summaryrefslogtreecommitdiff
path: root/networking/nc.c (plain)
blob: 50302d8baf8fd6af0bc64e2b3f3b2da8d1da6373
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 source tree.
8 */
9//config:config NC
10//config: bool "nc"
11//config: default y
12//config: help
13//config: A simple Unix utility which reads and writes data across network
14//config: connections.
15//config:
16//config:config NC_SERVER
17//config: bool "Netcat server options (-l)"
18//config: default y
19//config: depends on NC
20//config: help
21//config: Allow netcat to act as a server.
22//config:
23//config:config NC_EXTRA
24//config: bool "Netcat extensions (-eiw and -f FILE)"
25//config: default y
26//config: depends on NC
27//config: help
28//config: Add -e (support for executing the rest of the command line after
29//config: making or receiving a successful connection), -i (delay interval for
30//config: lines sent), -w (timeout for initial connection).
31//config:
32//config:config NC_110_COMPAT
33//config: bool "Netcat 1.10 compatibility (+2.5k)"
34//config: default n # off specially for Rob
35//config: depends on NC
36//config: help
37//config: This option makes nc closely follow original nc-1.10.
38//config: The code is about 2.5k bigger. It enables
39//config: -s ADDR, -n, -u, -v, -o FILE, -z options, but loses
40//config: busybox-specific extensions: -f FILE.
41
42//applet:IF_NC(APPLET(nc, BB_DIR_USR_BIN, BB_SUID_DROP))
43
44//kbuild:lib-$(CONFIG_NC) += nc.o
45
46#include "libbb.h"
47#include "common_bufsiz.h"
48#if ENABLE_NC_110_COMPAT
49# include "nc_bloaty.c"
50#else
51
52//usage:#if !ENABLE_NC_110_COMPAT
53//usage:
54//usage:#if ENABLE_NC_SERVER || ENABLE_NC_EXTRA
55//usage:#define NC_OPTIONS_STR "\n"
56//usage:#else
57//usage:#define NC_OPTIONS_STR
58//usage:#endif
59//usage:
60//usage:#define nc_trivial_usage
61//usage: IF_NC_EXTRA("[-iN] [-wN] ")IF_NC_SERVER("[-l] [-p PORT] ")
62//usage: "["IF_NC_EXTRA("-f FILE|")"IPADDR PORT]"IF_NC_EXTRA(" [-e PROG]")
63//usage:#define nc_full_usage "\n\n"
64//usage: "Open a pipe to IP:PORT" IF_NC_EXTRA(" or FILE")
65//usage: NC_OPTIONS_STR
66//usage: IF_NC_SERVER(
67//usage: "\n -l Listen mode, for inbound connects"
68//usage: IF_NC_EXTRA(
69//usage: "\n (use -ll with -e for persistent server)"
70//usage: )
71//usage: "\n -p PORT Local port"
72//usage: )
73//usage: IF_NC_EXTRA(
74//usage: "\n -w SEC Connect timeout"
75//usage: "\n -i SEC Delay interval for lines sent"
76//usage: "\n -f FILE Use file (ala /dev/ttyS0) instead of network"
77//usage: "\n -e PROG Run PROG after connect"
78//usage: )
79//usage:
80//usage:#define nc_notes_usage ""
81//usage: IF_NC_EXTRA(
82//usage: "To use netcat as a terminal emulator on a serial port:\n\n"
83//usage: "$ stty 115200 -F /dev/ttyS0\n"
84//usage: "$ stty raw -echo -ctlecho && nc -f /dev/ttyS0\n"
85//usage: )
86//usage:
87//usage:#define nc_example_usage
88//usage: "$ nc foobar.somedomain.com 25\n"
89//usage: "220 foobar ESMTP Exim 3.12 #1 Sat, 15 Apr 2000 00:03:02 -0600\n"
90//usage: "help\n"
91//usage: "214-Commands supported:\n"
92//usage: "214- HELO EHLO MAIL RCPT DATA AUTH\n"
93//usage: "214 NOOP QUIT RSET HELP\n"
94//usage: "quit\n"
95//usage: "221 foobar closing connection\n"
96//usage:
97//usage:#endif
98
99/* Lots of small differences in features
100 * when compared to "standard" nc
101 */
102
103static void timeout(int signum UNUSED_PARAM)
104{
105 bb_error_msg_and_die("timed out");
106}
107
108int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
109int nc_main(int argc, char **argv)
110{
111 /* sfd sits _here_ only because of "repeat" option (-l -l). */
112 int sfd = 0;
113 int cfd = 0;
114 unsigned lport = 0;
115 IF_NOT_NC_SERVER(const) unsigned do_listen = 0;
116 IF_NOT_NC_EXTRA (const) unsigned wsecs = 0;
117 IF_NOT_NC_EXTRA (const) unsigned delay = 0;
118 IF_NOT_NC_EXTRA (const int execparam = 0;)
119 IF_NC_EXTRA (char **execparam = NULL;)
120 fd_set readfds, testfds;
121 int opt; /* must be signed (getopt returns -1) */
122
123 if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
124 /* getopt32 is _almost_ usable:
125 ** it cannot handle "... -e PROG -prog-opt" */
126 while ((opt = getopt(argc, argv,
127 "" IF_NC_SERVER("lp:") IF_NC_EXTRA("w:i:f:e:") )) > 0
128 ) {
129 if (ENABLE_NC_SERVER && opt == 'l')
130 IF_NC_SERVER(do_listen++);
131 else if (ENABLE_NC_SERVER && opt == 'p')
132 IF_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
133 else if (ENABLE_NC_EXTRA && opt == 'w')
134 IF_NC_EXTRA( wsecs = xatou(optarg));
135 else if (ENABLE_NC_EXTRA && opt == 'i')
136 IF_NC_EXTRA( delay = xatou(optarg));
137 else if (ENABLE_NC_EXTRA && opt == 'f')
138 IF_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
139 else if (ENABLE_NC_EXTRA && opt == 'e' && optind <= argc) {
140 /* We cannot just 'break'. We should let getopt finish.
