aboutsummaryrefslogtreecommitdiff
path: root/networking/nc.c
blob: bf155b3b13bb3148dd3fc11d94c4dac2cbb1c489 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
/* vi: set sw=4 ts=4: */
/*  nc: mini-netcat - built from the ground up for LRP
    Copyright (C) 1998  Charles P. Wright

    0.0.1   6K      It works.
    0.0.2   5K      Smaller and you can also check the exit condition if you wish.
    0.0.3           Uses select()

    19980918 Busy Boxed! Dave Cinege
    19990512 Uses Select. Charles P. Wright
    19990513 Fixes stdin stupidity and uses buffers.  Charles P. Wright

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include "busybox.h"

static void timeout(int signum)
{
	bb_error_msg_and_die("Timed out");
}

int nc_main(int argc, char **argv)
{
	int do_listen = 0, lport = 0, delay = 0, wsecs = 0, tmpfd, opt, sfd, x;
	char buf[BUFSIZ];
#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
	char *pr00gie = NULL;
#endif

	struct sockaddr_in address;
	struct hostent *hostinfo;

	fd_set readfds, testfds;

	while ((opt = getopt(argc, argv, "lp:i:e:w:")) > 0) {
		switch (opt) {
			case 'l':
				do_listen++;
				break;
			case 'p':
				lport = bb_lookup_port(optarg, "tcp", 0);
				break;
			case 'i':
				delay = atoi(optarg);
				break;
#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
			case 'e':
				pr00gie = optarg;
				break;
#endif
			case 'w':
				wsecs = atoi(optarg);
				break;
			default:
				bb_show_usage();
		}
	}

#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
	if (pr00gie) {
		/* won't need stdin */
		close(STDIN_FILENO);      
	}
#endif /* CONFIG_NC_GAPING_SECURITY_HOLE */

	if ((do_listen && optind != argc) || (!do_listen && optind + 2 != argc))
		bb_show_usage();

	if ((sfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
		bb_perror_msg_and_die("socket");
	x = 1;
	if (setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof (x)) == -1)
		bb_perror_msg_and_die("reuseaddr");
	address.sin_family = AF_INET;

	if (wsecs) {
		signal(SIGALRM, timeout);
		alarm(wsecs);
	}

	if (lport != 0) {
		memset(&address.sin_addr, 0, sizeof(address.sin_addr));
		address.sin_port = lport;

		if (bind(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
			bb_perror_msg_and_die("bind");
	}

	if (do_listen) {
		socklen_t addrlen = sizeof(address);

		if (listen(sfd, 1) < 0)
			bb_perror_msg_and_die("listen");

		if ((tmpfd = accept(sfd, (struct sockaddr *) &address, &addrlen)) < 0)
			bb_perror_msg_and_die("accept");

		close(sfd);
		sfd = tmpfd;
	} else {
		hostinfo = xgethostbyname(argv[optind]);

		address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
		address.sin_port = bb_lookup_port(argv[optind+1], "tcp", 0);

		if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
			bb_perror_msg_and_die("connect");
	}

	if (wsecs) {
		alarm(0);
		signal(SIGALRM, SIG_DFL);
	}

#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
	/* -e given? */
	if (pr00gie) {
		dup2(sfd, 0);
		close(sfd);
		dup2(0, 1);
		dup2(0, 2);
		execl(pr00gie, pr00gie, NULL);
		/* Don't print stuff or it will go over the wire.... */
		_exit(-1);
	}
#endif /* CONFIG_NC_GAPING_SECURITY_HOLE */

	FD_ZERO(&readfds);
	FD_SET(sfd, &readfds);
	FD_SET(STDIN_FILENO, &readfds);

	while (1) {
		int fd;
		int ofd;
		int nread;

		testfds = readfds;

		if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
			bb_perror_msg_and_die("select");

		for (fd = 0; fd < FD_SETSIZE; fd++) {
			if (FD_ISSET(fd, &testfds)) {
				if ((nread = safe_read(fd, buf, sizeof(buf))) < 0)
					bb_perror_msg_and_die(bb_msg_read_error);

				if (fd == sfd) {
					if (nread == 0)
						exit(0);
					ofd = STDOUT_FILENO;
				} else {
					if (nread <= 0) {
						shutdown(sfd, 1 /* send */ );
						close(STDIN_FILENO);
						FD_CLR(STDIN_FILENO, &readfds);
					}
					ofd = sfd;
				}

				if (bb_full_write(ofd, buf, nread) < 0)
					bb_perror_msg_and_die(bb_msg_write_error);
				if (delay > 0) {
					sleep(delay);
				}
			}
		}
	}
}