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
  52 #define buf bb_common_bufsiz1
  53
  54 #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
  55         char *pr00gie = NULL;
  56 #endif
  57
  58         struct sockaddr_in address;
  59         struct hostent *hostinfo;
  60
  61         fd_set readfds, testfds;
  62
  63         while ((opt = getopt(argc, argv, "lp:i:e:w:")) > 0) {
  64                 switch (opt) {
  65                         case 'l':
  66                                 do_listen++;
  67                                 break;
  68                         case 'p':
  69                                 lport = bb_lookup_port(optarg, "tcp", 0);
  70                                 break;
  71                         case 'i':
  72                                 delay = atoi(optarg);
  73                                 break;
  74 #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
  75                         case 'e':
  76                                 pr00gie = optarg;
  77                                 break;
  78 #endif
  79                         case 'w':
  80                                 wsecs = atoi(optarg);
  81                                 break;
  82                         default:
  83                                 bb_show_usage();
  84                 }
  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");
  95         address.sin_family = AF_INET;
  96
  97         if (wsecs) {
  98                 signal(SIGALRM, timeout);
  99                 alarm(wsecs);
 100         }
 101
 102         if (lport != 0) {
 103                 memset(&address.sin_addr, 0, sizeof(address.sin_addr));
 104                 address.sin_port = lport;
 105
 106                 if (bind(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
 107                         bb_perror_msg_and_die("bind");
 108         }
 109
 110         if (do_listen) {
 111                 socklen_t addrlen = sizeof(address);
 112
 113                 if (listen(sfd, 1) < 0)
 114                         bb_perror_msg_and_die("listen");
 115
 116                 if ((tmpfd = accept(sfd, (struct sockaddr *) &address, &addrlen)) < 0)
 117                         bb_perror_msg_and_die("accept");
 118
 119                 close(sfd);
 120                 sfd = tmpfd;
 121         } else {
 122                 hostinfo = xgethostbyname(argv[optind]);
 123
 124                 address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
 125                 address.sin_port = bb_lookup_port(argv[optind+1], "tcp", 0);
 126
 127                 if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
 128                         bb_perror_msg_and_die("connect");
 129         }
 130
 131         if (wsecs) {
 132                 alarm(0);
 133                 signal(SIGALRM, SIG_DFL);
 134         }
 135
 136 #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
 137         /* -e given? */
 138         if (pr00gie) {
 139                 dup2(sfd, 0);
 140                 close(sfd);
 141                 dup2(0, 1);
 142                 dup2(0, 2);
 143                 execl(pr00gie, pr00gie, NULL);
 144                 /* Don't print stuff or it will go over the wire.... */
 145                 _exit(-1);
 146         }
 147 #endif /* CONFIG_NC_GAPING_SECURITY_HOLE */
 148
 149         FD_ZERO(&readfds);
 150         FD_SET(sfd, &readfds);
 151         FD_SET(STDIN_FILENO, &readfds);
 152
 153         while (1) {
 154                 int fd;
 155                 int ofd;
 156                 int nread;
 157
 158                 testfds = readfds;
 159
 160                 if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
 161                         bb_perror_msg_and_die("select");
 162
 163                 for (fd = 0; fd < FD_SETSIZE; fd++) {
 164                         if (FD_ISSET(fd, &testfds)) {
 165                                 if ((nread = safe_read(fd, buf, sizeof(buf))) < 0)
 166                                         bb_perror_msg_and_die(bb_msg_read_error);
 167
 168                                 if (fd == sfd) {
 169                                         if (nread == 0)
 170                                                 exit(0);
 171                                         ofd = STDOUT_FILENO;
 172                                 } else {
 173                                         if (nread <= 0) {
 174                                                 shutdown(sfd, 1 /* send */ );
 175                                                 close(STDIN_FILENO);
 176                                                 FD_CLR(STDIN_FILENO, &readfds);
 177                                         }
 178                                         ofd = sfd;
 179                                 }
 180
 181                                 if (bb_full_write(ofd, buf, nread) < 0)
 182                                         bb_perror_msg_and_die(bb_msg_write_error);
 183                                 if (delay > 0) {
 184                                         sleep(delay);
 185                                 }
 186                         }
 187                 }
 188         }
 189 }