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Move HTLCFailReason to onion_utils
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Now that it's entirely abstracted, there's no reason for
`HTLCFailReason` to be in `channelmanager`, it's really an
onion-level abstraction.
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@TheBlueMatt
TheBlueMatt committed Dec 1, 2022
1 parent 4ba8338 commit dabae73
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Showing 3 changed files with 89 additions and 87 deletions.
3 changes: 2 additions & 1 deletion lightning/src/ln/channel.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,9 +27,10 @@ use crate::ln::features::{ChannelTypeFeatures, InitFeatures};
use crate::ln::msgs;
use crate::ln::msgs::{DecodeError, OptionalField, DataLossProtect};
use crate::ln::script::{self, ShutdownScript};
use crate::ln::channelmanager::{self, CounterpartyForwardingInfo, PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA, MAX_LOCAL_BREAKDOWN_TIMEOUT};
use crate::ln::channelmanager::{self, CounterpartyForwardingInfo, PendingHTLCStatus, HTLCSource, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA, MAX_LOCAL_BREAKDOWN_TIMEOUT};
use crate::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, ClosingTransaction};
use crate::ln::chan_utils;
use crate::ln::onion_utils::HTLCFailReason;
use crate::chain::BestBlock;
use crate::chain::chaininterface::{FeeEstimator, ConfirmationTarget, LowerBoundedFeeEstimator};
use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, LATENCY_GRACE_PERIOD_BLOCKS};
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87 changes: 1 addition & 86 deletions lightning/src/ln/channelmanager.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,7 @@ use crate::ln::features::InvoiceFeatures;
use crate::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteHop, RoutePath, RouteParameters};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::HTLCFailReason;
use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError, MAX_VALUE_MSAT};
use crate::ln::wire::Encode;
use crate::chain::keysinterface::{Sign, KeysInterface, KeysManager, Recipient};
Expand Down Expand Up @@ -276,82 +277,6 @@ impl HTLCSource {
}
}

#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
pub(super) enum HTLCFailReason {
LightningError {
err: msgs::OnionErrorPacket,
},
Reason {
failure_code: u16,
data: Vec<u8>,
}
}

impl core::fmt::Debug for HTLCFailReason {
fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
match self {
HTLCFailReason::Reason { ref failure_code, .. } => {
write!(f, "HTLC error code {}", failure_code)
},
HTLCFailReason::LightningError { .. } => {
write!(f, "pre-built LightningError")
}
}
}
}

impl HTLCFailReason {
pub(super) fn reason(failure_code: u16, data: Vec<u8>) -> Self {
Self::Reason { failure_code, data }
}

pub(super) fn from_failure_code(failure_code: u16) -> Self {
Self::Reason { failure_code, data: Vec::new() }
}

pub(super) fn from_msg(msg: &msgs::UpdateFailHTLC) -> Self {
Self::LightningError { err: msg.reason.clone() }
}

fn get_encrypted_failure_packet(&self, incoming_packet_shared_secret: &[u8; 32], phantom_shared_secret: &Option<[u8; 32]>) -> msgs::OnionErrorPacket {
match self {
HTLCFailReason::Reason { ref failure_code, ref data } => {
if let Some(phantom_ss) = phantom_shared_secret {
let phantom_packet = onion_utils::build_failure_packet(phantom_ss, *failure_code, &data[..]).encode();
let encrypted_phantom_packet = onion_utils::encrypt_failure_packet(phantom_ss, &phantom_packet);
onion_utils::encrypt_failure_packet(incoming_packet_shared_secret, &encrypted_phantom_packet.data[..])
} else {
let packet = onion_utils::build_failure_packet(incoming_packet_shared_secret, *failure_code, &data[..]).encode();
onion_utils::encrypt_failure_packet(incoming_packet_shared_secret, &packet)
}
},
HTLCFailReason::LightningError { err } => {
onion_utils::encrypt_failure_packet(incoming_packet_shared_secret, &err.data)
}
}
}

fn decode_onion_failure<T: secp256k1::Signing, L: Deref>(&self, secp_ctx: &Secp256k1<T>, logger: &L, htlc_source: &HTLCSource) -> (Option<crate::routing::gossip::NetworkUpdate>, Option<u64>, bool, Option<u16>, Option<Vec<u8>>) where L::Target: Logger {
match self {
HTLCFailReason::LightningError { ref err } => {
onion_utils::process_onion_failure(secp_ctx, logger, &htlc_source, err.data.clone())
},
HTLCFailReason::Reason { ref failure_code, ref data, .. } => {
// we get a fail_malformed_htlc from the first hop
// TODO: We'd like to generate a NetworkUpdate for temporary
// failures here, but that would be insufficient as find_route
// generally ignores its view of our own channels as we provide them via
// ChannelDetails.
// TODO: For non-temporary failures, we really should be closing the
// channel here as we apparently can't relay through them anyway.
if let &HTLCSource::OutboundRoute { ref path, .. } = htlc_source {
(None, Some(path.first().unwrap().short_channel_id), true, Some(*failure_code), Some(data.clone()))
} else { unreachable!(); }
}
}
}
}

