Fix server_id overflow due to utf8 blowup in json.

adsbus/json.c

@@ -99,6 +99,10 @@ static bool json_parse_header(json_t *in, struct packet *packet, struct json_par
 	state->mlat_timestamp_max = (uint64_t) mlat_timestamp_max;
 	state->rssi_max = (uint32_t) rssi_max;
 
+	if (!packet_validate_id((const uint8_t *) json_server_id)) {
+		return false;
+	}
+
 	if (!strcmp(json_server_id, (const char *) server_id)) {
 		fprintf(stderr, "R %s: Attempt to receive json data from our own server ID (%s); loop!\n", packet->source_id, server_id);
 		return false;

adsbus/packet.c

@@ -1,4 +1,8 @@
 #include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "uuid.h"
 
 #include "packet.h"
 
@@ -47,8 +51,24 @@ uint32_t packet_rssi_scale_out(uint32_t value, uint32_t max) {
 }
 
 void packet_sanity_check(const struct packet *packet) {
-	assert(packet->source_id);
+	assert(packet_validate_id(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);
 }
+
+bool packet_validate_id(const uint8_t *id) {
+	if (!id) {
+		return false;
+	}
+	for (size_t i = 0; i < UUID_LEN; i++) {
+		uint8_t c = id[i];
+		if (c == 0) {
+			return true;
+		}
+		if (c < 32 || c > 126) {
+			return false;
+		}
+	}
+	return false;
+}

adsbus/packet.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <stdbool.h>
 #include <stdint.h>
 
 #define PACKET_DATA_LEN_MAX 14
@@ -34,3 +35,4 @@ uint32_t __attribute__ ((warn_unused_result)) packet_rssi_scale_in(uint32_t, uin
 uint32_t __attribute__ ((warn_unused_result)) packet_rssi_scale_out(uint32_t, uint32_t);
 
 void packet_sanity_check(const struct packet *);
+bool __attribute__ ((warn_unused_result)) packet_validate_id(const uint8_t *);

adsbus/proto.c

@@ -9,6 +9,7 @@
 #include "buf.h"
 #include "packet.h"
 #include "server.h"
+#include "uuid.h"
 
 #include "adsb.pb-c.h"
 #include "proto.h"
@@ -99,6 +100,9 @@ static bool proto_parse_packet(AdsbPacket *in, struct packet *packet, struct pro
 		return false;
 	}
 
+	if (!packet_validate_id((const uint8_t *) in->source_id)) {
+		return false;
+	}
 	packet->source_id = (uint8_t *) in->source_id;
 	memcpy(packet->payload, in->payload.data, len);