percona-xtrabackup-8.0.14/sql/item_inetfunc.cc

/* Copyright (c) 2011, 2019, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include "sql/item_inetfunc.h"

#include "my_config.h"

#include <stdio.h>
#include <string.h>
#include <sys/types.h>

#include "my_byteorder.h"
#include "my_dbug.h"
#include "my_inttypes.h"
#include "mysql/udf_registration_types.h"
#include "mysqld_error.h"
#include "sql/current_thd.h"  //current_thd
#include "sql/derror.h"       //THD
#include "sql/enum_query_type.h"
#include "sql/item.h"
#include "sql/sql_error.h"
#include "sql_string.h"

#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif

///////////////////////////////////////////////////////////////////////////

static const int IN_ADDR_SIZE = sizeof(in_addr);
static const int IN6_ADDR_SIZE = sizeof(in6_addr);
static const int IN6_ADDR_NUM_WORDS = IN6_ADDR_SIZE / 2;

static const char HEX_DIGITS[] = "0123456789abcdef";

///////////////////////////////////////////////////////////////////////////

longlong Item_func_inet_aton::val_int() {
  DBUG_ASSERT(fixed);
  DBUG_ASSERT(arg_count == 1);
  null_value = true;

  uint byte_result = 0;
  ulonglong result = 0;
  const char *p, *end;
  char c = '.';  // we mark c to indicate invalid IP in case length is 0
  char buff[36];
  int dot_count = 0;

  String tmp(buff, sizeof(buff), &my_charset_latin1);
  String *s = args[0]->val_str_ascii(&tmp);

  if (!s)  // If NULL input value, don't emit warning
    return 0;

  p = s->ptr();
  end = p + s->length();
  while (p < end) {
    c = *p++;
    int digit = (int)(c - '0');
    if (digit >= 0 && digit <= 9) {
      byte_result = byte_result * 10 + digit;
      if (byte_result > 255) goto err;  // Wrong address
    } else if (c == '.') {
      dot_count++;
      result = (result << 8) + (ulonglong)byte_result;
      byte_result = 0;
    } else
      goto err;  // Invalid character
  }
  if (c != '.')  // IP number can't end on '.'
  {
    /*
      Attempt to support short forms of IP-addresses. It's however pretty
      basic one comparing to the BSD support.
      Examples:
        127     -> 0.0.0.127
        127.255 -> 127.0.0.255
        127.256 -> NULL (should have been 127.0.1.0)
        127.2.1 -> 127.2.0.1
    */
    switch (dot_count) {
      case 1:
        result <<= 8; /* Fall through */
      case 2:
        result <<= 8; /* Fall through */
    }
    if (dot_count > 3)  // Too many groups
      goto err;
    null_value = false;
    return (result << 8) + (ulonglong)byte_result;
  }

err:
  char buf[256];
  String err(buf, sizeof(buf), system_charset_info);
  err.length(0);
  args[0]->print(current_thd, &err, QT_NO_DATA_EXPANSION);
  push_warning_printf(current_thd, Sql_condition::SL_WARNING,
                      ER_WRONG_VALUE_FOR_TYPE,
                      ER_THD(current_thd, ER_WRONG_VALUE_FOR_TYPE), "string",
                      err.c_ptr_safe(), func_name());

  return 0;
}

///////////////////////////////////////////////////////////////////////////

String *Item_func_inet_ntoa::val_str(String *str) {
  DBUG_ASSERT(fixed);
  DBUG_ASSERT(arg_count == 1);
  null_value = true;
  ulonglong n = (ulonglong)args[0]->val_int();

  /*
    We do not know if args[0] is NULL until we have called
    some val function on it if args[0] is not a constant!

