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    port(Port, PortNum),
  109    atom_concat('httpsd', PortNum, Queue),
  110    Options = [ queue(Queue),
  111                tcp_socket(Socket),
  112                ssl_instance(SSL)
  113              | Options1
  114              ].
  115
  116port(_Host:Port0, Port) => Port = Port0.
  117port(Port0, Port), integer(Port0) => Port = Port0.
  118
  119ensure_close_parent(SSL0, SSL) :-
  120    (   ssl_property(SSL0, close_parent(true))
  121    ->  SSL = SSL0
  122    ;   ssl_set_options(SSL0, SSL, [close_parent(true)])
  123    ).

 add_secure_ciphers(+SSLOptions0, -SSLOptions)

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

  129add_secure_ciphers(SSLOptions0, SSLOptions) :-
  130    (   option(cipher_list(_), SSLOptions0)
  131    ->  SSLOptions = SSLOptions0
  132    ;   ssl_secure_ciphers(Ciphers),
  133        SSLOptions = [cipher_list(Ciphers)|SSLOptions0]
  134    ).

 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.

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

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

Implement the accept for HTTPS connections.

  169thread_httpd:accept_hook(Goal, Options) :-
  170    memberchk(ssl_instance(SSL0), Options),
  171    !,
  172    ensure_close_parent(SSL0, SSL),
  173    memberchk(queue(Queue), Options),
  174    memberchk(tcp_socket(Socket), Options),
  175    tcp_accept(Socket, Client, Peer),
  176    sig_atomic(send_to_worker(Queue, SSL, Client, Goal, Peer)),
  177    http_enough_workers(Queue, accept, Peer).
  178
  179send_to_worker(Queue, SSL, Client, Goal, Peer) :-
  180    debug(http(connection), 'New HTTPS connection from ~p', [Peer]),
  181    thread_send_message(Queue, ssl_client(SSL, Client, Goal, Peer)).

 thread_httpd:discard_client_hook(+Msg)

Handles connections that where accepted during server shutdown.

  187thread_httpd:discard_client_hook(ssl_client(_SSL, Client, _Goal, _Peer)) :-
  188    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

  212thread_httpd:open_client_hook(ssl_client(SSL0, Client, Goal, Peer),
  213                              Goal, In, Out,
  214                              [peer(Peer), protocol(https)],
  215                              Options) :-
  216    (   http:ssl_server_open_client_hook(SSL0, SSL, Options)
  217    ->  true
  218    ;   SSL = SSL0
  219    ),
  220    option(timeout(TMO), Options, 60),
  221    tcp_open_socket(Client, Read, Write),
  222    set_stream(Read, timeout(TMO)),
  223    set_stream(Write, timeout(TMO)),
  224    catch(ssl_negotiate(SSL, Read, Write, In, Out),
  225          E,
  226          ssl_failed(Read, Write, E)).
  227
  228ssl_failed(Read, Write, E) :-
  229    close(Write, [force(true)]),
  230    close(Read,  [force(true)]),
  231    throw(E).
  232
  233
  234                 /*******************************
  235                 *         CLIENT HOOKS         *
  236                 *******************************/

 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.

  244http:http_protocol_hook(https, Parts, PlainStreamPair, StreamPair, Options) :-
  245    ssl_protocol_hook(Parts, PlainStreamPair, StreamPair, Options).
  246http:http_protocol_hook(wss, Parts, PlainStreamPair, StreamPair, Options) :-
  247    ssl_protocol_hook(Parts, PlainStreamPair, StreamPair, Options).
  248
  249ssl_protocol_hook(Parts, PlainStreamPair, StreamPair, Options) :-
  250    memberchk(host(Host), Parts),
  251    include(ssl_option, Options, SSLOptions),
  252    ssl_context(client, SSL, [ host(Host),
  253                               close_parent(true)
  254                             | SSLOptions
  255                             ]),
  256    stream_pair(PlainStreamPair, PlainIn, PlainOut),
  257    % if an exception arises, http_open/3 closes the stream for us
  258    ssl_negotiate(SSL, PlainIn, PlainOut, In, Out),
  259    stream_pair(StreamPair, In, Out).
  260
  261% Might be better to be more  selective,   but  passing the options from
  262% http_open/3 with more than 1 argument makes ssl_context/3 fail.
  263
  264ssl_option(Term) :-
  265    compound(Term),
  266    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

  275http:http_connection_over_proxy(proxy(ProxyHost, ProxyPort), Parts,
  276                                Host:Port, StreamPair, Options, Options) :-
  277    memberchk(scheme(https), Parts),
  278    !,
  279    tcp_connect(ProxyHost:ProxyPort, StreamPair, [bypass_proxy(true)]),
  280    catch(negotiate_http_connect(StreamPair, Host:Port),
  281          Error,
  282          ( close(StreamPair, [force(true)]),
  283            throw(Error)
  284          )).
  285
  286negotiate_http_connect(StreamPair, Address):-
  287    format(StreamPair, 'CONNECT ~w HTTP/1.1\r\n\r\n', [Address]),
  288    flush_output(StreamPair),
  289    http_read_reply_header(StreamPair, Header),
  290    memberchk(status(_, Status, Message), Header),
  291    (   Status == ok
  292    ->  true
  293    ;   throw(error(proxy_rejection(Message), _))
  294    )