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Include excess counterparty commitment transaction fees in dust exposure #3045

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merged 6 commits into from
May 7, 2024

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TheBlueMatt
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Transaction fees on counterparty commitment transactions are
ultimately not our money and thus are really "dust" from our PoV -
they're funds that may be ours during off-chain updates but are not
ours once we go on-chain.

Thus, here, we count any such fees in excess of our own fee
estimates towards dust exposure. We don't bother to make an
inbound/outbound channel distinction here as in most cases users
will use MaxDustExposure::FeeRateMultiplier which will scale
with the fee we set on outbound channels anyway.

Note that this also enables the dust exposure checks on anchor
channels during feerate updates. We'd previously elided these as
increases in the channel feerates do not change the HTLC dust
exposure, but now do for the fee dust exposure.

Also updates our default limit, fixing #2922

In most cases we already call both in a pair, and in fact always
consolidate some of the returned values across both accessors, so
there's not much reason to have them be separate methods.

Here we merge them.
The previous commit left indentation in `get_pending_htlc_stats`
deliberately wrong, to ease reviewability. This commit fixes the
indentation.
As LDK changes, `UserConfig::default()` may imply marginally
different behavior, whereas `test_default_channel_config` is
intended to tweak defaults to provide a stable behavior for test
contexts.

This commit changes a few uses of `UserConfig::default()` to
`test_default_channel_config` in cases that will fail over the
coming commits due to dust changes.
Transaction fees on counterparty commitment transactions are
ultimately not our money and thus are really "dust" from our PoV -
they're funds that may be ours during off-chain updates but are not
ours once we go on-chain.

Thus, here, we count any such fees in excess of our own fee
estimates towards dust exposure. We don't bother to make an
inbound/outbound channel distinction here as in most cases users
will use `MaxDustExposure::FeeRateMultiplier` which will scale
with the fee we set on outbound channels anyway.

Note that this also enables the dust exposure checks on anchor
channels during feerate updates. We'd previously elided these as
increases in the channel feerates do not change the HTLC dust
exposure, but now do for the fee dust exposure.
Now that we're including excess counterparty commitment transaction
fees in our dust calculation, we need to update the docs
accordingly. We do so here, describing some of the considerations
and risks that come with the new changes.

We also take this opportunity to double the default value, as users
have regularly complained that non-anchor channels fail to send
HTLCs with the default settings with some feerates.

Fixes lightningdevkit#2922
@TheBlueMatt TheBlueMatt added this to the 0.0.123 milestone May 7, 2024
@TheBlueMatt TheBlueMatt linked an issue May 7, 2024 that may be closed by this pull request
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Codecov Report

Attention: Patch coverage is 94.03974% with 18 lines in your changes are missing coverage. Please review.

Project coverage is 90.65%. Comparing base (8701b1b) to head (5091c1f).
Report is 37 commits behind head on main.

Files Patch % Lines
lightning/src/ln/channel.rs 93.49% 9 Missing and 2 partials ⚠️
lightning/src/ln/functional_tests.rs 94.53% 6 Missing and 1 partial ⚠️

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Additional details and impacted files
@@            Coverage Diff             @@
##             main    #3045      +/-   ##
==========================================
+ Coverage   89.16%   90.65%   +1.48%     
==========================================
  Files         118      118              
  Lines       97726   102485    +4759     
  Branches    97726   102485    +4759     
==========================================
+ Hits        87142    92904    +5762     
+ Misses       8345     7135    -1210     
- Partials     2239     2446     +207     

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@jkczyz
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jkczyz commented May 7, 2024

Fuzz tests failing 😢

@TheBlueMatt
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Grr, its just the stupid no_existing_breakage test. I'll work on it but IMO we can merge it with that broken, cut an RC, and then fix for release.

