Revert "XXX: BAD WIP"
[rust-lightning] / lightning / src / ln / channel.rs
index f3bf1ea2beb7efaa6d80cf8ab1486a8b55910823..76161f512b290dacd39a41b71b034141869079e2 100644 (file)
@@ -281,6 +281,26 @@ pub(super) enum ChannelUpdateStatus {
        Disabled,
 }
 
+/// We track when we sent an `AnnouncementSignatures` to our peer in a few states, described here.
+#[derive(PartialEq)]
+pub enum AnnouncementSigsState {
+       /// We have not sent our peer an `AnnouncementSignatures` yet, or our peer disconnected since
+       /// we sent the last `AnnouncementSignatures`.
+       NotSent,
+       /// We sent an `AnnouncementSignatures` to our peer since the last time our peer disconnected.
+       /// This state never appears on disk - instead we write `NotSent`.
+       MessageSent,
+       /// We sent a `CommitmentSigned` after the last `AnnouncementSignatures` we sent. Because we
+       /// only ever have a single `CommitmentSigned` pending at once, if we sent one after sending
+       /// `AnnouncementSignatures` then we know the peer received our `AnnouncementSignatures` if
+       /// they send back a `RevokeAndACK`.
+       /// This state never appears on disk - instead we write `NotSent`.
+       Committed,
+       /// We received a `RevokeAndACK`, effectively ack-ing our `AnnouncementSignatures`, at this
+       /// point we no longer need to re-send our `AnnouncementSignatures` again on reconnect.
+       PeerReceived,
+}
+
 /// An enum indicating whether the local or remote side offered a given HTLC.
 enum HTLCInitiator {
        LocalOffered,
@@ -374,6 +394,7 @@ pub(super) struct MonitorRestoreUpdates {
        pub finalized_claimed_htlcs: Vec<HTLCSource>,
        pub funding_broadcastable: Option<Transaction>,
        pub funding_locked: Option<msgs::FundingLocked>,
+       pub announcement_sigs: Option<msgs::AnnouncementSignatures>,
 }
 
 /// The return value of `channel_reestablish`
@@ -384,6 +405,7 @@ pub(super) struct ReestablishResponses {
        pub order: RAACommitmentOrder,
        pub mon_update: Option<ChannelMonitorUpdate>,
        pub holding_cell_failed_htlcs: Vec<(HTLCSource, PaymentHash)>,
+       pub announcement_sigs: Option<msgs::AnnouncementSignatures>,
        pub shutdown: Option<msgs::Shutdown>,
 }
 
@@ -441,6 +463,19 @@ pub(super) struct Channel<Signer: Sign> {
 
        channel_id: [u8; 32],
        channel_state: u32,
+
+       // When we reach max(6 blocks, minimum_depth), we need to send an AnnouncementSigs message to
+       // our peer. However, we want to make sure they received it, or else rebroadcast it when we
+       // next connect.
+       // We do so here, see `AnnouncementSigsSent` for more details on the state(s).
+       // Note that a number of our tests were written prior to the behavior here which retransmits
+       // AnnouncementSignatures until after an RAA completes, so the behavior is short-circuited in
+       // many tests.
+       #[cfg(any(test, feature = "_test_utils"))]
+       pub(crate) announcement_sigs_state: AnnouncementSigsState,
+       #[cfg(not(any(test, feature = "_test_utils")))]
+       announcement_sigs_state: AnnouncementSigsState,
+
        secp_ctx: Secp256k1<secp256k1::All>,
        channel_value_satoshis: u64,
 
@@ -620,6 +655,13 @@ pub(super) struct Channel<Signer: Sign> {
 
        /// This channel's type, as negotiated during channel open
        channel_type: ChannelTypeFeatures,
+
+       // Our counerparty can offer us SCID aliases which they will map to this channel when routing
+       // outbound payments. These can be used in invoice route hints to provide privacy of which
+       // on-chain transaction is ours.
+       // We only bother storing the most recent SCID alias at any time, though our counterparty has
+       // to store all of them.
+       latest_inbound_scid_alias: Option<u64>,
 }
 
 #[cfg(any(test, feature = "fuzztarget"))]
@@ -774,6 +816,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                        channel_id: keys_provider.get_secure_random_bytes(),
                        channel_state: ChannelState::OurInitSent as u32,
+                       announcement_sigs_state: AnnouncementSigsState::NotSent,
                        secp_ctx,
                        channel_value_satoshis,
 
@@ -864,6 +907,8 @@ impl<Signer: Sign> Channel<Signer> {
 
                        workaround_lnd_bug_4006: None,
 
+                       latest_inbound_scid_alias: None,
+
                        #[cfg(any(test, feature = "fuzztarget"))]
                        historical_inbound_htlc_fulfills: HashSet::new(),
 
