1 /* Based on netcat 1.10 RELEASE 960320 written by hobbit@avian.org.
2 * Released into public domain by the author.
4 * Copyright (C) 2007 Denys Vlasenko.
6 * Licensed under GPLv2, see file LICENSE in this source tree.
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.
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
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 * =====================
31 * Much of author's comments are still retained in the code.
33 * Functionality removed (rationale):
34 * - miltiple-port ranges, randomized port scanning (use nmap)
35 * - telnet support (use telnet)
37 * - multiple DNS checks
38 * Functionalty which is different from nc 1.10:
39 * - PROG in '-e PROG' can have ARGS (and options).
40 * Because of this -e option must be last.
41 //TODO: remove -e incompatibility?
42 * - we don't redirect stderr to the network socket for the -e PROG.
43 * (PROG can do it itself if needed, but sometimes it is NOT wanted!)
44 * - numeric addresses are printed in (), not [] (IPv6 looks better),
45 * port numbers are inside (): (1.2.3.4:5678)
46 * - network read errors are reported on verbose levels > 1
47 * (nc 1.10 treats them as EOF)
48 * - TCP connects from wrong ip/ports (if peer ip:port is specified
49 * on the command line, but accept() says that it came from different addr)
50 * are closed, but we don't exit - we continue to listen/accept.
53 /* done in nc.c: #include "libbb.h" */
55 //usage:#if ENABLE_NC_110_COMPAT
57 //usage:#define nc_trivial_usage
58 //usage: "[OPTIONS] HOST PORT - connect"
59 //usage: IF_NC_SERVER("\n"
60 //usage: "nc [OPTIONS] -l -p PORT [HOST] [PORT] - listen"
62 //usage:#define nc_full_usage "\n\n"
64 //usage: "\n -e PROG Run PROG after connect (must be last)"
65 //usage: IF_NC_SERVER(
66 //usage: "\n -l Listen mode, for inbound connects"
68 //usage: "\n -p PORT Local port"
69 //usage: "\n -s ADDR Local address"
70 //usage: "\n -w SEC Timeout for connects and final net reads"
72 //usage: "\n -i SEC Delay interval for lines sent" /* ", ports scanned" */
74 //usage: "\n -n Don't do DNS resolution"
75 //usage: "\n -u UDP mode"
76 //usage: "\n -v Verbose"
78 //usage: "\n -o FILE Hex dump traffic"
79 //usage: "\n -z Zero-I/O mode (scanning)"
83 /* "\n -r Randomize local and remote ports" */
84 /* "\n -g gateway Source-routing hop point[s], up to 8" */
85 /* "\n -G num Source-routing pointer: 4, 8, 12, ..." */
86 /* "\nport numbers can be individual or ranges: lo-hi [inclusive]" */
88 /* -e PROG can take ARGS too: "nc ... -e ls -l", but we don't document it
89 * in help text: nc 1.10 does not allow that. We don't want to entice
90 * users to use this incompatibility */
93 SLEAZE_PORT = 31337, /* for UDP-scan RTT trick, change if ya want */
94 BIGSIZ = 8192, /* big buffers */
101 /* global cmd flags: */
109 /*int ofd;*/ /* hexdump output fd */
111 #define SENT_N_RECV_M "sent %llu, rcvd %llu\n"
112 unsigned long long wrote_out; /* total stdout bytes */
113 unsigned long long wrote_net; /* total net bytes */
115 #define SENT_N_RECV_M "sent %u, rcvd %u\n"
116 unsigned wrote_out; /* total stdout bytes */
117 unsigned wrote_net; /* total net bytes */
119 /* ouraddr is never NULL and goes through three states as we progress:
120 1 - local address before bind (IP/port possibly zero)
121 2 - local address after bind (port is nonzero)
122 3 - local address after connect??/recv/accept (IP and port are nonzero) */
123 struct len_and_sockaddr *ouraddr;
124 /* themaddr is NULL if no peer hostname[:port] specified on command line */
125 struct len_and_sockaddr *themaddr;
126 /* remend is set after connect/recv/accept to the actual ip:port of peer */
