Merge pull request #1324 from valentinewallace/2022-02-phantom-followup
[rust-lightning] / lightning / src / ln / channelmanager.rs
index b47caa6aec42d10b54e2526c64c64699b6a11dd7..674977faaebc2ecd519682ea8f5edb17589fc81b 100644 (file)
@@ -358,7 +358,7 @@ mod inbound_payment {
 // our payment, which we can use to decode errors or inform the user that the payment was sent.
 
 #[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
-enum PendingHTLCRouting {
+pub(super) enum PendingHTLCRouting {
        Forward {
                onion_packet: msgs::OnionPacket,
                short_channel_id: u64, // This should be NonZero<u64> eventually when we bump MSRV
@@ -366,6 +366,7 @@ enum PendingHTLCRouting {
        Receive {
                payment_data: msgs::FinalOnionHopData,
                incoming_cltv_expiry: u32, // Used to track when we should expire pending HTLCs that go unclaimed
+               phantom_shared_secret: Option<[u8; 32]>,
        },
        ReceiveKeysend {
                payment_preimage: PaymentPreimage,
@@ -375,8 +376,8 @@ enum PendingHTLCRouting {
 
 #[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
 pub(super) struct PendingHTLCInfo {
-       routing: PendingHTLCRouting,
-       incoming_shared_secret: [u8; 32],
+       pub(super) routing: PendingHTLCRouting,
+       pub(super) incoming_shared_secret: [u8; 32],
        payment_hash: PaymentHash,
        pub(super) amt_to_forward: u64,
        pub(super) outgoing_cltv_value: u32,
@@ -419,6 +420,7 @@ pub(crate) struct HTLCPreviousHopData {
        short_channel_id: u64,
        htlc_id: u64,
        incoming_packet_shared_secret: [u8; 32],
+       phantom_shared_secret: Option<[u8; 32]>,
 
        // This field is consumed by `claim_funds_from_hop()` when updating a force-closed backwards
        // channel with a preimage provided by the forward channel.
@@ -2072,7 +2074,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
        }
 
