diff options
Diffstat (limited to 'netcat.c')
| -rw-r--r-- | netcat.c | 1668 |
1 files changed, 1668 insertions, 0 deletions
diff --git a/netcat.c b/netcat.c new file mode 100644 index 0000000..5ceb4f1 --- /dev/null +++ b/netcat.c @@ -0,0 +1,1668 @@ +/* Netcat 1.10 RELEASE 960320 + + 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. + + Read the README for the whole story, doc, applications, etc. + + Layout: + conditional includes: + includes: + handy defines: + globals: + malloced globals: + cmd-flag globals: + support routines: + readwrite select loop: + main: + + bluesky: + parse ranges of IP address as well as ports, perhaps + RAW mode! + backend progs to grab a pty and look like a real telnetd?! + backend progs to do various encryption modes??!?! +*/ + +#include "generic.h" /* same as with L5, skey, etc */ + +/* conditional includes -- a very messy section which you may have to dink + for your own architecture [and please send diffs...]: */ +/* #undef _POSIX_SOURCE /* might need this for something? */ +#define HAVE_BIND /* ASSUMPTION -- seems to work everywhere! */ +#define HAVE_HELP /* undefine if you dont want the help text */ +/* #define ANAL /* if you want case-sensitive DNS matching */ + +#ifdef HAVE_STDLIB_H +#include <stdlib.h> +#else +#include <malloc.h> +#endif +#ifdef HAVE_SELECT_H /* random SV variants need this */ +#include <sys/select.h> +#endif + +/* have to do this *before* including types.h. xxx: Linux still has it wrong */ +#ifdef FD_SETSIZE /* should be in types.h, butcha never know. */ +#undef FD_SETSIZE /* if we ever need more than 16 active */ +#endif /* fd's, something is horribly wrong! */ +#define FD_SETSIZE 16 /* <-- this'll give us a long anyways, wtf */ +#include <sys/types.h> /* *now* do it. Sigh, this is broken */ + +#ifdef HAVE_RANDOM /* aficionados of ?rand48() should realize */ +#define SRAND srandom /* that this doesn't need *strong* random */ +#define RAND random /* numbers just to mix up port numbers!! */ +#else +#define SRAND srand +#define RAND rand +#endif /* HAVE_RANDOM */ + +/* includes: */ +#include <sys/time.h> /* timeval, time_t */ +#include <setjmp.h> /* jmp_buf et al */ +#include <sys/socket.h> /* basics, SO_ and AF_ defs, sockaddr, ... */ +#include <netinet/in.h> /* sockaddr_in, htons, in_addr */ +#include <netinet/in_systm.h> /* misc crud that netinet/ip.h references */ +#include <netinet/ip.h> /* IPOPT_LSRR, header stuff */ +#include <netdb.h> /* hostent, gethostby*, getservby* */ +#include <arpa/inet.h> /* inet_ntoa */ +#include <stdio.h> +#include <string.h> /* strcpy, strchr, yadda yadda */ +#include <errno.h> +#include <signal.h> +#include <fcntl.h> /* O_WRONLY et al */ + +/* handy stuff: */ +#define SA struct sockaddr /* socket overgeneralization braindeath */ +#define SAI struct sockaddr_in /* ... whoever came up with this model */ +#define IA struct in_addr /* ... should be taken out and shot, */ + /* ... not that TLI is any better. sigh.. */ +#define SLEAZE_PORT 31337 /* for UDP-scan RTT trick, change if ya want */ +#define USHORT unsigned short /* use these for options an' stuff */ +#define BIGSIZ 8192 /* big buffers */ + +#ifndef INADDR_NONE +#define INADDR_NONE 0xffffffff +#endif +#ifdef MAXHOSTNAMELEN +#undef MAXHOSTNAMELEN /* might be too small on aix, so fix it */ +#endif +#define MAXHOSTNAMELEN 256 + +struct host_poop { + char name[MAXHOSTNAMELEN]; /* dns name */ + char addrs[8][24]; /* ascii-format IP addresses */ + struct in_addr iaddrs[8]; /* real addresses: in_addr.s_addr: ulong */ +}; +#define HINF struct host_poop + +struct port_poop { + char name [64]; /* name in /etc/services */ + char anum [8]; /* ascii-format number */ + USHORT num; /* real host-order number */ +}; +#define PINF struct port_poop + +/* globals: */ +jmp_buf jbuf; /* timer crud */ +int jval = 0; /* timer crud */ +int netfd = -1; +int ofd = 0; /* hexdump output fd */ +static char unknown[] = "(UNKNOWN)"; +static char p_tcp[] = "tcp"; /* for getservby* */ +static char p_udp[] = "udp"; +#ifdef HAVE_BIND +extern int h_errno; +/* stolen almost wholesale from bsd herror.c */ +static char * h_errs[] = { + "Error 0", /* but we *don't* use this */ + "Unknown host", /* 1 HOST_NOT_FOUND */ + "Host name lookup failure", /* 2 TRY_AGAIN */ + "Unknown server error", /* 3 NO_RECOVERY */ + "No address associated with name", /* 4 NO_ADDRESS */ +}; +#else +int h_errno; /* just so we *do* have it available */ +#endif /* HAVE_BIND */ +int gatesidx = 0; /* LSRR hop count */ +int gatesptr = 4; /* initial LSRR pointer, settable */ +USHORT Single = 1; /* zero if scanning */ +unsigned int insaved = 0; /* stdin-buffer size for multi-mode */ +unsigned int wrote_out = 0; /* total stdout bytes */ +unsigned int wrote_net = 0; /* total net bytes */ +static char wrote_txt[] = " sent %d, rcvd %d"; +static char hexnibs[20] = "0123456789abcdef "; + +/* will malloc up the following globals: */ +struct timeval * timer1 = NULL; +struct timeval * timer2 = NULL; +SAI * lclend = NULL; /* sockaddr_in structs */ +SAI * remend = NULL; +HINF ** gates = NULL; /* LSRR hop hostpoop */ +char * optbuf = NULL; /* LSRR or sockopts */ +char * bigbuf_in; /* data buffers */ +char * bigbuf_net; +fd_set * ding1; /* for select loop */ +fd_set * ding2; +PINF * portpoop = NULL; /* for getportpoop / getservby* */ +unsigned char * stage = NULL; /* hexdump line buffer */ + +/* global cmd flags: */ +USHORT o_alla = 0; +unsigned int o_interval = 0; +USHORT o_listen = 0; +USHORT o_nflag = 0; +USHORT o_wfile = 0; +USHORT o_random = 0; +USHORT o_udpmode = 0; +USHORT o_verbose = 0; +unsigned int o_wait = 0; +USHORT o_zero = 0; +/* o_tn in optional section */ + +/* Debug macro: squirt whatever message and sleep a bit so we can see it go + by. need to call like Debug ((stuff)) [with no ; ] so macro args match! + Beware: writes to stdOUT... */ +#ifdef DEBUG +#define Debug(x) printf x; printf ("\n"); fflush (stdout); sleep (1); +#else +#define Debug(x) /* nil... */ +#endif + + +/* support routines -- the bulk of this thing. Placed in such an order that + we don't have to forward-declare anything: */ + +/* holler : + fake varargs -- need to do this way because we wind up calling through + more levels of indirection than vanilla varargs can handle, and not all + machines have vfprintf/vsyslog/whatever! 