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")
61 //usage:#define nc_full_usage "\n\n"
63 //usage: "\n -e PROG Run PROG after connect (must be last)"
64 //usage: IF_NC_SERVER(
65 //usage: "\n -l Listen mode, for inbound connects"
67 //usage: "\n -p PORT Local port"
68 //usage: "\n -s ADDR Local address"
69 //usage: "\n -w SEC Timeout for connects and final net reads"
71 //usage: "\n -i SEC Delay interval for lines sent" /* ", ports scanned" */
73 //usage: "\n -n Don't do DNS resolution"
74 //usage: "\n -u UDP mode"
75 //usage: "\n -v Verbose"
77 //usage: "\n -o FILE Hex dump traffic"
78 //usage: "\n -z Zero-I/O mode (scanning)"
82 /* "\n -r Randomize local and remote ports" */
83 /* "\n -g gateway Source-routing hop point[s], up to 8" */
84 /* "\n -G num Source-routing pointer: 4, 8, 12, ..." */
85 /* "\nport numbers can be individual or ranges: lo-hi [inclusive]" */
87 /* -e PROG can take ARGS too: "nc ... -e ls -l", but we don't document it
88 * in help text: nc 1.10 does not allow that. We don't want to entice
89 * users to use this incompatibility */
92 SLEAZE_PORT = 31337, /* for UDP-scan RTT trick, change if ya want */
93 BIGSIZ = 8192, /* big buffers */
100 /* global cmd flags: */
108 /*int ofd;*/ /* hexdump output fd */
110 #define SENT_N_RECV_M "sent %llu, rcvd %llu\n"
111 unsigned long long wrote_out; /* total stdout bytes */
112 unsigned long long wrote_net; /* total net bytes */
114 #define SENT_N_RECV_M "sent %u, rcvd %u\n"
115 unsigned wrote_out; /* total stdout bytes */
116 unsigned wrote_net; /* total net bytes */
118 /* ouraddr is never NULL and goes through three states as we progress:
119 1 - local address before bind (IP/port possibly zero)
120 2 - local address after bind (port is nonzero)
121 3 - local address after connect??/recv/accept (IP and port are nonzero) */
122 struct len_and_sockaddr *ouraddr;
123 /* themaddr is NULL if no peer hostname[:port] specified on command line */
124 struct len_and_sockaddr *themaddr;
125 /* remend is set after connect/recv/accept to the actual ip:port of peer */
126 struct len_and_sockaddr remend;
128 jmp_buf jbuf; /* timer crud */
130 /* will malloc up the following globals: */
131 fd_set ding1; /* for select loop */
133 char bigbuf_in[BIGSIZ]; /* data buffers */
134 char bigbuf_net[BIGSIZ];
137 #define G (*ptr_to_globals)
138 #define wrote_out (G.wrote_out )
139 #define wrote_net (G.wrote_net )
140 #define ouraddr (G.ouraddr )
141 #define themaddr (G.themaddr )
142 #define remend (G.remend )
143 #define jbuf (G.jbuf )
144 #define ding1 (G.ding1 )
145 #define ding2 (G.ding2 )
146 #define bigbuf_in (G.bigbuf_in )
147 #define bigbuf_net (G.bigbuf_net)
148 #define o_verbose (G.o_verbose )
149 #define o_wait (G.o_wait )
151 #define o_interval (G.o_interval)
155 #define INIT_G() do { \
156 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
160 /* Must match getopt32 call! */
169 OPT_l = (1 << 7) * ENABLE_NC_SERVER,
170 OPT_i = (1 << (7+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
171 OPT_o = (1 << (8+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
172 OPT_z = (1 << (9+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
175 #define o_nflag (option_mask32 & OPT_n)
176 #define o_udpmode (option_mask32 & OPT_u)
178 #define o_listen (option_mask32 & OPT_l)
183 #define o_ofile (option_mask32 & OPT_o)
184 #define o_zero (option_mask32 & OPT_z)
190 /* Debug: squirt whatever message and sleep a bit so we can see it go by. */
191 /* Beware: writes to stdOUT... */
193 #define Debug(...) do { printf(__VA_ARGS__); printf("\n"); fflush_all(); sleep(1); } while (0)
195 #define Debug(...) do { } while (0)
198 #define holler_error(...) do { if (o_verbose) bb_error_msg(__VA_ARGS__); } while (0)
199 #define holler_perror(...) do { if (o_verbose) bb_perror_msg(__VA_ARGS__); } while (0)
201 /* catch: no-brainer interrupt handler */
202 static void catch(int sig)
204 if (o_verbose > 1) /* normally we don't care */
205 fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out);
206 fprintf(stderr, "punt!\n");
207 kill_myself_with_sig(sig);
211 static void unarm(void)
213 signal(SIGALRM, SIG_IGN);
217 /* timeout and other signal handling cruft */
218 static void tmtravel(int sig UNUSED_PARAM)
224 /* arm: set the timer. */
225 static void arm(unsigned secs)
227 signal(SIGALRM, tmtravel);
232 find the next newline in a buffer; return inclusive size of that "line",
233 or the entire buffer size, so the caller knows how much to then write().
