busybox/networking/nc.c

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/* vi: set sw=4 ts=4: */
/* nc: mini-netcat - built from the ground up for LRP
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*
* Copyright (C) 1998, 1999 Charles P. Wright
* Copyright (C) 1998 Dave Cinege
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*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config NC
//config: bool "nc (11 kb)"
//config: default y
//config: help
//config: A simple Unix utility which reads and writes data across network
//config: connections.
//config:
//config:config NC_SERVER
//config: bool "Netcat server options (-l)"
//config: default y
//config: depends on NC
//config: help
//config: Allow netcat to act as a server.
//config:
//config:config NC_EXTRA
//config: bool "Netcat extensions (-eiw and -f FILE)"
//config: default y
//config: depends on NC
//config: help
//config: Add -e (support for executing the rest of the command line after
//config: making or receiving a successful connection), -i (delay interval for
//config: lines sent), -w (timeout for initial connection).
//config:
//config:config NC_110_COMPAT
//config: bool "Netcat 1.10 compatibility (+2.5k)"
//config: default n # off specially for Rob
//config: depends on NC
//config: help
//config: This option makes nc closely follow original nc-1.10.
//config: The code is about 2.5k bigger. It enables
//config: -s ADDR, -n, -u, -v, -o FILE, -z options, but loses
//config: busybox-specific extensions: -f FILE.
//applet:IF_NC(APPLET(nc, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_NC) += nc.o
#include "libbb.h"
#include "common_bufsiz.h"
#if ENABLE_NC_110_COMPAT
# include "nc_bloaty.c"
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#else
//usage:#if !ENABLE_NC_110_COMPAT
//usage:
//usage:#if ENABLE_NC_SERVER || ENABLE_NC_EXTRA
//usage:#define NC_OPTIONS_STR "\n"
//usage:#else
//usage:#define NC_OPTIONS_STR
//usage:#endif
//usage:
//usage:#define nc_trivial_usage
//usage: IF_NC_EXTRA("[-iN] [-wN] ")IF_NC_SERVER("[-l] [-p PORT] ")
//usage: "["IF_NC_EXTRA("-f FILE|")"IPADDR PORT]"IF_NC_EXTRA(" [-e PROG]")
//usage:#define nc_full_usage "\n\n"
//usage: "Open a pipe to IP:PORT" IF_NC_EXTRA(" or FILE")
//usage: NC_OPTIONS_STR
//usage: IF_NC_SERVER(
//usage: "\n -l Listen mode, for inbound connects"
//usage: IF_NC_EXTRA(
//usage: "\n (use -ll with -e for persistent server)"
//usage: )
//usage: "\n -p PORT Local port"
//usage: )
//usage: IF_NC_EXTRA(
//usage: "\n -w SEC Connect timeout"
//usage: "\n -i SEC Delay interval for lines sent"
//usage: "\n -f FILE Use file (ala /dev/ttyS0) instead of network"
//usage: "\n -e PROG Run PROG after connect"
//usage: )
//usage:
//usage:#define nc_notes_usage ""
//usage: IF_NC_EXTRA(
//usage: "To use netcat as a terminal emulator on a serial port:\n\n"
//usage: "$ stty 115200 -F /dev/ttyS0\n"
//usage: "$ stty raw -echo -ctlecho && nc -f /dev/ttyS0\n"
//usage: )
//usage:
//usage:#define nc_example_usage
//usage: "$ nc foobar.somedomain.com 25\n"
//usage: "220 foobar ESMTP Exim 3.12 #1 Sat, 15 Apr 2000 00:03:02 -0600\n"
//usage: "help\n"
//usage: "214-Commands supported:\n"
//usage: "214- HELO EHLO MAIL RCPT DATA AUTH\n"
//usage: "214 NOOP QUIT RSET HELP\n"
//usage: "quit\n"
//usage: "221 foobar closing connection\n"
//usage:
//usage:#endif
/* Lots of small differences in features
* when compared to "standard" nc
*/
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static void timeout(int signum UNUSED_PARAM)
{
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bb_error_msg_and_die("timed out");
}
int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int nc_main(int argc, char **argv)
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{
/* sfd sits _here_ only because of "repeat" option (-l -l). */
int sfd = sfd; /* for gcc */
int cfd = 0;
unsigned lport = 0;
IF_NOT_NC_SERVER(const) unsigned do_listen = 0;
IF_NOT_NC_EXTRA (const) unsigned wsecs = 0;
IF_NOT_NC_EXTRA (const) unsigned delay = 0;
IF_NOT_NC_EXTRA (const int execparam = 0;)
IF_NC_EXTRA (char **execparam = NULL;)
struct pollfd pfds[2];
int opt; /* must be signed (getopt returns -1) */
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if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
/* getopt32 is _almost_ usable:
** it cannot handle "... -e PROG -prog-opt" */
while ((opt = getopt(argc, argv,
"" IF_NC_SERVER("lp:") IF_NC_EXTRA("w:i:f:e:") )) > 0
) {
if (ENABLE_NC_SERVER && opt == 'l')
IF_NC_SERVER(do_listen++);
else if (ENABLE_NC_SERVER && opt == 'p')
IF_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
else if (ENABLE_NC_EXTRA && opt == 'w')
IF_NC_EXTRA( wsecs = xatou(optarg));
else if (ENABLE_NC_EXTRA && opt == 'i')
IF_NC_EXTRA( delay = xatou(optarg));
else if (ENABLE_NC_EXTRA && opt == 'f')
IF_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
else if (ENABLE_NC_EXTRA && opt == 'e' && optind <= argc) {
/* We cannot just 'break'. We should let getopt finish.
