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INET_NTOP(3P)              POSIX Programmer's Manual             INET_NTOP(3P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
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 argu-
       ment 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 charac-
       ters 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  for-
       mats  (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. Lead-
           ing  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 sim-
           ply 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 contain-
       ing 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(3P)