@@ -1070,6 +1115,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                        channel_id: msg.temporary_channel_id,
                        channel_state: (ChannelState::OurInitSent as u32) | (ChannelState::TheirInitSent as u32),
+                       announcement_sigs_state: AnnouncementSigsState::NotSent,
                        secp_ctx,
 
                        latest_monitor_update_id: 0,
@@ -1163,6 +1209,8 @@ impl<Signer: Sign> Channel<Signer> {
 
                        workaround_lnd_bug_4006: None,
 
+                       latest_inbound_scid_alias: None,
+
                        #[cfg(any(test, feature = "fuzztarget"))]
                        historical_inbound_htlc_fulfills: HashSet::new(),
 
@@ -2022,12 +2070,24 @@ impl<Signer: Sign> Channel<Signer> {
                Ok((channel_monitor, self.funding_transaction.as_ref().cloned().unwrap()))
        }
 
-       pub fn funding_locked<L: Deref>(&mut self, msg: &msgs::FundingLocked, logger: &L) -> Result<(), ChannelError> where L::Target: Logger {
+       /// Handles a funding_locked message from our peer. If we've already sent our funding_locked
+       /// and the channel is now usable (and public), this may generate an announcement_signatures to
+       /// reply with.
+       pub fn funding_locked<L: Deref>(&mut self, msg: &msgs::FundingLocked, node_pk: PublicKey, genesis_block_hash: BlockHash, best_block: &BestBlock, logger: &L) -> Result<Option<msgs::AnnouncementSignatures>, ChannelError> where L::Target: Logger {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
                        self.workaround_lnd_bug_4006 = Some(msg.clone());
                        return Err(ChannelError::Ignore("Peer sent funding_locked when we needed a channel_reestablish. The peer is likely lnd, see https://github.com/lightningnetwork/lnd/issues/4006".to_owned()));
                }
 
+               if let Some(scid_alias) = msg.short_channel_id_alias {
+                       if Some(scid_alias.0) != self.short_channel_id {
+                               // The scid alias provided can be used to route payments *from* our counterparty,
+                               // i.e. can be used for inbound payments and provided in invoices, but is not used
+                               // whrn routing outbound payments.
+                               self.latest_inbound_scid_alias = Some(scid_alias.0);
+                       }
+               }
+
                let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
 
                if non_shutdown_state == ChannelState::FundingSent as u32 {
@@ -2035,18 +2095,36 @@ 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 we're getting 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.
+                                       self.commitment_secrets.get_secret(INITIAL_COMMITMENT_NUMBER - 1)
+                                               .map(|secret| SecretKey::from_slice(&secret).ok()).flatten()
+                                               .map(|sk| PublicKey::from_secret_key(&self.secp_ctx, &sk))
+                               };
+if self.commitment_secrets.get_secret(INITIAL_COMMITMENT_NUMBER - 1).is_some() {
+let cv = self.commitment_secrets.get_secret(INITIAL_COMMITMENT_NUMBER - 1)
+       .map(|secret| SecretKey::from_slice(&secret).ok()).flatten()
+       .map(|sk| PublicKey::from_secret_key(&self.secp_ctx, &sk));
+assert_eq!(cv, expected_point);
+panic!();
+}
+                       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(());
+                       return Ok(None);
                } else {
                        return Err(ChannelError::Close("Peer sent a funding_locked at a strange time".to_owned()));
                }
@@ -2056,7 +2134,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                log_info!(logger, "Received funding_locked from peer for channel {}", log_bytes!(self.channel_id()));
 
-               Ok(())
+               Ok(self.get_announcement_sigs(node_pk, genesis_block_hash, best_block.height(), logger))
        }
 
        /// Returns transaction if there is pending funding transaction that is yet to broadcast
@@ -2350,21 +2428,31 @@ impl<Signer: Sign> Channel<Signer> {
                res
        }
 
