
/***************************************************************************
 * nbase_misc.c -- Some small miscelaneous utility/compatability           *
 * functions.                                                              *
 *                                                                         *
 ***********************IMPORTANT NMAP LICENSE TERMS************************
 *                                                                         *
 * The Nmap Security Scanner is (C) 1996-2009 Insecure.Com LLC. Nmap is    *
 * also a registered trademark of Insecure.Com LLC.  This program is free  *
 * software; you may redistribute and/or modify it under the terms of the  *
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 *   not derivative works.)                                                * 
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 *                                                                         *
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 *                                                                         *
 * Source is provided to this software because we believe users have a     *
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 * have been found so far).                                                *
 *                                                                         *
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 * included with Nmap.                                                     *
 *                                                                         *
 ***************************************************************************/

/* $Id: nbase_misc.c 12775 2009-03-31 04:14:45Z fyodor $ */

#include "nbase.h"

#ifndef WIN32
#include <errno.h>
#ifndef errno
extern int errno;
#endif
#else
#include <winsock2.h>
#endif

#include "nbase_ipv6.h"
#include "nbase_crc32ct.h"

#include <assert.h>
#include <fcntl.h>

#ifdef WIN32
#include <conio.h>
#endif

#ifndef INET6_ADDRSTRLEN
#define INET6_ADDRSTRLEN 46
#endif

/* Returns the UNIX/Windows errno-equivalent.  Note that the Windows
   call is socket/networking specific.  The windows error number
   returned is like WSAMSGSIZE, but nbase.h includes #defines to
   correlate many of the common UNIX errors with their closest Windows
   equivalents.  So you can use EMSGSIZE or EINTR. */
int socket_errno() {
#ifdef WIN32
	return WSAGetLastError();
#else
	return errno;
#endif
}

/* We can't just use strerror to get socket errors on Windows because it has
   its own set of error codes: WSACONNRESET not ECONNRESET for example. This
   function will do the right thing on Windows. Call it like
     socket_strerror(socket_errno())
*/
char *socket_strerror(int errnum) {
#ifdef WIN32
	static char buffer[128];

	FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
		0, errnum, 0, buffer, sizeof(buffer), NULL);

	return buffer;
#else
	return strerror(errnum);
#endif
}

/* This function is an easier version of inet_ntop because you don't
   need to pass a dest buffer.  Instead, it returns a static buffer that
   you can use until the function is called again (by the same or another
   thread in the process).  If there is a wierd error (like sslen being
   too short) then NULL will be returned. */
const char *inet_ntop_ez(struct sockaddr_storage *ss, size_t sslen) {

  struct sockaddr_in *sin = (struct sockaddr_in *) ss;
  static char str[INET6_ADDRSTRLEN];
#if HAVE_IPV6
  struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) ss;
#endif

  str[0] = '\0';

  if (sin->sin_family == AF_INET) {
    if (sslen < sizeof(struct sockaddr_in))
      return NULL;
    return inet_ntop(AF_INET, &sin->sin_addr, str, sizeof(str));
  } 
#if HAVE_IPV6
  else if(sin->sin_family == AF_INET6) {
    if (sslen < sizeof(struct sockaddr_in6))
      return NULL;
    return inet_ntop(AF_INET6, &sin6->sin6_addr, str, sizeof(str));
  } 
#endif
  //Some laptops report the ip and address family of disabled wifi cards as null
  //so yes, we will hit this sometimes.
  return NULL;
}

/* Create a new socket inheritable by subprocesses. On non-Windows systems it's
   just a normal socket. */
int inheritable_socket(int af, int style, int protocol) {
#ifdef WIN32
  /* WSASocket is just like socket, except that the sockets it creates are
     inheritable by subprocesses (such as are created by CreateProcess), while
     those created by socket are not. */
  return WSASocket(af, style, protocol, NULL, 0, 0);
#else
  return socket(af, style, protocol);
#endif
}

int unblock_socket(int sd) {
#ifdef WIN32
u_long one = 1;
if(sd != 501) // Hack related to WinIP Raw Socket support
  ioctlsocket (sd, FIONBIO, &one);
#else
int options;
/*Unblock our socket to prevent recvfrom from blocking forever
  on certain target ports. */
options = O_NONBLOCK | fcntl(sd, F_GETFL);
fcntl(sd, F_SETFL, options);
#endif //WIN32
return 1;
}

