payment_hash: PaymentHash,
state: OutboundHTLCState,
source: HTLCSource,
+ skimmed_fee_msat: Option<u64>,
}
/// See AwaitingRemoteRevoke ChannelState for more info
payment_hash: PaymentHash,
source: HTLCSource,
onion_routing_packet: msgs::OnionPacket,
+ // The extra fee we're skimming off the top of this HTLC.
+ skimmed_fee_msat: Option<u64>,
},
ClaimHTLC {
payment_preimage: PaymentPreimage,
// handling this case better and maybe fulfilling some of the HTLCs while attempting
// to rebalance channels.
match &htlc_update {
- &HTLCUpdateAwaitingACK::AddHTLC {amount_msat, cltv_expiry, ref payment_hash, ref source, ref onion_routing_packet, ..} => {
- match self.send_htlc(amount_msat, *payment_hash, cltv_expiry, source.clone(), onion_routing_packet.clone(), false, logger) {
+ &HTLCUpdateAwaitingACK::AddHTLC {
+ amount_msat, cltv_expiry, ref payment_hash, ref source, ref onion_routing_packet,
+ skimmed_fee_msat, ..
+ } => {
+ match self.send_htlc(amount_msat, *payment_hash, cltv_expiry, source.clone(),
+ onion_routing_packet.clone(), false, skimmed_fee_msat, logger)
+ {
Ok(update_add_msg_option) => update_add_htlcs.push(update_add_msg_option.unwrap()),
Err(e) => {
match e {
payment_hash: htlc.payment_hash,
cltv_expiry: htlc.cltv_expiry,
onion_routing_packet: (**onion_packet).clone(),
+ skimmed_fee_msat: htlc.skimmed_fee_msat,
});
}
}
/// commitment update.
///
/// `Err`s will only be [`ChannelError::Ignore`].
- pub fn queue_add_htlc<L: Deref>(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource,
- onion_routing_packet: msgs::OnionPacket, logger: &L)
- -> Result<(), ChannelError> where L::Target: Logger {
+ pub fn queue_add_htlc<L: Deref>(
+ &mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource,
+ onion_routing_packet: msgs::OnionPacket, skimmed_fee_msat: Option<u64>, logger: &L
+ ) -> Result<(), ChannelError> where L::Target: Logger {
self
- .send_htlc(amount_msat, payment_hash, cltv_expiry, source, onion_routing_packet, true, logger)
+ .send_htlc(amount_msat, payment_hash, cltv_expiry, source, onion_routing_packet, true,
+ skimmed_fee_msat, logger)
.map(|msg_opt| assert!(msg_opt.is_none(), "We forced holding cell?"))
.map_err(|err| {
if let ChannelError::Ignore(_) = err { /* fine */ }
/// on this [`Channel`] if `force_holding_cell` is false.
///
/// `Err`s will only be [`ChannelError::Ignore`].
- fn send_htlc<L: Deref>(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource,
- onion_routing_packet: msgs::OnionPacket, mut force_holding_cell: bool, logger: &L)
- -> Result<Option<msgs::UpdateAddHTLC>, ChannelError> where L::Target: Logger {
+ fn send_htlc<L: Deref>(
+ &mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource,
+ onion_routing_packet: msgs::OnionPacket, mut force_holding_cell: bool,
+ skimmed_fee_msat: Option<u64>, logger: &L
+ ) -> Result<Option<msgs::UpdateAddHTLC>, ChannelError> where L::Target: Logger {
if (self.context.channel_state & (ChannelState::ChannelReady as u32 | BOTH_SIDES_SHUTDOWN_MASK)) != (ChannelState::ChannelReady as u32) {
return Err(ChannelError::Ignore("Cannot send HTLC until channel is fully established and we haven't started shutting down".to_owned()));
}
cltv_expiry,
source,
onion_routing_packet,
+ skimmed_fee_msat,
});
return Ok(None);
}
cltv_expiry,
state: OutboundHTLCState::LocalAnnounced(Box::new(onion_routing_packet.clone())),
source,
+ skimmed_fee_msat,
});
let res = msgs::UpdateAddHTLC {
payment_hash,
cltv_expiry,
onion_routing_packet,
+ skimmed_fee_msat,
};
self.context.next_holder_htlc_id += 1;
///
/// Shorthand for calling [`Self::send_htlc`] followed by a commitment update, see docs on
/// [`Self::send_htlc`] and [`Self::build_commitment_no_state_update`] for more info.
