f - limit number of invoice requests

Author: jkczyz

lightning/src/ln/channelmanager.rs

@@ -7201,7 +7201,11 @@ where
 			};
 			pending_offers_messages.push(message);
 		} else {
-			for path in offer.paths() {
+			// Send as many invoice requests as there are paths in the offer (with an upper bound).
+			// Using only one path could result in a failure if the path no longer exists. But only
+			// one invoice for a given payment id will be paid, even if more than one is received.
+			const REQUEST_LIMIT: usize = 10;
+			for path in offer.paths().into_iter().take(REQUEST_LIMIT) {
 				let message = PendingOnionMessage {
 					contents: OffersMessage::InvoiceRequest(invoice_request.clone()),
 					destination: Destination::BlindedPath(path.clone()),