127 struct len_and_sockaddr remend;
129 jmp_buf jbuf; /* timer crud */
131 /* will malloc up the following globals: */
132 fd_set ding1; /* for select loop */
134 char bigbuf_in[BIGSIZ]; /* data buffers */
135 char bigbuf_net[BIGSIZ];
138 #define G (*ptr_to_globals)
139 #define wrote_out (G.wrote_out )
140 #define wrote_net (G.wrote_net )
141 #define ouraddr (G.ouraddr )
142 #define themaddr (G.themaddr )
143 #define remend (G.remend )
144 #define jbuf (G.jbuf )
145 #define ding1 (G.ding1 )
146 #define ding2 (G.ding2 )
147 #define bigbuf_in (G.bigbuf_in )
148 #define bigbuf_net (G.bigbuf_net)
149 #define o_verbose (G.o_verbose )
150 #define o_wait (G.o_wait )
152 #define o_interval (G.o_interval)
156 #define INIT_G() do { \
157 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
161 /* Must match getopt32 call! */
170 OPT_l = (1 << 7) * ENABLE_NC_SERVER,
171 OPT_i = (1 << (7+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
172 OPT_o = (1 << (8+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
173 OPT_z = (1 << (9+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
176 #define o_nflag (option_mask32 & OPT_n)
177 #define o_udpmode (option_mask32 & OPT_u)
179 #define o_listen (option_mask32 & OPT_l)
184 #define o_ofile (option_mask32 & OPT_o)
185 #define o_zero (option_mask32 & OPT_z)
191 /* Debug: squirt whatever message and sleep a bit so we can see it go by. */
192 /* Beware: writes to stdOUT... */
194 #define Debug(...) do { printf(__VA_ARGS__); printf("\n"); fflush_all(); sleep(1); } while (0)
196 #define Debug(...) do { } while (0)
199 #define holler_error(...) do { if (o_verbose) bb_error_msg(__VA_ARGS__); } while (0)
200 #define holler_perror(...) do { if (o_verbose) bb_perror_msg(__VA_ARGS__); } while (0)
202 /* catch: no-brainer interrupt handler */
203 static void catch(int sig)
205 if (o_verbose > 1) /* normally we don't care */
206 fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out);
207 fprintf(stderr, "punt!\n");
208 kill_myself_with_sig(sig);
212 static void unarm(void)
214 signal(SIGALRM, SIG_IGN);
218 /* timeout and other signal handling cruft */
219 static void tmtravel(int sig UNUSED_PARAM)
225 /* arm: set the timer. */
226 static void arm(unsigned secs)
228 signal(SIGALRM, tmtravel);
233 find the next newline in a buffer; return inclusive size of that "line",
234 or the entire buffer size, so the caller knows how much to then write().
235 Not distinguishing \n vs \r\n for the nonce; it just works as is... */
236 static unsigned findline(char *buf, unsigned siz)
240 if (!buf) /* various sanity checks... */
245 for (p = buf; x > 0; x--) {
248 x++; /* 'sokay if it points just past the end! */
249 Debug("findline returning %d", x);
254 Debug("findline returning whole thing: %d", siz);
259 fiddle all the file descriptors around, and hand off to another prog. Sort
260 of like a one-off "poor man's inetd". This is the only section of code
261 that would be security-critical, which is why it's ifdefed out by default.
262 Use at your own hairy risk; if you leave shells lying around behind open
263 listening ports you deserve to lose!! */
264 static int doexec(char **proggie) NORETURN;
265 static int doexec(char **proggie)
269 /* dup2(0, 2); - do we *really* want this? NO!
270 * exec'ed prog can do it yourself, if needed */
271 execvp(proggie[0], proggie);
272 bb_perror_msg_and_die("can't execute '%s'", proggie[0]);
275 /* connect_w_timeout:
276 return an fd for one of
277 an open outbound TCP connection, a UDP stub-socket thingie, or
278 an unconnected TCP or UDP socket to listen on.
