From: Jeffrey Czyz <jkczyz@gmail.com>
Date: Thu, 22 Dec 2022 15:33:41 +0000 (-0600)
Subject: Encoding for TLV stream without signature records
X-Git-Tag: v0.0.114-beta~49^2~8
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=243f4487017f43712ebb1aa76806329f7e147593;p=rust-lightning

Encoding for TLV stream without signature records

When using bytes from an InvoiceRequest to constructing bytes for an
Invoice, any signature TLV records in the bytes must be excluded. Define
a wrapper for encoding such pre-serialized bytes in this manner. This
will allow the forthcoming InvoiceBuilder to construct bytes for an
Invoice properly.
---

diff --git a/lightning/src/offers/merkle.rs b/lightning/src/offers/merkle.rs
index 1a505aae8..9782dc7d1 100644
--- a/lightning/src/offers/merkle.rs
+++ b/lightning/src/offers/merkle.rs
@@ -13,7 +13,7 @@ use bitcoin::hashes::{Hash, HashEngine, sha256};
 use bitcoin::secp256k1::{Message, PublicKey, Secp256k1, self};
 use bitcoin::secp256k1::schnorr::Signature;
 use crate::io;
-use crate::util::ser::{BigSize, Readable};
+use crate::util::ser::{BigSize, Readable, Writeable, Writer};
 
 use crate::prelude::*;
 
@@ -194,14 +194,33 @@ impl<'a> Iterator for TlvStream<'a> {
 	}
 }
 
+/// Encoding for a pre-serialized TLV stream that excludes any signature TLV records.
+///
+/// Panics if the wrapped bytes are not a well-formed TLV stream.
+pub(super) struct WithoutSignatures<'a>(pub &'a Vec<u8>);
+
+impl<'a> Writeable for WithoutSignatures<'a> {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+		let tlv_stream = TlvStream::new(&self.0[..]);
+		for record in tlv_stream.skip_signatures() {
+			writer.write_all(record.record_bytes)?;
+		}
+		Ok(())
+	}
+}
+
 #[cfg(test)]
 mod tests {
+	use super::{TlvStream, WithoutSignatures};
+
 	use bitcoin::hashes::{Hash, sha256};
 	use bitcoin::secp256k1::{KeyPair, Secp256k1, SecretKey};
 	use core::convert::Infallible;
 	use crate::offers::offer::{Amount, OfferBuilder};
 	use crate::offers::invoice_request::InvoiceRequest;
 	use crate::offers::parse::Bech32Encode;
+	use crate::util::ser::Writeable;
 
 	#[test]
 	fn calculates_merkle_root_hash() {
@@ -253,6 +272,36 @@ mod tests {
 		);
 	}
 
+	#[test]
+	fn skips_encoding_signature_tlv_records() {
+		let secp_ctx = Secp256k1::new();
+		let recipient_pubkey = {
+			let secret_key = SecretKey::from_slice(&[41; 32]).unwrap();
+			KeyPair::from_secret_key(&secp_ctx, &secret_key).public_key()
+		};
+		let payer_keys = {
+			let secret_key = SecretKey::from_slice(&[42; 32]).unwrap();
+			KeyPair::from_secret_key(&secp_ctx, &secret_key)
+		};
+
+		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey)
+			.amount_msats(100)
+			.build_unchecked()
+			.request_invoice(vec![0; 8], payer_keys.public_key()).unwrap()
+			.build_unchecked()
+			.sign::<_, Infallible>(|digest| Ok(secp_ctx.sign_schnorr_no_aux_rand(digest, &payer_keys)))
+			.unwrap();
+
+		let mut bytes_without_signature = Vec::new();
+		WithoutSignatures(&invoice_request.bytes).write(&mut bytes_without_signature).unwrap();
+
+		assert_ne!(bytes_without_signature, invoice_request.bytes);
+		assert_eq!(
+			TlvStream::new(&bytes_without_signature).count(),
+			TlvStream::new(&invoice_request.bytes).count() - 1,
+		);
+	}
+
 	impl AsRef<[u8]> for InvoiceRequest {
 		fn as_ref(&self) -> &[u8] {
 			&self.bytes