LDK v0.0.116: Lightning Anchor Channels Support

• "LDK is based on Rust-Lightning, a full-featured but also incredibly flexible lightning implementation, allowing you to decide how to use it."
• "Learn how to start adding Lightning to your apps at lightningdevkit.org."

What's new

API Updates

• Support for zero-HTLC-fee anchor output channels has been added and is now considered beta (#2367). Users who set ChannelHandshakeConfig::negotiate_anchors_zero_fee_htlc_tx should be
  prepared to handle the new Event::BumpTransaction, e.g. via the
  BumpTransactionEventHandler (#2089). Note that in order to do so you must ensure you always have a reserve of available unspent on-chain funds to use for CPFP. LDK currently makes no attempt to ensure this for you.
• Users who set ChannelHandshakeConfig::negotiate_anchors_zero_fee_htlc_tx and wish to accept inbound anchor-based channels must do so manually by setting UserConfig::manually_accept_inbound_channels (#2368).
• Support forwarding and accepting HTLCs with a reduced amount has been added, to support LSPs skimming a fee on the penultimate hop (#2319).
• BOLT11 and BOLT12 Invoice and related types have been renamed to include a BOLTNN prefix, ensuring uniqueness in lightning{,-invoice} crates (#2416).
• Scorers now have an associated type which represents a parameter passed when calculating penalties. This allows for the same Scorer to be used with different penalty calculation parameters (#2237).
• DefaultRouter is no longer restrained to a Mutex-wrapped Score,
  allowing it to be used in no-std builds (#2383).
• CustomMessageHandler::provided_{node,init}_features and various custom feature bit methods on *Features were added (#2204).
• Keysend/push payments using MPP are now supported when receiving if UserConfig::accept_mpp_keysend is set and when sending if specified in the PaymentParameters. Note that not all recipients support this (#2156).
• A new ConfirmationTarget::MempoolMinimum has been added (#2415).
• SpendableOutputDescriptor::to_psbt_input was added (#2286).
• ChannelManager::update_partial_channel_config was added (#2330).
• ChannelDetails::channel_shutdown_state was added (#2347).
• The shutdown script can now be provided at shutdown time via
  ChannelManager::close_channel_with_feerate_and_script (#2219).
• BroadcasterInterface now takes multiple transactions at once. While not available today, in the future single calls should be passed to a full node via a single batch/package transaction acceptance API (#2272).
• Balance::claimable_amount_satoshis was added (#2333).
• payment_{hash,preimage} have been added to some Balance variants (#2217).
• The lightning::chain::keysinterface is now lightning::sign (#2246).
• Routing to a blinded path has been implemented, though sending to such a route is not yet supported in ChannelManager (#2120).
• OffersMessageHandler was added for offers-related onion messages (#2294).
• The CustomMessageHandler parameter to PeerManager has moved to
  MessageHandler from PeerManager::new explicitly (#2249).
• Various P2P messages for dual funding channel establishment have been added, though handling for them is not yet in ChannelManager (#1794)
• Script-fetching methods in sign interfaces can now return errors, see docs for the implications of failing (#2213).
• The data_loss_protect option is now required when reading
  channel_reestablish messages, as many others have done (#2253).
• InFlightHtlcs::add_inflight_htlc has been added (#2042).
• The init message networks field is now written and checked (#2329).
• PeerManager generics have been simplified with the introduction of the APeerManager trait (#2249).
• ParitalOrd and Ord are now implemented for Invoice (#2279).
• ParitalEq and Debug are now implemented for InMemorySigner (#2328).
• ParitalEq and Eq are now implemented for PaymentError (#2316).
• NetworkGraph::update_channel_from_announcement_no_lookup was added (#2222).
• lightning::routing::gossip::verify_{channel,node}_announcement was added (#2307).