- pub fn send_htlc_and_commit<L: Deref>(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource, onion_routing_packet: msgs::OnionPacket, logger: &L) -> Result<Option<&ChannelMonitorUpdate>, ChannelError> where L::Target: Logger {
- let send_res = self.send_htlc(amount_msat, payment_hash, cltv_expiry, source, onion_routing_packet, false, logger);
+ pub fn send_htlc_and_commit<L: Deref>(
+ &mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource,
+ onion_routing_packet: msgs::OnionPacket, skimmed_fee_msat: Option<u64>, logger: &L
+ ) -> Result<Option<&ChannelMonitorUpdate>, ChannelError> where L::Target: Logger {
+ let send_res = self.send_htlc(amount_msat, payment_hash, cltv_expiry, source,
+ onion_routing_packet, false, skimmed_fee_msat, logger);
if let Err(e) = &send_res { if let ChannelError::Ignore(_) = e {} else { debug_assert!(false, "Sending cannot trigger channel failure"); } }
match send_res? {
Some(_) => {
}
let mut preimages: Vec<&Option<PaymentPreimage>> = vec![];
+ let mut pending_outbound_skimmed_fees: Vec<Option<u64>> = Vec::new();
(self.context.pending_outbound_htlcs.len() as u64).write(writer)?;
- for htlc in self.context.pending_outbound_htlcs.iter() {
+ for (idx, htlc) in self.context.pending_outbound_htlcs.iter().enumerate() {
htlc.htlc_id.write(writer)?;
htlc.amount_msat.write(writer)?;
htlc.cltv_expiry.write(writer)?;
reason.write(writer)?;
}
}
+ if let Some(skimmed_fee) = htlc.skimmed_fee_msat {
+ if pending_outbound_skimmed_fees.is_empty() {
+ for _ in 0..idx { pending_outbound_skimmed_fees.push(None); }
+ }
+ pending_outbound_skimmed_fees.push(Some(skimmed_fee));
+ } else if !pending_outbound_skimmed_fees.is_empty() {
+ pending_outbound_skimmed_fees.push(None);
+ }
}
+ let mut holding_cell_skimmed_fees: Vec<Option<u64>> = Vec::new();
(self.context.holding_cell_htlc_updates.len() as u64).write(writer)?;
- for update in self.context.holding_cell_htlc_updates.iter() {
+ for (idx, update) in self.context.holding_cell_htlc_updates.iter().enumerate() {
match update {
- &HTLCUpdateAwaitingACK::AddHTLC { ref amount_msat, ref cltv_expiry, ref payment_hash, ref source, ref onion_routing_packet } => {
+ &HTLCUpdateAwaitingACK::AddHTLC {
+ ref amount_msat, ref cltv_expiry, ref payment_hash, ref source, ref onion_routing_packet,
+ skimmed_fee_msat,
+ } => {
0u8.write(writer)?;
amount_msat.write(writer)?;
cltv_expiry.write(writer)?;
payment_hash.write(writer)?;
source.write(writer)?;
onion_routing_packet.write(writer)?;
+
+ if let Some(skimmed_fee) = skimmed_fee_msat {
+ if holding_cell_skimmed_fees.is_empty() {
+ for _ in 0..idx { holding_cell_skimmed_fees.push(None); }
+ }
+ holding_cell_skimmed_fees.push(Some(skimmed_fee));
+ } else if !holding_cell_skimmed_fees.is_empty() { holding_cell_skimmed_fees.push(None); }
},
&HTLCUpdateAwaitingACK::ClaimHTLC { ref payment_preimage, ref htlc_id } => {
1u8.write(writer)?;
(29, self.context.temporary_channel_id, option),
(31, channel_pending_event_emitted, option),
(33, self.context.pending_monitor_updates, vec_type),
+ (35, pending_outbound_skimmed_fees, optional_vec),
+ (37, holding_cell_skimmed_fees, optional_vec),
});
Ok(())
},
_ => return Err(DecodeError::InvalidValue),
},
+ skimmed_fee_msat: None,
});
}
payment_hash: Readable::read(reader)?,
source: Readable::read(reader)?,
onion_routing_packet: Readable::read(reader)?,
+ skimmed_fee_msat: None,
},
1 => HTLCUpdateAwaitingACK::ClaimHTLC {
payment_preimage: Readable::read(reader)?,
let mut pending_monitor_updates = Some(Vec::new());
+ let mut pending_outbound_skimmed_fees_opt: Option<Vec<Option<u64>>> = None;
+ let mut holding_cell_skimmed_fees_opt: Option<Vec<Option<u64>>> = None;
+
read_tlv_fields!(reader, {
(0, announcement_sigs, option),
(1, minimum_depth, option),
(29, temporary_channel_id, option),
(31, channel_pending_event_emitted, option),
(33, pending_monitor_updates, vec_type),
+ (35, pending_outbound_skimmed_fees_opt, optional_vec),
+ (37, holding_cell_skimmed_fees_opt, optional_vec),
});
let (channel_keys_id, holder_signer) = if let Some(channel_keys_id) = channel_keys_id {
let holder_max_accepted_htlcs = holder_max_accepted_htlcs.unwrap_or(DEFAULT_MAX_HTLCS);
+ if let Some(skimmed_fees) = pending_outbound_skimmed_fees_opt {
+ let mut iter = skimmed_fees.into_iter();
+ for htlc in pending_outbound_htlcs.iter_mut() {
+ htlc.skimmed_fee_msat = iter.next().ok_or(DecodeError::InvalidValue)?;
+ }
+ // We expect all skimmed fees to be consumed above
+ if iter.next().is_some() { return Err(DecodeError::InvalidValue) }
+ }
+ if let Some(skimmed_fees) = holding_cell_skimmed_fees_opt {
+ let mut iter = skimmed_fees.into_iter();
+ for htlc in holding_cell_htlc_updates.iter_mut() {
+ if let HTLCUpdateAwaitingACK::AddHTLC { ref mut skimmed_fee_msat, .. } = htlc {
+ *skimmed_fee_msat = iter.next().ok_or(DecodeError::InvalidValue)?;
+ }
+ }
+ // We expect all skimmed fees to be consumed above
+ if iter.next().is_some() { return Err(DecodeError::InvalidValue) }
+ }
+
Ok(Channel {
context: ChannelContext {
user_id,
session_priv: SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap(),
first_hop_htlc_msat: 548,
payment_id: PaymentId([42; 32]),
- }
+ },
+ skimmed_fee_msat: None,
});
// Make sure when Node A calculates their local commitment transaction, none of the HTLCs pass
payment_hash: PaymentHash([0; 32]),
state: OutboundHTLCState::Committed,
source: HTLCSource::dummy(),
+ skimmed_fee_msat: None,
};
out.payment_hash.0 = Sha256::hash(&hex::decode("0202020202020202020202020202020202020202020202020202020202020202").unwrap()).into_inner();
out
payment_hash: PaymentHash([0; 32]),
state: OutboundHTLCState::Committed,
source: HTLCSource::dummy(),
+ skimmed_fee_msat: None,
};
out.payment_hash.0 = Sha256::hash(&hex::decode("0303030303030303030303030303030303030303030303030303030303030303").unwrap()).into_inner();
out
payment_hash: PaymentHash([0; 32]),
state: OutboundHTLCState::Committed,
source: HTLCSource::dummy(),
+ skimmed_fee_msat: None,
};
out.payment_hash.0 = Sha256::hash(&hex::decode("0505050505050505050505050505050505050505050505050505050505050505").unwrap()).into_inner();
out
payment_hash: PaymentHash([0; 32]),
state: OutboundHTLCState::Committed,
source: HTLCSource::dummy(),
+ skimmed_fee_msat: None,
};
out.payment_hash.0 = Sha256::hash(&hex::decode("0505050505050505050505050505050505050505050505050505050505050505").unwrap()).into_inner();
out
/// may overshoot this in either case)
pub(super) outgoing_amt_msat: u64,
pub(super) outgoing_cltv_value: u32,
+ /// The fee being skimmed off the top of this HTLC. If this is a forward, it'll be the fee we are
+ /// skimming. If we're receiving this HTLC, it's the fee that our counterparty skimmed.
