userapps/opensource/busybox/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
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <unistd.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 #define GAPING_SECURITY_HOLE
  44
  45 int nc_main(int argc, char **argv)
  46 {
  47         int do_listen = 0, lport = 0, delay = 0, tmpfd, opt, sfd, x;
  48         char buf[BUFSIZ];
  49 #ifdef GAPING_SECURITY_HOLE
  50         char * pr00gie = NULL;
  51 #endif
  52
  53         struct sockaddr_in address;
  54         struct hostent *hostinfo;
  55
  56         fd_set readfds, testfds;
  57
  58         while ((opt = getopt(argc, argv, "lp:i:e:")) > 0) {
  59                 switch (opt) {
  60                         case 'l':
  61                                 do_listen++;
  62                                 break;
  63                         case 'p':
  64                                 lport = bb_lookup_port(optarg, "tcp", 0);
  65                                 break;
  66                         case 'i':
  67                                 delay = atoi(optarg);
  68                                 break;
  69 #ifdef GAPING_SECURITY_HOLE
  70                         case 'e':
  71                                 pr00gie = optarg;
  72                                 break;
  73 #endif
  74                         default:
  75                                 bb_show_usage();
  76                 }
  77         }
  78
  79 #ifdef GAPING_SECURITY_HOLE
  80         if (pr00gie) {
  81                 /* won't need stdin */
  82                 close (STDIN_FILENO);
  83         }
  84 #endif /* GAPING_SECURITY_HOLE */
  85
  86
  87         if ((do_listen && optind != argc) || (!do_listen && optind + 2 != argc))
  88                 bb_show_usage();
  89
  90         if ((sfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
  91                 bb_perror_msg_and_die("socket");
  92         x = 1;
  93         if (setsockopt (sfd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof (x)) == -1)
  94                 bb_perror_msg_and_die ("reuseaddr failed");
  95         address.sin_family = AF_INET;
  96
  97         if (lport != 0) {
  98                 memset(&address.sin_addr, 0, sizeof(address.sin_addr));
  99                 address.sin_port = lport;
 100
 101                 if (bind(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
 102                         bb_perror_msg_and_die("bind");
 103         }
 104
 105         if (do_listen) {
 106                 socklen_t addrlen = sizeof(address);
 107
 108                 if (listen(sfd, 1) < 0)
 109                         bb_perror_msg_and_die("listen");
 110
 111                 if ((tmpfd = accept(sfd, (struct sockaddr *) &address, &addrlen)) < 0)
 112                         bb_perror_msg_and_die("accept");
 113
 114                 close(sfd);
 115                 sfd = tmpfd;
 116         } else {
 117                 hostinfo = xgethostbyname(argv[optind]);
 118
 119                 address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
 120                 address.sin_port = bb_lookup_port(argv[optind+1], "tcp", 0);
 121
 122                 if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
 123                         bb_perror_msg_and_die("connect");
 124         }
 125
 126 #ifdef GAPING_SECURITY_HOLE
 127         /* -e given? */
 128         if (pr00gie) {
 129                 dup2(sfd, 0);
 130                 close(sfd);
 131                 dup2 (0, 1);
 132                 dup2 (0, 2);
 133                 execl (pr00gie, pr00gie, NULL);
 134                 /* Don't print stuff or it will go over the wire.... */
 135                 _exit(-1);
 136         }
 137 #endif /* GAPING_SECURITY_HOLE */
 138
 139
 140         FD_ZERO(&readfds);
 141         FD_SET(sfd, &readfds);
 142         FD_SET(STDIN_FILENO, &readfds);
 143
 144         while (1) {
 145                 int fd;
 146                 int ofd;
 147                 int nread;
 148
 149                 testfds = readfds;
 150
 151                 if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
 152                         bb_perror_msg_and_die("select");
 153
 154                 for (fd = 0; fd < FD_SETSIZE; fd++) {
 155                         if (FD_ISSET(fd, &testfds)) {
 156                                 if ((nread = safe_read(fd, buf, sizeof(buf))) < 0)
 157                                         bb_perror_msg_and_die("read");
 158
 159                                 if (fd == sfd) {
 160                                         if (nread == 0)
 161                                                 exit(0);
 162                                         ofd = STDOUT_FILENO;
 163                                 } else {
 164                                         if (nread == 0)
 165                                                 shutdown(sfd, 1);
 166                                         ofd = sfd;
 167                                 }
 168
 169                                 if (bb_full_write(ofd, buf, nread) < 0)
 170                                         bb_perror_msg_and_die("write");
 171                                 if (delay > 0) {
 172                                         sleep(delay);
 173                                 }
 174                         }
 175                 }
 176         }
 177 }