Fix channel_reestablish generation/handling around next_remote. 2018-11-reestablish-fix
authorMatt Corallo <git@bluematt.me>
Mon, 26 Nov 2018 23:31:51 +0000 (18:31 -0500)
committerMatt Corallo <git@bluematt.me>
Sun, 2 Dec 2018 22:26:16 +0000 (17:26 -0500)
src/ln/channel.rs
src/ln/channelmanager.rs

index 0ad0c0f52b90a667fdb9aedd5aecbc73d999bfe5..296d97c164ea967839fa2f6ec93ab66f215f56fe 100644 (file)
@@ -2289,7 +2289,8 @@ impl Channel {
                        return Err(ChannelError::Close("Peer sent a loose channel_reestablish not after reconnect"));
                }
 
-               if msg.next_local_commitment_number >= INITIAL_COMMITMENT_NUMBER || msg.next_remote_commitment_number >= INITIAL_COMMITMENT_NUMBER {
+               if msg.next_local_commitment_number >= INITIAL_COMMITMENT_NUMBER || msg.next_remote_commitment_number >= INITIAL_COMMITMENT_NUMBER ||
+                       msg.next_local_commitment_number == 0 {
                        return Err(ChannelError::Close("Peer sent a garbage channel_reestablish"));
                }
 
@@ -2304,15 +2305,15 @@ impl Channel {
                        })
                } else { None };
 
-               if self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::OurFundingLocked as u32) == ChannelState::FundingSent as u32 {
-                       // Short circuit the whole handler as there is nothing we can resend them
-                       return Ok((None, None, None, None, RAACommitmentOrder::CommitmentFirst, shutdown_msg));
-               }
-
-               if msg.next_local_commitment_number == 0 || msg.next_remote_commitment_number == 0 {
-                       if self.channel_state & (ChannelState::FundingSent as u32) != ChannelState::FundingSent as u32 {
-                               return Err(ChannelError::Close("Peer sent a pre-funding channel_reestablish after we exchanged funding_locked"));
+               if self.channel_state & (ChannelState::FundingSent as u32) == ChannelState::FundingSent as u32 {
+                       if self.channel_state & ChannelState::OurFundingLocked as u32 == 0 {
+                               if msg.next_remote_commitment_number != 0 {
+                                       return Err(ChannelError::Close("Peer claimed they saw a revoke_and_ack but we haven't sent funding_locked yet"));
+                               }
+                               // Short circuit the whole handler as there is nothing we can resend them
+                               return Ok((None, None, None, None, RAACommitmentOrder::CommitmentFirst, shutdown_msg));
                        }
+
                        // We have OurFundingLocked set!
                        let next_per_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
                        let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &next_per_commitment_secret);
@@ -2322,11 +2323,11 @@ impl Channel {
                        }), None, None, None, RAACommitmentOrder::CommitmentFirst, shutdown_msg));
                }
 
-               let required_revoke = if msg.next_remote_commitment_number == INITIAL_COMMITMENT_NUMBER - self.cur_local_commitment_transaction_number {
+               let required_revoke = if msg.next_remote_commitment_number + 1 == INITIAL_COMMITMENT_NUMBER - self.cur_local_commitment_transaction_number {
                        // Remote isn't waiting on any RevokeAndACK from us!
                        // Note that if we need to repeat our FundingLocked we'll do that in the next if block.
                        None
-               } else if msg.next_remote_commitment_number == (INITIAL_COMMITMENT_NUMBER - 1) - self.cur_local_commitment_transaction_number {
+               } else if msg.next_remote_commitment_number + 1 == (INITIAL_COMMITMENT_NUMBER - 1) - self.cur_local_commitment_transaction_number {
                        if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) != 0 {
                                self.monitor_pending_revoke_and_ack = true;
                                None
@@ -3053,11 +3054,27 @@ impl Channel {
        /// self.remove_uncommitted_htlcs_and_mark_paused()'d
        pub fn get_channel_reestablish(&self) -> msgs::ChannelReestablish {
                assert_eq!(self.channel_state & ChannelState::PeerDisconnected as u32, ChannelState::PeerDisconnected as u32);
+               assert_ne!(self.cur_remote_commitment_transaction_number, INITIAL_COMMITMENT_NUMBER);
                msgs::ChannelReestablish {
                        channel_id: self.channel_id(),
+                       // The protocol has two different commitment number concepts - the "commitment
+                       // transaction number", which starts from 0 and counts up, and the "revocation key
+                       // index" which starts at INITIAL_COMMITMENT_NUMBER and counts down. We track
+                       // commitment transaction numbers by the index which will be used to reveal the
+                       // revocation key for that commitment transaction, which means we have to convert them
+                       // to protocol-level commitment numbers here...
+
+                       // next_local_commitment_number is the next commitment_signed number we expect to
+                       // receive (indicating if they need to resend one that we missed).
                        next_local_commitment_number: INITIAL_COMMITMENT_NUMBER - self.cur_local_commitment_transaction_number,
-                       next_remote_commitment_number: INITIAL_COMMITMENT_NUMBER - self.cur_remote_commitment_transaction_number -
-                               if self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::OurFundingLocked as u32) == (ChannelState::FundingSent as u32) { 1 } else { 0 },
+                       // We have to set next_remote_commitment_number to the next revoke_and_ack we expect to
+                       // receive, however we track it by the next commitment number for a remote transaction
+                       // (which is one further, as they always revoke previous commitment transaction, not
+                       // the one we send) so we have to decrement by 1. Note that if
+                       // cur_remote_commitment_transaction_number is INITIAL_COMMITMENT_NUMBER we will have
+                       // dropped this channel on disconnect as it hasn't yet reached FundingSent so we can't
+                       // overflow here.
+                       next_remote_commitment_number: INITIAL_COMMITMENT_NUMBER - self.cur_remote_commitment_transaction_number - 1,
                        data_loss_protect: None,
                }
        }
index 2a2a40bce99c491895cbaabaeef8d2ae70e66624..a47236469719e181b9a33fce00e049502a858ae0 100644 (file)
@@ -6315,6 +6315,31 @@ mod tests {
                node_b.node.peer_connected(&node_a.node.get_our_node_id());
                let reestablish_2 = get_chan_reestablish_msgs!(node_b, node_a);
 
+               if send_funding_locked.0 {
+                       // If a expects a funding_locked, it better not think it has received a revoke_and_ack
+                       // from b
+                       for reestablish in reestablish_1.iter() {
+                               assert_eq!(reestablish.next_remote_commitment_number, 0);
+                       }
+               }
+               if send_funding_locked.1 {
+                       // If b expects a funding_locked, it better not think it has received a revoke_and_ack
+                       // from a
+                       for reestablish in reestablish_2.iter() {
+                               assert_eq!(reestablish.next_remote_commitment_number, 0);
+                       }
+               }
+               if send_funding_locked.0 || send_funding_locked.1 {
+                       // If we expect any funding_locked's, both sides better have set
+                       // next_local_commitment_number to 1
+                       for reestablish in reestablish_1.iter() {
+                               assert_eq!(reestablish.next_local_commitment_number, 1);
+                       }
+                       for reestablish in reestablish_2.iter() {
+                               assert_eq!(reestablish.next_local_commitment_number, 1);
+                       }
+               }
+
                let mut resp_1 = Vec::new();
                for msg in reestablish_1 {
                        node_b.node.handle_channel_reestablish(&node_a.node.get_our_node_id(), &msg).unwrap();