    Also return null if n > 255.255.255.255
  */
  if (args[0]->null_value) return nullptr;
  if (n > (ulonglong)4294967295LL) {
    char buf[256];
    String err(buf, sizeof(buf), system_charset_info);
    err.length(0);
    args[0]->print(current_thd, &err, QT_NO_DATA_EXPANSION);
    push_warning_printf(current_thd, Sql_condition::SL_WARNING,
                        ER_WRONG_VALUE_FOR_TYPE,
                        ER_THD(current_thd, ER_WRONG_VALUE_FOR_TYPE), "integer",
                        err.c_ptr_safe(), func_name());
    return nullptr;
  }
  null_value = false;

  str->set_charset(collation.collation);
  str->length(0);

  uchar buf[8];
  int4store(buf, static_cast<uint32>(n));

  /* Now we can assume little endian. */

  char num[4];
  num[3] = '.';

  for (uchar *p = buf + 4; p-- > buf;) {
    uint c = *p;
    uint n1, n2;   // Try to avoid divisions
    n1 = c / 100;  // 100 digits
    c -= n1 * 100;
    n2 = c / 10;   // 10 digits
    c -= n2 * 10;  // last digit
    num[0] = (char)n1 + '0';
    num[1] = (char)n2 + '0';
    num[2] = (char)c + '0';
    uint length = (n1 ? 4 : n2 ? 3 : 2);  // Remove pre-zero
    uint dot_length = (p <= buf) ? 1 : 0;

    str->append(num + 4 - length, length - dot_length, &my_charset_latin1);
  }

  return str;
}

///////////////////////////////////////////////////////////////////////////

/**
  Check the function argument, handle errors properly.

  @return The function value.
*/

longlong Item_func_inet_bool_base::val_int() {
  DBUG_ASSERT(fixed);

  if (args[0]->result_type() != STRING_RESULT)  // String argument expected
    return 0;

  String buffer;
  String *arg_str = args[0]->val_str(&buffer);

  if (!arg_str)  // Out-of memory happened. The error has been reported.
    return 0;    // Or: the underlying field is NULL

  return calc_value(arg_str) ? 1 : 0;
}

///////////////////////////////////////////////////////////////////////////

/**
  Check the function argument, handle errors properly.

  @param [out] buffer Buffer for string operations.

  @return The function value.
*/

String *Item_func_inet_str_base::val_str_ascii(String *buffer) {
  DBUG_ASSERT(fixed);
  DBUG_ASSERT(arg_count == 1);
  null_value = true;
  String *arg_str;

  /*
    (1) Out-of-memory happened (the error has been reported),
    or the argument is NULL.
    (2) String argument expected.
  */
  if (!(arg_str = args[0]->val_str(buffer)) ||  // (1)
      args[0]->result_type() != STRING_RESULT)  // (2)
  {
    // NULL value can be checked only after calling a val_* func
    if (args[0]->null_value) return nullptr;
    goto err;
  }

  if (calc_value(arg_str, buffer)) {
    null_value = false;
    return buffer;
  }

err:
  char buf[256];
  String err(buf, sizeof(buf), system_charset_info);
  err.length(0);
  args[0]->print(current_thd, &err, QT_NO_DATA_EXPANSION);
  push_warning_printf(current_thd, Sql_condition::SL_WARNING,
                      ER_WRONG_VALUE_FOR_TYPE,
                      ER_THD(current_thd, ER_WRONG_VALUE_FOR_TYPE), "string",
                      err.c_ptr_safe(), func_name());
  return nullptr;
}

///////////////////////////////////////////////////////////////////////////

/**
  Tries to convert given string to binary IPv4-address representation.
  This is a portable alternative to inet_pton(AF_INET).

  @param      str          String to convert.
  @param      str_length   String length.
  @param[out] ipv4_address Buffer to store IPv4-address.

  @return Completion status.
  @retval false Given string does not represent an IPv4-address.
  @retval true  The string has been converted sucessfully.

