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Denis Vlasenko29fe7262007-04-05 20:26:28 +00001/* Based on netcat 1.10 RELEASE 960320 written by hobbit@avian.org.
2 * Released into public domain by the author.
3 *
Denis Vlasenko7cff01e2008-02-02 16:23:43 +00004 * Copyright (C) 2007 Denys Vlasenko.
Denis Vlasenko29fe7262007-04-05 20:26:28 +00005 *
6 * Licensed under GPLv2, see file LICENSE in this tarball for details.
7 */
8
9/* Author's comments from nc 1.10:
10 * =====================
11 * Netcat is entirely my own creation, although plenty of other code was used as
12 * examples. It is freely given away to the Internet community in the hope that
13 * it will be useful, with no restrictions except giving credit where it is due.
14 * No GPLs, Berkeley copyrights or any of that nonsense. The author assumes NO
15 * responsibility for how anyone uses it. If netcat makes you rich somehow and
16 * you're feeling generous, mail me a check. If you are affiliated in any way
17 * with Microsoft Network, get a life. Always ski in control. Comments,
18 * questions, and patches to hobbit@avian.org.
19 * ...
20 * Netcat and the associated package is a product of Avian Research, and is freely
21 * available in full source form with no restrictions save an obligation to give
22 * credit where due.
23 * ...
24 * A damn useful little "backend" utility begun 950915 or thereabouts,
25 * as *Hobbit*'s first real stab at some sockets programming. Something that
26 * should have and indeed may have existed ten years ago, but never became a
27 * standard Unix utility. IMHO, "nc" could take its place right next to cat,
28 * cp, rm, mv, dd, ls, and all those other cryptic and Unix-like things.
29 * =====================
30 *
31 * Much of author's comments are still retained in the code.
32 *
33 * Functionality removed (rationale):
34 * - miltiple-port ranges, randomized port scanning (use nmap)
35 * - telnet support (use telnet)
36 * - source routing
37 * - multiple DNS checks
38 * Functionalty which is different from nc 1.10:
39 * - Prog in '-e prog' can have prog's parameters and options.
40 * Because of this -e option must be last.
41 * - nc doesn't redirect stderr to the network socket for the -e prog.
Denis Vlasenko19507f02007-04-06 10:41:05 +000042 * - numeric addresses are printed in (), not [] (IPv6 looks better),
43 * port numbers are inside (): (1.2.3.4:5678)
44 * - network read errors are reported on verbose levels > 1
45 * (nc 1.10 treats them as EOF)
46 * - TCP connects from wrong ip/ports (if peer ip:port is specified
47 * on the command line, but accept() says that it came from different addr)
48 * are closed, but nc doesn't exit - continues to listen/accept.
Denis Vlasenko29fe7262007-04-05 20:26:28 +000049 */
50
Denis Vlasenkob6adbf12007-05-26 19:00:18 +000051/* done in nc.c: #include "libbb.h" */
Denis Vlasenko29fe7262007-04-05 20:26:28 +000052
Denis Vlasenko19507f02007-04-06 10:41:05 +000053enum {
54 SLEAZE_PORT = 31337, /* for UDP-scan RTT trick, change if ya want */
55 BIGSIZ = 8192, /* big buffers */
56
57 netfd = 3,
58 ofd = 4,
59};
Denis Vlasenko29fe7262007-04-05 20:26:28 +000060
61struct globals {
Denis Vlasenko19507f02007-04-06 10:41:05 +000062 /* global cmd flags: */
63 unsigned o_verbose;
64 unsigned o_wait;
65#if ENABLE_NC_EXTRA
66 unsigned o_interval;
67#endif
68
69 /*int netfd;*/
70 /*int ofd;*/ /* hexdump output fd */
Denis Vlasenko29fe7262007-04-05 20:26:28 +000071#if ENABLE_LFS
72#define SENT_N_RECV_M "sent %llu, rcvd %llu\n"
73 unsigned long long wrote_out; /* total stdout bytes */
74 unsigned long long wrote_net; /* total net bytes */
75#else
Denis Vlasenko19507f02007-04-06 10:41:05 +000076#define SENT_N_RECV_M "sent %u, rcvd %u\n"
Denis Vlasenko29fe7262007-04-05 20:26:28 +000077 unsigned wrote_out; /* total stdout bytes */
78 unsigned wrote_net; /* total net bytes */
79#endif
Bernhard Reutner-Fischera985d302008-02-11 11:44:38 +000080 /* ouraddr is never NULL and goes through three states as we progress:
Denis Vlasenko29fe7262007-04-05 20:26:28 +000081 1 - local address before bind (IP/port possibly zero)
82 2 - local address after bind (port is nonzero)
83 3 - local address after connect??/recv/accept (IP and port are nonzero) */
84 struct len_and_sockaddr *ouraddr;
85 /* themaddr is NULL if no peer hostname[:port] specified on command line */
86 struct len_and_sockaddr *themaddr;
87 /* remend is set after connect/recv/accept to the actual ip:port of peer */
88 struct len_and_sockaddr remend;
89
Denis Vlasenko29fe7262007-04-05 20:26:28 +000090 jmp_buf jbuf; /* timer crud */
Denis Vlasenko29fe7262007-04-05 20:26:28 +000091
92 /* will malloc up the following globals: */
93 fd_set ding1; /* for select loop */
94 fd_set ding2;
95 char bigbuf_in[BIGSIZ]; /* data buffers */
96 char bigbuf_net[BIGSIZ];
97};
98
99#define G (*ptr_to_globals)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000100#define wrote_out (G.wrote_out )
101#define wrote_net (G.wrote_net )
