1 /* vi: set sw=4 ts=4: */
2 /*
3 * nc: mini-netcat - built from the ground up for LRP
4 *
5 * Copyright (C) 1998, 1999 Charles P. Wright
6 * Copyright (C) 1998 Dave Cinege
7 *
8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
9 */
10 //config:config NC
11 //config: bool "nc (11 kb)"
12 //config: default y
13 //config: help
14 //config: A simple Unix utility which reads and writes data across network
15 //config: connections.
16 //config:
17 //config:config NETCAT
18 //config: bool "netcat (11 kb)"
19 //config: default n
20 //config: help
21 //config: Alias to nc.
22 //config:
23 //config:config NC_SERVER
24 //config: bool "Netcat server options (-l)"
25 //config: default y
26 //config: depends on NC || NETCAT
27 //config: help
28 //config: Allow netcat to act as a server.
29 //config:
30 //config:config NC_EXTRA
31 //config: bool "Netcat extensions (-eiw and -f FILE)"
32 //config: default y
33 //config: depends on NC || NETCAT
34 //config: help
35 //config: Add -e (support for executing the rest of the command line after
36 //config: making or receiving a successful connection), -i (delay interval for
37 //config: lines sent), -w (timeout for initial connection).
38 //config:
39 //config:config NC_110_COMPAT
40 //config: bool "Netcat 1.10 compatibility (+2.5k)"
41 //config: default y
42 //config: depends on NC || NETCAT
43 //config: help
44 //config: This option makes nc closely follow original nc-1.10.
45 //config: The code is about 2.5k bigger. It enables
46 //config: -s ADDR, -n, -u, -v, -o FILE, -z options, but loses
47 //config: busybox-specific extensions: -f FILE.
48
49 //applet:IF_NC(APPLET(nc, BB_DIR_USR_BIN, BB_SUID_DROP))
50 // APPLET_ODDNAME:name main location suid_type help
51 //applet:IF_NETCAT(APPLET_ODDNAME(netcat, nc, BB_DIR_USR_BIN, BB_SUID_DROP, nc))
52
53 //kbuild:lib-$(CONFIG_NC) += nc.o
54 //kbuild:lib-$(CONFIG_NETCAT) += nc.o
55
56 #include "libbb.h"
57 #include "common_bufsiz.h"
58 #if ENABLE_NC_110_COMPAT
59 # include "nc_bloaty.c"
60 #else
61
62 //usage:#if !ENABLE_NC_110_COMPAT
63 //usage:
64 //usage:#if ENABLE_NC_SERVER || ENABLE_NC_EXTRA
65 //usage:#define NC_OPTIONS_STR "\n"
66 //usage:#else
67 //usage:#define NC_OPTIONS_STR
68 //usage:#endif
69 //usage:
70 //usage:#define nc_trivial_usage
71 //usage: IF_NC_EXTRA("[-iN] [-wN] ")IF_NC_SERVER("[-l] [-p PORT] ")
72 //usage: "["IF_NC_EXTRA("-f FILE|")"IPADDR PORT]"IF_NC_EXTRA(" [-e PROG]")
73 //usage:#define nc_full_usage "\n\n"
74 //usage: "Open a pipe to IP:PORT" IF_NC_EXTRA(" or FILE")
75 //usage: NC_OPTIONS_STR
76 //usage: IF_NC_SERVER(
77 //usage: "\n -l Listen mode, for inbound connects"
78 //usage: IF_NC_EXTRA(
79 //usage: "\n (use -ll with -e for persistent server)"
80 //usage: )
81 //usage: "\n -p PORT Local port"
82 //usage: )
83 //usage: IF_NC_EXTRA(
84 //usage: "\n -w SEC Connect timeout"
85 //usage: "\n -i SEC Delay interval for lines sent"