** Or else we won't be able to find where
** 'host' and 'port' params are
** (think "nc -w 60 host port -e PROG"). */
IF_NC_EXTRA(
char **p;
// +2: one for progname (optarg) and one for NULL
execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
p = execparam;
*p++ = optarg;
while (optind < argc) {
*p++ = argv[optind++];
}
)
/* optind points to argv[argc] (NULL) now.
** FIXME: we assume that getopt will not count options
** possibly present on "-e PROG ARGS" and will not
** include them into final value of optind
** which is to be used ... */
} else bb_show_usage();
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}
argv += optind; /* ... here! */
argc -= optind;
// -l and -f don't mix
if (do_listen && cfd) bb_show_usage();
// File mode needs need zero arguments, listen mode needs zero or one,
// client mode needs one or two
if (cfd) {
if (argc) bb_show_usage();
} else if (do_listen) {
if (argc > 1) bb_show_usage();
} else {
if (!argc || argc > 2) bb_show_usage();
}
} else {
if (argc != 3) bb_show_usage();
argc--;
argv++;
}
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if (wsecs) {
signal(SIGALRM, timeout);
alarm(wsecs);
}
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if (!cfd) {
if (do_listen) {
sfd = create_and_bind_stream_or_die(argv[0], lport);
xlisten(sfd, do_listen); /* can be > 1 */
#if 0 /* nc-1.10 does not do this (without -v) */
/* If we didn't specify a port number,
* query and print it after listen() */
if (!lport) {
len_and_sockaddr lsa;
lsa.len = LSA_SIZEOF_SA;
getsockname(sfd, &lsa.u.sa, &lsa.len);
lport = get_nport(&lsa.u.sa);
fdprintf(2, "%d\n", ntohs(lport));
}
#endif
close_on_exec_on(sfd);
accept_again:
cfd = accept(sfd, NULL, 0);
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if (cfd < 0)
bb_perror_msg_and_die("accept");
if (!execparam)
close(sfd);
} else {
cfd = create_and_connect_stream_or_die(argv[0],
argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0);
}
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}
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if (wsecs) {
alarm(0);
/* Non-ignored signals revert to SIG_DFL on exec anyway */
/*signal(SIGALRM, SIG_DFL);*/
}
/* -e given? */
if (execparam) {
pid_t pid;
/* With more than one -l, repeatedly act as server */
if (do_listen > 1 && (pid = xvfork()) != 0) {
/* parent */
/* prevent zombies */
signal(SIGCHLD, SIG_IGN);
close(cfd);
goto accept_again;
}
/* child, or main thread if only one -l */
xmove_fd(cfd, 0);
xdup2(0, 1);
/*xdup2(0, 2); - original nc 1.10 does this, we don't */
IF_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
IF_NC_EXTRA(bb_perror_msg_and_die("can't execute '%s'", execparam[0]);)
}
/* loop copying stdin to cfd, and cfd to stdout */
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pfds[0].fd = STDIN_FILENO;
pfds[0].events = POLLIN;
pfds[1].fd = cfd;
pfds[1].events = POLLIN;
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#define iobuf bb_common_bufsiz1
setup_common_bufsiz();
for (;;) {
int fdidx;
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int ofd;
int nread;
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if (safe_poll(pfds, 2, -1) < 0)
bb_perror_msg_and_die("poll");
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fdidx = 0;
while (1) {
if (pfds[fdidx].revents) {
nread = safe_read(pfds[fdidx].fd, iobuf, COMMON_BUFSIZE);
if (fdidx != 0) {
if (nread < 1)
exit(EXIT_SUCCESS);
ofd = STDOUT_FILENO;
} else {
if (nread < 1) {
/* Close outgoing half-connection so they get EOF,
* but leave incoming alone so we can see response */
shutdown(cfd, SHUT_WR);
pfds[0].fd = -1;
}
ofd = cfd;
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}
xwrite(ofd, iobuf, nread);
if (delay > 0)
sleep(delay);
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}
if (fdidx == 1)
break;
fdidx++;
}
}
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}
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#endif