| /* Based on netcat 1.10 RELEASE 960320 written by hobbit@avian.org. |
| * Released into public domain by the author. |
| * |
| * Copyright (C) 2007 Denys Vlasenko. |
| * |
| * Licensed under GPLv2, see file LICENSE in this source tree. |
| */ |
| |
| /* Author's comments from nc 1.10: |
| * ===================== |
| * Netcat is entirely my own creation, although plenty of other code was used as |
| * examples. It is freely given away to the Internet community in the hope that |
| * it will be useful, with no restrictions except giving credit where it is due. |
| * No GPLs, Berkeley copyrights or any of that nonsense. The author assumes NO |
| * responsibility for how anyone uses it. If netcat makes you rich somehow and |
| * you're feeling generous, mail me a check. If you are affiliated in any way |
| * with Microsoft Network, get a life. Always ski in control. Comments, |
| * questions, and patches to hobbit@avian.org. |
| * ... |
| * Netcat and the associated package is a product of Avian Research, and is freely |
| * available in full source form with no restrictions save an obligation to give |
| * credit where due. |
| * ... |
| * A damn useful little "backend" utility begun 950915 or thereabouts, |
| * as *Hobbit*'s first real stab at some sockets programming. Something that |
| * should have and indeed may have existed ten years ago, but never became a |
| * standard Unix utility. IMHO, "nc" could take its place right next to cat, |
| * cp, rm, mv, dd, ls, and all those other cryptic and Unix-like things. |
| * ===================== |
| * |
| * Much of author's comments are still retained in the code. |
| * |
| * Functionality removed (rationale): |
| * - miltiple-port ranges, randomized port scanning (use nmap) |
| * - telnet support (use telnet) |
| * - source routing |
| * - multiple DNS checks |
| * Functionalty which is different from nc 1.10: |
| * - PROG in '-e PROG' can have ARGS (and options). |
| * Because of this -e option must be last. |
| //TODO: remove -e incompatibility? |
| * - we don't redirect stderr to the network socket for the -e PROG. |
| * (PROG can do it itself if needed, but sometimes it is NOT wanted!) |
| * - numeric addresses are printed in (), not [] (IPv6 looks better), |
| * port numbers are inside (): (1.2.3.4:5678) |
| * - network read errors are reported on verbose levels > 1 |
| * (nc 1.10 treats them as EOF) |
| * - TCP connects from wrong ip/ports (if peer ip:port is specified |
| * on the command line, but accept() says that it came from different addr) |
| * are closed, but we don't exit - we continue to listen/accept. |
| * Since bbox 1.22: |
| * - nc exits when _both_ stdin and network are closed. |
| * This makes these two commands: |
| * echo "Yes" | nc 127.0.0.1 1234 |
| * echo "no" | nc -lp 1234 |
| * exchange their data _and exit_ instead of being stuck. |
| */ |
| |
| /* done in nc.c: #include "libbb.h" */ |
| |
| //usage:#if ENABLE_NC_110_COMPAT |
| //usage: |
| //usage:#define nc_trivial_usage |
| //usage: "[OPTIONS] HOST PORT - connect" |
| //usage: IF_NC_SERVER("\n" |
| //usage: "nc [OPTIONS] -l -p PORT [HOST] [PORT] - listen" |
| //usage: ) |
| //usage:#define nc_full_usage "\n\n" |
| //usage: " -e PROG Run PROG after connect (must be last)" |
| //usage: IF_NC_SERVER( |
| //usage: "\n -l Listen mode, for inbound connects" |
| //usage: "\n -lk With -e, provides persistent server" |
| /* -ll does the same as -lk, but its our extension, while -k is BSD'd, |
| * presumably more widely known. Therefore we advertise it, not -ll. |
| * I would like to drop -ll support, but our "small" nc supports it, |
| * and Rob uses it. |
| */ |
| //usage: ) |
| //usage: "\n -p PORT Local port" |
| //usage: "\n -s ADDR Local address" |
| //usage: "\n -w SEC Timeout for connects and final net reads" |
| //usage: IF_NC_EXTRA( |
| //usage: "\n -i SEC Delay interval for lines sent" /* ", ports scanned" */ |
| //usage: ) |
| //usage: "\n -n Don't do DNS resolution" |
| //usage: "\n -u UDP mode" |
| //usage: "\n -v Verbose" |
| //usage: IF_NC_EXTRA( |
