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netcat.c
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// for license see license.txt
/* Netcat 1.00 951010
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:
main:
todo:
more of the portability swamp, and an updated generic.h
frontend progs to generate various packets, raw or otherwise...
char-mode [cbreak, fcntl-unbuffered, etc...]
connect-to-all-A-records hack
bluesky:
RAW mode!
backend progs to grab a pty and look like a real telnetd?!
*/
#include "generic.h" /* same as with L5, skey, etc */
#ifdef WIN32
#pragma comment(lib, "ws2_32") /* winsock support */
#endif
/* conditional includes -- a very messy section: */
/* #undef _POSIX_SOURCE /* might need this for something? */
#define HAVE_BIND /* XXX -- for now, see below... */
//#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> /* xxx: or does it live in sys/ ?? */
#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! */
#ifdef WIN32
#define FD_SETSIZE 64 /* WIN32 does this as an array not a bitfield and it likes 64 */
#else
#define FD_SETSIZE 16 /* <-- this'll give us a long anyways, wtf */
#endif
#include <sys/types.h> /* *now* do it. Sigh, this is broken */
#include <assert.h>
#ifdef WIN32
#undef HAVE_RANDOM
#undef IP_OPTIONS
#undef SO_REUSEPORT
#include <windows.h>
#endif
#ifdef HAVE_RANDOM
#define SRAND srandom
#define RAND random
#else
#define SRAND srand
#define RAND rand
#endif /* HAVE_RANDOM */
/* xxx: these are rsh leftovers, move to new generic.h */
/* will we even need any nonblocking shit? Doubt it. */
/* get FIONBIO from sys/filio.h, so what if it is a compatibility feature */
/* #include <sys/filio.h> */
/*
#include <sys/ioctl.h>
#include <sys/file.h>
*/
/* includes: */
#ifdef WIN32
#include "getopt.h"
//C++: sleep() obsolete... so what's its successor?
//https://forums.techguy.org/threads/c-sleep-obsolete-so-whats-its-successor.220086/
//#define sleep _sleep
#define sleep Sleep
//2020-03-0
//dadeniji conditional define strcasecmp
#ifndef strcasecmp
#define strcasecmp strcmpi
#endif
#define EADDRINUSE WSAEADDRINUSE
#define ETIMEDOUT WSAETIMEDOUT
#define ECONNREFUSED WSAECONNREFUSED
#endif
#ifndef WIN32
#include <sys/time.h> /* timeval, time_t */
#else
#include <time.h>
#endif
#include <setjmp.h> /* jmp_buf et al */
#ifndef WIN32
#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 */
#else
#include <fcntl.h>
#include <io.h>
#include <conio.h>
//#include <winsock2.h>
#endif
#include <stdio.h>
#include <string.h> /* strcpy, strchr, yadda yadda */
#include <errno.h>
#include <signal.h>
/* 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 */
#define SMALLSIZ 256 /* small buffers, hostnames, etc */
#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";
#ifndef WIN32
#ifdef HAVE_BIND
extern int h_errno;
#endif
#endif
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 */
#ifdef WIN32
char *setsockopt_c;
int nnetfd;
#endif
/* 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;
USHORT o_crlf = 0;
/* Debug macro: squirt whatever to stderr 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: */
int helpme(); /* oop */
#ifdef WIN32
/* res_init
winsock needs to be initialized. Might as well do it as the res_init
call for Win32 */
void res_init()
{
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD(1, 1);
err = WSAStartup(wVersionRequested, &wsaData);
if (err != 0)
/* Tell the user that we couldn't find a useable */
/* winsock.dll. */
return;
/* Confirm that the Windows Sockets DLL supports 1.1.*/
/* Note that if the DLL supports versions greater */
/* than 1.1 in addition to 1.1, it will still return */
/* 1.1 in wVersion since that is the version we */
/* requested. */
if (LOBYTE(wsaData.wVersion) != 1 ||
HIBYTE(wsaData.wVersion) != 1)
{
/* Tell the user that we couldn't find a useable */
/* winsock.dll. */
WSACleanup();
return;
}
}
/* winsockstr
Windows Sockets cannot report errors through perror() so we need to define
our own error strings to print. Someday all the string should be prettied up.
