From dc61c9877378b359b7a074cea8751053d612a83c Mon Sep 17 00:00:00 2001 From: Yuntai Kyong Date: Sun, 14 Oct 2018 22:35:26 +0900 Subject: [PATCH] Partially implement more onion error handling for sent payments Also refactor out onion error handling into a function instead of in update_fail_htlc. Cache the initial htlc_msat that we sent instead of recalculating it to check validity of the error returned. --- src/ln/channelmanager.rs | 268 ++++++++++++++++++++++++++++++--------- 1 file changed, 211 insertions(+), 57 deletions(-) diff --git a/src/ln/channelmanager.rs b/src/ln/channelmanager.rs index ed86b511..7389a678 100644 --- a/src/ln/channelmanager.rs +++ b/src/ln/channelmanager.rs @@ -105,6 +105,9 @@ mod channel_held_info { OutboundRoute { route: Route, session_priv: SecretKey, + /// Technically we can recalculate this from the route, but we cache it here to avoid + /// doing a double-pass on route when we get a failure back + first_hop_htlc_msat: u64, }, } #[cfg(test)] @@ -113,6 +116,7 @@ mod channel_held_info { HTLCSource::OutboundRoute { route: Route { hops: Vec::new() }, session_priv: SecretKey::from_slice(&::secp256k1::Secp256k1::without_caps(), &[1; 32]).unwrap(), + first_hop_htlc_msat: 0, } } } @@ -1112,6 +1116,7 @@ impl ChannelManager { chan.send_htlc_and_commit(htlc_msat, payment_hash.clone(), htlc_cltv, HTLCSource::OutboundRoute { route: route.clone(), session_priv: session_priv.clone(), + first_hop_htlc_msat: htlc_msat, }, onion_packet).map_err(|he| APIError::ChannelUnavailable{err: he.err})? }; @@ -1794,6 +1799,203 @@ impl ChannelManager { Ok(()) } + // Process failure we got back from upstream on a payment we sent. Returns update and a boolean + // indicating that the payment itself failed + fn process_onion_failure(&self, htlc_source: &HTLCSource, mut packet_decrypted: Vec) -> (Option, bool) { + if let &HTLCSource::OutboundRoute { ref route, ref session_priv, ref first_hop_htlc_msat } = htlc_source { + macro_rules! onion_failure_log { + ( $error_code_textual: expr, $error_code: expr, $reported_name: expr, $reported_value: expr ) => { + log_trace!(self, "{}({:#x}) {}({})", $error_code_textual, $error_code, $reported_name, $reported_value); + }; + ( $error_code_textual: expr, $error_code: expr ) => { + log_trace!(self, "{}({})", $error_code_textual, $error_code); + }; + } + + const BADONION: u16 = 0x8000; + const PERM: u16 = 0x4000; + const UPDATE: u16 = 0x1000; + + let mut res = None; + let mut htlc_msat = *first_hop_htlc_msat; + + // Handle packed channel/node updates for passing back for the route handler + Self::construct_onion_keys_callback(&self.secp_ctx, route, session_priv, |shared_secret, _, _, route_hop| { + if res.is_some() { return; } + + let incoming_htlc_msat = htlc_msat; + let amt_to_forward = htlc_msat - route_hop.fee_msat; + htlc_msat = amt_to_forward; + + let ammag = ChannelManager::gen_ammag_from_shared_secret(&shared_secret); + + let mut decryption_tmp = Vec::with_capacity(packet_decrypted.len()); + decryption_tmp.resize(packet_decrypted.len(), 0); + let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]); + chacha.process(&packet_decrypted, &mut decryption_tmp[..]); + packet_decrypted = decryption_tmp; + + let is_from_final_node = route.hops.last().unwrap().pubkey == route_hop.pubkey; + + if let Ok(err_packet) = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&packet_decrypted)) { + let um = ChannelManager::gen_um_from_shared_secret(&shared_secret); + let mut hmac = Hmac::new(Sha256::new(), &um); + hmac.input(&err_packet.encode()[32..]); + let mut calc_tag = [0u8; 32]; + hmac.raw_result(&mut calc_tag); + + if crypto::util::fixed_time_eq(&calc_tag, &err_packet.hmac) { + if err_packet.failuremsg.len() < 2 { + // Useless packet that we can't use but it passed HMAC, so it + // definitely came from the peer in question + res = Some((None, !is_from_final_node)); + } else { + let error_code = byte_utils::slice_to_be16(&err_packet.failuremsg[0..2]); + + match error_code & 0xff { + 1|2|3 => { + // either from an intermediate or final node + // invalid_realm(PERM|1), + // temporary_node_failure(NODE|2) + // permanent_node_failure(PERM|NODE|2) + // required_node_feature_mssing(PERM|NODE|3) + res = Some((Some(msgs::HTLCFailChannelUpdate::NodeFailure { + node_id: route_hop.pubkey, + is_permanent: error_code & PERM == PERM, + }), !