+ pub(super) skimmed_fee_msat: Option<u64>,
}
#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
total_value_received: Option<u64>,
/// The sender intended sum total of all MPP parts specified in the onion
total_msat: u64,
+ /// The extra fee our counterparty skimmed off the top of this HTLC.
+ counterparty_skimmed_fee_msat: Option<u64>,
}
/// A payment identifier used to uniquely identify a payment to LDK.
}
}
- fn construct_recv_pending_htlc_info(&self, hop_data: msgs::OnionHopData, shared_secret: [u8; 32],
- payment_hash: PaymentHash, amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>) -> Result<PendingHTLCInfo, ReceiveError>
- {
+ fn construct_recv_pending_htlc_info(
+ &self, hop_data: msgs::OnionHopData, shared_secret: [u8; 32], payment_hash: PaymentHash,
+ amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>, allow_underpay: bool,
+ counterparty_skimmed_fee_msat: Option<u64>,
+ ) -> Result<PendingHTLCInfo, ReceiveError> {
// final_incorrect_cltv_expiry
if hop_data.outgoing_cltv_value > cltv_expiry {
return Err(ReceiveError {
msg: "The final CLTV expiry is too soon to handle",
});
}
- if hop_data.amt_to_forward > amt_msat {
+ if (!allow_underpay && hop_data.amt_to_forward > amt_msat) ||
+ (allow_underpay && hop_data.amt_to_forward >
+ amt_msat.saturating_add(counterparty_skimmed_fee_msat.unwrap_or(0)))
+ {
return Err(ReceiveError {
err_code: 19,
err_data: amt_msat.to_be_bytes().to_vec(),
incoming_amt_msat: Some(amt_msat),
outgoing_amt_msat: hop_data.amt_to_forward,
outgoing_cltv_value: hop_data.outgoing_cltv_value,
+ skimmed_fee_msat: counterparty_skimmed_fee_msat,
})
}
- fn decode_update_add_htlc_onion(&self, msg: &msgs::UpdateAddHTLC) -> PendingHTLCStatus {
+ fn decode_update_add_htlc_onion(
+ &self, msg: &msgs::UpdateAddHTLC
+ ) -> Result<(onion_utils::Hop, [u8; 32], Option<Result<PublicKey, secp256k1::Error>>), HTLCFailureMsg> {
macro_rules! return_malformed_err {
($msg: expr, $err_code: expr) => {
{
log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
- return PendingHTLCStatus::Fail(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
+ return Err(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
channel_id: msg.channel_id,
htlc_id: msg.htlc_id,
sha256_of_onion: Sha256::hash(&msg.onion_routing_packet.hop_data).into_inner(),
($msg: expr, $err_code: expr, $data: expr) => {
{
log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
- return PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
+ return Err(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
channel_id: msg.channel_id,
htlc_id: msg.htlc_id,
reason: HTLCFailReason::reason($err_code, $data.to_vec())
return_err!(err_msg, err_code, &[0; 0]);
},
};
+ let (outgoing_scid, outgoing_amt_msat, outgoing_cltv_value, next_packet_pk_opt) = match next_hop {
+ onion_utils::Hop::Forward {
+ next_hop_data: msgs::OnionHopData {
+ format: msgs::OnionHopDataFormat::NonFinalNode { short_channel_id }, amt_to_forward,
+ outgoing_cltv_value,
+ }, ..
+ } => {
+ let next_pk = onion_utils::next_hop_packet_pubkey(&self.secp_ctx,
+ msg.onion_routing_packet.public_key.unwrap(), &shared_secret);
+ (short_channel_id, amt_to_forward, outgoing_cltv_value, Some(next_pk))
+ },
+ // We'll do receive checks in [`Self::construct_pending_htlc_info`] so we have access to the
+ // inbound channel's state.
+ onion_utils::Hop::Receive { .. } => return Ok((next_hop, shared_secret, None)),
+ onion_utils::Hop::Forward {
+ next_hop_data: msgs::OnionHopData { format: msgs::OnionHopDataFormat::FinalNode { .. }, .. }, ..
