allow optional data loss protect

Author: SWvheerden

src/ln/channel.rs

@@ -2275,6 +2275,20 @@ impl Channel {
 			return Err(ChannelError::Close("Peer sent a garbage channel_reestablish"));
 		}
 
+		//Check for dataloss fields and fail channel
+		if let Some(ref data_loss) = msg.data_loss_protect {
+			//check if provided signature is a valid signature from us
+			if chan_utils::build_commitment_secret(self.local_keys.commitment_seed, msg.next_remote_commitment_number-1) != data_loss.your_last_per_commitment_secret{
+				return Err(ChannelError::Close("Peer sent a garbage channel_reestablish with secret key not from us"));
+			}
+			//check if we have fallen beind
+			//We should not broadcast commitment transaction
+			if msg.next_remote_commitment_number > self.cur_local_commitment_transaction_number{
+				return Err(ChannelError::Close("We have fallen behind and we cannot catch up, need to close channel but not publish commitment"));
+			}
+			//TODO check dataloss.my_current_per_commitment_point
+		}
+
 		// Go ahead and unmark PeerDisconnected as various calls we may make check for it (and all
 		// remaining cases either succeed or ErrorMessage-fail).
 		self.channel_state &= !(ChannelState::PeerDisconnected as u32);