Support checking that a static invoice matches an outbound invreq.

Useful for ensuring that an inbound static invoice matches one of our outbound
invreqs, otherwise it is an unexpected invoice and should be ignored and not
paid.

Author: valentinewallace

lightning/src/offers/invoice_request.rs

@@ -840,6 +840,11 @@ impl InvoiceRequest {
 	invoice_request_accessors!(self, self.contents);
 	invoice_request_respond_with_explicit_signing_pubkey_methods!(self, self, InvoiceBuilder<ExplicitSigningPubkey>);
 	invoice_request_verify_method!(self, Self);
+
+	#[cfg(async_payments)]
+	pub(super) fn bytes(&self) -> &Vec<u8> {
+		&self.bytes
+	}
 }
 
 #[cfg(c_bindings)]

lightning/src/offers/merkle.rs

@@ -249,6 +249,7 @@ impl<'a> TlvStream<'a> {
 }
 
 /// A slice into a [`TlvStream`] for a record.
+#[derive(Eq, PartialEq)]
 pub(super) struct TlvRecord<'a> {
 	pub(super) r#type: u64,
 	type_bytes: &'a [u8],

lightning/src/offers/static_invoice.rs

@@ -20,12 +20,13 @@ use crate::offers::invoice::{
 	InvoiceTlvStream, InvoiceTlvStreamRef,
 };
 use crate::offers::invoice_macros::{invoice_accessors_common, invoice_builder_methods_common};
+use crate::offers::invoice_request::InvoiceRequest;
 use crate::offers::merkle::{
-	self, SignError, SignFn, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash,
+	self, SignError, SignFn, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, TlvStream,
 };
 use crate::offers::nonce::Nonce;
 use crate::offers::offer::{
-	Amount, Offer, OfferContents, OfferTlvStream, OfferTlvStreamRef, Quantity,
+	Amount, Offer, OfferContents, OfferTlvStream, OfferTlvStreamRef, Quantity, OFFER_TYPES,
 };
 use crate::offers::parse::{Bolt12ParseError, Bolt12SemanticError, ParsedMessage};
 use crate::util::ser::{CursorReadable, Iterable, WithoutLength, Writeable, Writer};
@@ -312,6 +313,16 @@ impl StaticInvoice {
 	pub fn signature(&self) -> Signature {
 		self.signature
 	}
+
+	pub(crate) fn from_same_offer(&self, invreq: &InvoiceRequest) -> bool {
+		let invoice_offer_tlv_stream = TlvStream::new(&self.bytes)
+			.range(OFFER_TYPES)
+			.map(|tlv_record| tlv_record.record_bytes);
+		let invreq_offer_tlv_stream = TlvStream::new(invreq.bytes())
+			.range(OFFER_TYPES)
+			.map(|tlv_record| tlv_record.record_bytes);
+		invoice_offer_tlv_stream.eq(invreq_offer_tlv_stream)
+	}
 }
 
 impl InvoiceContents {