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inet_net_ntop.c
/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1996,1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 *      $PostgreSQL: pgsql/src/backend/utils/adt/inet_net_ntop.c,v 1.24 2006/07/14 16:59:19 tgl Exp $
 */

#if defined(LIBC_SCCS) && !defined(lint)
static const char rcsid[] = "Id: inet_net_ntop.c,v 1.1.2.2 2004/03/09 09:17:27 marka Exp $";
#endif

#include "postgres.h"

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "utils/builtins.h"
#include "utils/inet.h"


#define NS_IN6ADDRSZ 16
#define NS_INT16SZ 2

#ifdef SPRINTF_CHAR
#define SPRINTF(x) strlen(sprintf/**/x)
#else
#define SPRINTF(x) ((size_t)sprintf x)
#endif

static char *inet_net_ntop_ipv4(const u_char *src, int bits,
                           char *dst, size_t size);
static char *inet_cidr_ntop_ipv4(const u_char *src, int bits,
                              char *dst, size_t size);
static char *inet_net_ntop_ipv6(const u_char *src, int bits,
                           char *dst, size_t size);
static char *inet_cidr_ntop_ipv6(const u_char *src, int bits,
                              char *dst, size_t size);

/*
 * char *
 * inet_cidr_ntop(af, src, bits, dst, size)
 *    convert network number from network to presentation format.
 *    generates CIDR style result always.
 * return:
 *    pointer to dst, or NULL if an error occurred (check errno).
 * author:
 *    Paul Vixie (ISC), July 1996
 */
char *
inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size)
{
      switch (af)
      {
            case PGSQL_AF_INET:
                  return (inet_cidr_ntop_ipv4(src, bits, dst, size));
            case PGSQL_AF_INET6:
                  return (inet_cidr_ntop_ipv6(src, bits, dst, size));
            default:
                  errno = EAFNOSUPPORT;
                  return (NULL);
      }
}


/*
 * static char *
 * inet_cidr_ntop_ipv4(src, bits, dst, size)
 *    convert IPv4 network number from network to presentation format.
 *    generates CIDR style result always.
 * return:
 *    pointer to dst, or NULL if an error occurred (check errno).
 * note:
 *    network byte order assumed.  this means 192.5.5.240/28 has
 *    0b11110000 in its fourth octet.
 * author:
 *    Paul Vixie (ISC), July 1996
 */
static char *
inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size)
{
      char     *odst = dst;
      char     *t;
      u_int       m;
      int               b;

      if (bits < 0 || bits > 32)
      {
            errno = EINVAL;
            return (NULL);
      }

      if (bits == 0)
      {
            if (size < sizeof "0")
                  goto emsgsize;
            *dst++ = '0';
            size--;
            *dst = '\0';
      }

      /* Format whole octets. */
      for (b = bits / 8; b > 0; b--)
      {
            if (size <= sizeof "255.")
                  goto emsgsize;
            t = dst;
            dst += SPRINTF((dst, "%u", *src++));
            if (b > 1)
            {
                  *dst++ = '.';
                  *dst = '\0';
            }
            size -= (size_t) (dst - t);
      }

      /* Format partial octet. */
      b = bits % 8;
      if (b > 0)
      {
            if (size <= sizeof ".255")
                  goto emsgsize;
            t = dst;
            if (dst != odst)
                  *dst++ = '.';
            m = ((1 << b) - 1) << (8 - b);
            dst += SPRINTF((dst, "%u", *src & m));
            size -= (size_t) (dst - t);
      }

      /* Format CIDR /width. */
      if (size <= sizeof "/32")
            goto emsgsize;
      dst += SPRINTF((dst, "/%u", bits));
      return (odst);

emsgsize:
      errno = EMSGSIZE;
      return (NULL);
}

/*
 * static char *
 * inet_cidr_ntop_ipv6(src, bits, fakebits, dst, size)
 *    convert IPv6 network number from network to presentation format.
 *    generates CIDR style result always. Picks the shortest representation
 *    unless the IP is really IPv4.
 *    always prints specified number of bits (bits).
 * return:
 *    pointer to dst, or NULL if an error occurred (check errno).
 * note:
 *    network byte order assumed.  this means 192.5.5.240/28 has
 *    0x11110000 in its fourth octet.
 * author:
 *    Vadim Kogan (UCB), June 2001
 *    Original version (IPv4) by Paul Vixie (ISC), July 1996
 */

static char *
inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size)
{
      u_int       m;
      int               b;
      int               p;
      int               zero_s,
                        zero_l,
                        tmp_zero_s,
                        tmp_zero_l;
      int               i;
      int               is_ipv4 = 0;
      unsigned char inbuf[16];
      char        outbuf[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];
      char     *cp;
      int               words;
      u_char         *s;

