Use PublicKey values in construct_keys_callback

Instead of accepting iterators yielding PublicKey by reference in
utils::construct_keys_callback, take iterators yielding values since
these implement Copy and need to be copied anyway. This will help avoid
a situation when padding where both a reference and mutable reference
are needed.

Author: jkczyz

lightning/src/blinded_path/message.rs

@@ -374,14 +374,14 @@ pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
 	secp_ctx: &Secp256k1<T>, intermediate_nodes: &[ForwardNode], recipient_node_id: PublicKey,
 	context: MessageContext, session_priv: &SecretKey
 ) -> Result<Vec<BlindedHop>, secp256k1::Error> {
-	let pks = intermediate_nodes.iter().map(|node| &node.node_id)
-		.chain(core::iter::once(&recipient_node_id));
+	let pks = intermediate_nodes.iter().map(|node| node.node_id)
+		.chain(core::iter::once(recipient_node_id));
 	let tlvs = pks.clone()
 		.skip(1) // The first node's TLVs contains the next node's pubkey
 		.zip(intermediate_nodes.iter().map(|node| node.short_channel_id))
 		.map(|(pubkey, scid)| match scid {
 			Some(scid) => NextMessageHop::ShortChannelId(scid),
-			None => NextMessageHop::NodeId(*pubkey),
+			None => NextMessageHop::NodeId(pubkey),
 		})
 		.map(|next_hop| ControlTlvs::Forward(ForwardTlvs { next_hop, next_blinding_override: None }))
 		.chain(core::iter::once(ControlTlvs::Receive(ReceiveTlvs{ context: Some(context) })));

lightning/src/blinded_path/payment.rs

@@ -462,8 +462,8 @@ pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
 	secp_ctx: &Secp256k1<T>, intermediate_nodes: &[ForwardNode],
 	payee_node_id: PublicKey, payee_tlvs: ReceiveTlvs, session_priv: &SecretKey
 ) -> Result<Vec<BlindedHop>, secp256k1::Error> {
-	let pks = intermediate_nodes.iter().map(|node| &node.node_id)
-		.chain(core::iter::once(&payee_node_id));
+	let pks = intermediate_nodes.iter().map(|node| node.node_id)
+		.chain(core::iter::once(payee_node_id));
 	let tlvs = intermediate_nodes.iter().map(|node| BlindedPaymentTlvsRef::Forward(&node.tlvs))
 		.chain(core::iter::once(BlindedPaymentTlvsRef::Receive(&payee_tlvs)));
 	utils::construct_blinded_hops(secp_ctx, pks, tlvs, session_priv)

lightning/src/blinded_path/utils.rs

@@ -91,13 +91,13 @@ pub(crate) fn construct_keys_callback<'a, T, I, F>(
 ) -> Result<(), secp256k1::Error>
 where
 	T: secp256k1::Signing + secp256k1::Verification,
-	I: Iterator<Item=&'a PublicKey>,
+	I: Iterator<Item=PublicKey>,
 	F: FnMut(PublicKey, SharedSecret, PublicKey, [u8; 32], Option<PublicKey>, Option<Vec<u8>>),
 {
 	build_keys_helper!(session_priv, secp_ctx, callback);
 
 	for pk in unblinded_path {
-		build_keys_in_loop!(*pk, false, None);
+		build_keys_in_loop!(pk, false, None);
 	}
 	if let Some(dest) = destination {
 		match dest {
@@ -120,7 +120,7 @@ pub(crate) fn construct_blinded_hops<'a, T, I1, I2>(
 ) -> Result<Vec<BlindedHop>, secp256k1::Error>
 where
 	T: secp256k1::Signing + secp256k1::Verification,
-	I1: Iterator<Item=&'a PublicKey>,
+	I1: Iterator<Item=PublicKey>,
 	I2: Iterator,
 	I2::Item: Writeable
 {

lightning/src/onion_message/messenger.rs

@@ -925,7 +925,7 @@ where
 		}
 	};
 	let (packet_payloads, packet_keys) = packet_payloads_and_keys(
-		&secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret
+		&secp_ctx, intermediate_nodes, destination, contents, reply_path, &blinding_secret
 	)?;
 
 	let prng_seed = entropy_source.get_secure_random_bytes();
@@ -1784,7 +1784,7 @@ pub type SimpleRefOnionMessenger<
 /// Construct onion packet payloads and keys for sending an onion message along the given
 /// `unblinded_path` to the given `destination`.
 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
-	secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
+	secp_ctx: &Secp256k1<S>, unblinded_path: Vec<PublicKey>, destination: Destination, message: T,
 	mut reply_path: Option<BlindedMessagePath>, session_priv: &SecretKey
 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), SendError> {
 	let num_hops = unblinded_path.len() + destination.num_hops();
@@ -1809,7 +1809,8 @@ fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + sec
 	let mut blinded_path_idx = 0;
 	let mut prev_control_tlvs_ss = None;
 	let mut final_control_tlvs = None;
-	utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
+	utils::construct_keys_callback(
+		secp_ctx, unblinded_path.into_iter(), Some(destination), session_priv,
 		|_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 			if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 				if let Some(ss) = prev_control_tlvs_ss.take() {