X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Fonion_payment.rs;h=7c0d32a52a53bccab19177fa014b90e477cd317c;hb=a4f2c36015545c9607eb07a4bef5061997d2d322;hp=ca15a37c072d89625a0a235fb226d170f758cdb4;hpb=37150b4d697f723f278b6cf3f63892df272b9aa5;p=rust-lightning

diff --git a/lightning/src/ln/onion_payment.rs b/lightning/src/ln/onion_payment.rs
index ca15a37c..7c0d32a5 100644
--- a/lightning/src/ln/onion_payment.rs
+++ b/lightning/src/ln/onion_payment.rs
@@ -1,6 +1,7 @@
-//! 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::sha256::Hash as Sha256;
@@ -22,6 +23,7 @@ use crate::prelude::*;
 use core::ops::Deref;
 
 /// Invalid inbound onion payment.
+#[derive(Debug)]
 pub struct InboundOnionErr {
 	/// BOLT 4 error code.
 	pub err_code: u16,
@@ -225,7 +227,9 @@ 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 +238,7 @@ 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 +277,10 @@ 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 +289,7 @@ 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,
 			)?
 		}
 	})
@@ -441,7 +449,7 @@ 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;
@@ -451,6 +459,38 @@ 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::*;
@@ -477,7 +517,7 @@ 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 +528,7 @@ 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 {