Fix phantom malformed onion error packet

Ensure we fail back phantom malformed payments with an update_fail_htlc s.t.
the error contains the sha256 of the onion, per LN protocol.

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index a6856b4119853e67435ab7f20d0bca4d261e8638..373b0a199303e09db82ca275f3dbbca914c1515e 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -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
@@ -376,8 +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,
@@ -3043,7 +3043,12 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                                                                        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(), None);
+                                                                                                                       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(), Some(phantom_shared_secret));

diff --git a/lightning/src/ln/onion_route_tests.rs b/lightning/src/ln/onion_route_tests.rs
index 4feae104d759a11fb47ee0b21b1f8f4be20b2311..4936941ea2d7d1230236d04ca3eda3d58fb165d0 100644 (file)
--- a/lightning/src/ln/onion_route_tests.rs
+++ b/lightning/src/ln/onion_route_tests.rs
@@ -12,25 +12,28 @@
 //! returned errors decode to the correct thing.
 
 use chain::channelmonitor::{CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS};
+use chain::keysinterface::{KeysInterface, Recipient};
 use ln::{PaymentHash, PaymentSecret};
-use ln::channelmanager::{HTLCForwardInfo, CLTV_FAR_FAR_AWAY};
+use ln::channelmanager::{HTLCForwardInfo, CLTV_FAR_FAR_AWAY, MIN_CLTV_EXPIRY_DELTA, PendingHTLCInfo, PendingHTLCRouting};
 use ln::onion_utils;
-use routing::network_graph::NetworkUpdate;
-use routing::router::Route;
-use ln::features::InitFeatures;
+use routing::network_graph::{NetworkUpdate, RoutingFees};
+use routing::router::{get_route, PaymentParameters, Route, RouteHint, RouteHintHop};
+use ln::features::{InitFeatures, InvoiceFeatures};
 use ln::msgs;
 use ln::msgs::{ChannelMessageHandler, ChannelUpdate, OptionalField};
 use util::events::{Event, MessageSendEvent, MessageSendEventsProvider};
 use util::ser::{Writeable, Writer};
+use util::test_utils;
 use util::config::UserConfig;
 
 use bitcoin::hash_types::BlockHash;
 
 use bitcoin::hashes::Hash;
+use bitcoin::hashes::sha256::Hash as Sha256;
 
 use bitcoin::secp256k1;
 use bitcoin::secp256k1::Secp256k1;
-use bitcoin::secp256k1::key::SecretKey;
+use bitcoin::secp256k1::key::{PublicKey, SecretKey};
 
