PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

NAME

       endnetent, getnetbyaddr, getnetbyname, getnetent, setnetent — network database functions

SYNOPSIS

       #include <netdb.h>

       void endnetent(void);
       struct netent *getnetbyaddr(uint32_t net, int type);
       struct netent *getnetbyname(const char *name);
       struct netent *getnetent(void);
       void setnetent(int stayopen);

DESCRIPTION

       These functions shall retrieve information about networks. This information is considered to be stored in
       a  database  that  can  be  accessed  sequentially  or  randomly.  The implementation of this database is
       unspecified.

       The setnetent() function shall open and rewind the database. If the stayopen argument  is  non-zero,  the
       connection  to  the  net database shall not be closed after each call to getnetent() (either directly, or
       indirectly through one of the other getnet*() functions), and the implementation  may  maintain  an  open
       file descriptor to the database.

       The  getnetent()  function shall read the next entry of the database, opening and closing a connection to
       the database as necessary.

       The getnetbyaddr() function shall search the database from the beginning, and find the  first  entry  for
       which  the  address  family  specified  by  type matches the n_addrtype member and the network number net
       matches the n_net member, opening and closing a  connection  to  the  database  as  necessary.   The  net
       argument shall be the network number in host byte order.

       The  getnetbyname()  function  shall  search the database from the beginning and find the first entry for
       which the network name specified by name matches the n_name member, opening and closing a  connection  to
       the database as necessary.

       The  getnetbyaddr(),  getnetbyname(),  and  getnetent() functions shall each return a pointer to a netent
       structure, the members of which shall contain the fields of an entry in the network database.

       The endnetent() function shall close the database, releasing any open file descriptor.

       These functions need not be thread-safe.

RETURN VALUE

       Upon successful completion, getnetbyaddr(), getnetbyname(), and getnetent() shall return a pointer  to  a
       netent  structure  if  the  requested  entry was found, and a null pointer if the end of the database was
       reached or the requested entry was not found.  Otherwise, a null pointer shall be returned.

       The application shall not modify the structure to which the return value points, nor  any  storage  areas
       pointed  to  by  pointers  within the structure. The returned pointer, and pointers within the structure,
       might be invalidated or the structure or the storage areas might be overwritten by a subsequent  call  to
       getnetbyaddr(), getnetbyname(), or getnetent().  The returned pointer, and pointers within the structure,
       might also be invalidated if the calling thread is terminated.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       The Base Definitions volume of POSIX.1‐2017, <netdb.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical  and  Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE  and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                     ENDNETENT(3POSIX)