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.\" $NetBSD: libblacklist.3,v 1.8 2017/10/22 10:31:57 abhinav Exp $
.\"
.\" Copyright (c) 2015 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Christos Zoulas.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd January 22, 2015
.Dt LIBBLACKLIST 3
.Os
.Sh NAME
.Nm blacklist_open ,
.Nm blacklist_close ,
.Nm blacklist_r ,
.Nm blacklist ,
.Nm blacklist_sa ,
.Nm blacklist_sa_r
.Nd Blacklistd notification library
.Sh LIBRARY
.Lb libblacklist
.Sh SYNOPSIS
.In blacklist.h
.Ft struct blacklist *
.Fn blacklist_open "void"
.Ft void
.Fn blacklist_close "struct blacklist *cookie"
.Ft int
.Fn blacklist "int action" "int fd" "const char *msg"
.Ft int
.Fn blacklist_r "struct blacklist *cookie" "int action" "int fd" "const char *msg"
.Ft int
.Fn blacklist_sa "int action" "int fd" "const struct sockaddr *sa" "socklen_t salen" "const char *msg"
.Ft int
.Fn blacklist_sa_r "struct blacklist *cookie" "int action" "int fd" "const struct sockaddr *sa" "socklen_t salen" "const char *msg"
.Sh DESCRIPTION
These functions can be used by daemons to notify
.Xr blacklistd 8
about successful and failed remote connections so that blacklistd can
block or release port access to prevent Denial of Service attacks.
.Pp
The function
.Fn blacklist_open
creates the necessary state to communicate with
.Xr blacklistd 8
and returns a pointer to it, or
.Dv NULL
on failure.
.Pp
The
.Fn blacklist_close
function frees all memory and resources used.
.Pp
The
.Fn blacklist
function sends a message to
.Xr blacklistd 8 ,
with an
.Ar action
argument specifying
.Dv 1
for a failed connection or
.Dv 0
for a successful connection,
a file descriptor
.Ar fd
specifying the accepted file descriptor connected to the client,
and an optional message in the
.Ar msg
argument.
.Pp
The
.Fn blacklist_r
function is more efficient because it keeps the blacklist state around.
.Pp
The
.Fn blacklist_sa
and
.Fn blacklist_sa_r
functions can be used with unconnected sockets, where
.Xr getpeername 2
will not work, the server will pass the peer name in the message.
.Pp
All functions log errors to
.Xr syslogd 8 .
.Sh RETURN VALUES
The function
.Fn blacklist_open
returns a cookie on success and
.Dv NULL
on failure setting
.Dv errno
to an appropriate value.
.Pp
The functions
.Fn blacklist ,
.Fn blacklist_sa ,
and
.Fn blacklist_sa_r
return
.Dv 0
on success and
.Dv \-1
on failure setting
.Dv errno
to an appropriate value.
.Sh SEE ALSO
.Xr blacklistd.conf 5 ,
.Xr blacklistd 8
.Sh AUTHORS
.An Christos Zoulas