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GETNETENT(3) Linux Programmer's Manual GETNETENT(3)

NAME

     getnetent,  getnetbyname, getnetbyaddr, setnetent, endnetent - get net-
     work entry

SYNOPSIS

     #include <netdb.h>

     struct netent *getnetent(void);

     struct netent *getnetbyname(const char *name);

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

     void setnetent(int stayopen);

     void endnetent(void);

DESCRIPTION

     The getnetent() function reads the next entry from the  networks  data-
     base  and  returns  a netent structure containing the broken-out fields
     from the entry.  A connection is opened to the database if necessary.

     The getnetbyname() function returns a netent structure  for  the  entry
     from the database that matches the network name.

     The  getnetbyaddr()  function  returns a netent structure for the entry
     from the database that matches the network number  net  of  type  type.
     The net argument must be in host byte order.

     The  setnetent()  function opens a connection to the database, and sets
     the next entry to the first entry.  If stayopen is  nonzero,  then  the
     connection  to  the database will not be closed between calls to one of
     the getnet*() functions.

     The endnetent() function closes the connection to the database.

     The netent structure is defined in <netdb.h> as follows:

         struct netent {
             char      *n_name;     /* official network name */
             char     **n_aliases;  /* alias list */
             int        n_addrtype; /* net address type */
             uint32_t   n_net;      /* network number */ }

     The members of the netent structure are:

     n_name The official name of the network.

     n_aliases
            A NULL-terminated list of alternative names for the network.

     n_addrtype
            The type of the network number; always AF_INET.

     n_net  The network number in host byte order.

RETURN VALUE

     The getnetent(), getnetbyname() and getnetbyaddr() functions  return  a
     pointer  to  a statically allocated netent structure, or a null pointer
     if an error occurs or the end of the file is reached.

FILES

     /etc/networks
            networks database file

ATTRIBUTES

     For  an  explanation  of  the  terms  used   in   this   section,   see
     attributes(7).

     +---------------+---------------+---------------------------+
     |Interface      | Attribute     | Value                     |
     +---------------+---------------+---------------------------+
     |getnetent()    | Thread safety | MT-Unsafe race:netent     |
     |               |               | race:netentbuf env locale |
     +---------------+---------------+---------------------------+
     |getnetbyname() | Thread safety | MT-Unsafe race:netbyname  |
     |               |               | env locale                |
     +---------------+---------------+---------------------------+
     |getnetbyaddr() | Thread safety | MT-Unsafe race:netbyaddr  |
     |               |               | locale                    |
     +---------------+---------------+---------------------------+
     |setnetent(),   | Thread safety | MT-Unsafe race:netent env |
     |endnetent()    |               | locale                    |
     +---------------+---------------+---------------------------+
     In  the above table, netent in race:netent signifies that if any of the
     functions setnetent(), getnetent(), or endnetent() are used in parallel
     in different threads of a program, then data races could occur.

CONFORMING TO

     POSIX.1-2001, POSIX.1-2008, 4.3BSD.

NOTES

     In glibc versions before 2.2, the net argument of getnetbyaddr() was of
     type long.