102#define ouraddr (G.ouraddr )
103#define themaddr (G.themaddr )
104#define remend (G.remend )
105#define jbuf (G.jbuf )
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000106#define ding1 (G.ding1 )
107#define ding2 (G.ding2 )
108#define bigbuf_in (G.bigbuf_in )
109#define bigbuf_net (G.bigbuf_net)
110#define o_verbose (G.o_verbose )
111#define o_wait (G.o_wait )
112#if ENABLE_NC_EXTRA
113#define o_interval (G.o_interval)
114#else
115#define o_interval 0
116#endif
Denis Vlasenko574f2f42008-02-27 18:41:59 +0000117#define INIT_G() do { \
118 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
119} while (0)
120
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000121
122/* Must match getopt32 call! */
123enum {
124 OPT_h = (1 << 0),
125 OPT_n = (1 << 1),
126 OPT_p = (1 << 2),
127 OPT_s = (1 << 3),
128 OPT_u = (1 << 4),
129 OPT_v = (1 << 5),
130 OPT_w = (1 << 6),
131 OPT_l = (1 << 7) * ENABLE_NC_SERVER,
132 OPT_i = (1 << (7+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
133 OPT_o = (1 << (8+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
134 OPT_z = (1 << (9+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
135};
136
137#define o_nflag (option_mask32 & OPT_n)
138#define o_udpmode (option_mask32 & OPT_u)
Denis Vlasenko19507f02007-04-06 10:41:05 +0000139#if ENABLE_NC_SERVER
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000140#define o_listen (option_mask32 & OPT_l)
Denis Vlasenko19507f02007-04-06 10:41:05 +0000141#else
142#define o_listen 0
143#endif
144#if ENABLE_NC_EXTRA
145#define o_ofile (option_mask32 & OPT_o)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000146#define o_zero (option_mask32 & OPT_z)
147#else
Denis Vlasenko19507f02007-04-06 10:41:05 +0000148#define o_ofile 0
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000149#define o_zero 0
150#endif
151
Denis Vlasenko19507f02007-04-06 10:41:05 +0000152/* Debug: squirt whatever message and sleep a bit so we can see it go by. */
153/* Beware: writes to stdOUT... */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000154#if 0
Denis Vlasenko51742f42007-04-12 00:32:05 +0000155#define Debug(...) do { printf(__VA_ARGS__); printf("\n"); fflush(stdout); sleep(1); } while (0)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000156#else
Denis Vlasenko51742f42007-04-12 00:32:05 +0000157#define Debug(...) do { } while (0)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000158#endif
159
Denis Vlasenko51742f42007-04-12 00:32:05 +0000160#define holler_error(...) do { if (o_verbose) bb_error_msg(__VA_ARGS__); } while (0)
161#define holler_perror(...) do { if (o_verbose) bb_perror_msg(__VA_ARGS__); } while (0)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000162
163/* catch: no-brainer interrupt handler */
164static void catch(int sig)
165{
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000166 if (o_verbose > 1) /* normally we don't care */
167 fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out);
168 fprintf(stderr, "punt!\n");
Denis Vlasenko400d8bb2008-02-24 13:36:01 +0000169 kill_myself_with_sig(sig);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000170}
171
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000172/* unarm */
173static void unarm(void)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000174{
175 signal(SIGALRM, SIG_IGN);
176 alarm(0);
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000177}
178
179/* timeout and other signal handling cruft */
180static void tmtravel(int sig)
181{
182 unarm();
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000183 longjmp(jbuf, 1);
184}
185
186/* arm: set the timer. */
187static void arm(unsigned secs)
188{
189 signal(SIGALRM, tmtravel);
190 alarm(secs);
191}
192
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000193/* findline:
194 find the next newline in a buffer; return inclusive size of that "line",
195 or the entire buffer size, so the caller knows how much to then write().
196 Not distinguishing \n vs \r\n for the nonce; it just works as is... */
197static unsigned findline(char *buf, unsigned siz)
198{
199 char * p;
200 int x;
201 if (!buf) /* various sanity checks... */
202 return 0;
203 if (siz > BIGSIZ)
204 return 0;
205 x = siz;
206 for (p = buf; x > 0; x--) {
207 if (*p == '\n') {
208 x = (int) (p - buf);
209 x++; /* 'sokay if it points just past the end! */
Denis Vlasenko19507f02007-04-06 10:41:05 +0000210Debug("findline returning %d", x);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000211 return x;
212 }
213 p++;
214 } /* for */
Denis Vlasenko19507f02007-04-06 10:41:05 +0000215Debug("findline returning whole thing: %d", siz);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000216 return siz;
217} /* findline */
218
219/* doexec:
220 fiddle all the file descriptors around, and hand off to another prog. Sort
221 of like a one-off "poor man's inetd". This is the only section of code
222 that would be security-critical, which is why it's ifdefed out by default.