+       fn check_state_for_htlc_msg(&self) -> Result<(), ChannelError> {
+               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
+                       return Err(ChannelError::Close("Got HTLC message when channel was not in an operational state".to_owned()));
+               }
+               if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+                       return Err(ChannelError::Close("Peer sent HTLC message when we needed a channel_reestablish".to_owned()));
+               }
+               if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK == BOTH_SIDES_SHUTDOWN_MASK && self.last_sent_closing_fee.is_some() {
+                       return Err((None, ChannelError::Close("Peer sent HTLC message after we'd started exchanging closing_signeds".to_owned())));
+               }
+       }
+
        pub fn update_add_htlc<F, L: Deref>(&mut self, msg: &msgs::UpdateAddHTLC, mut pending_forward_status: PendingHTLCStatus, create_pending_htlc_status: F, logger: &L) -> Result<(), ChannelError>
        where F: for<'a> Fn(&'a Self, PendingHTLCStatus, u16) -> PendingHTLCStatus, L::Target: Logger {
                // We can't accept HTLCs sent after we've sent a shutdown.
-               let local_sent_shutdown = (self.channel_state & (ChannelState::ChannelFunded as u32 | ChannelState::LocalShutdownSent as u32)) != (ChannelState::ChannelFunded as u32);
+               let local_sent_shutdown = (self.channel_state & (ChannelState::LocalShutdownSent as u32)) != 0;
                if local_sent_shutdown {
                        pending_forward_status = create_pending_htlc_status(self, pending_forward_status, 0x4000|8);
                }
                // If the remote has sent a shutdown prior to adding this HTLC, then they are in violation of the spec.
-               let remote_sent_shutdown = (self.channel_state & (ChannelState::ChannelFunded as u32 | ChannelState::RemoteShutdownSent as u32)) != (ChannelState::ChannelFunded as u32);
+               let remote_sent_shutdown = (self.channel_state & (ChannelState::RemoteShutdownSent as u32)) != 0;
                if remote_sent_shutdown {
                        return Err(ChannelError::Close("Got add HTLC message when channel was not in an operational state".to_owned()));
                }
-               if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-                       return Err(ChannelError::Close("Peer sent update_add_htlc when we needed a channel_reestablish".to_owned()));
-               }
+               self.check_state_for_htlc_msg()?;
                if msg.amount_msat > self.channel_value_satoshis * 1000 {
                        return Err(ChannelError::Close("Remote side tried to send more than the total value of the channel".to_owned()));
                }
@@ -2524,37 +2612,19 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        pub fn update_fulfill_htlc(&mut self, msg: &msgs::UpdateFulfillHTLC) -> Result<(HTLCSource, u64), ChannelError> {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-                       return Err(ChannelError::Close("Got fulfill HTLC message when channel was not in an operational state".to_owned()));
-               }
-               if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-                       return Err(ChannelError::Close("Peer sent update_fulfill_htlc when we needed a channel_reestablish".to_owned()));
-               }
-
+               self.check_state_for_htlc_msg()?;
                let payment_hash = PaymentHash(Sha256::hash(&msg.payment_preimage.0[..]).into_inner());
                self.mark_outbound_htlc_removed(msg.htlc_id, Some(payment_hash), None).map(|htlc| (htlc.source.clone(), htlc.amount_msat))
        }
 
        pub fn update_fail_htlc(&mut self, msg: &msgs::UpdateFailHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-                       return Err(ChannelError::Close("Got fail HTLC message when channel was not in an operational state".to_owned()));
-               }
-               if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-                       return Err(ChannelError::Close("Peer sent update_fail_htlc when we needed a channel_reestablish".to_owned()));
-               }
-
+               self.check_state_for_htlc_msg()?;
                self.mark_outbound_htlc_removed(msg.htlc_id, None, Some(fail_reason))?;
                Ok(())
        }
 
        pub fn update_fail_malformed_htlc(&mut self, msg: &msgs::UpdateFailMalformedHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-                       return Err(ChannelError::Close("Got fail malformed HTLC message when channel was not in an operational state".to_owned()));
-               }
-               if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-                       return Err(ChannelError::Close("Peer sent update_fail_malformed_htlc when we needed a channel_reestablish".to_owned()));
-               }
-
+               self.check_state_for_htlc_msg()?;
                self.mark_outbound_htlc_removed(msg.htlc_id, None, Some(fail_reason))?;
                Ok(())
        }
@@ -2562,15 +2632,7 @@ impl<Signer: Sign> Channel<Signer> {
        pub fn commitment_signed<L: Deref>(&mut self, msg: &msgs::CommitmentSigned, logger: &L) -> Result<(msgs::RevokeAndACK, Option<msgs::CommitmentSigned>, ChannelMonitorUpdate), (Option<ChannelMonitorUpdate>, ChannelError)>
                where L::Target: Logger
        {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-                       return Err((None, ChannelError::Close("Got commitment signed message when channel was not in an operational state".to_owned())));
-               }
-               if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-                       return Err((None, ChannelError::Close("Peer sent commitment_signed when we needed a channel_reestablish".to_owned())));
-               }
-               if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK == BOTH_SIDES_SHUTDOWN_MASK && self.last_sent_closing_fee.is_some() {
-                       return Err((None, ChannelError::Close("Peer sent commitment_signed after we'd started exchanging closing_signeds".to_owned())));
-               }
+               self.check_state_for_htlc_msg()?;
 
                let funding_script = self.get_funding_redeemscript();
 
