JSON: Warp the process of forward payment json object

Warp this process as a new function: 'void json_format_forwarding_object()'. This function will be used in 'forward_event' next, and can ensure the consistent json object structure for forward_payment between 'listforwards' API and 'forward_event' notification.

lightningd/peer_htlcs.c

@@ -2104,15 +2104,13 @@ static const struct json_command dev_ignore_htlcs = {
 AUTODATA(json_command, &dev_ignore_htlcs);
 #endif /* DEVELOPER */
 
-static void listforwardings_add_forwardings(struct json_stream *response, struct wallet *wallet)
+/* Warp this process to ensure the consistent json object structure
+ * between 'listforwards' API and 'forward_event' notification. */
+void json_format_forwarding_object(struct json_stream *response,
+				   const char *fieldname,
+				   const struct forwarding *cur)
 {
-	const struct forwarding *forwardings;
-	forwardings = wallet_forwarded_payments_get(wallet, tmpctx);
-
-	json_array_start(response, "forwards");
-	for (size_t i=0; i<tal_count(forwardings); i++) {
-		const struct forwarding *cur = &forwardings[i];
-		json_object_start(response, NULL);
+	json_object_start(response, fieldname);
 
 	json_add_hex(response, "payment_hash",
 				    cur->payment_hash,
@@ -2150,6 +2148,18 @@ static void listforwardings_add_forwardings(struct json_stream *response, struct
 		json_add_timeabs(response, "resolved_time", *cur->resolved_time);
 #endif
 	json_object_end(response);
+}
+
+
+static void listforwardings_add_forwardings(struct json_stream *response, struct wallet *wallet)
+{
+	const struct forwarding *forwardings;
+	forwardings = wallet_forwarded_payments_get(wallet, tmpctx);
+
+	json_array_start(response, "forwards");
+	for (size_t i=0; i<tal_count(forwardings); i++) {
+		const struct forwarding *cur = &forwardings[i];
+		json_format_forwarding_object(response, NULL, cur);
 	}
 	json_array_end(response);
 

lightningd/peer_htlcs.h

@@ -14,6 +14,8 @@ struct htlc_out;
 struct htlc_out_map;
 struct htlc_stub;
 struct lightningd;
+struct forwarding;
+struct json_stream;
 
 /* FIXME: Define serialization primitive for this? */
 struct channel_info {
@@ -69,4 +71,8 @@ void htlcs_reconnect(struct lightningd *ld,
 void fulfill_htlc(struct htlc_in *hin, const struct preimage *preimage);
 void fail_htlc(struct htlc_in *hin, enum onion_type failcode);
 
+/* This json process will be both used in 'notify_forward_event()'
+ * and 'listforwardings_add_forwardings()'*/
+void json_format_forwarding_object(struct json_stream *response, const char *fieldname,
+				   const struct forwarding *cur);
 #endif /* LIGHTNING_LIGHTNINGD_PEER_HTLCS_H */