1/* vi: set sw=4 ts=4: */ 2/* nc: mini-netcat - built from the ground up for LRP 3 * 4 * Copyright (C) 1998, 1999 Charles P. Wright 5 * Copyright (C) 1998 Dave Cinege 6 * 7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. 8 */ 9 10#include "libbb.h" 11 12//config:config NC 13//config: bool "nc" 14//config: default y 15//config: help 16//config: A simple Unix utility which reads and writes data across network 17//config: connections. 18//config: 19//config:config NC_SERVER 20//config: bool "Netcat server options (-l)" 21//config: default y 22//config: depends on NC 23//config: help 24//config: Allow netcat to act as a server. 25//config: 26//config:config NC_EXTRA 27//config: bool "Netcat extensions (-eiw and filename)" 28//config: default y 29//config: depends on NC 30//config: help 31//config: Add -e (support for executing the rest of the command line after 32//config: making or receiving a successful connection), -i (delay interval for 33//config: lines sent), -w (timeout for initial connection). 34//config: 35//config:config NC_110_COMPAT 36//config: bool "Netcat 1.10 compatibility (+2.5k)" 37//config: default n # off specially for Rob 38//config: depends on NC 39//config: help 40//config: This option makes nc closely follow original nc-1.10. 41//config: The code is about 2.5k bigger. It enables 42//config: -s ADDR, -n, -u, -v, -o FILE, -z options, but loses 43//config: busybox-specific extensions: -f FILE and -ll. 44 45#if ENABLE_NC_110_COMPAT 46# include "nc_bloaty.c" 47#else 48 49//usage:#if !ENABLE_NC_110_COMPAT 50//usage: 51//usage:#if ENABLE_NC_SERVER || ENABLE_NC_EXTRA 52//usage:#define NC_OPTIONS_STR "\n\nOptions:" 53//usage:#else 54//usage:#define NC_OPTIONS_STR 55//usage:#endif 56//usage: 57//usage:#define nc_trivial_usage 58//usage: IF_NC_EXTRA("[-iN] [-wN] ")IF_NC_SERVER("[-l] [-p PORT] ") 59//usage: "["IF_NC_EXTRA("-f FILE|")"IPADDR PORT]"IF_NC_EXTRA(" [-e PROG]") 60//usage:#define nc_full_usage "\n\n" 61//usage: "Open a pipe to IP:PORT" IF_NC_EXTRA(" or FILE") 62//usage: NC_OPTIONS_STR 63//usage: IF_NC_EXTRA( 64//usage: "\n -e PROG Run PROG after connect" 65//usage: IF_NC_SERVER( 66//usage: "\n -l Listen mode, for inbound connects" 67//usage: IF_NC_EXTRA( 68//usage: "\n (use -l twice with -e for persistent server)") 69//usage: "\n -p PORT Local port" 70//usage: ) 71//usage: "\n -w SEC Timeout for connect" 72//usage: "\n -i SEC Delay interval for lines sent" 73//usage: "\n -f FILE Use file (ala /dev/ttyS0) instead of network" 74//usage: ) 75//usage: 76//usage:#define nc_notes_usage "" 77//usage: IF_NC_EXTRA( 78//usage: "To use netcat as a terminal emulator on a serial port:\n\n" 79//usage: "$ stty 115200 -F /dev/ttyS0\n" 80//usage: "$ stty raw -echo -ctlecho && nc -f /dev/ttyS0\n" 81//usage: ) 82//usage: 83//usage:#define nc_example_usage 84//usage: "$ nc foobar.somedomain.com 25\n" 85//usage: "220 foobar ESMTP Exim 3.12 #1 Sat, 15 Apr 2000 00:03:02 -0600\n" 86//usage: "help\n" 87//usage: "214-Commands supported:\n" 88//usage: "214- HELO EHLO MAIL RCPT DATA AUTH\n" 89//usage: "214 NOOP QUIT RSET HELP\n" 90//usage: "quit\n" 91//usage: "221 foobar closing connection\n" 92//usage: 93//usage:#endif 94 95/* Lots of small differences in features 96 * when compared to "standard" nc 97 */ 98 99static void timeout(int signum UNUSED_PARAM) 100{ 101 bb_error_msg_and_die("timed out"); 102} 103 104int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; 105int nc_main(int argc, char **argv) 106{ 107 /* sfd sits _here_ only because of "repeat" option (-l -l). */ 108 int sfd = sfd; /* for gcc */ 109 int cfd = 0; 110 unsigned lport = 0; 111 IF_NOT_NC_SERVER(const) unsigned do_listen = 0; 112 IF_NOT_NC_EXTRA (const) unsigned wsecs = 0; 113 IF_NOT_NC_EXTRA (const) unsigned delay = 0; 114 IF_NOT_NC_EXTRA (const int execparam = 0;) 115 IF_NC_EXTRA (char **execparam = NULL;) 116 fd_set readfds, testfds; 117 int opt; /* must be signed (getopt returns -1) */ 118 119 if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) { 120 /* getopt32 is _almost_ usable: 121 ** it cannot handle "... -e PROG -prog-opt" */ 122 while ((opt = getopt(argc, argv, 123 "" IF_NC_SERVER("lp:") IF_NC_EXTRA("w:i:f:e:") )) > 0 124 ) { 125 if (ENABLE_NC_SERVER && opt == 'l') 126 IF_NC_SERVER(do_listen++); 127 else if (ENABLE_NC_SERVER && opt == 'p') 128 IF_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0)); 129 else if (ENABLE_NC_EXTRA && opt == 'w') 130 IF_NC_EXTRA( wsecs = xatou(optarg)); 131 else if (ENABLE_NC_EXTRA && opt == 'i') 132 IF_NC_EXTRA( delay = xatou(optarg)); 133 else if (ENABLE_NC_EXTRA && opt == 'f') 134 IF_NC_EXTRA( cfd = xopen(optarg, O_RDWR)); 135 else if (ENABLE_NC_EXTRA && opt == 'e' && optind <= argc) { 136 /* We cannot just 'break'. We should let getopt finish. 