*: remove check for errors on getsockaddr in cases we know they can't happen

libbb: make get_sock_lsa use only one getsockaddr syscall, not two

function                                             old     new   delta
get_sock_lsa                                          72     101     +29
do_iplink                                           1151    1137     -14
arping_main                                         1585    1569     -16
dolisten                                             789     755     -34
xrtnl_open                                           161      94     -67

6 files changed, 37 insertions, 31 deletions

diff --git a/libbb/xconnect.c b/libbb/xconnect.c
index 1b4f4f78a..f853e9593 100644
--- a/libbb/xconnect.c
+++ b/libbb/xconnect.c
@@ -37,16 +37,21 @@ int FAST_FUNC setsockopt_bindtodevice(int fd, const char *iface)
 
 len_and_sockaddr* FAST_FUNC get_sock_lsa(int fd)
 {
-	len_and_sockaddr *lsa;
-	socklen_t len = 0;
+	len_and_sockaddr lsa;
+	len_and_sockaddr *lsa_ptr;
 
-	/* Can be optimized to do only one getsockname() */
-	if (getsockname(fd, NULL, &len) != 0)
+	lsa.len = LSA_SIZEOF_SA;
+	if (getsockname(fd, &lsa.u.sa, &lsa.len) != 0)
 		return NULL;
-	lsa = xzalloc(LSA_LEN_SIZE + len);
-	lsa->len = len;
-	getsockname(fd, &lsa->u.sa, &lsa->len);
-	return lsa;
+
+	lsa_ptr = xzalloc(LSA_LEN_SIZE + lsa.len);
+	if (lsa.len > LSA_SIZEOF_SA) { /* rarely (if ever) happens */
+		lsa_ptr->len = lsa.len;
+		getsockname(fd, &lsa_ptr->u.sa, &lsa_ptr->len);
+	} else {
+		memcpy(lsa_ptr, &lsa, LSA_LEN_SIZE + lsa.len);
+	}
+	return lsa_ptr;
 }
 
 void FAST_FUNC xconnect(int s, const struct sockaddr *s_addr, socklen_t addrlen)
diff --git a/networking/arping.c b/networking/arping.c
index 915af3261..ab39c717b 100644
--- a/networking/arping.c
+++ b/networking/arping.c
@@ -348,9 +348,10 @@ int arping_main(int argc UNUSED_PARAM, char **argv)
 			if (setsockopt(probe_fd, SOL_SOCKET, SO_DONTROUTE, &const_int_1, sizeof(const_int_1)) == -1)
 				bb_perror_msg("setsockopt(SO_DONTROUTE)");
 			xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
-			if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1) {
-				bb_perror_msg_and_die("getsockname");
-			}
+			getsockname(probe_fd, (struct sockaddr *) &saddr, &alen);
+			//never happens:
+			//if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1)
+			//	bb_perror_msg_and_die("getsockname");
 			if (saddr.sin_family != AF_INET)
 				bb_error_msg_and_die("no IP address configured");
 			src = saddr.sin_addr;
@@ -365,10 +366,10 @@ int arping_main(int argc UNUSED_PARAM, char **argv)
 
