NAME

       inet_ntop, inet_pton - convert IPv4 and IPv6 addresses between binary and text form

SYNOPSIS

       #include <arpa/inet.h>

       const char *inet_ntop(int af, const void *restrict src,
              char *restrict dst, socklen_t size);
       int inet_pton(int af, const char *restrict src, void *restrict dst);

DESCRIPTION

       The  inet_ntop()  function  shall convert a numeric address into a text string suitable for presentation.
       The af argument shall specify the family of the address. This can  be  AF_INET   or  AF_INET6.   The  src
       argument points to a buffer holding an IPv4 address if the af argument is AF_INET,  or an IPv6 address if
       the  af  argument  is  AF_INET6;  the address must be in network byte order. The dst argument points to a
       buffer where the function stores the resulting text string; it shall  not  be  NULL.  The  size  argument
       specifies  the  size of this buffer, which shall be large enough to hold the text string (INET_ADDRSTRLEN
       characters for IPv4,    INET6_ADDRSTRLEN characters for IPv6).

       The inet_pton() function shall convert an address in its standard text presentation form into its numeric
       binary form.  The af argument shall specify the family  of  the  address.  The  AF_INET     and  AF_INET6
       address  families  shall  be  supported.  The  src argument points to the string being passed in. The dst
       argument points to a buffer into which the function stores the  numeric  address;  this  shall  be  large
       enough to hold the numeric address (32 bits for AF_INET,  128 bits for AF_INET6).

       If the af argument of inet_pton() is AF_INET, the src string shall be in the standard IPv4 dotted-decimal
       form:

              ddd.ddd.ddd.ddd

       where  "ddd" is a one to three digit decimal number between 0 and 255 (see inet_addr() ). The inet_pton()
       function does not accept other formats (such as the octal numbers, hexadecimal numbers,  and  fewer  than
       four numbers that inet_addr() accepts).

       If  the  af argument of inet_pton() is AF_INET6, the src string shall be in one of the following standard
       IPv6 text forms:

        1. The preferred form is "x:x:x:x:x:x:x:x" , where the 'x' s are the hexadecimal  values  of  the  eight
           16-bit  pieces  of the address. Leading zeros in individual fields can be omitted, but there shall be
           at least one numeral in every field.

        2. A string of contiguous zero fields in the preferred form can be shown as "::" .  The  "::"  can  only
           appear  once  in an address. Unspecified addresses ( "0:0:0:0:0:0:0:0" ) may be represented simply as
           "::" .

        3. A third form that is sometimes more convenient when dealing with a mixed environment of IPv4 and IPv6
           nodes is "x:x:x:x:x:x:d.d.d.d" , where the 'x' s are the hexadecimal values  of  the  six  high-order
           16-bit pieces of the address, and the 'd' s are the decimal values of the four low-order 8-bit pieces
           of the address (standard IPv4 representation).

       Note:  A  more  extensive  description  of the standard representations of IPv6 addresses can be found in
              RFC 2373.

RETURN VALUE

       The inet_ntop() function shall return a  pointer  to  the  buffer  containing  the  text  string  if  the
       conversion succeeds, and NULL otherwise, and set errno to indicate the error.

       The inet_pton() function shall return 1 if the conversion succeeds, with the address pointed to by dst in
       network  byte  order.  It  shall  return 0 if the input is not a valid IPv4 dotted-decimal string    or a
       valid IPv6 address string,  or -1 with errno set to [EAFNOSUPPORT] if the af argument is unknown.

ERRORS

       The inet_ntop() and inet_pton() functions shall fail if:

       EAFNOSUPPORT

              The af argument is invalid.

       ENOSPC The size of the inet_ntop() result buffer is inadequate.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       The Base Definitions volume of IEEE Std 1003.1-2001, <arpa/inet.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc  and  The  Open Group. In the event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                                   2003                                          INET_NTOP(P)