86 //usage: "\n -f FILE Use file (ala /dev/ttyS0) instead of network"
87 //usage: "\n -e PROG Run PROG after connect"
88 //usage: )
89 //usage:
90 //usage:#define nc_notes_usage ""
91 //usage: IF_NC_EXTRA(
92 //usage: "To use netcat as a terminal emulator on a serial port:\n\n"
93 //usage: "$ stty 115200 -F /dev/ttyS0\n"
94 //usage: "$ stty raw -echo -ctlecho && nc -f /dev/ttyS0\n"
95 //usage: )
96 //usage:
97 //usage:#define nc_example_usage
98 //usage: "$ nc foobar.somedomain.com 25\n"
99 //usage: "220 foobar ESMTP Exim 3.12 #1 Sat, 15 Apr 2000 00:03:02 -0600\n"
100 //usage: "help\n"
101 //usage: "214-Commands supported:\n"
102 //usage: "214- HELO EHLO MAIL RCPT DATA AUTH\n"
103 //usage: "214 NOOP QUIT RSET HELP\n"
104 //usage: "quit\n"
105 //usage: "221 foobar closing connection\n"
106 //usage:
107 //usage:#endif
108
109 /* Lots of small differences in features
110 * when compared to "standard" nc
111 */
112
timeout(int signum UNUSED_PARAM)113 static void timeout(int signum UNUSED_PARAM)
114 {
115 bb_simple_error_msg_and_die("timed out");
116 }
117
118 int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
nc_main(int argc,char ** argv)119 int nc_main(int argc, char **argv)
120 {
121 /* sfd sits _here_ only because of "repeat" option (-l -l). */
122 int sfd = sfd; /* for gcc */
123 int cfd = 0;
124 unsigned lport = 0;
125 IF_NOT_NC_SERVER(const) unsigned do_listen = 0;
126 IF_NOT_NC_EXTRA (const) unsigned wsecs = 0;
127 IF_NOT_NC_EXTRA (const) unsigned delay = 0;
128 IF_NOT_NC_EXTRA (const int execparam = 0;)
129 IF_NC_EXTRA (char **execparam = NULL;)
130 struct pollfd pfds[2];
131 int opt; /* must be signed (getopt returns -1) */
132
133 if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
134 /* getopt32 is _almost_ usable:
135 ** it cannot handle "... -e PROG -prog-opt" */
136 while ((opt = getopt(argc, argv,
137 "" IF_NC_SERVER("lp:") IF_NC_EXTRA("w:i:f:e:") )) > 0
138 ) {
139 if (ENABLE_NC_SERVER && opt == 'l')
140 IF_NC_SERVER(do_listen++);
141 else if (ENABLE_NC_SERVER && opt == 'p')
142 IF_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
143 else if (ENABLE_NC_EXTRA && opt == 'w')
144 IF_NC_EXTRA( wsecs = xatou(optarg));
145 else if (ENABLE_NC_EXTRA && opt == 'i')
146 IF_NC_EXTRA( delay = xatou(optarg));
147 else if (ENABLE_NC_EXTRA && opt == 'f')
148 IF_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
149 else if (ENABLE_NC_EXTRA && opt == 'e' && optind <= argc) {
150 /* We cannot just 'break'. We should let getopt finish.
151 ** Or else we won't be able to find where
152 ** 'host' and 'port' params are
153 ** (think "nc -w 60 host port -e PROG"). */
154 IF_NC_EXTRA(
155 char **p;
156 // +2: one for progname (optarg) and one for NULL
157 execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
158 p = execparam;
159 *p++ = optarg;
160 while (optind < argc) {
161 *p++ = argv[optind++];
162 }
163 )
164 /* optind points to argv[argc] (NULL) now.
