networking/nc.c

   1 /* vi: set sw=4 ts=4: */
   2 /*  nc: mini-netcat - built from the ground up for LRP
   3     Copyright (C) 1998  Charles P. Wright
   4
   5     0.0.1   6K      It works.
   6     0.0.2   5K      Smaller and you can also check the exit condition if you wish.
   7     0.0.3           Uses select()
   8
   9     19980918 Busy Boxed! Dave Cinege
  10     19990512 Uses Select. Charles P. Wright
  11     19990513 Fixes stdin stupidity and uses buffers.  Charles P. Wright
  12
  13     This program is free software; you can redistribute it and/or modify
  14     it under the terms of the GNU General Public License as published by
  15     the Free Software Foundation; either version 2 of the License, or
  16     (at your option) any later version.
  17
  18     This program is distributed in the hope that it will be useful,
  19     but WITHOUT ANY WARRANTY; without even the implied warranty of
  20     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21     GNU General Public License for more details.
  22
  23     You should have received a copy of the GNU General Public License
  24     along with this program; if not, write to the Free Software
  25     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  26 */
  27
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <unistd.h>
  32 #include <signal.h>
  33
  34 #include <sys/types.h>
  35 #include <sys/socket.h>
  36 #include <netinet/in.h>
  37 #include <arpa/inet.h>
  38 #include <netdb.h>
  39 #include <sys/time.h>
  40 #include <sys/ioctl.h>
  41 #include "busybox.h"
  42
  43 static void timeout(int signum)
  44 {
  45         bb_error_msg_and_die("Timed out");
  46 }
  47
  48 int nc_main(int argc, char **argv)
  49 {
  50         int do_listen = 0, lport = 0, delay = 0, wsecs = 0, tmpfd, opt, sfd, x;
  51         char buf[BUFSIZ];
  52 #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
  53         char *pr00gie = NULL;
  54 #endif
  55
  56         struct sockaddr_in address;
  57         struct hostent *hostinfo;
  58
  59         fd_set readfds, testfds;
  60
  61         while ((opt = getopt(argc, argv, "lp:i:e:w:")) > 0) {
  62                 switch (opt) {
  63                         case 'l':
  64                                 do_listen++;
  65                                 break;
  66                         case 'p':
  67                                 lport = bb_lookup_port(optarg, "tcp", 0);
  68                                 break;
  69                         case 'i':
  70                                 delay = atoi(optarg);
  71                                 break;
  72 #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
  73                         case 'e':
  74                                 pr00gie = optarg;
  75                                 break;
  76 #endif
  77                         case 'w':
  78                                 wsecs = atoi(optarg);
  79                                 break;
  80                         default:
  81                                 bb_show_usage();
  82                 }
  83         }
  84
  85 #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
  86         if (pr00gie) {
  87                 /* won't need stdin */
  88                 close (STDIN_FILENO);
  89         }
  90 #endif /* CONFIG_NC_GAPING_SECURITY_HOLE */
  91
  92         if ((do_listen && optind != argc) || (!do_listen && optind + 2 != argc))
  93                 bb_show_usage();
  94
  95         if ((sfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
  96                 bb_perror_msg_and_die("socket");
  97         x = 1;
  98         if (setsockopt (sfd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof (x)) == -1)
  99                 bb_perror_msg_and_die ("reuseaddr failed");
 100         address.sin_family = AF_INET;
 101
 102         if (wsecs) {
 103                 signal(SIGALRM, timeout);
 104                 alarm(wsecs);
 105         }
 106
 107         if (lport != 0) {
 108                 memset(&address.sin_addr, 0, sizeof(address.sin_addr));
 109                 address.sin_port = lport;
 110
 111                 if (bind(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
 112                         bb_perror_msg_and_die("bind");
 113         }
 114
 115         if (do_listen) {
 116                 socklen_t addrlen = sizeof(address);
 117
 118                 if (listen(sfd, 1) < 0)
 119                         bb_perror_msg_and_die("listen");
 120
 121                 if ((tmpfd = accept(sfd, (struct sockaddr *) &address, &addrlen)) < 0)
 122                         bb_perror_msg_and_die("accept");
 123
 124                 close(sfd);
 125                 sfd = tmpfd;
 126         } else {
 127                 hostinfo = xgethostbyname(argv[optind]);
 128
 129                 address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
 130                 address.sin_port = bb_lookup_port(argv[optind+1], "tcp", 0);
 131
 132                 if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
 133                         bb_perror_msg_and_die("connect");
 134         }
 135
 136         if (wsecs) {
 137                 alarm(0);
 138                 signal(SIGALRM, SIG_DFL);
 139         }
 140
 141 #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
 142         /* -e given? */
 143         if (pr00gie) {
 144                 dup2(sfd, 0);
 145                 close(sfd);
 146                 dup2(0, 1);
 147                 dup2(0, 2);
 148                 execl(pr00gie, pr00gie, NULL);
 149                 /* Don't print stuff or it will go over the wire.... */
 150                 _exit(-1);
 151         }
 152 #endif /* CONFIG_NC_GAPING_SECURITY_HOLE */
 153
 154         FD_ZERO(&readfds);
 155         FD_SET(sfd, &readfds);
 156         FD_SET(STDIN_FILENO, &readfds);
 157
 158         while (1) {
 159                 int fd;
 160                 int ofd;
 161                 int nread;
 162
 163                 testfds = readfds;
 164
 165                 if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
 166                         bb_perror_msg_and_die("select");
 167
 168                 for (fd = 0; fd < FD_SETSIZE; fd++) {
 169                         if (FD_ISSET(fd, &testfds)) {
 170                                 if ((nread = safe_read(fd, buf, sizeof(buf))) < 0)
 171                                         bb_perror_msg_and_die("read");
 172
 173                                 if (fd == sfd) {
 174                                         if (nread == 0)
 175                                                 exit(0);
 176                                         ofd = STDOUT_FILENO;
 177                                 } else {
 178                                         if (nread == 0)
 179                                                 shutdown(sfd, 1);
 180                                         ofd = sfd;
 181                                 }
 182
 183                                 if (bb_full_write(ofd, buf, nread) < 0)
 184                                         bb_perror_msg_and_die("write");
 185                                 if (delay > 0) {
 186                                         sleep(delay);
 187                                 }
 188                         }
 189                 }
 190         }
 191 }