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LGTM. Thanks for the docs :)

@TheBlueMatt TheBlueMatt merged commit d1ac071 into lightningdevkit:main May 7, 2024
14 of 16 checks passed
TheBlueMatt added a commit to TheBlueMatt/rust-lightning that referenced this pull request May 7, 2024
…-are-dust

Include excess counterparty commitment transaction fees in dust exposure
k0k0ne pushed a commit to bitlightlabs/rust-lightning that referenced this pull request Sep 30, 2024
v0.0.123 - May 08, 2024 - "BOLT12 Dust Sweeping"

API Updates
===========

 * To reduce risk of force-closures and improve HTLC reliability the default
   dust exposure limit has been increased to
   `MaxDustHTLCExposure::FeeRateMultiplier(10_000)`. Users with existing
   channels might want to consider using
   `ChannelManager::update_channel_config` to apply the new default (lightningdevkit#3045).
 * `ChainMonitor::archive_fully_resolved_channel_monitors` is now provided to
   remove from memory `ChannelMonitor`s that have been fully resolved on-chain
   and are now not needed. It uses the new `Persist::archive_persisted_channel`
   to inform the storage layer that such a monitor should be archived (lightningdevkit#2964).
 * An `OutputSweeper` is now provided which will automatically sweep
   `SpendableOutputDescriptor`s, retrying until the sweep confirms (lightningdevkit#2825).
 * After initiating an outbound channel, a peer disconnection no longer results
   in immediate channel closure. Rather, if the peer is reconnected before the
   channel times out LDK will automatically retry opening it (lightningdevkit#2725).
 * `PaymentPurpose` now has separate variants for BOLT12 payments, which
   include fields from the `invoice_request` as well as the `OfferId` (lightningdevkit#2970).
 * `ChannelDetails` now includes a list of in-flight HTLCs (lightningdevkit#2442).
 * `Event::PaymentForwarded` now includes `skimmed_fee_msat` (lightningdevkit#2858).
 * The `hashbrown` dependency has been upgraded and the use of `ahash` as the
   no-std hash table hash function has been removed. As a consequence, LDK's
   `Hash{Map,Set}`s no longer feature several constructors when LDK is built
   with no-std; see the `util::hash_tables` module instead. On platforms that
   `getrandom` supports, setting the `possiblyrandom/getrandom` feature flag
   will ensure hash tables are resistant to HashDoS attacks, though the
   `possiblyrandom` crate should detect most common platforms (lightningdevkit#2810, lightningdevkit#2891).
 * `ChannelMonitor`-originated requests to the `ChannelSigner` can now fail and
   be retried using `ChannelMonitor::signer_unblocked` (lightningdevkit#2816).
 * `SpendableOutputDescriptor::to_psbt_input` now includes the `witness_script`
   where available as well as new proprietary data which can be used to
   re-derive some spending keys from the base key (lightningdevkit#2761, lightningdevkit#3004).
 * `OutPoint::to_channel_id` has been removed in favor of
   `ChannelId::v1_from_funding_outpoint` in preparation for v2 channels with a
   different `ChannelId` derivation scheme (lightningdevkit#2797).
 * `PeerManager::get_peer_node_ids` has been replaced with `list_peers` and
   `peer_by_node_id`, which provide more details (lightningdevkit#2905).
 * `Bolt11Invoice::get_payee_pub_key` is now provided (lightningdevkit#2909).
 * `Default[Message]Router` now take an `entropy_source` argument (lightningdevkit#2847).
 * `ClosureReason::HTLCsTimedOut` has been separated out from
   `ClosureReason::HolderForceClosed` as it is the most common case (lightningdevkit#2887).
 * `ClosureReason::CooperativeClosure` is now split into
   `{Counterparty,Locally}Initiated` variants (lightningdevkit#2863).
 * `Event::ChannelPending::channel_type` is now provided (lightningdevkit#2872).
 * `PaymentForwarded::{prev,next}_user_channel_id` are now provided (lightningdevkit#2924).
 * Channel init messages have been refactored towards V2 channels (lightningdevkit#2871).
 * `BumpTransactionEvent` now contains the channel and counterparty (lightningdevkit#2873).
 * `util::scid_utils` is now public, with some trivial utilities to examine
   short channel ids (lightningdevkit#2694).
 * `DirectedChannelInfo::{source,target}` are now public (lightningdevkit#2870).
 * Bounds in `lightning-background-processor` were simplified by using
   `AChannelManager` (lightningdevkit#2963).
 * The `Persist` impl for `KVStore` no longer requires `Sized`, allowing for
   the use of `dyn KVStore` as `Persist` (lightningdevkit#2883, lightningdevkit#2976).
 * `From<PaymentPreimage>` is now implemented for `PaymentHash` (lightningdevkit#2918).
 * `NodeId::from_slice` is now provided (lightningdevkit#2942).
 * `ChannelManager` deserialization may now fail with `DangerousValue` when
    LDK's persistence API was violated (lightningdevkit#2974).

