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"
63 //usage: " -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 BB_EXECVP_or_die(proggie);
273 /* connect_w_timeout:
274 return an fd for one of
275 an open outbound TCP connection, a UDP stub-socket thingie, or
276 an unconnected TCP or UDP socket to listen on.
277 Examines various global o_blah flags to figure out what to do.
278 lad can be NULL, then socket is not bound to any local ip[:port] */
279 static int connect_w_timeout(int fd)
283 /* wrap connect inside a timer, and hit it */
285 if (setjmp(jbuf) == 0) {
286 rr = connect(fd, &themaddr->u.sa, themaddr->len);
288 } else { /* setjmp: connect failed... */
290 errno = ETIMEDOUT; /* fake it */
297 incoming and returns an open connection *from* someplace. If we were
298 given host/port args, any connections from elsewhere are rejected. This
299 in conjunction with local-address binding should limit things nicely... */
300 static void dolisten(void)
305 xlisten(netfd, 1); /* TCP: gotta listen() before we can get */
307 /* Various things that follow temporarily trash bigbuf_net, which might contain
308 a copy of any recvfrom()ed packet, but we'll read() another copy later. */
310 /* I can't believe I have to do all this to get my own goddamn bound address
311 and port number. It should just get filled in during bind() or something.
312 All this is only useful if we didn't say -p for listening, since if we
313 said -p we *know* what port we're listening on. At any rate we won't bother
314 with it all unless we wanted to see it, although listening quietly on a
315 random unknown port is probably not very useful without "netstat". */
318 getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
320 // bb_perror_msg_and_die("getsockname after bind");
321 addr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
322 fprintf(stderr, "listening on %s ...\n", addr);
327 /* UDP is a speeeeecial case -- we have to do I/O *and* get the calling
328 party's particulars all at once, listen() and accept() don't apply.
329 At least in the BSD universe, however, recvfrom/PEEK is enough to tell
330 us something came in, and we can set things up so straight read/write
331 actually does work after all. Yow. YMMV on strange platforms! */
333 /* I'm not completely clear on how this works -- BSD seems to make UDP
334 just magically work in a connect()ed context, but we'll undoubtedly run
335 into systems this deal doesn't work on. For now, we apparently have to
336 issue a connect() on our just-tickled socket so we can write() back.
337 Again, why the fuck doesn't it just get filled in and taken care of?!
338 This hack is anything but optimal. Basically, if you want your listener
339 to also be able to send data back, you need this connect() line, which
340 also has the side effect that now anything from a different source or even a
341 different port on the other end won't show up and will cause ICMP errors.
342 I guess that's what they meant by "connect".
343 Let's try to remember what the "U" is *really* for, eh? */
345 /* If peer address is specified, connect to it */
346 remend.len = LSA_SIZEOF_SA;
349 xconnect(netfd, &themaddr->u.sa, themaddr->len);
351 /* peek first packet and remember peer addr */
352 arm(o_wait); /* might as well timeout this, too */
353 if (setjmp(jbuf) == 0) { /* do timeout for initial connect */
354 /* (*ouraddr) is prefilled with "default" address */
355 /* and here we block... */
356 rr = recv_from_to(netfd, NULL, 0, MSG_PEEK, /*was bigbuf_net, BIGSIZ*/
357 &remend.u.sa, &ouraddr->u.sa, ouraddr->len);
359 bb_perror_msg_and_die("recvfrom");
362 bb_error_msg_and_die("timeout");
363 /* Now we learned *to which IP* peer has connected, and we want to anchor
364 our socket on it, so that our outbound packets will have correct local IP.
