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
195
196
197
|
/* vi: set sw=4 ts=4: */
/* nc: mini-netcat - built from the ground up for LRP
*
* Copyright (C) 1998, 1999 Charles P. Wright
* Copyright (C) 1998 Dave Cinege
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include "busybox.h"
/* Lots of small differences in features
* when compared to "standard" nc
*/
static void timeout(int signum)
{
bb_error_msg_and_die("timed out");
}
int nc_main(int argc, char **argv);
int nc_main(int argc, char **argv)
{
/* sfd sits _here_ only because of "repeat" option (-l -l). */
int sfd = sfd; /* for gcc */
int cfd = 0;
unsigned lport = 0;
SKIP_NC_SERVER(const) unsigned do_listen = 0;
SKIP_NC_EXTRA (const) unsigned wsecs = 0;
SKIP_NC_EXTRA (const) unsigned delay = 0;
SKIP_NC_EXTRA (const int execparam = 0;)
USE_NC_EXTRA (char **execparam = NULL;)
len_and_sockaddr *lsa;
fd_set readfds, testfds;
int opt; /* must be signed (getopt returns -1) */
if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
/* getopt32 is _almost_ usable:
** it cannot handle "... -e prog -prog-opt" */
while ((opt = getopt(argc, argv,
"" USE_NC_SERVER("lp:") USE_NC_EXTRA("w:i:f:e:") )) > 0
) {
if (ENABLE_NC_SERVER && opt=='l') USE_NC_SERVER(do_listen++);
else if (ENABLE_NC_SERVER && opt=='p') {
USE_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
}
else if (ENABLE_NC_EXTRA && opt=='w') USE_NC_EXTRA( wsecs = xatou(optarg));
else if (ENABLE_NC_EXTRA && opt=='i') USE_NC_EXTRA( delay = xatou(optarg));
else if (ENABLE_NC_EXTRA && opt=='f') USE_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
else if (ENABLE_NC_EXTRA && opt=='e' && optind<=argc) {
/* We cannot just 'break'. We should let getopt finish.
** Or else we won't be able to find where
** 'host' and 'port' params are
** (think "nc -w 60 host port -e prog"). */
USE_NC_EXTRA(
char **p;
// +2: one for progname (optarg) and one for NULL
execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
p = execparam;
*p++ = optarg;
while (optind < argc) {
*p++ = argv[optind++];
}
)
/* optind points to argv[arvc] (NULL) now.
** FIXME: we assume that getopt will not count options
** possibly present on "-e prog args" and will not
** include them into final value of optind
** which is to be used ... */
} else bb_show_usage();
}
argv += optind; /* ... here! */
argc -= optind;
// -l and -f don't mix
if (do_listen && cfd) bb_show_usage();
// Listen or file modes need zero arguments, client mode needs 2
if (do_listen || cfd) {
if (argc) bb_show_usage();
} else {
if (!argc || argc > 2) bb_show_usage();
}
} else {
if (argc != 3) bb_show_usage();
argc--;
argv++;
}
if (wsecs) {
signal(SIGALRM, timeout);
alarm(wsecs);
}
if (!cfd) {
if (do_listen) {
/* create_and_bind_stream_or_die(NULL, lport)
* would've work wonderfully, but we need
* to know lsa */
sfd = xsocket_stream(&lsa);
if (lport)
set_nport(lsa, htons(lport));
setsockopt_reuseaddr(sfd);
xbind(sfd, &lsa->sa, lsa->len);
xlisten(sfd, do_listen); /* can be > 1 */
/* If we didn't specify a port number,
* query and print it after listen() */
if (!lport) {
socklen_t addrlen = lsa->len;
getsockname(sfd, &lsa->sa, &addrlen);
lport = get_nport(lsa);
fdprintf(2, "%d\n", ntohs(lport));
}
fcntl(sfd, F_SETFD, FD_CLOEXEC);
accept_again:
cfd = accept(sfd, NULL, 0);
if (cfd < 0)
bb_perror_msg_and_die("accept");
if (!execparam)
close(sfd);
} else {
cfd = create_and_connect_stream_or_die(argv[0],
argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0);
}
}
if (wsecs) {
alarm(0);
signal(SIGALRM, SIG_DFL);
}
/* -e given? */
if (execparam) {
signal(SIGCHLD, SIG_IGN);
// With more than one -l, repeatedly act as server.
if (do_listen > 1 && vfork()) {
/* parent */
// This is a bit weird as cleanup goes, since we wind up with no
// stdin/stdout/stderr. But it's small and shouldn't hurt anything.
// We check for cfd == 0 above.
logmode = LOGMODE_NONE;
close(0);
close(1);
close(2);
goto accept_again;
}
/* child (or main thread if no multiple -l) */
if (cfd) {
dup2(cfd, 0);
close(cfd);
}
dup2(0, 1);
dup2(0, 2);
USE_NC_EXTRA(execvp(execparam[0], execparam);)
/* Don't print stuff or it will go over the wire.... */
_exit(127);
}
// Select loop copying stdin to cfd, and cfd to stdout.
FD_ZERO(&readfds);
FD_SET(cfd, &readfds);
FD_SET(STDIN_FILENO, &readfds);
for (;;) {
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)) {
nread = safe_read(fd, bb_common_bufsiz1,
sizeof(bb_common_bufsiz1));
if (fd == cfd) {
if (nread < 1)
exit(0);
ofd = STDOUT_FILENO;
} else {
if (nread<1) {
// Close outgoing half-connection so they get EOF, but
// leave incoming alone so we can see response.
shutdown(cfd, 1);
FD_CLR(STDIN_FILENO, &readfds);
}
ofd = cfd;
}
xwrite(ofd, bb_common_bufsiz1, nread);
if (delay > 0) sleep(delay);
}
}
}
}
|