223 Use at your own hairy risk; if you leave shells lying around behind open
224 listening ports you deserve to lose!! */
225static int doexec(char **proggie) ATTRIBUTE_NORETURN;
226static int doexec(char **proggie)
227{
228 xmove_fd(netfd, 0);
229 dup2(0, 1);
230 /* dup2(0, 2); - do we *really* want this? NO!
231 * exec'ed prog can do it yourself, if needed */
232 execvp(proggie[0], proggie);
233 bb_perror_msg_and_die("exec");
234}
235
236/* connect_w_timeout:
237 return an fd for one of
238 an open outbound TCP connection, a UDP stub-socket thingie, or
239 an unconnected TCP or UDP socket to listen on.
240 Examines various global o_blah flags to figure out what to do.
241 lad can be NULL, then socket is not bound to any local ip[:port] */
242static int connect_w_timeout(int fd)
243{
244 int rr;
245
246 /* wrap connect inside a timer, and hit it */
247 arm(o_wait);
248 if (setjmp(jbuf) == 0) {
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000249 rr = connect(fd, &themaddr->u.sa, themaddr->len);
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000250 unarm();
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000251 } else { /* setjmp: connect failed... */
252 rr = -1;
253 errno = ETIMEDOUT; /* fake it */
254 }
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000255 return rr;
256}
257
258/* dolisten:
259 listens for
260 incoming and returns an open connection *from* someplace. If we were
261 given host/port args, any connections from elsewhere are rejected. This
262 in conjunction with local-address binding should limit things nicely... */
263static void dolisten(void)
264{
265 int rr;
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000266
267 if (!o_udpmode)
268 xlisten(netfd, 1); /* TCP: gotta listen() before we can get */
269
270 /* Various things that follow temporarily trash bigbuf_net, which might contain
271 a copy of any recvfrom()ed packet, but we'll read() another copy later. */
272
273 /* I can't believe I have to do all this to get my own goddamn bound address
274 and port number. It should just get filled in during bind() or something.
275 All this is only useful if we didn't say -p for listening, since if we
276 said -p we *know* what port we're listening on. At any rate we won't bother
277 with it all unless we wanted to see it, although listening quietly on a
278 random unknown port is probably not very useful without "netstat". */
279 if (o_verbose) {
280 char *addr;
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000281 rr = getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000282 if (rr < 0)
283 bb_perror_msg_and_die("getsockname after bind");
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000284 addr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000285 fprintf(stderr, "listening on %s ...\n", addr);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000286 free(addr);
287 }
288
289 if (o_udpmode) {
290 /* UDP is a speeeeecial case -- we have to do I/O *and* get the calling
291 party's particulars all at once, listen() and accept() don't apply.
292 At least in the BSD universe, however, recvfrom/PEEK is enough to tell
293 us something came in, and we can set things up so straight read/write
294 actually does work after all. Yow. YMMV on strange platforms! */
295
296 /* I'm not completely clear on how this works -- BSD seems to make UDP
297 just magically work in a connect()ed context, but we'll undoubtedly run
298 into systems this deal doesn't work on. For now, we apparently have to
299 issue a connect() on our just-tickled socket so we can write() back.
300 Again, why the fuck doesn't it just get filled in and taken care of?!
301 This hack is anything but optimal. Basically, if you want your listener
302 to also be able to send data back, you need this connect() line, which
303 also has the side effect that now anything from a different source or even a
304 different port on the other end won't show up and will cause ICMP errors.
305 I guess that's what they meant by "connect".
306 Let's try to remember what the "U" is *really* for, eh? */
307
308 /* If peer address is specified, connect to it */
Denis Vlasenko19507f02007-04-06 10:41:05 +0000309 remend.len = LSA_SIZEOF_SA;
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000310 if (themaddr) {
311 remend = *themaddr;
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000312 xconnect(netfd, &themaddr->u.sa, themaddr->len);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000313 }
Denis Vlasenko19507f02007-04-06 10:41:05 +0000314 /* peek first packet and remember peer addr */
315 arm(o_wait); /* might as well timeout this, too */
316 if (setjmp(jbuf) == 0) { /* do timeout for initial connect */
317 /* (*ouraddr) is prefilled with "default" address */
318 /* and here we block... */
319 rr = recv_from_to(netfd, NULL, 0, MSG_PEEK, /*was bigbuf_net, BIGSIZ*/
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000320 &remend.u.sa, &ouraddr->u.sa, ouraddr->len);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000321 if (rr < 0)
322 bb_perror_msg_and_die("recvfrom");
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000323 unarm();
Denis Vlasenko19507f02007-04-06 10:41:05 +0000324 } else
325 bb_error_msg_and_die("timeout");
Denis Vlasenko19507f02007-04-06 10:41:05 +0000326/* Now we learned *to which IP* peer has connected, and we want to anchor
327our socket on it, so that our outbound packets will have correct local IP.