365 Unfortunately, bind() on already bound socket will fail now (EINVAL):
366 xbind(netfd, &ouraddr->u.sa, ouraddr->len);
367 Need to read the packet, save data, close this socket and
368 create new one, and bind() it. TODO */
370 xconnect(netfd, &remend.u.sa, ouraddr->len);
373 arm(o_wait); /* wrap this in a timer, too; 0 = forever */
374 if (setjmp(jbuf) == 0) {
376 remend.len = LSA_SIZEOF_SA;
377 rr = accept(netfd, &remend.u.sa, &remend.len);
379 bb_perror_msg_and_die("accept");
381 int sv_port, port, r;
383 sv_port = get_nport(&remend.u.sa); /* save */
384 port = get_nport(&themaddr->u.sa);
386 /* "nc -nl -p LPORT RHOST" (w/o RPORT!):
387 * we should accept any remote port */
388 set_nport(&remend.u.sa, 0); /* blot out remote port# */
390 r = memcmp(&remend.u.sa, &themaddr->u.sa, remend.len);
391 set_nport(&remend.u.sa, sv_port); /* restore */
393 /* nc 1.10 bails out instead, and its error message
394 * is not suppressed by o_verbose */
396 char *remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
397 bb_error_msg("connect from wrong ip/port %s ignored", remaddr);
406 bb_error_msg_and_die("timeout");
407 xmove_fd(rr, netfd); /* dump the old socket, here's our new one */
408 /* find out what address the connection was *to* on our end, in case we're
409 doing a listen-on-any on a multihomed machine. This allows one to
410 offer different services via different alias addresses, such as the
411 "virtual web site" hack. */
412 getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
414 // bb_perror_msg_and_die("getsockname after accept");
418 char *lcladdr, *remaddr, *remhostname;
420 #if ENABLE_NC_EXTRA && defined(IP_OPTIONS)
421 /* If we can, look for any IP options. Useful for testing the receiving end of
422 such things, and is a good exercise in dealing with it. We do this before
423 the connect message, to ensure that the connect msg is uniformly the LAST
424 thing to emerge after all the intervening crud. Doesn't work for UDP on
425 any machines I've tested, but feel free to surprise me. */
427 socklen_t x = sizeof(optbuf);
429 rr = getsockopt(netfd, IPPROTO_IP, IP_OPTIONS, optbuf, &x);
430 if (rr >= 0 && x) { /* we've got options, lessee em... */
431 *bin2hex(bigbuf_net, optbuf, x) = '\0';
432 fprintf(stderr, "IP options: %s\n", bigbuf_net);
436 /* now check out who it is. We don't care about mismatched DNS names here,
437 but any ADDR and PORT we specified had better fucking well match the caller.
438 Converting from addr to inet_ntoa and back again is a bit of a kludge, but
439 gethostpoop wants a string and there's much gnarlier code out there already,
441 The *real* question is why BFD sockets wasn't designed to allow listens for
442 connections *from* specific hosts/ports, instead of requiring the caller to
443 accept the connection and then reject undesireable ones by closing.
444 In other words, we need a TCP MSG_PEEK. */
445 /* bbox: removed most of it */
446 lcladdr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
447 remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
448 remhostname = o_nflag ? remaddr : xmalloc_sockaddr2host(&remend.u.sa);
449 fprintf(stderr, "connect to %s from %s (%s)\n",
450 lcladdr, remhostname, remaddr);
459 fire a couple of packets at a UDP target port, just to see if it's really
460 there. On BSD kernels, ICMP host/port-unreachable errors get delivered to
461 our socket as ECONNREFUSED write errors. On SV kernels, we lose; we'll have
462 to collect and analyze raw ICMP ourselves a la satan's probe_udp_ports
463 backend. Guess where one could swipe the appropriate code from...
465 Use the time delay between writes if given, otherwise use the "tcp ping"
466 trick for getting the RTT. [I got that idea from pluvius, and warped it.]
467 Return either the original fd, or clean up and return -1. */
469 static int udptest(void)
473 rr = write(netfd, bigbuf_in, 1);
475 bb_perror_msg("udptest first write");
478 sleep(o_wait); // can be interrupted! while (t) nanosleep(&t)?
480 /* use the tcp-ping trick: try connecting to a normally refused port, which
481 causes us to block for the time that SYN gets there and RST gets back.
482 Not completely reliable, but it *does* mostly work. */
483 /* Set a temporary connect timeout, so packet filtration doesnt cause
484 us to hang forever, and hit it */
485 o_wait = 5; /* enough that we'll notice?? */
486 rr = xsocket(ouraddr->u.sa.sa_family, SOCK_STREAM, 0);
487 set_nport(&themaddr->u.sa, htons(SLEAZE_PORT));
488 connect_w_timeout(rr);
489 /* don't need to restore themaddr's port, it's not used anymore */
491 o_wait = 0; /* restore */
494 rr = write(netfd, bigbuf_in, 1);
