingProtoHandshake(nil, c1, 1)
+			protoResCh <- protoRes{err: err}
+		}()
+		h := newHandshake()
+		h.conn = c2
+
+		msg, err := h.readMsg(msgTypeProto)
+		require.NoError(t, err)
+		assert.Equal(t, handshakeproto.ProtoType(1), msg.proto.Proto)
+		require.NoError(t, h.writeAck(handshakeproto.Error_Null))
+
+		res := <-protoResCh
+		assert.NoError(t, res.err)
+	})
+	t.Run("incompatible", func(t *testing.T) {
+		c1, c2 := newConnPair(t)
+		var protoResCh = make(chan protoRes, 1)
+		go func() {
+			err := OutgoingProtoHandshake(nil, c1, 1)
+			protoResCh <- protoRes{err: err}
+		}()
+		h := newHandshake()
+		h.conn = c2
+
+		msg, err := h.readMsg(msgTypeProto)
+		require.NoError(t, err)
+		assert.Equal(t, handshakeproto.ProtoType(1), msg.proto.Proto)
+		require.NoError(t, h.writeAck(handshakeproto.Error_IncompatibleProto))
+
+		res := <-protoResCh
+		assert.EqualError(t, res.err, ErrRemoteIncompatibleProto.Error())
+	})
+}
+
+func TestEndToEndProto(t *testing.T) {
+	c1, c2 := newConnPair(t)
+	var (
+		inResCh  = make(chan protoRes, 1)
+		outResCh = make(chan protoRes, 1)
+	)
+	st := time.Now()
+	go func() {
+		err := OutgoingProtoHandshake(nil, c1, 0)
+		outResCh <- protoRes{err: err}
+	}()
+	go func() {
+		protoType, err := IncomingProtoHandshake(nil, c2, newProtoChecker(0, 1))
+		inResCh <- protoRes{protoType: protoType, err: err}
+	}()
+
+	outRes := <-outResCh
+	assert.NoError(t, outRes.err)
+
+	inRes := <-inResCh
+	assert.NoError(t, inRes.err)
+	assert.Equal(t, handshakeproto.ProtoType(0), inRes.protoType)
+	t.Log("dur", time.Since(st))
+}

net/streampool/testservice/testservice_drpc.pb.go

@@ -1,5 +1,5 @@
 // Code generated by protoc-gen-go-drpc. DO NOT EDIT.
-// protoc-gen-go-drpc version: v0.0.32
+// protoc-gen-go-drpc version: v0.0.33
 // source: net/streampool/testservice/protos/testservice.proto
 
 package testservice
@@ -72,6 +72,10 @@ type drpcTest_TestStreamClient struct {
 	drpc.Stream
 }
 
+func (x *drpcTest_TestStreamClient) GetStream() drpc.Stream {
+	return x.Stream
+}
+
 func (x *drpcTest_TestStreamClient) Send(m *StreamMessage) error {
 	return x.MsgSend(m, drpcEncoding_File_net_streampool_testservice_protos_testservice_proto{})
 }