libbb: make bb_lookup_port() abort on bad port names

Also, no need to preserve errno

function                                             old     new   delta
.rodata                                           104247  104241      -6
bb_lookup_port                                        97      83     -14
nc_main                                             1039    1018     -21
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-41)             Total: -41 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 4 insertions, 8 deletions

diff --git a/networking/ftpgetput.c b/networking/ftpgetput.c
index 30b3dabd1..4c92f34a1 100644
--- a/networking/ftpgetput.c
+++ b/networking/ftpgetput.c
@@ -290,8 +290,7 @@ static const char ftpgetput_longopts[] ALIGN1 =
 int ftpgetput_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int ftpgetput_main(int argc UNUSED_PARAM, char **argv)
 {
-        const char *port = "ftp";
-        /* socket to ftp server */
+        const char *port = NULL;
 
 #if ENABLE_FTPPUT && !ENABLE_FTPGET
 # define ftp_action ftp_send
diff --git a/networking/nc.c b/networking/nc.c
index 705b7356a..d351bf72a 100644
--- a/networking/nc.c
+++ b/networking/nc.c
@@ -216,7 +216,7 @@ int nc_main(int argc, char **argv)
                                 close(sfd);
                 } else {
                         cfd = create_and_connect_stream_or_die(argv[0],
-                                argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0);
+                                bb_lookup_port(argv[1], "tcp", 0));
                 }
         }
 
diff --git a/networking/nc_bloaty.c b/networking/nc_bloaty.c
index 25b95246f..cfa133eae 100644
--- a/networking/nc_bloaty.c
+++ b/networking/nc_bloaty.c
@@ -813,8 +813,6 @@ int nc_main(int argc UNUSED_PARAM, char **argv)
         //if (option_mask32 & OPT_o) /* hexdump log */
         if (option_mask32 & OPT_p) { /* local source port */
                 o_lport = bb_lookup_port(str_p, o_udpmode ? "udp" : "tcp", 0);
-                if (!o_lport)
-                        bb_error_msg_and_die("bad local port '%s'", str_p);
         }
         //if (option_mask32 & OPT_r) /* randomize various things */
         //if (option_mask32 & OPT_u) /* use UDP */
@@ -827,9 +825,8 @@ int nc_main(int argc UNUSED_PARAM, char **argv)
 
         if (argv[0]) {
                 themaddr = xhost2sockaddr(argv[0],
-                        argv[1]
-                        ? bb_lookup_port(argv[1], o_udpmode ? "udp" : "tcp", 0)
-                        : 0);
+                        bb_lookup_port(argv[1], o_udpmode ? "udp" : "tcp", 0)
+                );
         }
 
         /* create & bind network socket */