328Unfortunately, bind() on already bound socket will fail now (EINVAL):
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000329 xbind(netfd, &ouraddr->u.sa, ouraddr->len);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000330Need to read the packet, save data, close this socket and
331create new one, and bind() it. TODO */
332 if (!themaddr)
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000333 xconnect(netfd, &remend.u.sa, ouraddr->len);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000334 } else {
335 /* TCP */
336 arm(o_wait); /* wrap this in a timer, too; 0 = forever */
337 if (setjmp(jbuf) == 0) {
Denis Vlasenko19507f02007-04-06 10:41:05 +0000338 again:
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000339 remend.len = LSA_SIZEOF_SA;
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000340 rr = accept(netfd, &remend.u.sa, &remend.len);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000341 if (rr < 0)
342 bb_perror_msg_and_die("accept");
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000343 if (themaddr && memcmp(&remend.u.sa, &themaddr->u.sa, remend.len) != 0) {
Denis Vlasenko19507f02007-04-06 10:41:05 +0000344 /* nc 1.10 bails out instead, and its error message
345 * is not suppressed by o_verbose */
346 if (o_verbose) {
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000347 char *remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000348 bb_error_msg("connect from wrong ip/port %s ignored", remaddr);
349 free(remaddr);
350 }
351 close(rr);
352 goto again;
353 }
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000354 unarm();
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000355 } else
356 bb_error_msg_and_die("timeout");
Denis Vlasenko19507f02007-04-06 10:41:05 +0000357 xmove_fd(rr, netfd); /* dump the old socket, here's our new one */
358 /* find out what address the connection was *to* on our end, in case we're
359 doing a listen-on-any on a multihomed machine. This allows one to
360 offer different services via different alias addresses, such as the
361 "virtual web site" hack. */
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000362 rr = getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000363 if (rr < 0)
364 bb_perror_msg_and_die("getsockname after accept");
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000365 }
Denis Vlasenko19507f02007-04-06 10:41:05 +0000366
367 if (o_verbose) {
368 char *lcladdr, *remaddr, *remhostname;
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000369
370#if ENABLE_NC_EXTRA && defined(IP_OPTIONS)
371 /* If we can, look for any IP options. Useful for testing the receiving end of
372 such things, and is a good exercise in dealing with it. We do this before
373 the connect message, to ensure that the connect msg is uniformly the LAST
374 thing to emerge after all the intervening crud. Doesn't work for UDP on
375 any machines I've tested, but feel free to surprise me. */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000376 char optbuf[40];
377 int x = sizeof(optbuf);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000378
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000379 rr = getsockopt(netfd, IPPROTO_IP, IP_OPTIONS, optbuf, &x);
380 if (rr < 0)
381 bb_perror_msg("getsockopt failed");
382 else if (x) { /* we've got options, lessee em... */
383 bin2hex(bigbuf_net, optbuf, x);
384 bigbuf_net[2*x] = '\0';
385 fprintf(stderr, "IP options: %s\n", bigbuf_net);
386 }
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000387#endif
388
389 /* now check out who it is. We don't care about mismatched DNS names here,
390 but any ADDR and PORT we specified had better fucking well match the caller.
391 Converting from addr to inet_ntoa and back again is a bit of a kludge, but
392 gethostpoop wants a string and there's much gnarlier code out there already,
393 so I don't feel bad.
394 The *real* question is why BFD sockets wasn't designed to allow listens for
395 connections *from* specific hosts/ports, instead of requiring the caller to
396 accept the connection and then reject undesireable ones by closing.
397 In other words, we need a TCP MSG_PEEK. */
398 /* bbox: removed most of it */
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000399 lcladdr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
400 remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
401 remhostname = o_nflag ? remaddr : xmalloc_sockaddr2host(&remend.u.sa);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000402 fprintf(stderr, "connect to %s from %s (%s)\n",
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000403 lcladdr, remhostname, remaddr);
404 free(lcladdr);
405 free(remaddr);
406 if (!o_nflag)
407 free(remhostname);
408 }
409}
410
411/* udptest:
412 fire a couple of packets at a UDP target port, just to see if it's really
413 there. On BSD kernels, ICMP host/port-unreachable errors get delivered to
414 our socket as ECONNREFUSED write errors. On SV kernels, we lose; we'll have
415 to collect and analyze raw ICMP ourselves a la satan's probe_udp_ports
416 backend. Guess where one could swipe the appropriate code from...
417
418 Use the time delay between writes if given, otherwise use the "tcp ping"
419 trick for getting the RTT. [I got that idea from pluvius, and warped it.]
420 Return either the original fd, or clean up and return -1. */
Denis Vlasenko19507f02007-04-06 10:41:05 +0000421#if ENABLE_NC_EXTRA
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000422static int udptest(void)
423{
424 int rr;
425
426 rr = write(netfd, bigbuf_in, 1);
427 if (rr != 1)
428 bb_perror_msg("udptest first write");
429
430 if (o_wait)
Denis Vlasenko19507f02007-04-06 10:41:05 +0000431 sleep(o_wait); // can be interrupted! while (t) nanosleep(&t)?
