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) 2000-2023, University of Amsterdam 7 VU University Amsterdam 8 CWI, Amsterdam 9 SWI-Prolog Solutions b.v. 10 All rights reserved. 11 12 Redistribution and use in source and binary forms, with or without 13 modification, are permitted provided that the following conditions 14 are met: 15 16 1. Redistributions of source code must retain the above copyright 17 notice, this list of conditions and the following disclaimer. 18 19 2. Redistributions in binary form must reproduce the above copyright 20 notice, this list of conditions and the following disclaimer in 21 the documentation and/or other materials provided with the 22 distribution. 23 24 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 25 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 26 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 27 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 28 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 29 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 30 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 31 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 32 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 34 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35 POSSIBILITY OF SUCH DAMAGE. 36*/ 37 38:- module(socket, 39 [ socket_create/2, % -Socket, +Options 40 tcp_socket/1, % -Socket 41 tcp_close_socket/1, % +Socket 42 tcp_open_socket/3, % +Socket, -Read, -Write 43 tcp_connect/2, % +Socket, +Address 44 tcp_connect/3, % +Address, -StreamPair, +Options 45 tcp_connect/4, % +Socket, +Address, -Read, -Write) 46 tcp_bind/2, % +Socket, +Address 47 tcp_accept/3, % +Master, -Slave, -PeerName 48 tcp_listen/2, % +Socket, +BackLog 49 tcp_fcntl/3, % +Socket, +Command, ?Arg 50 tcp_setopt/2, % +Socket, +Option 51 tcp_getopt/2, % +Socket, ?Option 52 host_address/3, % ?HostName, ?Address, +Options 53 tcp_host_to_address/2, % ?HostName, ?Ip-nr 54 tcp_select/3, % +Inputs, -Ready, +Timeout 55 gethostname/1, % -HostName 56 57 ip_name/2, % ?Ip, ?Name 58 59 tcp_open_socket/2, % +Socket, -StreamPair 60 61 udp_socket/1, % -Socket 62 udp_receive/4, % +Socket, -Data, -Sender, +Options 63 udp_send/4, % +Socket, +Data, +Sender, +Options 64 65 negotiate_socks_connection/2% +DesiredEndpoint, +StreamPair 66 ]). 67:- autoload(library(debug), [assertion/1, debug/3]). 68:- autoload(library(lists), [last/2, member/2, append/3, append/2]). 69:- autoload(library(apply), [maplist/3, maplist/2]). 70:- autoload(library(error), 71 [instantiation_error/1, syntax_error/1, must_be/2, domain_error/2]). 72:- autoload(library(option), [option/2, option/3]). 73 74/** <module> Network socket (TCP and UDP) library 75 76The library(socket) provides TCP and UDP inet-domain sockets from 77SWI-Prolog, both client and server-side communication. The interface of 78this library is very close to the Unix socket interface, also supported 79by the MS-Windows _winsock_ API. SWI-Prolog applications that wish to 80communicate with multiple sources have two options: 81 82 - Use I/O multiplexing based on wait_for_input/3. On Windows 83 systems this can only be used for sockets, not for general 84 (device-) file handles. 85 - Use multiple threads, handling either a single blocking socket 86 or a pool using I/O multiplexing as above. 87 88## Client applications {#socket-server} 89 90Using this library to establish a TCP connection to a server is as 91simple as opening a file. See also http_open/3. 92 93== 94dump_swi_homepage :- 95 setup_call_cleanup( 96 tcp_connect('www.swi-prolog.org':http, Stream, []), 97 ( format(Stream, 98 'GET / HTTP/1.1~n\c 99 Host: www.swi-prolog.org~n\c 100 Connection: close~n~n', []), 101 flush_output(Stream), 102 copy_stream_data(Stream, current_output) 103 ), 104 close(Stream)). 105== 106 107To deal with timeouts and multiple connections, threads, 108wait_for_input/3 and/or non-blocking streams (see tcp_fcntl/3) can be 109used. 110 111## Server applications {#socket-client} 112 113The typical sequence for generating a server application is given below. 114To close the server, use close/1 on `AcceptFd`. 