json input support, some shutdown fixes. json needs cleanup.

adsbus/json.c

@@ -14,6 +14,16 @@
 
 #include "json.h"
 
+struct json_parser_state {
+	struct packet_mlat_state mlat_state;
+	uint16_t mlat_timestamp_mhz;
+	uint64_t mlat_timestamp_max;
+	uint32_t rssi_max;
+	bool have_header;
+};
+
+static json_t *json_prev = NULL;
+
 static void json_serialize_to_buf(json_t *obj, struct buf *buf) {
 	assert(json_dump_callback(obj, json_buf_append_callback, buf, 0) == 0);
 	json_decref(obj);
@@ -60,7 +70,36 @@ static void json_serialize_mode_s_long(struct packet *packet, struct buf *buf) {
 	json_serialize_to_buf(out, buf);
 }
 
+static bool json_parse_common(json_t *in, struct packet *packet, struct json_parser_state *state) {
+	if (!state->have_header) {
+		return false;
+	}
+
+	json_t *source_id = json_object_get(in, "source_id");
+	if (!source_id || !json_is_string(source_id)) {
+		return false;
+	}
+	packet->source_id = json_string_value(source_id);
+
+	json_t *mlat_timestamp = json_object_get(in, "mlat_timestamp");
+	if (mlat_timestamp && json_is_integer(mlat_timestamp)) {
+		packet->mlat_timestamp = packet_mlat_timestamp_scale_in(
+				json_integer_value(mlat_timestamp),
+				state->mlat_timestamp_max,
+				state->mlat_timestamp_mhz,
+				&state->mlat_state);
+	}
+
+	json_t *rssi = json_object_get(in, "rssi");
+	if (rssi && json_is_integer(rssi)) {
+		packet->rssi = packet_rssi_scale_in(json_integer_value(rssi), state->rssi_max);
+	}
+
+	return true;
+}
+
 void json_init() {
+	assert(sizeof(struct json_parser_state) <= PARSER_STATE_LEN);
 	assert(JSON_INTEGER_IS_LONG_LONG);
 
 	size_t seed;
@@ -68,6 +107,114 @@ void json_init() {
 	json_object_seed(seed);
 }
 
+void json_cleanup() {
+	if (json_prev) {
+		json_decref(json_prev);
+	}
+}
+
+bool json_parse(struct buf *buf, struct packet *packet, void *state_in) {
+	struct json_parser_state *state = (struct json_parser_state *) state_in;
+
+	if (json_prev) {
+		json_decref(json_prev);
+		json_prev = NULL;
+	}
+
+	json_error_t err;
+	json_t *in = json_loadb(buf_at(buf, 0), buf->length, JSON_DISABLE_EOF_CHECK | JSON_REJECT_DUPLICATES, &err);
+	if (!in) {
+		return false;
+	}
+	if (!json_is_object(in)) {
+		json_decref(in);
+		return false;
+	}
+	json_t *type = json_object_get(in, "type");
+	if (!type || !json_is_string(type)) {
+		json_decref(in);
+		return false;
+	}
+	const char *type_str = json_string_value(type);
+	if (!strcmp(type_str, "header")) {
+		json_t *mlat_timestamp_mhz = json_object_get(in, "mlat_timestamp_mhz");
+		if (!mlat_timestamp_mhz || !json_is_integer(mlat_timestamp_mhz)) {
+			json_decref(in);
+			return false;
+		}
+		state->mlat_timestamp_mhz = json_integer_value(mlat_timestamp_mhz);
+
+		json_t *mlat_timestamp_max = json_object_get(in, "mlat_timestamp_max");
+		if (!mlat_timestamp_max || !json_is_integer(mlat_timestamp_max)) {
+			json_decref(in);
+			return false;
+		}
+		state->mlat_timestamp_max = json_integer_value(mlat_timestamp_max);
+
+		json_t *rssi_max = json_object_get(in, "rssi_max");
+		if (!rssi_max || !json_is_integer(rssi_max)) {
+			json_decref(in);
+			return false;
+		}
+		state->rssi_max = json_integer_value(rssi_max);
+
+		json_t *json_server_id = json_object_get(in, "server_id");
+		if (!json_server_id || !json_is_string(json_server_id)) {
+			json_decref(in);
+			return false;
+		}
+		const char *server_id_str = json_string_value(json_server_id);
+		if (!strcmp(server_id_str, server_id)) {
+			fprintf(stderr, "R %s: Attempt to receive json data from our own server ID (%s); loop!\n", packet->source_id, server_id);
+			json_decref(in);
+			return false;
+		}
+
+		fprintf(stderr, "R %s: Connected to server ID: %s\n", packet->source_id, server_id_str);
+
+		state->have_header = true;
+		packet->type = PACKET_TYPE_NONE;
+	} else if (!strcmp(type_str, "Mode-S short")) {
+		if (!json_parse_common(in, packet, state)) {
+			json_decref(in);
+			return false;
+		}
+
+		json_t *payload = json_object_get(in, "payload");
+		if (!payload || !json_is_string(payload) || json_string_length(payload) != 14) {
+			json_decref(in);
+			return false;
+		}
+
+		hex_to_bin(packet->payload, json_string_value(payload), 7);
+		packet->type = PACKET_TYPE_MODE_S_SHORT;
+	} else if (!strcmp(type_str, "Mode-S long")) {
+		if (!json_parse_common(in, packet, state)) {
+			json_decref(in);
+			return false;
+		}
+
+		json_t *payload = json_object_get(in, "payload");
+		if (!payload || !json_is_string(payload) || json_string_length(payload) != 28) {
+			json_decref(in);
+			return false;
+		}
+
+		hex_to_bin(packet->payload, json_string_value(payload), 14);
+		packet->type = PACKET_TYPE_MODE_S_LONG;
+	} else {
+		json_decref(in);
+		return false;
+	}
+
+	buf_consume(buf, err.position);
+	while (buf->length && (buf_chr(buf, 0) == '\r' || buf_chr(buf, 0) == '\n')) {
+		buf_consume(buf, 1);
+	}
+	json_prev = in;
+	return true;
+}
+
 void json_serialize(struct packet *packet, struct buf *buf) {
 	if (!packet) {
 		json_hello(buf);
@@ -75,13 +222,16 @@ void json_serialize(struct packet *packet, struct buf *buf) {
 	}
 
 	switch (packet->type) {
-		case MODE_S_SHORT:
+		case PACKET_TYPE_MODE_S_SHORT:
 			json_serialize_mode_s_short(packet, buf);
 			break;
 
-		case MODE_S_LONG:
+		case PACKET_TYPE_MODE_S_LONG:
 			json_serialize_mode_s_long(packet, buf);
 			break;
+
+		default:
+			break;
 	}
 }