DragonFly On-Line Manual Pages

GETNETENT(3)          DragonFly Library Functions Manual          GETNETENT(3)

NAME
     getnetent, getnetent_r, getnetbyaddr, getnetbyaddr_r, getnetbyname,
     getnetbyname_r, setnetent, endnetent - get network entry

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <netdb.h>

     struct netent *
     getnetent(void);

     int
     getnetent_r(struct netent *ne, char *buffer, size_t buflen,
         struct netent **result, int *h_errnop);

     struct netent *
     getnetbyname(const char *name);

     int
     getnetbyname_r(const char *name, struct netent *ne, char *buffer,
         size_t buflen, struct netent **result, int *h_errnop);

     struct netent *
     getnetbyaddr(uint32_t net, int type);

     int
     getnetbyaddr_r(uint32_t addr, int af, struct netent *ne, char *buffer,
         size_t buflen, struct netent **result, int *h_errnop);

     void
     setnetent(int stayopen);

     void
     endnetent(void);

DESCRIPTION
     The getnetent(), getnetbyname(), and getnetbyaddr() functions each return
     a pointer to an object with the following structure describing an
     internet network.  This structure contains either the information
     obtained from the nameserver, named(8), broken-out fields of a line in
     the network data base /etc/networks, or entries supplied by the yp(8)
     system.  The order of the lookups is controlled by the `networks' entry
     in nsswitch.conf(5).

           struct  netent {
                   char            *n_name;        /* official name of net */
                   char            **n_aliases;    /* alias list */
                   int             n_addrtype;     /* net number type */
                   uint32_t        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; currently only
                 AF_INET.

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

     The getnetent() function reads the next line of the file, opening the
     file if necessary.

     The setnetent() function opens and rewinds the file.  If the stayopen
     flag is non-zero, the net data base will not be closed after each call to
     getnetbyname() or getnetbyaddr().

     The endnetent() function closes the file.

     The getnetbyname() function and getnetbyaddr() sequentially search from
     the beginning of the file until a matching net name or net address and
     type is found, or until EOF is encountered.  The type argument must be
     AF_INET.  Network numbers are supplied in host order.

     The getnetent_r(), getnetbyaddr_r(), and getnetbyname_r() functions are
     reentrant versions of the above functions that take a pointer to a netent
     structure which is used to store state information.  The structure must
     be zero-filled before it is used and should be considered opaque for the
     sake of portability.  These functions also take a pointer to another
     netent structure which is used to store the results of the database
     lookup.

RETURN VALUES
     The getnetent(), getnetbyaddr(), and getnetbyname() functions return a
     pointer to a netent structure on success or a null pointer if end-of-file
     is reached or an error occurs.

     The getnetent_r(), getnetbyaddr_r(), and getnetbyname_r() functions
     return 0 on success or -1 if end-of-file is reached or an error occurs.

FILES
     /etc/networks
     /etc/nsswitch.conf
     /etc/resolv.conf

SEE ALSO
     networks(5)

     RFC 1101

STANDARDS
     The getnetent(), getnetbyaddr(), getnetbyname(), setnetent(), and
     endnetent() functions conform to IEEE Std 1003.1-2004 ("POSIX.1").

     The getnetent_r(), getnetbyaddr_r(), and getnetbyname_r() functions are
     not currently standardized.

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

     The getnetent_r(), getnetbyaddr_r(), and getnetbyname_r() functions
     appeared in DragonFly 2.1.

BUGS
     The data space used by these functions is thread-specific; 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.

DragonFly 5.9-DEVELOPMENT         May 6, 2019        DragonFly 5.9-DEVELOPMENT