Support all shutdown scripts defined in BOLT 2
[rust-lightning] / lightning / src / ln / channel.rs
index e08b8af49a3a40f5992f8e09b77f99f8279135fd..9f768d1535a168660b368611163decf26aa6ebc2 100644 (file)
@@ -9,15 +9,15 @@
 
 use bitcoin::blockdata::script::{Script,Builder};
 use bitcoin::blockdata::transaction::{TxIn, TxOut, Transaction, SigHashType};
-use bitcoin::blockdata::opcodes;
 use bitcoin::util::bip143;
 use bitcoin::consensus::encode;
 
 use bitcoin::hashes::Hash;
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hashes::sha256d::Hash as Sha256d;
-use bitcoin::hash_types::{Txid, BlockHash, WPubkeyHash};
+use bitcoin::hash_types::{Txid, BlockHash};
 
+use bitcoin::secp256k1::constants::PUBLIC_KEY_SIZE;
 use bitcoin::secp256k1::key::{PublicKey,SecretKey};
 use bitcoin::secp256k1::{Secp256k1,Signature};
 use bitcoin::secp256k1;
@@ -26,6 +26,7 @@ use ln::{PaymentPreimage, PaymentHash};
 use ln::features::{ChannelFeatures, InitFeatures};
 use ln::msgs;
 use ln::msgs::{DecodeError, OptionalField, DataLossProtect};
+use ln::script::ShutdownScript;
 use ln::channelmanager::{PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA, MAX_LOCAL_BREAKDOWN_TIMEOUT};
 use ln::chan_utils::{CounterpartyCommitmentSecrets, TxCreationKeys, HTLCOutputInCommitment, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT, make_funding_redeemscript, ChannelPublicKeys, CommitmentTransaction, HolderCommitmentTransaction, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, MAX_HTLCS, get_commitment_transaction_number_obscure_factor};
 use ln::chan_utils;
@@ -41,13 +42,14 @@ use util::errors::APIError;
 use util::config::{UserConfig,ChannelConfig};
 use util::scid_utils::scid_from_parts;
 
+use io;
 use prelude::*;
 use core::{cmp,mem,fmt};
+use core::convert::TryFrom;
 use core::ops::Deref;
 #[cfg(any(test, feature = "fuzztarget", debug_assertions))]
 use sync::Mutex;
 use bitcoin::hashes::hex::ToHex;
-use bitcoin::blockdata::opcodes::all::OP_PUSHBYTES_0;
 
 #[cfg(test)]
 pub struct ChannelValueStat {
@@ -306,6 +308,7 @@ pub struct CounterpartyForwardingInfo {
 enum UpdateFulfillFetch {
        NewClaim {
                monitor_update: ChannelMonitorUpdate,
+               htlc_value_msat: u64,
                msg: Option<msgs::UpdateFulfillHTLC>,
        },
        DuplicateClaim {},
@@ -319,6 +322,8 @@ pub enum UpdateFulfillCommitFetch {
        NewClaim {
                /// The ChannelMonitorUpdate which places the new payment preimage in the channel monitor
                monitor_update: ChannelMonitorUpdate,
+               /// The value of the HTLC which was claimed, in msat.
+               htlc_value_msat: u64,
                /// The update_fulfill message and commitment_signed message (if the claim was not placed
                /// in the holding cell).
                msgs: Option<(msgs::UpdateFulfillHTLC, msgs::CommitmentSigned)>,
@@ -336,6 +341,9 @@ pub enum UpdateFulfillCommitFetch {
 // Holder designates channel data owned for the benefice of the user client.
 // Counterparty designates channel data owned by the another channel participant entity.
 pub(super) struct Channel<Signer: Sign> {
+       #[cfg(any(test, feature = "_test_utils"))]
+       pub(crate) config: ChannelConfig,
+       #[cfg(not(any(test, feature = "_test_utils")))]
        config: ChannelConfig,
 
        user_id: u64,
@@ -348,7 +356,7 @@ pub(super) struct Channel<Signer: Sign> {
        latest_monitor_update_id: u64,
 
        holder_signer: Signer,
-       shutdown_pubkey: PublicKey,
+       shutdown_scriptpubkey: Option<ShutdownScript>,
        destination_script: Script,
 
