Remove Readable for BlindedPathPadding

Padding serves as filler data with no explicit use case, making it
more efficient to ignore it rather than read and discard it.
This change simplifies the code by removing unnecessary `Readable`
implementation for padding.

Author: shaavan

lightning/src/blinded_path/payment.rs

@@ -506,7 +506,10 @@ impl<'a> Writeable for BlindedPaymentTlvsRef<'a> {
 impl Readable for BlindedPaymentTlvs {
 	fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 		_init_and_read_tlv_stream!(r, {
-			(1, _padding, option),
+			// Reasoning: Padding refers to filler data added to a packet to increase
+			// its size and obscure its actual length. Since padding contains no meaningful
+			// information, we can safely omit reading it here.
+			// (1, _padding, option),
 			(2, scid, option),
 			(8, next_blinding_override, option),
 			(10, payment_relay, option),
@@ -516,7 +519,6 @@ impl Readable for BlindedPaymentTlvs {
 			(65537, payment_context, option),
 			(65539, authentication, option),
 		});
-		let _padding: Option<utils::BlindedPathPadding> = _padding;
 
 		if let Some(short_channel_id) = scid {
 			if payment_secret.is_some() {

lightning/src/blinded_path/utils.rs

@@ -18,12 +18,9 @@ use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey};
 use super::message::BlindedMessagePath;
 use super::{BlindedHop, BlindedPath};
 use crate::crypto::streams::ChaChaPolyWriteAdapter;
-use crate::ln::msgs::DecodeError;
 use crate::ln::onion_utils;
 use crate::onion_message::messenger::Destination;
-use crate::util::ser::{Readable, Writeable};
-
-use crate::io;
+use crate::util::ser::Writeable;
 
 use core::borrow::Borrow;
 
@@ -201,15 +198,3 @@ fn encrypt_payload<P: Writeable>(payload: P, encrypted_tlvs_rho: [u8; 32]) -> Ve
 ///
 /// 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 {
-			let mut buf = [0; 8192];
-			if reader.read(&mut buf[..])? == 0 {
-				break;
-			}
-		}
-		Ok(Self {})
-	}
-}

lightning/src/onion_message/packet.rs

@@ -13,7 +13,6 @@ use bitcoin::secp256k1::PublicKey;
 use bitcoin::secp256k1::ecdh::SharedSecret;
 
 use crate::blinded_path::message::{BlindedMessagePath, ForwardTlvs, NextMessageHop, ReceiveTlvs};
-use crate::blinded_path::utils::BlindedPathPadding;
 use crate::ln::msgs::DecodeError;
 use crate::ln::onion_utils;
 #[cfg(async_payments)]
@@ -342,13 +341,15 @@ pub(crate) enum ControlTlvs {
 impl Readable for ControlTlvs {
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 		_init_and_read_tlv_stream!(r, {
-			(1, _padding, option),
+			// Reasoning: Padding refers to filler data added to a packet to increase
+			// its size and obscure its actual length. Since padding contains no meaningful
+			// information, we can safely omit reading it here.
+			// (1, _padding, option),
 			(2, short_channel_id, option),
 			(4, next_node_id, option),
 			(8, next_blinding_override, option),
 			(65537, context, option),
 		});
-		let _padding: Option<BlindedPathPadding> = _padding;
 
 		let next_hop = match (short_channel_id, next_node_id) {
 			(Some(_), Some(_)) => return Err(DecodeError::InvalidValue),