        fn construct_recv_pending_htlc_info(&self, hop_data: msgs::OnionHopData, shared_secret: [u8; 32],
-               payment_hash: PaymentHash, amt_msat: u64, cltv_expiry: u32) -> Result<PendingHTLCInfo, ReceiveError>
+               payment_hash: PaymentHash, amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>) -> Result<PendingHTLCInfo, ReceiveError>
        {
                // final_incorrect_cltv_expiry
                if hop_data.outgoing_cltv_value != cltv_expiry {
@@ -2129,6 +2131,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                        PendingHTLCRouting::Receive {
                                                payment_data: data,
                                                incoming_cltv_expiry: hop_data.outgoing_cltv_value,
+                                               phantom_shared_secret,
                                        }
                                } else if let Some(payment_preimage) = keysend_preimage {
                                        // We need to check that the sender knows the keysend preimage before processing this
@@ -2232,7 +2235,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                let pending_forward_info = match next_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) {
+                               match self.construct_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash, msg.amount_msat, msg.cltv_expiry, None) {
                                        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
@@ -3012,17 +3015,18 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                                                routing, incoming_shared_secret, payment_hash, amt_to_forward, outgoing_cltv_value },
                                                                                prev_funding_outpoint } => {
                                                                                        macro_rules! fail_forward {
-                                                                                               ($msg: expr, $err_code: expr, $err_data: expr) => {
+                                                                                               ($msg: expr, $err_code: expr, $err_data: expr, $phantom_ss: expr) => {
                                                                                                        {
                                                                                                                log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
                                                                                                                let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
-                                                                                                                       short_channel_id: short_chan_id,
+                                                                                                                       short_channel_id: prev_short_channel_id,
                                                                                                                        outpoint: prev_funding_outpoint,
                                                                                                                        htlc_id: prev_htlc_id,
                                                                                                                        incoming_packet_shared_secret: incoming_shared_secret,
+                                                                                                                       phantom_shared_secret: $phantom_ss,
                                                                                                                });
                                                                                                                failed_forwards.push((htlc_source, payment_hash,
-                                                                                                                               HTLCFailReason::Reason { failure_code: $err_code, data: $err_data }
+                                                                                                                       HTLCFailReason::Reason { failure_code: $err_code, data: $err_data }
                                                                                                                ));
                                                                                                                continue;
                                                                                                        }
@@ -3031,34 +3035,39 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                                                        if let PendingHTLCRouting::Forward { onion_packet, .. } = routing {
                                                                                                let phantom_secret_res = self.keys_manager.get_node_secret(Recipient::PhantomNode);
                                                                                                if phantom_secret_res.is_ok() && fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, short_chan_id) {
-                                                                                                       let shared_secret = {
+                                                                                                       let phantom_shared_secret = {
                                                                                                                let mut arr = [0; 32];
                                                                                                                arr.copy_from_slice(&SharedSecret::new(&onion_packet.public_key.unwrap(), &phantom_secret_res.unwrap())[..]);
                                                                                                                arr
                                                                                                        };
-                                                                                                       let next_hop = match onion_utils::decode_next_hop(shared_secret, &onion_packet.hop_data, onion_packet.hmac, payment_hash) {
+                                                                                                       let next_hop = match onion_utils::decode_next_hop(phantom_shared_secret, &onion_packet.hop_data, onion_packet.hmac, payment_hash) {
                                                                                                                Ok(res) => res,
                                                                                                                Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
-                                                                                                                       fail_forward!(err_msg, err_code, Vec::new());
+                                                                                                                       let sha256_of_onion = Sha256::hash(&onion_packet.hop_data).into_inner();
+                                                                                                                       // In this scenario, the phantom would have sent us an
+                                                                                                                       // `update_fail_malformed_htlc`, meaning here we encrypt the error as
+                                                                                                                       // if it came from us (the second-to-last hop) but contains the sha256
+                                                                                                                       // of the onion.
+                                                                                                                       fail_forward!(err_msg, err_code, sha256_of_onion.to_vec(), None);
                                                                                                                },
                                                                                                                Err(onion_utils::OnionDecodeErr::Relay { err_msg, err_code }) => {
-                                                                                                                       fail_forward!(err_msg, err_code, Vec::new());
+                                                                                                                       fail_forward!(err_msg, err_code, Vec::new(), Some(phantom_shared_secret));
                                                                                                                },
                                                                                                        };
                                                                                                        match next_hop {
                                                                                                                onion_utils::Hop::Receive(hop_data) => {
-                                                                                                                       match self.construct_recv_pending_htlc_info(hop_data, shared_secret, payment_hash, amt_to_forward, outgoing_cltv_value) {
+                                                                                                                       match self.construct_recv_pending_htlc_info(hop_data, incoming_shared_secret, payment_hash, amt_to_forward, outgoing_cltv_value, Some(phantom_shared_secret)) {
                                                                                                                                Ok(info) => phantom_receives.push((prev_short_channel_id, prev_funding_outpoint, vec![(info, prev_htlc_id)])),
-                                                                                                                               Err(ReceiveError { err_code, err_data, msg }) => fail_forward!(msg, err_code, err_data)
+                                                                                                                               Err(ReceiveError { err_code, err_data, msg }) => fail_forward!(msg, err_code, err_data, Some(phantom_shared_secret))
                                                                                                                        }
                                                                                                                },
