Use static greeting buffers.

adsbus/adsbus.c

@@ -115,6 +115,7 @@ int main(int argc, char *argv[]) {
 
 	beast_init();
 	json_init();
+	proto_init();
 	stats_init();
 
 	if (!parse_opts(argc, argv)) {

adsbus/airspy_adsb.c

@@ -151,10 +151,6 @@ bool airspy_adsb_parse(struct buf *buf, struct packet *packet, void *state_in) {
 }
 
 void airspy_adsb_serialize(struct packet *packet, struct buf *buf) {
-	if (!packet) {
-		return;
-	}
-
 	switch (packet->type) {
 		case PACKET_TYPE_NONE:
 			break;

adsbus/beast.c

@@ -180,10 +180,6 @@ bool beast_parse(struct buf *buf, struct packet *packet, void *state_in) {
 }
 
 void beast_serialize(struct packet *packet, struct buf *buf) {
-	if (!packet) {
-		return;
-	}
-
 	switch (packet->type) {
 		case PACKET_TYPE_NONE:
 			break;

adsbus/json.c

@@ -25,6 +25,7 @@ struct json_parser_state {
 };
 
 static json_t *json_prev = NULL;
+static struct buf json_hello_buf = BUF_INIT;
 
 static void json_serialize_to_buf(json_t *obj, struct buf *buf) {
 	assert(json_dump_callback(obj, json_buf_append_callback, buf, 0) == 0);
@@ -32,19 +33,6 @@ static void json_serialize_to_buf(json_t *obj, struct buf *buf) {
 	buf_chr(buf, buf->length++) = '\n';
 }
 
-static void json_hello(struct buf *buf) {
-	json_t *hello = json_pack(
-			"{s:s, s:s, s:s, s:s, s:I, s:I, s:I}",
-			"type", "header",
-			"magic", JSON_MAGIC,
-			"server_version", server_version,
-			"server_id", server_id,
-			"mlat_timestamp_mhz", (json_int_t) PACKET_MLAT_MHZ,
-			"mlat_timestamp_max", (json_int_t) PACKET_MLAT_MAX,
-			"rssi_max", (json_int_t) PACKET_RSSI_MAX);
-	json_serialize_to_buf(hello, buf);
-}
-
 static void json_add_common(struct packet *packet, json_t *obj) {
 	json_object_set_new(obj, "type", json_string(packet_type_names[packet->type]));
 	json_object_set_new(obj, "source_id", json_string((const char *) packet->source_id));
@@ -192,6 +180,17 @@ void json_init() {
 	size_t seed;
 	rand_fill(&seed, sizeof(seed));
 	json_object_seed(seed);
+
+	json_t *hello = json_pack(
+			"{s:s, s:s, s:s, s:s, s:I, s:I, s:I}",
+			"type", "header",
+			"magic", JSON_MAGIC,
+			"server_version", server_version,
+			"server_id", server_id,
+			"mlat_timestamp_mhz", (json_int_t) PACKET_MLAT_MHZ,
+			"mlat_timestamp_max", (json_int_t) PACKET_MLAT_MAX,
+			"rssi_max", (json_int_t) PACKET_RSSI_MAX);
+	json_serialize_to_buf(hello, &json_hello_buf);
 }
 
 void json_cleanup() {
@@ -248,11 +247,6 @@ bool json_parse(struct buf *buf, struct packet *packet, void *state_in) {
 }
 
 void json_serialize(struct packet *packet, struct buf *buf) {
-	if (!packet) {
-		json_hello(buf);
-		return;
-	}
-
 	switch (packet->type) {
 		case PACKET_TYPE_NONE:
 			break;
@@ -267,6 +261,10 @@ void json_serialize(struct packet *packet, struct buf *buf) {
 	}
 }
 
+void json_hello(struct buf **buf) {
+	*buf = &json_hello_buf;
+}
+
 int json_buf_append_callback(const char *buffer, size_t size, void *data) {
 	struct buf *buf = data;
 	if (buf->length + size + 1 > BUF_LEN_MAX) {

adsbus/json.h

@@ -9,5 +9,6 @@ void json_init(void);
 void json_cleanup(void);
 bool __attribute__ ((warn_unused_result)) json_parse(struct buf *, struct packet *, void *);
 void json_serialize(struct packet *, struct buf *);
+void json_hello(struct buf **);
 
 int json_buf_append_callback(const char *, size_t, void *);

adsbus/proto.c

@@ -29,6 +29,7 @@ struct proto_parser_state {
 };
 
 static Adsb *proto_prev = NULL;
+static struct buf proto_hello_buf = BUF_INIT;
 
 static void proto_obj_to_buf(Adsb *wrapper, struct buf *buf) {
 	assert(!buf->length);
@@ -126,6 +127,21 @@ static bool proto_parse_packet(AdsbPacket *in, struct packet *packet, struct pro
 	return true;
 }
 
