getnetent

GETNETENT(3)                Library Functions Manual              GETNETENT(3)

NAME
     getnetent, getnetbyaddr, getnetbyname, setnetent, endnetent — get
     networks entry

SYNOPSIS
     #include <netdb.h>

     struct netent *
     getnetent();

     struct netent *
     getnetbyname(char name);;

     struct netent *
     getnetbyaddr(unsigned long net, int type);;

     void
     setnetent(int stayopen);;

     void
     endnetent();

DESCRIPTION
     The getnetent(), getnetbyname(), and getnetbyaddr() subroutines each
     return a pointer to an object with the following structure containing the
     broken-out fields of a line in the networks database.

           struct  netent {
                   char    *n_name;        /* official name of net */
                   char    **n_aliases;    /* alias list */
                   int     n_addrtype;     /* net number type */
                   long    n_net;          /* net number */
           };

     The members of this structure are:

     n_name      The official name of the network.

     n_aliases   A zero-terminated list of alternate names for the network.

     n_addrtype  The type of the network number returned: AF_INET.

     n_net       The network number.  Network numbers are returned in machine
                 byte order.

     If the stayopen flag on a setnetent() subroutine is NULL, the networks
     database is opened.  Otherwise, the setnetent() has the effect of
     rewinding the networks database.  The endnetent() subroutine may be
     called to close the networks database when processing is complete.

     The getnetent() subroutine simply reads the next line while
     getnetbyname() and getnetbyaddr() search until a matching name or net
     number is found (or until EOF is encountered).  The type must be AF_INET.
     The getnetent() subroutine keeps a pointer in the database, allowing
     successive calls to be used to search the entire file.

     Before a while loop using getnetent(), a call to setnetent() must be made
     in order to perform initialization; a call to endnetent() must be used
     after the loop.  Both getnetbyname() and getnetbyaddr() make calls to
     setnetent() and endnetent().

FILES
     /etc/networks

DIAGNOSTICS
     Null pointer (0) returned on EOF or error.

SEE ALSO
     networks(5), RFC 1101.

HISTORY
     The getnetent(), getnetbyaddr(), getnetbyname(), setnetent(), and
     endnetent() functions appeared in 4.2BSD.

BUGS
     The data space used by these functions is static; if future use requires
     the data, it should be copied before any subsequent calls to these
     functions overwrite it.  Only Internet network numbers are currently
     understood.  Expecting network numbers to fit in no more than 32 bits is
     probably naive.

4th Berkeley Distribution        May 20, 1996        4th Berkeley Distribution