@@ -2881,15 +2943,7 @@ impl<Signer: Sign> Channel<Signer> {
        pub fn revoke_and_ack<L: Deref>(&mut self, msg: &msgs::RevokeAndACK, logger: &L) -> Result<RAAUpdates, ChannelError>
                where L::Target: Logger,
        {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-                       return Err(ChannelError::Close("Got revoke/ACK message when channel was not in an operational state".to_owned()));
-               }
-               if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-                       return Err(ChannelError::Close("Peer sent revoke_and_ack when we needed a channel_reestablish".to_owned()));
-               }
-               if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK == BOTH_SIDES_SHUTDOWN_MASK && self.last_sent_closing_fee.is_some() {
-                       return Err(ChannelError::Close("Peer sent revoke_and_ack after we'd started exchanging closing_signeds".to_owned()));
-               }
+               self.check_state_for_htlc_msg()?;
 
                let secret = secp_check!(SecretKey::from_slice(&msg.per_commitment_secret), "Peer provided an invalid per_commitment_secret".to_owned());
 
@@ -2941,6 +2995,10 @@ impl<Signer: Sign> Channel<Signer> {
                self.counterparty_cur_commitment_point = Some(msg.next_per_commitment_point);
                self.cur_counterparty_commitment_transaction_number -= 1;
 
+               if self.announcement_sigs_state == AnnouncementSigsState::Committed {
+                       self.announcement_sigs_state = AnnouncementSigsState::PeerReceived;
+               }
+
                log_trace!(logger, "Updating HTLCs on receipt of RAA in channel {}...", log_bytes!(self.channel_id()));
                let mut to_forward_infos = Vec::new();
                let mut revoked_htlcs = Vec::new();
@@ -3216,6 +3274,11 @@ impl<Signer: Sign> Channel<Signer> {
                        self.channel_state = ChannelState::ShutdownComplete as u32;
                        return;
                }
+
+               if self.announcement_sigs_state == AnnouncementSigsState::MessageSent || self.announcement_sigs_state == AnnouncementSigsState::Committed {
+                       self.announcement_sigs_state = AnnouncementSigsState::NotSent;
+               }
+
                // Upon reconnect we have to start the closing_signed dance over, but shutdown messages
                // will be retransmitted.
                self.last_sent_closing_fee = None;
@@ -3292,7 +3355,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// Indicates that the latest ChannelMonitor update has been committed by the client
        /// successfully and we should restore normal operation. Returns messages which should be sent
        /// to the remote side.
-       pub fn monitor_updating_restored<L: Deref>(&mut self, logger: &L) -> MonitorRestoreUpdates where L::Target: Logger {
+       pub fn monitor_updating_restored<L: Deref>(&mut self, logger: &L, node_pk: PublicKey, genesis_block_hash: BlockHash, best_block_height: u32) -> MonitorRestoreUpdates where L::Target: Logger {
                assert_eq!(self.channel_state & ChannelState::MonitorUpdateFailed as u32, ChannelState::MonitorUpdateFailed as u32);
                self.channel_state &= !(ChannelState::MonitorUpdateFailed as u32);
 
@@ -3312,9 +3375,12 @@ impl<Signer: Sign> Channel<Signer> {
                        Some(msgs::FundingLocked {
                                channel_id: self.channel_id(),
                                next_per_commitment_point,
+                               short_channel_id_alias: None,
                        })
                } else { None };
 
+               let announcement_sigs = self.get_announcement_sigs(node_pk, genesis_block_hash, best_block_height, logger);
+
                let mut accepted_htlcs = Vec::new();
                mem::swap(&mut accepted_htlcs, &mut self.monitor_pending_forwards);
                let mut failed_htlcs = Vec::new();
@@ -3327,7 +3393,7 @@ impl<Signer: Sign> Channel<Signer> {
                        self.monitor_pending_commitment_signed = false;
                        return MonitorRestoreUpdates {
                                raa: None, commitment_update: None, order: RAACommitmentOrder::RevokeAndACKFirst,
-                               accepted_htlcs, failed_htlcs, finalized_claimed_htlcs, funding_broadcastable, funding_locked
+                               accepted_htlcs, failed_htlcs, finalized_claimed_htlcs, funding_broadcastable, funding_locked, announcement_sigs
                        };
                }
 
@@ -3346,7 +3412,7 @@ impl<Signer: Sign> Channel<Signer> {
                        if commitment_update.is_some() { "a" } else { "no" }, if raa.is_some() { "an" } else { "no" },
                        match order { RAACommitmentOrder::CommitmentFirst => "commitment", RAACommitmentOrder::RevokeAndACKFirst => "RAA"});
                MonitorRestoreUpdates {
-                       raa, commitment_update, order, accepted_htlcs, failed_htlcs, finalized_claimed_htlcs, funding_broadcastable, funding_locked
+                       raa, commitment_update, order, accepted_htlcs, failed_htlcs, finalized_claimed_htlcs, funding_broadcastable, funding_locked, announcement_sigs
                }
        }
 
