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 "libbb.h"
11
12#if ENABLE_DESKTOP
13#include "nc_bloaty.c"
14#else
15
16/* Lots of small differences in features
17 * when compared to "standard" nc
18 */
19
20static void timeout(int signum)
21{
22	bb_error_msg_and_die("timed out");
23}
24
25int nc_main(int argc, char **argv);
26int nc_main(int argc, char **argv)
27{
28	/* sfd sits _here_ only because of "repeat" option (-l -l). */
29	int sfd = sfd; /* for gcc */
30	int cfd = 0;
31	unsigned lport = 0;
32	SKIP_NC_SERVER(const) unsigned do_listen = 0;
33	SKIP_NC_EXTRA (const) unsigned wsecs = 0;
34	SKIP_NC_EXTRA (const) unsigned delay = 0;
35	SKIP_NC_EXTRA (const int execparam = 0;)
36	USE_NC_EXTRA  (char **execparam = NULL;)
37	len_and_sockaddr *lsa;
38	fd_set readfds, testfds;
39	int opt; /* must be signed (getopt returns -1) */
40
41	if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
42		/* getopt32 is _almost_ usable:
43		** it cannot handle "... -e prog -prog-opt" */
44		while ((opt = getopt(argc, argv,
45		        "" USE_NC_SERVER("lp:") USE_NC_EXTRA("w:i:f:e:") )) > 0
46		) {
47			if (ENABLE_NC_SERVER && opt=='l')      USE_NC_SERVER(do_listen++);
48			else if (ENABLE_NC_SERVER && opt=='p') {
49				USE_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
50			}
51			else if (ENABLE_NC_EXTRA && opt=='w') USE_NC_EXTRA( wsecs = xatou(optarg));
52			else if (ENABLE_NC_EXTRA && opt=='i') USE_NC_EXTRA( delay = xatou(optarg));
53			else if (ENABLE_NC_EXTRA && opt=='f') USE_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
54			else if (ENABLE_NC_EXTRA && opt=='e' && optind<=argc) {
55				/* We cannot just 'break'. We should let getopt finish.
56				** Or else we won't be able to find where
57				** 'host' and 'port' params are
58				** (think "nc -w 60 host port -e prog"). */
59				USE_NC_EXTRA(
60					char **p;
61					// +2: one for progname (optarg) and one for NULL
62					execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
63					p = execparam;
64					*p++ = optarg;
65					while (optind < argc) {
66						*p++ = argv[optind++];
67					}
68				)
69			} else bb_show_usage();
70		}
71		argv += optind; /* ... here! */
72		argc -= optind;
73		// -l and -f don't mix
74		if (do_listen && cfd) bb_show_usage();
75		// Listen or file modes need zero arguments, client mode needs 2
76		if (do_listen || cfd) {
77			if (argc) bb_show_usage();
78		} else {
79			if (!argc || argc > 2) bb_show_usage();
80		}
81	} else {
82		if (argc != 3) bb_show_usage();
83		argc--;
84		argv++;
85	}
86
87	if (wsecs) {
88		signal(SIGALRM, timeout);
89		alarm(wsecs);
90	}
91
92	if (!cfd) {
93		if (do_listen) {
94			/* create_and_bind_stream_or_die(NULL, lport)
95			 * would've work wonderfully, but we need
96			 * to know lsa */
97			sfd = xsocket_stream(&lsa);
98			if (lport)
99				set_nport(lsa, htons(lport));
100			setsockopt_reuseaddr(sfd);
101			xbind(sfd, &lsa->sa, lsa->len);
102			xlisten(sfd, do_listen); /* can be > 1 */
103			/* If we didn't specify a port number,
104			 * query and print it after listen() */
105			if (!lport) {
106				socklen_t addrlen = lsa->len;
107				getsockname(sfd, &lsa->sa, &addrlen);
108				lport = get_nport(&lsa->sa);
109				fdprintf(2, "%d\n", ntohs(lport));
110			}
111			fcntl(sfd, F_SETFD, FD_CLOEXEC);
112 accept_again:
113			cfd = accept(sfd, NULL, 0);
114			if (cfd < 0)
115				bb_perror_msg_and_die("accept");
116			if (!execparam)
117				close(sfd);
118		} else {
119			cfd = create_and_connect_stream_or_die(argv[0],
120				argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0);
121		}
122	}
123
124	if (wsecs) {
125		alarm(0);
126		signal(SIGALRM, SIG_DFL);
127	}
128
129	/* -e given? */
130	if (execparam) {
131		signal(SIGCHLD, SIG_IGN);
132		// With more than one -l, repeatedly act as server.
133		if (do_listen > 1 && vfork()) {
134			/* parent */
135			// This is a bit weird as cleanup goes, since we wind up with no
136			// stdin/stdout/stderr.  But it's small and shouldn't hurt anything.
137			// We check for cfd == 0 above.
138			logmode = LOGMODE_NONE;
139			close(0);
140			close(1);
141			close(2);
142			goto accept_again;
143		}
144		/* child (or main thread if no multiple -l) */
145		if (cfd) {
146			dup2(cfd, 0);
147			close(cfd);
148		}
149		dup2(0, 1);
150		dup2(0, 2);
151		USE_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
152		/* Don't print stuff or it will go over the wire.... */
153		_exit(127);
154	}
155
156	// Select loop copying stdin to cfd, and cfd to stdout.
157
158	FD_ZERO(&readfds);
159	FD_SET(cfd, &readfds);
160	FD_SET(STDIN_FILENO, &readfds);
161
162	for (;;) {
163		int fd;
164		int ofd;
165		int nread;
166
167		testfds = readfds;
168
169		if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
170			bb_perror_msg_and_die("select");
171
172#define iobuf bb_common_bufsiz1
173		for (fd = 0; fd < FD_SETSIZE; fd++) {
174			if (FD_ISSET(fd, &testfds)) {
175				nread = safe_read(fd, iobuf, sizeof(iobuf));
176				if (fd == cfd) {
177					if (nread < 1)
178						exit(0);
179					ofd = STDOUT_FILENO;
180				} else {
181					if (nread<1) {
182						// Close outgoing half-connection so they get EOF, but
183						// leave incoming alone so we can see response.
184						shutdown(cfd, 1);
185						FD_CLR(STDIN_FILENO, &readfds);
186					}
187					ofd = cfd;
188				}
189				xwrite(ofd, iobuf, nread);
190				if (delay > 0) sleep(delay);
191			}
192		}
193	}
194}
195#endif
196