 use io;
 use prelude::*;
@@ -573,3 +576,104 @@ fn test_onion_failure() {
                nodes[2].node.fail_htlc_backwards(&payment_hash);
        }, true, Some(23), None, None);
 }
+
+macro_rules! get_phantom_route {
+       ($nodes: expr, $amt: expr, $channel: expr) => {{
+               let secp_ctx = Secp256k1::new();
+               let phantom_secret = $nodes[1].keys_manager.get_node_secret(Recipient::PhantomNode).unwrap();
+               let phantom_pubkey = PublicKey::from_secret_key(&secp_ctx, &phantom_secret);
+               let phantom_route_hint = $nodes[1].node.get_phantom_route_hints();
+               let payment_params = PaymentParameters::from_node_id(phantom_pubkey)
+                       .with_features(InvoiceFeatures::known())
+                       .with_route_hints(vec![RouteHint(vec![
+                                       RouteHintHop {
+                                               src_node_id: $nodes[0].node.get_our_node_id(),
+                                               short_channel_id: $channel.0.contents.short_channel_id,
+                                               fees: RoutingFees {
+                                                       base_msat: $channel.0.contents.fee_base_msat,
+                                                       proportional_millionths: $channel.0.contents.fee_proportional_millionths,
+                                               },
+                                               cltv_expiry_delta: $channel.0.contents.cltv_expiry_delta,
+                                               htlc_minimum_msat: None,
+                                               htlc_maximum_msat: None,
+                                       },
+                                       RouteHintHop {
+                                               src_node_id: phantom_route_hint.real_node_pubkey,
+                                               short_channel_id: phantom_route_hint.phantom_scid,
+                                               fees: RoutingFees {
+                                                       base_msat: 0,
+                                                       proportional_millionths: 0,
+                                               },
+                                               cltv_expiry_delta: MIN_CLTV_EXPIRY_DELTA,
+                                               htlc_minimum_msat: None,
+                                               htlc_maximum_msat: None,
+                                       }
+               ])]);
+               let scorer = test_utils::TestScorer::with_penalty(0);
+               (get_route(
+                       &$nodes[0].node.get_our_node_id(), &payment_params, $nodes[0].network_graph,
+                       Some(&$nodes[0].node.list_usable_channels().iter().collect::<Vec<_>>()),
+                       $amt, TEST_FINAL_CLTV, $nodes[0].logger, &scorer
+               ).unwrap(), phantom_route_hint.phantom_scid)
+       }
+}}
+
+#[test]
+fn test_phantom_onion_hmac_failure() {
+       let chanmon_cfgs = create_chanmon_cfgs(2);
+       let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+       let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+       let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+       let channel = create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known());
+
+       // Get the route.
+       let recv_value_msat = 10_000;
+       let (_, payment_hash, payment_secret) = get_payment_preimage_hash!(nodes[1], Some(recv_value_msat));
+       let (route, phantom_scid) = get_phantom_route!(nodes, recv_value_msat, channel);
+
+       // Route the HTLC through to the destination.
+       nodes[0].node.send_payment(&route, payment_hash.clone(), &Some(payment_secret)).unwrap();
+       check_added_monitors!(nodes[0], 1);
+       let update_0 = get_htlc_update_msgs!(nodes[0], nodes[1].node.get_our_node_id());
+       let mut update_add = update_0.update_add_htlcs[0].clone();
+
+       nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &update_add);
+       commitment_signed_dance!(nodes[1], nodes[0], &update_0.commitment_signed, false, true);
+
+       // Modify the payload so the phantom hop's HMAC is bogus.
+       let sha256_of_onion = {
+               let mut channel_state = nodes[1].node.channel_state.lock().unwrap();
+               let mut pending_forward = channel_state.forward_htlcs.get_mut(&phantom_scid).unwrap();
+               match pending_forward[0] {
+                       HTLCForwardInfo::AddHTLC {
+                               forward_info: PendingHTLCInfo {
+                                       routing: PendingHTLCRouting::Forward { ref mut onion_packet, .. },
+                                       ..
+                               }, ..
+                       } => {
+                               onion_packet.hmac[onion_packet.hmac.len() - 1] ^= 1;
+                               Sha256::hash(&onion_packet.hop_data).into_inner().to_vec()
+                       },
+                       _ => panic!("Unexpected forward"),
+               }
+       };
+       expect_pending_htlcs_forwardable_ignore!(nodes[1]);
+       nodes[1].node.process_pending_htlc_forwards();
+       expect_pending_htlcs_forwardable_ignore!(nodes[1]);
+       nodes[1].node.process_pending_htlc_forwards();
+       let update_1 = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+       check_added_monitors!(&nodes[1], 1);
+       assert!(update_1.update_fail_htlcs.len() == 1);
+       let fail_msg = update_1.update_fail_htlcs[0].clone();
+       nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &fail_msg);
+       commitment_signed_dance!(nodes[0], nodes[1], update_1.commitment_signed, false);
+
+       // Ensure the payment fails with the expected error.
+       let mut fail_conditions = PaymentFailedConditions::new()
+               .blamed_scid(phantom_scid)
+               .blamed_chan_closed(true)
+               .expected_htlc_error_data(0x8000 | 0x4000 | 5, &sha256_of_onion);
+       expect_payment_failed_conditions!(nodes[0], payment_hash, false, fail_conditions);
+}
+