@@ -3460,7 +3526,9 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// May panic if some calls other than message-handling calls (which will all Err immediately)
        /// have been called between remove_uncommitted_htlcs_and_mark_paused and this call.
-       pub fn channel_reestablish<L: Deref>(&mut self, msg: &msgs::ChannelReestablish, logger: &L) -> Result<ReestablishResponses, ChannelError> where L::Target: Logger {
+       pub fn channel_reestablish<L: Deref>(&mut self, msg: &msgs::ChannelReestablish, logger: &L,
+               node_pk: PublicKey, genesis_block_hash: BlockHash, best_block: &BestBlock)
+       -> Result<ReestablishResponses, ChannelError> where L::Target: Logger {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == 0 {
                        // While BOLT 2 doesn't indicate explicitly we should error this channel here, it
                        // almost certainly indicates we are going to end up out-of-sync in some way, so we
@@ -3504,6 +3572,8 @@ impl<Signer: Sign> Channel<Signer> {
                        })
                } else { None };
 
+               let announcement_sigs = self.get_announcement_sigs(node_pk, genesis_block_hash, best_block.height(), logger);
+
                if self.channel_state & (ChannelState::FundingSent as u32) == ChannelState::FundingSent as u32 {
                        // If we're waiting on a monitor update, we shouldn't re-send any funding_locked's.
                        if self.channel_state & (ChannelState::OurFundingLocked as u32) == 0 ||
@@ -3517,21 +3587,25 @@ impl<Signer: Sign> Channel<Signer> {
                                        raa: None, commitment_update: None, mon_update: None,
                                        order: RAACommitmentOrder::CommitmentFirst,
                                        holding_cell_failed_htlcs: Vec::new(),
-                                       shutdown
+                                       shutdown, announcement_sigs,
                                });
                        }
 
                        // We have OurFundingLocked set!
                        let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+// XXX: We need to figure out exactly what format the FundingLocked should take if the channel has
+// moved forward already due to receiving payments prior to the funding locking in.
+// This needs spec discussion.
                        return Ok(ReestablishResponses {
                                funding_locked: Some(msgs::FundingLocked {
                                        channel_id: self.channel_id(),
                                        next_per_commitment_point,
+                                       short_channel_id_alias: None,
                                }),
                                raa: None, commitment_update: None, mon_update: None,
                                order: RAACommitmentOrder::CommitmentFirst,
                                holding_cell_failed_htlcs: Vec::new(),
-                               shutdown
+                               shutdown, announcement_sigs,
                        });
                }
 
@@ -3562,6 +3636,7 @@ impl<Signer: Sign> Channel<Signer> {
                        Some(msgs::FundingLocked {
                                channel_id: self.channel_id(),
                                next_per_commitment_point,
+                               short_channel_id_alias: None,
                        })
                } else { None };
 
@@ -3583,7 +3658,7 @@ impl<Signer: Sign> Channel<Signer> {
                                                panic!("Got non-channel-failing result from free_holding_cell_htlcs"),
                                        Ok((Some((commitment_update, monitor_update)), holding_cell_failed_htlcs)) => {
                                                Ok(ReestablishResponses {
-                                                       funding_locked, shutdown,
+                                                       funding_locked, shutdown, announcement_sigs,
                                                        raa: required_revoke,
                                                        commitment_update: Some(commitment_update),
                                                        order: self.resend_order.clone(),
@@ -3593,7 +3668,7 @@ impl<Signer: Sign> Channel<Signer> {
                                        },
                                        Ok((None, holding_cell_failed_htlcs)) => {
                                                Ok(ReestablishResponses {
-                                                       funding_locked, shutdown,
+                                                       funding_locked, shutdown, announcement_sigs,
                                                        raa: required_revoke,
                                                        commitment_update: None,
                                                        order: self.resend_order.clone(),
@@ -3604,7 +3679,7 @@ impl<Signer: Sign> Channel<Signer> {
                                }
                        } else {
                                Ok(ReestablishResponses {
-                                       funding_locked, shutdown,
+                                       funding_locked, shutdown, announcement_sigs,
                                        raa: required_revoke,
                                        commitment_update: None,
                                        order: self.resend_order.clone(),
@@ -3622,14 +3697,14 @@ impl<Signer: Sign> Channel<Signer> {
                        if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) != 0 {
                                self.monitor_pending_commitment_signed = true;
                                Ok(ReestablishResponses {
-                                       funding_locked, shutdown,
+                                       funding_locked, shutdown, announcement_sigs,
                                        commitment_update: None, raa: None, mon_update: None,
                                        order: self.resend_order.clone(),
                                        holding_cell_failed_htlcs: Vec::new(),
                                })
                        } else {
                                Ok(ReestablishResponses {
-                                       funding_locked, shutdown,
+                                       funding_locked, shutdown, announcement_sigs,
                                        raa: required_revoke,
                                        commitment_update: Some(self.get_last_commitment_update(logger)),
                                        order: self.resend_order.clone(),
@@ -4044,6 +4119,11 @@ impl<Signer: Sign> Channel<Signer> {
                self.short_channel_id
        }
 