  @note The problem with inet_pton() is that it treats leading zeros in
  IPv4-part differently on different platforms.
*/

static bool str_to_ipv4(const char *str, int str_length,
                        in_addr *ipv4_address) {
  if (str_length < 7) {
    DBUG_PRINT("error", ("str_to_ipv4(%.*s): "
                         "invalid IPv4 address: too short.",
                         str_length, str));
    return false;
  }

  if (str_length > 15) {
    DBUG_PRINT("error", ("str_to_ipv4(%.*s): "
                         "invalid IPv4 address: too long.",
                         str_length, str));
    return false;
  }

  unsigned char *ipv4_bytes = (unsigned char *)ipv4_address;
  const char *p = str;
  int byte_value = 0;
  int chars_in_group = 0;
  int dot_count = 0;
  char c = 0;

  while (((p - str) < str_length) && *p) {
    c = *p++;

    if (my_isdigit(&my_charset_latin1, c)) {
      ++chars_in_group;

      if (chars_in_group > 3) {
        DBUG_PRINT("error", ("str_to_ipv4(%.*s): invalid IPv4 address: "
                             "too many characters in a group.",
                             str_length, str));
        return false;
      }

      byte_value = byte_value * 10 + (c - '0');

      if (byte_value > 255) {
        DBUG_PRINT("error", ("str_to_ipv4(%.*s): invalid IPv4 address: "
                             "invalid byte value.",
                             str_length, str));
        return false;
      }
    } else if (c == '.') {
      if (chars_in_group == 0) {
        DBUG_PRINT("error", ("str_to_ipv4(%.*s): invalid IPv4 address: "
                             "too few characters in a group.",
                             str_length, str));
        return false;
      }

      ipv4_bytes[dot_count] = (unsigned char)byte_value;

      ++dot_count;
      byte_value = 0;
      chars_in_group = 0;

      if (dot_count > 3) {
        DBUG_PRINT("error", ("str_to_ipv4(%.*s): invalid IPv4 address: "
                             "too many dots.",
                             str_length, str));
        return false;
      }
    } else {
      DBUG_PRINT("error", ("str_to_ipv4(%.*s): invalid IPv4 address: "
                           "invalid character at pos %d.",
                           str_length, str, (int)(p - str)));
      return false;
    }
  }

  if (c == '.') {
    DBUG_PRINT("error", ("str_to_ipv4(%.*s): invalid IPv4 address: "
                         "ending at '.'.",
                         str_length, str));
    return false;
  }

  if (dot_count != 3) {
    DBUG_PRINT("error", ("str_to_ipv4(%.*s): invalid IPv4 address: "
                         "too few groups.",
                         str_length, str));
    return false;
  }

  ipv4_bytes[3] = (unsigned char)byte_value;

  DBUG_PRINT("info",
             ("str_to_ipv4(%.*s): valid IPv4 address: %d.%d.%d.%d", str_length,
              str, ipv4_bytes[0], ipv4_bytes[1], ipv4_bytes[2], ipv4_bytes[3]));
  return true;
}

///////////////////////////////////////////////////////////////////////////

/**
  Tries to convert given string to binary IPv6-address representation.
  This is a portable alternative to inet_pton(AF_INET6).

  @param      str          String to convert.
  @param      str_length   String length.
  @param[out] ipv6_address Buffer to store IPv6-address.

  @return Completion status.
  @retval false Given string does not represent an IPv6-address.
  @retval true  The string has been converted sucessfully.

  @note The problem with inet_pton() is that it treats leading zeros in
  IPv4-part differently on different platforms.
*/

static bool str_to_ipv6(const char *str, int str_length,
                        in6_addr *ipv6_address) {
  if (str_length < 2) {
    DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: too short.",
                         str_length, str));
    return false;
  }

  if (str_length > 8 * 4 + 7) {
    DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: too long.",
                         str_length, str));
    return false;
  }

  memset(ipv6_address, 0, IN6_ADDR_SIZE);

  const char *p = str;

  if (*p == ':') {
    ++p;

    if (*p != ':') {
      DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                           "can not start with ':x'.",
                           str_length, str));
      return false;
    }
  }

