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/* Part of SWI-Prolog
Author: Jan Wielemaker & Steve Prior
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2004-2022, University of Amsterdam
VU University Amsterdam
CWI, Amsterdam
SWI-Prolog Solutions b.v.
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(prolog_server,
[ prolog_server/2 % +Port, +Options
]).
:- autoload(library(lists),[member/2]).
:- autoload(library(socket),
[ tcp_socket/1,
tcp_setopt/2,
tcp_bind/2,
tcp_listen/2,
tcp_accept/3,
tcp_open_socket/3,
tcp_host_to_address/2
]).
%! prolog_server(?Port, +Options)
%
% Create a TCP/IP based server on the given Port, so you can
% telnet into Prolog and run an interactive session. This library
% is intended to provide access for debugging and management of
% embedded servers.
%
% Currently defined options are:
%
% * allow(IP)
% Allow access from IP, a term of the format ip(A,B,C,D).
% Multiple of such terms can exist and access is granted
% if the peer IP address unifies to one of them. If no
% allow option is provided access is only granted from
% ip(127,0,0,1) (localhost).
%
% For example:
%
% ==
% ?- prolog_server(4000, []).
%
% % netcat -N localhost 4000
% Welcome to the SWI-Prolog server on thread 3
%
% 1 ?-
% ==
%
% @bug As the connection does not involve a terminal, command
% history and completion are not provided. Neither are interrupts
% (Control-C). The Prolog shell can be terminated if `netcat` shuts
% down the socket on ^D (using the `-N` option). Otherwise one must
% enter the command "end_of_file."
% @see The add-on `libssh` provides an embedded SSH server. This
% provides encryption as well as a _pseudo terminal_ for a better
% user experience.
prolog_server(Port, Options) :-
tcp_socket(ServerSocket),
tcp_setopt(ServerSocket, reuseaddr),
tcp_bind(ServerSocket, Port),
tcp_listen(ServerSocket, 5),
thread_create(server_loop(ServerSocket, Options), _,
[ alias(prolog_server)
]).
server_loop(ServerSocket, Options) :-
tcp_accept(ServerSocket, Slave, Peer),
tcp_open_socket(Slave, InStream, OutStream),
set_stream(InStream, close_on_abort(false)),
set_stream(OutStream, close_on_abort(false)),
tcp_host_to_address(Host, Peer),
( Postfix = []
; between(2, 1000, Num),
Postfix = [-, Num]
),
atomic_list_concat(['client@', Host | Postfix], Alias),
catch(thread_create(
service_client(InStream, OutStream, Peer, Options),
_,
[ alias(Alias),
detached(true)
]),
error(permission_error(create, thread, Alias), _),
fail),
!,
server_loop(ServerSocket, Options).
service_client(InStream, OutStream, Peer, Options) :-
allow(Peer, Options),
!,
thread_self(Id),
set_prolog_IO(InStream, OutStream, OutStream),
set_stream(InStream, tty(true)),
set_prolog_flag(tty_control, false),
current_prolog_flag(encoding, Enc),
set_stream(user_input, encoding(Enc)),
set_stream(user_output, encoding(Enc)),
set_stream(user_error, encoding(Enc)),
set_stream(user_input, newline(detect)),
set_stream(user_output, newline(dos)),
set_stream(user_error, newline(dos)),
format(user_error,
'Welcome to the SWI-Prolog server on thread ~w~n~n',
[Id]),
call_cleanup(prolog,
( close(InStream, [force(true)]),
close(OutStream, [force(true)]))).
service_client(InStream, OutStream, _, _):-
thread_self(Id),
format(OutStream, 'Go away!!~n', []),
close(InStream),
close(OutStream),
thread_detach(Id).
allow(Peer, Options) :-
( member(allow(Allow), Options)
*-> Peer = Allow,
!
; Peer = ip(127,0,0,1)
).
|