115 116 == 117 create_server(Port) :- 118 tcp_socket(Socket), 119 tcp_bind(Socket, Port), 120 tcp_listen(Socket, 5), 121 tcp_open_socket(Socket, AcceptFd, _), 122 <dispatch> 123 == 124 125There are various options for <dispatch>. The most commonly used option 126is to start a Prolog thread to handle the connection. Alternatively, 127input from multiple clients can be handled in a single thread by 128listening to these clients using wait_for_input/3. Finally, on Unix 129systems, we can use fork/1 to handle the connection in a new process. 130Note that fork/1 and threads do not cooperate well. Combinations can be 131realised but require good understanding of POSIX thread and 132fork-semantics. 133 134Below is the typical example using a thread. Note the use of 135setup_call_cleanup/3 to guarantee that all resources are reclaimed, also 136in case of failure or exceptions. 137 138 == 139 dispatch(AcceptFd) :- 140 tcp_accept(AcceptFd, Socket, Peer), 141 thread_create(process_client(Socket, Peer), _, 142 [ detached(true) 143 ]), 144 dispatch(AcceptFd). 145 146 process_client(Socket, Peer) :- 147 setup_call_cleanup( 148 tcp_open_socket(Socket, StreamPair), 149 handle_service(StreamPair), 150 close(StreamPair)). 151 152 handle_service(StreamPair) :- 153 ... 154 == 155 156## Socket exceptions {#socket-exceptions} 157 158Errors that are trapped by the low-level library are mapped to an 159exception of the shape below. In this term, `Code` is a lower case atom 160that corresponds to the C macro name, e.g., `epipe` for a broken pipe. 161`Message` is the human readable string for the error code returned by 162the OS or the same as `Code` if the OS does not provide this 163functionality. Note that `Code` is derived from a static set of macros 164that may or may not be defines for the target OS. If the macro name is 165not known, `Code` is =|ERROR_nnn|=, where _nnn_ is an integer. 166 167 error(socket_error(Code, Message), _) 168 169Note that on Windows `Code` is a ``wsa*`` code which makes it hard to 170write portable code that handles specific socket errors. Even on POSIX 171systems the exact set of errors produced by the network stack is not 172defined. 173 174## Socket addresses (families) {#socket-domains} 175 176The library supports both IP4 and IP6 addresses. On Unix systems it also 177supports _Unix domain sockets_ (``AF_UNIX``). The address of a Unix 178domain sockets is a file name. Unix domain sockets are created using 179socket_create/2 or unix_domain_socket/1. 180 181IP4 or IP6 sockets can be created using socket_create/2 or tcp_connect/3 182with the `inet` (default, IP3) or `inet6` domain option. Some of the 183predicates produce or consume IP addresses as a Prolog term. The format 184of this term is one of: 185 186 - ip(A,B,C,D) 187 Represents an IP4 address. Each field is an integer in the range 188 0..255 (8 bit). 189 - ip(A,B,C,D,E,F,G,H) 190 Represents an IP6 address. Each field is an integer in the range 191 0..65535 (16 bit). 192 193The predicate ip_name/2 translates between the canonical textual 194representation and the above defined address terms. 195 196## Socket predicate reference {#socket-predicates} 197*/ 198 199:- multifile 200 tcp_connect_hook/3, % +Socket, +Addr, -In, -Out 201 tcp_connect_hook/4, % +Socket, +Addr, -Stream 202 proxy_for_url/3, % +URL, +Host, -ProxyList 203 try_proxy/4. % +Proxy, +Addr, -Socket, -Stream 204 205:- predicate_options(tcp_connect/3, 3, 206 [ bypass_proxy(boolean), 207 nodelay(boolean), 208 domain(oneof([inet,inet6])) 209 ]). 210 211:- use_foreign_library(foreign(socket)). 212:- public tcp_debug/1. % set debugging. 213 214:- if(current_predicate(unix_domain_socket/1)). 215:- export(unix_domain_socket/1). % -Socket 216:- endif. 217 218%! socket_create(-SocketId, +Options) is det. 219% 220% Create a socket according to Options. Supported Options are: 221% 222% - domain(+Domain) 223% One of `inet` (default), `inet6`, `unix` or `local` (same 224% as `unix`) 225% - type(+Type) 226% One of `stream` (default) to create a TCP connection or 227% `dgram` to create a UDP socket. 228% 229% This predicate subsumes tcp_socket/1m, udp_socket/1 and 230% unix_domain_socket/1. 231 232%! tcp_socket(-SocketId) is det. 233% 234% Equivalent to socket_create(SocketId, []) or, explicit, 235% socket_create(SocketId, [domain(inet), type(stream)]). 