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/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2008-2012, University of Amsterdam
All rights reserved.
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 COPYRIGHT HOLDERS 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
COPYRIGHT OWNER 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.
*/
:- module(doc_access,
[ host_access_options/2 % +AllOptions, -NoAccessOptions
]).
:- use_module(library(http/http_hook)).
:- use_module(library(dcg/basics)).
:- dynamic
can_edit/1,
allow_from/1,
deny_from/1.
:- meta_predicate
match_peer(1, +, +).
% http:authenticate(+Type, +Request, -Extra) is semidet.
%
% PlDoc specific access control. The access control is based on
% these options that are passed from starting PlDoc. If PlDoc runs
% on top of an external dispatch loop, the predicate
% host_access_options/2 can be used to specify access rights.
%
% * allow(+IP)
% * deny(+IP)
% * edit(+Bool)
http:authenticate(pldoc(read), Request, []) :-
!,
memberchk(peer(Peer), Request),
allowed_peer(Peer).
http:authenticate(pldoc(edit), Request, []) :-
!,
( can_edit(false)
-> fail
; ( memberchk(x_forwarded_for(Forwarded), Request),
primary_forwarded_host(Forwarded, IPAtom),
parse_ip(IPAtom, Peer)
-> true
; memberchk(peer(Peer), Request)
),
match_peer(localhost, +, Peer)
).
%! host_access_options(+AllOptions, -NoAuthOptions) is det.
%
% Filter the authorization options from AllOptions, leaving the
% remaining options in NoAuthOptions.
host_access_options([], []).
host_access_options([H|T0], T) :-
host_access_option(H),
!,
host_access_options(T0, T).
host_access_options([H|T0], [H|T]) :-
host_access_options(T0, T).
host_access_option(allow(From)) :-
assert(allow_from(From)).
host_access_option(deny(From)) :-
assert(deny_from(From)).
host_access_option(edit(Bool)) :-
assert(can_edit(Bool)).
%! match_peer(:RuleSet, +PlusMin, +Peer) is semidet.
%
% True if Peer is covered by the ruleset RuleSet. Peer is a term
% ip(A,B,C,D). RuleSet is a predicate with one argument that is
% either a partial ip term, a hostname or a domainname.
% Domainnames start with a '.'.
%
% @param PlusMin Positive/negative test. If IP->Host fails, a
% positive test fails, while a negative succeeds.
% I.e. deny('.com') succeeds for unknown IP
% addresses.
match_peer(Spec, _, Peer) :-
call(Spec, Peer),
!.
match_peer(Spec, PM, Peer) :-
( call(Spec, HOrDom), atom(HOrDom)
-> ( catch(tcp_host_to_address(Host, Peer), E, true),
var(E)
-> call(Spec, HostOrDomain),
atom(HostOrDomain),
( sub_atom(HostOrDomain, 0, _, _, '.')
-> sub_atom(Host, _, _, 0, HostOrDomain)
; HostOrDomain == Host
)
; PM == (+)
-> !, fail
; true
)
).
%! allowed_peer(+Peer) is semidet.
%
% True if Peer is allowed according to the rules.
allowed_peer(Peer) :-
match_peer(deny_from, -, Peer),
!,
match_peer(allow_from, +, Peer).
allowed_peer(Peer) :-
allow_from(_),
!,
match_peer(allow_from, +, Peer).
allowed_peer(_).
:- dynamic
can_edit/1.
%! primary_forwarded_host(+Spec, -Host) is det.
%
% x_forwarded host contains multiple hosts seperated by ', ' if
% there are multiple proxy servers in between. The first one is
% the one the user's browser knows about.
primary_forwarded_host(Spec, Host) :-
sub_atom(Spec, B, _, _, ','),
!,
sub_atom(Spec, 0, B, _, Host).
primary_forwarded_host(Host, Host).
localhost(ip(127,0,0,1)).
localhost(localhost).
parse_ip(Atom, IP) :-
atom_codes(Atom, Codes),
phrase(ip(IP), Codes).
%! ip(?IP)// is semidet.
%
% Parses A.B.C.D into ip(A,B,C,D)
ip(ip(A,B,C,D)) -->
integer(A), ".", integer(B), ".", integer(C), ".", integer(D).
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