*: 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) {