inet_ntop(3p) — Linux manual page

PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

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

PROLOG         top

       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         top

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

SYNOPSIS         top

       #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         top

       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(3p)).  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 one to four hexadecimal digits 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         top

       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         top

       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         top

       None.

APPLICATION USAGE         top

       None.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       The Base Definitions volume of POSIX.1‐2017, arpa_inet.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                     INET_NTOP(3P)

Pages that refer to this page: arpa_inet.h(0p)freeaddrinfo(3p)getnameinfo(3p)