1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2008-2012, University of Amsterdam
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   32    POSSIBILITY OF SUCH DAMAGE.
   33*/
   34
   35:- module(doc_access,
   36          [ host_access_options/2       % +AllOptions, -NoAccessOptions
   37          ]).   38:- use_module(library(http/http_hook)).   39:- use_module(library(dcg/basics)).   40
   41:- dynamic
   42    can_edit/1,
   43    allow_from/1,
   44    deny_from/1.   45
   46:- meta_predicate
   47    match_peer(1, +, +).   48
   49%       http:authenticate(+Type, +Request, -Extra) is semidet.
   50%
   51%       PlDoc specific access control. The access   control  is based on
   52%       these options that are passed from starting PlDoc. If PlDoc runs
   53%       on  top  of   an   external    dispatch   loop,   the  predicate
   54%       host_access_options/2 can be used to specify access rights.
   55%
   56%           * allow(+IP)
   57%           * deny(+IP)
   58%           * edit(+Bool)
   59
   60http:authenticate(pldoc(read), Request, []) :-
   61    !,
   62    memberchk(peer(Peer), Request),
   63    allowed_peer(Peer).
   64http:authenticate(pldoc(edit), Request, []) :-
   65    !,
   66    (   can_edit(false)
   67    ->  fail
   68    ;   (   memberchk(x_forwarded_for(Forwarded), Request),
   69            primary_forwarded_host(Forwarded, IPAtom),
   70            parse_ip(IPAtom, Peer)
   71        ->  true
   72        ;   memberchk(peer(Peer), Request)
   73        ),
   74        match_peer(localhost, +, Peer)
   75    ).

 host_access_options(+AllOptions, -NoAuthOptions) is det

Filter the authorization options from AllOptions, leaving the remaining options in NoAuthOptions.

   83host_access_options([], []).
   84host_access_options([H|T0], T) :-
   85    host_access_option(H),
   86    !,
   87    host_access_options(T0, T).
   88host_access_options([H|T0], [H|T]) :-
   89    host_access_options(T0, T).
   90
   91host_access_option(allow(From)) :-
   92    assert(allow_from(From)).
   93host_access_option(deny(From)) :-
   94    assert(deny_from(From)).
   95host_access_option(edit(Bool)) :-
   96    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 '.'.

Arguments:

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.

  110match_peer(Spec, _, Peer) :-
  111    call(Spec, Peer),
  112    !.
  113match_peer(Spec, PM, Peer) :-
  114    (   call(Spec, HOrDom), atom(HOrDom)
  115    ->  (   catch(tcp_host_to_address(Host, Peer), E, true),
  116            var(E)
  117        ->  call(Spec, HostOrDomain),
  118            atom(HostOrDomain),
  119            (   sub_atom(HostOrDomain, 0, _, _, '.')
  120            ->  sub_atom(Host, _, _, 0, HostOrDomain)
  121            ;   HostOrDomain == Host
  122            )
  123        ;   PM == (+)
  124        ->  !, fail
  125        ;   true
  126        )
  127    ).

 allowed_peer(+Peer) is semidet

True if Peer is allowed according to the rules.

  133allowed_peer(Peer) :-
  134    match_peer(deny_from, -, Peer),
  135    !,
  136    match_peer(allow_from, +, Peer).
  137allowed_peer(Peer) :-
  138    allow_from(_),
  139    !,
  140    match_peer(allow_from, +, Peer).
  141allowed_peer(_).
  142
  143
  144:- dynamic
  145    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.

  153primary_forwarded_host(Spec, Host) :-
  154    sub_atom(Spec, B, _, _, ','),
  155    !,
  156    sub_atom(Spec, 0, B, _, Host).
  157primary_forwarded_host(Host, Host).
  158
  159
  160localhost(ip(127,0,0,1)).
  161localhost(localhost).
  162
  163parse_ip(Atom, IP) :-
  164    atom_codes(Atom, Codes),
  165    phrase(ip(IP), Codes).

 ip(?IP)// is semidet

Parses A.B.C.D into ip(A,B,C,D)

  171ip(ip(A,B,C,D)) -->
  172    integer(A), ".", integer(B), ".", integer(C), ".", integer(D)