| //usage: "\n -o FILE Hex dump traffic" |
| //usage: "\n -z Zero-I/O mode (scanning)" |
| //usage: ) |
| //usage:#endif |
| |
| /* "\n -r Randomize local and remote ports" */ |
| /* "\n -g gateway Source-routing hop point[s], up to 8" */ |
| /* "\n -G num Source-routing pointer: 4, 8, 12, ..." */ |
| /* "\nport numbers can be individual or ranges: lo-hi [inclusive]" */ |
| |
| /* -e PROG can take ARGS too: "nc ... -e ls -l", but we don't document it |
| * in help text: nc 1.10 does not allow that. We don't want to entice |
| * users to use this incompatibility */ |
| |
| enum { |
| SLEAZE_PORT = 31337, /* for UDP-scan RTT trick, change if ya want */ |
| BIGSIZ = 8192, /* big buffers */ |
| |
| netfd = 3, |
| ofd = 4, |
| }; |
| |
| struct globals { |
| /* global cmd flags: */ |
| unsigned o_verbose; |
| unsigned o_wait; |
| #if ENABLE_NC_EXTRA |
| unsigned o_interval; |
| #endif |
| |
| /*int netfd;*/ |
| /*int ofd;*/ /* hexdump output fd */ |
| #if ENABLE_LFS |
| #define SENT_N_RECV_M "sent %llu, rcvd %llu\n" |
| unsigned long long wrote_out; /* total stdout bytes */ |
| unsigned long long wrote_net; /* total net bytes */ |
| #else |
| #define SENT_N_RECV_M "sent %u, rcvd %u\n" |
| unsigned wrote_out; /* total stdout bytes */ |
| unsigned wrote_net; /* total net bytes */ |
| #endif |
| char *proggie0saved; |
| /* ouraddr is never NULL and goes through three states as we progress: |
| 1 - local address before bind (IP/port possibly zero) |
| 2 - local address after bind (port is nonzero) |
| 3 - local address after connect??/recv/accept (IP and port are nonzero) */ |
| struct len_and_sockaddr *ouraddr; |
| /* themaddr is NULL if no peer hostname[:port] specified on command line */ |
| struct len_and_sockaddr *themaddr; |
| /* remend is set after connect/recv/accept to the actual ip:port of peer */ |
| struct len_and_sockaddr remend; |
| |
| jmp_buf jbuf; /* timer crud */ |
| |
| char bigbuf_in[BIGSIZ]; /* data buffers */ |
| char bigbuf_net[BIGSIZ]; |
| }; |
| |
| #define G (*ptr_to_globals) |
| #define wrote_out (G.wrote_out ) |
| #define wrote_net (G.wrote_net ) |
| #define ouraddr (G.ouraddr ) |
| #define themaddr (G.themaddr ) |
| #define remend (G.remend ) |
| #define jbuf (G.jbuf ) |
| #define bigbuf_in (G.bigbuf_in ) |
| #define bigbuf_net (G.bigbuf_net) |
| #define o_verbose (G.o_verbose ) |
| #define o_wait (G.o_wait ) |
| #if ENABLE_NC_EXTRA |
| #define o_interval (G.o_interval) |
| #else |
| #define o_interval 0 |
| #endif |
| #define INIT_G() do { \ |
| SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \ |
| } while (0) |
| |
| |
| /* Must match getopt32 call! */ |
| enum { |
| OPT_n = (1 << 0), |
| OPT_p = (1 << 1), |
| OPT_s = (1 << 2), |
| OPT_u = (1 << 3), |
| OPT_v = (1 << 4), |
| OPT_w = (1 << 5), |
| OPT_l = (1 << 6) * ENABLE_NC_SERVER, |
| OPT_k = (1 << 7) * ENABLE_NC_SERVER, |
| OPT_i = (1 << (6+2*ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA, |
| OPT_o = (1 << (7+2*ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA, |
| OPT_z = (1 << (8+2*ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA, |
| }; |
| |
| #define o_nflag (option_mask32 & OPT_n) |
| #define o_udpmode (option_mask32 & OPT_u) |
| #if ENABLE_NC_EXTRA |
| #define o_ofile (option_mask32 & OPT_o) |
| #define o_zero (option_mask32 & OPT_z) |
| #else |
| #define o_ofile 0 |
| #define o_zero 0 |
| #endif |
| |
| /* Debug: squirt whatever message and sleep a bit so we can see it go by. */ |
| /* Beware: writes to stdOUT... */ |
| #if 0 |
| #define Debug(...) do { printf(__VA_ARGS__); printf("\n"); fflush_all(); sleep(1); } while (0) |
| #else |
| #define Debug(...) do { } while (0) |
| #endif |
| |
| #define holler_error(...) do { if (o_verbose) bb_error_msg(__VA_ARGS__); } while (0) |
| #define holler_perror(...) do { if (o_verbose) bb_perror_msg(__VA_ARGS__); } while (0) |
| |
| /* catch: no-brainer interrupt handler */ |
| static void catch(int sig) |
| { |
| if (o_verbose > 1) /* normally we don't care */ |
| fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out); |