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000432 else {
433 /* use the tcp-ping trick: try connecting to a normally refused port, which
434 causes us to block for the time that SYN gets there and RST gets back.
435 Not completely reliable, but it *does* mostly work. */
436 /* Set a temporary connect timeout, so packet filtration doesnt cause
437 us to hang forever, and hit it */
438 o_wait = 5; /* enough that we'll notice?? */
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000439 rr = xsocket(ouraddr->u.sa.sa_family, SOCK_STREAM, 0);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000440 set_nport(themaddr, htons(SLEAZE_PORT));
441 connect_w_timeout(rr);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000442 /* don't need to restore themaddr's port, it's not used anymore */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000443 close(rr);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000444 o_wait = 0; /* restore */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000445 }
446
447 rr = write(netfd, bigbuf_in, 1);
448 return (rr != 1); /* if rr == 1, return 0 (success) */
449}
Denis Vlasenko19507f02007-04-06 10:41:05 +0000450#else
451int udptest(void);
452#endif
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000453
454/* oprint:
455 Hexdump bytes shoveled either way to a running logfile, in the format:
456 D offset - - - - --- 16 bytes --- - - - - # .... ascii .....
457 where "which" sets the direction indicator, D:
458 0 -- sent to network, or ">"
459 1 -- rcvd and printed to stdout, or "<"
460 and "buf" and "n" are data-block and length. If the current block generates
461 a partial line, so be it; we *want* that lockstep indication of who sent
462 what when. Adapted from dgaudet's original example -- but must be ripping
463 *fast*, since we don't want to be too disk-bound... */
Denis Vlasenko19507f02007-04-06 10:41:05 +0000464#if ENABLE_NC_EXTRA
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000465static void oprint(int direction, unsigned char *p, unsigned bc)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000466{
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000467 unsigned obc; /* current "global" offset */
468 unsigned x;
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000469 unsigned char *op; /* out hexdump ptr */
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000470 unsigned char *ap; /* out asc-dump ptr */
Denis Vlasenko19507f02007-04-06 10:41:05 +0000471 unsigned char stage[100];
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000472
Denis Vlasenko19507f02007-04-06 10:41:05 +0000473 if (bc == 0)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000474 return;
475
Denis Vlasenko19507f02007-04-06 10:41:05 +0000476 obc = wrote_net; /* use the globals! */
477 if (direction == '<')
478 obc = wrote_out;
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000479 stage[0] = direction;
480 stage[59] = '#'; /* preload separator */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000481 stage[60] = ' ';
482
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000483 do { /* for chunk-o-data ... */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000484 x = 16;
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000485 if (bc < 16) {
486 /* memset(&stage[bc*3 + 11], ' ', 16*3 - bc*3); */
487 memset(&stage[11], ' ', 16*3);
488 x = bc;
489 }
490 sprintf(&stage[1], " %8.8x ", obc); /* xxx: still slow? */
491 bc -= x; /* fix current count */
492 obc += x; /* fix current offset */
493 op = &stage[11]; /* where hex starts */
494 ap = &stage[61]; /* where ascii starts */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000495
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000496 do { /* for line of dump, however long ... */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000497 *op++ = 0x20 | bb_hexdigits_upcase[*p >> 4];
498 *op++ = 0x20 | bb_hexdigits_upcase[*p & 0x0f];
499 *op++ = ' ';
500 if ((*p > 31) && (*p < 127))
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000501 *ap = *p; /* printing */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000502 else
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000503 *ap = '.'; /* nonprinting, loose def */
504 ap++;
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000505 p++;
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000506 } while (--x);
507 *ap++ = '\n'; /* finish the line */
508 xwrite(ofd, stage, ap - stage);
509 } while (bc);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000510}
Denis Vlasenko19507f02007-04-06 10:41:05 +0000511#else
Denis Vlasenko828e2a92007-07-13 12:37:31 +0000512void oprint(int direction, unsigned char *p, unsigned bc);
Denis Vlasenko19507f02007-04-06 10:41:05 +0000513#endif
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000514
515/* readwrite:
516 handle stdin/stdout/network I/O. Bwahaha!! -- the select loop from hell.