Prettied the errors I usually get */
char *winsockstr(error) int error;
{
switch (error)
{
case WSAEINTR:
return ("INTR ");
case WSAEBADF:
return ("BADF ");
case WSAEACCES:
return ("ACCES ");
case WSAEFAULT:
return ("FAULT ");
case WSAEINVAL:
return ("INVAL ");
case WSAEMFILE:
return ("MFILE ");
case WSAEWOULDBLOCK:
return ("WOULDBLOCK ");
case WSAEINPROGRESS:
return ("INPROGRESS ");
case WSAEALREADY:
return ("ALREADY ");
case WSAENOTSOCK:
return ("NOTSOCK ");
case WSAEDESTADDRREQ:
return ("DESTADDRREQ ");
case WSAEMSGSIZE:
return ("MSGSIZE ");
case WSAEPROTOTYPE:
return ("PROTOTYPE ");
case WSAENOPROTOOPT:
return ("NOPROTOOPT ");
case WSAEPROTONOSUPPORT:
return ("PROTONOSUPPORT");
case WSAESOCKTNOSUPPORT:
return ("SOCKTNOSUPPORT");
case WSAEOPNOTSUPP:
return ("OPNOTSUPP ");
case WSAEPFNOSUPPORT:
return ("PFNOSUPPORT ");
case WSAEAFNOSUPPORT:
return ("AFNOSUPPORT ");
case WSAEADDRINUSE:
return ("ADDRINUSE ");
case WSAEADDRNOTAVAIL:
return ("ADDRNOTAVAIL ");
case WSAENETDOWN:
return ("NETDOWN ");
case WSAENETUNREACH:
return ("NETUNREACH ");
case WSAENETRESET:
return ("NETRESET ");
case WSAECONNABORTED:
return ("CONNABORTED ");
case WSAECONNRESET:
return ("CONNRESET ");
case WSAENOBUFS:
return ("NOBUFS ");
case WSAEISCONN:
return ("ISCONN ");
case WSAENOTCONN:
return ("NOTCONN ");
case WSAESHUTDOWN:
return ("SHUTDOWN ");
case WSAETOOMANYREFS:
return ("TOOMANYREFS ");
case WSAETIMEDOUT:
return ("TIMEDOUT ");
case WSAECONNREFUSED:
return ("connection refused");
case WSAELOOP:
return ("LOOP ");
case WSAENAMETOOLONG:
return ("NAMETOOLONG ");
case WSAEHOSTDOWN:
return ("HOSTDOWN ");
case WSAEHOSTUNREACH:
return ("HOSTUNREACH ");
case WSAENOTEMPTY:
return ("NOTEMPTY ");
case WSAEPROCLIM:
return ("PROCLIM ");
case WSAEUSERS:
return ("USERS ");
case WSAEDQUOT:
return ("DQUOT ");
case WSAESTALE:
return ("STALE ");
case WSAEREMOTE:
return ("REMOTE ");
case WSAEDISCON:
return ("DISCON ");
case WSASYSNOTREADY:
return ("SYSNOTREADY ");
case WSAVERNOTSUPPORTED:
return ("VERNOTSUPPORTED");
case WSANOTINITIALISED:
return ("NOTINITIALISED ");
case WSAHOST_NOT_FOUND:
return ("HOST_NOT_FOUND ");
case WSATRY_AGAIN:
return ("TRY_AGAIN ");
case WSANO_RECOVERY:
return ("NO_RECOVERY ");
case WSANO_DATA:
return ("NO_DATA ");
default:
return ("unknown socket error");
}
}
#endif
/* 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 WIN32
if (h_errno)
fprintf(stderr, ": %s\n", winsockstr(h_errno));
#else
if (errno)
{ /* this gives funny-looking messages, but */
perror(" "); /* it's more portable than sys_errlist[]... */
} /* xxx: do something better. */
#endif
else
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);
#ifdef WIN32
shutdown(netfd, 0x02); /* Kirby */
closesocket(netfd);
#else
close(netfd);
#endif
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()
{
#ifdef NTFIXTHIS
signal(SIGALRM, SIG_IGN);
alarm(0);
#endif
if (jval == 0)
bail("spurious timer interrupt!");
longjmp(jbuf, jval);
}
UINT theTimer;
/* arm :
set the timer. Zero secs arg means unarm */
void arm(num, secs) unsigned int num;
unsigned int secs;
{
#ifdef WIN32
HANDLE stdhnd;
stdhnd = GetStdHandle(STD_OUTPUT_HANDLE);
#ifdef DEBUG
if (stdhnd != INVALID_HANDLE_VALUE)
printf("handle is %ld\n", stdhnd);
else
printf("failed to get stdhndl\n");
#endif
#else
if (secs == 0)
{ /* reset */
signal(SIGALRM, SIG_IGN);
alarm(0);
jval = 0;
}
else
{ /* set */
signal(SIGALRM, tmtravel);
alarm(secs);
jval = num;
} /* if secs */
#endif /* WIN32 */
} /* 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;
#ifndef WIN32
h_errno = 0;
#endif
/* 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;
#ifndef WIN32
h_errno = 0;
#endif
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 */
/* XXX: h_errno only if BIND? look up how telnet deals with this */
bail("%s: forward host lookup failed: h_errno %d", name, h_errno);
strncpy(poop->name, hostent->h_name, sizeof(poop->name));
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: h_errno %d",
poop->addrs[x], h_errno);
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: h_errno %d", name, h_errno);
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: h_errno %d",
poop->name, h_errno);
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. */
#ifndef WIN32
h_errno = 0;
#endif
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... */
USHORT getportpoop(pstring, pnum) char *pstring;
unsigned int pnum;
{
struct servent *servent;
#ifndef WIN32
register int x;
register int y;
#else
u_short x;
u_short y;
#endif
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 */
#ifdef WIN32
BOOL doexec(SOCKET ClientSocket); // this is in doexec.c
#else
/* 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 */
#ifdef WIN32
shutdown(fd, SD_BOTH); /* Kirby */
closesocket(fd);
#else
close(fd); /* is apparently crucial; this is */
#endif
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
#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;
{
#ifndef WIN32
register int nnetfd;
#endif
register int rr;
int x, y;
errno = 0;
#ifdef WIN32
WSASetLastError(0);
#endif
/* grab a socket; set opts */
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) /* might *be* zero if stdin was closed! */
nnetfd = dup(nnetfd); /* so fix it. Leave the old 0 hanging. */
#ifdef WIN32
rr = setsockopt(nnetfd, SOL_SOCKET, SO_REUSEADDR, (const char FAR *)setsockopt_c, sizeof(setsockopt_c));
#else
x = 1;
rr = setsockopt(nnetfd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof(x));
#endif
if (rr == -1)
holler("nnetfd reuseaddr failed"); /* ??? */
#ifdef SO_REUSEPORT /* doesnt exist everywhere... */
#ifdef WIN32
rr = setsockopt(nnetfd, SOL_SOCKET, SO_REUSEPORT, &c, sizeof(c));
#else
rr = setsockopt(nnetfd, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x));
#endif
if (rr == -1)
holler("nnetfd reuseport failed"); /* ??? */
#endif
/* 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(1);
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 */
#ifndef WIN32
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));