/* Convert a socket to blocking mode */
int block_socket(int sd) {
#ifdef WIN32
  unsigned long options=0;
  if(sd == 501) return 1;
  ioctlsocket(sd, FIONBIO, &options);
#else
  int options;
  options = (~O_NONBLOCK) & fcntl(sd, F_GETFL);
  fcntl(sd, F_SETFL, options);
#endif

  return 1;
}

/* Converts a time specification string into milliseconds.  If the string
 * is a plain non-negative number, it is considered to already be in
 * milliseconds and is returned.  If it is a number followed by 's' (for
 * seconds), 'm' (minutes), or 'h' (hours), the number is converted to
 * milliseconds and returned.  If it cannot parse the string, -1 is
 * returned instead.
 */
long tval2msecs(char *tspec) {
  long l;
  char *endptr = NULL;
  l = strtol(tspec, &endptr, 10);
  if (l < 0 || !endptr) return -1;
  if (*endptr == '\0') return l;
  if (*endptr == 's' || *endptr == 'S') return l * 1000;
  if ((*endptr == 'm' || *endptr == 'M')) {
    if (*(endptr + 1) == 's' || *(endptr + 1) == 'S') 
      return l;
    return l * 60000;
  }
  if (*endptr == 'h' || *endptr == 'H') return l * 3600000;
  return -1;
}

/* A replacement for select on Windows with an additional hack to allow
 * selecting on stdin (file descriptor 0). Windows select doesn't work
 * with stdin. */
int fselect(int s, fd_set *rmaster, fd_set *wmaster, fd_set *emaster, struct timeval *tv)
{
#ifdef WIN32
    static int stdin_thread_started = 0;
    int fds_ready = 0;
    int iter = -1;
    struct timeval stv;
    int stdtty = _isatty(STDIN_FILENO);
    HANDLE stdinhandle = GetStdHandle(STD_INPUT_HANDLE);
    fd_set rset, wset, eset;

    /* Don't do the lame looping if we're not even looking at stdin */
    if (!FD_ISSET(STDIN_FILENO, rmaster))
        return select(s, rmaster, wmaster, emaster, tv);

    /* This is a hack for Windows, which doesn't allow select()ing on
     * non-sockets (like stdin).  We remove stdin from the fd_set and
     * loop while select()ing on everything else, with a timeout of
     * 125ms.  Then we check if stdin is ready and increment fds_ready
     * and set stdin in rmaster if it looks good.  We just keep looping
     * until we have something or it times out.
     */

    /* nbase_winunix.c has all the nasty details behind checking if
     * stdin has input. It involves a background thread, which we start
     * now if necessary. */
    if (!stdin_thread_started) {
        assert(win_stdin_start_thread() != 0);
        stdin_thread_started = 1;
    }

    FD_CLR(STDIN_FILENO, rmaster);

    if (tv) {
        int usecs = (tv->tv_sec * 1000000) + tv->tv_usec;

        iter = usecs / 125000;

        if (usecs % 125000)
            iter++;
    }

    FD_ZERO(&rset);
    FD_ZERO(&wset);
    FD_ZERO(&eset);

    while (!fds_ready && iter) {
        stv.tv_sec = 0;
        stv.tv_usec = 125000;

        if (rmaster)
            rset = *rmaster;
        if (wmaster)
            wset = *wmaster;
        if (emaster)
            eset = *emaster;

        fds_ready = select(s, &rset, &wset, &eset, &stv);

        if (win_stdin_ready()) {
            FD_SET(STDIN_FILENO, &rset);
            fds_ready++;
        }

        if (tv)
            iter--;
    }

    if (rmaster)
        *rmaster = rset;
    if (wmaster)
        *wmaster = wset;
    if (emaster)
        *emaster = eset;

    return fds_ready;
#else
    return select(s, rmaster, wmaster, emaster, tv);
#endif
}


/*
 * CRC32 Cyclic Redundancy Check
 * simply copied from http://www.ptb.de/de/org/1/11/112/infos/crc16.htm
 * (I don't know why he calls it crc16 there, as it returns a 32-bit result)
 */