517 In this instance, return what might become our exit status. */
518static int readwrite(void)
519{
520 int rr;
521 char *zp = zp; /* gcc */ /* stdin buf ptr */
522 char *np = np; /* net-in buf ptr */
523 unsigned rzleft;
524 unsigned rnleft;
525 unsigned netretry; /* net-read retry counter */
526 unsigned wretry; /* net-write sanity counter */
527 unsigned wfirst; /* one-shot flag to skip first net read */
528
529 /* if you don't have all this FD_* macro hair in sys/types.h, you'll have to
530 either find it or do your own bit-bashing: *ding1 |= (1 << fd), etc... */
531 FD_SET(netfd, &ding1); /* global: the net is open */
532 netretry = 2;
533 wfirst = 0;
534 rzleft = rnleft = 0;
535 if (o_interval)
536 sleep(o_interval); /* pause *before* sending stuff, too */
537
538 errno = 0; /* clear from sleep, close, whatever */
539 /* and now the big ol' select shoveling loop ... */
540 while (FD_ISSET(netfd, &ding1)) { /* i.e. till the *net* closes! */
541 wretry = 8200; /* more than we'll ever hafta write */
542 if (wfirst) { /* any saved stdin buffer? */
543 wfirst = 0; /* clear flag for the duration */
544 goto shovel; /* and go handle it first */
545 }
546 ding2 = ding1; /* FD_COPY ain't portable... */
547 /* some systems, notably linux, crap into their select timers on return, so
548 we create a expendable copy and give *that* to select. */
549 if (o_wait) {
550 struct timeval tmp_timer;
551 tmp_timer.tv_sec = o_wait;
552 tmp_timer.tv_usec = 0;
Denis Vlasenko19507f02007-04-06 10:41:05 +0000553 /* highest possible fd is netfd (3) */
554 rr = select(netfd+1, &ding2, NULL, NULL, &tmp_timer);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000555 } else
Denis Vlasenko19507f02007-04-06 10:41:05 +0000556 rr = select(netfd+1, &ding2, NULL, NULL, NULL);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000557 if (rr < 0 && errno != EINTR) { /* might have gotten ^Zed, etc */
558 holler_perror("select");
559 close(netfd);
560 return 1;
561 }
562 /* if we have a timeout AND stdin is closed AND we haven't heard anything
563 from the net during that time, assume it's dead and close it too. */
564 if (rr == 0) {
565 if (!FD_ISSET(0, &ding1))
566 netretry--; /* we actually try a coupla times. */
567 if (!netretry) {
568 if (o_verbose > 1) /* normally we don't care */
569 fprintf(stderr, "net timeout\n");
570 close(netfd);
571 return 0; /* not an error! */
572 }
573 } /* select timeout */
574 /* xxx: should we check the exception fds too? The read fds seem to give
575 us the right info, and none of the examples I found bothered. */
576
577 /* Ding!! Something arrived, go check all the incoming hoppers, net first */
578 if (FD_ISSET(netfd, &ding2)) { /* net: ding! */
579 rr = read(netfd, bigbuf_net, BIGSIZ);
580 if (rr <= 0) {
Denis Vlasenko19507f02007-04-06 10:41:05 +0000581 if (rr < 0 && o_verbose > 1) {
582 /* nc 1.10 doesn't do this */
583 bb_perror_msg("net read");
584 }
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000585 FD_CLR(netfd, &ding1); /* net closed, we'll finish up... */
586 rzleft = 0; /* can't write anymore: broken pipe */
587 } else {
588 rnleft = rr;
589 np = bigbuf_net;
590 }
Denis Vlasenko19507f02007-04-06 10:41:05 +0000591Debug("got %d from the net, errno %d", rr, errno);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000592 } /* net:ding */
593
594 /* if we're in "slowly" mode there's probably still stuff in the stdin
595 buffer, so don't read unless we really need MORE INPUT! MORE INPUT! */
596 if (rzleft)
597 goto shovel;
598
599 /* okay, suck more stdin */
600 if (FD_ISSET(0, &ding2)) { /* stdin: ding! */
601 rr = read(0, bigbuf_in, BIGSIZ);
602 /* Considered making reads here smaller for UDP mode, but 8192-byte
603 mobygrams are kinda fun and exercise the reassembler. */
604 if (rr <= 0) { /* at end, or fukt, or ... */
605 FD_CLR(0, &ding1); /* disable and close stdin */
606 close(0);
607 } else {
608 rzleft = rr;
609 zp = bigbuf_in;
610 }
611 } /* stdin:ding */
612 shovel:
613 /* now that we've dingdonged all our thingdings, send off the results.