141 ** Or else we won't be able to find where
142 ** 'host' and 'port' params are
143 ** (think "nc -w 60 host port -e PROG"). */
144 IF_NC_EXTRA(
145 char **p;
146 // +2: one for progname (optarg) and one for NULL
147 execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
148 p = execparam;
149 *p++ = optarg;
150 while (optind < argc) {
151 *p++ = argv[optind++];
152 }
153 )
154 /* optind points to argv[argc] (NULL) now.
155 ** FIXME: we assume that getopt will not count options
156 ** possibly present on "-e PROG ARGS" and will not
157 ** include them into final value of optind
158 ** which is to be used ... */
159 } else bb_show_usage();
160 }
161 argv += optind; /* ... here! */
162 argc -= optind;
163 // -l and -f don't mix
164 if (do_listen && cfd) bb_show_usage();
165 // File mode needs need zero arguments, listen mode needs zero or one,
166 // client mode needs one or two
167 if (cfd) {
168 if (argc) bb_show_usage();
169 } else if (do_listen) {
170 if (argc > 1) bb_show_usage();
171 } else {
172 if (!argc || argc > 2) bb_show_usage();
173 }
174 } else {
175 if (argc != 3) bb_show_usage();
176 argc--;
177 argv++;
178 }
179
180 if (wsecs) {
181 signal(SIGALRM, timeout);
182 alarm(wsecs);
183 }
184
185 if (!cfd) {
186 if (do_listen) {
187 sfd = create_and_bind_stream_or_die(argv[0], lport);
188 xlisten(sfd, do_listen); /* can be > 1 */
189#if 0 /* nc-1.10 does not do this (without -v) */
190 /* If we didn't specify a port number,
191 * query and print it after listen() */
192 if (!lport) {
193 len_and_sockaddr lsa;
194 lsa.len = LSA_SIZEOF_SA;
195 getsockname(sfd, &lsa.u.sa, &lsa.len);
196 lport = get_nport(&lsa.u.sa);
197 fdprintf(2, "%d\n", ntohs(lport));
198 }
199#endif
200 close_on_exec_on(sfd);
201 accept_again:
202 cfd = accept(sfd, NULL, 0);
203 if (cfd < 0)
204 bb_perror_msg_and_die("accept");
205 if (!execparam)
206 close(sfd);
207 } else {
208 cfd = create_and_connect_stream_or_die(argv[0],
209 argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0);
210 }
211 }
212
213 if (wsecs) {
214 alarm(0);
215 /* Non-ignored signals revert to SIG_DFL on exec anyway */
216 /*signal(SIGALRM, SIG_DFL);*/
217 }
218
219 /* -e given? */
220 if (execparam) {
221 pid_t pid;
222 /* With more than one -l, repeatedly act as server */
223 if (do_listen > 1 && (pid = xvfork()) != 0) {
224 /* parent */
225 /* prevent zombies */
226 signal(SIGCHLD, SIG_IGN);
227 close(cfd);
228 goto accept_again;
229 }
230 /* child, or main thread if only one -l */
231 xmove_fd(cfd, 0);
232 xdup2(0, 1);
233 /*xdup2(0, 2); - original nc 1.10 does this, we don't */
234 IF_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
235 IF_NC_EXTRA(bb_perror_msg_and_die("can't execute '%s'", execparam[0]);)
236 }
237
238 /* Select loop copying stdin to cfd, and cfd to stdout */
239
240 FD_ZERO(&readfds);
241 FD_SET(cfd, &readfds);
242 FD_SET(STDIN_FILENO, &readfds);
243
244#define iobuf bb_common_bufsiz1
245 setup_common_bufsiz();
246 for (;;) {
247 int fd;
248 int ofd;
249 int nread;
250
251 testfds = readfds;
252
253 if (select(cfd + 1, &testfds, NULL, NULL, NULL) < 0)
254 bb_perror_msg_and_die("select");
255
256 fd = STDIN_FILENO;
257 while (1) {
258 if (FD_ISSET(fd, &testfds)) {
259 nread = safe_read(fd, iobuf, COMMON_BUFSIZE);
260 if (fd == cfd) {
261 if (nread < 1)
262 exit(EXIT_SUCCESS);
263 ofd = STDOUT_FILENO;
264 } else {
265 if (nread < 1) {
266 /* Close outgoing half-connection so they get EOF,
267 * but leave incoming alone so we can see response */
268 shutdown(cfd, SHUT_WR);
269 FD_CLR(STDIN_FILENO, &readfds);
270 }
271 ofd = cfd;
272 }
273 xwrite(ofd, iobuf, nread);
274 if (delay > 0)
275 sleep(delay);
276 }
277 if (fd == cfd)
278 break;
279 fd = cfd;
280 }
281 }
282}
283#endif
284
generated by cgit at 2024-05-15 07:34:18 (GMT)