495 return (rr != 1); /* if rr == 1, return 0 (success) */
502 Hexdump bytes shoveled either way to a running logfile, in the format:
503 D offset - - - - --- 16 bytes --- - - - - # .... ascii .....
504 where "which" sets the direction indicator, D:
505 0 -- sent to network, or ">"
506 1 -- rcvd and printed to stdout, or "<"
507 and "buf" and "n" are data-block and length. If the current block generates
508 a partial line, so be it; we *want* that lockstep indication of who sent
509 what when. Adapted from dgaudet's original example -- but must be ripping
510 *fast*, since we don't want to be too disk-bound... */
512 static void oprint(int direction, unsigned char *p, unsigned bc)
514 unsigned obc; /* current "global" offset */
516 unsigned char *op; /* out hexdump ptr */
517 unsigned char *ap; /* out asc-dump ptr */
518 unsigned char stage[100];
523 obc = wrote_net; /* use the globals! */
524 if (direction == '<')
526 stage[0] = direction;
527 stage[59] = '#'; /* preload separator */
530 do { /* for chunk-o-data ... */
533 /* memset(&stage[bc*3 + 11], ' ', 16*3 - bc*3); */
534 memset(&stage[11], ' ', 16*3);
537 sprintf((char *)&stage[1], " %8.8x ", obc); /* xxx: still slow? */
538 bc -= x; /* fix current count */
539 obc += x; /* fix current offset */
540 op = &stage[11]; /* where hex starts */
541 ap = &stage[61]; /* where ascii starts */
543 do { /* for line of dump, however long ... */
544 *op++ = 0x20 | bb_hexdigits_upcase[*p >> 4];
545 *op++ = 0x20 | bb_hexdigits_upcase[*p & 0x0f];
547 if ((*p > 31) && (*p < 127))
548 *ap = *p; /* printing */
550 *ap = '.'; /* nonprinting, loose def */
554 *ap++ = '\n'; /* finish the line */
555 xwrite(ofd, stage, ap - stage);
559 void oprint(int direction, unsigned char *p, unsigned bc);
563 handle stdin/stdout/network I/O. Bwahaha!! -- the select loop from hell.
564 In this instance, return what might become our exit status. */
565 static int readwrite(void)
568 char *zp = zp; /* gcc */ /* stdin buf ptr */
569 char *np = np; /* net-in buf ptr */
572 unsigned netretry; /* net-read retry counter */
573 unsigned wretry; /* net-write sanity counter */
574 unsigned wfirst; /* one-shot flag to skip first net read */
576 /* if you don't have all this FD_* macro hair in sys/types.h, you'll have to
577 either find it or do your own bit-bashing: *ding1 |= (1 << fd), etc... */
578 FD_SET(netfd, &ding1); /* global: the net is open */
583 sleep(o_interval); /* pause *before* sending stuff, too */
585 errno = 0; /* clear from sleep, close, whatever */
586 /* and now the big ol' select shoveling loop ... */
587 while (FD_ISSET(netfd, &ding1)) { /* i.e. till the *net* closes! */
588 wretry = 8200; /* more than we'll ever hafta write */
589 if (wfirst) { /* any saved stdin buffer? */
590 wfirst = 0; /* clear flag for the duration */
591 goto shovel; /* and go handle it first */
593 ding2 = ding1; /* FD_COPY ain't portable... */
594 /* some systems, notably linux, crap into their select timers on return, so
595 we create a expendable copy and give *that* to select. */
597 struct timeval tmp_timer;
598 tmp_timer.tv_sec = o_wait;
599 tmp_timer.tv_usec = 0;
600 /* highest possible fd is netfd (3) */
601 rr = select(netfd+1, &ding2, NULL, NULL, &tmp_timer);
603 rr = select(netfd+1, &ding2, NULL, NULL, NULL);
604 if (rr < 0 && errno != EINTR) { /* might have gotten ^Zed, etc */
605 holler_perror("select");
609 /* if we have a timeout AND stdin is closed AND we haven't heard anything
610 from the net during that time, assume it's dead and close it too. */
612 if (!FD_ISSET(STDIN_FILENO, &ding1))
613 netretry--; /* we actually try a coupla times. */