Bug Fixes
=========

 * Excess fees on counterparty commitment transactions are now included in the
   dust exposure calculation. This lines behavior up with some cases where
   transaction fees can be burnt, making them effectively dust exposure (lightningdevkit#3045).
 * `Future`s used as an `std::...::Future` could grow in size unbounded if it
   was never woken. For those not using async persistence and using the async
   `lightning-background-processor`, this could cause a memory leak in the
   `ChainMonitor` (lightningdevkit#2894).
 * Inbound channel requests that fail in
   `ChannelManager::accept_inbound_channel` would previously have stalled from
   the peer's perspective as no `error` message was sent (lightningdevkit#2953).
 * Blinded path construction has been tuned to select paths more likely to
   succeed, improving BOLT12 payment reliability (lightningdevkit#2911, lightningdevkit#2912).
 * After a reorg, `lightning-transaction-sync` could have failed to follow a
   transaction that LDK needed information about (lightningdevkit#2946).
 * `RecipientOnionFields`' `custom_tlvs` are now propagated to recipients when
   paying with blinded paths (lightningdevkit#2975).
 * `Event::ChannelClosed` is now properly generated and peers are properly
   notified for all channels that as a part of a batch channel open fail to be
   funded (lightningdevkit#3029).
 * In cases where user event processing is substantially delayed such that we
   complete multiple round-trips with our peers before a `PaymentSent` event is
   handled and then restart without persisting the `ChannelManager` after having
   persisted a `ChannelMonitor[Update]`, on startup we may have `Err`d trying to
   deserialize the `ChannelManager` (lightningdevkit#3021).
 * If a peer has relatively high latency, `PeerManager` may have failed to
   establish a connection (lightningdevkit#2993).
 * `ChannelUpdate` messages broadcasted for our own channel closures are now
   slightly more robust (lightningdevkit#2731).
 * Deserializing malformed BOLT11 invoices may have resulted in an integer
   overflow panic in debug builds (lightningdevkit#3032).
 * In exceedingly rare cases (no cases of this are known), LDK may have created
   an invalid serialization for a `ChannelManager` (lightningdevkit#2998).
 * Message processing latency handling BOLT12 payments has been reduced (lightningdevkit#2881).
 * Latency in processing `Event::SpendableOutputs` may be reduced (lightningdevkit#3033).

Node Compatibility
==================

 * LDK's blinded paths were inconsistent with other implementations in several
   ways, which have been addressed (lightningdevkit#2856, lightningdevkit#2936, lightningdevkit#2945).
 * LDK's messaging blinded paths now support the latest features which some
   nodes may begin relying on soon (lightningdevkit#2961).
 * LDK's BOLT12 structs have been updated to support some last-minute changes to
   the spec (lightningdevkit#3017, lightningdevkit#3018).
 * CLN v24.02 requires the `gossip_queries` feature for all peers, however LDK
   by default does not set it for those not using a `P2PGossipSync` (e.g. those
   using RGS). This change was reverted in CLN v24.02.2 however for now LDK
   always sets the `gossip_queries` feature. This change is expected to be
   reverted in a future LDK release (lightningdevkit#2959).

Security
========
0.0.123 fixes a denial-of-service vulnerability which we believe to be reachable
from untrusted input when parsing invalid BOLT11 invoices containing non-ASCII
characters.
 * BOLT11 invoices with non-ASCII characters in the human-readable-part may
   cause an out-of-bounds read attempt leading to a panic (lightningdevkit#3054). Note that all
   BOLT11 invoices containing non-ASCII characters are invalid.

In total, this release features 150 files changed, 19307 insertions, 6306
deletions in 360 commits since 0.0.121 from 17 authors, in alphabetical order:

 * Arik Sosman
 * Duncan Dean
 * Elias Rohrer
 * Evan Feenstra
 * Jeffrey Czyz
 * Keyue Bao
 * Matt Corallo
 * Orbital
 * Sergi Delgado Segura
 * Valentine Wallace
 * Willem Van Lint
 * Wilmer Paulino
 * benthecarman
 * jbesraa
 * olegkubrakov
 * optout
 * shaavan
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Rethink default dust limit
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