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INET_NET(3)              BSD 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/types.h>
     #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 num-ber. number.
     ber.  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 only value for af currently supported is AF_INET.  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 rightmost two bytes of the Internet network number.  This makes the three part number format conve-nient convenient
     nient for specifying Class B network numbers as ``128.net.host''.

     When a two part number is supplied, the last part is interpreted as a 24-bit quantity and placed in the
     rightmost three bytes of the Internet network number.  This makes the two part number format convenient
     for specifying Class A network numbers as ``net.host''.

     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.

BSD                              June 18, 1997                             BSD