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/* vi: set sw=4 ts=4: */
/* nc: mini-netcat - built from the ground up for LRP
*
* Copyright (C) 1998, 1999 Charles P. Wright
* Copyright (C) 1998 Dave Cinege
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include "busybox.h"
/* Lots of small differences in features
* when compared to "standard" nc
*/
static void timeout(int signum)
{
bb_error_msg_and_die("timed out");
}
int nc_main(int argc, char **argv);
int nc_main(int argc, char **argv)
{
/* sfd sits _here_ only because of "repeat" option (-l -l). */
int sfd = sfd; /* for gcc */
int cfd = 0;
unsigned lport = 0;
SKIP_NC_SERVER(const) unsigned do_listen = 0;
SKIP_NC_EXTRA (const) unsigned wsecs = 0;
SKIP_NC_EXTRA (const) unsigned delay = 0;
SKIP_NC_EXTRA (const int execparam = 0;)
USE_NC_EXTRA (char **execparam = NULL;)
len_and_sockaddr *lsa;
fd_set readfds, testfds;
int opt; /* must be signed (getopt returns -1) */
if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
/* getopt32 is _almost_ usable:
** it cannot handle "... -e prog -prog-opt" */
while ((opt = getopt(argc, argv,
"" USE_NC_SERVER("lp:") USE_NC_EXTRA("w:i:f:e:") )) > 0
) {
if (ENABLE_NC_SERVER && opt=='l') USE_NC_SERVER(do_listen++);
else if (ENABLE_NC_SERVER && opt=='p') {
USE_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
}
else if (ENABLE_NC_EXTRA && opt=='w') USE_NC_EXTRA( wsecs = xatou(optarg));
else if (ENABLE_NC_EXTRA && opt=='i') USE_NC_EXTRA( delay = xatou(optarg));
else if (ENABLE_NC_EXTRA && opt=='f') USE_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"). */
USE_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[arvc] (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();
}
argv += optind; /* ... here! */
argc -= optind;
// -l and -f don't mix
if (do_listen && cfd) bb_show_usage();
// Listen or file modes need zero arguments, client mode needs 2
if (do_listen || cfd) {
if (argc) bb_show_usage();
} else {
if (!argc || argc > 2) bb_show_usage();
}
} else {
if (argc != 3) bb_show_usage();
argc--;
argv++;
}
if (wsecs) {
signal(SIGALRM, timeout);
alarm(wsecs);
}
if (!cfd) {
if (do_listen) {
/* create_and_bind_stream_or_die(NULL, lport)
* would've work wonderfully, but we need
* to know lsa */
sfd = xsocket_stream(&lsa);
if (lport)
set_nport(lsa, htons(lport));
setsockopt_reuseaddr(sfd);
xbind(sfd, &lsa->sa, lsa->len);
xlisten(sfd, do_listen); /* can be > 1 */
/* If we didn't specify a port number,
* query and print it after listen() */
if (!lport) {
socklen_t addrlen = lsa->len;
getsockname(sfd, &lsa->sa, &addrlen);
lport = get_nport(&lsa->sa);
fdprintf(2, "%d\n", ntohs(lport));
}
fcntl(sfd, F_SETFD, FD_CLOEXEC);
accept_again:
cfd = accept(sfd, NULL, 0);
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);
}
}
if (wsecs) {
alarm(0);
signal(SIGALRM, SIG_DFL);
}
/* -e given? */
if (execparam) {
signal(SIGCHLD, SIG_IGN);
// With more than one -l, repeatedly act as server.
if (do_listen > 1 && vfork()) {
/* parent */
// This is a bit weird as cleanup goes, since we wind up with no
// stdin/stdout/stderr. But it's small and shouldn't hurt anything.
// We check for cfd == 0 above.
logmode = LOGMODE_NONE;
close(0);
close(1);
close(2);
goto accept_again;
}
/* child (or main thread if no multiple -l) */
if (cfd) {
dup2(cfd, 0);
close(cfd);
}
dup2(0, 1);
dup2(0, 2);
USE_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
/* Don't print stuff or it will go over the wire.... */
_exit(127);
}
// Select loop copying stdin to cfd, and cfd to stdout.
FD_ZERO(&readfds);
FD_SET(cfd, &readfds);
FD_SET(STDIN_FILENO, &readfds);
for (;;) {
int fd;
int ofd;
int nread;
testfds = readfds;
if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
bb_perror_msg_and_die("select");
for (fd = 0; fd < FD_SETSIZE; fd++) {
if (FD_ISSET(fd, &testfds)) {
nread = safe_read(fd, bb_common_bufsiz1,
sizeof(bb_common_bufsiz1));
if (fd == cfd) {
if (nread < 1)
exit(0);
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, 1);
FD_CLR(STDIN_FILENO, &readfds);
}
ofd = cfd;
}
xwrite(ofd, bb_common_bufsiz1, nread);
if (delay > 0) sleep(delay);
}
}
}
}
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