615 if (o_verbose > 1) /* normally we don't care */
616 fprintf(stderr, "net timeout\n");
618 return 0; /* not an error! */
620 } /* select timeout */
621 /* xxx: should we check the exception fds too? The read fds seem to give
622 us the right info, and none of the examples I found bothered. */
624 /* Ding!! Something arrived, go check all the incoming hoppers, net first */
625 if (FD_ISSET(netfd, &ding2)) { /* net: ding! */
626 rr = read(netfd, bigbuf_net, BIGSIZ);
628 if (rr < 0 && o_verbose > 1) {
629 /* nc 1.10 doesn't do this */
630 bb_perror_msg("net read");
632 FD_CLR(netfd, &ding1); /* net closed, we'll finish up... */
633 rzleft = 0; /* can't write anymore: broken pipe */
638 Debug("got %d from the net, errno %d", rr, errno);
641 /* if we're in "slowly" mode there's probably still stuff in the stdin
642 buffer, so don't read unless we really need MORE INPUT! MORE INPUT! */
646 /* okay, suck more stdin */
647 if (FD_ISSET(STDIN_FILENO, &ding2)) { /* stdin: ding! */
648 rr = read(STDIN_FILENO, bigbuf_in, BIGSIZ);
649 /* Considered making reads here smaller for UDP mode, but 8192-byte
650 mobygrams are kinda fun and exercise the reassembler. */
651 if (rr <= 0) { /* at end, or fukt, or ... */
652 FD_CLR(STDIN_FILENO, &ding1); /* disable and close stdin */
654 // Does it make sense to shutdown(net_fd, SHUT_WR)
655 // to let other side know that we won't write anything anymore?
656 // (and what about keeping compat if we do that?)
663 /* now that we've dingdonged all our thingdings, send off the results.
664 Geez, why does this look an awful lot like the big loop in "rsh"? ...
665 not sure if the order of this matters, but write net -> stdout first. */
667 /* sanity check. Works because they're both unsigned... */
668 if ((rzleft > 8200) || (rnleft > 8200)) {
669 holler_error("bogus buffers: %u, %u", rzleft, rnleft);
672 /* net write retries sometimes happen on UDP connections */
673 if (!wretry) { /* is something hung? */
674 holler_error("too many output retries");
678 rr = write(STDOUT_FILENO, np, rnleft);
680 if (o_ofile) /* log the stdout */
681 oprint('<', (unsigned char *)np, rr);
682 np += rr; /* fix up ptrs and whatnot */
683 rnleft -= rr; /* will get sanity-checked above */
684 wrote_out += rr; /* global count */
686 Debug("wrote %d to stdout, errno %d", rr, errno);
689 if (o_interval) /* in "slowly" mode ?? */
690 rr = findline(zp, rzleft);
693 rr = write(netfd, zp, rr); /* one line, or the whole buffer */
695 if (o_ofile) /* log what got sent */
696 oprint('>', (unsigned char *)zp, rr);
699 wrote_net += rr; /* global count */
701 Debug("wrote %d to net, errno %d", rr, errno);
703 if (o_interval) { /* cycle between slow lines, or ... */
705 errno = 0; /* clear from sleep */
706 continue; /* ...with hairy select loop... */
708 if ((rzleft) || (rnleft)) { /* shovel that shit till they ain't */
709 wretry--; /* none left, and get another load */
712 } /* while ding1:netfd is open */
714 /* XXX: maybe want a more graceful shutdown() here, or screw around with
715 linger times?? I suspect that I don't need to since I'm always doing
716 blocking reads and writes and my own manual "last ditch" efforts to read
717 the net again after a timeout. I haven't seen any screwups yet, but it's
718 not like my test network is particularly busy... */
723 /* main: now we pull it all together... */
724 int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
725 int nc_main(int argc UNUSED_PARAM, char **argv)
728 IF_NC_EXTRA(char *str_i, *str_o;)
729 char *themdotted = themdotted; /* gcc */
732 unsigned o_lport = 0;
736 /* catch a signal or two for cleanup */
742 /* and suppress others... */
747 + (1 << SIGPIPE) /* important! */