  char *ipv6_bytes = (char *)ipv6_address;
  char *ipv6_bytes_end = ipv6_bytes + IN6_ADDR_SIZE;
  char *dst = ipv6_bytes;
  char *gap_ptr = nullptr;
  const char *group_start_ptr = p;
  int chars_in_group = 0;
  int group_value = 0;

  while (((p - str) < str_length) && *p) {
    char c = *p++;

    if (c == ':') {
      group_start_ptr = p;

      if (!chars_in_group) {
        if (gap_ptr) {
          DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                               "too many gaps(::).",
                               str_length, str));
          return false;
        }

        gap_ptr = dst;
        continue;
      }

      if (((p - str) >= str_length) || !*p) {
        DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                             "ending at ':'.",
                             str_length, str));
        return false;
      }

      if (dst + 2 > ipv6_bytes_end) {
        DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                             "too many groups (1).",
                             str_length, str));
        return false;
      }

      dst[0] = (unsigned char)(group_value >> 8) & 0xff;
      dst[1] = (unsigned char)group_value & 0xff;
      dst += 2;

      chars_in_group = 0;
      group_value = 0;
    } else if (c == '.') {
      if (dst + IN_ADDR_SIZE > ipv6_bytes_end) {
        DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                             "unexpected IPv4-part.",
                             str_length, str));
        return false;
      }

      if (!str_to_ipv4(group_start_ptr, str + str_length - group_start_ptr,
                       (in_addr *)dst)) {
        DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                             "invalid IPv4-part.",
                             str_length, str));
        return false;
      }

      dst += IN_ADDR_SIZE;
      chars_in_group = 0;

      break;
    } else {
      const char *hdp = strchr(HEX_DIGITS, my_tolower(&my_charset_latin1, c));

      if (!hdp) {
        DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                             "invalid character at pos %d.",
                             str_length, str, (int)(p - str)));
        return false;
      }

      if (chars_in_group >= 4) {
        DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                             "too many digits in group.",
                             str_length, str));
        return false;
      }

      group_value <<= 4;
      group_value |= hdp - HEX_DIGITS;

      DBUG_ASSERT(group_value <= 0xffff);

      ++chars_in_group;
    }
  }

  if (chars_in_group > 0) {
    if (dst + 2 > ipv6_bytes_end) {
      DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                           "too many groups (2).",
                           str_length, str));
      return false;
    }

    dst[0] = (unsigned char)(group_value >> 8) & 0xff;
    dst[1] = (unsigned char)group_value & 0xff;
    dst += 2;
  }

  if (gap_ptr) {
    if (dst == ipv6_bytes_end) {
      DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                           "no room for a gap (::).",
                           str_length, str));
      return false;
    }

    size_t bytes_to_move = dst - gap_ptr;

    for (size_t i = 1; i <= bytes_to_move; ++i) {
      ipv6_bytes_end[-(static_cast<ssize_t>(i))] = gap_ptr[bytes_to_move - i];
      gap_ptr[bytes_to_move - i] = 0;
    }

    dst = ipv6_bytes_end;
  }

  if (dst < ipv6_bytes_end) {
    DBUG_PRINT("error", ("str_to_ipv6(%.*s): invalid IPv6 address: "
                         "too few groups.",
                         str_length, str));
    return false;
  }

  return true;
}

///////////////////////////////////////////////////////////////////////////

/**
  Converts IPv4-binary-address to a string. This function is a portable
  alternative to inet_ntop(AF_INET).

  @param[in] ipv4 IPv4-address data (byte array)
  @param[out] str A buffer to store string representation of IPv4-address.
                  It must be at least of INET_ADDRSTRLEN.

  @note The problem with inet_ntop() is that it is available starting from
  Windows Vista, but the minimum supported version is Windows 2000.
*/

static void ipv4_to_str(const in_addr *ipv4, char *str) {
  const unsigned char *ipv4_bytes = (const unsigned char *)ipv4;

  sprintf(str, "%d.%d.%d.%d", ipv4_bytes[0], ipv4_bytes[1], ipv4_bytes[2],
          ipv4_bytes[3]);
}
///////////////////////////////////////////////////////////////////////////

/**
  Converts IPv6-binary-address to a string. This function is a portable
  alternative to inet_ntop(AF_INET6).