279 Examines various global o_blah flags to figure out what to do.
280 lad can be NULL, then socket is not bound to any local ip[:port] */
281 static int connect_w_timeout(int fd)
285 /* wrap connect inside a timer, and hit it */
287 if (setjmp(jbuf) == 0) {
288 rr = connect(fd, &themaddr->u.sa, themaddr->len);
290 } else { /* setjmp: connect failed... */
292 errno = ETIMEDOUT; /* fake it */
299 incoming and returns an open connection *from* someplace. If we were
300 given host/port args, any connections from elsewhere are rejected. This
301 in conjunction with local-address binding should limit things nicely... */
302 static void dolisten(void)
307 xlisten(netfd, 1); /* TCP: gotta listen() before we can get */
309 /* Various things that follow temporarily trash bigbuf_net, which might contain
310 a copy of any recvfrom()ed packet, but we'll read() another copy later. */
312 /* I can't believe I have to do all this to get my own goddamn bound address
313 and port number. It should just get filled in during bind() or something.
314 All this is only useful if we didn't say -p for listening, since if we
315 said -p we *know* what port we're listening on. At any rate we won't bother
316 with it all unless we wanted to see it, although listening quietly on a
317 random unknown port is probably not very useful without "netstat". */
320 getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
322 // bb_perror_msg_and_die("getsockname after bind");
323 addr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
324 fprintf(stderr, "listening on %s ...\n", addr);
329 /* UDP is a speeeeecial case -- we have to do I/O *and* get the calling
330 party's particulars all at once, listen() and accept() don't apply.
331 At least in the BSD universe, however, recvfrom/PEEK is enough to tell
332 us something came in, and we can set things up so straight read/write
333 actually does work after all. Yow. YMMV on strange platforms! */
335 /* I'm not completely clear on how this works -- BSD seems to make UDP
336 just magically work in a connect()ed context, but we'll undoubtedly run
337 into systems this deal doesn't work on. For now, we apparently have to
338 issue a connect() on our just-tickled socket so we can write() back.
339 Again, why the fuck doesn't it just get filled in and taken care of?!
340 This hack is anything but optimal. Basically, if you want your listener
341 to also be able to send data back, you need this connect() line, which
342 also has the side effect that now anything from a different source or even a
343 different port on the other end won't show up and will cause ICMP errors.
344 I guess that's what they meant by "connect".
345 Let's try to remember what the "U" is *really* for, eh? */
347 /* If peer address is specified, connect to it */
348 remend.len = LSA_SIZEOF_SA;
351 xconnect(netfd, &themaddr->u.sa, themaddr->len);
353 /* peek first packet and remember peer addr */
354 arm(o_wait); /* might as well timeout this, too */
355 if (setjmp(jbuf) == 0) { /* do timeout for initial connect */
356 /* (*ouraddr) is prefilled with "default" address */
357 /* and here we block... */
358 rr = recv_from_to(netfd, NULL, 0, MSG_PEEK, /*was bigbuf_net, BIGSIZ*/
359 &remend.u.sa, &ouraddr->u.sa, ouraddr->len);
361 bb_perror_msg_and_die("recvfrom");
364 bb_error_msg_and_die("timeout");
365 /* Now we learned *to which IP* peer has connected, and we want to anchor
366 our socket on it, so that our outbound packets will have correct local IP.
