From d6cb3afd9dd90c0b151e7197561b7593e20445e7 Mon Sep 17 00:00:00 2001
From: Ian Gulliver <flamingcow@gmail.com>
Date: Fri, 26 Feb 2016 14:55:43 -0800
Subject: [PATCH] Centralize packet sanity checks, and bound one value that was
 overflowing.

---
 adsbus/json.c   |  2 --
 adsbus/packet.c | 11 ++++++++++-
 adsbus/packet.h |  9 +++++----
 adsbus/send.c   |  2 ++
 4 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/adsbus/json.c b/adsbus/json.c
index d739cd2..80b8019 100644
--- a/adsbus/json.c
+++ b/adsbus/json.c
@@ -57,7 +57,6 @@ static void json_add_common(struct packet *packet, json_t *obj) {
 }
 
 static void json_serialize_mode_s_short(struct packet *packet, struct buf *buf) {
-	assert(packet->mlat_timestamp < PACKET_MLAT_MAX);
 	uint8_t hexbuf[14];
 	hex_from_bin_upper(hexbuf, packet->payload, 7);
 	json_t *out = json_pack("{ss#}", "payload", hexbuf, 14);
@@ -66,7 +65,6 @@ static void json_serialize_mode_s_short(struct packet *packet, struct buf *buf)
 }
 
 static void json_serialize_mode_s_long(struct packet *packet, struct buf *buf) {
-	assert(packet->mlat_timestamp < PACKET_MLAT_MAX);
 	uint8_t hexbuf[28];
 	hex_from_bin_upper(hexbuf, packet->payload, 14);
 	json_t *out = json_pack("{ss#}", "payload", hexbuf, 28);
diff --git a/adsbus/packet.c b/adsbus/packet.c
index 284e688..296b015 100644
--- a/adsbus/packet.c
+++ b/adsbus/packet.c
@@ -1,3 +1,5 @@
+#include <assert.h>
+
 #include "packet.h"
 
 char *packet_type_names[] = {
@@ -29,7 +31,7 @@ static uint64_t packet_mlat_timestamp_scale_width_out(uint64_t timestamp, uint64
 }
 
 uint64_t packet_mlat_timestamp_scale_in(uint64_t timestamp, uint64_t max, uint16_t mhz, struct packet_mlat_state *state) {
-	return packet_mlat_timestamp_scale_mhz_in(packet_mlat_timestamp_scale_width_in(timestamp, max, state), mhz);
+	return packet_mlat_timestamp_scale_mhz_in(packet_mlat_timestamp_scale_width_in(timestamp, max, state), mhz) % PACKET_MLAT_MAX;
 }
 
 uint64_t packet_mlat_timestamp_scale_out(uint64_t timestamp, uint64_t max, uint16_t mhz) {
@@ -43,3 +45,10 @@ uint32_t packet_rssi_scale_in(uint32_t value, uint32_t max) {
 uint32_t packet_rssi_scale_out(uint32_t value, uint32_t max) {
 	return value / (PACKET_RSSI_MAX / max);
 }
+
+void packet_sanity_check(const struct packet *packet) {
+	assert(packet->source_id);
+	assert(packet->type > PACKET_TYPE_NONE && packet->type < NUM_TYPES);
+	assert(packet->mlat_timestamp <= PACKET_MLAT_MAX);
+	assert(packet->rssi <= PACKET_RSSI_MAX);
+}
diff --git a/adsbus/packet.h b/adsbus/packet.h
index 4941603..731c350 100644
--- a/adsbus/packet.h
+++ b/adsbus/packet.h
@@ -27,9 +27,10 @@ struct packet_mlat_state {
 	uint64_t timestamp_generation;
 };
 
-uint64_t packet_mlat_timestamp_scale_in(uint64_t, uint64_t, uint16_t, struct packet_mlat_state *);
-uint64_t packet_mlat_timestamp_scale_out(uint64_t, uint64_t, uint16_t);
+uint64_t __attribute__ ((warn_unused_result)) packet_mlat_timestamp_scale_in(uint64_t, uint64_t, uint16_t, struct packet_mlat_state *);
+uint64_t __attribute__ ((warn_unused_result)) packet_mlat_timestamp_scale_out(uint64_t, uint64_t, uint16_t);
 
-uint32_t packet_rssi_scale_in(uint32_t, uint32_t);
-uint32_t packet_rssi_scale_out(uint32_t, uint32_t);
+uint32_t __attribute__ ((warn_unused_result)) packet_rssi_scale_in(uint32_t, uint32_t);
+uint32_t __attribute__ ((warn_unused_result)) packet_rssi_scale_out(uint32_t, uint32_t);
 
+void packet_sanity_check(const struct packet *);
diff --git a/adsbus/send.c b/adsbus/send.c
index 9400afd..de05ca2 100644
--- a/adsbus/send.c
+++ b/adsbus/send.c
@@ -14,6 +14,7 @@
 #include "buf.h"
 #include "json.h"
 #include "list.h"
+#include "packet.h"
 #include "peer.h"
 #include "proto.h"
 #include "raw.h"
@@ -146,6 +147,7 @@ void send_new_wrapper(int fd, void *passthrough, struct peer *on_close) {
 }
 
 void send_write(struct packet *packet) {
+	packet_sanity_check(packet);
 	for (size_t i = 0; i < NUM_SERIALIZERS; i++) {
 		struct serializer *serializer = &serializers[i];
 		if (list_is_empty(&serializer->send_head)) {