INET_NET(3)            FreeBSD Library Functions Manual            INET_NET(3)

NAME
     inet_net_ntop, inet_net_pton - Internet network number manipulation
     routines

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/socket.h>
     #include <netinet/in.h>
     #include <arpa/inet.h>

     char *
     inet_net_ntop(int af, const void *src, int bits, char *dst, size_t size);

     int
     inet_net_pton(int af, const char *src, void *dst, size_t size);

DESCRIPTION
     The inet_net_ntop() function converts an Internet network number from
     network format (usually a struct in_addr or some other binary form, in
     network byte order) to CIDR presentation format (suitable for external
     display purposes).  The bits argument is the number of bits in src that
     are the network number.  It returns NULL if a system error occurs (in
     which case, errno will have been set), or it returns a pointer to the
     destination string.

     The inet_net_pton() function converts a presentation format Internet
     network number (that is, printable form as held in a character string) to
     network format (usually a struct in_addr or some other internal binary
     representation, in network byte order).  It returns the number of bits
     (either computed based on the class, or specified with /CIDR), or -1 if a
     failure occurred (in which case errno will have been set.  It will be set
     to ENOENT if the Internet network number was not valid).

     The currently supported values for af are AF_INET and AF_INET6.  The size
     argument is the size of the result buffer dst.

NETWORK NUMBERS (IP VERSION 4)
     Internet network numbers may be specified in one of the following forms:

           a.b.c.d/bits
           a.b.c.d
           a.b.c
           a.b
           a

     When four parts are specified, each is interpreted as a byte of data and
     assigned, from left to right, to the four bytes of an Internet network
     number.  Note that when an Internet network number is viewed as a 32-bit
     integer quantity on a system that uses little-endian byte order (such as
     the Intel 386, 486, and Pentium processors) the bytes referred to above
     appear as "d.c.b.a".  That is, little-endian bytes are ordered from right
     to left.

     When a three part number is specified, the last part is interpreted as a
     16-bit quantity and placed in the least significant two bytes of the
     Internet network number.

     When a two part number is supplied, the last part is interpreted as a
     24-bit quantity and placed in the least significant three bytes of the
     Internet network number.

     When only one part is given, the value is stored directly in the Internet
     network number without any byte rearrangement.

     All numbers supplied as "parts" in a `.' notation may be decimal, octal,
     or hexadecimal, as specified in the C language (i.e., a leading 0x or 0X
     implies hexadecimal; otherwise, a leading 0 implies octal; otherwise, the
     number is interpreted as decimal).

SEE ALSO
     byteorder(3), inet(3), networks(5)

HISTORY
     The inet_net_ntop() and inet_net_pton() functions appeared in BIND 4.9.4.

FreeBSD 13.1-RELEASE-p6        November 9, 2021        FreeBSD 13.1-RELEASE-p6