+void proto_init() {
+	AdsbHeader header = ADSB_HEADER__INIT;
+	header.magic = PROTO_MAGIC;
+	header.server_version = server_version;
+	header.server_id = (char *) server_id;
+	header.mlat_timestamp_mhz = PACKET_MLAT_MHZ;
+	header.mlat_timestamp_max = PACKET_MLAT_MAX;
+	header.rssi_max = PACKET_RSSI_MAX;
+
+	Adsb wrapper = ADSB__INIT;
+	wrapper.header = &header;
+
+	proto_obj_to_buf(&wrapper, &proto_hello_buf);
+}
+
 void proto_cleanup() {
 	if (proto_prev) {
 		adsb__free_unpacked(proto_prev, NULL);
@@ -184,22 +200,6 @@ bool proto_parse(struct buf *buf, struct packet *packet, void *state_in) {
 }
 
 void proto_serialize(struct packet *packet, struct buf *buf) {
-	if (!packet) {
-		AdsbHeader header = ADSB_HEADER__INIT;
-		header.magic = PROTO_MAGIC;
-		header.server_version = server_version;
-		header.server_id = (char *) server_id;
-		header.mlat_timestamp_mhz = PACKET_MLAT_MHZ;
-		header.mlat_timestamp_max = PACKET_MLAT_MAX;
-		header.rssi_max = PACKET_RSSI_MAX;
-
-		Adsb wrapper = ADSB__INIT;
-		wrapper.header = &header;
-
-		proto_obj_to_buf(&wrapper, buf);
-		return;
-	}
-
 	switch (packet->type) {
 		case PACKET_TYPE_NONE:
 			break;
@@ -213,3 +213,7 @@ void proto_serialize(struct packet *packet, struct buf *buf) {
 			break;
 	}
 }
+
+void proto_hello(struct buf **buf) {
+	*buf = &proto_hello_buf;
+}

adsbus/proto.h

@@ -5,6 +5,8 @@
 struct buf;
 struct packet;
 
+void proto_init(void);
 void proto_cleanup(void);
 bool __attribute__ ((warn_unused_result)) proto_parse(struct buf *, struct packet *, void *);
 void proto_serialize(struct packet *, struct buf *);
+void proto_hello(struct buf **);

adsbus/raw.c

@@ -87,10 +87,6 @@ bool raw_parse(struct buf *buf, struct packet *packet, void __attribute__((unuse
 }
 
 void raw_serialize(struct packet *packet, struct buf *buf) {
-	if (!packet) {
-		return;
-	}
-
 	switch (packet->type) {
 		case PACKET_TYPE_NONE:
 			break;

adsbus/send.c

@@ -32,34 +32,42 @@ struct send {
 };
 
 typedef void (*serialize)(struct packet *, struct buf *);
+typedef void (*hello)(struct buf **);
 static struct serializer {
 	char *name;
 	serialize serialize;
+	hello hello;
 	struct list_head send_head;
 } serializers[] = {
 	{
 		.name = "airspy_adsb",
 		.serialize = airspy_adsb_serialize,
+		.hello = NULL,
 	},
 	{
 		.name = "beast",
 		.serialize = beast_serialize,
+		.hello = NULL,
 	},
 	{
 		.name = "json",
 		.serialize = json_serialize,
+		.hello = json_hello,
 	},
 	{
 		.name = "proto",
 		.serialize = proto_serialize,
+		.hello = proto_hello,
 	},
 	{
 		.name = "raw",
 		.serialize = raw_serialize,
+		.hello = NULL,
 	},
 	{
 		.name = "stats",
 		.serialize = stats_serialize,
+		.hello = NULL,
 	},
 };
 #define NUM_SERIALIZERS (sizeof(serializers) / sizeof(*serializers))
@@ -130,8 +138,7 @@ void send_new_wrapper(int fd, void *passthrough, struct peer *on_close) {
 
 void send_hello(struct buf **buf_pp, void *passthrough) {
 	struct serializer *serializer = (struct serializer *) passthrough;
-	// TODO: change API to avoid special-case NULL packet*, and to allow static greetings.
+	serializer->hello(buf_pp);
-	serializer->serialize(NULL, *buf_pp);
 }
 
 void send_write(struct packet *packet) {