      if (bits < 0 || bits > 128)
      {
            errno = EINVAL;
            return (NULL);
      }

      cp = outbuf;

      if (bits == 0)
      {
            *cp++ = ':';
            *cp++ = ':';
            *cp = '\0';
      }
      else
      {
            /* Copy src to private buffer.      Zero host part. */
            p = (bits + 7) / 8;
            memcpy(inbuf, src, p);
            memset(inbuf + p, 0, 16 - p);
            b = bits % 8;
            if (b != 0)
            {
                  m = ~0 << (8 - b);
                  inbuf[p - 1] &= m;
            }

            s = inbuf;

            /* how many words need to be displayed in output */
            words = (bits + 15) / 16;
            if (words == 1)
                  words = 2;

            /* Find the longest substring of zero's */
            zero_s = zero_l = tmp_zero_s = tmp_zero_l = 0;
            for (i = 0; i < (words * 2); i += 2)
            {
                  if ((s[i] | s[i + 1]) == 0)
                  {
                        if (tmp_zero_l == 0)
                              tmp_zero_s = i / 2;
                        tmp_zero_l++;
                  }
                  else
                  {
                        if (tmp_zero_l && zero_l < tmp_zero_l)
                        {
                              zero_s = tmp_zero_s;
                              zero_l = tmp_zero_l;
                              tmp_zero_l = 0;
                        }
                  }
            }

            if (tmp_zero_l && zero_l < tmp_zero_l)
            {
                  zero_s = tmp_zero_s;
                  zero_l = tmp_zero_l;
            }

            if (zero_l != words && zero_s == 0 && ((zero_l == 6) ||
                                      ((zero_l == 5 && s[10] == 0xff && s[11] == 0xff) ||
                                       ((zero_l == 7 && s[14] != 0 && s[15] != 1)))))
                  is_ipv4 = 1;

            /* Format whole words. */
            for (p = 0; p < words; p++)
            {
                  if (zero_l != 0 && p >= zero_s && p < zero_s + zero_l)
                  {
                        /* Time to skip some zeros */
                        if (p == zero_s)
                              *cp++ = ':';
                        if (p == words - 1)
                              *cp++ = ':';
                        s++;
                        s++;
                        continue;
                  }

                  if (is_ipv4 && p > 5)
                  {
                        *cp++ = (p == 6) ? ':' : '.';
                        cp += SPRINTF((cp, "%u", *s++));
                        /* we can potentially drop the last octet */
                        if (p != 7 || bits > 120)
                        {
                              *cp++ = '.';
                              cp += SPRINTF((cp, "%u", *s++));
                        }
                  }
                  else
                  {
                        if (cp != outbuf)
                              *cp++ = ':';
                        cp += SPRINTF((cp, "%x", *s * 256 + s[1]));
                        s += 2;
                  }
            }
      }
      /* Format CIDR /width. */
      (void) SPRINTF((cp, "/%u", bits));
      if (strlen(outbuf) + 1 > size)
            goto emsgsize;
      strcpy(dst, outbuf);

      return (dst);

emsgsize:
      errno = EMSGSIZE;
      return (NULL);
}


/*
 * char *
 * inet_net_ntop(af, src, bits, dst, size)
 *    convert host/network address from network to presentation format.
 *    "src"'s size is determined from its "af".
 * return:
 *    pointer to dst, or NULL if an error occurred (check errno).
 * note:
 *    192.5.5.1/28 has a nonzero host part, which means it isn't a network
 *    as called for by inet_net_pton() but it can be a host address with
 *    an included netmask.
 * author:
 *    Paul Vixie (ISC), October 1998
 */
char *
inet_net_ntop(int af, const void *src, int bits, char *dst, size_t size)
{
      switch (af)
      {
            case PGSQL_AF_INET:
                  return (inet_net_ntop_ipv4(src, bits, dst, size));
            case PGSQL_AF_INET6:
                  return (inet_net_ntop_ipv6(src, bits, dst, size));
            default:
                  errno = EAFNOSUPPORT;
                  return (NULL);
      }
}

/*
 * static char *
 * inet_net_ntop_ipv4(src, bits, dst, size)
 *    convert IPv4 network address from network to presentation format.
 *    "src"'s size is determined from its "af".
 * return:
 *    pointer to dst, or NULL if an error occurred (check errno).
 * note:
 *    network byte order assumed.  this means 192.5.5.240/28 has
 *    0b11110000 in its fourth octet.
 * author:
 *    Paul Vixie (ISC), October 1998
 */
static char *
inet_net_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size)
{
      char     *odst = dst;
      char     *t;
      int               len = 4;
      int               b;

      if (bits < 0 || bits > 32)
      {
            errno = EINVAL;
            return (NULL);
      }