Backwards Compatibility

• PaymentParameters written with blinded path info using LDK 0.0.115 will not be readable in LDK 0.0.116, and vice versa.
• Forwarding less than Event::HTLCIntercepted::expected_outbound_amount_msat in ChannelManager::forward_intercepted_htlc may prevent the ChannelManager from being read by LDK prior to 0.0.116 (#2319)
• Setting ChannelConfig::accept_underpaying_htlcs may prevent the
  ChannelManager from being read by LDK prior to 0.0.116 and un-setting the parameter between restarts may lead to payment failures (#2319).
• ChannelManager::create_inbound_payment{,_for_hash}_legacy has been removed, removing the ability to create inbound payments which are claimable after downgrade to LDK 0.0.103 and prior. In the future handling such payments will also be removed (#2351).
• Some fields required by LDK 0.0.103 and earlier are no longer written, thus deserializing objects written by 0.0.116 with 0.0.103 may now fail (#2351).

Bug Fixes

• ChannelDetails::next_outbound_htlc_limit_msat was made substantially more accurate and a corresponding next_outbound_htlc_minimum_msat was added.
  This resolves issues where unpayable routes were generated due to
  overestimation of the amount which is payable over one of our channels as the first hop (#2312).
• A rare case where delays in processing Events generated by
  ChannelMonitors could lead to loss of those events in case of an untimely crash. This could lead to the loss of an Event::SpendableOutputs (#2369).
• Fixed a regression in 0.0.115 which caused PendingHTLCsForwardable events to be missed when processing phantom node receives. This caused such payments to be delayed until a further, unrelated HTLC came in (#2395).
• Peers which are unresponsive to channel messages for several timer ticks are now disconnected to allow for on-reconnection state machine reset. This works around some issues in LND prior to 16.3 which can cause channels to hang and eventually force-close (#2293).
• ChannelManager::new now requires the current time (either from a recent block header or the system clock), ensuring invoices created immediately after startup aren't already expired (#2372).
• Resolved an issue where reading a ProbabilisticScorer on some platforms (e.g. iOS) can lead to a panic (#2322).
• ChannelConfig::max_dust_htlc_exposure is now allowed to scale based on current fees, and the default has been updated to do so. This substantially reduces the chance of force-closure due to dust exposure. Note that existing channels will retain their current value and you may wish to update the value on your existing channels on upgrade (#2354).
• PeerManager::process_events no longer blocks in any case. This fixes a bug where reentrancy from PeerManager into user code which eventually calls process_events could lead to a deadlock (#2280).
• The persist timing of network graph and scoring in lightning-background-processor has been tweaked to provide more reliable
  persistence after updates to either (#2226).
• The number of route hints added to BOLT 11 invoices by the
  lightning-invoice::utils builders has been reduced to three to ensure invoices can be represented in scan-able QR codes (#2044).
• Fixed sending large onion messages, which would previously have resulted in an HMAC error on the second hop (#2277).
• Fixed a memory leak that may occur when a ChannelManager or
  ChannelMonitor is droped (#2233).
• A potential deadlock in calling NetworkGraph::eq was resolved (#2284).
• Fixed an overflow which prevented disconnecting peers in some minor cases with more than 31 peers (#2245).
• Gossip messages with an unknown chain hash are now ignored (#2230).
• Rapid Gossip Sync processing now fails on an unknown chain hash (#2324).
• RouteHintHop::htlc_maximum_msat is now enforced. Note that BOLT11 route hints do not have such a field so this code is generally unused (#2305).

Security

0.0.116 fixes a denial-of-service vulnerability which is reachable from
untrusted input from channel counterparties if a 0-conf channel exists with that counterparty.

• A premature announcement_signatures message from a peer prior to a 0-conf channel's funding transaction receiving any confirmations would panic in any version since 0-conf channels were introduced (#2439).

In total, this release features 142 files changed, 21033 insertions, 11066
deletions in 327 commits from 21 authors, in alphabetical order:

• Alec Chen
• Andrei
• Antoine Riard
• Arik Sosman
• Chad Upjohn
• Daniel Granhão
• Duncan Dean
• Elias Rohrer
• Fred Walker
• Gleb Naumenko
• Jeffrey Czyz
• Martin Habovstiak
• Matt Corallo
• Tony Giorgio
• Valentine Wallace
• Vladimir Fomene
• Willem Van Lint
• Wilmer Paulino
• benthecarman
• ff
• henghonglee

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