236 237%! unix_domain_socket(-SocketId) is det. 238% 239% Equivalent to socket_create(SocketId, [domain(unix)]) or, 240% explicit, socket_create(SocketId, [domain(unix), type(stream)]) 241% 242% Unix domain socket affect tcp_connect/2 (for clients) and 243% tcp_bind/2 and tcp_accept/3 (for servers). The address is an atom 244% or string that is handled as a file name. On most systems the 245% length of this file name is limited to 128 bytes (including null 246% terminator), but according to the Linux documentation (unix(7)), 247% portable applications must keep the address below 92 bytes. Note 248% that these lengths are in bytes. Non-ascii characters may be 249% represented as multiple bytes. If the length limit is exceeded a 250% representation_error(af_unix_name) exception is raised. 251 252%! tcp_close_socket(+SocketId) is det. 253% 254% Closes the indicated socket, making SocketId invalid. Normally, 255% sockets are closed by closing both stream handles returned by 256% open_socket/3. There are two cases where tcp_close_socket/1 is 257% used because there are no stream-handles: 258% 259% - If, after tcp_accept/3, the server uses fork/1 to handle the 260% client in a sub-process. In this case the accepted socket is 261% not longer needed from the main server and must be discarded 262% using tcp_close_socket/1. 263% - If, after discovering the connecting client with 264% tcp_accept/3, the server does not want to accept the 265% connection, it should discard the accepted socket 266% immediately using tcp_close_socket/1. 267 268%! tcp_open_socket(+SocketId, -StreamPair) is det. 269% 270% Create streams to communicate to SocketId. If SocketId is a 271% master socket (see tcp_bind/2), StreamPair should be used for 272% tcp_accept/3. If SocketId is a connected (see tcp_connect/2) or 273% accepted socket (see tcp_accept/3), StreamPair is unified to a 274% stream pair (see stream_pair/3) that can be used for reading and 275% writing. The stream or pair must be closed with close/1, which 276% also closes SocketId. 277 278tcp_open_socket(Socket, Stream) :- 279 tcp_open_socket(Socket, In, Out), 280 ( var(Out) 281 -> Stream = In 282 ; stream_pair(Stream, In, Out) 283 ). 284 285%! tcp_open_socket(+SocketId, -InStream, -OutStream) is det. 286% 287% Similar to tcp_open_socket/2, but creates two separate sockets 288% where tcp_open_socket/2 would have created a stream pair. 289% 290% @deprecated New code should use tcp_open_socket/2 because 291% closing a stream pair is much easier to perform safely. 292 293%! tcp_bind(SocketId, ?Address) is det. 294% 295% Bind the socket to Address on the current machine. This 296% operation, together with tcp_listen/2 and tcp_accept/3 implement 297% the _server-side_ of the socket interface. Address is either an 298% plain `Port` or a term HostPort. The first form binds the socket 299% to the given port on all interfaces, while the second only binds 300% to the matching interface. A typical example is below, causing 301% the socket to listen only on port 8080 on the local machine's 302% network. 303% 304% == 305% tcp_bind(Socket, localhost:8080) 306% == 307% 308% If `Port` is unbound, the system picks an arbitrary free port 309% and unifies `Port` with the selected port number. `Port` is 310% either an integer or the name of a registered service. See also 311% tcp_connect/4. 312 313%! tcp_listen(+SocketId, +BackLog) is det. 314% 315% Tells, after tcp_bind/2, the socket to listen for incoming 316% requests for connections. Backlog indicates how many pending 317% connection requests are allowed. Pending requests are requests 318% that are not yet acknowledged using tcp_accept/3. If the 319% indicated number is exceeded, the requesting client will be 320% signalled that the service is currently not available. A 321% commonly used default value for Backlog is 5. 322 323%! tcp_accept(+Socket, -Slave, -Peer) is det. 324% 325% This predicate waits on a server socket for a connection request by 326% a client. On success, it creates a new socket for the client and 327% binds the identifier to Slave. Peer is bound to the IP-address of 328% the client or the atom `af_unix` if Socket is an AF_UNIX socket (see 329% unix_domain_socket/1). 