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)  2007-2022, University of Amsterdam
    7                              VU University Amsterdam
    8    All rights reserved.
    9
   10    Redistribution and use in source and binary forms, with or without
   11    modification, are permitted provided that the following conditions
   12    are met:
   13
   14    1. Redistributions of source code must retain the above copyright
   15       notice, this list of conditions and the following disclaimer.
   16
   17    2. Redistributions in binary form must reproduce the above copyright
   18       notice, this list of conditions and the following disclaimer in
   19       the documentation and/or other materials provided with the
   20       distribution.
   21
   22    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   23    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   24    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   25    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   26    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   27    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   28    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   29    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   30    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   32    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   33    POSSIBILITY OF SUCH DAMAGE.
   34*/
   35
   36:- module(http_ssl_plugin, []).   37% Requires ssl:upgrade_legacy_options/2 hook
   38:- use_module(library(ssl),
   39              [ ssl_context/3,
   40                ssl_secure_ciphers/1,
   41                ssl_property/2,
   42                ssl_set_options/3,
   43                ssl_negotiate/5
   44              ]).   45:- use_module(library(debug),[debug/3]).   46:- use_module(library(socket),
   47              [ tcp_socket/1,
   48                tcp_setopt/2,
   49                tcp_bind/2,
   50                tcp_listen/2,
   51                tcp_accept/3,
   52                tcp_open_socket/3,
   53                tcp_connect/3
   54              ]).   55
   56:- autoload(library(lists),[select/3]).   57:- autoload(library(option),[option/2,option/3]).   58:- autoload(library(apply), [include/3]).   59:- autoload(library(http/http_header),[http_read_reply_header/2]).   60:- autoload(library(http/thread_httpd),[http_enough_workers/3]).

   73:- multifile
   74    thread_httpd:make_socket_hook/3,
   75    thread_httpd:accept_hook/2,
   76    thread_httpd:open_client_hook/6,
   77    thread_httpd:discard_client_hook/1,
   78    http:http_protocol_hook/5,
   79    http:open_options/2,
   80    http:http_connection_over_proxy/6,
   81    http:ssl_server_create_hook/3,
   82    http:ssl_server_open_client_hook/3.   83
   84
   85                 /*******************************
   86                 *          SERVER HOOKS        *
   87                 *******************************/

 thread_httpd:make_socket_hook(?Port, :OptionsIn, -OptionsOut) is semidet

Hook into http_server/2 to create an SSL server if the option ssl(SSLOptions) is provided.

See also

- thread_httpd:accept_hook/2 handles the corresponding accept

   97thread_httpd:make_socket_hook(Port, M:Options0, Options) :-
   98    select(ssl(SSLOptions0), Options0, Options1),
   99    !,
  100    add_secure_ciphers(SSLOptions0, SSLOptions1),
  101    disable_sslv3(SSLOptions1, SSLOptions),
  102    make_socket(Port, Socket, Options1),
  103    ssl_context(server, SSL0, M:[close_parent(true)|SSLOptions]),
  104    (   http:ssl_server_create_hook(SSL0, SSL1, Options1)
  105    ->  ensure_close_parent(SSL1, SSL)
  106    ;   SSL = SSL0
  107    ),
  108    atom_concat('httpsd', Port, Queue),
  109    Options = [ queue(Queue),
  110                tcp_socket(Socket),
  111                ssl_instance(SSL)
  112              | Options1
  113              ].
  114
  115ensure_close_parent(SSL0, SSL) :-
  116    (   ssl_property(SSL0, close_parent(true))
  117    ->  SSL = SSL0
  118    ;   ssl_set_options(SSL0, SSL, [close_parent(true)])
  119    ).

 add_secure_ciphers(+SSLOptions0, -SSLOptions)

Add ciphers from ssl_secure_ciphers/1 if no ciphers are provided.

  125add_secure_ciphers(SSLOptions0, SSLOptions) :-
  126    (   option(cipher_list(_), SSLOptions0)
  127    ->  SSLOptions = SSLOptions0
  128    ;   ssl_secure_ciphers(Ciphers),
  129        SSLOptions = [cipher_list(Ciphers)|SSLOptions0]
  130    ).

 disable_sslv3(+SSLOptions0, -SSLOptions)

Disable SSLv3, which is considered insecure unless the caller specifies the allowed versions explicitly, so we assume s/he knows what s/he is doing.

  138disable_sslv3(SSLOptions0, SSLOptions) :-
  139    (   option(min_protocol_version(_), SSLOptions0)
  140    ;   option(disable_ssl_methods(_), SSLOptions0)
  141    ),
  142    !,
  143    SSLOptions = SSLOptions0.
  144disable_sslv3(SSLOptions0,
  145              [ disable_ssl_methods([sslv3,sslv23]), % old OpenSSL versions
  146                min_protocol_version(tlsv1)          % OpenSSL 1.1.0 and later
  147              | SSLOptions0
  148              ]).
  149
  150
  151make_socket(_Port, Socket, Options) :-
  152    option(tcp_socket(Socket), Options),
  153    !.
  154make_socket(Port, Socket, _Options) :-
  155    tcp_socket(Socket),
  156    tcp_setopt(Socket, reuseaddr),
  157    tcp_bind(Socket, Port),
  158    tcp_listen(Socket, 5).

 thread_httpd:accept_hook(:Goal, +Options) is semidet

Implement the accept for HTTPS connections.

