xref: /minix3/external/bsd/blacklist/lib/libblacklist.3 (revision 0a6a1f1d05b60e214de2f05a7310ddd1f0e590e7)

.\" $NetBSD: libblacklist.3,v 1.3 2015/01/25 23:09:28 wiz Exp $
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.\" Copyright (c) 2015 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Christos Zoulas.
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.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 a 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 bl_open
returns a cookie on success and
.Dv NULL
on failure setting errno to an appropriate value.
.Pp
The
.Fn bl_send
function returns
.Dv 0
on success and
.Dv -1
on failure setting errno to an appropriate value.
.Sh SEE ALSO
.Xr blacklistd.conf 5 ,
.Xr blacklistd 8
.Sh AUTHORS
.An Christos Zoulas