234 Not distinguishing \n vs \r\n for the nonce; it just works as is... */
235 static unsigned findline(char *buf, unsigned siz)
239 if (!buf) /* various sanity checks... */
244 for (p = buf; x > 0; x--) {
247 x++; /* 'sokay if it points just past the end! */
248 Debug("findline returning %d", x);
253 Debug("findline returning whole thing: %d", siz);
258 fiddle all the file descriptors around, and hand off to another prog. Sort
259 of like a one-off "poor man's inetd". This is the only section of code
260 that would be security-critical, which is why it's ifdefed out by default.
261 Use at your own hairy risk; if you leave shells lying around behind open
262 listening ports you deserve to lose!! */
263 static int doexec(char **proggie) NORETURN;
264 static int doexec(char **proggie)
268 /* dup2(0, 2); - do we *really* want this? NO!
269 * exec'ed prog can do it yourself, if needed */
270 execvp(proggie[0], proggie);
271 bb_perror_msg_and_die("can't execute '%s'", proggie[0]);
274 /* connect_w_timeout:
275 return an fd for one of
276 an open outbound TCP connection, a UDP stub-socket thingie, or
277 an unconnected TCP or UDP socket to listen on.
278 Examines various global o_blah flags to figure out what to do.
279 lad can be NULL, then socket is not bound to any local ip[:port] */
280 static int connect_w_timeout(int fd)
284 /* wrap connect inside a timer, and hit it */
286 if (setjmp(jbuf) == 0) {
287 rr = connect(fd, &themaddr->u.sa, themaddr->len);
289 } else { /* setjmp: connect failed... */
291 errno = ETIMEDOUT; /* fake it */
298 incoming and returns an open connection *from* someplace. If we were
299 given host/port args, any connections from elsewhere are rejected. This
300 in conjunction with local-address binding should limit things nicely... */
301 static void dolisten(void)
306 xlisten(netfd, 1); /* TCP: gotta listen() before we can get */
308 /* Various things that follow temporarily trash bigbuf_net, which might contain
309 a copy of any recvfrom()ed packet, but we'll read() another copy later. */
311 /* I can't believe I have to do all this to get my own goddamn bound address
312 and port number. It should just get filled in during bind() or something.
313 All this is only useful if we didn't say -p for listening, since if we
314 said -p we *know* what port we're listening on. At any rate we won't bother
315 with it all unless we wanted to see it, although listening quietly on a
316 random unknown port is probably not very useful without "netstat". */
319 getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
321 // bb_perror_msg_and_die("getsockname after bind");
322 addr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
323 fprintf(stderr, "listening on %s ...\n", addr);
328 /* UDP is a speeeeecial case -- we have to do I/O *and* get the calling
329 party's particulars all at once, listen() and accept() don't apply.