330 331%! tcp_connect(+SocketId, +Address) is det. 332% 333% Connect SocketId. After successful completion, tcp_open_socket/3 334% can be used to create I/O-Streams to the remote socket. This 335% predicate is part of the low level client API. A connection to a 336% particular host and port is realised using these steps: 337% 338% == 339% tcp_socket(Socket), 340% tcp_connect(Socket, Host:Port), 341% tcp_open_socket(Socket, StreamPair) 342% == 343% 344% Typical client applications should use the high level interface 345% provided by tcp_connect/3 which avoids resource leaking if a 346% step in the process fails, and can be hooked to support proxies. 347% For example: 348% 349% == 350% setup_call_cleanup( 351% tcp_connect(Host:Port, StreamPair, []), 352% talk(StreamPair), 353% close(StreamPair)) 354% == 355% 356% If SocketId is an AF_UNIX socket (see unix_domain_socket/1), Address 357% is an atom or string denoting a file name. 358 359 360 /******************************* 361 * HOOKABLE CONNECT * 362 *******************************/ 363 364%! tcp_connect(+Socket, +Address, -Read, -Write) is det. 365% 366% Connect a (client) socket to Address and return a bi-directional 367% connection through the stream-handles Read and Write. This 368% predicate may be hooked by defining socket:tcp_connect_hook/4 369% with the same signature. Hooking can be used to deal with proxy 370% connections. E.g., 371% 372% == 373% :- multifile socket:tcp_connect_hook/4. 374% 375% socket:tcp_connect_hook(Socket, Address, Read, Write) :- 376% proxy(ProxyAdress), 377% tcp_connect(Socket, ProxyAdress), 378% tcp_open_socket(Socket, Read, Write), 379% proxy_connect(Address, Read, Write). 380% == 381% 382% @deprecated New code should use tcp_connect/3 called as 383% tcp_connect(+Address, -StreamPair, +Options). 384 385tcp_connect(Socket, Address, Read, Write) :- 386 tcp_connect_hook(Socket, Address, Read, Write), 387 !. 388tcp_connect(Socket, Address, Read, Write) :- 389 tcp_connect(Socket, Address), 390 tcp_open_socket(Socket, Read, Write). 391 392 393 394%! tcp_connect(+Address, -StreamPair, +Options) is det. 395%! tcp_connect(+Socket, +Address, -StreamPair) is det. 396% 397% Establish a TCP communication as a client. The +,-,+ mode is the 398% preferred way for a client to establish a connection. This predicate 399% can be hooked to support network proxies. To use a proxy, the hook 400% proxy_for_url/3 must be defined. Permitted options are: 401% 402% * bypass_proxy(+Boolean) 403% Defaults to =false=. If =true=, do not attempt to use any 404% proxies to obtain the connection 405% 406% * nodelay(+Boolean) 407% Defaults to =false=. If =true=, set nodelay on the 408% resulting socket using tcp_setopt(Socket, nodelay) 409% 410% * domain(+Domain) 411% One of `inet' or `inet6`. When omitted we use host_address/2 412% with type(stream) and try the returned addresses in order. 413% 414% The +,+,- mode is deprecated and does not support proxies. It 415% behaves like tcp_connect/4, but creates a stream pair (see 416% stream_pair/3). 417% 418% @arg Address is either a Host:Port term or a file name (atom or 419% string). The latter connects to an AF_UNIX socket and requires 420% unix_domain_socket/1. 421% 422% @error proxy_error(tried(ResultList)) is raised by mode (+,-,+) if 423% proxies are defines by proxy_for_url/3 but no proxy can establsh the 424% connection. `ResultList` contains one or more terms of the form 425% false(Proxy) for a hook that simply failed or error(Proxy, 426% ErrorTerm) for a hook that raised an exception. 427% 428% @see library(http/http_proxy) defines a hook that allows to connect 429% through HTTP proxies that support the =CONNECT= method. 430 431% Main mode: +,-,+ 432tcp_connect(Address, StreamPair, Options) :- 433 var(StreamPair), 434 !, 435 ( memberchk(bypass_proxy(true), Options) 436 -> tcp_connect_direct(Address, Socket, StreamPair, Options) 437 ; findall(Result, 438 try_a_proxy(Address, Result), 439 ResultList), 440 last(ResultList, Status) 441 -> ( Status = true(_Proxy, Socket, StreamPair) 442 -> true 443 ; throw(error(proxy_error(tried(ResultList)), _)) 444 ) 445 ; tcp_connect_direct(Address, Socket, StreamPair, Options) 446 ), 447 ( memberchk(nodelay(true), Options) 448 -> tcp_setopt(Socket, nodelay) 449 ; true 450 ). 451% backward compatibility mode +,+,- 452tcp_connect(Socket, Address, StreamPair) :- 453 tcp_connect_hook(Socket, Address, StreamPair0), 454 !, 455 StreamPair = StreamPair0. 456tcp_connect(Socket, Address, StreamPair) :- 457 connect_stream_pair(Socket, Address, StreamPair). 