/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 2007-2022, University of Amsterdam VU University 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(http_ssl_plugin, []). % Requires ssl:upgrade_legacy_options/2 hook :- use_module(library(ssl), [ ssl_context/3, ssl_secure_ciphers/1, ssl_property/2, ssl_set_options/3, ssl_negotiate/5 ]). :- use_module(library(debug),[debug/3]). :- use_module(library(socket), [ tcp_socket/1, tcp_setopt/2, tcp_bind/2, tcp_listen/2, tcp_accept/3, tcp_open_socket/3, tcp_connect/3 ]). :- autoload(library(lists),[select/3]). :- autoload(library(option),[option/2,option/3]). :- autoload(library(apply), [include/3]). :- autoload(library(http/http_header),[http_read_reply_header/2]). :- autoload(library(http/thread_httpd),[http_enough_workers/3]). /** SSL plugin for HTTP libraries This module can be loaded next to library(thread_httpd) and library(http_open) to provide secure HTTP (HTTPS) services and client access. An example secure server using self-signed certificates can be found in the /doc/packages/examples/ssl/https.pl, where is the SWI-Prolog installation directory. */ :- multifile thread_httpd:make_socket_hook/3, thread_httpd:accept_hook/2, thread_httpd:open_client_hook/6, thread_httpd:discard_client_hook/1, http:http_protocol_hook/5, http:open_options/2, http:http_connection_over_proxy/6, http:ssl_server_create_hook/3, http:ssl_server_open_client_hook/3. /******************************* * SERVER HOOKS * *******************************/ %! 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 thread_httpd:accept_hook/2 handles the corresponding accept thread_httpd:make_socket_hook(Port, M:Options0, Options) :- select(ssl(SSLOptions0), Options0, Options1), !, add_secure_ciphers(SSLOptions0, SSLOptions1), disable_sslv3(SSLOptions1, SSLOptions), make_socket(Port, Socket, Options1), ssl_context(server, SSL0, M:[close_parent(true)|SSLOptions]), ( http:ssl_server_create_hook(SSL0, SSL1, Options1) -> ensure_close_parent(SSL1, SSL) ; SSL = SSL0 ), port(Port, PortNum), atom_concat('httpsd', PortNum, Queue), Options = [ queue(Queue), tcp_socket(Socket), ssl_instance(SSL) | Options1 ]. port(_Host:Port0, Port) => Port = Port0. port(Port0, Port), integer(Port0) => Port = Port0. ensure_close_parent(SSL0, SSL) :- ( ssl_property(SSL0, close_parent(true)) -> SSL = SSL0 ; ssl_set_options(SSL0, SSL, [close_parent(true)]) ). %! add_secure_ciphers(+SSLOptions0, -SSLOptions) % % Add ciphers from ssl_secure_ciphers/1 if no ciphers are provided. add_secure_ciphers(SSLOptions0, SSLOptions) :- ( option(cipher_list(_), SSLOptions0) -> SSLOptions = SSLOptions0 ; ssl_secure_ciphers(Ciphers), SSLOptions = [cipher_list(Ciphers)|SSLOptions0] ). %! 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. disable_sslv3(SSLOptions0, SSLOptions) :- ( option(min_protocol_version(_), SSLOptions0) ; option(disable_ssl_methods(_), SSLOptions0) ), !, SSLOptions = SSLOptions0. disable_sslv3(SSLOptions0, [ disable_ssl_methods([sslv3,sslv23]), % old OpenSSL versions min_protocol_version(tlsv1) % OpenSSL 1.1.0 and later | SSLOptions0 ]). make_socket(_Port, Socket, Options) :- option(tcp_socket(Socket), Options), !. make_socket(Port, Socket, _Options) :- tcp_socket(Socket), tcp_setopt(Socket, reuseaddr), tcp_bind(Socket, Port), tcp_listen(Socket, 5). %! thread_httpd:accept_hook(:Goal, +Options) is semidet. % % Implement the accept for HTTPS connections. thread_httpd:accept_hook(Goal, Options) :- memberchk(ssl_instance(SSL0), Options), !, ensure_close_parent(SSL0, SSL), memberchk(queue(Queue), Options), memberchk(tcp_socket(Socket), Options), tcp_accept(Socket, Client, Peer), sig_atomic(send_to_worker(Queue, SSL, Client, Goal, Peer)), http_enough_workers(Queue, accept, Peer). send_to_worker(Queue, SSL, Client, Goal, Peer) :- debug(http(connection), 'New HTTPS connection from ~p', [Peer]), thread_send_message(Queue, ssl_client(SSL, Client, Goal, Peer)). %! thread_httpd:discard_client_hook(+Msg) % % Handles connections that where accepted during server shutdown. thread_httpd:discard_client_hook(ssl_client(_SSL, Client, _Goal, _Peer)) :- 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 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 ssl_context/3 for creating an SSL context thread_httpd:open_client_hook(ssl_client(SSL0, Client, Goal, Peer), Goal, In, Out, [peer(Peer), protocol(https)], Options) :- ( http:ssl_server_open_client_hook(SSL0, SSL, Options) -> true ; SSL = SSL0 ), option(timeout(TMO), Options, 60), tcp_open_socket(Client, Read, Write), set_stream(Read, timeout(TMO)), set_stream(Write, timeout(TMO)), catch(ssl_negotiate(SSL, Read, Write, In, Out), E, ssl_failed(Read, Write, E)). ssl_failed(Read, Write, E) :- close(Write, [force(true)]), close(Read, [force(true)]), throw(E). /******************************* * CLIENT HOOKS * *******************************/ %! 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. http:http_protocol_hook(https, Parts, PlainStreamPair, StreamPair, Options) :- ssl_protocol_hook(Parts, PlainStreamPair, StreamPair, Options). http:http_protocol_hook(wss, Parts, PlainStreamPair, StreamPair, Options) :- ssl_protocol_hook(Parts, PlainStreamPair, StreamPair, Options). ssl_protocol_hook(Parts, PlainStreamPair, StreamPair, Options) :- memberchk(host(Host), Parts), include(ssl_option, Options, SSLOptions), ssl_context(client, SSL, [ host(Host), close_parent(true) | SSLOptions ]), stream_pair(PlainStreamPair, PlainIn, PlainOut), % if an exception arises, http_open/3 closes the stream for us ssl_negotiate(SSL, PlainIn, PlainOut, In, Out), stream_pair(StreamPair, In, Out). % Might be better to be more selective, but passing the options from % http_open/3 with more than 1 argument makes ssl_context/3 fail. ssl_option(Term) :- compound(Term), 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 http:http_connection_over_proxy(proxy(ProxyHost, ProxyPort), Parts, Host:Port, StreamPair, Options, Options) :- memberchk(scheme(https), Parts), !, tcp_connect(ProxyHost:ProxyPort, StreamPair, [bypass_proxy(true)]), catch(negotiate_http_connect(StreamPair, Host:Port), Error, ( close(StreamPair, [force(true)]), throw(Error) )). negotiate_http_connect(StreamPair, Address):- format(StreamPair, 'CONNECT ~w HTTP/1.1\r\n\r\n', [Address]), flush_output(StreamPair), http_read_reply_header(StreamPair, Header), memberchk(status(_, Status, Message), Header), ( Status == ok -> true ; throw(error(proxy_rejection(Message), _)) ).