| fprintf(stderr, "punt!\n"); |
| kill_myself_with_sig(sig); |
| } |
| |
| /* unarm */ |
| static void unarm(void) |
| { |
| signal(SIGALRM, SIG_IGN); |
| alarm(0); |
| } |
| |
| /* timeout and other signal handling cruft */ |
| static void tmtravel(int sig UNUSED_PARAM) |
| { |
| unarm(); |
| longjmp(jbuf, 1); |
| } |
| |
| /* arm: set the timer. */ |
| static void arm(unsigned secs) |
| { |
| signal(SIGALRM, tmtravel); |
| alarm(secs); |
| } |
| |
| /* findline: |
| find the next newline in a buffer; return inclusive size of that "line", |
| or the entire buffer size, so the caller knows how much to then write(). |
| Not distinguishing \n vs \r\n for the nonce; it just works as is... */ |
| static unsigned findline(char *buf, unsigned siz) |
| { |
| char * p; |
| int x; |
| if (!buf) /* various sanity checks... */ |
| return 0; |
| if (siz > BIGSIZ) |
| return 0; |
| x = siz; |
| for (p = buf; x > 0; x--) { |
| if (*p == '\n') { |
| x = (int) (p - buf); |
| x++; /* 'sokay if it points just past the end! */ |
| Debug("findline returning %d", x); |
| return x; |
| } |
| p++; |
| } /* for */ |
| Debug("findline returning whole thing: %d", siz); |
| return siz; |
| } /* findline */ |
| |
| /* doexec: |
| fiddle all the file descriptors around, and hand off to another prog. Sort |
| of like a one-off "poor man's inetd". This is the only section of code |
| that would be security-critical, which is why it's ifdefed out by default. |
| Use at your own hairy risk; if you leave shells lying around behind open |
| listening ports you deserve to lose!! */ |
| static int doexec(char **proggie) NORETURN; |
| static int doexec(char **proggie) |
| { |
| if (G.proggie0saved) |
| proggie[0] = G.proggie0saved; |
| xmove_fd(netfd, 0); |
| dup2(0, 1); |
| /* dup2(0, 2); - do we *really* want this? NO! |
| * exec'ed prog can do it yourself, if needed */ |
| BB_EXECVP_or_die(proggie); |
| } |
| |
| /* connect_w_timeout: |
| return an fd for one of |
| an open outbound TCP connection, a UDP stub-socket thingie, or |
| an unconnected TCP or UDP socket to listen on. |
| Examines various global o_blah flags to figure out what to do. |
| lad can be NULL, then socket is not bound to any local ip[:port] */ |
| static int connect_w_timeout(int fd) |
| { |
| int rr; |
| |
| /* wrap connect inside a timer, and hit it */ |
| arm(o_wait); |
| if (setjmp(jbuf) == 0) { |
| rr = connect(fd, &themaddr->u.sa, themaddr->len); |
| unarm(); |
| } else { /* setjmp: connect failed... */ |
| rr = -1; |
| errno = ETIMEDOUT; /* fake it */ |
| } |
| return rr; |
| } |
| |
| /* dolisten: |
| listens for |
| incoming and returns an open connection *from* someplace. If we were |
| given host/port args, any connections from elsewhere are rejected. This |
| in conjunction with local-address binding should limit things nicely... */ |
| static void dolisten(int is_persistent, char **proggie) |
| { |
| int rr; |
| |
| if (!o_udpmode) |
| xlisten(netfd, 1); /* TCP: gotta listen() before we can get */ |
| |
| /* Various things that follow temporarily trash bigbuf_net, which might contain |
| a copy of any recvfrom()ed packet, but we'll read() another copy later. */ |
| |
| /* I can't believe I have to do all this to get my own goddamn bound address |
| and port number. It should just get filled in during bind() or something. |
| All this is only useful if we didn't say -p for listening, since if we |
| said -p we *know* what port we're listening on. At any rate we won't bother |
| with it all unless we wanted to see it, although listening quietly on a |
| random unknown port is probably not very useful without "netstat". */ |
| if (o_verbose) { |
| char *addr; |
| getsockname(netfd, &ouraddr->u.sa, &ouraddr->len); |
| //if (rr < 0) |
| // bb_perror_msg_and_die("getsockname after bind"); |
| addr = xmalloc_sockaddr2dotted(&ouraddr->u.sa); |
| fprintf(stderr, "listening on %s ...\n", addr); |
| free(addr); |
| } |
| |
| if (o_udpmode) { |
| /* UDP is a speeeeecial case -- we have to do I/O *and* get the calling |