        // Our commitment numbers start at 2^48-1 and count down, whereas the ones used in transaction
@@ -606,7 +614,7 @@ impl<Signer: Sign> Channel<Signer> {
                        latest_monitor_update_id: 0,
 
                        holder_signer,
-                       shutdown_pubkey: keys_provider.get_shutdown_pubkey(),
+                       shutdown_scriptpubkey: Some(keys_provider.get_shutdown_scriptpubkey()),
                        destination_script: keys_provider.get_destination_script(),
 
                        cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
@@ -822,11 +830,11 @@ impl<Signer: Sign> Channel<Signer> {
                                        // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
                                        if script.len() == 0 {
                                                None
-                                       // Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. Fail the channel
-                                       } else if is_unsupported_shutdown_script(&their_features, script) {
-                                               return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format. script: ({})", script.to_bytes().to_hex())));
                                        } else {
-                                               Some(script.clone())
+                                               match ShutdownScript::try_from((script.clone(), &their_features)) {
+                                                       Ok(shutdown_script) => Some(shutdown_script.into_inner()),
+                                                       Err(_) => return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format. script: ({})", script.to_bytes().to_hex()))),
+                                               }
                                        }
                                },
                                // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
@@ -850,7 +858,7 @@ impl<Signer: Sign> Channel<Signer> {
                        latest_monitor_update_id: 0,
 
                        holder_signer,
-                       shutdown_pubkey: keys_provider.get_shutdown_pubkey(),
+                       shutdown_scriptpubkey: Some(keys_provider.get_shutdown_scriptpubkey()),
                        destination_script: keys_provider.get_destination_script(),
 
                        cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
@@ -1129,8 +1137,10 @@ impl<Signer: Sign> Channel<Signer> {
 
        #[inline]
        fn get_closing_scriptpubkey(&self) -> Script {
-               let channel_close_key_hash = WPubkeyHash::hash(&self.shutdown_pubkey.serialize());
-               Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&channel_close_key_hash[..]).into_script()
+               // The shutdown scriptpubkey is set on channel opening when option_upfront_shutdown_script
+               // is signaled. Otherwise, it is set when sending a shutdown message. Calling this method
+               // outside of those situations will fail.
+               self.shutdown_scriptpubkey.clone().unwrap().into_inner()
        }
 
        #[inline]
@@ -1275,6 +1285,7 @@ impl<Signer: Sign> Channel<Signer> {
                // these, but for now we just have to treat them as normal.
 