330 At least in the BSD universe, however, recvfrom/PEEK is enough to tell
331 us something came in, and we can set things up so straight read/write
332 actually does work after all. Yow. YMMV on strange platforms! */
334 /* I'm not completely clear on how this works -- BSD seems to make UDP
335 just magically work in a connect()ed context, but we'll undoubtedly run
336 into systems this deal doesn't work on. For now, we apparently have to
337 issue a connect() on our just-tickled socket so we can write() back.
338 Again, why the fuck doesn't it just get filled in and taken care of?!
339 This hack is anything but optimal. Basically, if you want your listener
340 to also be able to send data back, you need this connect() line, which
341 also has the side effect that now anything from a different source or even a
342 different port on the other end won't show up and will cause ICMP errors.
343 I guess that's what they meant by "connect".
344 Let's try to remember what the "U" is *really* for, eh? */
346 /* If peer address is specified, connect to it */
347 remend.len = LSA_SIZEOF_SA;
350 xconnect(netfd, &themaddr->u.sa, themaddr->len);
352 /* peek first packet and remember peer addr */
353 arm(o_wait); /* might as well timeout this, too */
354 if (setjmp(jbuf) == 0) { /* do timeout for initial connect */
355 /* (*ouraddr) is prefilled with "default" address */
356 /* and here we block... */
357 rr = recv_from_to(netfd, NULL, 0, MSG_PEEK, /*was bigbuf_net, BIGSIZ*/
358 &remend.u.sa, &ouraddr->u.sa, ouraddr->len);
360 bb_perror_msg_and_die("recvfrom");
363 bb_error_msg_and_die("timeout");
364 /* Now we learned *to which IP* peer has connected, and we want to anchor
365 our socket on it, so that our outbound packets will have correct local IP.
366 Unfortunately, bind() on already bound socket will fail now (EINVAL):
367 xbind(netfd, &ouraddr->u.sa, ouraddr->len);
368 Need to read the packet, save data, close this socket and
369 create new one, and bind() it. TODO */
371 xconnect(netfd, &remend.u.sa, ouraddr->len);
374 arm(o_wait); /* wrap this in a timer, too; 0 = forever */
375 if (setjmp(jbuf) == 0) {
377 remend.len = LSA_SIZEOF_SA;
378 rr = accept(netfd, &remend.u.sa, &remend.len);
380 bb_perror_msg_and_die("accept");
382 int sv_port, port, r;
384 sv_port = get_nport(&remend.u.sa); /* save */
385 port = get_nport(&themaddr->u.sa);
387 /* "nc -nl -p LPORT RHOST" (w/o RPORT!):
388 * we should accept any remote port */
389 set_nport(&remend, 0); /* blot out remote port# */
391 r = memcmp(&remend.u.sa, &themaddr->u.sa, remend.len);
392 set_nport(&remend, sv_port); /* restore */
394 /* nc 1.10 bails out instead, and its error message
395 * is not suppressed by o_verbose */
397 char *remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
398 bb_error_msg("connect from wrong ip/port %s ignored", remaddr);
407 bb_error_msg_and_die("timeout");
408 xmove_fd(rr, netfd); /* dump the old socket, here's our new one */
409 /* find out what address the connection was *to* on our end, in case we're
410 doing a listen-on-any on a multihomed machine. This allows one to
411 offer different services via different alias addresses, such as the
412 "virtual web site" hack. */
413 getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
415 // bb_perror_msg_and_die("getsockname after accept");
419 char *lcladdr, *remaddr, *remhostname;
421 #if ENABLE_NC_EXTRA && defined(IP_OPTIONS)
422 /* If we can, look for any IP options. Useful for testing the receiving end of
423 such things, and is a good exercise in dealing with it. We do this before
424 the connect message, to ensure that the connect msg is uniformly the LAST
425 thing to emerge after all the intervening crud. Doesn't work for UDP on
426 any machines I've tested, but feel free to surprise me. */
428 socklen_t x = sizeof(optbuf);
430 rr = getsockopt(netfd, IPPROTO_IP, IP_OPTIONS, optbuf, &x);
431 if (rr >= 0 && x) { /* we've got options, lessee em... */
432 bin2hex(bigbuf_net, optbuf, x);
433 bigbuf_net[2*x] = '\0';
434 fprintf(stderr, "IP options: %s\n", bigbuf_net);
438 /* now check out who it is. We don't care about mismatched DNS names here,
439 but any ADDR and PORT we specified had better fucking well match the caller.