+ } => {
+ return_err!("Final Node OnionHopData provided for us as an intermediary node", 0x4000 | 22, &[0; 0]);
+ }
+ };
+
+ // Perform outbound checks here instead of in [`Self::construct_pending_htlc_info`] because we
+ // can't hold the outbound peer state lock at the same time as the inbound peer state lock.
+ if let Some((err, mut code, chan_update)) = loop {
+ let id_option = self.short_to_chan_info.read().unwrap().get(&outgoing_scid).cloned();
+ let forwarding_chan_info_opt = match id_option {
+ None => { // unknown_next_peer
+ // Note that this is likely a timing oracle for detecting whether an scid is a
+ // phantom or an intercept.
+ if (self.default_configuration.accept_intercept_htlcs &&
+ fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.genesis_hash)) ||
+ fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.genesis_hash)
+ {
+ None
+ } else {
+ break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
+ }
+ },
+ Some((cp_id, id)) => Some((cp_id.clone(), id.clone())),
+ };
+ let chan_update_opt = if let Some((counterparty_node_id, forwarding_id)) = forwarding_chan_info_opt {
+ let per_peer_state = self.per_peer_state.read().unwrap();
+ let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
+ if peer_state_mutex_opt.is_none() {
+ break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
+ }
+ let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+ let peer_state = &mut *peer_state_lock;
+ let chan = match peer_state.channel_by_id.get_mut(&forwarding_id) {
+ None => {
+ // Channel was removed. The short_to_chan_info and channel_by_id maps
+ // have no consistency guarantees.
+ break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
+ },
+ Some(chan) => chan
+ };
+ if !chan.context.should_announce() && !self.default_configuration.accept_forwards_to_priv_channels {
+ // Note that the behavior here should be identical to the above block - we
+ // should NOT reveal the existence or non-existence of a private channel if
+ // we don't allow forwards outbound over them.
+ break Some(("Refusing to forward to a private channel based on our config.", 0x4000 | 10, None));
+ }
+ if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
+ // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
+ // "refuse to forward unless the SCID alias was used", so we pretend
+ // we don't have the channel here.
+ break Some(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10, None));
+ }
+ let chan_update_opt = self.get_channel_update_for_onion(outgoing_scid, chan).ok();
+
+ // Note that we could technically not return an error yet here and just hope
+ // that the connection is reestablished or monitor updated by the time we get
+ // around to doing the actual forward, but better to fail early if we can and
+ // hopefully an attacker trying to path-trace payments cannot make this occur
+ // on a small/per-node/per-channel scale.
+ if !chan.context.is_live() { // channel_disabled
+ // If the channel_update we're going to return is disabled (i.e. the
+ // peer has been disabled for some time), return `channel_disabled`,
+ // otherwise return `temporary_channel_failure`.
+ if chan_update_opt.as_ref().map(|u| u.contents.flags & 2 == 2).unwrap_or(false) {
+ break Some(("Forwarding channel has been disconnected for some time.", 0x1000 | 20, chan_update_opt));
+ } else {
+ break Some(("Forwarding channel is not in a ready state.", 0x1000 | 7, chan_update_opt));
+ }
+ }
+ if outgoing_amt_msat < chan.context.get_counterparty_htlc_minimum_msat() { // amount_below_minimum
+ break Some(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, chan_update_opt));
+ }
+ if let Err((err, code)) = chan.htlc_satisfies_config(&msg, outgoing_amt_msat, outgoing_cltv_value) {
+ break Some((err, code, chan_update_opt));
+ }
+ chan_update_opt
+ } else {
+ if (msg.cltv_expiry as u64) < (outgoing_cltv_value) as u64 + MIN_CLTV_EXPIRY_DELTA as u64 {
+ // We really should set `incorrect_cltv_expiry` here but as we're not
+ // forwarding over a real channel we can't generate a channel_update
+ // for it. Instead we just return a generic temporary_node_failure.
+ break Some((
+ "Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta",
+ 0x2000 | 2, None,
+ ));
+ }
+ None
+ };
+
+ let cur_height = self.best_block.read().unwrap().height() + 1;
+ // Theoretically, channel counterparty shouldn't send us a HTLC expiring now,
+ // but we want to be robust wrt to counterparty packet sanitization (see
+ // HTLC_FAIL_BACK_BUFFER rationale).
+ if msg.cltv_expiry <= cur_height + HTLC_FAIL_BACK_BUFFER as u32 { // expiry_too_soon
+ break Some(("CLTV expiry is too close", 0x1000 | 14, chan_update_opt));
+ }
+ if msg.cltv_expiry > cur_height + CLTV_FAR_FAR_AWAY as u32 { // expiry_too_far
+ break Some(("CLTV expiry is too far in the future", 21, None));
+ }
+ // If the HTLC expires ~now, don't bother trying to forward it to our
+ // counterparty. They should fail it anyway, but we don't want to bother with
+ // the round-trips or risk them deciding they definitely want the HTLC and
+ // force-closing to ensure they get it if we're offline.
+ // We previously had a much more aggressive check here which tried to ensure
+ // our counterparty receives an HTLC which has *our* risk threshold met on it,
+ // but there is no need to do that, and since we're a bit conservative with our
+ // risk threshold it just results in failing to forward payments.