      /* Always format all four octets, regardless of mask length. */
      for (b = len; b > 0; b--)
      {
            if (size <= sizeof ".255")
                  goto emsgsize;
            t = dst;
            if (dst != odst)
                  *dst++ = '.';
            dst += SPRINTF((dst, "%u", *src++));
            size -= (size_t) (dst - t);
      }

      /* don't print masklen if 32 bits */
      if (bits != 32)
      {
            if (size <= sizeof "/32")
                  goto emsgsize;
            dst += SPRINTF((dst, "/%u", bits));
      }

      return (odst);

emsgsize:
      errno = EMSGSIZE;
      return (NULL);
}

static int
decoct(const u_char *src, int bytes, char *dst, size_t size)
{
      char     *odst = dst;
      char     *t;
      int               b;

      for (b = 1; b <= bytes; b++)
      {
            if (size <= sizeof "255.")
                  return (0);
            t = dst;
            dst += SPRINTF((dst, "%u", *src++));
            if (b != bytes)
            {
                  *dst++ = '.';
                  *dst = '\0';
            }
            size -= (size_t) (dst - t);
      }
      return (dst - odst);
}

static char *
inet_net_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size)
{
      /*
       * Note that int32_t and int16_t need only be "at least" large enough to
       * contain a value of the specified size.  On some systems, like Crays,
       * there is no such thing as an integer variable with 16 bits. Keep this
       * in mind if you think this function should have been coded to use
       * pointer overlays.  All the world's not a VAX.
       */
      char        tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255/128"];
      char     *tp;
      struct
      {
            int               base,
                              len;
      }                 best, cur;
      u_int       words[NS_IN6ADDRSZ / NS_INT16SZ];
      int               i;

      if ((bits < -1) || (bits > 128))
      {
            errno = EINVAL;
            return (NULL);
      }

      /*
       * Preprocess: Copy the input (bytewise) array into a wordwise array. Find
       * the longest run of 0x00's in src[] for :: shorthanding.
       */
      memset(words, '\0', sizeof words);
      for (i = 0; i < NS_IN6ADDRSZ; i++)
            words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
      best.base = -1;
      cur.base = -1;
      best.len = 0;
      cur.len = 0;
      for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
      {
            if (words[i] == 0)
            {
                  if (cur.base == -1)
                        cur.base = i, cur.len = 1;
                  else
                        cur.len++;
            }
            else
            {
                  if (cur.base != -1)
                  {
                        if (best.base == -1 || cur.len > best.len)
                              best = cur;
                        cur.base = -1;
                  }
            }
      }
      if (cur.base != -1)
      {
            if (best.base == -1 || cur.len > best.len)
                  best = cur;
      }
      if (best.base != -1 && best.len < 2)
            best.base = -1;

      /*
       * Format the result.
       */
      tp = tmp;
      for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
      {
            /* Are we inside the best run of 0x00's? */
            if (best.base != -1 && i >= best.base &&
                  i < (best.base + best.len))
            {
                  if (i == best.base)
                        *tp++ = ':';
                  continue;
            }
            /* Are we following an initial run of 0x00s or any real hex? */
            if (i != 0)
                  *tp++ = ':';
            /* Is this address an encapsulated IPv4? */
            if (i == 6 && best.base == 0 && (best.len == 6 ||
                                                       (best.len == 7 && words[7] != 0x0001) ||
                                                        (best.len == 5 && words[5] == 0xffff)))
            {
                  int               n;

                  n = decoct(src + 12, 4, tp, sizeof tmp - (tp - tmp));
                  if (n == 0)
                  {
                        errno = EMSGSIZE;
                        return (NULL);
                  }
                  tp += strlen(tp);
                  break;
            }
            tp += SPRINTF((tp, "%x", words[i]));
      }

      /* Was it a trailing run of 0x00's? */
      if (best.base != -1 && (best.base + best.len) ==
            (NS_IN6ADDRSZ / NS_INT16SZ))
            *tp++ = ':';
      *tp = '\0';

      if (bits != -1 && bits != 128)
            tp += SPRINTF((tp, "/%u", bits));

      /*
       * Check for overflow, copy, and we're done.
       */
      if ((size_t) (tp - tmp) > size)
      {
            errno = EMSGSIZE;
            return (NULL);
      }
      strcpy(dst, tmp);
      return (dst);
}

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