  @param[in] ipv6 IPv6-address data (byte array)
  @param[out] str A buffer to store string representation of IPv6-address.
                  It must be at least of INET6_ADDRSTRLEN.

  @note The problem with inet_ntop() is that it is available starting from
  Windows Vista, but out the minimum supported version is Windows 2000.
*/

static void ipv6_to_str(const in6_addr *ipv6, char *str) {
  struct Region {
    int pos;
    int length;
  };

  const unsigned char *ipv6_bytes = (const unsigned char *)ipv6;

  // 1. Translate IPv6-address bytes to words.
  // We can't just cast to short, because it's not guaranteed
  // that sizeof (short) == 2. So, we have to make a copy.

  uint16 ipv6_words[IN6_ADDR_NUM_WORDS];

  for (int i = 0; i < IN6_ADDR_NUM_WORDS; ++i)
    ipv6_words[i] = (ipv6_bytes[2 * i] << 8) + ipv6_bytes[2 * i + 1];

  // 2. Find "the gap" -- longest sequence of zeros in IPv6-address.

  Region gap = {-1, -1};

  {
    Region rg = {-1, -1};

    for (int i = 0; i < IN6_ADDR_NUM_WORDS; ++i) {
      if (ipv6_words[i] != 0) {
        if (rg.pos >= 0) {
          if (rg.length > gap.length) gap = rg;

          rg.pos = -1;
          rg.length = -1;
        }
      } else {
        if (rg.pos >= 0) {
          ++rg.length;
        } else {
          rg.pos = i;
          rg.length = 1;
        }
      }
    }

    if (rg.pos >= 0) {
      if (rg.length > gap.length) gap = rg;
    }
  }

  // 3. Convert binary data to string.

  char *p = str;

  for (int i = 0; i < IN6_ADDR_NUM_WORDS; ++i) {
    if (i == gap.pos) {
      // We're at the gap position. We should put trailing ':' and jump to
      // the end of the gap.

      if (i == 0) {
        // The gap starts from the beginning of the data -- leading ':'
        // should be put additionally.

        *p = ':';
        ++p;
      }

      *p = ':';
      ++p;

      i += gap.length - 1;
    } else if (i == 6 && gap.pos == 0 &&
               (gap.length == 6 ||                            // IPv4-compatible
                (gap.length == 5 && ipv6_words[5] == 0xffff)  // IPv4-mapped
                )) {
      // The data represents either IPv4-compatible or IPv4-mapped address.
      // The IPv6-part (zeros or zeros + ffff) has been already put into
      // the string (str). Now it's time to dump IPv4-part.

      ipv4_to_str((const in_addr *)(ipv6_bytes + 12), p);
      return;
    } else {
      // Usual IPv6-address-field. Print it out using lower-case
      // hex-letters without leading zeros (recommended IPv6-format).
      //
      // If it is not the last field, append closing ':'.

      p += sprintf(p, "%x", ipv6_words[i]);

      if (i != IN6_ADDR_NUM_WORDS - 1) {
        *p = ':';
        ++p;
      }
    }
  }

  *p = 0;
}

///////////////////////////////////////////////////////////////////////////

/**
  Converts IP-address-string to IP-address-data.

  @param       arg    IP-address-string.
  @param [out] buffer Buffer to store IP-address-data.

  @return Completion status.
  @retval false Given string does not represent an IP-address.
  @retval true  The string has been converted sucessfully.
*/

bool Item_func_inet6_aton::calc_value(String *arg, String *buffer) {
  // ipv4-string -> varbinary(4)
  // ipv6-string -> varbinary(16)

  in_addr ipv4_address;
  in6_addr ipv6_address;

  if (str_to_ipv4(arg->ptr(), arg->length(), &ipv4_address)) {
    buffer->length(0);
    buffer->append((char *)&ipv4_address, sizeof(in_addr), &my_charset_bin);

    return true;
  }

  if (str_to_ipv6(arg->ptr(), arg->length(), &ipv6_address)) {
    buffer->length(0);
    buffer->append((char *)&ipv6_address, sizeof(in6_addr), &my_charset_bin);

    return true;
  }

  return false;
}

///////////////////////////////////////////////////////////////////////////

/**
  Converts IP-address-data to IP-address-string.

