API Updates
* `get_route` now takes a `Score` as an argument. `Score` is queried during
the route-finding process, returning the absolute amounts which you are
willing to pay to avoid routing over a given channel. As a default, a
`Scorer` is provided which returns a constant amount, with a suggested
default of 500 msat. This translates to a willingness to pay up to 500 msat
in additional fees per hop in order to avoid additional hops (#1124).
* `Event::PaymentPathFailed` now contains a `short_channel_id` field which may
be filled in with a channel that can be "blamed" for the payment failure.
Payment retries should likely avoid the given channel for some time (#1077).
* `PublicKey`s in `NetworkGraph` have been replaced with a `NodeId` struct
which contains only a simple `[u8; 33]`, substantially improving
`NetworkGraph` deserialization performance (#1107).
* `ChainMonitor`'s `HashMap` of `ChannelMonitor`s is now private, exposed via
`Chainmonitor::get_monitor` and `ChainMonitor::list_monitors` instead
(#1112).
* When an outbound channel is closed prior to the broadcasting of its funding
transaction, but after you call
`ChannelManager::funding_transaction_generated`, a new event type,
`Event::DiscardFunding`, is generated, informing you the transaction was not
broadcasted and that you can spend the same inputs again elsewhere (#1098).
* `ChannelManager::create_channel` now returns the temporary channel ID which
may later appear in `Event::ChannelClosed` or `ChannelDetails` prior to the
channel being funded (#1121).
* `Event::PaymentSent` now contains the payment hash as well as the payment
preimage (#1062).
* `ReadOnlyNetworkGraph::get_addresses` now returns owned `NetAddress` rather
than references. As a side-effect this method is now exposed in foreign
language bindings (#1115).
* The `Persist` and `ChannelMonitorUpdateErr` types have moved to the
`lightning::chain::chainmonitor` and `lightning::chain` modules,
respectively (#1112).
* `ChannelManager::send_payment` now returns a `PaymentId` which identifies a
payment (whether MPP or not) and can be used to retry the full payment or
MPP parts through `retry_payment` (#1096). Note that doing so is currently
*not* crash safe, and you may find yourself sending twice. It is recommended
that you *not* use the `retry_payment` API until the next release.
Bug Fixes
* Due to an earlier fix for the Lightning dust inflation vulnerability tracked
in CVE-2021-41591/CVE-2021-41592/CVE-2021-41593 in 0.0.100, we required
counterparties to accept a dust limit slightly lower than the dust limit now
required by other implementations. This appeared as, at least, latest lnd
always refusing to accept channels opened by LDK clients (#1065).
* If there are multiple channels available to the same counterparty,
`get_route` would only consider the channel listed last as available for
sending (#1100).
* `Persist` implementations returning
`ChannelMonitorUpdateErr::TemporaryFailure` from `watch_channel` previously
resulted in the `ChannelMonitor` not being stored at all, resulting in a
panic after monitor updating is complete (#1112).
* If payments are pending awaiting forwarding at startup, an
`Event::PendingHTLCsForwardable` event will always be provided. This ensures
user code calls `ChannelManager::process_pending_htlc_fowards` even if it
shut down while awaiting the batching timer during the previous run (#1076).
* If a call to `ChannelManager::send_payment` failed due to lack of
availability of funds locally, LDK would store the payment as pending
forever, with no ability to retry or fail it, leaking memory (#1109).
Serialization Compatibility
* All above new Events/fields are ignored by prior clients. All above new
Events/fields, except for `Event::PaymentSent::payment_hash` are not present
when reading objects serialized by prior versions of the library.
In total, this release features 32 files changed, 2248 insertions, and 1483
deletions in 51 commits from 7 authors, in alphabetical order:
* 1nF0rmed
* Duncan Dean
* Elias Rohrer
* Galder ZamarrenĖo
* Jeffrey Czyz
* Matt Corallo
* Valentine Wallace
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