+ fn decode_update_add_htlc_onion(&self, msg: &msgs::UpdateAddHTLC) -> (PendingHTLCStatus, Option<SharedSecret>, MutexGuard<ChannelHolder>) {
+ macro_rules! get_onion_hash {
+ () => {
+ {
+ let mut sha = Sha256::new();
+ sha.input(&msg.onion_routing_packet.hop_data);
+ let mut onion_hash = [0; 32];
+ sha.result(&mut onion_hash);
+ onion_hash
+ }
+ }
+ }
+
+ if let Err(_) = msg.onion_routing_packet.public_key {
+ log_info!(self, "Failed to accept/forward incoming HTLC with invalid ephemeral pubkey");
+ return (PendingHTLCStatus::Fail(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
+ channel_id: msg.channel_id,
+ htlc_id: msg.htlc_id,
+ sha256_of_onion: get_onion_hash!(),
+ failure_code: 0x8000 | 0x4000 | 6,
+ })), None, self.channel_state.lock().unwrap());
+ }
+
+ let shared_secret = SharedSecret::new(&self.secp_ctx, &msg.onion_routing_packet.public_key.unwrap(), &self.our_network_key);
+ let (rho, mu) = ChannelManager::gen_rho_mu_from_shared_secret(&shared_secret);
+
+ let mut channel_state = None;
+ macro_rules! return_err {
+ ($msg: expr, $err_code: expr, $data: expr) => {
+ {
+ log_info!(self, "Failed to accept/forward incoming HTLC: {}", $msg);
+ if channel_state.is_none() {
+ channel_state = Some(self.channel_state.lock().unwrap());
+ }
+ return (PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
+ channel_id: msg.channel_id,
+ htlc_id: msg.htlc_id,
+ reason: ChannelManager::build_first_hop_failure_packet(&shared_secret, $err_code, $data),
+ })), Some(shared_secret), channel_state.unwrap());
+ }
+ }
+ }
+
+ if msg.onion_routing_packet.version != 0 {
+ //TODO: Spec doesn't indicate if we should only hash hop_data here (and in other
+ //sha256_of_onion error data packets), or the entire onion_routing_packet. Either way,
+ //the hash doesn't really serve any purpuse - in the case of hashing all data, the
+ //receiving node would have to brute force to figure out which version was put in the
+ //packet by the node that send us the message, in the case of hashing the hop_data, the
+ //node knows the HMAC matched, so they already know what is there...
+ return_err!("Unknown onion packet version", 0x8000 | 0x4000 | 4, &get_onion_hash!());
+ }
+
+ let mut hmac = Hmac::new(Sha256::new(), &mu);
+ hmac.input(&msg.onion_routing_packet.hop_data);
+ hmac.input(&msg.payment_hash);
+ if hmac.result() != MacResult::new(&msg.onion_routing_packet.hmac) {
+ return_err!("HMAC Check failed", 0x8000 | 0x4000 | 5, &get_onion_hash!());
+ }
+
+ let mut chacha = ChaCha20::new(&rho, &[0u8; 8]);
+ let next_hop_data = {
+ let mut decoded = [0; 65];
+ chacha.process(&msg.onion_routing_packet.hop_data[0..65], &mut decoded);
+ match msgs::OnionHopData::decode(&decoded[..]) {
+ Err(err) => {
+ let error_code = match err {
+ msgs::DecodeError::UnknownRealmByte => 0x4000 | 1,
+ _ => 0x2000 | 2, // Should never happen
+ };
+ return_err!("Unable to decode our hop data", error_code, &[0;0]);
+ },
+ Ok(msg) => msg
+ }
+ };
+
+ //TODO: Check that msg.cltv_expiry is within acceptable bounds!
+
+ let pending_forward_info = if next_hop_data.hmac == [0; 32] {
+ // OUR PAYMENT!
+ if next_hop_data.data.amt_to_forward != msg.amount_msat {
+ return_err!("Upstream node sent less than we were supposed to receive in payment", 19, &byte_utils::be64_to_array(msg.amount_msat));
+ }
+ if next_hop_data.data.outgoing_cltv_value != msg.cltv_expiry {
+ return_err!("Upstream node set CLTV to the wrong value", 18, &byte_utils::be32_to_array(msg.cltv_expiry));
+ }
+
+ // 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
+ // instead we stay symmetric with the forwarding case, only responding (after a
+ // delay) once they've send us a commitment_signed!