458 459:- public tcp_connect_direct/3. % used by HTTP proxy code. 460tcp_connect_direct(Address, Socket, StreamPair) :- 461 tcp_connect_direct(Address, Socket, StreamPair, []). 462 463%! tcp_connect_direct(+Address, +Socket, -StreamPair, +Options) is det. 464% 465% Make a direct connection to a TCP address, i.e., do not take proxy 466% rules into account. If no explicit domain (`inet`, `inet6` is 467% given, perform a getaddrinfo() call to obtain the relevant 468% addresses. 469 470tcp_connect_direct(Host:Port, Socket, StreamPair, Options) :- 471 \+ option(domain(_), Options), 472 !, 473 State = error(_), 474 ( host_address(Host, Address, [type(stream)]), 475 socket_create(Socket, [domain(Address.domain)]), 476 E = error(_,_), 477 catch(connect_or_discard_socket(Socket, Address.address:Port, 478 StreamPair), 479 E, store_error_and_fail(State, E)), 480 debug(socket, '~p: connected to ~p', [Host, Address.address]) 481 -> true 482 ; arg(1, State, Error), 483 assertion(nonvar(Error)), 484 throw(Error) 485 ). 486tcp_connect_direct(Address, Socket, StreamPair, Options) :- 487 make_socket(Address, Socket, Options), 488 connect_or_discard_socket(Socket, Address, StreamPair). 489 490connect_or_discard_socket(Socket, Address, StreamPair) :- 491 setup_call_catcher_cleanup( 492 true, 493 connect_stream_pair(Socket, Address, StreamPair), 494 Catcher, cleanup(Catcher, Socket)). 495 496cleanup(exit, _) :- !. 497cleanup(_, Socket) :- 498 tcp_close_socket(Socket). 499 500connect_stream_pair(Socket, Address, StreamPair) :- 501 tcp_connect(Socket, Address, Read, Write), 502 stream_pair(StreamPair, Read, Write). 503 504store_error_and_fail(State, E) :- 505 arg(1, State, E0), 506 var(E0), 507 nb_setarg(1, State, E), 508 fail. 509 510:- if(current_predicate(unix_domain_socket/1)). 511make_socket(Address, Socket, _Options) :- 512 ( atom(Address) 513 ; string(Address) 514 ), 515 !, 516 unix_domain_socket(Socket). 517:- endif. 518make_socket(_Address, Socket, Options) :- 519 option(domain(Domain), Options, inet), 520 socket_create(Socket, [domain(Domain)]). 521 522 523%! tcp_select(+ListOfStreams, -ReadyList, +TimeOut) 524% 525% Same as the built-in wait_for_input/3. Used to allow for interrupts 526% and timeouts on Windows. A redesign of the Windows socket interface 527% makes it impossible to do better than Windows select() call 528% underlying wait_for_input/3. As input multiplexing typically happens 529% in a background thread anyway we accept the loss of timeouts and 530% interrupts. 531% 532% @deprecated Use wait_for_input/3 533 534tcp_select(ListOfStreams, ReadyList, TimeOut) :- 535 wait_for_input(ListOfStreams, ReadyList, TimeOut). 536 537 538 /******************************* 539 * PROXY SUPPORT * 540 *******************************/ 541 542try_a_proxy(Address, Result) :- 543 format(atom(URL), 'socket://~w', [Address]), 544 ( Address = Host:_ 545 -> true 546 ; Host = Address 547 ), 548 proxy_for_url(URL, Host, Proxy), 549 debug(socket(proxy), 'Socket connecting via ~w~n', [Proxy]), 550 ( catch(try_proxy(Proxy, Address, Socket, Stream), E, true) 551 -> ( var(E) 552 -> !, Result = true(Proxy, Socket, Stream) 553 ; Result = error(Proxy, E) 554 ) 555 ; Result = false(Proxy) 556 ), 557 debug(socket(proxy), 'Socket: ~w: ~p', [Proxy, Result]). 558 559%! try_proxy(+Proxy, +TargetAddress, -Socket, -StreamPair) is semidet. 560% 561% Attempt a socket-level connection via the given proxy to 562% TargetAddress. The Proxy argument must match the output argument 563% of proxy_for_url/3. The predicate tcp_connect/3 (and http_open/3 564% from the library(http/http_open)) collect the results of failed 565% proxies and raise an exception no proxy is capable of realizing 566% the connection. 567% 568% The default implementation recognises the values for Proxy 569% described below. The library(http/http_proxy) adds 570% proxy(Host,Port) which allows for HTTP proxies using the 571% =CONNECT= method. 572% 573% - direct 574% Do not use any proxy 575% - socks(Host, Port) 576% Use a SOCKS5 proxy 577 578:- multifile 579 try_proxy/4. 580 581try_proxy(direct, Address, Socket, StreamPair) :- 582 !, 583 tcp_connect_direct(Address, Socket, StreamPair). 