367 Unfortunately, bind() on already bound socket will fail now (EINVAL):
368 xbind(netfd, &ouraddr->u.sa, ouraddr->len);
369 Need to read the packet, save data, close this socket and
370 create new one, and bind() it. TODO */
372 xconnect(netfd, &remend.u.sa, ouraddr->len);
375 arm(o_wait); /* wrap this in a timer, too; 0 = forever */
376 if (setjmp(jbuf) == 0) {
378 remend.len = LSA_SIZEOF_SA;
379 rr = accept(netfd, &remend.u.sa, &remend.len);
381 bb_perror_msg_and_die("accept");
383 int sv_port, port, r;
385 sv_port = get_nport(&remend.u.sa); /* save */
386 port = get_nport(&themaddr->u.sa);
388 /* "nc -nl -p LPORT RHOST" (w/o RPORT!):
389 * we should accept any remote port */
390 set_nport(&remend, 0); /* blot out remote port# */
392 r = memcmp(&remend.u.sa, &themaddr->u.sa, remend.len);
393 set_nport(&remend, sv_port); /* restore */
395 /* nc 1.10 bails out instead, and its error message
396 * is not suppressed by o_verbose */
398 char *remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
399 bb_error_msg("connect from wrong ip/port %s ignored", remaddr);
408 bb_error_msg_and_die("timeout");
409 xmove_fd(rr, netfd); /* dump the old socket, here's our new one */
410 /* find out what address the connection was *to* on our end, in case we're
411 doing a listen-on-any on a multihomed machine. This allows one to
412 offer different services via different alias addresses, such as the
413 "virtual web site" hack. */
414 getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
416 // bb_perror_msg_and_die("getsockname after accept");
420 char *lcladdr, *remaddr, *remhostname;
422 #if ENABLE_NC_EXTRA && defined(IP_OPTIONS)
423 /* If we can, look for any IP options. Useful for testing the receiving end of
424 such things, and is a good exercise in dealing with it. We do this before
425 the connect message, to ensure that the connect msg is uniformly the LAST
426 thing to emerge after all the intervening crud. Doesn't work for UDP on
427 any machines I've tested, but feel free to surprise me. */
429 socklen_t x = sizeof(optbuf);
431 rr = getsockopt(netfd, IPPROTO_IP, IP_OPTIONS, optbuf, &x);
432 if (rr >= 0 && x) { /* we've got options, lessee em... */
433 bin2hex(bigbuf_net, optbuf, x);
434 bigbuf_net[2*x] = '\0';
435 fprintf(stderr, "IP options: %s\n", bigbuf_net);
439 /* now check out who it is. We don't care about mismatched DNS names here,
440 but any ADDR and PORT we specified had better fucking well match the caller.
441 Converting from addr to inet_ntoa and back again is a bit of a kludge, but
442 gethostpoop wants a string and there's much gnarlier code out there already,
444 The *real* question is why BFD sockets wasn't designed to allow listens for
445 connections *from* specific hosts/ports, instead of requiring the caller to
446 accept the connection and then reject undesireable ones by closing.
447 In other words, we need a TCP MSG_PEEK. */
448 /* bbox: removed most of it */
449 lcladdr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
450 remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
451 remhostname = o_nflag ? remaddr : xmalloc_sockaddr2host(&remend.u.sa);
452 fprintf(stderr, "connect to %s from %s (%s)\n",
453 lcladdr, remhostname, remaddr);
462 fire a couple of packets at a UDP target port, just to see if it's really
463 there. On BSD kernels, ICMP host/port-unreachable errors get delivered to
464 our socket as ECONNREFUSED write errors. On SV kernels, we lose; we'll have
465 to collect and analyze raw ICMP ourselves a la satan's probe_udp_ports
466 backend. Guess where one could swipe the appropriate code from...
468 Use the time delay between writes if given, otherwise use the "tcp ping"
469 trick for getting the RTT. [I got that idea from pluvius, and warped it.]
470 Return either the original fd, or clean up and return -1. */
472 static int udptest(void)
476 rr = write(netfd, bigbuf_in, 1);
478 bb_perror_msg("udptest first write");
481 sleep(o_wait); // can be interrupted! while (t) nanosleep(&t)?
483 /* use the tcp-ping trick: try connecting to a normally refused port, which
484 causes us to block for the time that SYN gets there and RST gets back.
485 Not completely reliable, but it *does* mostly work. */
486 /* Set a temporary connect timeout, so packet filtration doesnt cause
487 us to hang forever, and hit it */
488 o_wait = 5; /* enough that we'll notice?? */
489 rr = xsocket(ouraddr->u.sa.sa_family, SOCK_STREAM, 0);
490 set_nport(themaddr, htons(SLEAZE_PORT));
491 connect_w_timeout(rr);
492 /* don't need to restore themaddr's port, it's not used anymore */
494 o_wait = 0; /* restore */
497 rr = write(netfd, bigbuf_in, 1);