614 Geez, why does this look an awful lot like the big loop in "rsh"? ...
615 not sure if the order of this matters, but write net -> stdout first. */
616
617 /* sanity check. Works because they're both unsigned... */
618 if ((rzleft > 8200) || (rnleft > 8200)) {
619 holler_error("bogus buffers: %u, %u", rzleft, rnleft);
620 rzleft = rnleft = 0;
621 }
622 /* net write retries sometimes happen on UDP connections */
623 if (!wretry) { /* is something hung? */
624 holler_error("too many output retries");
625 return 1;
626 }
627 if (rnleft) {
628 rr = write(1, np, rnleft);
629 if (rr > 0) {
Denis Vlasenko19507f02007-04-06 10:41:05 +0000630 if (o_ofile)
631 oprint('<', np, rr); /* log the stdout */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000632 np += rr; /* fix up ptrs and whatnot */
633 rnleft -= rr; /* will get sanity-checked above */
634 wrote_out += rr; /* global count */
635 }
Denis Vlasenko19507f02007-04-06 10:41:05 +0000636Debug("wrote %d to stdout, errno %d", rr, errno);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000637 } /* rnleft */
638 if (rzleft) {
639 if (o_interval) /* in "slowly" mode ?? */
640 rr = findline(zp, rzleft);
641 else
642 rr = rzleft;
643 rr = write(netfd, zp, rr); /* one line, or the whole buffer */
644 if (rr > 0) {
Denis Vlasenko19507f02007-04-06 10:41:05 +0000645 if (o_ofile)
646 oprint('>', zp, rr); /* log what got sent */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000647 zp += rr;
648 rzleft -= rr;
649 wrote_net += rr; /* global count */
650 }
Denis Vlasenko19507f02007-04-06 10:41:05 +0000651Debug("wrote %d to net, errno %d", rr, errno);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000652 } /* rzleft */
653 if (o_interval) { /* cycle between slow lines, or ... */
654 sleep(o_interval);
655 errno = 0; /* clear from sleep */
656 continue; /* ...with hairy select loop... */
657 }
658 if ((rzleft) || (rnleft)) { /* shovel that shit till they ain't */
659 wretry--; /* none left, and get another load */
660 goto shovel;
661 }
662 } /* while ding1:netfd is open */
663
664 /* XXX: maybe want a more graceful shutdown() here, or screw around with
665 linger times?? I suspect that I don't need to since I'm always doing
666 blocking reads and writes and my own manual "last ditch" efforts to read
667 the net again after a timeout. I haven't seen any screwups yet, but it's
668 not like my test network is particularly busy... */
669 close(netfd);
670 return 0;
671} /* readwrite */
672
673/* main: now we pull it all together... */
Denis Vlasenko9b49a5e2007-10-11 10:05:36 +0000674int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000675int nc_main(int argc, char **argv)
676{
677 char *str_p, *str_s, *str_w;
Denis Vlasenko19507f02007-04-06 10:41:05 +0000678 USE_NC_EXTRA(char *str_i, *str_o;)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000679 char *themdotted = themdotted; /* gcc */
680 char **proggie;
681 int x;
682 unsigned o_lport = 0;
683
Denis Vlasenko574f2f42008-02-27 18:41:59 +0000684 INIT_G();
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000685
686 /* catch a signal or two for cleanup */
Denis Vlasenko25591c32008-02-16 22:58:56 +0000687 bb_signals(0
688 + (1 << SIGINT)
689 + (1 << SIGQUIT)
690 + (1 << SIGTERM)
691 , catch);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000692 /* and suppress others... */
Denis Vlasenko25591c32008-02-16 22:58:56 +0000693 bb_signals(0
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000694#ifdef SIGURG
Denis Vlasenko25591c32008-02-16 22:58:56 +0000695 + (1 << SIGURG)
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000696#endif
Denis Vlasenko25591c32008-02-16 22:58:56 +0000697 + (1 << SIGPIPE) /* important! */
698 , SIG_IGN);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000699
700 proggie = argv;
701 while (*++proggie) {
702 if (strcmp(*proggie, "-e") == 0) {
703 *proggie = NULL;
704 argc = proggie - argv;
705 proggie++;
706 goto e_found;
707 }
708 }
709 proggie = NULL;
710 e_found:
Denis Vlasenko4b924f32007-05-30 00:29:55 +0000711
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000712 // -g -G -t -r deleted, unimplemented -a deleted too
713 opt_complementary = "?2:vv"; /* max 2 params, -v is a counter */
Denis Vlasenkofe7cd642007-08-18 15:32:12 +0000714 getopt32(argv, "hnp:s:uvw:" USE_NC_SERVER("l")
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000715 USE_NC_EXTRA("i:o:z"),
716 &str_p, &str_s, &str_w
Denis Vlasenko19507f02007-04-06 10:41:05 +0000717 USE_NC_EXTRA(, &str_i, &str_o, &o_verbose));
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000718 argv += optind;
719#if ENABLE_NC_EXTRA
720 if (option_mask32 & OPT_i) /* line-interval time */
721 o_interval = xatou_range(str_i, 1, 0xffff);
722#endif
723 //if (option_mask32 & OPT_l) /* listen mode */
724 //if (option_mask32 & OPT_n) /* numeric-only, no DNS lookups */
725 //if (option_mask32 & OPT_o) /* hexdump log */
726 if (option_mask32 & OPT_p) { /* local source port */
727 o_lport = bb_lookup_port(str_p, o_udpmode ? "udp" : "tcp", 0);
728 if (!o_lport)
729 bb_error_msg_and_die("bad local port '%s'", str_p);
730 }
