Store the source HumanReadableName in InvoiceRequestFields

When we receive a payment to an offer we issued resolved with a
human readable name, it may have been resolved using a wildcard
DNS entry which we want to map to a specific recipient account
locally. To do this, we need the human readable name from the
`InvoiceRequest` in the `PaymentClaim{able,ed}`, which we pipe
through here using `InvoiceRequestFields`.

Author: TheBlueMatt

lightning/src/events/mod.rs

@@ -124,6 +124,10 @@ pub enum PaymentPurpose {
 		/// The context of the payment such as information about the corresponding [`Offer`] and
 		/// [`InvoiceRequest`].
 		///
+		/// This includes the Human Readable Name which the sender indicated they were paying to,
+		/// for possible recipient disambiguation if you're using a single wildcard DNS entry to
+		/// resolve to many recipients.
+		///
 		/// [`Offer`]: crate::offers::offer::Offer
 		/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 		payment_context: Bolt12OfferContext,

lightning/src/ln/offers_tests.rs

@@ -564,6 +564,7 @@ fn creates_and_pays_for_offer_using_two_hop_blinded_path() {
 			payer_signing_pubkey: invoice_request.payer_signing_pubkey(),
 			quantity: None,
 			payer_note_truncated: None,
+			human_readable_name: None,
 		},
 	});
 	assert_eq!(invoice_request.amount_msats(), None);
@@ -724,6 +725,7 @@ fn creates_and_pays_for_offer_using_one_hop_blinded_path() {
 			payer_signing_pubkey: invoice_request.payer_signing_pubkey(),
 			quantity: None,
 			payer_note_truncated: None,
+			human_readable_name: None,
 		},
 	});
 	assert_eq!(invoice_request.amount_msats(), None);
@@ -844,6 +846,7 @@ fn pays_for_offer_without_blinded_paths() {
 			payer_signing_pubkey: invoice_request.payer_signing_pubkey(),
 			quantity: None,
 			payer_note_truncated: None,
+			human_readable_name: None,
 		},
 	});
 
@@ -1110,6 +1113,7 @@ fn creates_and_pays_for_offer_with_retry() {
 			payer_signing_pubkey: invoice_request.payer_signing_pubkey(),
 			quantity: None,
 			payer_note_truncated: None,
+			human_readable_name: None,
 		},
 	});
 	assert_eq!(invoice_request.amount_msats(), None);
@@ -1174,6 +1178,7 @@ fn pays_bolt12_invoice_asynchronously() {
 			payer_signing_pubkey: invoice_request.payer_signing_pubkey(),
 			quantity: None,
 			payer_note_truncated: None,
+			human_readable_name: None,
 		},
 	});
 
@@ -1263,6 +1268,7 @@ fn creates_offer_with_blinded_path_using_unannounced_introduction_node() {
 			payer_signing_pubkey: invoice_request.payer_signing_pubkey(),
 			quantity: None,
 			payer_note_truncated: None,
+			human_readable_name: None,
 		},
 	});
 	assert_ne!(invoice_request.payer_signing_pubkey(), bob_id);

lightning/src/offers/invoice_request.rs

@@ -966,6 +966,7 @@ impl VerifiedInvoiceRequest {
 			quantity: *quantity,
 			payer_note_truncated: payer_note.clone()
 				.map(|mut s| { s.truncate(PAYER_NOTE_LIMIT); UntrustedString(s) }),
+			human_readable_name: self.source_human_readable_name().clone(),
 		}
 	}
 }
@@ -1233,6 +1234,9 @@ pub struct InvoiceRequestFields {
 	/// A payer-provided note which will be seen by the recipient and reflected back in the invoice
 	/// response. Truncated to [`PAYER_NOTE_LIMIT`] characters.
 	pub payer_note_truncated: Option<UntrustedString>,
+
+	/// The Human Readable Name which the sender indicated they were paying to.
+	pub human_readable_name: Option<HumanReadableName>,
 }
 
 /// The maximum number of characters included in [`InvoiceRequestFields::payer_note_truncated`].
@@ -1242,6 +1246,7 @@ impl Writeable for InvoiceRequestFields {
 	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 		write_tlv_fields!(writer, {
 			(0, self.payer_signing_pubkey, required),
+			(1, self.human_readable_name, option),
 			(2, self.quantity.map(|v| HighZeroBytesDroppedBigSize(v)), option),
 			(4, self.payer_note_truncated.as_ref().map(|s| WithoutLength(&s.0)), option),
 		});
@@ -1253,6 +1258,7 @@ impl Readable for InvoiceRequestFields {
 	fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 		_init_and_read_len_prefixed_tlv_fields!(reader, {
 			(0, payer_signing_pubkey, required),
+			(1, human_readable_name, option),
 			(2, quantity, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 			(4, payer_note_truncated, (option, encoding: (String, WithoutLength))),
 		});
@@ -1261,6 +1267,7 @@ impl Readable for InvoiceRequestFields {
 			payer_signing_pubkey: payer_signing_pubkey.0.unwrap(),
 			quantity,
 			payer_note_truncated: payer_note_truncated.map(|s| UntrustedString(s)),
+			human_readable_name,
 		})
 	}
 }
@@ -2378,6 +2385,7 @@ mod tests {
 						payer_signing_pubkey: payer_pubkey(),
 						quantity: Some(1),
 						payer_note_truncated: Some(UntrustedString("0".repeat(PAYER_NOTE_LIMIT))),
+						human_readable_name: None,
 					}
 				);