498 return (rr != 1); /* if rr == 1, return 0 (success) */
505 Hexdump bytes shoveled either way to a running logfile, in the format:
506 D offset - - - - --- 16 bytes --- - - - - # .... ascii .....
507 where "which" sets the direction indicator, D:
508 0 -- sent to network, or ">"
509 1 -- rcvd and printed to stdout, or "<"
510 and "buf" and "n" are data-block and length. If the current block generates
511 a partial line, so be it; we *want* that lockstep indication of who sent
512 what when. Adapted from dgaudet's original example -- but must be ripping
513 *fast*, since we don't want to be too disk-bound... */
515 static void oprint(int direction, unsigned char *p, unsigned bc)
517 unsigned obc; /* current "global" offset */
519 unsigned char *op; /* out hexdump ptr */
520 unsigned char *ap; /* out asc-dump ptr */
521 unsigned char stage[100];
526 obc = wrote_net; /* use the globals! */
527 if (direction == '<')
529 stage[0] = direction;
530 stage[59] = '#'; /* preload separator */
533 do { /* for chunk-o-data ... */
536 /* memset(&stage[bc*3 + 11], ' ', 16*3 - bc*3); */
537 memset(&stage[11], ' ', 16*3);
540 sprintf((char *)&stage[1], " %8.8x ", obc); /* xxx: still slow? */
541 bc -= x; /* fix current count */
542 obc += x; /* fix current offset */
543 op = &stage[11]; /* where hex starts */
544 ap = &stage[61]; /* where ascii starts */
546 do { /* for line of dump, however long ... */
547 *op++ = 0x20 | bb_hexdigits_upcase[*p >> 4];
548 *op++ = 0x20 | bb_hexdigits_upcase[*p & 0x0f];
550 if ((*p > 31) && (*p < 127))
551 *ap = *p; /* printing */
553 *ap = '.'; /* nonprinting, loose def */
557 *ap++ = '\n'; /* finish the line */
558 xwrite(ofd, stage, ap - stage);
562 void oprint(int direction, unsigned char *p, unsigned bc);
566 handle stdin/stdout/network I/O. Bwahaha!! -- the select loop from hell.
567 In this instance, return what might become our exit status. */
568 static int readwrite(void)
571 char *zp = zp; /* gcc */ /* stdin buf ptr */
572 char *np = np; /* net-in buf ptr */
575 unsigned netretry; /* net-read retry counter */
576 unsigned wretry; /* net-write sanity counter */
577 unsigned wfirst; /* one-shot flag to skip first net read */
579 /* if you don't have all this FD_* macro hair in sys/types.h, you'll have to
580 either find it or do your own bit-bashing: *ding1 |= (1 << fd), etc... */
581 FD_SET(netfd, &ding1); /* global: the net is open */
586 sleep(o_interval); /* pause *before* sending stuff, too */
588 errno = 0; /* clear from sleep, close, whatever */
589 /* and now the big ol' select shoveling loop ... */
590 while (FD_ISSET(netfd, &ding1)) { /* i.e. till the *net* closes! */
591 wretry = 8200; /* more than we'll ever hafta write */
592 if (wfirst) { /* any saved stdin buffer? */
593 wfirst = 0; /* clear flag for the duration */
594 goto shovel; /* and go handle it first */
596 ding2 = ding1; /* FD_COPY ain't portable... */
597 /* some systems, notably linux, crap into their select timers on return, so
598 we create a expendable copy and give *that* to select. */
600 struct timeval tmp_timer;
601 tmp_timer.tv_sec = o_wait;
602 tmp_timer.tv_usec = 0;
603 /* highest possible fd is netfd (3) */
604 rr = select(netfd+1, &ding2, NULL, NULL, &tmp_timer);
606 rr = select(netfd+1, &ding2, NULL, NULL, NULL);
607 if (rr < 0 && errno != EINTR) { /* might have gotten ^Zed, etc */
608 holler_perror("select");
612 /* if we have a timeout AND stdin is closed AND we haven't heard anything
613 from the net during that time, assume it's dead and close it too. */
615 if (!FD_ISSET(STDIN_FILENO, &ding1))
616 netretry--; /* we actually try a coupla times. */
618 if (o_verbose > 1) /* normally we don't care */
619 fprintf(stderr, "net timeout\n");
621 return 0; /* not an error! */
623 } /* select timeout */
624 /* xxx: should we check the exception fds too? The read fds seem to give
625 us the right info, and none of the examples I found bothered. */
627 /* Ding!! Something arrived, go check all the incoming hoppers, net first */
628 if (FD_ISSET(netfd, &ding2)) { /* net: ding! */
629 rr = read(netfd, bigbuf_net, BIGSIZ);
631 if (rr < 0 && o_verbose > 1) {
632 /* nc 1.10 doesn't do this */
633 bb_perror_msg("net read");
635 FD_CLR(netfd, &ding1); /* net closed, we'll finish up... */
636 rzleft = 0; /* can't write anymore: broken pipe */
641 Debug("got %d from the net, errno %d", rr, errno);
644 /* if we're in "slowly" mode there's probably still stuff in the stdin
645 buffer, so don't read unless we really need MORE INPUT! MORE INPUT! */
649 /* okay, suck more stdin */
650 if (FD_ISSET(STDIN_FILENO, &ding2)) { /* stdin: ding! */
651 rr = read(STDIN_FILENO, bigbuf_in, BIGSIZ);
652 /* Considered making reads here smaller for UDP mode, but 8192-byte
653 mobygrams are kinda fun and exercise the reassembler. */
654 if (rr <= 0) { /* at end, or fukt, or ... */
655 FD_CLR(STDIN_FILENO, &ding1); /* disable and close stdin */
657 // Does it make sense to shutdown(net_fd, SHUT_WR)
658 // to let other side know that we won't write anything anymore?