(error_code & PERM == PERM && is_from_final_node))); + // node returning invalid_realm is removed from network_map, + // although NODE flag is not set, TODO: or remove channel only? + // retry payment when removed node is not a final node + return; + }, + _ => {} + } + + if is_from_final_node { + let payment_retryable = match error_code { + c if c == PERM|15 => false, // unknown_payment_hash + c if c == PERM|16 => false, // incorrect_payment_amount + 17 => true, // final_expiry_too_soon + 18 if err_packet.failuremsg.len() == 6 => { // final_incorrect_cltv_expiry + let _reported_cltv_expiry = byte_utils::slice_to_be32(&err_packet.failuremsg[2..2+4]); + true + }, + 19 if err_packet.failuremsg.len() == 10 => { // final_incorrect_htlc_amount + let _reported_incoming_htlc_msat = byte_utils::slice_to_be64(&err_packet.failuremsg[2..2+8]); + true + }, + _ => { + // A final node has sent us either an invalid code or an error_code that + // MUST be sent from the processing node, or the formmat of failuremsg + // does not coform to the spec. + // Remove it from the network map and don't may retry payment + res = Some((Some(msgs::HTLCFailChannelUpdate::NodeFailure { + node_id: route_hop.pubkey, + is_permanent: true, + }), false)); + return; + } + }; + res = Some((None, payment_retryable)); + return; + } + + // now, error_code should be only from the intermediate nodes + match error_code { + _c if error_code & PERM == PERM => { + res = Some((Some(msgs::HTLCFailChannelUpdate::ChannelClosed { + short_channel_id: route_hop.short_channel_id, + is_permanent: true, + }), false)); + }, + _c if error_code & UPDATE == UPDATE => { + let offset = match error_code { + c if c == UPDATE|7 => 0, // temporary_channel_failure + c if c == UPDATE|11 => 8, // amount_below_minimum + c if c == UPDATE|12 => 8, // fee_insufficient + c if c == UPDATE|13 => 4, // incorrect_cltv_expiry + c if c == UPDATE|14 => 0, // expiry_too_soon + c if c == UPDATE|20 => 2, // channel_disabled + _ => { + // node sending unknown code + res = Some((Some(msgs::HTLCFailChannelUpdate::NodeFailure { + node_id: route_hop.pubkey, + is_permanent: true, + }), false)); + return; + } + }; + + if err_packet.failuremsg.len() >= offset + 2 { + let update_len = byte_utils::slice_to_be16(&err_packet.failuremsg[offset+2..offset+4]) as usize; + if err_packet.failuremsg.len() >= offset + 4 + update_len { + if let Ok(chan_update) = msgs::ChannelUpdate::read(&mut Cursor::new(&err_packet.failuremsg[offset + 4..offset + 4 + update_len])) { + // if channel_update should NOT have caused the failure: + // MAY treat the channel_update as invalid. + let is_chan_update_invalid = match error_code { + c if c == UPDATE|7 => { // temporary_channel_failure + false + }, + c if c == UPDATE|11 => { // amount_below_minimum + let reported_htlc_msat = byte_utils::slice_to_be64(&err_packet.failuremsg[2..2+8]); + onion_failure_log!("amount_below_minimum", UPDATE|11, "htlc_msat", reported_htlc_msat); + incoming_htlc_msat > chan_update.contents.htlc_minimum_msat + }, + c if c == UPDATE|12 => { // fee_insufficient + let reported_htlc_msat = byte_utils::slice_to_be64(&err_packet.failuremsg[2..2+8]); + let new_fee = amt_to_forward.checked_mul(chan_update.contents.fee_proportional_millionths as u64).and_then(|prop_fee| { (prop_fee / 1000000).checked_add(chan_update.contents.fee_base_msat as u64) }); + onion_failure_log!("fee_insufficient", UPDATE|12, "htlc_msat", reported_htlc_msat); + new_fee.is_none() || incoming_htlc_msat >= new_fee.unwrap() && incoming_htlc_msat >= amt_to_forward + new_fee.unwrap() + } + c if c == UPDATE|13 => { // incorrect_cltv_expiry + let reported_cltv_expiry = byte_utils::slice_to_be32(&err_packet.failuremsg[2..2+4]); + onion_failure_log!