                let mut pending_idx = core::usize::MAX;
+               let mut htlc_value_msat = 0;
                for (idx, htlc) in self.pending_inbound_htlcs.iter().enumerate() {
                        if htlc.htlc_id == htlc_id_arg {
                                assert_eq!(htlc.payment_hash, payment_hash_calc);
@@ -1294,6 +1305,7 @@ impl<Signer: Sign> Channel<Signer> {
                                        }
                                }
                                pending_idx = idx;
+                               htlc_value_msat = htlc.amount_msat;
                                break;
                        }
                }
@@ -1335,7 +1347,7 @@ impl<Signer: Sign> Channel<Signer> {
                                                        // TODO: We may actually be able to switch to a fulfill here, though its
                                                        // rare enough it may not be worth the complexity burden.
                                                        debug_assert!(false, "Tried to fulfill an HTLC that was already failed");
-                                                       return UpdateFulfillFetch::NewClaim { monitor_update, msg: None };
+                                                       return UpdateFulfillFetch::NewClaim { monitor_update, htlc_value_msat, msg: None };
                                                }
                                        },
                                        _ => {}
@@ -1347,7 +1359,7 @@ impl<Signer: Sign> Channel<Signer> {
                        });
                        #[cfg(any(test, feature = "fuzztarget"))]
                        self.historical_inbound_htlc_fulfills.insert(htlc_id_arg);
-                       return UpdateFulfillFetch::NewClaim { monitor_update, msg: None };
+                       return UpdateFulfillFetch::NewClaim { monitor_update, htlc_value_msat, msg: None };
                }
                #[cfg(any(test, feature = "fuzztarget"))]
                self.historical_inbound_htlc_fulfills.insert(htlc_id_arg);
@@ -1357,7 +1369,7 @@ impl<Signer: Sign> Channel<Signer> {
                        if let InboundHTLCState::Committed = htlc.state {
                        } else {
                                debug_assert!(false, "Have an inbound HTLC we tried to claim before it was fully committed to");
-                               return UpdateFulfillFetch::NewClaim { monitor_update, msg: None };
+                               return UpdateFulfillFetch::NewClaim { monitor_update, htlc_value_msat, msg: None };
                        }
                        log_trace!(logger, "Upgrading HTLC {} to LocalRemoved with a Fulfill in channel {}!", log_bytes!(htlc.payment_hash.0), log_bytes!(self.channel_id));
                        htlc.state = InboundHTLCState::LocalRemoved(InboundHTLCRemovalReason::Fulfill(payment_preimage_arg.clone()));
@@ -1365,6 +1377,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                UpdateFulfillFetch::NewClaim {
                        monitor_update,
+                       htlc_value_msat,
                        msg: Some(msgs::UpdateFulfillHTLC {
                                channel_id: self.channel_id(),
                                htlc_id: htlc_id_arg,
@@ -1375,7 +1388,7 @@ impl<Signer: Sign> Channel<Signer> {
 