| party's particulars all at once, listen() and accept() don't apply. |
| At least in the BSD universe, however, recvfrom/PEEK is enough to tell |
| us something came in, and we can set things up so straight read/write |
| actually does work after all. Yow. YMMV on strange platforms! */ |
| |
| /* I'm not completely clear on how this works -- BSD seems to make UDP |
| just magically work in a connect()ed context, but we'll undoubtedly run |
| into systems this deal doesn't work on. For now, we apparently have to |
| issue a connect() on our just-tickled socket so we can write() back. |
| Again, why the fuck doesn't it just get filled in and taken care of?! |
| This hack is anything but optimal. Basically, if you want your listener |
| to also be able to send data back, you need this connect() line, which |
| also has the side effect that now anything from a different source or even a |
| different port on the other end won't show up and will cause ICMP errors. |
| I guess that's what they meant by "connect". |
| Let's try to remember what the "U" is *really* for, eh? */ |
| |
| /* If peer address is specified, connect to it */ |
| remend.len = LSA_SIZEOF_SA; |
| if (themaddr) { |
| remend = *themaddr; |
| xconnect(netfd, &themaddr->u.sa, themaddr->len); |
| } |
| /* peek first packet and remember peer addr */ |
| arm(o_wait); /* might as well timeout this, too */ |
| if (setjmp(jbuf) == 0) { /* do timeout for initial connect */ |
| /* (*ouraddr) is prefilled with "default" address */ |
| /* and here we block... */ |
| rr = recv_from_to(netfd, NULL, 0, MSG_PEEK, /*was bigbuf_net, BIGSIZ*/ |
| &remend.u.sa, &ouraddr->u.sa, ouraddr->len); |
| if (rr < 0) |
| bb_perror_msg_and_die("recvfrom"); |
| unarm(); |
| } else |
| bb_error_msg_and_die("timeout"); |
| /* Now we learned *to which IP* peer has connected, and we want to anchor |
| our socket on it, so that our outbound packets will have correct local IP. |
| Unfortunately, bind() on already bound socket will fail now (EINVAL): |
| xbind(netfd, &ouraddr->u.sa, ouraddr->len); |
| Need to read the packet, save data, close this socket and |
| create new one, and bind() it. TODO */ |
| if (!themaddr) |
| xconnect(netfd, &remend.u.sa, ouraddr->len); |
| } else { |
| /* TCP */ |
| another: |
| arm(o_wait); /* wrap this in a timer, too; 0 = forever */ |
| if (setjmp(jbuf) == 0) { |
| again: |
| remend.len = LSA_SIZEOF_SA; |
| rr = accept(netfd, &remend.u.sa, &remend.len); |
| if (rr < 0) |
| bb_perror_msg_and_die("accept"); |
| if (themaddr) { |
| int sv_port, port, r; |
| |
| sv_port = get_nport(&remend.u.sa); /* save */ |
| port = get_nport(&themaddr->u.sa); |
| if (port == 0) { |
| /* "nc -nl -p LPORT RHOST" (w/o RPORT!): |
| * we should accept any remote port */ |
| set_nport(&remend.u.sa, 0); /* blot out remote port# */ |
| } |
| r = memcmp(&remend.u.sa, &themaddr->u.sa, remend.len); |
| set_nport(&remend.u.sa, sv_port); /* restore */ |
| if (r != 0) { |
| /* nc 1.10 bails out instead, and its error message |
| * is not suppressed by o_verbose */ |
| if (o_verbose) { |
| char *remaddr = xmalloc_sockaddr2dotted(&remend.u.sa); |
| bb_error_msg("connect from wrong ip/port %s ignored", remaddr); |
| free(remaddr); |
| } |
| close(rr); |
| goto again; |
| } |
| } |
| unarm(); |
| } else |
| bb_error_msg_and_die("timeout"); |
| |
| if (is_persistent && proggie) { |
| /* -l -k -e PROG */ |
| signal(SIGCHLD, SIG_IGN); /* no zombies please */ |
| if (xvfork() != 0) { |
| /* parent: go back and accept more connections */ |
| close(rr); |
| goto another; |
| } |
| /* child */ |
| signal(SIGCHLD, SIG_DFL); |
| } |
| |
| xmove_fd(rr, netfd); /* dump the old socket, here's our new one */ |
| /* find out what address the connection was *to* on our end, in case we're |
| doing a listen-on-any on a multihomed machine. This allows one to |
| offer different services via different alias addresses, such as the |
| "virtual web site" hack. */ |
| getsockname(netfd, &ouraddr->u.sa, &ouraddr->len); |
| //if (rr < 0) |
| // bb_perror_msg_and_die("getsockname after accept"); |
| } |