  @param       arg    IP-address-data.
  @param [out] buffer Buffer to store IP-address-string.

  @return Completion status.
  @retval false The argument does not correspond to IP-address.
  @retval true  The string has been converted sucessfully.
*/

bool Item_func_inet6_ntoa::calc_value(String *arg, String *buffer) {
  if (arg->charset() != &my_charset_bin) return false;

  if ((int)arg->length() == IN_ADDR_SIZE) {
    char str[INET_ADDRSTRLEN];

    ipv4_to_str((const in_addr *)arg->ptr(), str);

    buffer->length(0);
    buffer->append(str, strlen(str), &my_charset_latin1);

    return true;
  } else if ((int)arg->length() == IN6_ADDR_SIZE) {
    char str[INET6_ADDRSTRLEN];

    ipv6_to_str((const in6_addr *)arg->ptr(), str);

    buffer->length(0);
    buffer->append(str, strlen(str), &my_charset_latin1);

    return true;
  }

  DBUG_PRINT("info", ("INET6_NTOA(): varbinary(4) or varbinary(16) expected."));
  return false;
}

///////////////////////////////////////////////////////////////////////////

/**
  Checks if the passed string represents an IPv4-address.

  @param arg The string to check.

  @return Check status.
  @retval false The passed string does not represent an IPv4-address.
  @retval true  The passed string represents an IPv4-address.
*/

bool Item_func_is_ipv4::calc_value(const String *arg) const {
  in_addr ipv4_address;

  return str_to_ipv4(arg->ptr(), arg->length(), &ipv4_address);
}

///////////////////////////////////////////////////////////////////////////

/**
  Checks if the passed string represents an IPv6-address.

  @param arg The string to check.

  @return Check status.
  @retval false The passed string does not represent an IPv6-address.
  @retval true  The passed string represents an IPv6-address.
*/

bool Item_func_is_ipv6::calc_value(const String *arg) const {
  in6_addr ipv6_address;

  return str_to_ipv6(arg->ptr(), arg->length(), &ipv6_address);
}

///////////////////////////////////////////////////////////////////////////

/**
  Checks if the passed IPv6-address is an IPv4-compat IPv6-address.

  @param arg The IPv6-address to check.

  @return Check status.
  @retval false The passed IPv6-address is not an IPv4-compatible IPv6-address.
  @retval true  The passed IPv6-address is an IPv4-compatible IPv6-address.
*/

bool Item_func_is_ipv4_compat::calc_value(const String *arg) const {
  if ((int)arg->length() != IN6_ADDR_SIZE || arg->charset() != &my_charset_bin)
    return false;

  in6_addr addr;
  memcpy(&addr, arg->ptr(), sizeof(addr));
  return IN6_IS_ADDR_V4COMPAT(&addr);
}

///////////////////////////////////////////////////////////////////////////

/**
  Checks if the passed IPv6-address is an IPv4-mapped IPv6-address.

  @param arg The IPv6-address to check.

  @return Check status.
  @retval false The passed IPv6-address is not an IPv4-mapped IPv6-address.
  @retval true  The passed IPv6-address is an IPv4-mapped IPv6-address.
*/

bool Item_func_is_ipv4_mapped::calc_value(const String *arg) const {
  if ((int)arg->length() != IN6_ADDR_SIZE || arg->charset() != &my_charset_bin)
    return false;

  in6_addr addr;
  memcpy(&addr, arg->ptr(), sizeof(addr));
  return IN6_IS_ADDR_V4MAPPED(&addr);
}