Add parsing logic for dummy hops

Adds support for identifying and handling dummy hops during
the onion message peeling process.
Ensures that Dummy Forward TLVs are correctly recognized and
interpreted as non-routing hops.

Co-authored-by: valentinewallace <[email protected]>

Author: shaavan

lightning/src/onion_message/messenger.rs

@@ -1104,11 +1104,6 @@ where
 			})),
 			Some((next_hop_hmac, new_packet_bytes)),
 		)) => {
-			// TODO: we need to check whether `next_hop` is our node, in which case this is a dummy
-			// blinded hop and this onion message is destined for us. In this situation, we should keep
-			// unwrapping the onion layers to get to the final payload. Since we don't have the option
-			// of creating blinded paths with dummy hops currently, we should be ok to not handle this
-			// for now.
 			let packet_pubkey = msg.onion_routing_packet.public_key;
 			let new_pubkey_opt =
 				onion_utils::next_hop_pubkey(&secp_ctx, packet_pubkey, &onion_decode_ss);
@@ -1145,7 +1140,18 @@ where
 				onion_routing_packet: outgoing_packet,
 			};
 
-			Ok(PeeledOnion::Forward(next_hop, onion_message))
+			let our_node_id = node_signer.get_node_id(Recipient::Node).unwrap();
+
+			match next_hop {
+				NextMessageHop::NodeId(ref id) if id == &our_node_id => peel_onion_message(
+					&onion_message,
+					secp_ctx,
+					node_signer,
+					logger,
+					custom_handler,
+				),
+				_ => Ok(PeeledOnion::Forward(next_hop, onion_message)),
+			}
 		},
 		Err(e) => {
 			log_trace!(logger, "Errored decoding onion message packet: {:?}", e);