280 lines
7.9 KiB
C
280 lines
7.9 KiB
C
/* vi: set sw=4 ts=4: */
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/* nc: mini-netcat - built from the ground up for LRP
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*
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* Copyright (C) 1998, 1999 Charles P. Wright
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* Copyright (C) 1998 Dave Cinege
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#include "libbb.h"
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//config:config NC
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//config: bool "nc"
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//config: default y
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//config: help
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//config: A simple Unix utility which reads and writes data across network
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//config: connections.
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//config:
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//config:config NC_SERVER
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//config: bool "Netcat server options (-l)"
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//config: default y
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//config: depends on NC
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//config: help
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//config: Allow netcat to act as a server.
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//config:
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//config:config NC_EXTRA
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//config: bool "Netcat extensions (-eiw and -f FILE)"
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//config: default y
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//config: depends on NC
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//config: help
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//config: Add -e (support for executing the rest of the command line after
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//config: making or receiving a successful connection), -i (delay interval for
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//config: lines sent), -w (timeout for initial connection).
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//config:
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//config:config NC_110_COMPAT
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//config: bool "Netcat 1.10 compatibility (+2.5k)"
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//config: default n # off specially for Rob
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//config: depends on NC
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//config: help
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//config: This option makes nc closely follow original nc-1.10.
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//config: The code is about 2.5k bigger. It enables
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//config: -s ADDR, -n, -u, -v, -o FILE, -z options, but loses
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//config: busybox-specific extensions: -f FILE.
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#if ENABLE_NC_110_COMPAT
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# include "nc_bloaty.c"
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#else
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//usage:#if !ENABLE_NC_110_COMPAT
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//usage:
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//usage:#if ENABLE_NC_SERVER || ENABLE_NC_EXTRA
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//usage:#define NC_OPTIONS_STR "\n"
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//usage:#else
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//usage:#define NC_OPTIONS_STR
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//usage:#endif
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//usage:
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//usage:#define nc_trivial_usage
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//usage: IF_NC_EXTRA("[-iN] [-wN] ")IF_NC_SERVER("[-l] [-p PORT] ")
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//usage: "["IF_NC_EXTRA("-f FILE|")"IPADDR PORT]"IF_NC_EXTRA(" [-e PROG]")
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//usage:#define nc_full_usage "\n\n"
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//usage: "Open a pipe to IP:PORT" IF_NC_EXTRA(" or FILE")
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//usage: NC_OPTIONS_STR
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//usage: IF_NC_SERVER(
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//usage: "\n -l Listen mode, for inbound connects"
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//usage: IF_NC_EXTRA(
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//usage: "\n (use -ll with -e for persistent server)"
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//usage: )
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//usage: "\n -p PORT Local port"
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//usage: )
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//usage: IF_NC_EXTRA(
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//usage: "\n -w SEC Connect timeout"
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//usage: "\n -i SEC Delay interval for lines sent"
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//usage: "\n -f FILE Use file (ala /dev/ttyS0) instead of network"
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//usage: "\n -e PROG Run PROG after connect"
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//usage: )
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//usage:
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//usage:#define nc_notes_usage ""
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//usage: IF_NC_EXTRA(
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//usage: "To use netcat as a terminal emulator on a serial port:\n\n"
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//usage: "$ stty 115200 -F /dev/ttyS0\n"
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//usage: "$ stty raw -echo -ctlecho && nc -f /dev/ttyS0\n"
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//usage: )
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//usage:
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//usage:#define nc_example_usage
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//usage: "$ nc foobar.somedomain.com 25\n"
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//usage: "220 foobar ESMTP Exim 3.12 #1 Sat, 15 Apr 2000 00:03:02 -0600\n"
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//usage: "help\n"
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//usage: "214-Commands supported:\n"
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//usage: "214- HELO EHLO MAIL RCPT DATA AUTH\n"
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//usage: "214 NOOP QUIT RSET HELP\n"
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//usage: "quit\n"
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//usage: "221 foobar closing connection\n"
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//usage:
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//usage:#endif
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/* Lots of small differences in features
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* when compared to "standard" nc
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*/
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static void timeout(int signum UNUSED_PARAM)
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{
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bb_error_msg_and_die("timed out");
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}
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int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int nc_main(int argc, char **argv)
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{
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/* sfd sits _here_ only because of "repeat" option (-l -l). */
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int sfd = sfd; /* for gcc */
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int cfd = 0;
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unsigned lport = 0;
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IF_NOT_NC_SERVER(const) unsigned do_listen = 0;
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IF_NOT_NC_EXTRA (const) unsigned wsecs = 0;
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IF_NOT_NC_EXTRA (const) unsigned delay = 0;
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IF_NOT_NC_EXTRA (const int execparam = 0;)
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IF_NC_EXTRA (char **execparam = NULL;)
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fd_set readfds, testfds;
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int opt; /* must be signed (getopt returns -1) */
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if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
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/* getopt32 is _almost_ usable:
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** it cannot handle "... -e PROG -prog-opt" */
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while ((opt = getopt(argc, argv,
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"" IF_NC_SERVER("lp:") IF_NC_EXTRA("w:i:f:e:") )) > 0
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) {
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if (ENABLE_NC_SERVER && opt == 'l')
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IF_NC_SERVER(do_listen++);
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else if (ENABLE_NC_SERVER && opt == 'p')
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IF_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
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else if (ENABLE_NC_EXTRA && opt == 'w')
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IF_NC_EXTRA( wsecs = xatou(optarg));
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else if (ENABLE_NC_EXTRA && opt == 'i')
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IF_NC_EXTRA( delay = xatou(optarg));
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else if (ENABLE_NC_EXTRA && opt == 'f')
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IF_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
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else if (ENABLE_NC_EXTRA && opt == 'e' && optind <= argc) {
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/* We cannot just 'break'. We should let getopt finish.