+ if (outgoing_cltv_value) as u64 <= (cur_height + LATENCY_GRACE_PERIOD_BLOCKS) as u64 {
+ break Some(("Outgoing CLTV value is too soon", 0x1000 | 14, chan_update_opt));
+ }
+
+ break None;
+ }
+ {
+ let mut res = VecWriter(Vec::with_capacity(chan_update.serialized_length() + 2 + 8 + 2));
+ if let Some(chan_update) = chan_update {
+ if code == 0x1000 | 11 || code == 0x1000 | 12 {
+ msg.amount_msat.write(&mut res).expect("Writes cannot fail");
+ }
+ else if code == 0x1000 | 13 {
+ msg.cltv_expiry.write(&mut res).expect("Writes cannot fail");
+ }
+ else if code == 0x1000 | 20 {
+ // TODO: underspecified, follow https://github.com/lightning/bolts/issues/791
+ 0u16.write(&mut res).expect("Writes cannot fail");
+ }
+ (chan_update.serialized_length() as u16 + 2).write(&mut res).expect("Writes cannot fail");
+ msgs::ChannelUpdate::TYPE.write(&mut res).expect("Writes cannot fail");
+ chan_update.write(&mut res).expect("Writes cannot fail");
+ } else if code & 0x1000 == 0x1000 {
+ // If we're trying to return an error that requires a `channel_update` but
+ // we're forwarding to a phantom or intercept "channel" (i.e. cannot
+ // generate an update), just use the generic "temporary_node_failure"
+ // instead.
+ code = 0x2000 | 2;
+ }
+ return_err!(err, code, &res.0[..]);
+ }
+ Ok((next_hop, shared_secret, next_packet_pk_opt))
+ }
- let pending_forward_info = match next_hop {
+ fn construct_pending_htlc_status<'a>(
+ &self, msg: &msgs::UpdateAddHTLC, shared_secret: [u8; 32], decoded_hop: onion_utils::Hop,
+ allow_underpay: bool, next_packet_pubkey_opt: Option<Result<PublicKey, secp256k1::Error>>
+ ) -> PendingHTLCStatus {
+ macro_rules! return_err {
+ ($msg: expr, $err_code: expr, $data: expr) => {
+ {
+ log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
+ return PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
+ channel_id: msg.channel_id,
+ htlc_id: msg.htlc_id,
+ reason: HTLCFailReason::reason($err_code, $data.to_vec())
+ .get_encrypted_failure_packet(&shared_secret, &None),
+ }));
+ }
+ }
+ }
+ match decoded_hop {
onion_utils::Hop::Receive(next_hop_data) => {
// OUR PAYMENT!
- match self.construct_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash, msg.amount_msat, msg.cltv_expiry, None) {
+ match self.construct_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash,
+ msg.amount_msat, msg.cltv_expiry, None, allow_underpay, msg.skimmed_fee_msat)
+ {
Ok(info) => {
// Note that we could obviously respond immediately with an update_fulfill_htlc
// message, however that would leak that we are the recipient of this payment, so
}
},
onion_utils::Hop::Forward { next_hop_data, next_hop_hmac, new_packet_bytes } => {
- let new_pubkey = msg.onion_routing_packet.public_key.unwrap();
+ debug_assert!(next_packet_pubkey_opt.is_some());
let outgoing_packet = msgs::OnionPacket {
version: 0,
- public_key: onion_utils::next_hop_packet_pubkey(&self.secp_ctx, new_pubkey, &shared_secret),
+ public_key: next_packet_pubkey_opt.unwrap_or(Err(secp256k1::Error::InvalidPublicKey)),
hop_data: new_packet_bytes,
hmac: next_hop_hmac.clone(),
};
incoming_amt_msat: Some(msg.amount_msat),
outgoing_amt_msat: next_hop_data.amt_to_forward,
outgoing_cltv_value: next_hop_data.outgoing_cltv_value,
+ skimmed_fee_msat: None,
})
}
- };
-
- if let &PendingHTLCStatus::Forward(PendingHTLCInfo { ref routing, ref outgoing_amt_msat, ref outgoing_cltv_value, .. }) = &pending_forward_info {
- // If short_channel_id is 0 here, we'll reject the HTLC as there cannot be a channel
- // with a short_channel_id of 0. This is important as various things later assume
- // short_channel_id is non-0 in any ::Forward.
- if let &PendingHTLCRouting::Forward { ref short_channel_id, .. } = routing {
- if let Some((err, mut code, chan_update)) = loop {
- let id_option = self.short_to_chan_info.read().unwrap().get(short_channel_id).cloned();
- let forwarding_chan_info_opt = match id_option {
- None => { // unknown_next_peer
- // Note that this is likely a timing oracle for detecting whether an scid is a
- // phantom or an intercept.
- if (self.default_configuration.accept_intercept_htlcs &&
- fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, *short_channel_id, &self.genesis_hash)) ||
- fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, *short_channel_id, &self.genesis_hash)
- {
- None
- } else {
- break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
- }
- },
- Some((cp_id, id)) => Some((cp_id.clone(), id.clone())),
- };
- let chan_update_opt = if let Some((counterparty_node_id, forwarding_id)) = forwarding_chan_info_opt {
- let per_peer_state = self.per_peer_state.read().unwrap();
- let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
- if peer_state_mutex_opt.is_none() {
- break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
- }
- let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
- let peer_state = &mut *peer_state_lock;
- let chan = match peer_state.channel_by_id.get_mut(&forwarding_id) {
- None => {
- // Channel was removed. The short_to_chan_info and channel_by_id maps
- // have no consistency guarantees.
- break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
- },
- Some(chan) => chan
- };
- if !chan.context.should_announce() && !self.default_configuration.accept_forwards_to_priv_channels {
- // Note that the behavior here should be identical to the above block - we
- // should NOT reveal the existence or non-existence of a private channel if
- // we don't allow forwards outbound over them.