731 //if (option_mask32 & OPT_r) /* randomize various things */
732 //if (option_mask32 & OPT_u) /* use UDP */
733 //if (option_mask32 & OPT_v) /* verbose */
734 if (option_mask32 & OPT_w) { /* wait time */
735 o_wait = xatoi_u(str_w);
736 }
737 //if (option_mask32 & OPT_z) /* little or no data xfer */
738
Denis Vlasenko19507f02007-04-06 10:41:05 +0000739 /* We manage our fd's so that they are never 0,1,2 */
740 /*bb_sanitize_stdio(); - not needed */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000741
Denis Vlasenko5c51a7c2007-06-05 20:08:11 +0000742 if (argv[0]) {
743 themaddr = xhost2sockaddr(argv[0],
744 argv[1]
745 ? bb_lookup_port(argv[1], o_udpmode ? "udp" : "tcp", 0)
746 : 0);
747 }
748
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000749 /* create & bind network socket */
Denis Vlasenko19507f02007-04-06 10:41:05 +0000750 x = (o_udpmode ? SOCK_DGRAM : SOCK_STREAM);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000751 if (option_mask32 & OPT_s) { /* local address */
Denis Vlasenko19507f02007-04-06 10:41:05 +0000752 /* if o_lport is still 0, then we will use random port */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000753 ouraddr = xhost2sockaddr(str_s, o_lport);
Denis Vlasenko4cf1d082008-03-12 23:13:50 +0000754#ifdef BLOAT
755 /* prevent spurious "UDP listen needs !0 port" */
756 o_lport = get_nport(ouraddr);
757 o_lport = ntohs(o_lport);
758#endif
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000759 x = xsocket(ouraddr->u.sa.sa_family, x, 0);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000760 } else {
Denis Vlasenko5c51a7c2007-06-05 20:08:11 +0000761 /* We try IPv6, then IPv4, unless addr family is
762 * implicitly set by way of remote addr/port spec */
763 x = xsocket_type(&ouraddr,
Denis Vlasenko4e6d5112008-03-12 22:14:34 +0000764 (themaddr ? themaddr->u.sa.sa_family : AF_UNSPEC),
Denis Vlasenko5c51a7c2007-06-05 20:08:11 +0000765 x);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000766 if (o_lport)
767 set_nport(ouraddr, htons(o_lport));
768 }
Denis Vlasenko19507f02007-04-06 10:41:05 +0000769 xmove_fd(x, netfd);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000770 setsockopt_reuseaddr(netfd);
771 if (o_udpmode)
772 socket_want_pktinfo(netfd);
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000773 xbind(netfd, &ouraddr->u.sa, ouraddr->len);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000774#if 0
775 setsockopt(netfd, SOL_SOCKET, SO_RCVBUF, &o_rcvbuf, sizeof o_rcvbuf);
776 setsockopt(netfd, SOL_SOCKET, SO_SNDBUF, &o_sndbuf, sizeof o_sndbuf);
777#endif
778
Denis Vlasenko4cf1d082008-03-12 23:13:50 +0000779#ifdef BLOAT
Denis Vlasenko19507f02007-04-06 10:41:05 +0000780 if (OPT_l && (option_mask32 & (OPT_u|OPT_l)) == (OPT_u|OPT_l)) {
781 /* apparently UDP can listen ON "port 0",
782 but that's not useful */
783 if (!o_lport)
784 bb_error_msg_and_die("UDP listen needs nonzero -p port");
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000785 }
Denis Vlasenko4cf1d082008-03-12 23:13:50 +0000786#endif
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000787
788 FD_SET(0, &ding1); /* stdin *is* initially open */
789 if (proggie) {
790 close(0); /* won't need stdin */
791 option_mask32 &= ~OPT_o; /* -o with -e is meaningless! */
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000792 }
Denis Vlasenko19507f02007-04-06 10:41:05 +0000793#if ENABLE_NC_EXTRA
794 if (o_ofile)
795 xmove_fd(xopen(str_o, O_WRONLY|O_CREAT|O_TRUNC), ofd);
796#endif
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000797
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000798 if (o_listen) {
799 dolisten();
800 /* dolisten does its own connect reporting */
801 if (proggie) /* -e given? */
802 doexec(proggie);
803 x = readwrite(); /* it even works with UDP! */
804 } else {
805 /* Outbound connects. Now we're more picky about args... */
806 if (!themaddr)
807 bb_error_msg_and_die("no destination");
808
809 remend = *themaddr;
810 if (o_verbose)
Denis Vlasenko7cff01e2008-02-02 16:23:43 +0000811 themdotted = xmalloc_sockaddr2dotted(&themaddr->u.sa);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000812
813 x = connect_w_timeout(netfd);
814 if (o_zero && x == 0 && o_udpmode) /* if UDP scanning... */
815 x = udptest();
816 if (x == 0) { /* Yow, are we OPEN YET?! */
817 if (o_verbose)
Denis Vlasenko19507f02007-04-06 10:41:05 +0000818 fprintf(stderr, "%s (%s) open\n", argv[0], themdotted);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000819 if (proggie) /* exec is valid for outbound, too */
820 doexec(proggie);
821 if (!o_zero)
822 x = readwrite();
823 } else { /* connect or udptest wasn't successful */
824 x = 1; /* exit status */
825 /* if we're scanning at a "one -v" verbosity level, don't print refusals.
826 Give it another -v if you want to see everything. */
827 if (o_verbose > 1 || (o_verbose && errno != ECONNREFUSED))
Denis Vlasenko19507f02007-04-06 10:41:05 +0000828 bb_perror_msg("%s (%s)", argv[0], themdotted);
Denis Vlasenko29fe7262007-04-05 20:26:28 +0000829 }
830 }
831 if (o_verbose > 1) /* normally we don't care */
832 fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out);
833 return x;
834}