  165thread_httpd:accept_hook(Goal, Options) :-
  166    memberchk(ssl_instance(SSL0), Options),
  167    !,
  168    ensure_close_parent(SSL0, SSL),
  169    memberchk(queue(Queue), Options),
  170    memberchk(tcp_socket(Socket), Options),
  171    tcp_accept(Socket, Client, Peer),
  172    sig_atomic(send_to_worker(Queue, SSL, Client, Goal, Peer)),
  173    http_enough_workers(Queue, accept, Peer).
  174
  175send_to_worker(Queue, SSL, Client, Goal, Peer) :-
  176    debug(http(connection), 'New HTTPS connection from ~p', [Peer]),
  177    thread_send_message(Queue, ssl_client(SSL, Client, Goal, Peer)).

 thread_httpd:discard_client_hook(+Msg)

Handles connections that where accepted during server shutdown.

  183thread_httpd:discard_client_hook(ssl_client(_SSL, Client, _Goal, _Peer)) :-
  184    tcp_close_socket(Client).

 http:ssl_server_create_hook(+SSL0, -SSL, +Options) is semidet

Extensible predicate that is called once after creating an HTTPS server. If this predicate succeeds, SSL is the context that is used for negotiating new connections. Otherwise, SSL0 is used, which is the context that was created with the given options.

See also

- ssl_context/3 for creating an SSL context

 http:ssl_server_open_client_hook(+SSL0, -SSL, +Options) is semidet

Extensible predicate that is called before each connection that the server negotiates with a client. If this predicate succeeds, SSL is the context that is used for the new connection. Otherwise, SSL0 is used, which is the context that was created when launching the server.

See also

- ssl_context/3 for creating an SSL context

  208thread_httpd:open_client_hook(ssl_client(SSL0, Client, Goal, Peer),
  209                              Goal, In, Out,
  210                              [peer(Peer), protocol(https)],
  211                              Options) :-
  212    (   http:ssl_server_open_client_hook(SSL0, SSL, Options)
  213    ->  true
  214    ;   SSL = SSL0
  215    ),
  216    option(timeout(TMO), Options, 60),
  217    tcp_open_socket(Client, Read, Write),
  218    set_stream(Read, timeout(TMO)),
  219    set_stream(Write, timeout(TMO)),
  220    catch(ssl_negotiate(SSL, Read, Write, In, Out),
  221          E,
  222          ssl_failed(Read, Write, E)).
  223
  224ssl_failed(Read, Write, E) :-
  225    close(Write, [force(true)]),
  226    close(Read,  [force(true)]),
  227    throw(E).
  228
  229
  230                 /*******************************
  231                 *         CLIENT HOOKS         *
  232                 *******************************/

 http:http_protocol_hook(+Scheme, +Parts, +PlainStreamPair, -StreamPair, +Options) is semidet

Hook for http_open/3 to connect to an HTTPS (SSL-based HTTP) server.

  240http:http_protocol_hook(https, Parts, PlainStreamPair, StreamPair, Options) :-
  241    ssl_protocol_hook(Parts, PlainStreamPair, StreamPair, Options).
  242http:http_protocol_hook(wss, Parts, PlainStreamPair, StreamPair, Options) :-
  243    ssl_protocol_hook(Parts, PlainStreamPair, StreamPair, Options).
  244
  245ssl_protocol_hook(Parts, PlainStreamPair, StreamPair, Options) :-
  246    memberchk(host(Host), Parts),
  247    include(ssl_option, Options, SSLOptions),
  248    ssl_context(client, SSL, [ host(Host),
  249                               close_parent(true)
  250                             | SSLOptions
  251                             ]),
  252    stream_pair(PlainStreamPair, PlainIn, PlainOut),
  253    % if an exception arises, http_open/3 closes the stream for us
  254    ssl_negotiate(SSL, PlainIn, PlainOut, In, Out),
  255    stream_pair(StreamPair, In, Out).
  256
  257% Might be better to be more  selective,   but  passing the options from
  258% http_open/3 with more than 1 argument makes ssl_context/3 fail.
  259
  260ssl_option(Term) :-
  261    compound(Term),
  262    compound_name_arity(Term, _, 1).

 http:http_connection_over_proxy(+Proxy, +Parts, +HostPort, -StreamPair, +OptionsIn, -OptionsOut)

Facilitate an HTTPS connection via a proxy using HTTP CONNECT. Note that most proxies will only support this for connecting on port 443

  271http:http_connection_over_proxy(proxy(ProxyHost, ProxyPort), Parts,
  272                                Host:Port, StreamPair, Options, Options) :-
  273    memberchk(scheme(https), Parts),
  274    !,
  275    tcp_connect(ProxyHost:ProxyPort, StreamPair, [bypass_proxy(true)]),
  276    catch(negotiate_http_connect(StreamPair, Host:Port),
  277          Error,
  278          ( close(StreamPair, [force(true)]),
  279            throw(Error)
  280          )).
  281
  282negotiate_http_connect(StreamPair, Address):-
  283    format(StreamPair, 'CONNECT ~w HTTP/1.1\r\n\r\n', [Address]),
  284    flush_output(StreamPair),
  285    http_read_reply_header(StreamPair, Header),
  286    memberchk(status(_, Status, Message), Header),
  287    (   Status == ok
  288    ->  true
  289    ;   throw(error(proxy_rejection(Message), _))
  290    )