Introduce InvoiceRequestReceived Event

1. This event will be triggered when user enables manual handling of
   BOLT12 Messages.
2. With this event they can do some preprocessing on their end to make
   sure if they want to continue with this inbound payment.
3. For example, this can be used by the user to do the currency
   conversion on their end and respond to invoice request accordingly.

Author: shaavan

lightning/src/events/mod.rs

@@ -27,6 +27,7 @@ use crate::ln::features::ChannelTypeFeatures;
 use crate::ln::msgs;
 use crate::ln::types::{ChannelId, PaymentPreimage, PaymentHash, PaymentSecret};
 use crate::offers::invoice::Bolt12Invoice;
+use crate::offers::invoice_request::InvoiceRequest;
 use crate::onion_message::messenger::Responder;
 use crate::routing::gossip::NetworkUpdate;
 use crate::routing::router::{BlindedTail, Path, RouteHop, RouteParameters};
@@ -820,6 +821,23 @@ pub enum Event {
 		/// Sockets for connecting to the node.
 		addresses: Vec<msgs::SocketAddress>,
 	},
+
+	/// Event triggered when manual handling is enabled, and an invoice request is received.
+	InvoiceRequestReceived {
+		/// The invoice request to pay.
+		invoice_request: InvoiceRequest,
+		/// The context of the [`BlindedMessagePath`] used to send the invoice request.
+		///
+		/// [`BlindedMessagePath`]: crate::blinded_path::message::BlindedMessagePath
+		context: Option<OffersContext>,
+		/// A responder for replying with an [`InvoiceError`] if needed.
+		///
+		/// `None` if the invoice wasn't sent with a reply path.
+		///
+		/// [`InvoiceError`]: crate::offers::invoice_error::InvoiceError
+		responder: Option<Responder>,
+	},
+
 	/// Indicates a [`Bolt12Invoice`] in response to an [`InvoiceRequest`] or a [`Refund`] was
 	/// received.
 	///
@@ -1740,6 +1758,14 @@ impl Writeable for Event {
 					(8, former_temporary_channel_id, required),
 				});
 			},
+			&Event::InvoiceRequestReceived { ref invoice_request, ref context, ref responder } => {
+				44u8.write(writer)?;
+				write_tlv_fields!(writer, {
+					(0, invoice_request, required),
+					(2, context, option),
+					(4, responder, option),
+				});
+			},
 			// Note that, going forward, all new events must only write data inside of
 			// `write_tlv_fields`. Versions 0.0.101+ will ignore odd-numbered events that write
 			// data via `write_tlv_fields`.
@@ -2234,6 +2260,21 @@ impl MaybeReadable for Event {
 					former_temporary_channel_id: former_temporary_channel_id.0.unwrap(),
 				}))
 			},
+			44u8 => {
+				let mut f = || {
+					_init_and_read_len_prefixed_tlv_fields!(reader, {
+						(0, invoice_request, required),
+						(2, context, option),
+						(4, responder, option),
+					});
+					Ok(Some(Event::InvoiceRequestReceived {
+						invoice_request: invoice_request.0.unwrap(),
+						context,
+						responder,
+					}))
+				};
+				f()
+			},
 			// Versions prior to 0.0.100 did not ignore odd types, instead returning InvalidValue.
 			// Version 0.0.100 failed to properly ignore odd types, possibly resulting in corrupt
 			// reads.

lightning/src/ln/channelmanager.rs

@@ -11038,6 +11038,14 @@ where
 
 		match message {
 			OffersMessage::InvoiceRequest(invoice_request) => {
+				if self.default_configuration.manually_handle_bolt12_messages {
+					let event = Event::InvoiceRequestReceived {
+						invoice_request, context, responder,
+					};
+					self.pending_events.lock().unwrap().push_back((event, None));
+					return None;
+				}
+
 				let responder = match responder {
 					Some(responder) => responder,
 					None => return None,

lightning/src/offers/invoice_request.rs

@@ -595,7 +595,6 @@ impl AsRef<TaggedHash> for UnsignedInvoiceRequest {
 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 /// [`Offer`]: crate::offers::offer::Offer
 #[derive(Clone, Debug)]
-#[cfg_attr(test, derive(PartialEq))]
 pub struct InvoiceRequest {
 	pub(super) bytes: Vec<u8>,
 	pub(super) contents: InvoiceRequestContents,
@@ -1145,6 +1144,14 @@ impl TryFrom<Vec<u8>> for InvoiceRequest {
 	}
 }
 
+impl PartialEq for InvoiceRequest {
+	fn eq(&self, other: &Self) -> bool {
+		self.bytes.eq(&other.bytes)
+	}
+}
+
+impl Eq for InvoiceRequest {}
+
 impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
 	type Error = Bolt12SemanticError;