Function json_add_halfchan

plugins/topology.c:211–288

To avoid multiple fetches, we represent directions as a bitmap * so we can do two at once. */

/* To avoid multiple fetches, we represent directions as a bitmap
 * so we can do two at once. */
static void json_add_halfchan(struct json_stream *response,
			      struct gossmap *gossmap,
			      const struct node_map *connected,
			      const struct gossmap_chan *c,
			      int dirbits)
{
	struct short_channel_id scid;
	struct node_id node_id[2];
	const u8 *chanfeatures;
	struct amount_sat capacity;
	bool local_disable;

	/* These are channel (not per-direction) properties */
	chanfeatures = gossmap_chan_get_features(tmpctx, gossmap, c);
	scid = gossmap_chan_scid(gossmap, c);
	for (size_t i = 0; i < 2; i++)
		gossmap_node_get_id(gossmap, gossmap_nth_node(gossmap, c, i),
				    &node_id[i]);

	/* This can theoretically happen on partial write races. */
	if (!gossmap_chan_get_capacity(gossmap, c, &capacity))
		capacity = AMOUNT_SAT(0);

	/* Local channels are not "active" unless peer is connected. */
	if (node_id_eq(&node_id[0], &local_id))
		local_disable = !node_map_get(connected, &node_id[1]);
	else if (node_id_eq(&node_id[1], &local_id))
		local_disable = !node_map_get(connected, &node_id[0]);
	else
		local_disable = false;

	for (int dir = 0; dir < 2; dir++) {
		u32 timestamp;
		u8 message_flags, channel_flags;
		u32 fee_base_msat, fee_proportional_millionths;
		struct amount_msat htlc_minimum_msat, htlc_maximum_msat;

		if (!((1 << dir) & dirbits))
			continue;

		if (!gossmap_chan_set(c, dir))
			continue;

		json_object_start(response, NULL);
		json_add_node_id(response, "source", &node_id[dir]);
		json_add_node_id(response, "destination", &node_id[!dir]);
		json_add_short_channel_id(response, "short_channel_id", &scid);
		json_add_bool(response, "public", !c->private);

		gossmap_chan_get_update_details(gossmap, c, dir,
						&timestamp,
						&message_flags,
						&channel_flags,
						&fee_base_msat,
						&fee_proportional_millionths,
						&htlc_minimum_msat,
						&htlc_maximum_msat);