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-rw-r--r--networking/nc.c201
1 files changed, 201 insertions, 0 deletions
diff --git a/networking/nc.c b/networking/nc.c
new file mode 100644
index 000000000..5fd9242cc
--- /dev/null
+++ b/networking/nc.c
@@ -0,0 +1,201 @@
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 tarball for details.
8 */
9
10#include "busybox.h"
11
12static void timeout(int signum)
13{
14 bb_error_msg_and_die("timed out");
15}
16
17int nc_main(int argc, char **argv)
18{
19 int sfd = 0;
20 int cfd = 0;
21 SKIP_NC_SERVER(const) unsigned do_listen = 0;
22 SKIP_NC_SERVER(const) unsigned lport = 0;
23 SKIP_NC_EXTRA (const) unsigned wsecs = 0;
24 SKIP_NC_EXTRA (const) unsigned delay = 0;
25 SKIP_NC_EXTRA (const int execparam = 0;)
26 USE_NC_EXTRA (char **execparam = NULL;)
27 struct sockaddr_in address;
28 fd_set readfds, testfds;
29 int opt; /* must be signed (getopt returns -1) */
30
31 memset(&address, 0, sizeof(address));
32
33 if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
34 /* getopt32 is _almost_ usable:
35 ** it cannot handle "... -e prog -prog-opt" */
36 while ((opt = getopt(argc, argv,
37 "" USE_NC_SERVER("lp:") USE_NC_EXTRA("w:i:f:e:") )) > 0
38 ) {
39 if (ENABLE_NC_SERVER && opt=='l') USE_NC_SERVER(do_listen++);
40 else if (ENABLE_NC_SERVER && opt=='p') USE_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
41 else if (ENABLE_NC_EXTRA && opt=='w') USE_NC_EXTRA( wsecs = xatou(optarg));
42 else if (ENABLE_NC_EXTRA && opt=='i') USE_NC_EXTRA( delay = xatou(optarg));
43 else if (ENABLE_NC_EXTRA && opt=='f') USE_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
44 else if (ENABLE_NC_EXTRA && opt=='e' && optind<=argc) {
45 /* We cannot just 'break'. We should let getopt finish.
46 ** Or else we won't be able to find where
47 ** 'host' and 'port' params are
48 ** (think "nc -w 60 host port -e prog"). */
49 USE_NC_EXTRA(
50 char **p;
51 // +2: one for progname (optarg) and one for NULL
52 execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
53 p = execparam;
54 *p++ = optarg;
55 while (optind < argc) {
56 *p++ = argv[optind++];
57 }
58 )
59 /* optind points to argv[arvc] (NULL) now.
60 ** FIXME: we assume that getopt will not count options
61 ** possibly present on "-e prog args" and will not
62 ** include them into final value of optind
63 ** which is to be used ... */
64 } else bb_show_usage();
65 }
66 argv += optind; /* ... here! */
67 argc -= optind;
68 // -l and -f don't mix
69 if (do_listen && cfd) bb_show_usage();
70 // Listen or file modes need zero arguments, client mode needs 2
71 opt = ((do_listen || cfd) ? 0 : 2);
72 if (argc != opt)
73 bb_show_usage();
74 } else {
75 if (argc != 3) bb_show_usage();
76 argc--;
77 argv++;
78 }
79
80 if (wsecs) {
81 signal(SIGALRM, timeout);
82 alarm(wsecs);
83 }
84
85 if (!cfd) {
86 sfd = xsocket(AF_INET, SOCK_STREAM, 0);
87 fcntl(sfd, F_SETFD, FD_CLOEXEC);
88 setsockopt_reuseaddr(sfd);
89 address.sin_family = AF_INET;
90
91 // Set local port.
92
93 if (lport != 0) {
94 address.sin_port = lport;
95 xbind(sfd, (struct sockaddr *) &address, sizeof(address));
96 }
97
98 if (do_listen) {
99 socklen_t addrlen = sizeof(address);
100
101 xlisten(sfd, do_listen);
102
103 // If we didn't specify a port number, query and print it to stderr.
104
105 if (!lport) {
106 socklen_t len = sizeof(address);
107 getsockname(sfd, &address, &len);
108 fdprintf(2, "%d\n", SWAP_BE16(address.sin_port));
109 }
110 repeatyness:
111 cfd = accept(sfd, (struct sockaddr *) &address, &addrlen);
112 if (cfd < 0)
113 bb_perror_msg_and_die("accept");
114
115 if (!execparam) close(sfd);
116 } else {
117 struct hostent *hostinfo;
118 hostinfo = xgethostbyname(argv[0]);
119
120 address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
121 address.sin_port = bb_lookup_port(argv[1], "tcp", 0);
122
123 if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
124 bb_perror_msg_and_die("connect");
125 cfd = sfd;
126 }
127 }
128
129 if (wsecs) {
130 alarm(0);
131 signal(SIGALRM, SIG_DFL);
132 }
133
134 /* -e given? */
135 if (execparam) {
136 if (cfd) {
137 signal(SIGCHLD, SIG_IGN);
138 dup2(cfd, 0);
139 close(cfd);
140 }
141 dup2(0, 1);
142 dup2(0, 2);
143
144 // With more than one -l, repeatedly act as server.
145
146 if (do_listen > 1 && vfork()) {
147 // This is a bit weird as cleanup goes, since we wind up with no
148 // stdin/stdout/stderr. But it's small and shouldn't hurt anything.
149 // We check for cfd == 0 above.
150 logmode = LOGMODE_NONE;
151 close(0);
152 close(1);
153 close(2);
154
155 goto repeatyness;
156 }
157 USE_NC_EXTRA(execvp(execparam[0], execparam);)
158 /* Don't print stuff or it will go over the wire.... */
159 _exit(127);
160 }
161
162 // Select loop copying stdin to cfd, and cfd to stdout.
163
164 FD_ZERO(&readfds);
165 FD_SET(cfd, &readfds);
166 FD_SET(STDIN_FILENO, &readfds);
167
168 for (;;) {
169 int fd;
170 int ofd;
171 int nread;
172
173 testfds = readfds;
174
175 if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
176 bb_perror_msg_and_die("select");
177
178 for (fd = 0; fd < FD_SETSIZE; fd++) {
179 if (FD_ISSET(fd, &testfds)) {
180 nread = safe_read(fd, bb_common_bufsiz1,
181 sizeof(bb_common_bufsiz1));
182
183 if (fd == cfd) {
184 if (nread<1) exit(0);
185 ofd = STDOUT_FILENO;
186 } else {
187 if (nread<1) {
188 // Close outgoing half-connection so they get EOF, but
189 // leave incoming alone so we can see response.
190 shutdown(cfd, 1);
191 FD_CLR(STDIN_FILENO, &readfds);
192 }
193 ofd = cfd;
194 }
195
196 xwrite(ofd, bb_common_bufsiz1, nread);
197 if (delay > 0) sleep(delay);
198 }
199 }
200 }
201}
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