Fix unused (import) warnings in `no-std` builds
[rust-lightning] / lightning / src / ln / onion_payment.rs
index 06a9ae07e1e0024c075082711d9064278227cf5a..5966dce91039db227155264deb0557a2ed2012ff 100644 (file)
@@ -3,9 +3,10 @@
 //! 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};
@@ -23,6 +24,7 @@ use crate::prelude::*;
 use core::ops::Deref;
 
 /// Invalid inbound onion payment.
+#[derive(Debug)]
 pub struct InboundOnionErr {
        /// BOLT 4 error code.
        pub err_code: u16,
@@ -32,6 +34,15 @@ pub struct InboundOnionErr {
        pub msg: &'static str,
 }
 
+fn check_blinded_payment_constraints(
+       amt_msat: u64, cltv_expiry: u32, constraints: &PaymentConstraints
+) -> Result<(), ()> {
+       if amt_msat < constraints.htlc_minimum_msat ||
+               cltv_expiry > constraints.max_cltv_expiry
+       { return Err(()) }
+       Ok(())
+}
+
 fn check_blinded_forward(
        inbound_amt_msat: u64, inbound_cltv_expiry: u32, payment_relay: &PaymentRelay,
        payment_constraints: &PaymentConstraints, features: &BlindedHopFeatures
@@ -42,9 +53,8 @@ fn check_blinded_forward(
        let outgoing_cltv_value = inbound_cltv_expiry.checked_sub(
                payment_relay.cltv_expiry_delta as u32
        ).ok_or(())?;
-       if inbound_amt_msat < payment_constraints.htlc_minimum_msat ||
-               outgoing_cltv_value > payment_constraints.max_cltv_expiry
-               { return Err(()) }
+       check_blinded_payment_constraints(inbound_amt_msat, outgoing_cltv_value, payment_constraints)?;
+
        if features.requires_unknown_bits_from(&BlindedHopFeatures::empty()) { return Err(()) }
        Ok((amt_to_forward, outgoing_cltv_value))
 }
@@ -111,16 +121,30 @@ 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,
+                       payment_constraints, ..
                } => {
+                       check_blinded_payment_constraints(amt_msat, cltv_expiry, &payment_constraints)
+                               .map_err(|()| {
+                                       InboundOnionErr {
+                                               err_code: INVALID_ONION_BLINDING,
+                                               err_data: vec![0; 32],
+                                               msg: "Amount or cltv_expiry violated blinded payment constraints",
+                                       }
+                               })?;
                        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 {
@@ -207,6 +231,7 @@ 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 {
@@ -312,11 +337,16 @@ where
                ($msg: expr, $err_code: expr) => {
                        {
                                log_info!(logger, "Failed to accept/forward incoming HTLC: {}", $msg);
+                               let (sha256_of_onion, failure_code) = if msg.blinding_point.is_some() {
+                                       ([0; 32], INVALID_ONION_BLINDING)
+                               } else {
+                                       (Sha256::hash(&msg.onion_routing_packet.hop_data).to_byte_array(), $err_code)
+                               };
                                return Err(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
                                        channel_id: msg.channel_id,
                                        htlc_id: msg.htlc_id,
-                                       sha256_of_onion: Sha256::hash(&msg.onion_routing_packet.hop_data).to_byte_array(),
-                                       failure_code: $err_code,
+                                       sha256_of_onion,
+                                       failure_code,
                                }));
                        }
                }
@@ -326,8 +356,14 @@ 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 {
@@ -342,6 +378,10 @@ where
        macro_rules! return_err {
                ($msg: expr, $err_code: expr, $data: expr) => {
                        {
+                               if msg.blinding_point.is_some() {
+                                       return_malformed_err!($msg, INVALID_ONION_BLINDING)
+                               }
+
                                log_info!(logger, "Failed to accept/forward incoming HTLC: {}", $msg);
                                return Err(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
                                        channel_id: msg.channel_id,
@@ -355,7 +395,7 @@ 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 }) => {
@@ -448,7 +488,7 @@ pub(super) fn check_incoming_htlc_cltv(
 mod tests {
        use bitcoin::hashes::Hash;
        use bitcoin::hashes::sha256::Hash as Sha256;
-       use bitcoin::secp256k1::{PublicKey, SecretKey};
+       use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
        use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
        use crate::ln::ChannelId;
        use crate::ln::channelmanager::RecipientOnionFields;
@@ -458,6 +498,38 @@ mod tests {
        use crate::routing::router::{Path, RouteHop};
        use crate::util::test_utils;
 
+       #[test]
+       fn fail_construct_onion_on_too_big_payloads() {
+               // Ensure that if we call `construct_onion_packet` and friends where payloads are too large for
+               // the allotted packet length, we'll fail to construct. Previously, senders would happily
+               // construct invalid packets by array-shifting the final node's HMAC out of the packet when
+               // adding an intermediate onion layer, causing the receiver to error with "final payload
+               // provided for us as an intermediate node."
+               let secp_ctx = Secp256k1::new();
+               let bob = crate::sign::KeysManager::new(&[2; 32], 42, 42);
+               let bob_pk = PublicKey::from_secret_key(&secp_ctx, &bob.get_node_secret_key());
+               let charlie = crate::sign::KeysManager::new(&[3; 32], 42, 42);
+               let charlie_pk = PublicKey::from_secret_key(&secp_ctx, &charlie.get_node_secret_key());
+
+               let (
+                       session_priv, total_amt_msat, cur_height, mut recipient_onion, keysend_preimage, payment_hash,
+                       prng_seed, hops, ..
+               ) = payment_onion_args(bob_pk, charlie_pk);
+
+               // Ensure the onion will not fit all the payloads by adding a large custom TLV.
+               recipient_onion.custom_tlvs.push((13377331, vec![0; 1156]));
+
+               let path = Path { hops, blinded_tail: None, };
+               let onion_keys = super::onion_utils::construct_onion_keys(&secp_ctx, &path, &session_priv).unwrap();
+               let (onion_payloads, ..) = super::onion_utils::build_onion_payloads(
+                       &path, total_amt_msat, recipient_onion, cur_height + 1, &Some(keysend_preimage)
+               ).unwrap();
+
+               assert!(super::onion_utils::construct_onion_packet(
+                               onion_payloads, onion_keys, prng_seed, &payment_hash
+               ).is_err());
+       }
+
        #[test]
        fn test_peel_payment_onion() {
                use super::*;