| |
| if (o_verbose) { |
| char *lcladdr, *remaddr, *remhostname; |
| |
| #if ENABLE_NC_EXTRA && defined(IP_OPTIONS) |
| /* If we can, look for any IP options. Useful for testing the receiving end of |
| such things, and is a good exercise in dealing with it. We do this before |
| the connect message, to ensure that the connect msg is uniformly the LAST |
| thing to emerge after all the intervening crud. Doesn't work for UDP on |
| any machines I've tested, but feel free to surprise me. */ |
| char optbuf[40]; |
| socklen_t x = sizeof(optbuf); |
| |
| rr = getsockopt(netfd, IPPROTO_IP, IP_OPTIONS, optbuf, &x); |
| if (rr >= 0 && x) { /* we've got options, lessee em... */ |
| *bin2hex(bigbuf_net, optbuf, x) = '\0'; |
| fprintf(stderr, "IP options: %s\n", bigbuf_net); |
| } |
| #endif |
| |
| /* now check out who it is. We don't care about mismatched DNS names here, |
| but any ADDR and PORT we specified had better fucking well match the caller. |
| Converting from addr to inet_ntoa and back again is a bit of a kludge, but |
| gethostpoop wants a string and there's much gnarlier code out there already, |
| so I don't feel bad. |
| The *real* question is why BFD sockets wasn't designed to allow listens for |
| connections *from* specific hosts/ports, instead of requiring the caller to |
| accept the connection and then reject undesireable ones by closing. |
| In other words, we need a TCP MSG_PEEK. */ |
| /* bbox: removed most of it */ |
| lcladdr = xmalloc_sockaddr2dotted(&ouraddr->u.sa); |
| remaddr = xmalloc_sockaddr2dotted(&remend.u.sa); |
| remhostname = o_nflag ? remaddr : xmalloc_sockaddr2host(&remend.u.sa); |
| fprintf(stderr, "connect to %s from %s (%s)\n", |
| lcladdr, remhostname, remaddr); |
| free(lcladdr); |
| free(remaddr); |
| if (!o_nflag) |
| free(remhostname); |
| } |
| |
| if (proggie) |
| doexec(proggie); |
| } |
| |
| /* udptest: |
| fire a couple of packets at a UDP target port, just to see if it's really |
| there. On BSD kernels, ICMP host/port-unreachable errors get delivered to |
| our socket as ECONNREFUSED write errors. On SV kernels, we lose; we'll have |
| to collect and analyze raw ICMP ourselves a la satan's probe_udp_ports |
| backend. Guess where one could swipe the appropriate code from... |
| |
| Use the time delay between writes if given, otherwise use the "tcp ping" |
| trick for getting the RTT. [I got that idea from pluvius, and warped it.] |
| Return either the original fd, or clean up and return -1. */ |
| #if ENABLE_NC_EXTRA |
| static int udptest(void) |
| { |
| int rr; |
| |
| rr = write(netfd, bigbuf_in, 1); |
| if (rr != 1) |
| bb_perror_msg("udptest first write"); |
| |
| if (o_wait) |
| sleep(o_wait); // can be interrupted! while (t) nanosleep(&t)? |
| else { |
| /* use the tcp-ping trick: try connecting to a normally refused port, which |
| causes us to block for the time that SYN gets there and RST gets back. |
| Not completely reliable, but it *does* mostly work. */ |
| /* Set a temporary connect timeout, so packet filtration doesnt cause |
| us to hang forever, and hit it */ |
| o_wait = 5; /* enough that we'll notice?? */ |
| rr = xsocket(ouraddr->u.sa.sa_family, SOCK_STREAM, 0); |
| set_nport(&themaddr->u.sa, htons(SLEAZE_PORT)); |
| connect_w_timeout(rr); |
| /* don't need to restore themaddr's port, it's not used anymore */ |
| close(rr); |
| o_wait = 0; /* restore */ |
| } |
| |
| rr = write(netfd, bigbuf_in, 1); |
| return (rr != 1); /* if rr == 1, return 0 (success) */ |
| } |
| #else |
| int udptest(void); |
| #endif |
| |
| /* oprint: |
| Hexdump bytes shoveled either way to a running logfile, in the format: |
| D offset - - - - --- 16 bytes --- - - - - # .... ascii ..... |
| where "which" sets the direction indicator, D: |
| 0 -- sent to network, or ">" |
| 1 -- rcvd and printed to stdout, or "<" |
| and "buf" and "n" are data-block and length. If the current block generates |
| a partial line, so be it; we *want* that lockstep indication of who sent |
| what when. Adapted from dgaudet's original example -- but must be ripping |
