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
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
These functions need not be reentrant. A function that is not required to be
reentrant is not required to be thread-safe.
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
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 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