("incorrect_cltv_expiry", UPDATE|13, "cltv_expiry", reported_cltv_expiry); + route_hop.cltv_expiry_delta as u16 >= chan_update.contents.cltv_expiry_delta + }, + c if c == UPDATE|20 => { // channel_disabled + let reported_flags = byte_utils::slice_to_be16(&err_packet.failuremsg[2..2+2]); + onion_failure_log!("channel_disabled", UPDATE|20, "flags", reported_flags); + chan_update.contents.flags & 0x01 == 0x01 + }, + c if c == UPDATE|21 => true, // expiry_too_far + _ => { unreachable!(); }, + }; + + let msg = if is_chan_update_invalid { None } else { + Some(msgs::HTLCFailChannelUpdate::ChannelUpdateMessage { + msg: chan_update, + }) + }; + res = Some((msg, true)); + return; + } + } + } + }, + _c if error_code & BADONION == BADONION => { + //TODO + }, + 14 => { // expiry_too_soon + res = Some((None, true)); + return; + } + _ => { + // node sending unknown code + res = Some((Some(msgs::HTLCFailChannelUpdate::NodeFailure { + node_id: route_hop.pubkey, + is_permanent: true, + }), false)); + return; + } + } + } + } + } + }).expect("Route that we sent via spontaneously grew invalid keys in the middle of it?"); + res.unwrap_or((None, true)) + } else { ((None, true)) } + } + fn internal_update_fail_htlc(&self, their_node_id: &PublicKey, msg: &msgs::UpdateFailHTLC) -> Result, MsgHandleErrInternal> { let mut channel_state = self.channel_state.lock().unwrap(); let htlc_source = match channel_state.by_id.get_mut(&msg.channel_id) { @@ -1808,63 +2010,15 @@ impl ChannelManager { None => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel", msg.channel_id)) }?; - match htlc_source { - &HTLCSource::OutboundRoute { ref route, ref session_priv, .. } => { - // Handle packed channel/node updates for passing back for the route handler - let mut packet_decrypted = msg.reason.data.clone(); - let mut res = None; - Self::construct_onion_keys_callback(&self.secp_ctx, &route, &session_priv, |shared_secret, _, _, route_hop| { - if res.is_some() { return; } - - let ammag = ChannelManager::gen_ammag_from_shared_secret(&shared_secret); - - let mut decryption_tmp = Vec::with_capacity(packet_decrypted.len()); - decryption_tmp.resize(packet_decrypted.len(), 0); - let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]); - chacha.process(&packet_decrypted, &mut decryption_tmp[..]); - packet_decrypted = decryption_tmp; - - if let Ok(err_packet) = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&packet_decrypted)) { - if err_packet.failuremsg.len() >= 2 { - let um = ChannelManager::gen_um_from_shared_secret(&shared_secret); - - let mut hmac = Hmac::new(Sha256::new(), &um); - hmac.input(&err_packet.encode()[32..]); - let mut calc_tag = [0u8; 32]; - hmac.raw_result(&mut calc_tag); - if crypto::util::fixed_time_eq(&calc_tag, &err_packet.hmac) { - const UNKNOWN_CHAN: u16 = 0x4000|10; - const TEMP_CHAN_FAILURE: u16 = 0x4000|7; - match byte_utils::slice_to_be16(&err_packet.failuremsg[0..2]) { - TEMP_CHAN_FAILURE => { - if err_packet.failuremsg.len() >= 4 { - let update_len = byte_utils::slice_to_be16(&err_packet.failuremsg[2..4]) as usize; - if err_packet.failuremsg.len() >= 4 + update_len { - if let Ok(chan_update) = msgs::ChannelUpdate::read(&mut Cursor::new(&err_packet.failuremsg[4..4 + update_len])) { - res = Some(msgs::HTLCFailChannelUpdate::ChannelUpdateMessage { - msg: chan_update, - }); - } - } - } - }, - UNKNOWN_CHAN => { - // No such next-hop. We know this came from the - // current node as the HMAC validated. - res = Some(msgs::HTLCFailChannelUpdate::ChannelClosed { - short_channel_id: route_hop.short_channel_id, - is_permanent: true, - }); - }, - _ => {}, //TODO: Enumerate all of these! - } - } - } - } - }).unwrap(); - Ok(res) - }, - _ => { Ok(None) }, + // we are the origin node and update route information + // also determine if the payment is retryable + if let &HTLCSource::OutboundRoute { .. } = htlc_source { + let (channel_update, _payment_retry) = self.process_onion_failure(htlc_source, msg.reason.data.clone()); + Ok(channel_update) + // TODO: include pyament_retry info in PaymentFailed event that will be + // fired when receiving revoke_and_ack + } else { + Ok(None) } } -- 2.30.2