584try_proxy(socks(Host, Port), Address, Socket, StreamPair) :- 585 !, 586 tcp_connect_direct(Host:Port, Socket, StreamPair), 587 catch(negotiate_socks_connection(Address, StreamPair), 588 Error, 589 ( close(StreamPair, [force(true)]), 590 throw(Error) 591 )). 592 593%! proxy_for_url(+URL, +Hostname, -Proxy) is nondet. 594% 595% This hook can be implemented to return a proxy to try when 596% connecting to URL. Returned proxies are tried in the order in 597% which they are returned by the multifile hook try_proxy/4. 598% Pre-defined proxy methods are: 599% 600% * direct 601% connect directly to the resource 602% * proxy(Host, Port) 603% Connect to the resource using an HTTP proxy. If the 604% resource is not an HTTP URL, then try to connect using the 605% CONNECT verb, otherwise, use the GET verb. 606% * socks(Host, Port) 607% Connect to the resource via a SOCKS5 proxy 608% 609% These correspond to the proxy methods defined by PAC [Proxy 610% auto-config](http://en.wikipedia.org/wiki/Proxy_auto-config). 611% Additional methods can be returned if suitable clauses for 612% http:http_connection_over_proxy/6 or try_proxy/4 are defined. 613 614:- multifile 615 proxy_for_url/3. 616 617%! udp_socket(-SocketId) is det. 618% 619% Equivalent to socket_create(SocketId, [type(dgram)]) or, explicit, 620% socket_create(SocketId, [domain(inet), type(dgram)]). 621 622%! udp_receive(+Socket, -Data, -From, +Options) is det. 623% 624% Wait for and return the next datagram. The Data is returned as a 625% Prolog term depending on Options. From is a term of the format 626% Ip:Port indicating the sender of the message. Here, `Ip` is either 627% an ip4 or ip6 structure. Socket can be waited for using 628% wait_for_input/3. Defined Options: 629% 630% - as(+Type) 631% Defines the type for Data. Possible values are `atom`, `codes`, 632% `string` (default) or `term` (parse as Prolog term). 633% - encoding(+Encoding) 634% Specify the encoding used to interpret the message. It is one of 635% `octet`. `iso_latin_1`, `text` or `utf8`. 636% - max_message_size(+Size) 637% Specify the maximum number of bytes to read from a UDP 638% datagram. Size must be within the range 0-65535. If unspecified, 639% a maximum of 4096 bytes will be read. 640% 641% For example: 642% 643% ``` 644% receive(Port) :- 645% udp_socket(Socket), 646% tcp_bind(Socket, Port), 647% repeat, 648% udp_receive(Socket, Data, From, [as(atom)]), 649% format('Got ~q from ~q~n', [Data, From]), 650% fail. 651% ``` 652 653 654%! udp_send(+Socket, +Data, +To, +Options) is det. 655% 656% Send a UDP message. Data is a string, atom or code-list providing 657% the data. To is an address of the form Host:Port where Host is 658% either the hostname or an IP address. Defined Options are: 659% 660% - encoding(+Encoding) 661% Specifies the encoding to use for the string. See 662% udp_receive/4 for details 663% - as(+Type) 664% This uses the same values for Type as the as(Type) option of 665% udp_receive/4. The are interpreted differently though. No Type 666% corresponds to CVT_ALL of PL_get_chars(). Using atom 667% corresponds to CVT_ATOM and any of string or codes is mapped 668% to CVT_STRING|CVT_LIST, allowing for a SWI-Prolog string 669% object, list of character codes or list of characters. 670% Finally, `term` maps to CVT_WRITE_CANONICAL. This implies that 671% arbitrary Prolog terms can be sent reliably using the option 672% list `[as(term),encoding(utf8)])`, using the same option list 673% for udp_receive/4. 674% 675% For example 676% 677% ``` 678% send(Host, Port, Message) :- 679% udp_socket(S), 680% udp_send(S, Message, Host:Port, []), 681% tcp_close_socket(S). 682% ``` 683% 684% A broadcast is achieved by using tcp_setopt(Socket, broadcast) 685% prior to sending the datagram and using the local network 686% broadcast address as a ip/4 term. 687 688 689 /******************************* 690 * OPTIONS * 691 *******************************/ 692 693%! tcp_setopt(+SocketId, +Option) is det. 694% 695% Set options on the socket. Defined options are: 696% 697% - reuseaddr 698% Allow servers to reuse a port without the system being 699% completely sure the port is no longer in use. 700% 701% - bindtodevice(+Device) 702% Bind the socket to Device (an atom). For example, the code 703% below binds the socket to the _loopback_ device that is 704% typically used to realise the _localhost_. See the manual 705% pages for setsockopt() and the socket interface (e.g., 706% socket(7) on Linux) for details. 