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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.php .



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