+       /// Allowed in any state (including after shutdown)
+       pub fn get_latest_inbound_scid_alias(&self) -> Option<u64> {
+               self.latest_inbound_scid_alias
+       }
+
        /// Returns the funding_txo we either got from our peer, or were given by
        /// get_outbound_funding_created.
        pub fn get_funding_txo(&self) -> Option<OutPoint> {
@@ -4292,10 +4372,12 @@ 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,
+                                               short_channel_id_alias: None,
                                        });
                                }
                        } else {
@@ -4308,11 +4390,12 @@ impl<Signer: Sign> Channel<Signer> {
        /// When a transaction is confirmed, we check whether it is or spends the funding transaction
        /// In the first case, we store the confirmation height and calculating the short channel id.
        /// In the second, we simply return an Err indicating we need to be force-closed now.
-       pub fn transactions_confirmed<L: Deref>(&mut self, block_hash: &BlockHash, height: u32, txdata: &TransactionData, logger: &L)
-       -> Result<Option<msgs::FundingLocked>, ClosureReason> where L::Target: Logger {
+       pub fn transactions_confirmed<L: Deref>(&mut self, block_hash: &BlockHash, height: u32,
+               txdata: &TransactionData, genesis_block_hash: BlockHash, node_pk: PublicKey, logger: &L)
+       -> Result<(Option<msgs::FundingLocked>, Option<msgs::AnnouncementSignatures>), ClosureReason> where L::Target: Logger {
                let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
-               for &(index_in_block, tx) in txdata.iter() {
-                       if let Some(funding_txo) = self.get_funding_txo() {
+               if let Some(funding_txo) = self.get_funding_txo() {
+                       for &(index_in_block, tx) in txdata.iter() {
                                // If we haven't yet sent a funding_locked, but are in FundingSent (ignoring
                                // whether they've sent a funding_locked or not), check if we should send one.
                                if non_shutdown_state & !(ChannelState::TheirFundingLocked as u32) == ChannelState::FundingSent as u32 {
@@ -4356,7 +4439,8 @@ impl<Signer: Sign> Channel<Signer> {
                                        // may have already happened for this block).
                                        if let Some(funding_locked) = self.check_get_funding_locked(height) {
                                                log_info!(logger, "Sending a funding_locked to our peer for channel {}", log_bytes!(self.channel_id));
-                                               return Ok(Some(funding_locked));
+                                               let announcement_sigs = self.get_announcement_sigs(node_pk, genesis_block_hash, height, logger);
+                                               return Ok((Some(funding_locked), announcement_sigs));
                                        }
                                }
                                for inp in tx.input.iter() {
@@ -4367,7 +4451,7 @@ impl<Signer: Sign> Channel<Signer> {
                                }
                        }
                }
-               Ok(None)
+               Ok((None, None))
        }
 
        /// When a new block is connected, we check the height of the block against outbound holding
@@ -4381,8 +4465,13 @@ impl<Signer: Sign> Channel<Signer> {
        ///
        /// May return some HTLCs (and their payment_hash) which have timed out and should be failed
        /// back.
-       pub fn best_block_updated<L: Deref>(&mut self, height: u32, highest_header_time: u32, logger: &L)
-       -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>), ClosureReason> where L::Target: Logger {
+       pub fn best_block_updated<L: Deref>(&mut self, height: u32, highest_header_time: u32, genesis_block_hash: BlockHash, node_pk: PublicKey, logger: &L)
+       -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>, Option<msgs::AnnouncementSignatures>), ClosureReason> where L::Target: Logger {
+               self.do_best_block_updated(height, highest_header_time, Some((genesis_block_hash, node_pk)), logger)
+       }
+
+       fn do_best_block_updated<L: Deref>(&mut self, height: u32, highest_header_time: u32, genesis_node_pk: Option<(BlockHash, PublicKey)>, logger: &L)
+       -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>, Option<msgs::AnnouncementSignatures>), ClosureReason> where L::Target: Logger {
                let mut timed_out_htlcs = Vec::new();
                // This mirrors the check in ChannelManager::decode_update_add_htlc_onion, refusing to
                // forward an HTLC when our counterparty should almost certainly just fail it for expiring
@@ -4403,8 +4492,11 @@ impl<Signer: Sign> Channel<Signer> {
                self.update_time_counter = cmp::max(self.update_time_counter, highest_header_time);
 
                if let Some(funding_locked) = self.check_get_funding_locked(height) {
+                       let announcement_sigs = if let Some((genesis_block_hash, node_pk)) = genesis_node_pk {
+                               self.get_announcement_sigs(node_pk, genesis_block_hash, height, logger)
+                       } else { None };
                        log_info!(logger, "Sending a funding_locked to our peer for channel {}", log_bytes!(self.channel_id));
-                       return Ok((Some(funding_locked), timed_out_htlcs));
+                       return Ok((Some(funding_locked), timed_out_htlcs, announcement_sigs));
                }
 
                let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
@@ -4436,7 +4528,10 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ClosureReason::FundingTimedOut);
                }
 