        pub fn get_update_fulfill_htlc_and_commit<L: Deref>(&mut self, htlc_id: u64, payment_preimage: PaymentPreimage, logger: &L) -> Result<UpdateFulfillCommitFetch, (ChannelError, ChannelMonitorUpdate)> where L::Target: Logger {
                match self.get_update_fulfill_htlc(htlc_id, payment_preimage, logger) {
-                       UpdateFulfillFetch::NewClaim { mut monitor_update, msg: Some(update_fulfill_htlc) } => {
+                       UpdateFulfillFetch::NewClaim { mut monitor_update, htlc_value_msat, msg: Some(update_fulfill_htlc) } => {
                                let (commitment, mut additional_update) = match self.send_commitment_no_status_check(logger) {
                                        Err(e) => return Err((e, monitor_update)),
                                        Ok(res) => res
@@ -1384,9 +1397,10 @@ impl<Signer: Sign> Channel<Signer> {
                                // strictly increasing by one, so decrement it here.
                                self.latest_monitor_update_id = monitor_update.update_id;
                                monitor_update.updates.append(&mut additional_update.updates);
-                               Ok(UpdateFulfillCommitFetch::NewClaim { monitor_update, msgs: Some((update_fulfill_htlc, commitment)) })
+                               Ok(UpdateFulfillCommitFetch::NewClaim { monitor_update, htlc_value_msat, msgs: Some((update_fulfill_htlc, commitment)) })
                        },
-                       UpdateFulfillFetch::NewClaim { monitor_update, msg: None } => Ok(UpdateFulfillCommitFetch::NewClaim { monitor_update, msgs: None }),
+                       UpdateFulfillFetch::NewClaim { monitor_update, htlc_value_msat, msg: None } =>
+                               Ok(UpdateFulfillCommitFetch::NewClaim { monitor_update, htlc_value_msat, msgs: None }),
                        UpdateFulfillFetch::DuplicateClaim {} => Ok(UpdateFulfillCommitFetch::DuplicateClaim {}),
                }
        }
@@ -1549,11 +1563,11 @@ impl<Signer: Sign> Channel<Signer> {
                                        // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
                                        if script.len() == 0 {
                                                None
-                                       // Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. Fail the channel
-                                       } else if is_unsupported_shutdown_script(&their_features, script) {
-                                               return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format. script: ({})", script.to_bytes().to_hex())));
                                        } else {
-                                               Some(script.clone())
+                                               match ShutdownScript::try_from((script.clone(), &their_features)) {
+                                                       Ok(shutdown_script) => Some(shutdown_script.into_inner()),
+                                                       Err(_) => return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format. script: ({})", script.to_bytes().to_hex()))),
+                                               }
                                        }
                                },
                                // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
@@ -1675,8 +1689,9 @@ impl<Signer: Sign> Channel<Signer> {
                let funding_redeemscript = self.get_funding_redeemscript();
                let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
                let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
+               let shutdown_script = self.shutdown_scriptpubkey.clone().map(|script| script.into_inner());
                let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), self.holder_signer.clone(),
-                                                         &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
+                                                         shutdown_script, self.get_holder_selected_contest_delay(),
                                                          &self.destination_script, (funding_txo, funding_txo_script.clone()),
                                                          &self.channel_transaction_parameters,
                                                          funding_redeemscript.clone(), self.channel_value_satoshis,
@@ -1748,8 +1763,9 @@ impl<Signer: Sign> Channel<Signer> {
                let funding_txo = self.get_funding_txo().unwrap();
                let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
                let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
+               let shutdown_script = self.shutdown_scriptpubkey.clone().map(|script| script.into_inner());
                let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), self.holder_signer.clone(),
-                                                         &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
+                                                         shutdown_script, self.get_holder_selected_contest_delay(),
                                                          &self.destination_script, (funding_txo, funding_txo_script),
                                                          &self.channel_transaction_parameters,
                                                          funding_redeemscript.clone(), self.channel_value_satoshis,
@@ -2163,7 +2179,7 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// Marks an outbound HTLC which we have received update_fail/fulfill/malformed
        #[inline]
-       fn mark_outbound_htlc_removed(&mut self, htlc_id: u64, check_preimage: Option<PaymentHash>, fail_reason: Option<HTLCFailReason>) -> Result<&HTLCSource, ChannelError> {
+       fn mark_outbound_htlc_removed(&mut self, htlc_id: u64, check_preimage: Option<PaymentHash>, fail_reason: Option<HTLCFailReason>) -> Result<&OutboundHTLCOutput, ChannelError> {
                for htlc in self.pending_outbound_htlcs.iter_mut() {
                        if htlc.htlc_id == htlc_id {
                                match check_preimage {
@@ -2182,13 +2198,13 @@ impl<Signer: Sign> Channel<Signer> {
                                        OutboundHTLCState::AwaitingRemoteRevokeToRemove(_) | OutboundHTLCState::AwaitingRemovedRemoteRevoke(_) | OutboundHTLCState::RemoteRemoved(_) =>
                                                return Err(ChannelError::Close(format!("Remote tried to fulfill/fail HTLC ({}) that they'd already fulfilled/failed", htlc_id))),
                                }
-                               return Ok(&htlc.source);
+                               return Ok(htlc);
                        }
                }
                Err(ChannelError::Close("Remote tried to fulfill/fail an HTLC we couldn't find".to_owned()))
        }
 
-       pub fn update_fulfill_htlc(&mut self, msg: &msgs::UpdateFulfillHTLC) -> Result<HTLCSource, ChannelError> {
+       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()));
                }
@@ -2197,7 +2213,7 @@ impl<Signer: Sign> Channel<Signer> {
                }
 
                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(|source| source.clone())
+               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> {
@@ -2496,7 +2512,7 @@ impl<Signer: Sign> Channel<Signer> {
                                                // in it hitting the holding cell again and we cannot change the state of a
                                                // holding cell HTLC from fulfill to anything else.
                                                let (update_fulfill_msg_option, mut additional_monitor_update) =
-                                                       if let UpdateFulfillFetch::NewClaim { msg, monitor_update } = self.get_update_fulfill_htlc(htlc_id, *payment_preimage, logger) {
+                                                       if let UpdateFulfillFetch::NewClaim { msg, monitor_update, .. } = self.get_update_fulfill_htlc(htlc_id, *payment_preimage, logger) {
                                                                (msg, monitor_update)
                                                        } else { unreachable!() };
                                                update_fulfill_htlcs.push(update_fulfill_msg_option.unwrap());
@@ -3228,16 +3244,17 @@ impl<Signer: Sign> Channel<Signer> {
                }
                assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
 