440 Converting from addr to inet_ntoa and back again is a bit of a kludge, but
441 gethostpoop wants a string and there's much gnarlier code out there already,
443 The *real* question is why BFD sockets wasn't designed to allow listens for
444 connections *from* specific hosts/ports, instead of requiring the caller to
445 accept the connection and then reject undesireable ones by closing.
446 In other words, we need a TCP MSG_PEEK. */
447 /* bbox: removed most of it */
448 lcladdr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
449 remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
450 remhostname = o_nflag ? remaddr : xmalloc_sockaddr2host(&remend.u.sa);
451 fprintf(stderr, "connect to %s from %s (%s)\n",
452 lcladdr, remhostname, remaddr);
461 fire a couple of packets at a UDP target port, just to see if it's really
462 there. On BSD kernels, ICMP host/port-unreachable errors get delivered to
463 our socket as ECONNREFUSED write errors. On SV kernels, we lose; we'll have
464 to collect and analyze raw ICMP ourselves a la satan's probe_udp_ports
465 backend. Guess where one could swipe the appropriate code from...
467 Use the time delay between writes if given, otherwise use the "tcp ping"
468 trick for getting the RTT. [I got that idea from pluvius, and warped it.]
469 Return either the original fd, or clean up and return -1. */
471 static int udptest(void)
475 rr = write(netfd, bigbuf_in, 1);
477 bb_perror_msg("udptest first write");
480 sleep(o_wait); // can be interrupted! while (t) nanosleep(&t)?
482 /* use the tcp-ping trick: try connecting to a normally refused port, which
483 causes us to block for the time that SYN gets there and RST gets back.
484 Not completely reliable, but it *does* mostly work. */
485 /* Set a temporary connect timeout, so packet filtration doesnt cause
486 us to hang forever, and hit it */
487 o_wait = 5; /* enough that we'll notice?? */
488 rr = xsocket(ouraddr->u.sa.sa_family, SOCK_STREAM, 0);
489 set_nport(themaddr, htons(SLEAZE_PORT));
490 connect_w_timeout(rr);
491 /* don't need to restore themaddr's port, it's not used anymore */
493 o_wait = 0; /* restore */
496 rr = write(netfd, bigbuf_in, 1);
497 return (rr != 1); /* if rr == 1, return 0 (success) */
504 Hexdump bytes shoveled either way to a running logfile, in the format:
505 D offset - - - - --- 16 bytes --- - - - - # .... ascii .....
506 where "which" sets the direction indicator, D:
507 0 -- sent to network, or ">"
508 1 -- rcvd and printed to stdout, or "<"
509 and "buf" and "n" are data-block and length. If the current block generates
510 a partial line, so be it; we *want* that lockstep indication of who sent
511 what when. Adapted from dgaudet's original example -- but must be ripping
512 *fast*, since we don't want to be too disk-bound... */
514 static void oprint(int direction, unsigned char *p, unsigned bc)
516 unsigned obc; /* current "global" offset */
518 unsigned char *op; /* out hexdump ptr */
519 unsigned char *ap; /* out asc-dump ptr */
520 unsigned char stage[100];
525 obc = wrote_net; /* use the globals! */
526 if (direction == '<')
528 stage[0] = direction;
529 stage[59] = '#'; /* preload separator */
532 do { /* for chunk-o-data ... */
535 /* memset(&stage[bc*3 + 11], ' ', 16*3 - bc*3); */
536 memset(&stage[11], ' ', 16*3);
539 sprintf((char *)&stage[1], " %8.8x ", obc); /* xxx: still slow? */
540 bc -= x; /* fix current count */
541 obc += x; /* fix current offset */
542 op = &stage[11]; /* where hex starts */
543 ap = &stage[61]; /* where ascii starts */
545 do { /* for line of dump, however long ... */
546 *op++ = 0x20 | bb_hexdigits_upcase[*p >> 4];
547 *op++ = 0x20 | bb_hexdigits_upcase[*p & 0x0f];
549 if ((*p > 31) && (*p < 127))
550 *ap = *p; /* printing */
552 *ap = '.'; /* nonprinting, loose def */
556 *ap++ = '\n'; /* finish the line */
557 xwrite(ofd, stage, ap - stage);
561 void oprint(int direction, unsigned char *p, unsigned bc);
565 handle stdin/stdout/network I/O. Bwahaha!! -- the select loop from hell.