- break Some(("Refusing to forward to a private channel based on our config.", 0x4000 | 10, None));
- }
- if chan.context.get_channel_type().supports_scid_privacy() && *short_channel_id != chan.context.outbound_scid_alias() {
- // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
- // "refuse to forward unless the SCID alias was used", so we pretend
- // we don't have the channel here.
- break Some(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10, None));
- }
- let chan_update_opt = self.get_channel_update_for_onion(*short_channel_id, chan).ok();
-
- // Note that we could technically not return an error yet here and just hope
- // that the connection is reestablished or monitor updated by the time we get
- // around to doing the actual forward, but better to fail early if we can and
- // hopefully an attacker trying to path-trace payments cannot make this occur
- // on a small/per-node/per-channel scale.
- if !chan.context.is_live() { // channel_disabled
- // If the channel_update we're going to return is disabled (i.e. the
- // peer has been disabled for some time), return `channel_disabled`,
- // otherwise return `temporary_channel_failure`.
- if chan_update_opt.as_ref().map(|u| u.contents.flags & 2 == 2).unwrap_or(false) {
- break Some(("Forwarding channel has been disconnected for some time.", 0x1000 | 20, chan_update_opt));
- } else {
- break Some(("Forwarding channel is not in a ready state.", 0x1000 | 7, chan_update_opt));
- }
- }
- if *outgoing_amt_msat < chan.context.get_counterparty_htlc_minimum_msat() { // amount_below_minimum
- break Some(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, chan_update_opt));
- }
- if let Err((err, code)) = chan.htlc_satisfies_config(&msg, *outgoing_amt_msat, *outgoing_cltv_value) {
- break Some((err, code, chan_update_opt));
- }
- chan_update_opt
- } else {
- if (msg.cltv_expiry as u64) < (*outgoing_cltv_value) as u64 + MIN_CLTV_EXPIRY_DELTA as u64 {
- // We really should set `incorrect_cltv_expiry` here but as we're not
- // forwarding over a real channel we can't generate a channel_update
- // for it. Instead we just return a generic temporary_node_failure.
- break Some((
- "Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta",
- 0x2000 | 2, None,
- ));
- }
- None
- };
-
- let cur_height = self.best_block.read().unwrap().height() + 1;
- // Theoretically, channel counterparty shouldn't send us a HTLC expiring now,
- // but we want to be robust wrt to counterparty packet sanitization (see
- // HTLC_FAIL_BACK_BUFFER rationale).
- if msg.cltv_expiry <= cur_height + HTLC_FAIL_BACK_BUFFER as u32 { // expiry_too_soon
- break Some(("CLTV expiry is too close", 0x1000 | 14, chan_update_opt));
- }
- if msg.cltv_expiry > cur_height + CLTV_FAR_FAR_AWAY as u32 { // expiry_too_far
- break Some(("CLTV expiry is too far in the future", 21, None));
- }
- // If the HTLC expires ~now, don't bother trying to forward it to our
- // counterparty. They should fail it anyway, but we don't want to bother with
- // the round-trips or risk them deciding they definitely want the HTLC and
- // force-closing to ensure they get it if we're offline.
- // We previously had a much more aggressive check here which tried to ensure
- // our counterparty receives an HTLC which has *our* risk threshold met on it,
- // but there is no need to do that, and since we're a bit conservative with our
- // risk threshold it just results in failing to forward payments.
- if (*outgoing_cltv_value) as u64 <= (cur_height + LATENCY_GRACE_PERIOD_BLOCKS) as u64 {
- break Some(("Outgoing CLTV value is too soon", 0x1000 | 14, chan_update_opt));
- }
-
- break None;
- }
- {
- let mut res = VecWriter(Vec::with_capacity(chan_update.serialized_length() + 2 + 8 + 2));
- if let Some(chan_update) = chan_update {
- if code == 0x1000 | 11 || code == 0x1000 | 12 {
- msg.amount_msat.write(&mut res).expect("Writes cannot fail");
- }
- else if code == 0x1000 | 13 {
- msg.cltv_expiry.write(&mut res).expect("Writes cannot fail");
- }
- else if code == 0x1000 | 20 {
- // TODO: underspecified, follow https://github.com/lightning/bolts/issues/791
- 0u16.write(&mut res).expect("Writes cannot fail");
- }
- (chan_update.serialized_length() as u16 + 2).write(&mut res).expect("Writes cannot fail");
- msgs::ChannelUpdate::TYPE.write(&mut res).expect("Writes cannot fail");
- chan_update.write(&mut res).expect("Writes cannot fail");
- } else if code & 0x1000 == 0x1000 {
- // If we're trying to return an error that requires a `channel_update` but
- // we're forwarding to a phantom or intercept "channel" (i.e. cannot
- // generate an update), just use the generic "temporary_node_failure"
- // instead.
- code = 0x2000 | 2;
- }
- return_err!(err, code, &res.0[..]);
- }
- }
}
-
- pending_forward_info
}
/// Gets the current [`channel_update`] for the given channel. This first checks if the channel is
session_priv: session_priv.clone(),
first_hop_htlc_msat: htlc_msat,
payment_id,
- }, onion_packet, &self.logger);
+ }, onion_packet, None, &self.logger);
match break_chan_entry!(self, send_res, chan) {
Some(monitor_update) => {
let update_id = monitor_update.update_id;
/// [`ChannelManager::fail_intercepted_htlc`] MUST be called in response to the event.