-               if is_unsupported_shutdown_script(&their_features, &msg.scriptpubkey) {
-                       return Err(ChannelError::Close(format!("Got a nonstandard scriptpubkey ({}) from remote peer", msg.scriptpubkey.to_bytes().to_hex())));
-               }
+               let shutdown_scriptpubkey = match ShutdownScript::try_from((msg.scriptpubkey.clone(), their_features)) {
+                       Ok(script) => script.into_inner(),
+                       Err(_) => return Err(ChannelError::Close(format!("Got a nonstandard scriptpubkey ({}) from remote peer", msg.scriptpubkey.to_bytes().to_hex()))),
+               };
 
                if self.counterparty_shutdown_scriptpubkey.is_some() {
-                       if Some(&msg.scriptpubkey) != self.counterparty_shutdown_scriptpubkey.as_ref() {
-                               return Err(ChannelError::Close(format!("Got shutdown request with a scriptpubkey ({}) which did not match their previous scriptpubkey.", msg.scriptpubkey.to_bytes().to_hex())));
+                       if Some(&shutdown_scriptpubkey) != self.counterparty_shutdown_scriptpubkey.as_ref() {
+                               return Err(ChannelError::Close(format!("Got shutdown request with a scriptpubkey ({}) which did not match their previous scriptpubkey.", shutdown_scriptpubkey.to_bytes().to_hex())));
                        }
                } else {
-                       self.counterparty_shutdown_scriptpubkey = Some(msg.scriptpubkey.clone());
+                       self.counterparty_shutdown_scriptpubkey = Some(shutdown_scriptpubkey);
                }
 
                // From here on out, we may not fail!
@@ -4484,24 +4501,6 @@ impl<Signer: Sign> Channel<Signer> {
        }
 }
 
-fn is_unsupported_shutdown_script(their_features: &InitFeatures, script: &Script) -> bool {
-       // We restrain shutdown scripts to standards forms to avoid transactions not propagating on the p2p tx-relay network
-
-       // BOLT 2 says we must only send a scriptpubkey of certain standard forms,
-       // which for a a BIP-141-compliant witness program is at max 42 bytes in length.
-       // So don't let the remote peer feed us some super fee-heavy script.
-       let is_script_too_long = script.len() > 42;
-       if is_script_too_long {
-               return true;
-       }
-
-       if their_features.supports_shutdown_anysegwit() && script.is_witness_program() && script.as_bytes()[0] != OP_PUSHBYTES_0.into_u8() {
-               return false;
-       }
-
-       return !script.is_p2pkh() && !script.is_p2sh() && !script.is_v0_p2wpkh() && !script.is_v0_p2wsh()
-}
-
 const SERIALIZATION_VERSION: u8 = 2;
 const MIN_SERIALIZATION_VERSION: u8 = 1;
 
@@ -4512,7 +4511,7 @@ impl_writeable_tlv_based_enum!(InboundHTLCRemovalReason,;
 );
 
 impl Writeable for ChannelUpdateStatus {
-       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
+       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                // We only care about writing out the current state as it was announced, ie only either
                // Enabled or Disabled. In the case of DisabledStaged, we most recently announced the
                // channel as enabled, so we write 0. For EnabledStaged, we similarly write a 1.
@@ -4527,7 +4526,7 @@ impl Writeable for ChannelUpdateStatus {
 }
 
 impl Readable for ChannelUpdateStatus {
-       fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+       fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
                Ok(match <u8 as Readable>::read(reader)? {
                        0 => ChannelUpdateStatus::Enabled,
                        1 => ChannelUpdateStatus::Disabled,
@@ -4537,7 +4536,7 @@ impl Readable for ChannelUpdateStatus {
 }
 
 impl<Signer: Sign> Writeable for Channel<Signer> {
-       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
+       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
                // called.
 