| *fast*, since we don't want to be too disk-bound... */ |
| #if ENABLE_NC_EXTRA |
| static void oprint(int direction, unsigned char *p, unsigned bc) |
| { |
| unsigned obc; /* current "global" offset */ |
| unsigned x; |
| unsigned char *op; /* out hexdump ptr */ |
| unsigned char *ap; /* out asc-dump ptr */ |
| unsigned char stage[100]; |
| |
| if (bc == 0) |
| return; |
| |
| obc = wrote_net; /* use the globals! */ |
| if (direction == '<') |
| obc = wrote_out; |
| stage[0] = direction; |
| stage[59] = '#'; /* preload separator */ |
| stage[60] = ' '; |
| |
| do { /* for chunk-o-data ... */ |
| x = 16; |
| if (bc < 16) { |
| /* memset(&stage[bc*3 + 11], ' ', 16*3 - bc*3); */ |
| memset(&stage[11], ' ', 16*3); |
| x = bc; |
| } |
| sprintf((char *)&stage[1], " %8.8x ", obc); /* xxx: still slow? */ |
| bc -= x; /* fix current count */ |
| obc += x; /* fix current offset */ |
| op = &stage[11]; /* where hex starts */ |
| ap = &stage[61]; /* where ascii starts */ |
| |
| do { /* for line of dump, however long ... */ |
| *op++ = 0x20 | bb_hexdigits_upcase[*p >> 4]; |
| *op++ = 0x20 | bb_hexdigits_upcase[*p & 0x0f]; |
| *op++ = ' '; |
| if ((*p > 31) && (*p < 127)) |
| *ap = *p; /* printing */ |
| else |
| *ap = '.'; /* nonprinting, loose def */ |
| ap++; |
| p++; |
| } while (--x); |
| *ap++ = '\n'; /* finish the line */ |
| xwrite(ofd, stage, ap - stage); |
| } while (bc); |
| } |
| #else |
| void oprint(int direction, unsigned char *p, unsigned bc); |
| #endif |
| |
| /* readwrite: |
| handle stdin/stdout/network I/O. Bwahaha!! -- the i/o loop from hell. |
| In this instance, return what might become our exit status. */ |
| static int readwrite(void) |
| { |
| char *zp = zp; /* gcc */ /* stdin buf ptr */ |
| char *np = np; /* net-in buf ptr */ |
| unsigned rzleft; |
| unsigned rnleft; |
| unsigned netretry; /* net-read retry counter */ |
| unsigned fds_open; |
| |
| struct pollfd pfds[2]; |
| pfds[0].fd = STDIN_FILENO; |
| pfds[0].events = POLLIN; |
| pfds[1].fd = netfd; |
| pfds[1].events = POLLIN; |
| |
| fds_open = 2; |
| netretry = 2; |
| rzleft = rnleft = 0; |
| if (o_interval) |
| sleep(o_interval); /* pause *before* sending stuff, too */ |
| |
| /* and now the big ol' shoveling loop ... */ |
| /* nc 1.10 has "while (FD_ISSET(netfd)" here */ |
| while (fds_open) { |
| int rr; |
| int poll_tmout_ms; |
| unsigned wretry = 8200; /* net-write sanity counter */ |
| |
| poll_tmout_ms = -1; |
| if (o_wait) { |
| poll_tmout_ms = INT_MAX; |
| if (o_wait < INT_MAX / 1000) |
| poll_tmout_ms = o_wait * 1000; |
| } |
| rr = poll(pfds, 2, poll_tmout_ms); |
| if (rr < 0 && errno != EINTR) { /* might have gotten ^Zed, etc */ |
| holler_perror("poll"); |
| close(netfd); |
| return 1; |
| } |
| /* if we have a timeout AND stdin is closed AND we haven't heard anything |
| from the net during that time, assume it's dead and close it too. */ |
| if (rr == 0) { |
| if (!pfds[0].revents) { |
| netretry--; /* we actually try a coupla times. */ |
| if (!netretry) { |
| if (o_verbose > 1) /* normally we don't care */ |
| fprintf(stderr, "net timeout\n"); |
| /*close(netfd); - redundant, exit will do it */ |
| return 0; /* not an error! */ |
| } |
| } |
| } /* timeout */ |
| |
| /* Ding!! Something arrived, go check all the incoming hoppers, net first */ |
| if (pfds[1].revents) { /* net: ding! */ |
| rr = read(netfd, bigbuf_net, BIGSIZ); |
| if (rr <= 0) { |
| if (rr < 0 && o_verbose > 1) { |
| /* nc 1.10 doesn't do this */ |
| bb_perror_msg("net read"); |
| } |
| pfds[1].fd = -1; /* don't poll for netfd anymore */ |
| fds_open--; |
| rzleft = 0; /* can't write anymore: broken pipe */ |
| } else { |
| rnleft = rr; |
| np = bigbuf_net; |
| } |
| Debug("got %d from the net, errno %d", rr, errno); |
| } /* net:ding */ |
| |
| /* if we're in "slowly" mode there's probably still stuff in the stdin |
| buffer, so don't read unless we really need MORE INPUT! MORE INPUT! */ |
| if (rzleft) |
| goto shovel; |
| |
| /* okay, suck more stdin */ |
| if (pfds[0].revents) { /* stdin: ding! */ |