707% 708% == 709% tcp_socket(Socket), 710% tcp_setopt(Socket, bindtodevice(lo)) 711% == 712% 713% - nodelay 714% - nodelay(true) 715% If =true=, disable the Nagle optimization on this socket, 716% which is enabled by default on almost all modern TCP/IP 717% stacks. The Nagle optimization joins small packages, which is 718% generally desirable, but sometimes not. Please note that the 719% underlying TCP_NODELAY setting to setsockopt() is not 720% available on all platforms and systems may require additional 721% privileges to change this option. If the option is not 722% supported, tcp_setopt/2 raises a domain_error exception. See 723% [Wikipedia](http://en.wikipedia.org/wiki/Nagle's_algorithm) 724% for details. 725% 726% - broadcast 727% UDP sockets only: broadcast the package to all addresses 728% matching the address. The address is normally the address of 729% the local subnet (i.e. 192.168.1.255). See udp_send/4. 730% 731% - ip_add_membership(+MultiCastGroup) 732% - ip_add_membership(+MultiCastGroup, +LocalInterface) 733% - ip_add_membership(+MultiCastGroup, +LocalInterface, +InterfaceIndex) 734% - ip_drop_membership(+MultiCastGroup) 735% - ip_drop_membership(+MultiCastGroup, +LocalInterface) 736% - ip_drop_membership(+MultiCastGroup, +LocalInterface, +InterfaceIndex) 737% Join/leave a multicast group. Calls setsockopt() with the 738% corresponding arguments. 739% 740% - dispatch(+Boolean) 741% In GUI environments (using XPCE or the Windows =swipl-win.exe= 742% executable) this flags defines whether or not any events are 743% dispatched on behalf of the user interface. Default is 744% =true=. Only very specific situations require setting 745% this to =false=. 746% 747% - sndbuf(+Integer) 748% Sets the send buffer size to Integer (bytes). On Windows this defaults 749% (now) to 64kb. Higher latency links may benefit from increasing this 750% further since the maximum theoretical throughput on a link is given by 751% buffer-size / latency. 752% See https://support.microsoft.com/en-gb/help/823764/slow-performance-occurs-when-you-copy-data-to-a-tcp-server-by-using-a 753% for Microsoft's discussion 754 755%! tcp_fcntl(+Stream, +Action, ?Argument) is det. 756% 757% Interface to the fcntl() call. Currently only suitable to deal 758% switch stream to non-blocking mode using: 759% 760% == 761% tcp_fcntl(Stream, setfl, nonblock), 762% == 763% 764% An attempt to read from a non-blocking stream while there is no 765% data available returns -1 (or =end_of_file= for read/1), but 766% at_end_of_stream/1 fails. On actual end-of-input, 767% at_end_of_stream/1 succeeds. 768 769tcp_fcntl(Socket, setfl, nonblock) :- 770 !, 771 tcp_setopt(Socket, nonblock). 772 773%! tcp_getopt(+Socket, ?Option) is semidet. 774% 775% Get information about Socket. Defined properties are below. 776% Requesting an unknown option results in a `domain_error` exception. 777% 778% - file_no(-File) 779% Get the OS file handle as an integer. This may be used for 780% debugging and integration. 781 782%! host_address(+HostName, -Address, +Options) is nondet. 783%! host_address(-HostName, +Address, +Options) is det. 784% 785% Translate between a machines host-name and it's (IP-)address. 786% Supported options: 787% 788% - domain(+Domain) 789% One of `inet` or `inet6` to limit the results to the given 790% family. 791% - type(+Type) 792% One of `stream` or `dgram`. 793% - canonname(+Boolean) 794% If `true` (default `false`), return the canonical host name 795% in the frist answer 796% 797% In mode (+,-,+) Address is unified to a dict with the following keys: 798% 799% - address 800% A Prolog terms describing the ip address. 801% - domain 802% One of `inet` or `inet6`. The underlying getaddrinfo() calls 803% this `family`. We use `domain` for consistency with 804% socket_create/2. 805% - type 806% Currently one of `stream` or `dgram`. 807% - host 808% Available if canonname(true) is specified on the first 809% returned address. Holds the official canonical host name. 810 811host_address(HostName, Address, Options), ground(HostName) => 812 '$host_address'(HostName, Addresses, Options), 813 member(Address, Addresses). 814host_address(HostName, Address, Options), is_dict(Address) => 815 '$host_address'(HostName, Address.address, Options). 