listincoming: deduplicate listed channels

Where an unannounced channel with a private update has been added to the
gossip_store, make sure not to add it as both a public and private
channel.

plugins/topology.c

@@ -535,7 +535,8 @@ static struct amount_msat max_receivable(struct short_channel_id *scid,
 
 static void add_private_channel(struct json_stream *js, const char *buf,
 				const jsmntok_t *channel,
-				struct chanliquidity *liquidity)
+				struct chanliquidity *liquidity,
+				struct short_channel_id *processed_channels)
 {
 	const jsmntok_t *node_id_tok, *scid_tok, *fee_base_tok;
 	const jsmntok_t *fee_ppm_tok, *cltv_tok;
@@ -546,16 +547,30 @@ static void add_private_channel(struct json_stream *js, const char *buf,
 	u32 fee_base, fee_ppm, cltv_delta;
 	struct amount_msat htlc_min, htlc_max;
 	u8 *features;
+
+	scid_tok = json_get_member(buf, channel, "short_channel_id");
+	if (scid_tok) {
+		json_to_short_channel_id(buf, scid_tok, &scid);
+		/* check if we've already used this from the gossmap
+		 * public channels */
+		for (size_t i = 0; i < tal_count(processed_channels); i++) {
+			if (short_channel_id_eq(&scid, &processed_channels[i]))
+				return;
+		}
+	}
+
+	scid_tok = json_get_member(buf, channel, "remote_alias");
+	if (!scid_tok)
+		scid_tok = json_get_member(buf, channel, "short_channel_id");
+	json_to_short_channel_id(buf, scid_tok, &scid);
+
 	json_object_start(js, NULL);
 
 	node_id_tok = json_get_member(buf, channel, "id");
 	assert(node_id_tok);
 	json_to_node_id(buf, node_id_tok, &id);
 	json_add_node_id(js, "id", &id);
 
-	scid_tok = json_get_member(buf, channel, "remote_alias");
-	assert(scid_tok);
-	json_to_short_channel_id(buf, scid_tok, &scid);
 	json_add_short_channel_id(js, "short_channel_id", &scid);
 
 	fee_base_tok = json_get_member(buf, channel, "fee_base");
@@ -605,6 +620,8 @@ static struct command_result *listprivateinbound_done(struct command *cmd,
 	struct json_stream *js;
 	struct gossmap_node *me;
 	struct gossmap *gossmap;
+	struct short_channel_id *processed_channels = tal_arr(cmd,
+					struct short_channel_id, 0);
 	js = jsonrpc_stream_success(cmd);
 
 	json_array_start(js, "incoming");
@@ -658,6 +675,7 @@ static struct command_result *listprivateinbound_done(struct command *cmd,
 		if (peer_features)
 			json_add_hex_talarr(js, "peer_features", peer_features);
 		json_object_end(js);
+		tal_arr_expand(&processed_channels, scid);
 	}
 
 public_done:
@@ -669,10 +687,12 @@ static struct command_result *listprivateinbound_done(struct command *cmd,
 		size_t i;
 
 		json_for_each_arr(i, channel, channels) {
-			add_private_channel(js, buf, channel, liquidity);
+			add_private_channel(js, buf, channel, liquidity,
+					    processed_channels);
 		}
 
 		json_array_end(js);
+		tal_free(processed_channels);
 
 		return command_finished(cmd, js);
 	}