| rr = read(STDIN_FILENO, bigbuf_in, BIGSIZ); |
| /* Considered making reads here smaller for UDP mode, but 8192-byte |
| mobygrams are kinda fun and exercise the reassembler. */ |
| if (rr <= 0) { /* at end, or fukt, or ... */ |
| pfds[0].fd = -1; /* disable stdin */ |
| /*close(STDIN_FILENO); - not really necessary */ |
| /* Let peer know we have no more data */ |
| /* nc 1.10 doesn't do this: */ |
| shutdown(netfd, SHUT_WR); |
| fds_open--; |
| } else { |
| rzleft = rr; |
| zp = bigbuf_in; |
| } |
| } /* stdin:ding */ |
| shovel: |
| /* now that we've dingdonged all our thingdings, send off the results. |
| Geez, why does this look an awful lot like the big loop in "rsh"? ... |
| not sure if the order of this matters, but write net -> stdout first. */ |
| |
| if (rnleft) { |
| rr = write(STDOUT_FILENO, np, rnleft); |
| if (rr > 0) { |
| if (o_ofile) /* log the stdout */ |
| oprint('<', (unsigned char *)np, rr); |
| np += rr; |
| rnleft -= rr; |
| wrote_out += rr; /* global count */ |
| } |
| Debug("wrote %d to stdout, errno %d", rr, errno); |
| } /* rnleft */ |
| if (rzleft) { |
| if (o_interval) /* in "slowly" mode ?? */ |
| rr = findline(zp, rzleft); |
| else |
| rr = rzleft; |
| rr = write(netfd, zp, rr); /* one line, or the whole buffer */ |
| if (rr > 0) { |
| if (o_ofile) /* log what got sent */ |
| oprint('>', (unsigned char *)zp, rr); |
| zp += rr; |
| rzleft -= rr; |
| wrote_net += rr; /* global count */ |
| } |
| Debug("wrote %d to net, errno %d", rr, errno); |
| } /* rzleft */ |
| if (o_interval) { /* cycle between slow lines, or ... */ |
| sleep(o_interval); |
| continue; /* ...with hairy loop... */ |
| } |
| if (rzleft || rnleft) { /* shovel that shit till they ain't */ |
| wretry--; /* none left, and get another load */ |
| /* net write retries sometimes happen on UDP connections */ |
| if (!wretry) { /* is something hung? */ |
| holler_error("too many output retries"); |
| return 1; |
| } |
| goto shovel; |
| } |
| } /* while (fds_open) */ |
| |
| /* XXX: maybe want a more graceful shutdown() here, or screw around with |
| linger times?? I suspect that I don't need to since I'm always doing |
| blocking reads and writes and my own manual "last ditch" efforts to read |
| the net again after a timeout. I haven't seen any screwups yet, but it's |
| not like my test network is particularly busy... */ |
| close(netfd); |
| return 0; |
| } /* readwrite */ |
| |
| /* main: now we pull it all together... */ |
| int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| int nc_main(int argc UNUSED_PARAM, char **argv) |
| { |
| char *str_p, *str_s; |
| IF_NC_EXTRA(char *str_i, *str_o;) |
| char *themdotted = themdotted; /* for compiler */ |
| char **proggie; |
| int x; |
| unsigned cnt_l = 0; |
| unsigned o_lport = 0; |
| |
| INIT_G(); |
| |
| /* catch a signal or two for cleanup */ |
| bb_signals(0 |
| + (1 << SIGINT) |
| + (1 << SIGQUIT) |
| + (1 << SIGTERM) |
| , catch); |
| /* and suppress others... */ |
| bb_signals(0 |
| #ifdef SIGURG |
| + (1 << SIGURG) |
| #endif |
| + (1 << SIGPIPE) /* important! */ |
| , SIG_IGN); |
| |
| proggie = argv; |
| while (*++proggie) { |
| if (strcmp(*proggie, "-e") == 0) { |
| *proggie = NULL; |
| proggie++; |
| goto e_found; |
| } |
| /* -<other_opts>e PROG [ARGS] ? */ |
| /* (aboriginal linux uses this form) */ |
| if (proggie[0][0] == '-') { |
| char *optpos = *proggie + 1; |
| /* Skip all valid opts w/o params */ |
| optpos = optpos + strspn(optpos, "nuv"IF_NC_SERVER("lk")IF_NC_EXTRA("z")); |
| if (*optpos == 'e' && !optpos[1]) { |
| *optpos = '\0'; |
| proggie++; |
| G.proggie0saved = *proggie; |
| *proggie = NULL; /* terminate argv for getopt32 */ |
| goto e_found; |
| } |
| } |
| } |
| proggie = NULL; |
| e_found: |
| |
| // -g -G -t -r deleted, unimplemented -a deleted too |
| opt_complementary = "?2:vv:ll"; /* max 2 params; -v and -l are counters; -w N */ |
| getopt32(argv, "np:s:uvw:+" IF_NC_SERVER("lk") |
| IF_NC_EXTRA("i:o:z"), |
| &str_p, &str_s, &o_wait |
| IF_NC_EXTRA(, &str_i, &str_o), &o_verbose IF_NC_SERVER(, &cnt_l)); |