///
/// Note that LDK does not enforce fee requirements in `amt_to_forward_msat`, and will not stop
- /// you from forwarding more than you received.
+ /// you from forwarding more than you received. See
+ /// [`HTLCIntercepted::expected_outbound_amount_msat`] for more on forwarding a different amount
+ /// than expected.
///
/// Errors if the event was not handled in time, in which case the HTLC was automatically failed
/// backwards.
///
/// [`UserConfig::accept_intercept_htlcs`]: crate::util::config::UserConfig::accept_intercept_htlcs
/// [`HTLCIntercepted`]: events::Event::HTLCIntercepted
+ /// [`HTLCIntercepted::expected_outbound_amount_msat`]: events::Event::HTLCIntercepted::expected_outbound_amount_msat
// TODO: when we move to deciding the best outbound channel at forward time, only take
// `next_node_id` and not `next_hop_channel_id`
pub fn forward_intercepted_htlc(&self, intercept_id: InterceptId, next_hop_channel_id: &[u8; 32], next_node_id: PublicKey, amt_to_forward_msat: u64) -> Result<(), APIError> {
},
_ => unreachable!() // Only `PendingHTLCRouting::Forward`s are intercepted
};
+ let skimmed_fee_msat =
+ payment.forward_info.outgoing_amt_msat.saturating_sub(amt_to_forward_msat);
let pending_htlc_info = PendingHTLCInfo {
+ skimmed_fee_msat: if skimmed_fee_msat == 0 { None } else { Some(skimmed_fee_msat) },
outgoing_amt_msat: amt_to_forward_msat, routing, ..payment.forward_info
};
prev_short_channel_id, prev_htlc_id, prev_funding_outpoint, prev_user_channel_id,
forward_info: PendingHTLCInfo {
routing, incoming_shared_secret, payment_hash, outgoing_amt_msat,
- outgoing_cltv_value, incoming_amt_msat: _
+ outgoing_cltv_value, ..
}
}) => {
macro_rules! failure_handler {
};
match next_hop {
onion_utils::Hop::Receive(hop_data) => {
- match self.construct_recv_pending_htlc_info(hop_data, incoming_shared_secret, payment_hash, outgoing_amt_msat, outgoing_cltv_value, Some(phantom_shared_secret)) {
+ match self.construct_recv_pending_htlc_info(hop_data,
+ incoming_shared_secret, payment_hash, outgoing_amt_msat,
+ outgoing_cltv_value, Some(phantom_shared_secret), false, None)
+ {
Ok(info) => phantom_receives.push((prev_short_channel_id, prev_funding_outpoint, prev_user_channel_id, vec![(info, prev_htlc_id)])),
Err(ReceiveError { err_code, err_data, msg }) => failed_payment!(msg, err_code, err_data, Some(phantom_shared_secret))
}
prev_short_channel_id, prev_htlc_id, prev_funding_outpoint, prev_user_channel_id: _,
forward_info: PendingHTLCInfo {
incoming_shared_secret, payment_hash, outgoing_amt_msat, outgoing_cltv_value,
- routing: PendingHTLCRouting::Forward { onion_packet, .. }, incoming_amt_msat: _,
+ routing: PendingHTLCRouting::Forward { onion_packet, .. }, skimmed_fee_msat, ..
},
}) => {
log_trace!(self.logger, "Adding HTLC from short id {} with payment_hash {} to channel with short id {} after delay", prev_short_channel_id, log_bytes!(payment_hash.0), short_chan_id);
});
if let Err(e) = chan.get_mut().queue_add_htlc(outgoing_amt_msat,
payment_hash, outgoing_cltv_value, htlc_source.clone(),
- onion_packet, &self.logger)
+ onion_packet, skimmed_fee_msat, &self.logger)
{
if let ChannelError::Ignore(msg) = e {
log_trace!(self.logger, "Failed to forward HTLC with payment_hash {}: {}", log_bytes!(payment_hash.0), msg);
HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
prev_short_channel_id, prev_htlc_id, prev_funding_outpoint, prev_user_channel_id,
forward_info: PendingHTLCInfo {
- routing, incoming_shared_secret, payment_hash, incoming_amt_msat, outgoing_amt_msat, ..
+ routing, incoming_shared_secret, payment_hash, incoming_amt_msat, outgoing_amt_msat,
+ skimmed_fee_msat, ..
}
}) => {
let (cltv_expiry, onion_payload, payment_data, phantom_shared_secret, mut onion_fields) = match routing {
total_msat: if let Some(data) = &payment_data { data.total_msat } else { outgoing_amt_msat },
cltv_expiry,
onion_payload,
+ counterparty_skimmed_fee_msat: skimmed_fee_msat,
};
let mut committed_to_claimable = false;
htlcs.push(claimable_htlc);
let amount_msat = htlcs.iter().map(|htlc| htlc.value).sum();
htlcs.iter_mut().for_each(|htlc| htlc.total_value_received = Some(amount_msat));
+ let counterparty_skimmed_fee_msat = htlcs.iter()
+ .map(|htlc| htlc.counterparty_skimmed_fee_msat.unwrap_or(0)).sum();
+ debug_assert!(total_value.saturating_sub(amount_msat) <=
+ counterparty_skimmed_fee_msat);
new_events.push_back((events::Event::PaymentClaimable {
receiver_node_id: Some(receiver_node_id),
payment_hash,
purpose: $purpose,
amount_msat,
+ counterparty_skimmed_fee_msat,
via_channel_id: Some(prev_channel_id),
via_user_channel_id: Some(prev_user_channel_id),
claim_deadline: Some(earliest_expiry - HTLC_FAIL_BACK_BUFFER),
//encrypted with the same key. It's not immediately obvious how to usefully exploit that,
//but we should prevent it anyway.