566 In this instance, return what might become our exit status. */
567 static int readwrite(void)
570 char *zp = zp; /* gcc */ /* stdin buf ptr */
571 char *np = np; /* net-in buf ptr */
574 unsigned netretry; /* net-read retry counter */
575 unsigned wretry; /* net-write sanity counter */
576 unsigned wfirst; /* one-shot flag to skip first net read */
578 /* if you don't have all this FD_* macro hair in sys/types.h, you'll have to
579 either find it or do your own bit-bashing: *ding1 |= (1 << fd), etc... */
580 FD_SET(netfd, &ding1); /* global: the net is open */
585 sleep(o_interval); /* pause *before* sending stuff, too */
587 errno = 0; /* clear from sleep, close, whatever */
588 /* and now the big ol' select shoveling loop ... */
589 while (FD_ISSET(netfd, &ding1)) { /* i.e. till the *net* closes! */
590 wretry = 8200; /* more than we'll ever hafta write */
591 if (wfirst) { /* any saved stdin buffer? */
592 wfirst = 0; /* clear flag for the duration */
593 goto shovel; /* and go handle it first */
595 ding2 = ding1; /* FD_COPY ain't portable... */
596 /* some systems, notably linux, crap into their select timers on return, so
597 we create a expendable copy and give *that* to select. */
599 struct timeval tmp_timer;
600 tmp_timer.tv_sec = o_wait;
601 tmp_timer.tv_usec = 0;
602 /* highest possible fd is netfd (3) */
603 rr = select(netfd+1, &ding2, NULL, NULL, &tmp_timer);
605 rr = select(netfd+1, &ding2, NULL, NULL, NULL);
606 if (rr < 0 && errno != EINTR) { /* might have gotten ^Zed, etc */
607 holler_perror("select");
611 /* if we have a timeout AND stdin is closed AND we haven't heard anything
612 from the net during that time, assume it's dead and close it too. */
614 if (!FD_ISSET(STDIN_FILENO, &ding1))
615 netretry--; /* we actually try a coupla times. */
617 if (o_verbose > 1) /* normally we don't care */
618 fprintf(stderr, "net timeout\n");
620 return 0; /* not an error! */
622 } /* select timeout */
623 /* xxx: should we check the exception fds too? The read fds seem to give
624 us the right info, and none of the examples I found bothered. */
626 /* Ding!! Something arrived, go check all the incoming hoppers, net first */
627 if (FD_ISSET(netfd, &ding2)) { /* net: ding! */
628 rr = read(netfd, bigbuf_net, BIGSIZ);
630 if (rr < 0 && o_verbose > 1) {
631 /* nc 1.10 doesn't do this */
632 bb_perror_msg("net read");
634 FD_CLR(netfd, &ding1); /* net closed, we'll finish up... */
635 rzleft = 0; /* can't write anymore: broken pipe */
640 Debug("got %d from the net, errno %d", rr, errno);
643 /* if we're in "slowly" mode there's probably still stuff in the stdin
644 buffer, so don't read unless we really need MORE INPUT! MORE INPUT! */
648 /* okay, suck more stdin */
649 if (FD_ISSET(STDIN_FILENO, &ding2)) { /* stdin: ding! */
650 rr = read(STDIN_FILENO, bigbuf_in, BIGSIZ);
651 /* Considered making reads here smaller for UDP mode, but 8192-byte
652 mobygrams are kinda fun and exercise the reassembler. */
653 if (rr <= 0) { /* at end, or fukt, or ... */
654 FD_CLR(STDIN_FILENO, &ding1); /* disable and close stdin */
656 // Does it make sense to shutdown(net_fd, SHUT_WR)
657 // to let other side know that we won't write anything anymore?