6 params oughta be enough. */ +void holler (str, p1, p2, p3, p4, p5, p6) + char * str; + char * p1, * p2, * p3, * p4, * p5, * p6; +{ + if (o_verbose) { + fprintf (stderr, str, p1, p2, p3, p4, p5, p6); +#ifdef HAVE_BIND + if (h_errno) { /* if host-lookup variety of error ... */ + if (h_errno > 4) /* oh no you don't, either */ + fprintf (stderr, "preposterous h_errno: %d", h_errno); + else + fprintf (stderr, h_errs[h_errno]); /* handle it here */ + h_errno = 0; /* and reset for next call */ + } +#endif + if (errno) { /* this gives funny-looking messages, but */ + perror (" "); /* it's more portable than sys_errlist[]... */ + } else /* xxx: do something better? */ + fprintf (stderr, "\n"); + fflush (stderr); + } +} /* holler */ + +/* bail : + error-exit handler, callable from anywhere */ +void bail (str, p1, p2, p3, p4, p5, p6) + char * str; + char * p1, * p2, * p3, * p4, * p5, * p6; +{ + o_verbose = 1; + holler (str, p1, p2, p3, p4, p5, p6); + close (netfd); + sleep (1); + exit (1); +} /* bail */ + +/* catch : + no-brainer interrupt handler */ +void catch () +{ + errno = 0; + if (o_verbose > 1) /* normally we don't care */ + bail (wrote_txt, wrote_net, wrote_out); + bail (" punt!"); +} + +/* timeout and other signal handling cruft */ +void tmtravel () +{ + signal (SIGALRM, SIG_IGN); + alarm (0); + if (jval == 0) + bail ("spurious timer interrupt!"); + longjmp (jbuf, jval); +} + +/* arm : + set the timer. Zero secs arg means unarm */ +void arm (num, secs) + unsigned int num; + unsigned int secs; +{ + if (secs == 0) { /* reset */ + signal (SIGALRM, SIG_IGN); + alarm (0); + jval = 0; + } else { /* set */ + signal (SIGALRM, tmtravel); + alarm (secs); + jval = num; + } /* if secs */ +} /* arm */ + +/* Hmalloc : + malloc up what I want, rounded up to *4, and pre-zeroed. Either succeeds + or bails out on its own, so that callers don't have to worry about it. */ +char * Hmalloc (size) + unsigned int size; +{ + unsigned int s = (size + 4) & 0xfffffffc; /* 4GB?! */ + char * p = malloc (s); + if (p != NULL) + memset (p, 0, s); + else + bail ("Hmalloc %d failed", s); + return (p); +} /* Hmalloc */ + +/* 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... */ +unsigned int findline (buf, siz) + char * buf; + unsigned int siz; +{ + register char * p; + register 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 */ + +/* comparehosts : + cross-check the host_poop we have so far against new gethostby*() info, + and holler about mismatches. Perhaps gratuitous, but it can't hurt to + point out when someone's DNS is fukt. Returns 1 if mismatch, in case + someone else wants to do something about it. */ +int comparehosts (poop, hp) + HINF * poop; + struct hostent * hp; +{ + errno = 0; + h_errno = 0; +/* The DNS spec is officially case-insensitive, but for those times when you + *really* wanna see any and all discrepancies, by all means define this. */ +#ifdef ANAL + if (strcmp (poop->name, hp->h_name) != 0) { /* case-sensitive */ +#else + if (strcasecmp (poop->name, hp->h_name) != 0) { /* normal */ +#endif + holler ("DNS fwd/rev mismatch: %s != %s", poop->name, hp->h_name); + return (1); + } + return (0); +/* ... do we need to do anything over and above that?? */ +} /* comparehosts */ + +/* gethostpoop : + resolve a host 8 ways from sunday; return a new host_poop struct with its + info. The argument can be a name or [ascii] IP address; it will try its + damndest to deal with it. "numeric" governs whether we do any DNS at all, + and we also check o_verbose for what's appropriate work to do. */ +HINF * gethostpoop (name, numeric) + char * name; + USHORT numeric; +{ + struct hostent * hostent; + struct in_addr iaddr; + register HINF * poop = NULL; + register int x; + +/* I really want to strangle the twit who dreamed up all these sockaddr and + hostent abstractions, and then forced them all to be incompatible with + each other so you *HAVE* to do all this ridiculous casting back and forth. + If that wasn't bad enough, all the doc insists on referring to local ports + and addresses as "names", which makes NO sense down at the bare metal. + + What an absolutely horrid paradigm, and to think of all the people who + have been wasting significant amounts of time fighting with this stupid + deliberate obfuscation over the last 10 years... then again, I like + languages wherein a pointer is a pointer, what you put there is your own + business, the compiler stays out of your face, and sheep are nervous. + Maybe that's why my C code reads like assembler half the time... */ + +/* If we want to see all the DNS stuff, do the following hair -- + if inet_addr, do reverse and forward with any warnings; otherwise try + to do forward and reverse with any warnings. In other words, as long + as we're here, do a complete DNS check on these clowns. Yes, it slows + things down a bit for a first run, but once it's cached, who cares? */ + + errno = 0; + h_errno = 0; + if (name) + poop = (HINF *) Hmalloc (sizeof (HINF)); + if (! poop) + bail ("gethostpoop fuxored"); + strcpy (poop->name, unknown); /* preload it */ +/* see wzv:workarounds.c for dg/ux return-a-struct inet_addr lossage */ + iaddr.s_addr = inet_addr (name); + + if (iaddr.s_addr == INADDR_NONE) { /* here's the great split: names... */ + if (numeric) + bail ("Can't parse %s as an IP address", name); + hostent = gethostbyname (name); + if (! hostent) +/* failure to look up a name is fatal, since we can't do anything with it */ + bail ("%s: forward host lookup failed: ", name); + strncpy (poop->name, hostent->h_name, MAXHOSTNAMELEN - 2); + for (x = 0; hostent->h_addr_list[x] && (x < 8); x++) { + memcpy (&poop->iaddrs[x], hostent->h_addr_list[x], sizeof (IA)); + strncpy (poop->addrs[x], inet_ntoa (poop->iaddrs[x]), + sizeof (poop->addrs[0])); + } /* for x -> addrs, part A */ + if (! o_verbose) /* if we didn't want to see the */ + return (poop); /* inverse stuff, we're done. */ +/* do inverse lookups in separate loop based on our collected forward addrs, + since gethostby* tends to crap into the same buffer over and over */ + for (x = 0; poop->iaddrs[x].s_addr && (x < 8); x++) { + hostent = gethostbyaddr ((char *)&poop->iaddrs[x], + sizeof (IA), AF_INET); + if ((! hostent) || (! hostent-> h_name)) + holler ("Warning: inverse host lookup failed for %s: ", + poop->addrs[x]); + else + (void) comparehosts (poop, hostent); + } /* for x -> addrs, part B */ + + } else { /* not INADDR_NONE: numeric addresses... */ + memcpy (poop->iaddrs, &iaddr, sizeof (IA)); + strncpy (poop->addrs[0], inet_ntoa (iaddr), sizeof (poop->addrs)); + if (numeric) /* if numeric-only, we're done */ + return (poop); + if (! o_verbose) /* likewise if we don't want */ + return (poop); /* the full DNS hair */ + hostent = gethostbyaddr ((char *) &iaddr, sizeof (IA), AF_INET); +/* numeric or not, failure to look up a PTR is *not* considered fatal */ + if (! hostent) + holler ("%s: inverse host lookup failed: ", name); + else { + strncpy (poop->name, hostent->h_name, MAXHOSTNAMELEN - 2); + hostent = gethostbyname (poop->name); + if ((! hostent) || (! hostent->h_addr_list[0])) + holler ("Warning: forward host lookup failed for %s: ", + poop->name); + else + (void) comparehosts (poop, hostent); + } /* if hostent */ + } /* INADDR_NONE Great Split */ + +/* whatever-all went down previously, we should now have a host_poop struct + with at least one IP address in it. */ + h_errno = 0; + return (poop); +} /* gethostpoop */ + +/* getportpoop : + Same general idea as gethostpoop -- look up a port in /etc/services, fill + in global port_poop, but return the actual port *number*. Pass ONE of: + pstring to resolve stuff like "23" or "exec"; + pnum to reverse-resolve something that's already a number. + If o_nflag is on, fill in what we can but skip the getservby??? stuff. + Might as well have consistent behavior here, and it *is* faster. */ +USHORT getportpoop (pstring, pnum) + char * pstring; + unsigned int pnum; +{ + struct servent * servent; + register int x; + register int y; + char * whichp = p_tcp; + if (o_udpmode) + whichp = p_udp; + portpoop->name[0] = '?'; /* fast preload */ + portpoop->name[1] = '\0'; + +/* case 1: reverse-lookup of a number; placed first since this case is much + more frequent if we're scanning */ + if (pnum) { + if (pstring) /* one or the other, pleeze */ + return (0); + x = pnum; + if (o_nflag) /* go faster, skip getservbyblah */ + goto gp_finish; + y = htons (x); /* gotta do this -- see Fig.1 below */ + servent = getservbyport (y, whichp); + if (servent) { + y = ntohs (servent->s_port); + if (x != y) /* "never happen" */ + holler ("Warning: port-bynum mismatch, %d != %d", x, y); + strncpy (portpoop->name, servent->s_name, sizeof (portpoop->name)); + } /* if servent */ + goto gp_finish; + } /* if pnum */ + +/* case 2: resolve a string, but we still give preference to numbers instead + of trying to resolve conflicts. None of the entries in *my* extensive + /etc/services begins with a digit, so this should "always work" unless + you're at 3com and have some company-internal services defined... */ + if (pstring) { + if (pnum) /* one or the other, pleeze */ + return (0); + x = atoi (pstring); + if (x) + return (getportpoop (NULL, x)); /* recurse for numeric-string-arg */ + if (o_nflag) /* can't use names! */ + return (0); + servent = getservbyname (pstring, whichp); + if (servent) { + strncpy (portpoop->name, servent->s_name, sizeof (portpoop->name)); + x = ntohs (servent->s_port); + goto gp_finish; + } /* if servent */ + } /* if pstring */ + + return (0); /* catches any problems so far */ + +/* Obligatory netdb.h-inspired rant: servent.s_port is supposed to be an int. + Despite this, we still have to treat it as a short when copying it around. + Not only that, but we have to convert it *back* into net order for + getservbyport to work. Manpages generally aren't clear on all this, but + there are plenty of examples in which it is just quietly done. More BSD + lossage... since everything getserv* ever deals with is local to our own + host, why bother with all this network-order/host-order crap at all?! + That should be saved for when we want to actually plug the port[s] into + some real network calls -- and guess what, we have to *re*-convert at that + point as well. Fuckheads. */ + +gp_finish: +/* Fall here whether or not we have a valid servent at this point, with + x containing our [host-order and therefore useful, dammit] port number */ + sprintf (portpoop->anum, "%d", x); /* always load any numeric specs! */ + portpoop->num = (x & 0xffff); /* ushort, remember... */ + return (portpoop->num); +} /* getportpoop */ + +/* nextport : + Come up with the next port to try, be it random or whatever. "block" is + a ptr to randports array, whose bytes [so far] carry these meanings: + 0 ignore + 1 to be tested + 2 tested [which is set as we find them here] + returns a USHORT random port, or 0 if all the t-b-t ones are used up. */ +USHORT nextport (block) + char * block; +{ + register unsigned int x; + register unsigned int y; + + y = 70000; /* high safety count for rnd-tries */ + while (y > 0) { + x = (RAND() & 0xffff); + if (block[x] == 1) { /* try to find a not-done one... */ + block[x] = 2; + break; + } + x = 0; /* bummer. */ + y--; + } /* while y */ + if (x) + return (x); + + y = 65535; /* no random one, try linear downsearch */ + while (y > 0) { /* if they're all used, we *must* be sure! */ + if (block[y] == 1) { + block[y] = 2; + break; + } + y--; + } /* while y */ + if (y) + return (y); /* at least one left */ + + return (0); /* no more left! */ +} /* nextport */ + +/* loadports : + set "to be tested" indications in BLOCK, from LO to HI. Almost too small + to be a separate routine, but makes main() a little cleaner... */ +void loadports (block, lo, hi) + char * block; + USHORT lo; + USHORT hi; +{ + USHORT x; + + if (! block) + bail ("loadports: no block?!"); + if ((! lo) || (! hi)) + bail ("loadports: bogus values %d, %d", lo, hi); + x = hi; + while (lo <= x) { + block[x] = 1; + x--; + } +} /* loadports */ + +#ifdef GAPING_SECURITY_HOLE +char * pr00gie = NULL; /* global ptr to -e arg */ + +/* 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!! */ +doexec (fd) + int fd; +{ + register char * p; + + dup2 (fd, 0); /* the precise order of fiddlage */ + close (fd); /* is apparently crucial; this is */ + dup2 (0, 1); /* swiped directly out of "inetd". */ + dup2 (0, 2); + p = strrchr (pr00gie, '/'); /* shorter argv[0] */ + if (p) + p++; + else + p = pr00gie; +Debug (("gonna exec %s as %s...", pr00gie, p)) + execl (pr00gie, p, NULL); + bail ("exec %s failed", pr00gie); /* this gets sent out. Hmm... */ +} /* doexec */ +#endif /* GAPING_SECURITY_HOLE */ + +/* doconnect : + do all the socket stuff, and return an fd for one of + an open outbound TCP connection + a UDP stub-socket thingie + with appropriate socket options set up if we wanted source-routing, or + an unconnected TCP or UDP socket to listen on. + Examines various global o_blah flags to figure out what-all to do. */ +int doconnect (rad, rp, lad, lp) + IA * rad; + USHORT rp; + IA * lad; + USHORT lp; +{ + register int nnetfd; + register int rr; + int x, y; + errno = 0; + +/* grab a socket; set opts */ +newskt: + if (o_udpmode) + nnetfd = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP); + else + nnetfd = socket (AF_INET, SOCK_STREAM, IPPROTO_TCP); + if (nnetfd < 0) + bail ("Can't get socket"); + if (nnetfd == 0) /* if stdin was closed this might *be* 0, */ + goto newskt; /* so grab another. See text for why... */ + x = 1; + rr = setsockopt (nnetfd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof (x)); + if (rr == -1) + holler ("nnetfd reuseaddr failed"); /* ??? */ +#ifdef SO_REUSEPORT /* doesnt exist everywhere... */ + rr = setsockopt (nnetfd, SOL_SOCKET, SO_REUSEPORT, &x, sizeof (x)); + if (rr == -1) + holler ("nnetfd reuseport failed"); /* ??? */ +#endif +#if 0 +/* If you want to screw with RCVBUF/SNDBUF, do it here. Liudvikas Bukys at + Rochester sent this example, which would involve YET MORE options and is + just archived here in case you want to mess with it. o_xxxbuf are global + integers set in main() getopt loop, and check for rr == 0 afterward. */ + rr = setsockopt(nnetfd, SOL_SOCKET, SO_RCVBUF, &o_rcvbuf, sizeof o_rcvbuf); + rr = setsockopt(nnetfd, SOL_SOCKET, SO_SNDBUF, &o_sndbuf, sizeof o_sndbuf); +#endif + + /* fill in all the right sockaddr crud */ + lclend->sin_family = AF_INET; + +/* fill in all the right sockaddr crud */ + lclend->sin_family = AF_INET; + remend->sin_family = AF_INET; + +/* if lad/lp, do appropriate binding */ + if (lad) + memcpy (&lclend->sin_addr.s_addr, lad, sizeof (IA)); + if (lp) + lclend->sin_port = htons (lp); + rr = 0; + if (lad || lp) { + x = (int) lp; +/* try a few times for the local bind, a la ftp-data-port... */ + for (y = 4; y > 0; y--) { + rr = bind (nnetfd, (SA *)lclend, sizeof (SA)); + if (rr == 0) + break; + if (errno != EADDRINUSE) + break; + else { + holler ("retrying local %s:%d", inet_ntoa (lclend->sin_addr), lp); + sleep (2); + errno = 0; /* clear from sleep */ + } /* if EADDRINUSE */ + } /* for y counter */ + } /* if lad or lp */ + if (rr) + bail ("Can't grab %s:%d with bind", + inet_ntoa(lclend->sin_addr), lp); + + if (o_listen) + return (nnetfd); /* thanks, that's all for today */ + + memcpy (&remend->sin_addr.s_addr, rad, sizeof (IA)); + remend->sin_port = htons (rp); + +/* rough format of LSRR option and explanation of weirdness. +Option comes after IP-hdr dest addr in packet, padded to *4, and ihl > 5. +IHL is multiples of 4, i.e. real len = ip_hl << 2. + type 131 1 ; 0x83: copied, option class 0, number 3 + len 1 ; of *whole* option! + pointer 1 ; nxt-hop-addr; 1-relative, not 0-relative + addrlist... var ; 4 bytes per hop-addr + pad-to-32 var ; ones, i.e. "NOP" + +If we want to route A -> B via hops C and D, we must add C, D, *and* B to the +options list. Why? Because when we hand the kernel A -> B with list C, D, B +the "send shuffle" inside the kernel changes it into A -> C with list D, B and +the outbound packet gets sent to C. If B wasn't also in the hops list, the +final destination would have been lost at this point. + +When C gets the packet, it changes it to A -> D with list C', B where C' is +the interface address that C used to forward the packet. This "records" the +route hop from B's point of view, i.e. which address points "toward" B. This +is to make B better able to return the packets. The pointer gets bumped by 4, +so that D does the right thing instead of trying to forward back to C. + +When B finally gets the packet, it sees that the pointer is at the end of the +LSRR list and is thus "completed". B will then try to use the packet instead +of forwarding it, i.e. deliver it up to some application. + +Note that by moving the pointer yourself, you could send the traffic directly +to B but have it return via your preconstructed source-route. Playing with +this and watching "tcpdump -v" is the best way to understand what's going on. + +Only works for TCP in BSD-flavor kernels. UDP is a loss; udp_input calls +stripoptions() early on, and the code to save the srcrt is notdef'ed. +Linux is also still a loss at 1.3.x it looks like; the lsrr code is { }... +*/ + +/* if any -g arguments were given, set up source-routing. We hit this after + the gates are all looked up and ready to rock, any -G pointer is set, + and gatesidx is now the *number* of hops */ + if (gatesidx) { /* if we wanted any srcrt hops ... */ +/* don't even bother compiling if we can't do IP options here! */ +#ifdef IP_OPTIONS + if (! optbuf) { /* and don't already *have* a srcrt set */ + char * opp; /* then do all this setup hair */ + optbuf = Hmalloc (48); + opp = optbuf; + *opp++ = IPOPT_LSRR; /* option */ + *opp++ = (char) + (((gatesidx + 1) * sizeof (IA)) + 3) & 0xff; /* length */ + *opp++ = gatesptr; /* pointer */ +/* opp now points at first hop addr -- insert the intermediate gateways */ + for ( x = 0; x < gatesidx; x++) { + memcpy (opp, gates[x]->iaddrs, sizeof (IA)); + opp += sizeof (IA); + } +/* and tack the final destination on the end [needed!] */ + memcpy (opp, rad, sizeof (IA)); + opp += sizeof (IA); + *opp = IPOPT_NOP; /* alignment filler */ + } /* if empty optbuf */ +/* calculate length of whole option mess, which is (3 + [hops] + [final] + 1), + and apply it [have to do this every time through, of course] */ + x = ((gatesidx + 1) * sizeof (IA)) + 4; + rr = setsockopt (nnetfd, IPPROTO_IP, IP_OPTIONS, optbuf, x); + if (rr == -1) + bail ("srcrt setsockopt fuxored"); +#else /* IP_OPTIONS */ + holler ("Warning: source routing unavailable on this machine, ignoring"); +#endif /* IP_OPTIONS*/ + } /* if gatesidx */ + +/* wrap connect inside a timer, and hit it */ + arm (1, o_wait); + if (setjmp (jbuf) == 0) { + rr = connect (nnetfd, (SA *)remend, sizeof (SA)); + } else { /* setjmp: connect failed... */ + rr = -1; + errno = ETIMEDOUT; /* fake it */ + } + arm (0, 0); + if (rr == 0) + return (nnetfd); + close (nnetfd); /* clean up junked socket FD!! */ + return (-1); +} /* doconnect */ + +/* dolisten : + just like doconnect, and in fact calls a hunk of doconnect, but 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... */ +int dolisten (rad, rp, lad, lp) + IA * rad; + USHORT rp; + IA * lad; + USHORT lp; +{ + register int nnetfd; + register int rr; + HINF * whozis = NULL; + int x; + char * cp; + USHORT z; + errno = 0; + +/* Pass everything off to doconnect, who in o_listen mode just gets a socket */ + nnetfd = doconnect (rad, rp, lad, lp); + if (nnetfd <= 0) + return (-1); + if (o_udpmode) { /* apparently UDP can listen ON */ + if (! lp) /* "port 0", but that's not useful */ + bail ("UDP listen needs -p arg"); + } else { + rr = listen (nnetfd, 1); /* gotta listen() before we can get */ + if (rr < 0) /* our local random port. sheesh. */ + bail ("local listen fuxored"); + } + +/* 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) { + x = sizeof (SA); /* how 'bout getsockNUM instead, pinheads?! */ + rr = getsockname (nnetfd, (SA *) lclend, &x); + if (rr < 0) + holler ("local getsockname failed"); + strcpy (bigbuf_net, "listening on ["); /* buffer reuse... */ + if (lclend->sin_addr.s_addr) + strcat (bigbuf_net, inet_ntoa (lclend->sin_addr)); + else + strcat (bigbuf_net, "any"); + strcat (bigbuf_net, "] %d ..."); + z = ntohs (lclend->sin_port); + holler (bigbuf_net, z); + } /* verbose -- whew!! */ + +/* 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! */ + if (o_udpmode) { + x = sizeof (SA); /* retval for recvfrom */ + arm (2, o_wait); /* might as well timeout this, too */ + if (setjmp (jbuf) == 0) { /* do timeout for initial connect */ + rr = recvfrom /* and here we block... */ + (nnetfd, bigbuf_net, BIGSIZ, MSG_PEEK, (SA *) remend, &x); +Debug (("dolisten/recvfrom ding, rr = %d, netbuf %s ", rr, bigbuf_net)) + } else + goto dol_tmo; /* timeout */ + arm (0, 0); +/* 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? */ + rr = connect (nnetfd, (SA *)remend, sizeof (SA)); + goto whoisit; + } /* o_udpmode */ + +/* fall here for TCP */ + x = sizeof (SA); /* retval for accept */ + arm (2, o_wait); /* wrap this in a timer, too; 0 = forever */ + if (setjmp (jbuf) == 0) { + rr = accept (nnetfd, (SA *)remend, &x); + } else + goto dol_tmo; /* timeout */ + arm (0, 0); + close (nnetfd); /* dump the old socket */ + nnetfd = rr; /* here's our new one */ + +whoisit: + if (rr < 0) + goto dol_err; /* bail out if any errors so far */ + +/* 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. */ +#ifdef IP_OPTIONS + if (! o_verbose) /* if we wont see it, we dont care */ + goto dol_noop; + optbuf = Hmalloc (40); + x = 40; + rr = getsockopt (nnetfd, IPPROTO_IP, IP_OPTIONS, optbuf, &x); + if (rr < 0) + holler ("getsockopt failed"); +Debug (("ipoptions ret len %d", x)) + if (x) { /* we've got options, lessee em... */ + unsigned char * q = (unsigned char *) optbuf; + char * p = bigbuf_net; /* local variables, yuk! */ + char * pp = &bigbuf_net[128]; /* get random space farther out... */ + memset (bigbuf_net, 0, 256); /* clear it all first */ + while (x > 0) { + sprintf (pp, "%2.2x ", *q); /* clumsy, but works: turn into hex */ + strcat (p, pp); /* and build the final string */ + q++; p++; + x--; + } + holler ("IP options: %s", bigbuf_net); + } /* if x, i.e. any options */ +dol_noop: +#endif /* IP_OPTIONS */ + +/* 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. */ + memset (bigbuf_net, 0, 64); + cp = &bigbuf_net[32]; + x = sizeof (SA); + rr = getsockname (nnetfd, (SA *) lclend, &x); + if (rr < 0) + holler ("post-rcv getsockname failed"); + strcpy (cp, inet_ntoa (lclend->sin_addr)); + +/* 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. */ + z = ntohs (remend->sin_port); + strcpy (bigbuf_net, inet_ntoa (remend->sin_addr)); + whozis = gethostpoop (bigbuf_net, o_nflag); + errno = 0; + x = 0; /* use as a flag... */ + if (rad) /* xxx: fix to go down the *list* if we have one? */ + if (memcmp (rad, whozis->iaddrs, sizeof (SA))) + x = 1; + if (rp) + if (z != rp) + x = 1; + if (x) /* guilty! */ + bail ("invalid connection to [%s] from %s [%s] %d", + cp, whozis->name, whozis->addrs[0], z); + holler ("connect to [%s] from %s [%s] %d", /* oh, you're okay.. */ + cp, whozis->name, whozis->addrs[0], z); + return (nnetfd); /* open! */ + +dol_tmo: + errno = ETIMEDOUT; /* fake it */ +dol_err: + close (nnetfd); + return (-1); +} /* dolisten */ + +/* 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. */ +udptest (fd, where) + int fd; + IA * where; +{ + register int rr; + + rr = write (fd, bigbuf_in, 1); + if (rr != 1) + holler ("udptest first write failed?! errno %d", errno); + if (o_wait) + sleep (o_wait); + 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. */ + o_udpmode = 0; /* so doconnect does TCP this time */ +/* 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 = doconnect (where, SLEAZE_PORT, 0, 0); + if (rr > 0) + close (rr); /* in case it *did* open */ + o_wait = 0; /* reset it */ + o_udpmode++; /* we *are* still doing UDP, right? */ + } /* if o_wait */ + errno = 0; /* clear from sleep */ + rr = write (fd, bigbuf_in, 1); + if (rr == 1) /* if write error, no UDP listener */ + return (fd); + close (fd); /* use it or lose it! */ + return (-1); +} /* udptest */ + +/* 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... */ +void oprint (which, buf, n) + int which; + char * buf; + int n; +{ + int bc; /* in buffer count */ + int obc; /* current "global" offset */ + int soc; /* stage write count */ + register unsigned char * p; /* main buf ptr; m.b. unsigned here */ + register unsigned char * op; /* out hexdump ptr */ + register unsigned char * a; /* out asc-dump ptr */ + register int x; + register unsigned int y; + + if (! ofd) + bail ("oprint called with no open fd?!"); + if (n == 0) + return; + + op = stage; + if (which) { + *op = '<'; + obc = wrote_out; /* use the globals! */ + } else { + *op = '>'; + obc = wrote_net; + } + op++; /* preload "direction" */ + *op = ' '; + p = (unsigned char *) buf; + bc = n; + stage[59] = '#'; /* preload separator */ + stage[60] = ' '; + + while (bc) { /* for chunk-o-data ... */ + x = 16; + soc = 78; /* len of whole formatted line */ + if (bc < x) { + soc = soc - 16 + bc; /* fiddle for however much is left */ + x = (bc * 3) + 11; /* 2 digits + space per, after D & offset */ + op = &stage[x]; + x = 16 - bc; + while (x) { + *op++ = ' '; /* preload filler spaces */ + *op++ = ' '; + *op++ = ' '; + x--; + } + x = bc; /* re-fix current linecount */ + } /* if bc < x */ + + bc -= x; /* fix wrt current line size */ + sprintf (&stage[2], "%8.8x ", obc); /* xxx: still slow? */ + obc += x; /* fix current offset */ + op = &stage[11]; /* where hex starts */ + a = &stage[61]; /* where ascii starts */ + + while (x) { /* for line of dump, however long ... */ + y = (int)(*p >> 4); /* hi half */ + *op = hexnibs[y]; + op++; + y = (int)(*p & 0x0f); /* lo half */ + *op = hexnibs[y]; + op++; + *op = ' '; + op++; + if ((*p > 31) && (*p < 127)) + *a = *p; /* printing */ + else + *a = '.'; /* nonprinting, loose def */ + a++; + p++; + x--; + } /* while x */ + *a = '\n'; /* finish the line */ + x = write (ofd, stage, soc); + if (x < 0) + bail ("ofd write err"); + } /* while bc */ +} /* oprint */ + +#ifdef TELNET +USHORT o_tn = 0; /* global -t option */ + +/* atelnet : + Answer anything that looks like telnet negotiation with don't/won't. + This doesn't modify any data buffers, update the global output count, + or show up in a hexdump -- it just shits into the outgoing stream. + Idea and codebase from Mudge@l0pht.com. */ +void atelnet (buf, size) + unsigned char * buf; /* has to be unsigned here! */ + unsigned int size; +{ + static unsigned char obuf [4]; /* tiny thing to build responses into */ + register int x; + register unsigned char y; + register unsigned char * p; + + y = 0; + p = buf; + x = size; + while (x > 0) { + if (*p != 255) /* IAC? */ + goto notiac; + obuf[0] = 255; + p++; x--; + if ((*p == 251) || (*p == 252)) /* WILL or WONT */ + y = 254; /* -> DONT */ + if ((*p == 253) || (*p == 254)) /* DO or DONT */ + y = 252; /* -> WONT */ + if (y) { + obuf[1] = y; + p++; x--; + obuf[2] = *p; /* copy actual option byte */ + (void) write (netfd, obuf, 3); +/* if one wanted to bump wrote_net or do a hexdump line, here's the place */ + y = 0; + } /* if y */ +notiac: + p++; x--; + } /* while x */ +} /* atelnet */ +#endif /* TELNET */ + +/* readwrite : + handle stdin/stdout/network I/O. Bwahaha!! -- the select loop from hell. + In this instance, return what might become our exit status. */ +int readwrite (fd) + int fd; +{ + register int rr; + register char * zp; /* stdin buf ptr */ + register char * np; /* net-in buf ptr */ + unsigned int rzleft; + unsigned int rnleft; + USHORT netretry; /* net-read retry counter */ + USHORT wretry; /* net-write sanity counter */ + USHORT wfirst; /* one-shot flag to skip first net read */ + +/* if you don't have all this FD_* macro hair in sys/types.h, you'll have to + either find it or do your own bit-bashing: *ding1 |= (1 << fd), etc... */ + if (fd > FD_SETSIZE) { + holler ("Preposterous fd value %d", fd); + return (1); + } + FD_SET (fd, ding1); /* global: the net is open */ + netretry = 2; + wfirst = 0; + rzleft = rnleft = 0; + if (insaved) { + rzleft = insaved; /* preload multi-mode fakeouts */ + zp = bigbuf_in; + wfirst = 1; + if (Single) /* if not scanning, this is a one-off first */ + insaved = 0; /* buffer left over from argv construction, */ + else { + FD_CLR (0, ding1); /* OR we've already got our repeat chunk, */ + close (0); /* so we won't need any more stdin */ + } /* Single */ + } /* insaved */ + if (o_interval) + sleep (o_interval); /* pause *before* sending stuff, too */ + errno = 0; /* clear from sleep, close, whatever */ + +/* and now the big ol' select shoveling loop ... */ + while (FD_ISSET (fd, ding1)) { /* i.e. till the *net* closes! */ + wretry = 8200; /* more than we'll ever hafta write */ + if (wfirst) { /* any saved stdin buffer? */ + wfirst = 0; /* clear flag for the duration */ + goto shovel; /* and go handle it first */ + } + *ding2 = *ding1; /* FD_COPY ain't portable... */ +/* some systems, notably linux, crap into their select timers on return, so + we create a expendable copy and give *that* to select. *Fuck* me ... */ + if (timer1) + memcpy (timer2, timer1, sizeof (struct timeval)); + rr = select (16, ding2, 0, 0, timer2); /* here it is, kiddies */ + if (rr < 0) { + if (errno != EINTR) { /* might have gotten ^Zed, etc ?*/ + holler ("select fuxored"); + close (fd); + return (1); + } + } /* select fuckup */ +/* 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 (! FD_ISSET (0, ding1)) + netretry--; /* we actually try a coupla times. */ + if (! netretry) { + if (o_verbose > 1) /* normally we don't care */ + holler ("net timeout"); + close (fd); + return (0); /* not an error! */ + } + } /* select timeout */ +/* xxx: should we check the exception fds too? The read fds seem to give + us the right info, and none of the examples I found bothered. */ + +/* Ding!! Something arrived, go check all the incoming hoppers, net first */ + if (FD_ISSET (fd, ding2)) { /* net: ding! */ + rr = read (fd, bigbuf_net, BIGSIZ); + if (rr <= 0) { + FD_CLR (fd, ding1); /* net closed, we'll finish up... */ + rzleft = 0; /* can't write anymore: broken pipe */ + } else { + rnleft = rr; + np = bigbuf_net; +#ifdef TELNET + if (o_tn) + atelnet (np, rr); /* fake out telnet stuff */ +#endif /* TELNET */ + } /* if rr */ +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 (FD_ISSET (0, ding2)) { /* stdin: ding! */ + rr = read (0, 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 ... */ + FD_CLR (0, ding1); /* disable and close stdin */ + close (0); + } else { + rzleft = rr; + zp = bigbuf_in; +/* special case for multi-mode -- we'll want to send this one buffer to every + open TCP port or every UDP attempt, so save its size and clean up stdin */ + if (! Single) { /* we might be scanning... */ + insaved = rr; /* save len */ + FD_CLR (0, ding1); /* disable further junk from stdin */ + close (0); /* really, I mean it */ + } /* Single */ + } /* if rr/read */ + } /* 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. */ + +/* sanity check. Works because they're both unsigned... */ + if ((rzleft > 8200) || (rnleft > 8200)) { + holler ("Bogus buffers: %d, %d", rzleft, rnleft); + rzleft = rnleft = 0; + } +/* net write retries sometimes happen on UDP connections */ + if (! wretry) { /* is something hung? */ + holler ("too many output retries"); + return (1); + } + if (rnleft) { + rr = write (1, np, rnleft); + if (rr > 0) { + if (o_wfile) + oprint (1, np, rr); /* log the stdout */ + np += rr; /* fix up ptrs and whatnot */ + rnleft -= rr; /* will get sanity-checked above */ + 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 (fd, zp, rr); /* one line, or the whole buffer */ + if (rr > 0) { + if (o_wfile) + oprint (0, zp, rr); /* log what got sent */ + 