mirror of
https://github.com/sheumann/hush.git
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203 lines
5.2 KiB
C
203 lines
5.2 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 tarball for details.
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*/
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#include "busybox.h"
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static void timeout(int signum)
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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)
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{
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int sfd = 0;
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int cfd = 0;
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SKIP_NC_SERVER(const) unsigned do_listen = 0;
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SKIP_NC_SERVER(const) unsigned lport = 0;
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SKIP_NC_EXTRA (const) unsigned wsecs = 0;
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SKIP_NC_EXTRA (const) unsigned delay = 0;
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SKIP_NC_EXTRA (const int execparam = 0;)
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USE_NC_EXTRA (char **execparam = NULL;)
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struct sockaddr_in address;
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struct hostent *hostinfo;
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fd_set readfds, testfds;
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int opt; /* must be signed (getopt returns -1) */
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memset(&address, 0, sizeof(address));
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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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"" USE_NC_SERVER("lp:") USE_NC_EXTRA("w:i:f:e:") )) > 0
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) {
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if (ENABLE_NC_SERVER && opt=='l') USE_NC_SERVER(do_listen++);
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else if (ENABLE_NC_SERVER && opt=='p') USE_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
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else if (ENABLE_NC_EXTRA && opt=='w') USE_NC_EXTRA( wsecs = xatou(optarg));
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else if (ENABLE_NC_EXTRA && opt=='i') USE_NC_EXTRA( delay = xatou(optarg));
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else if (ENABLE_NC_EXTRA && opt=='f') USE_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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USE_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[arvc] (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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// Listen or file modes need zero arguments, client mode needs 2
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opt = ((do_listen || cfd) ? 0 : 2);
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if (argc != opt)
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bb_show_usage();
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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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sfd = xsocket(AF_INET, SOCK_STREAM, 0);
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fcntl(sfd, F_SETFD, FD_CLOEXEC);
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opt = 1;
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setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
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address.sin_family = AF_INET;
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// Set local port.
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if (lport != 0) {
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address.sin_port = lport;
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xbind(sfd, (struct sockaddr *) &address, sizeof(address));
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}
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if (do_listen) {
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socklen_t addrlen = sizeof(address);
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xlisten(sfd, do_listen);
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// If we didn't specify a port number, query and print it to stderr.
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if (!lport) {
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socklen_t len = sizeof(address);
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getsockname(sfd, &address, &len);
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fdprintf(2, "%d\n", SWAP_BE16(address.sin_port));
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}
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repeatyness:
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cfd = accept(sfd, (struct sockaddr *) &address, &addrlen);
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if (cfd < 0)
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bb_perror_msg_and_die("accept");
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if (!execparam) close(sfd);
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} else {
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hostinfo = xgethostbyname(argv[0]);
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address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
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address.sin_port = bb_lookup_port(argv[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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cfd = sfd;
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}
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}
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if (wsecs) {
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alarm(0);
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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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if (cfd) {
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signal(SIGCHLD, SIG_IGN);
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dup2(cfd, 0);
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close(cfd);
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}
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dup2(0, 1);
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dup2(0, 2);
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// With more than one -l, repeatedly act as server.
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if (do_listen > 1 && vfork()) {
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// This is a bit weird as cleanup goes, since we wind up with no
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// stdin/stdout/stderr. But it's small and shouldn't hurt anything.
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// We check for cfd == 0 above.
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logmode = LOGMODE_NONE;
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close(0);
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close(1);
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close(2);
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goto repeatyness;
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}
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USE_NC_EXTRA(execvp(execparam[0], execparam);)
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/* Don't print stuff or it will go over the wire.... */
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_exit(127);
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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(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++) {
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if (FD_ISSET(fd, &testfds)) {
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nread = safe_read(fd, bb_common_bufsiz1,
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sizeof(bb_common_bufsiz1));
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if (fd == cfd) {
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if (nread<1) exit(0);
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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, but
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// 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, bb_common_bufsiz1, nread);
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if (delay > 0) sleep(delay);
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}
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}
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}
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}
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