                                                                                                                _ => panic!(),
                                                                                                        }
                                                                                                } else {
-                                                                                                       fail_forward!(format!("Unknown short channel id {} for forward HTLC", short_chan_id), 0x4000 | 10, Vec::new());
+                                                                                                       fail_forward!(format!("Unknown short channel id {} for forward HTLC", short_chan_id), 0x4000 | 10, Vec::new(), None);
                                                                                                }
                                                                                        } else {
-                                                                                               fail_forward!(format!("Unknown short channel id {} for forward HTLC", short_chan_id), 0x4000 | 10, Vec::new());
+                                                                                               fail_forward!(format!("Unknown short channel id {} for forward HTLC", short_chan_id), 0x4000 | 10, Vec::new(), None);
                                                                                        }
                                                                                },
                                                                        HTLCForwardInfo::FailHTLC { .. } => {
@@ -3066,9 +3075,6 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                                                // the channel is now on chain and our counterparty is
                                                                                // trying to broadcast the HTLC-Timeout, but that's their
                                                                                // problem, not ours.
-                                                                               //
-                                                                               // `fail_htlc_backwards_internal` is never called for
-                                                                               // phantom payments, so this is unreachable for them.
                                                                        }
                                                                }
                                                        }
@@ -3091,6 +3097,8 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                                                outpoint: prev_funding_outpoint,
                                                                                htlc_id: prev_htlc_id,
                                                                                incoming_packet_shared_secret: incoming_shared_secret,
+                                                                               // Phantom payments are only PendingHTLCRouting::Receive.
+                                                                               phantom_shared_secret: None,
                                                                        });
                                                                        match chan.get_mut().send_htlc(amt_to_forward, payment_hash, outgoing_cltv_value, htlc_source.clone(), onion_packet, &self.logger) {
                                                                                Err(e) => {
@@ -3207,11 +3215,11 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                        HTLCForwardInfo::AddHTLC { prev_short_channel_id, prev_htlc_id, forward_info: PendingHTLCInfo {
                                                                        routing, incoming_shared_secret, payment_hash, amt_to_forward, .. },
                                                                        prev_funding_outpoint } => {
-                                                               let (cltv_expiry, onion_payload) = match routing {
-                                                                       PendingHTLCRouting::Receive { payment_data, incoming_cltv_expiry } =>
-                                                                               (incoming_cltv_expiry, OnionPayload::Invoice(payment_data)),
+                                                               let (cltv_expiry, onion_payload, phantom_shared_secret) = match routing {
+                                                                       PendingHTLCRouting::Receive { payment_data, incoming_cltv_expiry, phantom_shared_secret } =>
+                                                                               (incoming_cltv_expiry, OnionPayload::Invoice(payment_data), phantom_shared_secret),
                                                                        PendingHTLCRouting::ReceiveKeysend { payment_preimage, incoming_cltv_expiry } =>
-                                                                               (incoming_cltv_expiry, OnionPayload::Spontaneous(payment_preimage)),
+                                                                               (incoming_cltv_expiry, OnionPayload::Spontaneous(payment_preimage), None),
                                                                        _ => {
                                                                                panic!("short_channel_id == 0 should imply any pending_forward entries are of type Receive");
                                                                        }
@@ -3222,6 +3230,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                                                outpoint: prev_funding_outpoint,
                                                                                htlc_id: prev_htlc_id,
                                                                                incoming_packet_shared_secret: incoming_shared_secret,
+                                                                               phantom_shared_secret,
                                                                        },
                                                                        value: amt_to_forward,
                                                                        cltv_expiry,
@@ -3239,6 +3248,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                                                                outpoint: prev_funding_outpoint,
                                                                                                htlc_id: $htlc.prev_hop.htlc_id,
                                                                                                incoming_packet_shared_secret: $htlc.prev_hop.incoming_packet_shared_secret,
+                                                                                               phantom_shared_secret,
                                                                                        }), payment_hash,
                                                                                        HTLCFailReason::Reason { failure_code: 0x4000 | 15, data: htlc_msat_height_data }
                                                                                ));
@@ -3778,12 +3788,18 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                pending_events.push(path_failure);
                                if let Some(ev) = full_failure_ev { pending_events.push(ev); }
                        },
-                       HTLCSource::PreviousHopData(HTLCPreviousHopData { short_channel_id, htlc_id, incoming_packet_shared_secret, .. }) => {
+                       HTLCSource::PreviousHopData(HTLCPreviousHopData { short_channel_id, htlc_id, incoming_packet_shared_secret, phantom_shared_secret, .. }) => {
                                let err_packet = match onion_error {
                                        HTLCFailReason::Reason { failure_code, data } => {
                                                log_trace!(self.logger, "Failing HTLC with payment_hash {} backwards from us with code {}", log_bytes!(payment_hash.0), failure_code);
-                                               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)
+                                               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 } => {
                                                log_trace!(self.logger, "Failing HTLC with payment_hash {} backwards with pre-built LightningError", log_bytes!(payment_hash.0));
@@ -4487,7 +4503,9 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                                        onion_utils::build_first_hop_failure_packet(incoming_shared_secret, error_code, &{
                                                                                let mut res = Vec::with_capacity(8 + 128);
                                                                                // TODO: underspecified, follow https://github.com/lightningnetwork/lightning-rfc/issues/791
-                                                                               res.extend_from_slice(&byte_utils::be16_to_array(0));
+                                                                               if error_code == 0x1000 | 20 {
+                                                                                       res.extend_from_slice(&byte_utils::be16_to_array(0));
+                                                                               }
                                                                                res.extend_from_slice(&upd.encode_with_len()[..]);
                                                                                res
                                                                        }[..])
@@ -5978,6 +5996,7 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
        },
        (1, Receive) => {
                (0, payment_data, required),
+               (1, phantom_shared_secret, option),
                (2, incoming_cltv_expiry, required),
        },
        (2, ReceiveKeysend) => {
@@ -6069,6 +6088,7 @@ impl_writeable_tlv_based_enum!(PendingHTLCStatus, ;
 
 impl_writeable_tlv_based!(HTLCPreviousHopData, {
        (0, short_channel_id, required),
+       (1, phantom_shared_secret, option),
        (2, outpoint, required),
        (4, htlc_id, required),
        (6, incoming_packet_shared_secret, required)