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** Or else we won't be able to find where
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** 'host' and 'port' params are
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** (think "nc -w 60 host port -e PROG"). */
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IF_NC_EXTRA(
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char **p;
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// +2: one for progname (optarg) and one for NULL
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execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
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p = execparam;
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*p++ = optarg;
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while (optind < argc) {
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*p++ = argv[optind++];
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}
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)
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/* optind points to argv[argc] (NULL) now.
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** FIXME: we assume that getopt will not count options
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** possibly present on "-e PROG ARGS" and will not
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** include them into final value of optind
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** which is to be used ... */
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} else bb_show_usage();
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}
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argv += optind; /* ... here! */
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argc -= optind;
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// -l and -f don't mix
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if (do_listen && cfd) bb_show_usage();
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// File mode needs need zero arguments, listen mode needs zero or one,
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// client mode needs one or two
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if (cfd) {
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if (argc) bb_show_usage();
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} else if (do_listen) {
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if (argc > 1) bb_show_usage();
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} else {
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if (!argc || argc > 2) bb_show_usage();
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}
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} else {
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if (argc != 3) bb_show_usage();
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argc--;
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argv++;
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}
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if (wsecs) {
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signal(SIGALRM, timeout);
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alarm(wsecs);
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}
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if (!cfd) {
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if (do_listen) {
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sfd = create_and_bind_stream_or_die(argv[0], lport);
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xlisten(sfd, do_listen); /* can be > 1 */
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#if 0 /* nc-1.10 does not do this (without -v) */
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/* If we didn't specify a port number,
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* query and print it after listen() */
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if (!lport) {
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len_and_sockaddr lsa;
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lsa.len = LSA_SIZEOF_SA;
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getsockname(sfd, &lsa.u.sa, &lsa.len);
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lport = get_nport(&lsa.u.sa);
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fdprintf(2, "%d\n", ntohs(lport));
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}
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#endif
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close_on_exec_on(sfd);
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accept_again:
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cfd = accept(sfd, NULL, 0);
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if (cfd < 0)
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bb_perror_msg_and_die("accept");
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if (!execparam)
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close(sfd);
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} else {
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cfd = create_and_connect_stream_or_die(argv[0],
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argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0);
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}
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}
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if (wsecs) {
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alarm(0);
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/* Non-ignored signals revert to SIG_DFL on exec anyway */
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/*signal(SIGALRM, SIG_DFL);*/
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}
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/* -e given? */
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if (execparam) {
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pid_t pid;
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/* With more than one -l, repeatedly act as server */
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if (do_listen > 1 && (pid = xvfork()) != 0) {
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/* parent */
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/* prevent zombies */
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signal(SIGCHLD, SIG_IGN);
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close(cfd);
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goto accept_again;
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}
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/* child, or main thread if only one -l */
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xmove_fd(cfd, 0);
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xdup2(0, 1);
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/*xdup2(0, 2); - original nc 1.10 does this, we don't */
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IF_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
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bb_perror_msg_and_die("can't execute '%s'", execparam[0]);
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}
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/* Select loop copying stdin to cfd, and cfd to stdout */
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FD_ZERO(&readfds);
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FD_SET(cfd, &readfds);
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FD_SET(STDIN_FILENO, &readfds);
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for (;;) {
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int fd;
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int ofd;
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int nread;
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testfds = readfds;
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if (select(cfd + 1, &testfds, NULL, NULL, NULL) < 0)
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bb_perror_msg_and_die("select");
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#define iobuf bb_common_bufsiz1
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fd = STDIN_FILENO;
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while (1) {
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if (FD_ISSET(fd, &testfds)) {
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nread = safe_read(fd, iobuf, sizeof(iobuf));
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if (fd == cfd) {
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if (nread < 1)
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exit(EXIT_SUCCESS);
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ofd = STDOUT_FILENO;
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} else {
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if (nread < 1) {
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/* Close outgoing half-connection so they get EOF,
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* but leave incoming alone so we can see response */
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shutdown(cfd, 1);
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FD_CLR(STDIN_FILENO, &readfds);
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}
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ofd = cfd;
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}
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xwrite(ofd, iobuf, nread);
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if (delay > 0)
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sleep(delay);
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}
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if (fd == cfd)
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break;
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fd = cfd;
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}
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}
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}
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#endif
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