659 // (and what about keeping compat if we do that?)
666 /* now that we've dingdonged all our thingdings, send off the results.
667 Geez, why does this look an awful lot like the big loop in "rsh"? ...
668 not sure if the order of this matters, but write net -> stdout first. */
670 /* sanity check. Works because they're both unsigned... */
671 if ((rzleft > 8200) || (rnleft > 8200)) {
672 holler_error("bogus buffers: %u, %u", rzleft, rnleft);
675 /* net write retries sometimes happen on UDP connections */
676 if (!wretry) { /* is something hung? */
677 holler_error("too many output retries");
681 rr = write(STDOUT_FILENO, np, rnleft);
683 if (o_ofile) /* log the stdout */
684 oprint('<', (unsigned char *)np, rr);
685 np += rr; /* fix up ptrs and whatnot */
686 rnleft -= rr; /* will get sanity-checked above */
687 wrote_out += rr; /* global count */
689 Debug("wrote %d to stdout, errno %d", rr, errno);
692 if (o_interval) /* in "slowly" mode ?? */
693 rr = findline(zp, rzleft);
696 rr = write(netfd, zp, rr); /* one line, or the whole buffer */
698 if (o_ofile) /* log what got sent */
699 oprint('>', (unsigned char *)zp, rr);
702 wrote_net += rr; /* global count */
704 Debug("wrote %d to net, errno %d", rr, errno);
706 if (o_interval) { /* cycle between slow lines, or ... */
708 errno = 0; /* clear from sleep */
709 continue; /* ...with hairy select loop... */
711 if ((rzleft) || (rnleft)) { /* shovel that shit till they ain't */
712 wretry--; /* none left, and get another load */
715 } /* while ding1:netfd is open */
717 /* XXX: maybe want a more graceful shutdown() here, or screw around with
718 linger times?? I suspect that I don't need to since I'm always doing
719 blocking reads and writes and my own manual "last ditch" efforts to read
720 the net again after a timeout. I haven't seen any screwups yet, but it's
721 not like my test network is particularly busy... */
726 /* main: now we pull it all together... */
727 int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
728 int nc_main(int argc UNUSED_PARAM, char **argv)
731 IF_NC_EXTRA(char *str_i, *str_o;)
732 char *themdotted = themdotted; /* gcc */
735 unsigned o_lport = 0;
739 /* catch a signal or two for cleanup */
745 /* and suppress others... */
750 + (1 << SIGPIPE) /* important! */
755 if (strcmp(*proggie, "-e") == 0) {
764 // -g -G -t -r deleted, unimplemented -a deleted too
765 opt_complementary = "?2:vv:w+"; /* max 2 params; -v is a counter; -w N */
766 getopt32(argv, "hnp:s:uvw:" IF_NC_SERVER("l")
767 IF_NC_EXTRA("i:o:z"),
768 &str_p, &str_s, &o_wait
769 IF_NC_EXTRA(, &str_i, &str_o), &o_verbose);
772 if (option_mask32 & OPT_i) /* line-interval time */
773 o_interval = xatou_range(str_i, 1, 0xffff);
775 //if (option_mask32 & OPT_l) /* listen mode */
776 //if (option_mask32 & OPT_n) /* numeric-only, no DNS lookups */
777 //if (option_mask32 & OPT_o) /* hexdump log */
778 if (option_mask32 & OPT_p) { /* local source port */
