Support receiving multiple funding_locked messages

As a part of adding SCID aliases to channels, we now have to accept
otherwise-redundant funding_locked messages which serve only to
update the SCID alias. Previously, we'd failt he channel as such
an update used to be bogus.

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 65f1be00008994242bf518e85bfc7527d21bf033..71e0ea121a929f2533c3af47714a50264e83b962 100644 (file)
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -2188,17 +2188,28 @@ impl<Signer: Sign> Channel<Signer> {
                } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::OurFundingLocked as u32) {
                        self.channel_state = ChannelState::ChannelFunded as u32 | (self.channel_state & MULTI_STATE_FLAGS);
                        self.update_time_counter += 1;
-               } else if (self.channel_state & (ChannelState::ChannelFunded as u32) != 0 &&
-                                // Note that funding_signed/funding_created will have decremented both by 1!
-                                self.cur_holder_commitment_transaction_number == INITIAL_COMMITMENT_NUMBER - 1 &&
-                                self.cur_counterparty_commitment_transaction_number == INITIAL_COMMITMENT_NUMBER - 1) ||
-                               // If we reconnected before sending our funding locked they may still resend theirs:
-                               (self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32) ==
-                                                     (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32)) {
-                       if self.counterparty_cur_commitment_point != Some(msg.next_per_commitment_point) {
+               } else if self.channel_state & (ChannelState::ChannelFunded as u32) != 0 ||
+                       // If we reconnected before sending our funding locked they may still resend theirs:
+                       (self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32) ==
+                                             (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32))
+               {
+                       // They probably disconnected/reconnected and re-sent the funding_locked, which is
+                       // required, or they're sending a fresh SCID alias.
+                       let expected_point =
+                               if self.cur_counterparty_commitment_transaction_number == INITIAL_COMMITMENT_NUMBER - 1 {
+                                       // If they haven't ever sent an updated point, the point they send should match
+                                       // the current one.
+                                       self.counterparty_cur_commitment_point
+                               } else {
+                                       // If they have sent updated points, funding_locked is always supposed to match
+                                       // their "first" point, which we re-derive here.
+                                       Some(PublicKey::from_secret_key(&self.secp_ctx, &SecretKey::from_slice(
+                                                       &self.commitment_secrets.get_secret(INITIAL_COMMITMENT_NUMBER - 1).expect("We should have all prev secrets available")
+                                               ).expect("We already advanced, so previous secret keys should have been validated already")))
+                               };
+                       if expected_point != Some(msg.next_per_commitment_point) {
                                return Err(ChannelError::Close("Peer sent a reconnect funding_locked with a different point".to_owned()));
                        }
-                       // They probably disconnected/reconnected and re-sent the funding_locked, which is required
                        return Ok(None);
                } else {
                        return Err(ChannelError::Close("Peer sent a funding_locked at a strange time".to_owned()));
@@ -4238,7 +4249,7 @@ impl<Signer: Sign> Channel<Signer> {
                self.outbound_scid_alias
        }
        /// Only allowed immediately after deserialization if get_outbound_scid_alias returns 0,
-       /// indicating we were written by an old LDK which did not set outbound SCID aliases.
+       /// indicating we were written by LDK prior to 0.0.106 which did not set outbound SCID aliases.
        pub fn set_outbound_scid_alias(&mut self, outbound_scid_alias: u64) {
                assert_eq!(self.outbound_scid_alias, 0);
                self.outbound_scid_alias = outbound_scid_alias;
@@ -4492,7 +4503,8 @@ impl<Signer: Sign> Channel<Signer> {
                if need_commitment_update {
                        if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) == 0 {
                                if self.channel_state & (ChannelState::PeerDisconnected as u32) == 0 {
-                                       let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+                                       let next_per_commitment_point =
+                                               self.holder_signer.get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 1, &self.secp_ctx);
                                        return Some(msgs::FundingLocked {
                                                channel_id: self.channel_id,
                                                next_per_commitment_point,

diff --git a/lightning/src/ln/priv_short_conf_tests.rs b/lightning/src/ln/priv_short_conf_tests.rs
index 4fadfc915d418b309ade9f603c82b0e10e1d71ae..a6f5a1b2ef7b8072a151deaeedb8bd27dd16f880 100644 (file)
--- a/lightning/src/ln/priv_short_conf_tests.rs
+++ b/lightning/src/ln/priv_short_conf_tests.rs
@@ -249,7 +249,7 @@ fn test_routed_scid_alias() {
        let mut nodes = create_network(3, &node_cfgs, &node_chanmgrs);
 
        create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 500_000_000, InitFeatures::known(), InitFeatures::known()).2;
-       create_unannounced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 500_000_000, InitFeatures::known(), InitFeatures::known());
+       let mut as_funding_locked = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 500_000_000, InitFeatures::known(), InitFeatures::known()).0;
 
        let last_hop = nodes[2].node.list_usable_channels();
        let hop_hints = vec![RouteHint(vec![RouteHintHop {
@@ -270,4 +270,17 @@ fn test_routed_scid_alias() {
 
        pass_along_route(&nodes[0], &[&[&nodes[1], &nodes[2]]], 100_000, payment_hash, payment_secret);
        claim_payment(&nodes[0], &[&nodes[1], &nodes[2]], payment_preimage);
+
+       // Now test that if a peer sends us a second funding_locked after the channel is operational we
+       // will use the new alias.
+       as_funding_locked.short_channel_id_alias = Some(0xdeadbeef);
+       nodes[2].node.handle_funding_locked(&nodes[1].node.get_our_node_id(), &as_funding_locked);
+       // Note that we always respond to a funding_locked with a channel_update. Not a lot of reason
+       // to bother updating that code, so just drop the message here.
+       get_event_msg!(nodes[2], MessageSendEvent::SendChannelUpdate, nodes[1].node.get_our_node_id());
+       let updated_channel_info = nodes[2].node.list_usable_channels();
+       assert_eq!(updated_channel_info.len(), 1);
+       assert_eq!(updated_channel_info[0].inbound_scid_alias.unwrap(), 0xdeadbeef);
+       // Note that because we never send a duplicate funding_locked we can't send a payment through
+       // the 0xdeadbeef SCID alias.
 }