API: Add payment fields(if not NULL) into return value when sendpay fails

pPayment field includes the basic information of the payment, so the return valves of 'sendpay_success()' and 'sendpay_fail()' should include this field.
Note "immediate_routing_failure" is before payment creation, and for this case, return won't include payment fields.

lightningd/pay.c

@@ -142,10 +142,14 @@ json_add_routefail_info(struct json_stream *js,
 }
 
 void json_sendpay_fail_fields(struct json_stream *js,
+			      const struct wallet_payment *payment,
 			      int pay_errcode,
 			      const u8 *onionreply,
 			      const struct routing_failure *fail)
 {
+	/* "immediate_routing_failure" is before payment creation. */
+	if (payment)
+		json_add_payment_fields(js, payment);
 	if (pay_errcode == PAY_UNPARSEABLE_ONION)
 		json_add_hex_talarr(js, "onionreply", onionreply);
 	else
@@ -161,6 +165,7 @@ void json_sendpay_fail_fields(struct json_stream *js,
 /* onionreply used if pay_errcode == PAY_UNPARSEABLE_ONION */
 static struct command_result *
 sendpay_fail(struct command *cmd,
+	     const struct wallet_payment *payment,
 	     int pay_errcode,
 	     const u8 *onionreply,
 	     const struct routing_failure *fail,
@@ -181,6 +186,7 @@ sendpay_fail(struct command *cmd,
 	data = json_stream_fail(cmd, pay_errcode,
 				errmsg);
 	json_sendpay_fail_fields(data,
+				 payment,
 				 pay_errcode,
 				 onionreply,
 				 fail);
@@ -202,6 +208,7 @@ json_sendpay_in_progress(struct command *cmd,
 
 static void tell_waiters_failed(struct lightningd *ld,
 				const struct sha256 *payment_hash,
+				const struct wallet_payment *payment,
 				int pay_errcode,
 				const u8 *onionreply,
 				const struct routing_failure *fail,
@@ -215,7 +222,8 @@ static void tell_waiters_failed(struct lightningd *ld,
 		if (!sha256_eq(payment_hash, &pc->payment_hash))
 			continue;
 
-		sendpay_fail(pc->cmd, pay_errcode, onionreply, fail, details);
+		sendpay_fail(pc->cmd, payment,
+			     pay_errcode, onionreply, fail, details);
 	}
 }
 
@@ -510,8 +518,8 @@ void payment_failed(struct lightningd *ld, const struct htlc_out *hout,
 				    failmsg,
 				    fail ? fail->channel_dir : 0);
 
-	tell_waiters_failed(ld, &hout->payment_hash, pay_errcode,
+	tell_waiters_failed(ld, &hout->payment_hash, payment,
-			    hout->failuremsg, fail, failmsg);
+			    pay_errcode, hout->failuremsg, fail, failmsg);
 }
 
 /* Wait for a payment. If cmd is deleted, then json_waitsendpay_on_resolve
@@ -567,7 +575,9 @@ static struct command_result *wait_payment(struct lightningd *ld,
 					    "Payment failure reason unknown");
 		} else if (failonionreply) {
 			/* failed to parse returned onion error */
-			return sendpay_fail(cmd, PAY_UNPARSEABLE_ONION,
+			return sendpay_fail(cmd,
+					    payment,
+					    PAY_UNPARSEABLE_ONION,
 					    failonionreply,
 					    NULL, faildetail);
 		} else {
@@ -583,6 +593,7 @@ static struct command_result *wait_payment(struct lightningd *ld,
 			/* FIXME: We don't store this! */
 			fail->msg = NULL;
 			return sendpay_fail(cmd,
+					    payment,
 					    faildestperm
 					    ? PAY_DESTINATION_PERM_FAIL
 					    : PAY_TRY_OTHER_ROUTE,
@@ -721,8 +732,8 @@ send_payment(struct lightningd *ld,
 						 &route[0].channel_id,
 						 &channel->peer->id);
 
-		return sendpay_fail(cmd, PAY_TRY_OTHER_ROUTE, NULL,
+		return sendpay_fail(cmd, payment, PAY_TRY_OTHER_ROUTE,
-				    fail, "First peer not ready");
+				    NULL, fail, "First peer not ready");
 	}
 
 	/* Copy channels used along the route. */

lightningd/pay.h

@@ -26,6 +26,7 @@ void json_add_payment_fields(struct json_stream *response,
 
 /* This json will be also used in 'sendpay_failure' notifictaion. */
 void json_sendpay_fail_fields(struct json_stream *js,
+			      const struct wallet_payment *t,
 			      int pay_errcode,
 			      const u8 *onionreply,
 			      const struct routing_failure *fail);