+
+ PendingHTLCStatus::Forward(PendingForwardHTLCInfo {
+ onion_packet: None,
+ payment_hash: msg.payment_hash.clone(),
+ short_channel_id: 0,
+ prev_short_channel_id: 0,
+ amt_to_forward: next_hop_data.data.amt_to_forward,
+ outgoing_cltv_value: next_hop_data.data.outgoing_cltv_value,
+ })
+ } else {
+ let mut new_packet_data = [0; 20*65];
+ chacha.process(&msg.onion_routing_packet.hop_data[65..], &mut new_packet_data[0..19*65]);
+ chacha.process(&ChannelManager::ZERO[0..65], &mut new_packet_data[19*65..]);
+
+ let mut new_pubkey = msg.onion_routing_packet.public_key.unwrap();
+
+ let blinding_factor = {
+ let mut sha = Sha256::new();
+ sha.input(&new_pubkey.serialize()[..]);
+ sha.input(&shared_secret[..]);
+ let mut res = [0u8; 32];
+ sha.result(&mut res);
+ match SecretKey::from_slice(&self.secp_ctx, &res) {
+ Err(_) => {
+ return_err!("Blinding factor is an invalid private key", 0x8000 | 0x4000 | 6, &get_onion_hash!());
+ },
+ Ok(key) => key
+ }
+ };
+
+ if let Err(_) = new_pubkey.mul_assign(&self.secp_ctx, &blinding_factor) {
+ return_err!("New blinding factor is an invalid private key", 0x8000 | 0x4000 | 6, &get_onion_hash!());
+ }
+
+ let outgoing_packet = msgs::OnionPacket {
+ version: 0,
+ public_key: Ok(new_pubkey),
+ hop_data: new_packet_data,
+ hmac: next_hop_data.hmac.clone(),
+ };
+
+ PendingHTLCStatus::Forward(PendingForwardHTLCInfo {
+ onion_packet: Some(outgoing_packet),
+ payment_hash: msg.payment_hash.clone(),
+ short_channel_id: next_hop_data.data.short_channel_id,
+ prev_short_channel_id: 0,
+ amt_to_forward: next_hop_data.data.amt_to_forward,
+ outgoing_cltv_value: next_hop_data.data.outgoing_cltv_value,
+ })
+ };
+
+ channel_state = Some(self.channel_state.lock().unwrap());
+ if let &PendingHTLCStatus::Forward(PendingForwardHTLCInfo { ref onion_packet, ref short_channel_id, ref amt_to_forward, ref outgoing_cltv_value, .. }) = &pending_forward_info {
+ if onion_packet.is_some() { // If short_channel_id is 0 here, we'll reject them in the body here
+ let id_option = channel_state.as_ref().unwrap().short_to_id.get(&short_channel_id).cloned();
+ let forwarding_id = match id_option {
+ None => {
+ return_err!("Don't have available channel for forwarding as requested.", 0x4000 | 10, &[0;0]);
+ },
+ Some(id) => id.clone(),
+ };
+ if let Some((err, code, chan_update)) = {
+ let chan = channel_state.as_mut().unwrap().by_id.get_mut(&forwarding_id).unwrap();
+ if !chan.is_live() {
+ Some(("Forwarding channel is not in a ready state.", 0x1000 | 7, self.get_channel_update(chan).unwrap()))
+ } else {
+ let fee = amt_to_forward.checked_mul(self.fee_proportional_millionths as u64).and_then(|prop_fee| { (prop_fee / 1000000).checked_add(chan.get_our_fee_base_msat(&*self.fee_estimator) as u64) });
+ if fee.is_none() || msg.amount_msat < fee.unwrap() || (msg.amount_msat - fee.unwrap()) < *amt_to_forward {
+ Some(("Prior hop has deviated from specified fees parameters or origin node has obsolete ones", 0x1000 | 12, self.get_channel_update(chan).unwrap()))
+ } else {
+ if (msg.cltv_expiry as u64) < (*outgoing_cltv_value) as u64 + CLTV_EXPIRY_DELTA as u64 {
+ Some(("Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta", 0x1000 | 13, self.get_channel_update(chan).unwrap()))
+ } else {
+ None
+ }
+ }
+ }
+ } {
+ return_err!(err, code, &chan_update.encode_with_len()[..]);
+ }
+ }
+ }
+
+ (pending_forward_info, Some(shared_secret), channel_state.unwrap())
+ }
+