658 // (and what about keeping compat if we do that?)
665 /* now that we've dingdonged all our thingdings, send off the results.
666 Geez, why does this look an awful lot like the big loop in "rsh"? ...
667 not sure if the order of this matters, but write net -> stdout first. */
669 /* sanity check. Works because they're both unsigned... */
670 if ((rzleft > 8200) || (rnleft > 8200)) {
671 holler_error("bogus buffers: %u, %u", rzleft, rnleft);
674 /* net write retries sometimes happen on UDP connections */
675 if (!wretry) { /* is something hung? */
676 holler_error("too many output retries");
680 rr = write(STDOUT_FILENO, np, rnleft);
682 if (o_ofile) /* log the stdout */
683 oprint('<', (unsigned char *)np, rr);
684 np += rr; /* fix up ptrs and whatnot */
685 rnleft -= rr; /* will get sanity-checked above */
686 wrote_out += rr; /* global count */
688 Debug("wrote %d to stdout, errno %d", rr, errno);
691 if (o_interval) /* in "slowly" mode ?? */
692 rr = findline(zp, rzleft);
695 rr = write(netfd, zp, rr); /* one line, or the whole buffer */
697 if (o_ofile) /* log what got sent */
698 oprint('>', (unsigned char *)zp, rr);
701 wrote_net += rr; /* global count */
703 Debug("wrote %d to net, errno %d", rr, errno);
705 if (o_interval) { /* cycle between slow lines, or ... */
707 errno = 0; /* clear from sleep */
708 continue; /* ...with hairy select loop... */
710 if ((rzleft) || (rnleft)) { /* shovel that shit till they ain't */
711 wretry--; /* none left, and get another load */
714 } /* while ding1:netfd is open */
716 /* XXX: maybe want a more graceful shutdown() here, or screw around with
717 linger times?? I suspect that I don't need to since I'm always doing
718 blocking reads and writes and my own manual "last ditch" efforts to read
719 the net again after a timeout. I haven't seen any screwups yet, but it's
720 not like my test network is particularly busy... */
725 /* main: now we pull it all together... */
726 int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
727 int nc_main(int argc UNUSED_PARAM, char **argv)
730 IF_NC_EXTRA(char *str_i, *str_o;)
731 char *themdotted = themdotted; /* gcc */
734 unsigned o_lport = 0;
738 /* catch a signal or two for cleanup */
744 /* and suppress others... */
749 + (1 << SIGPIPE) /* important! */
754 if (strcmp(*proggie, "-e") == 0) {
763 // -g -G -t -r deleted, unimplemented -a deleted too
764 opt_complementary = "?2:vv:w+"; /* max 2 params; -v is a counter; -w N */
765 getopt32(argv, "hnp:s:uvw:" IF_NC_SERVER("l")
766 IF_NC_EXTRA("i:o:z"),
767 &str_p, &str_s, &o_wait
768 IF_NC_EXTRA(, &str_i, &str_o, &o_verbose));
771 if (option_mask32 & OPT_i) /* line-interval time */
772 o_interval = xatou_range(str_i, 1, 0xffff);
774 //if (option_mask32 & OPT_l) /* listen mode */
775 //if (option_mask32 & OPT_n) /* numeric-only, no DNS lookups */
776 //if (option_mask32 & OPT_o) /* hexdump log */
777 if (option_mask32 & OPT_p) { /* local source port */
778 o_lport = bb_lookup_port(str_p, o_udpmode ? "udp" : "tcp", 0);
