buffer overflow in dns.c pointed out by Matus Harvan, also strncpy cleanups

src/common.h

@@ -28,6 +28,8 @@
 #define MAX(a,b) ((a)>(b)?(a):(b))
 #endif
 
+#define QUERY_NAME_SIZE 256
+
 struct packet 
 {
 	int len;		/* Total packet length */
@@ -37,7 +39,7 @@ struct packet
 };
 
 struct query {
-	char name[258];
+	char name[QUERY_NAME_SIZE];
 	short type;
 	short id;
 	struct sockaddr from;

src/dns.c

@@ -61,7 +61,7 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
 	
 		name = 0xc000 | ((p - buf) & 0x3fff);
 
-		putname(&p, 256, q->name);
+		putname(&p, sizeof(q->name), q->name);
 
 		putshort(&p, q->type);
 		putshort(&p, C_IN);
@@ -78,7 +78,7 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
 		header->qdcount = htons(1);
 		header->arcount = htons(1);
 	
-		putname(&p, 256, data);
+		putname(&p, datalen, data);
 
 		putshort(&p, q->type);
 		putshort(&p, C_IN);
@@ -101,11 +101,11 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
 int
 dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, size_t packetlen)
 {
+	char name[QUERY_NAME_SIZE];
 	char rdata[4*1024];
 	HEADER *header;
 	short qdcount;
 	short ancount;
-	char name[255];
 	uint32_t ttl;
 	short class;
 	short type;
@@ -190,7 +190,7 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
 		}
 
 		readname(packet, packetlen, &data, name, sizeof(name) - 1);
-		name[256] = 0;
+		name[sizeof(name)-1] = '\0';
 		readshort(packet, &data, &type);
 		readshort(packet, &data, &class);
 
@@ -199,7 +199,8 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
 			break;
 		}
 
-		strncpy(q->name, name, 257);
+		strncpy(q->name, name, sizeof(q->name));
+		q->name[sizeof(q->name) - 1] = '\0';
 		q->type = type;
 		q->id = id;
 

src/iodine.c

@@ -654,8 +654,8 @@ main(int argc, char **argv)
 			device = optarg;
 			break;
 		case 'P':
-			strncpy(password, optarg, 32);
-			password[32] = 0;
+			strncpy(password, optarg, sizeof(password));
+			password[sizeof(password)-1] = 0;
 			
 			/* XXX: find better way of cleaning up ps(1) */
 			memset(optarg, 0, strlen(optarg)); 

src/iodined.c

@@ -495,8 +495,8 @@ main(int argc, char **argv)
 			}
 			break;
 		case 'P':
-			strncpy(password, optarg, 32);
-			password[32] = 0;
+			strncpy(password, optarg, sizeof(password));
+			password[sizeof(password)-1] = 0;
 			
 			/* XXX: find better way of cleaning up ps(1) */
 			memset(optarg, 0, strlen(optarg)); 

src/tun.c

@@ -58,7 +58,9 @@ open_tun(const char *tun_device)
 
 	if (tun_device != NULL) {
 		strncpy(ifreq.ifr_name, tun_device, IFNAMSIZ);
+		ifreq.ifr_name[IFNAMSIZ-1] = '\0';
 		strncpy(if_name, tun_device, sizeof(if_name));
+		if_name[sizeof(if_name)-1] = '\0';
 
 		if (ioctl(tun_fd, TUNSETIFF, (void *) &ifreq) != -1) {
 			printf("Opened %s\n", ifreq.ifr_name);
@@ -102,6 +104,7 @@ open_tun(const char *tun_device)
 	if (tun_device != NULL) {
 		snprintf(tun_name, sizeof(tun_name), "/dev/%s", tun_device);
 		strncpy(if_name, tun_device, sizeof(if_name));
+		if_name[sizeof(if_name)-1] = '\0';
 
 		if ((tun_fd = open(tun_name, O_RDWR)) < 0) {
 			warn("open_tun: %s: %s", tun_name, strerror(errno));
@@ -140,7 +143,7 @@ close_tun(int tun_fd)
 }
 
 int 
-write_tun(int tun_fd, char *data, int len) 
+write_tun(int tun_fd, char *data, size_t len) 
 {
 #if defined (FREEBSD) || defined (DARWIN) || defined(NETBSD)
 	data += 4;
@@ -166,8 +169,8 @@ write_tun(int tun_fd, char *data, int len)
 	return 0;
 }
 
-int 
-read_tun(int tun_fd, char *buf, int len) 
+ssize_t
+read_tun(int tun_fd, char *buf, size_t len) 
 {
 #if defined (FREEBSD) || defined (DARWIN) || defined(NETBSD)
 	/* FreeBSD/Darwin/NetBSD has no header */
@@ -213,20 +216,20 @@ tun_setip(const char *ip)
 }
 
 int 
-tun_setmtu(const int mtu)
+tun_setmtu(const size_t mtu)
 {
 	char cmdline[512];
 
 	if (mtu > 200 && mtu < 1500) {
 		snprintf(cmdline, sizeof(cmdline), 
-				"/sbin/ifconfig %s mtu %d",
+				"/sbin/ifconfig %s mtu %ld",
 				if_name,
 				mtu);
 		
-		printf("Setting MTU of %s to %d\n", if_name, mtu);
+		printf("Setting MTU of %s to %ld\n", if_name, mtu);
 		return system(cmdline);
 	} else {
-		warn("MTU out of range: %d\n", mtu);
+		warn("MTU out of range: %ld\n", mtu);
 	}
 
 	return 1;

src/tun.h

@@ -19,9 +19,9 @@
 
 int open_tun(const char *);
 void close_tun(int);
-int write_tun(int, char *, int);
-int read_tun(int, char *, int);
+int write_tun(int, char *, size_t);
+ssize_t read_tun(int, char *, size_t);
 int tun_setip(const char *);
-int tun_setmtu(const int);
+int tun_setmtu(const size_t);
 
 #endif /* _TUN_H_ */