struct ReceiveError {
err_code: u16,
err_data: Vec<u8>,
Expand Down Expand Up @@ -7031,16 +6956,6 @@ impl Writeable for HTLCSource {
}
}

impl_writeable_tlv_based_enum!(HTLCFailReason,
(0, LightningError) => {
(0, err, required),
},
(1, Reason) => {
(0, failure_code, required),
(2, data, vec_type),
},
;);

impl_writeable_tlv_based!(PendingAddHTLCInfo, {
(0, forward_info, required),
(1, prev_user_channel_id, (default_value, 0)),
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86 changes: 86 additions & 0 deletions lightning/src/ln/onion_utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -592,6 +592,92 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(secp_ctx: &
} else { unreachable!(); }
}

#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
pub(super) enum HTLCFailReason {
LightningError {
err: msgs::OnionErrorPacket,
},
Reason {
failure_code: u16,
data: Vec<u8>,
}
}

impl core::fmt::Debug for HTLCFailReason {
fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
match self {
HTLCFailReason::Reason { ref failure_code, .. } => {
write!(f, "HTLC error code {}", failure_code)
},
HTLCFailReason::LightningError { .. } => {
write!(f, "pre-built LightningError")
}
}
}
}

impl_writeable_tlv_based_enum!(HTLCFailReason,
(0, LightningError) => {
(0, err, required),
},
(1, Reason) => {
(0, failure_code, required),
(2, data, vec_type),
},
;);

impl HTLCFailReason {
pub(super) fn reason(failure_code: u16, data: Vec<u8>) -> Self {
Self::Reason { failure_code, data }
}

pub(super) fn from_failure_code(failure_code: u16) -> Self {
Self::Reason { failure_code, data: Vec::new() }
}

pub(super) fn from_msg(msg: &msgs::UpdateFailHTLC) -> Self {
Self::LightningError { err: msg.reason.clone() }
}

pub(super) fn get_encrypted_failure_packet(&self, incoming_packet_shared_secret: &[u8; 32], phantom_shared_secret: &Option<[u8; 32]>) -> msgs::OnionErrorPacket {
match self {
HTLCFailReason::Reason { ref failure_code, ref data } => {
if let Some(phantom_ss) = phantom_shared_secret {
let phantom_packet = build_failure_packet(phantom_ss, *failure_code, &data[..]).encode();
let encrypted_phantom_packet = encrypt_failure_packet(phantom_ss, &phantom_packet);
encrypt_failure_packet(incoming_packet_shared_secret, &encrypted_phantom_packet.data[..])
} else {
let packet = build_failure_packet(incoming_packet_shared_secret, *failure_code, &data[..]).encode();
encrypt_failure_packet(incoming_packet_shared_secret, &packet)
}
},
HTLCFailReason::LightningError { err } => {
encrypt_failure_packet(incoming_packet_shared_secret, &err.data)
}
}
}

pub(super) fn decode_onion_failure<T: secp256k1::Signing, L: Deref>(&self, secp_ctx: &Secp256k1<T>, logger: &L, htlc_source: &HTLCSource) -> (Option<crate::routing::gossip::NetworkUpdate>, Option<u64>, bool, Option<u16>, Option<Vec<u8>>) where L::Target: Logger {
match self {
HTLCFailReason::LightningError { ref err } => {
process_onion_failure(secp_ctx, logger, &htlc_source, err.data.clone())
},
HTLCFailReason::Reason { ref failure_code, ref data, .. } => {
// we get a fail_malformed_htlc from the first hop
// TODO: We'd like to generate a NetworkUpdate for temporary
// failures here, but that would be insufficient as find_route
// generally ignores its view of our own channels as we provide them via
// ChannelDetails.
// TODO: For non-temporary failures, we really should be closing the
// channel here as we apparently can't relay through them anyway.
if let &HTLCSource::OutboundRoute { ref path, .. } = htlc_source {
(None, Some(path.first().unwrap().short_channel_id), true, Some(*failure_code), Some(data.clone()))
} else { unreachable!(); }
}
}
}
}

/// Allows `decode_next_hop` to return the next hop packet bytes for either payments or onion
/// message forwards.
pub(crate) trait NextPacketBytes: AsMut<[u8]> {
Expand Down

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