779 o_lport = bb_lookup_port(str_p, o_udpmode ? "udp" : "tcp", 0);
781 bb_error_msg_and_die("bad local port '%s'", str_p);
783 //if (option_mask32 & OPT_r) /* randomize various things */
784 //if (option_mask32 & OPT_u) /* use UDP */
785 //if (option_mask32 & OPT_v) /* verbose */
786 //if (option_mask32 & OPT_w) /* wait time */
787 //if (option_mask32 & OPT_z) /* little or no data xfer */
789 /* We manage our fd's so that they are never 0,1,2 */
790 /*bb_sanitize_stdio(); - not needed */
793 themaddr = xhost2sockaddr(argv[0],
795 ? bb_lookup_port(argv[1], o_udpmode ? "udp" : "tcp", 0)
799 /* create & bind network socket */
800 x = (o_udpmode ? SOCK_DGRAM : SOCK_STREAM);
801 if (option_mask32 & OPT_s) { /* local address */
802 /* if o_lport is still 0, then we will use random port */
803 ouraddr = xhost2sockaddr(str_s, o_lport);
805 /* prevent spurious "UDP listen needs !0 port" */
806 o_lport = get_nport(ouraddr);
807 o_lport = ntohs(o_lport);
809 x = xsocket(ouraddr->u.sa.sa_family, x, 0);
811 /* We try IPv6, then IPv4, unless addr family is
812 * implicitly set by way of remote addr/port spec */
813 x = xsocket_type(&ouraddr,
814 (themaddr ? themaddr->u.sa.sa_family : AF_UNSPEC),
817 set_nport(ouraddr, htons(o_lport));
820 setsockopt_reuseaddr(netfd);
822 socket_want_pktinfo(netfd);
823 if (!ENABLE_FEATURE_UNIX_LOCAL
825 || ouraddr->u.sa.sa_family != AF_UNIX
827 xbind(netfd, &ouraddr->u.sa, ouraddr->len);
830 setsockopt(netfd, SOL_SOCKET, SO_RCVBUF, &o_rcvbuf, sizeof o_rcvbuf);
831 setsockopt(netfd, SOL_SOCKET, SO_SNDBUF, &o_sndbuf, sizeof o_sndbuf);
835 if (OPT_l && (option_mask32 & (OPT_u|OPT_l)) == (OPT_u|OPT_l)) {
836 /* apparently UDP can listen ON "port 0",
837 but that's not useful */
839 bb_error_msg_and_die("UDP listen needs nonzero -p port");
843 FD_SET(STDIN_FILENO, &ding1); /* stdin *is* initially open */
845 close(0); /* won't need stdin */
846 option_mask32 &= ~OPT_o; /* -o with -e is meaningless! */
850 xmove_fd(xopen(str_o, O_WRONLY|O_CREAT|O_TRUNC), ofd);
855 /* dolisten does its own connect reporting */
856 if (proggie) /* -e given? */
858 x = readwrite(); /* it even works with UDP! */
860 /* Outbound connects. Now we're more picky about args... */
866 themdotted = xmalloc_sockaddr2dotted(&themaddr->u.sa);
868 x = connect_w_timeout(netfd);
869 if (o_zero && x == 0 && o_udpmode) /* if UDP scanning... */
871 if (x == 0) { /* Yow, are we OPEN YET?! */
873 fprintf(stderr, "%s (%s) open\n", argv[0], themdotted);
874 if (proggie) /* exec is valid for outbound, too */
878 } else { /* connect or udptest wasn't successful */
879 x = 1; /* exit status */
880 /* if we're scanning at a "one -v" verbosity level, don't print refusals.
881 Give it another -v if you want to see everything. */
882 if (o_verbose > 1 || (o_verbose && errno != ECONNREFUSED))
883 bb_perror_msg("%s (%s)", argv[0], themdotted);
886 if (o_verbose > 1) /* normally we don't care */
887 fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out);