ENDNETENT(3)               POSIX Programmer's Manual              ENDNETENT(3)



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

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(3)