 	{
 		socklen_t alen = sizeof(me);
-
-		if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1) {
-			bb_perror_msg_and_die("getsockname");
-		}
+		getsockname(sock_fd, (struct sockaddr *) &me, &alen);
+		//never happens:
+		//if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1)
+		//	bb_perror_msg_and_die("getsockname");
 	}
 	if (me.sll_halen == 0) {
 		bb_error_msg(err_str, "is not ARPable (no ll address)");
diff --git a/networking/libiproute/iplink.c b/networking/libiproute/iplink.c
index 1e7ee07d2..de7d6407e 100644
--- a/networking/libiproute/iplink.c
+++ b/networking/libiproute/iplink.c
@@ -112,11 +112,11 @@ static int get_address(char *dev, int *htype)
 	me.sll_ifindex = ifr.ifr_ifindex;
 	me.sll_protocol = htons(ETH_P_LOOP);
 	xbind(s, (struct sockaddr*)&me, sizeof(me));
-
 	alen = sizeof(me);
-	if (getsockname(s, (struct sockaddr*)&me, &alen) == -1) {
-		bb_perror_msg_and_die("getsockname");
-	}
+	getsockname(s, (struct sockaddr*)&me, &alen);
+	//never happens:
+	//if (getsockname(s, (struct sockaddr*)&me, &alen) == -1)
+	//	bb_perror_msg_and_die("getsockname");
 	close(s);
 	*htype = me.sll_hatype;
 	return me.sll_halen;
diff --git a/networking/libiproute/libnetlink.c b/networking/libiproute/libnetlink.c
index 6d51d8deb..7ad2de9fa 100644
--- a/networking/libiproute/libnetlink.c
+++ b/networking/libiproute/libnetlink.c
@@ -26,22 +26,23 @@ int FAST_FUNC xrtnl_open(struct rtnl_handle *rth/*, unsigned subscriptions*/)
 {
 	socklen_t addr_len;
 
-	memset(rth, 0, sizeof(rth));
-
+	memset(rth, 0, sizeof(*rth));
 	rth->fd = xsocket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
-
-	memset(&rth->local, 0, sizeof(rth->local));
 	rth->local.nl_family = AF_NETLINK;
 	/*rth->local.nl_groups = subscriptions;*/
 
 	xbind(rth->fd, (struct sockaddr*)&rth->local, sizeof(rth->local));
 	addr_len = sizeof(rth->local);
+	getsockname(rth->fd, (struct sockaddr*)&rth->local, &addr_len);
+
+/* too much paranoia
 	if (getsockname(rth->fd, (struct sockaddr*)&rth->local, &addr_len) < 0)
 		bb_perror_msg_and_die("getsockname");
 	if (addr_len != sizeof(rth->local))
 		bb_error_msg_and_die("wrong address length %d", addr_len);
 	if (rth->local.nl_family != AF_NETLINK)
 		bb_error_msg_and_die("wrong address family %d", rth->local.nl_family);
+*/
 	rth->seq = time(NULL);
 	return 0;
 }
diff --git a/networking/libiproute/libnetlink.h b/networking/libiproute/libnetlink.h
index e5fee4dd8..11a4a100a 100644
--- a/networking/libiproute/libnetlink.h
+++ b/networking/libiproute/libnetlink.h
@@ -10,8 +10,7 @@
 
 PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
 
-struct rtnl_handle
-{
+struct rtnl_handle {
 	int			fd;
 	struct sockaddr_nl	local;
 	struct sockaddr_nl	peer;
diff --git a/networking/nc_bloaty.c b/networking/nc_bloaty.c
index 47940e9b3..efe831ec3 100644
--- a/networking/nc_bloaty.c
+++ b/networking/nc_bloaty.c
@@ -278,9 +278,9 @@ static void dolisten(void)
 	 random unknown port is probably not very useful without "netstat". */
 	if (o_verbose) {
 		char *addr;
-		rr = getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
-		if (rr < 0)
-			bb_perror_msg_and_die("getsockname after bind");
+		getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
+		//if (rr < 0)
+		//	bb_perror_msg_and_die("getsockname after bind");
 		addr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
 		fprintf(stderr, "listening on %s ...\n", addr);
 		free(addr);
@@ -359,9 +359,9 @@ create new one, and bind() it. TODO */
 		 doing a listen-on-any on a multihomed machine.  This allows one to
 		 offer different services via different alias addresses, such as the
 		 "virtual web site" hack. */
-		rr = getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
-		if (rr < 0)
-			bb_perror_msg_and_die("getsockname after accept");
+		getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
+		//if (rr < 0)
+		//	bb_perror_msg_and_die("getsockname after accept");
 	}
 
 	if (o_verbose) {