-               Ok((None, timed_out_htlcs))
+               let announcement_sigs = if let Some((genesis_block_hash, node_pk)) = genesis_node_pk {
+                       self.get_announcement_sigs(node_pk, genesis_block_hash, height, logger)
+               } else { None };
+               Ok((None, timed_out_htlcs, announcement_sigs))
        }
 
        /// Indicates the funding transaction is no longer confirmed in the main chain. This may
@@ -4451,10 +4546,11 @@ impl<Signer: Sign> Channel<Signer> {
                        // larger. If we don't know that time has moved forward, we can just set it to the last
                        // time we saw and it will be ignored.
                        let best_time = self.update_time_counter;
-                       match self.best_block_updated(reorg_height, best_time, logger) {
-                               Ok((funding_locked, timed_out_htlcs)) => {
+                       match self.do_best_block_updated(reorg_height, best_time, None, logger) {
+                               Ok((funding_locked, timed_out_htlcs, announcement_sigs)) => {
                                        assert!(funding_locked.is_none(), "We can't generate a funding with 0 confirmations?");
                                        assert!(timed_out_htlcs.is_empty(), "We can't have accepted HTLCs with a timeout before our funding confirmation?");
+                                       assert!(announcement_sigs.is_none(), "We can't generate an announcement_sigs with 0 confirmations?");
                                        Ok(())
                                },
                                Err(e) => Err(e)
@@ -4638,12 +4734,43 @@ impl<Signer: Sign> Channel<Signer> {
                Ok(msg)
        }
 
-       pub fn get_announcement_sigs(&self, node_pk: PublicKey, genesis_block_hash: BlockHash) -> Result<msgs::AnnouncementSignatures, ChannelError> {
-               let announcement = self.get_channel_announcement(node_pk, genesis_block_hash)?;
-               let (our_node_sig, our_bitcoin_sig) = self.holder_signer.sign_channel_announcement(&announcement, &self.secp_ctx)
-                       .map_err(|_| ChannelError::Ignore("Signer rejected channel_announcement".to_owned()))?;
+       fn get_announcement_sigs<L: Deref>(&mut self, node_pk: PublicKey, genesis_block_hash: BlockHash, best_block_height: u32, logger: &L)
+       -> Option<msgs::AnnouncementSignatures> where L::Target: Logger {
+               if self.funding_tx_confirmation_height == 0 || self.funding_tx_confirmation_height + 5 > best_block_height {
+                       return None;
+               }
 
-               Ok(msgs::AnnouncementSignatures {
+               if !self.is_usable() {
+                       return None;
+               }
+
+               if self.channel_state & ChannelState::PeerDisconnected as u32 != 0 {
+                       log_trace!(logger, "Cannot create an announcement_signatures as our peer is disconnected");
+                       return None;
+               }
+
+               if self.announcement_sigs_state != AnnouncementSigsState::NotSent {
+                       return None;
+               }
+
+               log_trace!(logger, "Creating an announcement_signatures message for channel {}", log_bytes!(self.channel_id()));
+               let announcement = match self.get_channel_announcement(node_pk, genesis_block_hash) {
+                       Ok(a) => a,
+                       Err(_) => {
+                               log_trace!(logger, "Cannot create an announcement_signatures as channel is not public.");
+                               return None;
+                       }
+               };
+               let (our_node_sig, our_bitcoin_sig) = match self.holder_signer.sign_channel_announcement(&announcement, &self.secp_ctx) {
+                       Err(_) => {
+                               log_error!(logger, "Signer rejected channel_announcement signing. Channel will not be announced!");
+                               return None;
+                       },
+                       Ok(v) => v
+               };
+               self.announcement_sigs_state = AnnouncementSigsState::MessageSent;
+
+               Some(msgs::AnnouncementSignatures {
                        channel_id: self.channel_id(),
                        short_channel_id: self.get_short_channel_id().unwrap(),
                        node_signature: our_node_sig,
@@ -4674,7 +4801,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// Processes an incoming announcement_signatures message, providing a fully-signed
        /// channel_announcement message which we can broadcast and storing our counterparty's
        /// signatures for later reconstruction/rebroadcast of the channel_announcement.
-       pub fn announcement_signatures(&mut self, our_node_id: PublicKey, chain_hash: BlockHash, msg: &msgs::AnnouncementSignatures) -> Result<msgs::ChannelAnnouncement, ChannelError> {
+       pub fn announcement_signatures(&mut self, our_node_id: PublicKey, chain_hash: BlockHash, best_block_height: u32, msg: &msgs::AnnouncementSignatures) -> Result<msgs::ChannelAnnouncement, ChannelError> {
                let announcement = self.get_channel_announcement(our_node_id.clone(), chain_hash)?;
 
                let msghash = hash_to_message!(&Sha256d::hash(&announcement.encode()[..])[..]);
@@ -4691,13 +4818,20 @@ impl<Signer: Sign> Channel<Signer> {
                }
 