780 bb_error_msg_and_die("bad local port '%s'", str_p);
782 //if (option_mask32 & OPT_r) /* randomize various things */
783 //if (option_mask32 & OPT_u) /* use UDP */
784 //if (option_mask32 & OPT_v) /* verbose */
785 //if (option_mask32 & OPT_w) /* wait time */
786 //if (option_mask32 & OPT_z) /* little or no data xfer */
788 /* We manage our fd's so that they are never 0,1,2 */
789 /*bb_sanitize_stdio(); - not needed */
792 themaddr = xhost2sockaddr(argv[0],
794 ? bb_lookup_port(argv[1], o_udpmode ? "udp" : "tcp", 0)
798 /* create & bind network socket */
799 x = (o_udpmode ? SOCK_DGRAM : SOCK_STREAM);
800 if (option_mask32 & OPT_s) { /* local address */
801 /* if o_lport is still 0, then we will use random port */
802 ouraddr = xhost2sockaddr(str_s, o_lport);
804 /* prevent spurious "UDP listen needs !0 port" */
805 o_lport = get_nport(ouraddr);
806 o_lport = ntohs(o_lport);
808 x = xsocket(ouraddr->u.sa.sa_family, x, 0);
810 /* We try IPv6, then IPv4, unless addr family is
811 * implicitly set by way of remote addr/port spec */
812 x = xsocket_type(&ouraddr,
813 (themaddr ? themaddr->u.sa.sa_family : AF_UNSPEC),
816 set_nport(ouraddr, htons(o_lport));
819 setsockopt_reuseaddr(netfd);
821 socket_want_pktinfo(netfd);
822 if (!ENABLE_FEATURE_UNIX_LOCAL
824 || ouraddr->u.sa.sa_family != AF_UNIX
826 xbind(netfd, &ouraddr->u.sa, ouraddr->len);
829 setsockopt(netfd, SOL_SOCKET, SO_RCVBUF, &o_rcvbuf, sizeof o_rcvbuf);
830 setsockopt(netfd, SOL_SOCKET, SO_SNDBUF, &o_sndbuf, sizeof o_sndbuf);
834 if (OPT_l && (option_mask32 & (OPT_u|OPT_l)) == (OPT_u|OPT_l)) {
835 /* apparently UDP can listen ON "port 0",
836 but that's not useful */
838 bb_error_msg_and_die("UDP listen needs nonzero -p port");
842 FD_SET(STDIN_FILENO, &ding1); /* stdin *is* initially open */
844 close(0); /* won't need stdin */
845 option_mask32 &= ~OPT_o; /* -o with -e is meaningless! */
849 xmove_fd(xopen(str_o, O_WRONLY|O_CREAT|O_TRUNC), ofd);
854 /* dolisten does its own connect reporting */
855 if (proggie) /* -e given? */
857 x = readwrite(); /* it even works with UDP! */
859 /* Outbound connects. Now we're more picky about args... */
861 bb_error_msg_and_die("no destination");
865 themdotted = xmalloc_sockaddr2dotted(&themaddr->u.sa);
867 x = connect_w_timeout(netfd);
868 if (o_zero && x == 0 && o_udpmode) /* if UDP scanning... */
870 if (x == 0) { /* Yow, are we OPEN YET?! */
872 fprintf(stderr, "%s (%s) open\n", argv[0], themdotted);
873 if (proggie) /* exec is valid for outbound, too */
877 } else { /* connect or udptest wasn't successful */
878 x = 1; /* exit status */
879 /* if we're scanning at a "one -v" verbosity level, don't print refusals.
880 Give it another -v if you want to see everything. */
881 if (o_verbose > 1 || (o_verbose && errno != ECONNREFUSED))
882 bb_perror_msg("%s (%s)", argv[0], themdotted);
885 if (o_verbose > 1) /* normally we don't care */
886 fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out);