Add backward compatibility for single bundle (#1355)

We change the protocol to accomodate publishing multiple bundles, in
order to propagate bundles for group chats and have a way to extend it
further.
This commit re-introduces backward compatibility for direct messages,
to be removed once that is not an issue anymore.

services/shhext/chat/protocol.go

@@ -24,7 +24,7 @@ func NewProtocolService(encryption *EncryptionService, addedBundlesHandler func(
 	}
 }
 
-func (p *ProtocolService) addBundleAndMarshal(myIdentityKey *ecdsa.PrivateKey, msg *ProtocolMessage) ([]byte, error) {
+func (p *ProtocolService) addBundleAndMarshal(myIdentityKey *ecdsa.PrivateKey, msg *ProtocolMessage, sendSingle bool) ([]byte, error) {
 	// Get a bundle
 	bundle, err := p.encryption.CreateBundle(myIdentityKey)
 	if err != nil {
@@ -32,7 +32,13 @@ func (p *ProtocolService) addBundleAndMarshal(myIdentityKey *ecdsa.PrivateKey, m
 		return nil, err
 	}
 
-	msg.Bundles = []*Bundle{bundle}
+	if sendSingle {
+		// DEPRECATED: This is only for backward compatibility, remove once not
+		// an issue anymore
+		msg.Bundle = bundle
+	} else {
+		msg.Bundles = []*Bundle{bundle}
+	}
 
 	// marshal for sending to wire
 	marshaledMessage, err := proto.Marshal(msg)
@@ -52,7 +58,7 @@ func (p *ProtocolService) BuildPublicMessage(myIdentityKey *ecdsa.PrivateKey, pa
 		PublicMessage:  payload,
 	}
 
-	return p.addBundleAndMarshal(myIdentityKey, protocolMessage)
+	return p.addBundleAndMarshal(myIdentityKey, protocolMessage, false)
 }
 
 // BuildDirectMessage marshals a 1:1 chat message given the user identity private key, the recipient's public key, and a payload
@@ -72,7 +78,7 @@ func (p *ProtocolService) BuildDirectMessage(myIdentityKey *ecdsa.PrivateKey, pa
 			DirectMessage:  encryptionResponse,
 		}
 
-		payload, err := p.addBundleAndMarshal(myIdentityKey, protocolMessage)
+		payload, err := p.addBundleAndMarshal(myIdentityKey, protocolMessage, true)
 		if err != nil {
 			return nil, err
 		}
@@ -99,7 +105,7 @@ func (p *ProtocolService) BuildPairingMessage(myIdentityKey *ecdsa.PrivateKey, p
 		DirectMessage:  encryptionResponse,
 	}
 
-	return p.addBundleAndMarshal(myIdentityKey, protocolMessage)
+	return p.addBundleAndMarshal(myIdentityKey, protocolMessage, true)
 }
 
 // ProcessPublicBundle processes a received X3DH bundle.

services/shhext/chat/protocol_test.go

@@ -44,6 +44,28 @@ func (s *ProtocolServiceTestSuite) SetupTest() {
 	s.bob = NewProtocolService(NewEncryptionService(bobPersistence, DefaultEncryptionServiceConfig("2")), addedBundlesHandler)
 }
 
+func (s *ProtocolServiceTestSuite) TestBuildPublicMessage() {
+	aliceKey, err := crypto.GenerateKey()
+	s.NoError(err)
+
+	payload, err := proto.Marshal(&ChatMessagePayload{
+		Content:     "Test content",
+		ClockValue:  1,
+		ContentType: "a",
+		MessageType: "some type",
+	})
+	s.NoError(err)
+
+	marshaledMsg, err := s.alice.BuildPublicMessage(aliceKey, payload)
+	s.NoError(err)
+	s.NotNil(marshaledMsg, "It creates a message")
+
+	unmarshaledMsg := &ProtocolMessage{}
+	err = proto.Unmarshal(marshaledMsg, unmarshaledMsg)
+	s.NoError(err)
+	s.NotNilf(unmarshaledMsg.GetBundles(), "It adds a bundle to the message")
+}
+
 func (s *ProtocolServiceTestSuite) TestBuildDirectMessage() {
 	bobKey, err := crypto.GenerateKey()
 	s.NoError(err)
@@ -59,24 +81,19 @@ func (s *ProtocolServiceTestSuite) TestBuildDirectMessage() {
 	s.NoError(err)
 
 	marshaledMsg, err := s.alice.BuildDirectMessage(aliceKey, payload, &bobKey.PublicKey, &aliceKey.PublicKey)
-
 	s.NoError(err)
 	s.NotNil(marshaledMsg, "It creates a message")
 	s.NotNil(marshaledMsg[&aliceKey.PublicKey], "It creates a single message")
 
 	unmarshaledMsg := &ProtocolMessage{}
 	err = proto.Unmarshal(marshaledMsg[&bobKey.PublicKey], unmarshaledMsg)
-
 	s.NoError(err)
-
+	s.NotNilf(unmarshaledMsg.GetBundle(), "It adds a bundle to the message")
-	s.NotNilf(unmarshaledMsg.GetBundles(), "It adds a bundle to the message")
 
 	directMessage := unmarshaledMsg.GetDirectMessage()
-
 	s.NotNilf(directMessage, "It sets the direct message")
 
 	encryptedPayload := directMessage["none"].GetPayload()
-
 	s.NotNilf(encryptedPayload, "It sets the payload of the message")
 
 	s.NotEqualf(payload, encryptedPayload, "It encrypts the payload")