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); + errno = 0; /* clear from sleep */ + continue; /* ...with hairy select loop... */ + } + if ((rzleft) || (rnleft)) { /* shovel that shit till they ain't */ + wretry--; /* none left, and get another load */ + goto shovel; + } + } /* while ding1:netfd is 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 (fd); + return (0); +} /* readwrite */ + +/* main : + now we pull it all together... */ +main (argc, argv) + int argc; + char ** argv; +{ +#ifndef HAVE_GETOPT + extern char * optarg; + extern int optind, optopt; +#endif + register int x; + register char *cp; + HINF * gp; + HINF * whereto = NULL; + HINF * wherefrom = NULL; + IA * ouraddr = NULL; + IA * themaddr = NULL; + USHORT o_lport = 0; + USHORT ourport = 0; + USHORT loport = 0; /* for scanning stuff */ + USHORT hiport = 0; + USHORT curport = 0; + char * randports = NULL; + +#ifdef HAVE_BIND +/* can *you* say "cc -yaddayadda netcat.c -lresolv -l44bsd" on SunLOSs? */ + res_init(); +#endif +/* I was in this barbershop quartet in Skokie IL ... */ +/* round up the usual suspects, i.e. malloc up all the stuff we need */ + lclend = (SAI *) Hmalloc (sizeof (SA)); + remend = (SAI *) Hmalloc (sizeof (SA)); + bigbuf_in = Hmalloc (BIGSIZ); + bigbuf_net = Hmalloc (BIGSIZ); + ding1 = (fd_set *) Hmalloc (sizeof (fd_set)); + ding2 = (fd_set *) Hmalloc (sizeof (fd_set)); + portpoop = (PINF *) Hmalloc (sizeof (PINF)); + + errno = 0; + gatesptr = 4; + h_errno = 0; + +/* catch a signal or two for cleanup */ + signal (SIGINT, catch); + signal (SIGQUIT, catch); + signal (SIGTERM, catch); +/* and suppress others... */ +#ifdef SIGURG + signal (SIGURG, SIG_IGN); +#endif +#ifdef SIGPIPE + signal (SIGPIPE, SIG_IGN); /* important! */ +#endif + +/* if no args given at all, get 'em from stdin, construct an argv, and hand + anything left over to readwrite(). */ + if (argc == 1) { + cp = argv[0]; + argv = (char **) Hmalloc (128 * sizeof (char *)); /* XXX: 128? */ + argv[0] = cp; /* leave old prog name intact */ + cp = Hmalloc (BIGSIZ); + argv[1] = cp; /* head of new arg block */ + fprintf (stderr, "Cmd line: "); + fflush (stderr); /* I dont care if it's unbuffered or not! */ + insaved = read (0, cp, BIGSIZ); /* we're gonna fake fgets() here */ + if (insaved <= 0) + bail ("wrong"); + x = findline (cp, insaved); + if (x) + insaved -= x; /* remaining chunk size to be sent */ + if (insaved) /* which might be zero... */ + memcpy (bigbuf_in, &cp[x], insaved); + cp = strchr (argv[1], '\n'); + if (cp) + *cp = '\0'; + cp = strchr (argv[1], '\r'); /* look for ^M too */ + if (cp) + *cp = '\0'; + +/* find and stash pointers to remaining new "args" */ + cp = argv[1]; + cp++; /* skip past first char */ + x = 2; /* we know argv 0 and 1 already */ + for (; *cp != '\0'; cp++) { + if (*cp == ' ') { + *cp = '\0'; /* smash all spaces */ + continue; + } else { + if (*(cp-1) == '\0') { + argv[x] = cp; + x++; + } + } /* if space */ + } /* for cp */ + argc = x; + } /* if no args given */ + +/* If your shitbox doesn't have getopt, step into the nineties already. */ +/* optarg, optind = next-argv-component [i.e. flag arg]; optopt = last-char */ + while ((x = getopt (argc, argv, "ae:g:G:hi:lno:p:rs:tuvw:z")) != EOF) { +/* Debug (("in go: x now %c, optarg %x optind %d", x, optarg, optind)) */ + switch (x) { + case 'a': + bail ("all-A-records NIY"); + o_alla++; break; +#ifdef GAPING_SECURITY_HOLE + case 'e': /* prog to exec */ + pr00gie = optarg; + break; +#endif + case 'G': /* srcrt gateways pointer val */ + x = atoi (optarg); + if ((x) && (x == (x & 0x1c))) /* mask off bits of fukt values */ + gatesptr = x; + else + bail ("invalid hop pointer %d, must be multiple of 4 <= 28", x); + break; + case 'g': /* srcroute hop[s] */ + if (gatesidx > 8) + bail ("too many -g hops"); + if (gates == NULL) /* eat this, Billy-boy */ + gates = (HINF **) Hmalloc (sizeof (HINF *) * 10); + gp = gethostpoop (optarg, o_nflag); + if (gp) + gates[gatesidx] = gp; + gatesidx++; + break; + case 'h': + errno = 0; +#ifdef HAVE_HELP + helpme(); /* exits by itself */ +#else + bail ("no help available, dork -- RTFS"); +#endif + case 'i': /* line-interval time */ + o_interval = atoi (optarg) & 0xffff; + if (! o_interval) + bail ("invalid interval time %s", optarg); + break; + case 'l': /* listen mode */ + o_listen++; break; + case 'n': /* numeric-only, no DNS lookups */ + o_nflag++; break; + case 'o': /* hexdump log */ + stage = (unsigned char *) optarg; + o_wfile++; break; + case 'p': /* local source port */ + o_lport = getportpoop (optarg, 0); + if (o_lport == 0) + bail ("invalid local port %s", optarg); + break; + case 'r': /* randomize various things */ + o_random++; break; + case 's': /* local source address */ +/* do a full lookup [since everything else goes through the same mill], + unless -n was previously specified. In fact, careful placement of -n can + be useful, so we'll still pass o_nflag here instead of forcing numeric. */ + wherefrom = gethostpoop (optarg, o_nflag); + ouraddr = &wherefrom->iaddrs[0]; + break; +#ifdef TELNET + case 't': /* do telnet fakeout */ + o_tn++; break; +#endif /* TELNET */ + case 'u': /* use UDP */ + o_udpmode++; break; + case 'v': /* verbose */ + o_verbose++; break; + case 'w': /* wait time */ + o_wait = atoi (optarg); + if (o_wait <= 0) + bail ("invalid wait-time %s", optarg); + timer1 = (struct timeval *) Hmalloc (sizeof (struct timeval)); + timer2 = (struct timeval *) Hmalloc (sizeof (struct timeval)); + timer1->tv_sec = o_wait; /* we need two. see readwrite()... */ + break; + case 'z': /* little or no data xfer */ + o_zero++; + break; + default: + errno = 0; + bail ("nc -h for help"); + } /* switch x */ + } /* while getopt */ + +/* other misc initialization */ +Debug (("fd_set size %d", sizeof (*ding1))) /* how big *is* it? */ + FD_SET (0, ding1); /* stdin *is* initially open */ + if (o_random) { + SRAND (time (0)); + randports = Hmalloc (65536); /* big flag array for ports */ + } +#ifdef GAPING_SECURITY_HOLE + if (pr00gie) { + close (0); /* won't need stdin */ + o_wfile = 0; /* -o with -e is meaningless! */ + ofd = 0; + } +#endif /* G_S_H */ + if (o_wfile) { + ofd = open (stage, O_WRONLY | O_CREAT | O_TRUNC, 0664); + if (ofd <= 0) /* must be > extant 0/1/2 */ + bail ("can't open %s", stage); + stage = (unsigned char *) Hmalloc (100); + } + +/* optind is now index of first non -x arg */ +Debug (("after go: x now %c, optarg %x optind %d", x, optarg, optind)) +/* Debug (("optind up to %d at host-arg %s", optind, argv[optind])) */ +/* gonna only use first addr of host-list, like our IQ was normal; if you wanna + get fancy with addresses, look up the list yourself and plug 'em in for now. + unless we finally implement -a, that is. */ + if (argv[optind]) + whereto = gethostpoop (argv[optind], o_nflag); + if (whereto && whereto->iaddrs) + themaddr = &whereto->iaddrs[0]; + if (themaddr) + optind++; /* skip past valid host lookup */ + errno = 0; + h_errno = 0; + +/* Handle listen mode here, and exit afterward. Only does one connect; + this is arguably the right thing to do. A "persistent listen-and-fork" + mode a la inetd has been thought about, but not implemented. A tiny + wrapper script can handle such things... */ + if (o_listen) { + curport = 0; /* rem port *can* be zero here... */ + if (argv[optind]) { /* any rem-port-arg? */ + curport = getportpoop (argv[optind], 0); + if (curport == 0) /* if given, demand correctness */ + bail ("invalid port %s", argv[optind]); + } /* if port-arg */ + netfd = dolisten (themaddr, curport, ouraddr, o_lport); +/* dolisten does its own connect reporting, so we don't holler anything here */ + if (netfd > 0) { +#ifdef GAPING_SECURITY_HOLE + if (pr00gie) /* -e given? */ + doexec (netfd); +#endif /* GAPING_SECURITY_HOLE */ + x = readwrite (netfd); /* it even works with UDP! */ + if (o_verbose > 1) /* normally we don't care */ + holler (wrote_txt, wrote_net, wrote_out); + exit (x); /* "pack out yer trash" */ + } else /* if no netfd */ + bail ("no connection"); + } /* o_listen */ + +/* fall thru to outbound connects. Now we're more picky about args... */ + if (! themaddr) + bail ("no destination"); + if (argv[optind] == NULL) + bail ("no port[s] to connect to"); + if (argv[optind + 1]) /* look ahead: any more port args given? */ + Single = 0; /* multi-mode, case A */ + ourport = o_lport; /* which can be 0 */ + +/* everything from here down is treated as as ports and/or ranges thereof, so + it's all enclosed in this big ol' argv-parsin' loop. Any randomization is + done within each given *range*, but in separate chunks per each succeeding + argument, so we can control the pattern somewhat. */ + while (argv[optind]) { + hiport = loport = 0; + cp = strchr (argv[optind], '-'); /* nn-mm range? */ + if (cp) { + *cp = '\0'; + cp++; + hiport = getportpoop (cp, 0); + if (hiport == 0) + bail ("invalid port %s", cp); + } /* if found a dash */ + loport = getportpoop (argv[optind], 0); + if (loport == 0) + bail ("invalid port %s", argv[optind]); + if (hiport > loport) { /* was it genuinely a range? */ + Single = 0; /* multi-mode, case B */ + curport = hiport; /* start high by default */ + if (o_random) { /* maybe populate the random array */ + loadports (randports, loport, hiport); + curport = nextport (randports); + } + } else /* not a range, including args like "25-25" */ + curport = loport; +Debug (("Single %d, curport %d", Single, curport)) + +/* Now start connecting to these things. curport is already preloaded. */ + while (loport <= curport) { + if ((! o_lport) && (o_random)) { /* -p overrides random local-port */ + ourport = (RAND() & 0xffff); /* random local-bind -- well above */ + if (ourport < 8192) /* resv and any likely listeners??? */ + ourport += 8192; /* if it *still* conflicts, use -s. */ + } + curport = getportpoop (NULL, curport); + netfd = doconnect (themaddr, curport, ouraddr, ourport); +Debug (("netfd %d from port %d to port %d", netfd, ourport, curport)) + if (netfd > 0) + if (o_zero && o_udpmode) /* if UDP scanning... */ + netfd = udptest (netfd, themaddr); + if (netfd > 0) { /* Yow, are we OPEN YET?! */ + x = 0; /* pre-exit status */ + holler ("%s [%s] %d (%s) open", + whereto->name, whereto->addrs[0], curport, portpoop->name); +#ifdef GAPING_SECURITY_HOLE + if (pr00gie) /* exec is valid for outbound, too */ + doexec (netfd); +#endif /* GAPING_SECURITY_HOLE */ + if (! o_zero) + x = readwrite (netfd); /* go shovel shit */ + } else { /* no netfd... */ + x = 1; /* preload exit status for later */ +/* 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 ((Single || (o_verbose > 1)) || (errno != ECONNREFUSED)) + holler ("%s [%s] %d (%s)", + whereto->name, whereto->addrs[0], curport, portpoop->name); + } /* if netfd */ + close (netfd); /* just in case we didn't already */ + if (o_interval) + sleep (o_interval); /* if -i, delay between ports too */ + if (o_random) + curport = nextport (randports); + else + curport--; /* just decrement... */ + } /* while curport within current range */ + optind++; + } /* while remaining port-args -- end of big argv-ports loop*/ + + errno = 0; + if (o_verbose > 1) /* normally we don't care */ + holler (wrote_txt, wrote_net, wrote_out); + if (Single) + exit (x); /* give us status on one connection */ + exit (0); /* otherwise, we're just done */ +} /* main */ + +#ifdef HAVE_HELP /* unless we wanna be *really* cryptic */ +/* helpme : + the obvious */ +helpme() +{ + o_verbose = 1; + holler ("[v1.10]\n\ +connect to somewhere: nc [-options] hostname port[s] [ports] ... \n\ +listen for inbound: nc -l -p port [-options] [hostname] [port]\n\ +options:"); +/* sigh, this necessarily gets messy. And the trailing \ characters may be + interpreted oddly by some compilers, generating or not generating extra + newlines as they bloody please. u-fix... */ +#ifdef GAPING_SECURITY_HOLE /* needs to be separate holler() */ + holler ("\ + -e prog program to exec after connect [dangerous!!]"); +#endif + holler ("\ + -g gateway source-routing hop point[s], up to 8\n\ + -G num source-routing pointer: 4, 8, 12, ...\n\ + -h this cruft\n\ + -i secs delay interval for lines sent, ports scanned\n\ + -l listen mode, for inbound connects\n\ + -n numeric-only IP addresses, no DNS\n\ + -o file hex dump of traffic\n\ + -p port local port number\n\ + -r randomize local and remote ports\n\ + -s addr local source address"); +#ifdef TELNET + holler ("\ + -t answer TELNET negotiation"); +#endif + holler ("\ + -u UDP mode\n\ + -v verbose [use twice to be more verbose]\n\ + -w secs timeout for connects and final net reads\n\ + -z zero-I/O mode [used for scanning]"); + bail ("port numbers can be individual or ranges: lo-hi [inclusive]"); +} /* helpme */ +#endif /* HAVE_HELP */ + +/* None genuine without this seal! _H*/ |