| argv += optind; |
| #if ENABLE_NC_EXTRA |
| if (option_mask32 & OPT_i) /* line-interval time */ |
| o_interval = xatou_range(str_i, 1, 0xffff); |
| #endif |
| #if ENABLE_NC_SERVER |
| //if (option_mask32 & OPT_l) /* listen mode */ |
| if (option_mask32 & OPT_k) /* persistent server mode */ |
| cnt_l = 2; |
| #endif |
| //if (option_mask32 & OPT_n) /* numeric-only, no DNS lookups */ |
| //if (option_mask32 & OPT_o) /* hexdump log */ |
| if (option_mask32 & OPT_p) { /* local source port */ |
| o_lport = bb_lookup_port(str_p, o_udpmode ? "udp" : "tcp", 0); |
| if (!o_lport) |
| bb_error_msg_and_die("bad local port '%s'", str_p); |
| } |
| //if (option_mask32 & OPT_r) /* randomize various things */ |
| //if (option_mask32 & OPT_u) /* use UDP */ |
| //if (option_mask32 & OPT_v) /* verbose */ |
| //if (option_mask32 & OPT_w) /* wait time */ |
| //if (option_mask32 & OPT_z) /* little or no data xfer */ |
| |
| /* We manage our fd's so that they are never 0,1,2 */ |
| /*bb_sanitize_stdio(); - not needed */ |
| |
| if (argv[0]) { |
| themaddr = xhost2sockaddr(argv[0], |
| argv[1] |
| ? bb_lookup_port(argv[1], o_udpmode ? "udp" : "tcp", 0) |
| : 0); |
| } |
| |
| /* create & bind network socket */ |
| x = (o_udpmode ? SOCK_DGRAM : SOCK_STREAM); |
| if (option_mask32 & OPT_s) { /* local address */ |
| /* if o_lport is still 0, then we will use random port */ |
| ouraddr = xhost2sockaddr(str_s, o_lport); |
| #ifdef BLOAT |
| /* prevent spurious "UDP listen needs !0 port" */ |
| o_lport = get_nport(ouraddr); |
| o_lport = ntohs(o_lport); |
| #endif |
| x = xsocket(ouraddr->u.sa.sa_family, x, 0); |
| } else { |
| /* We try IPv6, then IPv4, unless addr family is |
| * implicitly set by way of remote addr/port spec */ |
| x = xsocket_type(&ouraddr, |
| (themaddr ? themaddr->u.sa.sa_family : AF_UNSPEC), |
| x); |
| if (o_lport) |
| set_nport(&ouraddr->u.sa, htons(o_lport)); |
| } |
| xmove_fd(x, netfd); |
| setsockopt_reuseaddr(netfd); |
| if (o_udpmode) |
| socket_want_pktinfo(netfd); |
| if (!ENABLE_FEATURE_UNIX_LOCAL |
| || cnt_l != 0 /* listen */ |
| || ouraddr->u.sa.sa_family != AF_UNIX |
| ) { |
| xbind(netfd, &ouraddr->u.sa, ouraddr->len); |
| } |
| #if 0 |
| setsockopt_SOL_SOCKET_int(netfd, SO_RCVBUF, o_rcvbuf); |
| setsockopt_SOL_SOCKET_int(netfd, SO_SNDBUF, o_sndbuf); |
| #endif |
| |
| #ifdef BLOAT |
| if (OPT_l && (option_mask32 & (OPT_u|OPT_l)) == (OPT_u|OPT_l)) { |
| /* apparently UDP can listen ON "port 0", |
| but that's not useful */ |
| if (!o_lport) |
| bb_error_msg_and_die("UDP listen needs nonzero -p port"); |
| } |
| #endif |
| |
| if (proggie) { |
| close(STDIN_FILENO); /* won't need stdin */ |
| option_mask32 &= ~OPT_o; /* -o with -e is meaningless! */ |
| } |
| #if ENABLE_NC_EXTRA |
| if (o_ofile) |
| xmove_fd(xopen(str_o, O_WRONLY|O_CREAT|O_TRUNC), ofd); |
| #endif |
| |
| if (cnt_l != 0) { |
| dolisten((cnt_l - 1), proggie); |
| /* dolisten does its own connect reporting */ |
| x = readwrite(); /* it even works with UDP! */ |
| } else { |
| /* Outbound connects. Now we're more picky about args... */ |
| if (!themaddr) |
| bb_show_usage(); |
| |
| remend = *themaddr; |
| if (o_verbose) |
| themdotted = xmalloc_sockaddr2dotted(&themaddr->u.sa); |
| |
| x = connect_w_timeout(netfd); |
| if (o_zero && x == 0 && o_udpmode) /* if UDP scanning... */ |
| x = udptest(); |
| if (x == 0) { /* Yow, are we OPEN YET?! */ |
| if (o_verbose) |
| fprintf(stderr, "%s (%s) open\n", argv[0], themdotted); |
| if (proggie) /* exec is valid for outbound, too */ |
| doexec(proggie); |
| if (!o_zero) |
| x = readwrite(); |
| } else { /* connect or udptest wasn't successful */ |
| x = 1; /* exit status */ |
| /* if we're scanning at a "one -v" verbosity level, don't print refusals. |
| Give it another -v if you want to see everything. */ |
| if (o_verbose > 1 || (o_verbose && errno != ECONNREFUSED)) |
| bb_perror_msg("%s (%s)", argv[0], themdotted); |
| } |
| } |
| if (o_verbose > 1) /* normally we don't care */ |
| fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out); |
| return x; |
| } |