Rename Padding -> BlindedPathPadding

Renaming the struct to `BlindedPathPadding` makes its purpose explicit,
clarifying that it is specifically used for `Blinded{Message/Payment}Paths`.

Author: shaavan

lightning/src/blinded_path/payment.rs

@@ -530,7 +530,7 @@ impl Readable for BlindedPaymentTlvs {
 			(65537, payment_context, option),
 			(65539, authentication, option),
 		});
-		let _padding: Option<utils::Padding> = _padding;
+		let _padding: Option<utils::BlindedPathPadding> = _padding;
 
 		if let Some(short_channel_id) = scid {
 			if payment_secret.is_some() {

lightning/src/blinded_path/utils.rs

@@ -196,11 +196,12 @@ fn encrypt_payload<P: Writeable>(payload: P, encrypted_tlvs_rho: [u8; 32]) -> Ve
 	write_adapter.encode()
 }
 
-/// Blinded path encrypted payloads may be padded to ensure they are equal length.
+/// A data structure used exclusively to pad blinded path payloads, ensuring they are of
+/// equal length. Padding is written at Type 1 for compatibility with the lightning specification.
 ///
-/// Reads padding to the end, ignoring what's read.
-pub(crate) struct Padding {}
-impl Readable for Padding {
+/// For more details, see the [BOLTs Specification - Encrypted Recipient Data](https://github.com/lightning/bolts/blob/8707471dbc23245fb4d84c5f5babac1197f1583e/04-onion-routing.md#inside-encrypted_recipient_data-encrypted_data_tlv).
+pub(crate) struct BlindedPathPadding {}
+impl Readable for BlindedPathPadding {
 	#[inline]
 	fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 		loop {

lightning/src/onion_message/packet.rs

@@ -18,7 +18,7 @@ use super::dns_resolution::DNSResolverMessage;
 use super::messenger::CustomOnionMessageHandler;
 use super::offers::OffersMessage;
 use crate::blinded_path::message::{BlindedMessagePath, ForwardTlvs, NextMessageHop, ReceiveTlvs};
-use crate::blinded_path::utils::Padding;
+use crate::blinded_path::utils::BlindedPathPadding;
 use crate::crypto::streams::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
 use crate::ln::msgs::DecodeError;
 use crate::ln::onion_utils;
@@ -342,7 +342,7 @@ impl Readable for ControlTlvs {
 			(8, next_blinding_override, option),
 			(65537, context, option),
 		});
-		let _padding: Option<Padding> = _padding;
+		let _padding: Option<BlindedPathPadding> = _padding;
 
 		let next_hop = match (short_channel_id, next_node_id) {
 			(Some(_), Some(_)) => return Err(DecodeError::InvalidValue),