                self.announcement_sigs = Some((msg.node_signature, msg.bitcoin_signature));
+               if self.funding_tx_confirmation_height == 0 || self.funding_tx_confirmation_height + 5 > best_block_height {
+                       return Err(ChannelError::Ignore(
+                               "Got announcement_signatures prior to the required six confirmations - we may not have received a block yet that our peer has".to_owned()));
+               }
 
                self.sign_channel_announcement(our_node_id, announcement)
        }
 
        /// Gets a signed channel_announcement for this channel, if we previously received an
        /// announcement_signatures from our counterparty.
-       pub fn get_signed_channel_announcement(&self, our_node_id: PublicKey, chain_hash: BlockHash) -> Option<msgs::ChannelAnnouncement> {
+       pub fn get_signed_channel_announcement(&self, our_node_id: PublicKey, chain_hash: BlockHash, best_block_height: u32) -> Option<msgs::ChannelAnnouncement> {
+               if self.funding_tx_confirmation_height == 0 || self.funding_tx_confirmation_height + 5 > best_block_height {
+                       return None;
+               }
                let announcement = match self.get_channel_announcement(our_node_id.clone(), chain_hash) {
                        Ok(res) => res,
                        Err(_) => return None,
@@ -4977,6 +5111,10 @@ impl<Signer: Sign> Channel<Signer> {
                        Err(e) => return Err(e),
                };
 
+               if self.announcement_sigs_state == AnnouncementSigsState::MessageSent {
+                       self.announcement_sigs_state = AnnouncementSigsState::Committed;
+               }
+
                self.latest_monitor_update_id += 1;
                let monitor_update = ChannelMonitorUpdate {
                        update_id: self.latest_monitor_update_id,
@@ -5236,6 +5374,29 @@ impl Readable for ChannelUpdateStatus {
        }
 }
 
+impl Writeable for AnnouncementSigsState {
+       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+               // We only care about writing out the current state as if we had just disconnected, at
+               // which point we always set anything but AnnouncementSigsReceived to NotSent.
+               match self {
+                       AnnouncementSigsState::NotSent => 0u8.write(writer),
+                       AnnouncementSigsState::MessageSent => 0u8.write(writer),
+                       AnnouncementSigsState::Committed => 0u8.write(writer),
+                       AnnouncementSigsState::PeerReceived => 1u8.write(writer),
+               }
+       }
+}
+
+impl Readable for AnnouncementSigsState {
+       fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+               Ok(match <u8 as Readable>::read(reader)? {
+                       0 => AnnouncementSigsState::NotSent,
+                       1 => AnnouncementSigsState::PeerReceived,
+                       _ => return Err(DecodeError::InvalidValue),
+               })
+       }
+}
+
 impl<Signer: Sign> Writeable for Channel<Signer> {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                // Note that we write out as if remove_uncommitted_htlcs_and_mark_paused had just been
@@ -5493,6 +5654,8 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                        (9, self.target_closing_feerate_sats_per_kw, option),
                        (11, self.monitor_pending_finalized_fulfills, vec_type),
                        (13, self.channel_creation_height, required),
+                       (15, self.announcement_sigs_state, required),
+                       (17, self.latest_inbound_scid_alias, option),
                });
 
                Ok(())
@@ -5734,6 +5897,10 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
                // only, so we default to that if none was written.
                let mut channel_type = Some(ChannelTypeFeatures::only_static_remote_key());
                let mut channel_creation_height = Some(serialized_height);
+               // If we read an old Channel, for simplicity we just treat it as "we never sent an
+               // AnnouncementSignatures" which implies we'll re-send it on reconnect, but that's fine.
+               let mut announcement_sigs_state = Some(AnnouncementSigsState::NotSent);
+               let mut latest_inbound_scid_alias = None;
                read_tlv_fields!(reader, {
                        (0, announcement_sigs, option),
                        (1, minimum_depth, option),
@@ -5746,6 +5913,8 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
                        (9, target_closing_feerate_sats_per_kw, option),
                        (11, monitor_pending_finalized_fulfills, vec_type),
                        (13, channel_creation_height, option),
+                       (15, announcement_sigs_state, option),
+                       (17, latest_inbound_scid_alias, option),
                });
 
                let chan_features = channel_type.as_ref().unwrap();
@@ -5769,6 +5938,7 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
                        config: config.unwrap(),
                        channel_id,
                        channel_state,
+                       announcement_sigs_state: announcement_sigs_state.unwrap(),
                        secp_ctx,
                        channel_value_satoshis,
 
@@ -5853,6 +6023,8 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
 
                        workaround_lnd_bug_4006: None,
 
+                       latest_inbound_scid_alias,
+
                        #[cfg(any(test, feature = "fuzztarget"))]
                        historical_inbound_htlc_fulfills,