clang scan-build: fix various build warning

arping: fix dereference of null pointer.
clockdiff: fix assigned value is garbage or undefined warnings.
ninfod: fix dead assignment and use of uninitialized argument value.
ping: fix dead assignment.
rarpd: fix uninitialized argument value.
rdisc: fix uninitialized argument value.
tracepath: fix dereference of null pointer.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

arping.c

@@ -697,7 +697,7 @@ static int event_loop(struct run_state *ctl)
 	uint64_t exp, total_expires = 1;
 
 	unsigned char packet[4096];
-	struct sockaddr_storage from;
+	struct sockaddr_storage from = { 0 };
 	socklen_t addr_len = sizeof(from);
 
 	/* signalfd */

clockdiff.c

@@ -340,7 +340,7 @@ static int measure(struct run_state *ctl)
 		.min1 = 0x7fffffff,
 		.min2 = 0x7fffffff
 	};
-	unsigned char opacket[64];
+	unsigned char opacket[64] = { 0 };
 	struct icmphdr *oicp = (struct icmphdr *)opacket;
 
 	mv.ip = (struct iphdr *)mv.packet;
@@ -527,7 +527,7 @@ int main(int argc, char **argv)
 	if (connect(ctl.sock_raw, (struct sockaddr *)&ctl.server, sizeof(ctl.server)) == -1)
 		error(1, errno, "connect");
 	if (ctl.ip_opt_len) {
-		struct sockaddr_in myaddr;
+		struct sockaddr_in myaddr = { 0 };
 		socklen_t addrlen = sizeof(myaddr);
 		unsigned char rspace[ctl.ip_opt_len];
 

ninfod/ni_ifaddrs.c

@@ -179,7 +179,6 @@ static int nl_getmsg(int sd, uint32_t seq, struct nlmsghdr **nlhp, int *done)
 		}
 		if (read_size == 0)
 			break;
-		nh = (struct nlmsghdr *) buff;
 		for (nh = (struct nlmsghdr *) buff; NLMSG_OK(nh, read_size); nh = (struct nlmsghdr *) NLMSG_NEXT(nh, read_size)) {
 			if ((pid_t) nh->nlmsg_pid != pid || nh->nlmsg_seq != seq)
 				continue;

ninfod/ninfod.c

@@ -677,7 +677,7 @@ int main (int argc, char **argv)
 
 		init_core(0);
 
-		p = malloc(sizeof(*p));
+		p = calloc(1, sizeof(*p));
 		if (!p) {
 			DEBUG(LOG_WARNING, "%s(): failed to allocate packet context; sleep 1 sec.\n",
 			      __func__);

ping6_common.c

@@ -721,8 +721,6 @@ int ping6_run(int argc, char **argv, struct addrinfo *ai, struct socket_st *sock
 	if (!(packet = (unsigned char *)malloc((unsigned int)packlen)))
 		error(2, errno, _("memory allocation failed"));
 
-	hold = 1;
-
 	/* Estimate memory eaten by single packet. It is rough estimate.
 	 * Actually, for small datalen's it depends on kernel side a lot. */
 	hold = datalen+8;

rarpd.c

@@ -428,7 +428,7 @@ void arp_advise(int ifindex, unsigned char *lladdr, int lllen, uint32_t ipaddr)
 void serve_it(int fd)
 {
 	unsigned char buf[1024];
-	struct sockaddr_ll sll;
+	struct sockaddr_ll sll = { 0 };
 	socklen_t sll_len = sizeof(sll);
 	struct arphdr *a = (struct arphdr*)buf;
 	struct rarp_map *rmap;

rdisc.c

@@ -280,7 +280,7 @@ char    *sendaddress, *recvaddress;
 
 int main(int argc, char **argv)
 {
-	struct sockaddr_in from;
+	struct sockaddr_in from = { 0 };
 	char **av = argv;
 	struct sockaddr_in *to = &whereto;
 	struct sockaddr_in joinaddr;

tracepath.c

@@ -518,8 +518,10 @@ int main(int argc, char **argv)
 	sprintf(pbuf, "%u", ctl.base_port);
 
 	status = getaddrinfo(argv[0], pbuf, &hints, &result);
-	if (status)
+	if (status || !result) {
 		error(1, 0, "%s: %s", argv[0], gai_strerror(status));
+		abort();
+	}
 
 	for (ctl.ai = result; ctl.ai; ctl.ai = ctl.ai->ai_next) {
 		if (ctl.ai->ai_family != AF_INET6 && ctl.ai->ai_family != AF_INET)