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# inet_net

    INET_NET(3)             System Library Functions Manual            INET_NET(3)

    NAME
         inet_net_ntop, inet_net_pton - Internet network number manipulation rou-
         tines

    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).  bits is the number of bits in src that are the net-
         work 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 net-
         work 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.  size 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 convenient 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; other-
         wise, the number is interpreted as decimal).

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

    HISTORY
         The inet_net_ntop and inet_net_pton functions first appeared in BIND
         4.9.4.

    BSD                              June 18, 1997                             BSD

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