Test recipient failing an HTLC received to a multi-hop blinded path
[rust-lightning] / lightning / src / ln / onion_payment.rs
index ca15a37c072d89625a0a235fb226d170f758cdb4..5ea07cfab30db4325bc71415f1b3f331ca1a37dc 100644 (file)
@@ -1,10 +1,12 @@
-//! Utilities for channelmanager.rs
+//! Utilities to decode payment onions and do contextless validation of incoming payments.
 //!
-//! Includes a public [`peel_payment_onion`] function for use by external projects or libraries.
+//! Primarily features [`peel_payment_onion`], which allows the decoding of an onion statelessly
+//! and can be used to predict whether we'd accept a payment.
 
-use bitcoin::hashes::Hash;
+use bitcoin::hashes::{Hash, HashEngine};
+use bitcoin::hashes::hmac::{Hmac, HmacEngine};
 use bitcoin::hashes::sha256::Hash as Sha256;
-use bitcoin::secp256k1::{self, Secp256k1, PublicKey};
+use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1};
 
 use crate::blinded_path;
 use crate::blinded_path::payment::{PaymentConstraints, PaymentRelay};
@@ -110,16 +112,21 @@ pub(super) fn create_recv_pending_htlc_info(
        amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>, allow_underpay: bool,
        counterparty_skimmed_fee_msat: Option<u64>, current_height: u32, accept_mpp_keysend: bool,
 ) -> Result<PendingHTLCInfo, InboundOnionErr> {
-       let (payment_data, keysend_preimage, custom_tlvs, onion_amt_msat, outgoing_cltv_value, payment_metadata) = match hop_data {
+       let (
+               payment_data, keysend_preimage, custom_tlvs, onion_amt_msat, outgoing_cltv_value,
+               payment_metadata, requires_blinded_error
+       ) = match hop_data {
                msgs::InboundOnionPayload::Receive {
                        payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata, ..
                } =>
-                       (payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata),
+                       (payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata,
+                        false),
                msgs::InboundOnionPayload::BlindedReceive {
-                       amt_msat, total_msat, outgoing_cltv_value, payment_secret, ..
+                       amt_msat, total_msat, outgoing_cltv_value, payment_secret, intro_node_blinding_point, ..
                } => {
                        let payment_data = msgs::FinalOnionHopData { payment_secret, total_msat };
-                       (Some(payment_data), None, Vec::new(), amt_msat, outgoing_cltv_value, None)
+                       (Some(payment_data), None, Vec::new(), amt_msat, outgoing_cltv_value, None,
+                        intro_node_blinding_point.is_none())
                }
                msgs::InboundOnionPayload::Forward { .. } => {
                        return Err(InboundOnionErr {
@@ -206,6 +213,7 @@ pub(super) fn create_recv_pending_htlc_info(
                        incoming_cltv_expiry: outgoing_cltv_value,
                        phantom_shared_secret,
                        custom_tlvs,
+                       requires_blinded_error,
                }
        } else {
                return Err(InboundOnionErr {
@@ -225,7 +233,9 @@ pub(super) fn create_recv_pending_htlc_info(
        })
 }
 
-/// Peel one layer off an incoming onion, returning [`PendingHTLCInfo`] (either Forward or Receive).
+/// Peel one layer off an incoming onion, returning a [`PendingHTLCInfo`] that contains information
+/// about the intended next-hop for the HTLC.
+///
 /// This does all the relevant context-free checks that LDK requires for payment relay or
 /// acceptance. If the payment is to be received, and the amount matches the expected amount for
 /// a given invoice, this indicates the [`msgs::UpdateAddHTLC`], once fully committed in the
@@ -234,7 +244,7 @@ pub(super) fn create_recv_pending_htlc_info(
 /// [`Event::PaymentClaimable`]: crate::events::Event::PaymentClaimable
 pub fn peel_payment_onion<NS: Deref, L: Deref, T: secp256k1::Verification>(
        msg: &msgs::UpdateAddHTLC, node_signer: &NS, logger: &L, secp_ctx: &Secp256k1<T>,
-       cur_height: u32, accept_mpp_keysend: bool,
+       cur_height: u32, accept_mpp_keysend: bool, allow_skimmed_fees: bool,
 ) -> Result<PendingHTLCInfo, InboundOnionErr>
 where
        NS::Target: NodeSigner,
@@ -273,6 +283,10 @@ where
                                        err_data: Vec::new(),
                                });
                        }
+
+                       // TODO: If this is potentially a phantom payment we should decode the phantom payment
+                       // onion here and check it.
+
                        create_fwd_pending_htlc_info(
                                msg, next_hop_data, next_hop_hmac, new_packet_bytes, shared_secret,
                                Some(next_packet_pubkey)
@@ -281,7 +295,7 @@ where
                onion_utils::Hop::Receive(received_data) => {
                        create_recv_pending_htlc_info(
                                received_data, shared_secret, msg.payment_hash, msg.amount_msat, msg.cltv_expiry,
-                               None, false, msg.skimmed_fee_msat, cur_height, accept_mpp_keysend,
+                               None, allow_skimmed_fees, msg.skimmed_fee_msat, cur_height, accept_mpp_keysend,
                        )?
                }
        })
@@ -319,8 +333,14 @@ where
                return_malformed_err!("invalid ephemeral pubkey", 0x8000 | 0x4000 | 6);
        }
 
+       let blinded_node_id_tweak = msg.blinding_point.map(|bp| {
+               let blinded_tlvs_ss = node_signer.ecdh(Recipient::Node, &bp, None).unwrap().secret_bytes();
+               let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
+               hmac.input(blinded_tlvs_ss.as_ref());
+               Scalar::from_be_bytes(Hmac::from_engine(hmac).to_byte_array()).unwrap()
+       });
        let shared_secret = node_signer.ecdh(
-               Recipient::Node, &msg.onion_routing_packet.public_key.unwrap(), None
+               Recipient::Node, &msg.onion_routing_packet.public_key.unwrap(), blinded_node_id_tweak.as_ref()
        ).unwrap().secret_bytes();
 
        if msg.onion_routing_packet.version != 0 {
@@ -348,7 +368,7 @@ where
 
        let next_hop = match onion_utils::decode_next_payment_hop(
                shared_secret, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
-               msg.payment_hash, node_signer
+               msg.payment_hash, msg.blinding_point, node_signer
        ) {
                Ok(res) => res,
                Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
@@ -477,7 +497,7 @@ mod tests {
                let msg = make_update_add_msg(amount_msat, cltv_expiry, payment_hash, onion);
                let logger = test_utils::TestLogger::with_id("bob".to_string());
 
-               let peeled = peel_payment_onion(&msg, &&bob, &&logger, &secp_ctx, cur_height, true)
+               let peeled = peel_payment_onion(&msg, &&bob, &&logger, &secp_ctx, cur_height, true, false)
                        .map_err(|e| e.msg).unwrap();
 
                let next_onion = match peeled.routing {
@@ -488,7 +508,7 @@ mod tests {
                };
 
                let msg2 = make_update_add_msg(amount_msat, cltv_expiry, payment_hash, next_onion);
-               let peeled2 = peel_payment_onion(&msg2, &&charlie, &&logger, &secp_ctx, cur_height, true)
+               let peeled2 = peel_payment_onion(&msg2, &&charlie, &&logger, &secp_ctx, cur_height, true, false)
                        .map_err(|e| e.msg).unwrap();
 
                match peeled2.routing {