INET(3N-SVR4)       RISC/os Reference Manual        INET(3N-SVR4)



NAME
     inet: inet_addr, inet_network, inet_makeaddr, inet_lnaof,
          inet_netof, inet_ntoa - Internet address manipulation

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

     unsigned long
     inetaddr(cp)
     char *cp;

     inetnetwork(cp)
     char *cp;

     struct inaddr
     inetmakeaddr(net, lna)
     int net, lna;

     inetlnaof(in)
     struct inaddr in;

     inetnetof(in)
     struct inaddr in;

     char *
     inetntoa(in)
     struct inaddr in;

DESCRIPTION
     The routines inetaddr() and inetnetwork() each interpret
     character strings representing numbers expressed in the
     Internet standard `.'  notation, returning numbers suitable
     for use as Internet addresses and Internet network numbers,
     respectively.  The routine inetmakeaddr() takes an Internet
     network number and a local network address and constructs an
     Internet address from it.  The routines inetnetof() and
     inetlnaof() break apart Internet host addresses, returning
     the network number and local network address part, respec-
     tively.

     The routine inetntoa() returns a pointer to a string in the
     base 256 notation "d.d.d.d" described below.

     All Internet addresses are returned in network order (bytes
     ordered from left to right).  All network numbers and local
     address parts are returned as machine format integer values.

INTERNET ADDRESSES




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INET(3N-SVR4)       RISC/os Reference Manual        INET(3N-SVR4)



     Values specified using the `.'  notation take one of the
     following forms:

          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 address.

     When a three part address is specified, the last part is
     interpreted as a 16-bit quantity and placed in the right
     most two bytes of the network address.  This makes the three
     part address format convenient for specifying Class B net-
     work addresses as 128.net.host.

     When a two part address is supplied, the last part is inter-
     preted as a 24-bit quantity and placed in the right most
     three bytes of the network address.  This makes the two part
     address format convenient for specifying Class A network
     addresses as net.host.

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

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

SEE ALSO
     gethostent(3N), getnetent(3N), hosts(4), networks(4).

DIAGNOSTICS
     The value -1 is returned by inetaddr() and inetnetwork()
     for malformed requests.

BUGS
     The problem of host byte ordering versus network byte order-
     ing is confusing.  A simple way to specify Class C network
     addresses in a manner similar to that for Class B and Class
     A is needed.

     The return value from inetntoa() points to static informa-
     tion which is overwritten in each call.







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