- // Historically, the BOLTs were unclear if the message type
- // bytes should be included here or not. The BOLTs have now
- // been updated to indicate that they *are* included, but many
- // nodes still send messages without the type bytes, so we
- // support both here.
- // TODO: Switch to hard require the type prefix, as the current
- // permissiveness introduces the (although small) possibility
- // that we fail to decode legitimate channel updates that
- // happen to start with ChannelUpdate::TYPE, i.e., [0x01, 0x02].
- if update_slice.len() > 2
- && update_slice[0..2] == msgs::ChannelUpdate::TYPE.to_be_bytes()
- {
- update_slice = &update_slice[2..];
- } else {
- log_trace!(logger, "Failure provided features a channel update without type prefix. Deprecated, but allowing for now.");
- }
- let update_opt = msgs::ChannelUpdate::read(&mut Cursor::new(&update_slice));
- if update_opt.is_ok() || update_slice.is_empty() {
- // if channel_update should NOT have caused the failure:
- // MAY treat the channel_update as invalid.
- let is_chan_update_invalid = match error_code & 0xff {
- 7 => false,
- 11 => {
- update_opt.is_ok()
- && amt_to_forward
- > update_opt.as_ref().unwrap().contents.htlc_minimum_msat
- },
- 12 => {
- update_opt.is_ok()
- && amt_to_forward
- .checked_mul(
- update_opt
- .as_ref()
- .unwrap()
- .contents
- .fee_proportional_millionths as u64,
- )
- .map(|prop_fee| prop_fee / 1_000_000)
- .and_then(|prop_fee| {
- prop_fee.checked_add(
- update_opt.as_ref().unwrap().contents.fee_base_msat
- as u64,
- )
- })
- .map(|fee_msats| route_hop.fee_msat >= fee_msats)
- .unwrap_or(false)
- },
- 13 => {
- update_opt.is_ok()
- && route_hop.cltv_expiry_delta as u16
- >= update_opt.as_ref().unwrap().contents.cltv_expiry_delta
- },
- 14 => false, // expiry_too_soon; always valid?
- 20 => update_opt.as_ref().unwrap().contents.flags & 2 == 0,
- _ => false, // unknown error code; take channel_update as valid
- };
- if is_chan_update_invalid {
- // This probably indicates the node which forwarded
- // to the node in question corrupted something.
- network_update = Some(NetworkUpdate::ChannelFailure {
- short_channel_id: route_hop.short_channel_id,
- is_permanent: true,
- });
- } else {
- if let Ok(chan_update) = update_opt {
- // Make sure the ChannelUpdate contains the expected
- // short channel id.
- if failing_route_hop.short_channel_id
- == chan_update.contents.short_channel_id
- {
- short_channel_id = Some(failing_route_hop.short_channel_id);
- } else {
- log_info!(logger, "Node provided a channel_update for which it was not authoritative, ignoring.");
- }
- network_update =
- Some(NetworkUpdate::ChannelUpdateMessage { msg: chan_update })
- } else {
- // The node in question intentionally encoded a 0-length channel update. This is
- // likely due to https://github.com/ElementsProject/lightning/issues/6200.
- short_channel_id = Some(failing_route_hop.short_channel_id);
- network_update = Some(NetworkUpdate::ChannelFailure {
- short_channel_id: failing_route_hop.short_channel_id,
- is_permanent: false,
- });
- }
- };
- } else {
- // If the channel_update had a non-zero length (i.e. was
- // present) but we couldn't read it, treat it as a total
- // node failure.
- log_info!(
- logger,
- "Failed to read a channel_update of len {} in an onion",
- update_slice.len()
- );
- }