From: Matt Corallo <git@bluematt.me>
Date: Thu, 2 Aug 2018 10:23:53 +0000 (-0400)
Subject: Fix panic on reorg through the funding_locked-generating block
X-Git-Tag: v0.0.12~354^2~3
X-Git-Url: http://git.bitcoin.ninja/?a=commitdiff_plain;h=a6161210e251ada6309f7bdeee560ed13ec15443;p=rust-lightning

Fix panic on reorg through the funding_locked-generating block

We had a TODO to handle "lost confirmation" in block_connected,
which we recently did in block_disconnected (calling force_shutdown
in case we get too many blocks disconnected) but didn't handle the
case where we had a simple reorg through the block that resulted in
us generating a funding_locked.
---

diff --git a/src/ln/channel.rs b/src/ln/channel.rs
index 43f913eb2..68a23dc67 100644
--- a/src/ln/channel.rs
+++ b/src/ln/channel.rs
@@ -1933,27 +1933,38 @@ impl Channel {
 				self.last_block_connected = header.bitcoin_hash();
 				self.funding_tx_confirmations += 1;
 				if self.funding_tx_confirmations == CONF_TARGET as u64 {
-					if non_shutdown_state == ChannelState::FundingSent as u32 {
+					let need_commitment_update = if non_shutdown_state == ChannelState::FundingSent as u32 {
 						self.channel_state |= ChannelState::OurFundingLocked as u32;
+						true
 					} else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32) {
 						self.channel_state = ChannelState::ChannelFunded as u32 | (self.channel_state & BOTH_SIDES_SHUTDOWN_MASK);
 						self.channel_update_count += 1;
-						//TODO: Something about a state where we "lost confirmation"
+						true
+					} else if self.channel_state == (ChannelState::FundingSent as u32 | ChannelState::OurFundingLocked as u32) {
+						// We got a reorg but not enough to trigger a force close, just update
+						// funding_tx_confirmed_in and return.
+						false
 					} else if self.channel_state < ChannelState::ChannelFunded as u32 {
-						panic!("Started confirming a channel in a state pre-FundingSent?");
-					}
+						panic!("Started confirming a channel in a state pre-FundingSent?: {}", self.channel_state);
+					} else {
+						// We got a reorg but not enough to trigger a force close, just update
+						// funding_tx_confirmed_in and return.
+						false
+					};
 					self.funding_tx_confirmed_in = Some(header.bitcoin_hash());
 
 					//TODO: Note that this must be a duplicate of the previous commitment point they sent us,
 					//as otherwise we will have a commitment transaction that they can't revoke (well, kinda,
 					//they can by sending two revoke_and_acks back-to-back, but not really). This appears to be
 					//a protocol oversight, but I assume I'm just missing something.
-					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).unwrap();
-					return Ok(Some(msgs::FundingLocked {
-						channel_id: self.channel_id,
-						next_per_commitment_point: next_per_commitment_point,
-					}));
+					if need_commitment_update {
+						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).unwrap();
+						return Ok(Some(msgs::FundingLocked {
+							channel_id: self.channel_id,
+							next_per_commitment_point: next_per_commitment_point,
+						}));
+					}
 				}
 			}
 		}