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 Charles P. Wright
0.0.1 6K It works.
0.0.2 5K Smaller and you can also check the exit condition if you wish.
0.0.3 Uses select()
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19980918 Busy Boxed! Dave Cinege
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19990512 Uses Select. Charles P. Wright
19990513 Fixes stdin stupidity and uses buffers. Charles P. Wright
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Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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#include <unistd.h>
#include <signal.h>
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#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/ioctl.h>
#include "busybox.h"
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static void timeout(int signum)
{
bb_error_msg_and_die("Timed out");
}
int nc_main(int argc, char **argv)
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{
int do_listen = 0, lport = 0, delay = 0, wsecs = 0, tmpfd, opt, sfd, x;
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#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
char *pr00gie = NULL;
#endif
struct sockaddr_in address;
struct hostent *hostinfo;
fd_set readfds, testfds;
while ((opt = getopt(argc, argv, "lp:i:e:w:")) > 0) {
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switch (opt) {
case 'l':
do_listen++;
break;
case 'p':
lport = bb_lookup_port(optarg, "tcp", 0);
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break;
case 'i':
delay = atoi(optarg);
break;
#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
case 'e':
pr00gie = optarg;
break;
#endif
case 'w':
wsecs = atoi(optarg);
break;
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default:
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bb_show_usage();
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}
}
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if ((do_listen && optind != argc) || (!do_listen && optind + 2 != argc))
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bb_show_usage();
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sfd = bb_xsocket(AF_INET, SOCK_STREAM, 0);
x = 1;
if (setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof (x)) == -1)
bb_perror_msg_and_die("reuseaddr");
address.sin_family = AF_INET;
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if (wsecs) {
signal(SIGALRM, timeout);
alarm(wsecs);
}
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if (lport != 0) {
memset(&address.sin_addr, 0, sizeof(address.sin_addr));
address.sin_port = lport;
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bb_xbind(sfd, (struct sockaddr *) &address, sizeof(address));
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}
if (do_listen) {
socklen_t addrlen = sizeof(address);
bb_xlisten(sfd, 1);
if ((tmpfd = accept(sfd, (struct sockaddr *) &address, &addrlen)) < 0)
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bb_perror_msg_and_die("accept");
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close(sfd);
sfd = tmpfd;
} else {
hostinfo = xgethostbyname(argv[optind]);
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address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
address.sin_port = bb_lookup_port(argv[optind+1], "tcp", 0);
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if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
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bb_perror_msg_and_die("connect");
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}
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if (wsecs) {
alarm(0);
signal(SIGALRM, SIG_DFL);
}
#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
/* -e given? */
if (pr00gie) {
dup2(sfd, 0);
close(sfd);
dup2(0, 1);
dup2(0, 2);
execl(pr00gie, pr00gie, NULL);
/* Don't print stuff or it will go over the wire.... */
_exit(-1);
}
#endif /* CONFIG_NC_GAPING_SECURITY_HOLE */
FD_ZERO(&readfds);
FD_SET(sfd, &readfds);
FD_SET(STDIN_FILENO, &readfds);
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while (1) {
int fd;
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int ofd;
int nread;
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testfds = readfds;
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if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
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bb_perror_msg_and_die("select");
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for (fd = 0; fd < FD_SETSIZE; fd++) {
if (FD_ISSET(fd, &testfds)) {
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if ((nread = safe_read(fd, bb_common_bufsiz1,
sizeof(bb_common_bufsiz1))) < 0)
{
bb_perror_msg_and_die(bb_msg_read_error);
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}
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if (fd == sfd) {
if (nread == 0)
exit(0);
ofd = STDOUT_FILENO;
} else {
if (nread <= 0) {
shutdown(sfd, 1 /* send */ );
close(STDIN_FILENO);
FD_CLR(STDIN_FILENO, &readfds);
}
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ofd = sfd;
}
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if (bb_full_write(ofd, bb_common_bufsiz1, nread) < 0)
bb_perror_msg_and_die(bb_msg_write_error);
if (delay > 0) {
sleep(delay);
}
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}
}
}
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}