- let pending_forward_info = self.decode_update_add_htlc_onion(msg);
+ let decoded_hop_res = self.decode_update_add_htlc_onion(msg);
let per_peer_state = self.per_peer_state.read().unwrap();
let peer_state_mutex = per_peer_state.get(counterparty_node_id)
.ok_or_else(|| {
match peer_state.channel_by_id.entry(msg.channel_id) {
hash_map::Entry::Occupied(mut chan) => {
+ let pending_forward_info = match decoded_hop_res {
+ Ok((next_hop, shared_secret, next_packet_pk_opt)) =>
+ self.construct_pending_htlc_status(msg, shared_secret, next_hop,
+ chan.get().context.config().accept_underpaying_htlcs, next_packet_pk_opt),
+ Err(e) => PendingHTLCStatus::Fail(e)
+ };
let create_pending_htlc_status = |chan: &Channel<<SP::Target as SignerProvider>::Signer>, pending_forward_info: PendingHTLCStatus, error_code: u16| {
// If the update_add is completely bogus, the call will Err and we will close,
// but if we've sent a shutdown and they haven't acknowledged it yet, we just
(6, outgoing_amt_msat, required),
(8, outgoing_cltv_value, required),
(9, incoming_amt_msat, option),
+ (10, skimmed_fee_msat, option),
});
(5, self.total_value_received, option),
(6, self.cltv_expiry, required),
(8, keysend_preimage, option),
+ (10, self.counterparty_skimmed_fee_msat, option),
});
Ok(())
}
impl Readable for ClaimableHTLC {
fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
- let mut prev_hop = crate::util::ser::RequiredWrapper(None);
- let mut value = 0;
- let mut sender_intended_value = None;
- let mut payment_data: Option<msgs::FinalOnionHopData> = None;
- let mut cltv_expiry = 0;
- let mut total_value_received = None;
- let mut total_msat = None;
- let mut keysend_preimage: Option<PaymentPreimage> = None;
- read_tlv_fields!(reader, {
+ _init_and_read_tlv_fields!(reader, {
(0, prev_hop, required),
(1, total_msat, option),
- (2, value, required),
+ (2, value_ser, required),
(3, sender_intended_value, option),
- (4, payment_data, option),
+ (4, payment_data_opt, option),
(5, total_value_received, option),
(6, cltv_expiry, required),
- (8, keysend_preimage, option)
+ (8, keysend_preimage, option),
+ (10, counterparty_skimmed_fee_msat, option),
});
+ let payment_data: Option<msgs::FinalOnionHopData> = payment_data_opt;
+ let value = value_ser.0.unwrap();
let onion_payload = match keysend_preimage {
Some(p) => {
if payment_data.is_some() {
total_value_received,
total_msat: total_msat.unwrap(),
onion_payload,
- cltv_expiry,
+ cltv_expiry: cltv_expiry.0.unwrap(),
+ counterparty_skimmed_fee_msat,
})
}
}
get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, last_random_pk);
}
+ #[test]
+ fn reject_excessively_underpaying_htlcs() {
+ let chanmon_cfg = create_chanmon_cfgs(1);
+ let node_cfg = create_node_cfgs(1, &chanmon_cfg);
+ let node_chanmgr = create_node_chanmgrs(1, &node_cfg, &[None]);
+ let node = create_network(1, &node_cfg, &node_chanmgr);
+ let sender_intended_amt_msat = 100;
+ let extra_fee_msat = 10;
+ let hop_data = msgs::OnionHopData {
+ amt_to_forward: 100,
+ outgoing_cltv_value: 42,
+ format: msgs::OnionHopDataFormat::FinalNode {
+ keysend_preimage: None,
+ payment_metadata: None,
+ payment_data: Some(msgs::FinalOnionHopData {
+ payment_secret: PaymentSecret([0; 32]), total_msat: sender_intended_amt_msat,
+ }),
+ }
+ };
+ // Check that if the amount we received + the penultimate hop extra fee is less than the sender
+ // intended amount, we fail the payment.
+ if let Err(crate::ln::channelmanager::ReceiveError { err_code, .. }) =
+ node[0].node.construct_recv_pending_htlc_info(hop_data, [0; 32], PaymentHash([0; 32]),
+ sender_intended_amt_msat - extra_fee_msat - 1, 42, None, true, Some(extra_fee_msat))
+ {
+ assert_eq!(err_code, 19);
+ } else { panic!(); }
+
+ // If amt_received + extra_fee is equal to the sender intended amount, we're fine.
+ let hop_data = msgs::OnionHopData { // This is the same hop_data as above, OnionHopData doesn't implement Clone
+ amt_to_forward: 100,
+ outgoing_cltv_value: 42,
+ format: msgs::OnionHopDataFormat::FinalNode {
+ keysend_preimage: None,
+ payment_metadata: None,
+ payment_data: Some(msgs::FinalOnionHopData {
+ payment_secret: PaymentSecret([0; 32]), total_msat: sender_intended_amt_msat,
+ }),
+ }
+ };
+ assert!(node[0].node.construct_recv_pending_htlc_info(hop_data, [0; 32], PaymentHash([0; 32]),
+ sender_intended_amt_msat - extra_fee_msat, 42, None, true, Some(extra_fee_msat)).is_ok());
+ }
+
#[cfg(anchors)]
#[test]
fn test_anchors_zero_fee_htlc_tx_fallback() {
projects / rust-lightning / commitdiff