165 ** FIXME: we assume that getopt will not count options
166 ** possibly present on "-e PROG ARGS" and will not
167 ** include them into final value of optind
168 ** which is to be used ... */
169 } else bb_show_usage();
170 }
171 argv += optind; /* ... here! */
172 argc -= optind;
173 // -l and -f don't mix
174 if (do_listen && cfd) bb_show_usage();
175 // File mode needs need zero arguments, listen mode needs zero or one,
176 // client mode needs one or two
177 if (cfd) {
178 if (argc) bb_show_usage();
179 } else if (do_listen) {
180 if (argc > 1) bb_show_usage();
181 } else {
182 if (!argc || argc > 2) bb_show_usage();
183 }
184 } else {
185 if (argc != 3) bb_show_usage();
186 argc--;
187 argv++;
188 }
189
190 if (wsecs) {
191 signal(SIGALRM, timeout);
192 alarm(wsecs);
193 }
194
195 if (!cfd) {
196 if (do_listen) {
197 sfd = create_and_bind_stream_or_die(argv[0], lport);
198 xlisten(sfd, do_listen); /* can be > 1 */
199 #if 0 /* nc-1.10 does not do this (without -v) */
200 /* If we didn't specify a port number,
201 * query and print it after listen() */
202 if (!lport) {
203 len_and_sockaddr lsa;
204 lsa.len = LSA_SIZEOF_SA;
205 getsockname(sfd, &lsa.u.sa, &lsa.len);
206 lport = get_nport(&lsa.u.sa);
207 fdprintf(2, "%d\n", ntohs(lport));
208 }
209 #endif
210 close_on_exec_on(sfd);
211 accept_again:
212 cfd = accept(sfd, NULL, 0);
213 if (cfd < 0)
214 bb_simple_perror_msg_and_die("accept");
215 if (!execparam)
216 close(sfd);
217 } else {
218 cfd = create_and_connect_stream_or_die(argv[0],
219 bb_lookup_port(argv[1], "tcp", 0));
220 }
221 }
222
223 if (wsecs) {
224 alarm(0);
225 /* Non-ignored signals revert to SIG_DFL on exec anyway */
226 /*signal(SIGALRM, SIG_DFL);*/
227 }
228
229 /* -e given? */
230 if (execparam) {
231 pid_t pid;
232 /* With more than one -l, repeatedly act as server */
233 if (do_listen > 1 && (pid = xvfork()) != 0) {
234 /* parent */
235 /* prevent zombies */
236 signal(SIGCHLD, SIG_IGN);
237 close(cfd);
238 goto accept_again;
239 }
240 /* child, or main thread if only one -l */
241 xmove_fd(cfd, 0);
242 xdup2(0, 1);
243 /*xdup2(0, 2); - original nc 1.10 does this, we don't */
244 IF_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
245 IF_NC_EXTRA(bb_perror_msg_and_die("can't execute '%s'", execparam[0]);)
246 }
247
248 /* loop copying stdin to cfd, and cfd to stdout */
249
250 pfds[0].fd = STDIN_FILENO;
251 pfds[0].events = POLLIN;
252 pfds[1].fd = cfd;
253 pfds[1].events = POLLIN;
254
255 #define iobuf bb_common_bufsiz1
256 setup_common_bufsiz();
257 for (;;) {
258 int fdidx;
259 int ofd;
260 int nread;
261
262 if (safe_poll(pfds, 2, -1) < 0)
263 bb_simple_perror_msg_and_die("poll");
264
265 fdidx = 0;
266 while (1) {
267 if (pfds[fdidx].revents) {
268 nread = safe_read(pfds[fdidx].fd, iobuf, COMMON_BUFSIZE);
269 if (fdidx != 0) {
270 if (nread < 1)
271 exit(EXIT_SUCCESS);
272 ofd = STDOUT_FILENO;
273 } else {
274 if (nread < 1) {
275 /* Close outgoing half-connection so they get EOF,
276 * but leave incoming alone so we can see response */
277 shutdown(cfd, SHUT_WR);
278 pfds[0].fd = -1;
279 }
280 ofd = cfd;
281 }
282 xwrite(ofd, iobuf, nread);
283 if (delay > 0)
284 sleep(delay);
285 }
286 if (fdidx == 1)
287 break;
288 fdidx++;
289 }
290 }
291 }
292 #endif
293