channeldb: add new field to store the state hint obsfucator

channeldb/channel.go

@@ -144,7 +144,11 @@ type OpenChannel struct {
 	OurCommitTx  *wire.MsgTx
 	OurCommitSig []byte
 
-	// The outpoint of the final funding transaction.
+	// StateHintObsfucator are the btyes selected by the initiator (derived
+	// from their shachain root) to obsfucate the state-hint encoded within
+	// the commitment transaction.
+	StateHintObsfucator [4]byte
+
 	// ChanType denotes which type of channel this is.
 	ChanType ChannelType
 
@@ -1265,6 +1269,10 @@ func putChanElkremState(nodeChanBucket *bolt.Bucket, channel *OpenChannel) error
 		return err
 	}
 
+	if _, err := b.Write(channel.StateHintObsfucator[:]); err != nil {
+		return err
+	}
+
 	return nodeChanBucket.Put(elkremKey, b.Bytes())
 }
 
@@ -1320,6 +1328,11 @@ func fetchChanElkremState(nodeChanBucket *bolt.Bucket, channel *OpenChannel) err
 	}
 	channel.RemoteElkrem = remoteE
 
+	_, err = io.ReadFull(elkremStateBytes, channel.StateHintObsfucator[:])
+	if err != nil {
+		return err
+	}
+
 	return nil
 }
 

channeldb/channel_test.go

@@ -132,6 +132,9 @@ func createTestChannelState(cdb *DB) (*OpenChannel, error) {
 		}
 	}
 
+	var obsfucator [4]byte
+	copy(obsfucator[:], key[:])
+
 	return &OpenChannel{
 		IsInitiator:                true,
 		ChanType:                   SingleFunder,
@@ -147,6 +150,7 @@ func createTestChannelState(cdb *DB) (*OpenChannel, error) {
 		OurCommitSig:               bytes.Repeat([]byte{1}, 71),
 		LocalElkrem:                sender,
 		RemoteElkrem:               receiver,
+		StateHintObsfucator:        obsfucator,
 		FundingOutpoint:            testOutpoint,
 		OurMultiSigKey:             privKey.PubKey(),
 		TheirMultiSigKey:           privKey.PubKey(),
@@ -207,7 +211,8 @@ func TestOpenChannelPutGetDelete(t *testing.T) {
 		t.Fatalf("chan id's don't match")
 	}
 	if state.MinFeePerKb != newState.MinFeePerKb {
-		t.Fatalf("fee/kb doens't match")
+		t.Fatalf("fee/kb doesn't match")
+	}
 	if state.IsInitiator != newState.IsInitiator {
 		t.Fatalf("initiator status doesn't match")
 	}
@@ -322,6 +327,10 @@ func TestOpenChannelPutGetDelete(t *testing.T) {
 		t.Fatalf("htlcs don't match: %v vs %v", spew.Sdump(state.Htlcs[0]),
 			spew.Sdump(newState.Htlcs[0]))
 	}
+	if !bytes.Equal(state.StateHintObsfucator[:],
+		newState.StateHintObsfucator[:]) {
+		t.Fatalf("obsfuctators don't match")
+	}
 
 	// Finally to wrap up the test, delete the state of the channel within
 	// the database. This involves "closing" the channel which removes all