Merge pull request #2514 from valentinewallace/2023-08-compute-blindedpayinfo

Aggregate `BlindedPayInfo` for blinded routes

Author: TheBlueMatt

lightning/src/blinded_path/mod.rs

@@ -15,8 +15,9 @@ pub(crate) mod utils;
 
 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
 
-use crate::sign::EntropySource;
 use crate::ln::msgs::DecodeError;
+use crate::offers::invoice::BlindedPayInfo;
+use crate::sign::EntropySource;
 use crate::util::ser::{Readable, Writeable, Writer};
 
 use crate::io;
@@ -75,25 +76,31 @@ impl BlindedPath {
 		})
 	}
 
-	/// Create a blinded path for a payment, to be forwarded along `path`. The last node
-	/// in `path` will be the destination node.
+	/// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`.
+	///
+	/// Errors if:
+	/// * a provided node id is invalid
+	/// * [`BlindedPayInfo`] calculation results in an integer overflow
+	/// * any unknown features are required in the provided [`ForwardTlvs`]
 	///
-	/// Errors if `path` is empty or a node id in `path` is invalid.
+	/// [`ForwardTlvs`]: crate::blinded_path::payment::ForwardTlvs
 	//  TODO: make all payloads the same size with padding + add dummy hops
 	pub fn new_for_payment<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>(
-		intermediate_nodes: &[(PublicKey, payment::ForwardTlvs)], payee_node_id: PublicKey,
-		payee_tlvs: payment::ReceiveTlvs, entropy_source: &ES, secp_ctx: &Secp256k1<T>
-	) -> Result<Self, ()> {
+		intermediate_nodes: &[payment::ForwardNode], payee_node_id: PublicKey,
+		payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, entropy_source: &ES,
+		secp_ctx: &Secp256k1<T>
+	) -> Result<(BlindedPayInfo, Self), ()> {
 		let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 		let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 
-		Ok(BlindedPath {
-			introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.0),
+		let blinded_payinfo = payment::compute_payinfo(intermediate_nodes, &payee_tlvs, htlc_maximum_msat)?;
+		Ok((blinded_payinfo, BlindedPath {
+			introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.node_id),
 			blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
 			blinded_hops: payment::blinded_hops(
 				secp_ctx, intermediate_nodes, payee_node_id, payee_tlvs, &blinding_secret
 			).map_err(|_| ())?,
-		})
+		}))
 	}
 }