@@ -4565,7 +4564,12 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                (key_data.0.len() as u32).write(writer)?;
                writer.write_all(&key_data.0[..])?;
 
-               self.shutdown_pubkey.write(writer)?;
+               // Write out the old serialization for shutdown_pubkey for backwards compatibility, if
+               // deserialized from that format.
+               match self.shutdown_scriptpubkey.as_ref().and_then(|script| script.as_legacy_pubkey()) {
+                       Some(shutdown_pubkey) => shutdown_pubkey.write(writer)?,
+                       None => [0u8; PUBLIC_KEY_SIZE].write(writer)?,
+               }
                self.destination_script.write(writer)?;
 
                self.cur_holder_commitment_transaction_number.write(writer)?;
@@ -4761,6 +4765,7 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                        (1, self.minimum_depth, option),
                        (3, self.counterparty_selected_channel_reserve_satoshis, option),
                        (5, self.config, required),
+                       (7, self.shutdown_scriptpubkey, option),
                });
 
                Ok(())
@@ -4770,7 +4775,7 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
 const MAX_ALLOC_SIZE: usize = 64*1024;
 impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                where K::Target: KeysInterface<Signer = Signer> {
-       fn read<R : ::std::io::Read>(reader: &mut R, keys_source: &'a K) -> Result<Self, DecodeError> {
+       fn read<R : io::Read>(reader: &mut R, keys_source: &'a K) -> Result<Self, DecodeError> {
                let ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
 
                let user_id = Readable::read(reader)?;
@@ -4804,7 +4809,11 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                }
                let holder_signer = keys_source.read_chan_signer(&keys_data)?;
 
-               let shutdown_pubkey = Readable::read(reader)?;
+               // Read the old serialization for shutdown_pubkey, preferring the TLV field later if set.
+               let mut shutdown_scriptpubkey = match <PublicKey as Readable>::read(reader) {
+                       Ok(pubkey) => Some(ShutdownScript::new_p2wpkh_from_pubkey(pubkey)),
+                       Err(_) => None,
+               };
                let destination_script = Readable::read(reader)?;
 
                let cur_holder_commitment_transaction_number = Readable::read(reader)?;
@@ -4975,6 +4984,7 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                        (1, minimum_depth, option),
                        (3, counterparty_selected_channel_reserve_satoshis, option),
                        (5, config, option), // Note that if none is provided we will *not* overwrite the existing one.
+                       (7, shutdown_scriptpubkey, option),
                });
 
                let mut secp_ctx = Secp256k1::new();
@@ -4992,7 +5002,7 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                        latest_monitor_update_id,
 
                        holder_signer,
-                       shutdown_pubkey,
+                       shutdown_scriptpubkey,
                        destination_script,
 
                        cur_holder_commitment_transaction_number,
@@ -5085,6 +5095,7 @@ mod tests {
        use ln::channel::MAX_FUNDING_SATOSHIS;
        use ln::features::InitFeatures;
        use ln::msgs::{ChannelUpdate, DataLossProtect, DecodeError, OptionalField, UnsignedChannelUpdate};
+       use ln::script::ShutdownScript;
        use ln::chan_utils;
        use ln::chan_utils::{ChannelPublicKeys, HolderCommitmentTransaction, CounterpartyChannelTransactionParameters, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT};
        use chain::BestBlock;
@@ -5134,10 +5145,10 @@ mod tests {
                        Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&channel_monitor_claim_key_hash[..]).into_script()
                }
 
-               fn get_shutdown_pubkey(&self) -> PublicKey {
+               fn get_shutdown_scriptpubkey(&self) -> ShutdownScript {
                        let secp_ctx = Secp256k1::signing_only();
                        let channel_close_key = SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap();
-                       PublicKey::from_secret_key(&secp_ctx, &channel_close_key)
+                       ShutdownScript::new_p2wpkh_from_pubkey(PublicKey::from_secret_key(&secp_ctx, &channel_close_key))
                }
 
                fn get_channel_signer(&self, _inbound: bool, _channel_value_satoshis: u64) -> InMemorySigner {