137 ** Or else we won't be able to find where 138 ** 'host' and 'port' params are 139 ** (think "nc -w 60 host port -e PROG"). */ 140 IF_NC_EXTRA( 141 char **p; 142 // +2: one for progname (optarg) and one for NULL 143 execparam = xzalloc(sizeof(char*) * (argc - optind + 2)); 144 p = execparam; 145 *p++ = optarg; 146 while (optind < argc) { 147 *p++ = argv[optind++]; 148 } 149 ) 150 /* optind points to argv[arvc] (NULL) now. 151 ** FIXME: we assume that getopt will not count options 152 ** possibly present on "-e PROG ARGS" and will not 153 ** include them into final value of optind 154 ** which is to be used ... */ 155 } else bb_show_usage(); 156 } 157 argv += optind; /* ... here! */ 158 argc -= optind; 159 // -l and -f don't mix 160 if (do_listen && cfd) bb_show_usage(); 161 // File mode needs need zero arguments, listen mode needs zero or one, 162 // client mode needs one or two 163 if (cfd) { 164 if (argc) bb_show_usage(); 165 } else if (do_listen) { 166 if (argc > 1) bb_show_usage(); 167 } else { 168 if (!argc || argc > 2) bb_show_usage(); 169 } 170 } else { 171 if (argc != 3) bb_show_usage(); 172 argc--; 173 argv++; 174 } 175 176 if (wsecs) { 177 signal(SIGALRM, timeout); 178 alarm(wsecs); 179 } 180 181 if (!cfd) { 182 if (do_listen) { 183 sfd = create_and_bind_stream_or_die(argv[0], lport); 184 xlisten(sfd, do_listen); /* can be > 1 */ 185#if 0 /* nc-1.10 does not do this (without -v) */ 186 /* If we didn't specify a port number, 187 * query and print it after listen() */ 188 if (!lport) { 189 len_and_sockaddr lsa; 190 lsa.len = LSA_SIZEOF_SA; 191 getsockname(sfd, &lsa.u.sa, &lsa.len); 192 lport = get_nport(&lsa.u.sa); 193 fdprintf(2, "%d\n", ntohs(lport)); 194 } 195#endif 196 close_on_exec_on(sfd); 197 accept_again: 198 cfd = accept(sfd, NULL, 0); 199 if (cfd < 0) 200 bb_perror_msg_and_die("accept"); 201 if (!execparam) 202 close(sfd); 203 } else { 204 cfd = create_and_connect_stream_or_die(argv[0], 205 argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0); 206 } 207 } 208 209 if (wsecs) { 210 alarm(0); 211 /* Non-ignored signals revert to SIG_DFL on exec anyway */ 212 /*signal(SIGALRM, SIG_DFL);*/ 213 } 214 215 /* -e given? */ 216 if (execparam) { 217 pid_t pid; 218 /* With more than one -l, repeatedly act as server */ 219 if (do_listen > 1 && (pid = xvfork()) != 0) { 220 /* parent */ 221 /* prevent zombies */ 222 signal(SIGCHLD, SIG_IGN); 223 close(cfd); 224 goto accept_again; 225 } 226 /* child, or main thread if only one -l */ 227 xmove_fd(cfd, 0); 228 xdup2(0, 1); 229 xdup2(0, 2); 230 IF_NC_EXTRA(BB_EXECVP(execparam[0], execparam);) 231 /* Don't print stuff or it will go over the wire... */ 232 _exit(127); 233 } 234 235 /* Select loop copying stdin to cfd, and cfd to stdout */ 236 237 FD_ZERO(&readfds); 238 FD_SET(cfd, &readfds); 239 FD_SET(STDIN_FILENO, &readfds); 240 241 for (;;) { 242 int fd; 243 int ofd; 244 int nread; 245 246 testfds = readfds; 247 248 if (select(cfd + 1, &testfds, NULL, NULL, NULL) < 0) 249 bb_perror_msg_and_die("select"); 250 251#define iobuf bb_common_bufsiz1 252 fd = STDIN_FILENO; 253 while (1) { 254 if (FD_ISSET(fd, &testfds)) { 255 nread = safe_read(fd, iobuf, sizeof(iobuf)); 256 if (fd == cfd) { 257 if (nread < 1) 258 exit(EXIT_SUCCESS); 259 ofd = STDOUT_FILENO; 260 } else { 261 if (nread < 1) { 262 /* Close outgoing half-connection so they get EOF, 263 * but leave incoming alone so we can see response */ 264 shutdown(cfd, 1); 265 FD_CLR(STDIN_FILENO, &readfds); 266 } 267 ofd = cfd; 268 } 269 xwrite(ofd, iobuf, nread); 270 if (delay > 0) 271 sleep(delay); 272 } 273 if (fd == cfd) 274 break; 275 fd = cfd; 276 } 277 } 278} 279#endif 280