752 if (strcmp(*proggie, "-e") == 0) {
761 // -g -G -t -r deleted, unimplemented -a deleted too
762 opt_complementary = "?2:vv:w+"; /* max 2 params; -v is a counter; -w N */
763 getopt32(argv, "hnp:s:uvw:" IF_NC_SERVER("l")
764 IF_NC_EXTRA("i:o:z"),
765 &str_p, &str_s, &o_wait
766 IF_NC_EXTRA(, &str_i, &str_o), &o_verbose);
769 if (option_mask32 & OPT_i) /* line-interval time */
770 o_interval = xatou_range(str_i, 1, 0xffff);
772 //if (option_mask32 & OPT_l) /* listen mode */
773 //if (option_mask32 & OPT_n) /* numeric-only, no DNS lookups */
774 //if (option_mask32 & OPT_o) /* hexdump log */
775 if (option_mask32 & OPT_p) { /* local source port */
776 o_lport = bb_lookup_port(str_p, o_udpmode ? "udp" : "tcp", 0);
778 bb_error_msg_and_die("bad local port '%s'", str_p);
780 //if (option_mask32 & OPT_r) /* randomize various things */
781 //if (option_mask32 & OPT_u) /* use UDP */
782 //if (option_mask32 & OPT_v) /* verbose */
783 //if (option_mask32 & OPT_w) /* wait time */
784 //if (option_mask32 & OPT_z) /* little or no data xfer */
786 /* We manage our fd's so that they are never 0,1,2 */
787 /*bb_sanitize_stdio(); - not needed */
790 themaddr = xhost2sockaddr(argv[0],
792 ? bb_lookup_port(argv[1], o_udpmode ? "udp" : "tcp", 0)
796 /* create & bind network socket */
797 x = (o_udpmode ? SOCK_DGRAM : SOCK_STREAM);
798 if (option_mask32 & OPT_s) { /* local address */
799 /* if o_lport is still 0, then we will use random port */
800 ouraddr = xhost2sockaddr(str_s, o_lport);
802 /* prevent spurious "UDP listen needs !0 port" */
803 o_lport = get_nport(ouraddr);
804 o_lport = ntohs(o_lport);
806 x = xsocket(ouraddr->u.sa.sa_family, x, 0);
808 /* We try IPv6, then IPv4, unless addr family is
809 * implicitly set by way of remote addr/port spec */
810 x = xsocket_type(&ouraddr,
811 (themaddr ? themaddr->u.sa.sa_family : AF_UNSPEC),
814 set_nport(&ouraddr->u.sa, htons(o_lport));
817 setsockopt_reuseaddr(netfd);
819 socket_want_pktinfo(netfd);
820 if (!ENABLE_FEATURE_UNIX_LOCAL
822 || ouraddr->u.sa.sa_family != AF_UNIX
824 xbind(netfd, &ouraddr->u.sa, ouraddr->len);
827 setsockopt(netfd, SOL_SOCKET, SO_RCVBUF, &o_rcvbuf, sizeof o_rcvbuf);
828 setsockopt(netfd, SOL_SOCKET, SO_SNDBUF, &o_sndbuf, sizeof o_sndbuf);
832 if (OPT_l && (option_mask32 & (OPT_u|OPT_l)) == (OPT_u|OPT_l)) {
833 /* apparently UDP can listen ON "port 0",
834 but that's not useful */
836 bb_error_msg_and_die("UDP listen needs nonzero -p port");
840 FD_SET(STDIN_FILENO, &ding1); /* stdin *is* initially open */
842 close(0); /* won't need stdin */
843 option_mask32 &= ~OPT_o; /* -o with -e is meaningless! */
847 xmove_fd(xopen(str_o, O_WRONLY|O_CREAT|O_TRUNC), ofd);
852 /* dolisten does its own connect reporting */
853 if (proggie) /* -e given? */
855 x = readwrite(); /* it even works with UDP! */
857 /* Outbound connects. Now we're more picky about args... */
863 themdotted = xmalloc_sockaddr2dotted(&themaddr->u.sa);
865 x = connect_w_timeout(netfd);
866 if (o_zero && x == 0 && o_udpmode) /* if UDP scanning... */
868 if (x == 0) { /* Yow, are we OPEN YET?! */
870 fprintf(stderr, "%s (%s) open\n", argv[0], themdotted);
871 if (proggie) /* exec is valid for outbound, too */
875 } else { /* connect or udptest wasn't successful */
876 x = 1; /* exit status */
877 /* if we're scanning at a "one -v" verbosity level, don't print refusals.
878 Give it another -v if you want to see everything. */
879 if (o_verbose > 1 || (o_verbose && errno != ECONNREFUSED))
880 bb_perror_msg("%s (%s)", argv[0], themdotted);
883 if (o_verbose > 1) /* normally we don't care */
884 fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out);