Move Padding into blinded_path module for use in blinded payments

Author: valentinewallace

lightning/src/blinded_path/utils.rs

@@ -16,11 +16,13 @@ use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey, Scalar};
 use bitcoin::secp256k1::ecdh::SharedSecret;
 
 use super::BlindedPath;
+use crate::ln::msgs::DecodeError;
 use crate::ln::onion_utils;
 use crate::onion_message::Destination;
 use crate::util::chacha20poly1305rfc::ChaChaPolyWriteAdapter;
-use crate::util::ser::{VecWriter, Writeable};
+use crate::util::ser::{Readable, VecWriter, Writeable};
 
+use crate::io;
 use crate::prelude::*;
 
 // TODO: DRY with onion_utils::construct_onion_keys_callback
@@ -107,3 +109,17 @@ pub(super) fn encrypt_payload<P: Writeable>(payload: P, encrypted_tlvs_ss: [u8;
 	writer.0
 }
 
+/// Blinded path encrypted payloads may be padded to ensure they are equal length.
+///
+/// Reads padding to the end, ignoring what's read.
+pub(crate) struct Padding {}
+impl Readable for Padding {
+	#[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

@@ -14,6 +14,7 @@ use bitcoin::secp256k1::ecdh::SharedSecret;
 
 use crate::blinded_path::BlindedPath;
 use crate::blinded_path::message::{ForwardTlvs, ReceiveTlvs};
+use crate::blinded_path::utils::Padding;
 use crate::ln::msgs::DecodeError;
 use crate::ln::onion_utils;
 use super::messenger::CustomOnionMessageHandler;
@@ -306,16 +307,3 @@ impl Readable for ControlTlvs {
 		Ok(payload_fmt)
 	}
 }
-
-/// Reads padding to the end, ignoring what's read.
-pub(crate) struct Padding {}
-impl Readable for Padding {
-	#[inline]
-	fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
-		loop {
-			let mut buf = [0; 8192];
-			if reader.read(&mut buf[..])? == 0 { break; }
-		}
-		Ok(Self {})
-	}
-}