/* Table of CRCs of all 8-bit messages. */
static unsigned long crc_table[256];

/* Flag: has the table been computed? Initially false. */
static int crc_table_computed = 0;

/* Make the table for a fast CRC. */
static void make_crc_table(void)
{
  unsigned long c;
  int n, k;

  for (n = 0; n < 256; n++) {
    c = (unsigned long) n;
    for (k = 0; k < 8; k++) {
      if (c & 1) {
        c = 0xedb88320L ^ (c >> 1);
      } else {
        c = c >> 1;
      }
    }
    crc_table[n] = c;
  }
  crc_table_computed = 1;
}

/*
   Update a running crc with the bytes buf[0..len-1] and return
 the updated crc. The crc should be initialized to zero. Pre- and
 post-conditioning (one's complement) is performed within this
 function so it shouldn't be done by the caller. Usage example:

   unsigned long crc = 0L;

   while (read_buffer(buffer, length) != EOF) {
     crc = update_crc(crc, buffer, length);
   }
   if (crc != original_crc) error();
*/
static unsigned long update_crc(unsigned long crc,
                unsigned char *buf, int len)
{
  unsigned long c = crc ^ 0xffffffffL;
  int n;

  if (!crc_table_computed)
    make_crc_table();
  for (n = 0; n < len; n++) {
    c = crc_table[(c ^ buf[n]) & 0xff] ^ (c >> 8);
  }
  return c ^ 0xffffffffL;
}

/* Return the CRC of the bytes buf[0..len-1]. */
unsigned long crc32(unsigned char *buf, int len)
{
  return update_crc(0L, buf, len);
}


/*
 * CRC-32C (Castagnoli) Cyclic Redundancy Check.
 * Taken straight from RFC 4960 (SCTP).
 */

/* Return the CRC-32C of the bytes buf[0..len-1] */
unsigned long crc32c(unsigned char *buf, int len)
{
  int i;
  unsigned long crc32 = ~0L;
  unsigned long result;
  unsigned char byte0, byte1, byte2, byte3;

  for (i = 0; i < len; i++) {
    CRC32C(crc32, buf[i]);
  }

  result = ~crc32;

  /*  result now holds the negated polynomial remainder;
   *  since the table and algorithm is "reflected" [williams95].
   *  That is, result has the same value as if we mapped the message
   *  to a polynomial, computed the host-bit-order polynomial
   *  remainder, performed final negation, then did an end-for-end
   *  bit-reversal.
   *  Note that a 32-bit bit-reversal is identical to four inplace
   *  8-bit reversals followed by an end-for-end byteswap.
   *  In other words, the bytes of each bit are in the right order,
   *  but the bytes have been byteswapped.  So we now do an explicit
   *  byteswap.  On a little-endian machine, this byteswap and
   *  the final ntohl cancel out and could be elided.
   */

  byte0 =  result        & 0xff;
  byte1 = (result >>  8) & 0xff;
  byte2 = (result >> 16) & 0xff;
  byte3 = (result >> 24) & 0xff;
  crc32 = ((byte0 << 24) | (byte1 << 16) | (byte2 <<  8) | byte3);
  return crc32;
}


/*
 * Adler32 Checksum Calculation.
 * Taken straight from RFC 2960 (SCTP).
 */

#define ADLER32_BASE 65521 /* largest prime smaller than 65536 */

/*
 * Update a running Adler-32 checksum with the bytes buf[0..len-1]
 * and return the updated checksum.  The Adler-32 checksum should
 * be initialized to 1.
 */
static unsigned long update_adler32(unsigned long adler,
                                    unsigned char *buf, int len)
{
  unsigned long s1 = adler & 0xffff;
  unsigned long s2 = (adler >> 16) & 0xffff;
  int n;

  for (n = 0; n < len; n++) {
    s1 = (s1 + buf[n]) % ADLER32_BASE;
    s2 = (s2 + s1)     % ADLER32_BASE;
  }
  return (s2 << 16) + s1;
}

/* Return the Adler32 of the bytes buf[0..len-1] */
unsigned long adler32(unsigned char *buf, int len)
{
  return update_adler32(1L, buf, len);
}


