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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
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 -f FILE)"
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.
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"
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_SERVER(
64//usage: "\n -l Listen mode, for inbound connects"
65//usage: IF_NC_EXTRA(
66//usage: "\n (use -ll with -e for persistent server)"
67//usage: )
68//usage: "\n -p PORT Local port"
69//usage: )
70//usage: IF_NC_EXTRA(
71//usage: "\n -w SEC Connect timeout"
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: "\n -e PROG Run PROG after connect"
75//usage: )
76//usage:
77//usage:#define nc_notes_usage ""
78//usage: IF_NC_EXTRA(
79//usage: "To use netcat as a terminal emulator on a serial port:\n\n"
80//usage: "$ stty 115200 -F /dev/ttyS0\n"
81//usage: "$ stty raw -echo -ctlecho && nc -f /dev/ttyS0\n"
82//usage: )
83//usage:
84//usage:#define nc_example_usage
85//usage: "$ nc foobar.somedomain.com 25\n"
86//usage: "220 foobar ESMTP Exim 3.12 #1 Sat, 15 Apr 2000 00:03:02 -0600\n"
87//usage: "help\n"
88//usage: "214-Commands supported:\n"
89//usage: "214- HELO EHLO MAIL RCPT DATA AUTH\n"
90//usage: "214 NOOP QUIT RSET HELP\n"
91//usage: "quit\n"
92//usage: "221 foobar closing connection\n"
93//usage:
94//usage:#endif
95
96/* Lots of small differences in features
97 * when compared to "standard" nc
98 */
99
100static void timeout(int signum UNUSED_PARAM)
101{
102 bb_error_msg_and_die("timed out");
103}
104
105int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
106int nc_main(int argc, char **argv)
107{
108 /* sfd sits _here_ only because of "repeat" option (-l -l). */
109 int sfd = 0;
110 int cfd = 0;
111 unsigned lport = 0;
112 IF_NOT_NC_SERVER(const) unsigned do_listen = 0;
113 IF_NOT_NC_EXTRA (const) unsigned wsecs = 0;
114 IF_NOT_NC_EXTRA (const) unsigned delay = 0;
115 IF_NOT_NC_EXTRA (const int execparam = 0;)
116 IF_NC_EXTRA (char **execparam = NULL;)
117 fd_set readfds, testfds;
118 int opt; /* must be signed (getopt returns -1) */
119
120 if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
121 /* getopt32 is _almost_ usable:
122 ** it cannot handle "... -e PROG -prog-opt" */
123 while ((opt = getopt(argc, argv,
124 "" IF_NC_SERVER("lp:") IF_NC_EXTRA("w:i:f:e:") )) > 0
125 ) {
126 if (ENABLE_NC_SERVER && opt == 'l')
127 IF_NC_SERVER(do_listen++);
128 else if (ENABLE_NC_SERVER && opt == 'p')
129 IF_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
130 else if (ENABLE_NC_EXTRA && opt == 'w')
131 IF_NC_EXTRA( wsecs = xatou(optarg));
132 else if (ENABLE_NC_EXTRA && opt == 'i')
133 IF_NC_EXTRA( delay = xatou(optarg));
134 else if (ENABLE_NC_EXTRA && opt == 'f')
135 IF_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
136 else if (ENABLE_NC_EXTRA && opt == 'e' && optind <= argc) {
137 /* We cannot just 'break'. We should let getopt finish.
138 ** Or else we won't be able to find where
139 ** 'host' and 'port' params are
140 ** (think "nc -w 60 host port -e PROG"). */
141 IF_NC_EXTRA(
142 char **p;
143 // +2: one for progname (optarg) and one for NULL
144 execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
145 p = execparam;
146 *p++ = optarg;
147 while (optind < argc) {
148 *p++ = argv[optind++];
149 }
150 )
151 /* optind points to argv[argc] (NULL) now.
152 ** FIXME: we assume that getopt will not count options
153 ** possibly present on "-e PROG ARGS" and will not
154 ** include them into final value of optind
155 ** which is to be used ... */
156 } else bb_show_usage();
157 }
158 argv += optind; /* ... here! */
159 argc -= optind;
160 // -l and -f don't mix
161 if (do_listen && cfd) bb_show_usage();
162 // File mode needs need zero arguments, listen mode needs zero or one,
163 // client mode needs one or two
164 if (cfd) {
165 if (argc) bb_show_usage();
166 } else if (do_listen) {
167 if (argc > 1) bb_show_usage();
168 } else {
169 if (!argc || argc > 2) bb_show_usage();
170 }
171 } else {
172 if (argc != 3) bb_show_usage();
173 argc--;
174 argv++;
175 }
176
177 if (wsecs) {
178 signal(SIGALRM, timeout);
179 alarm(wsecs);
180 }
181
182 if (!cfd) {
183 if (do_listen) {
184 sfd = create_and_bind_stream_or_die(argv[0], lport);
185 xlisten(sfd, do_listen); /* can be > 1 */
186#if 0 /* nc-1.10 does not do this (without -v) */
187 /* If we didn't specify a port number,
188 * query and print it after listen() */
189 if (!lport) {
190 len_and_sockaddr lsa;
191 lsa.len = LSA_SIZEOF_SA;
192 getsockname(sfd, &lsa.u.sa, &lsa.len);
193 lport = get_nport(&lsa.u.sa);
194 fdprintf(2, "%d\n", ntohs(lport));
195 }
196#endif
197 close_on_exec_on(sfd);
198 accept_again:
199 cfd = accept(sfd, NULL, 0);
200 if (cfd < 0)
201 bb_perror_msg_and_die("accept");
202 if (!execparam)
203 close(sfd);
204 } else {
205 cfd = create_and_connect_stream_or_die(argv[0],
206 argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0);
207 }
208 }
209
210 if (wsecs) {
211 alarm(0);
212 /* Non-ignored signals revert to SIG_DFL on exec anyway */
213 /*signal(SIGALRM, SIG_DFL);*/
214 }
215
216 /* -e given? */
217 if (execparam) {
218 pid_t pid;
219 /* With more than one -l, repeatedly act as server */
220 if (do_listen > 1 && (pid = xvfork()) != 0) {
221 /* parent */
222 /* prevent zombies */
223 signal(SIGCHLD, SIG_IGN);
224 close(cfd);
225 goto accept_again;
226 }
227 /* child, or main thread if only one -l */
228 xmove_fd(cfd, 0);
229 xdup2(0, 1);
230 /*xdup2(0, 2); - original nc 1.10 does this, we don't */
231 IF_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
232 IF_NC_EXTRA(bb_perror_msg_and_die("can't execute '%s'", execparam[0]);)
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, SHUT_WR);
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
generated by cgit at 2024-05-15 16:04:13 (GMT)