816host_address(HostName, Address, Options), ground(Address) => 817 '$host_address'(HostName, Address, Options). 818 819%! tcp_host_to_address(?HostName, ?Address) is det. 820% 821% Translate between a machines host-name and it's (IP-)address. If 822% HostName is an atom, it is resolved using getaddrinfo() and the 823% IP-number is unified to Address using a term of the format 824% ip(Byte1,Byte2,Byte3,Byte4). Otherwise, if Address is bound to an 825% ip(Byte1,Byte2,Byte3,Byte4) term, it is resolved by gethostbyaddr() 826% and the canonical hostname is unified with HostName. 827% 828% @deprecated New code should use host_address/3. This version is 829% bootstrapped from host_address/3 and only searches for IP4 addresses 830% that support TCP connections. 831 832tcp_host_to_address(Host, Address), ground(Address) => 833 host_address(Host, Address, []). 834tcp_host_to_address(Host, Address), ground(Host) => 835 host_address(Host, [Dict|_], [domain(inet), type(stream)]), 836 Address = Dict.address. 837 838 839%! gethostname(-Hostname) is det. 840% 841% Return the canonical fully qualified name of this host. This is 842% achieved by calling gethostname() and return the canonical name 843% returned by getaddrinfo(). 844 845 846%! ip_name(?IP, ?Name) is det. 847% 848% Translate between the textual representation of an IP address and 849% the Prolog data structure. Prolog represents ip4 addresses as 850% ip(A,B,C,D) and ip6 addresses as ip(A,B,C,D,E,F,H). For example: 851% 852% ?- ip_name(ip(1,2,3,4), Name) 853% Name = '1.2.3.4'. 854% ?- ip_name(IP, '::'). 855% IP = ip(0,0,0,0,0,0,0,0). 856% ?- ip_name(IP, '1:2::3'). 857% IP = ip(1,2,0,0,0,0,0,3). 858 859ip_name(Ip, Atom), ground(Atom) => 860 name_to_ip(Atom, Ip). 861ip_name(Ip, Atom), ground(Ip) => 862 ip_to_name(Ip, Atom). 863ip_name(Ip, _) => 864 instantiation_error(Ip). 865 866name_to_ip(Atom, Ip4) :- 867 split_string(Atom, '.', '', Parts), 868 length(Parts, 4), 869 maplist(string_byte, Parts, Bytes), 870 !, 871 Ip4 =.. [ip|Bytes]. 872name_to_ip(Atom, Ip6) :- 873 split_string(Atom, ':', '', Parts0), 874 clean_ends(Parts0, Parts1), 875 length(Parts1, Len), 876 ( Len < 8 877 -> append(Pre, [""|Post], Parts1), 878 Zeros is 8-(Len-1), 879 length(ZList, Zeros), 880 maplist(=("0"), ZList), 881 append([Pre, ZList, Post], Parts) 882 ; Len == 8 883 -> Parts = Parts1 884 ), 885 !, 886 maplist(string_short, Parts, Shorts), 887 Ip6 =.. [ip|Shorts]. 888name_to_ip(Atom, _) :- 889 syntax_error(ip_address(Atom)). 890 891clean_ends([""|T0], T) :- 892 !, 893 ( append(T1, [""], T0) 894 -> T = T1 895 ; T = T0 896 ). 897clean_ends(T0, T) :- 898 append(T1, [""], T0), 899 !, 900 T = T1. 901clean_ends(T, T). 902 903string_byte(String, Byte) :- 904 number_string(Byte, String), 905 must_be(between(0, 255), Byte). 906 907string_short(String, Short) :- 908 string_concat('0x', String, String1), 909 number_string(Short, String1), 910 must_be(between(0, 65535), Short). 911 912ip_to_name(ip(A,B,C,D), Atom) :- 913 !, 914 atomic_list_concat([A,B,C,D], '.', Atom). 915ip_to_name(IP, Atom) :- 916 compound(IP), 917 compound_name_arity(IP, ip, 8), 918 !, 919 IP =.. [ip|Parts], 920 ( zero_seq(Parts, Pre, Post, Len), 921 Len > 1, 922 \+ ( zero_seq(Post, _, _, Len2), 923 Len2 > Len 924 ) 925 -> append([Pre, [''], Post], Parts1), 926 ( Pre == [] 927 -> Parts2 = [''|Parts1] 928 ; Parts2 = Parts1 929 ), 930 ( Post == [] 931 -> append(Parts2, [''], Parts3) 932 ; Parts3 = Parts2 933 ) 934 ; Parts3 = Parts 935 ), 936 maplist(to_hex, Parts3, Parts4), 937 atomic_list_concat(Parts4, ':', Atom). 938ip_to_name(IP, _) :- 939 domain_error(ip_address, IP). 940 941zero_seq(List, Pre, Post, Count) :- 942 append(Pre, [0|Post0], List), 943 leading_zeros(Post0, Post, 1, Count). 944 945leading_zeros([0|T0], T, C0, C) => 946 C1 is C0+1, 947 leading_zeros(T0, T, C1, C). 948leading_zeros(L0, L, C0, C) => 949 L = L0, 950 C = C0. 951 952to_hex('', '') :- 953 !. 954to_hex(Num, Hex) :- 955 format(string(Hex), '~16r', [Num]). 956 957 958 959 /******************************* 960 * SOCKS * 961 *******************************/ 962 963%! negotiate_socks_connection(+DesiredEndpoint, +StreamPair) is det. 964% 965% Negotiate a connection to DesiredEndpoint over StreamPair. 966% DesiredEndpoint should be in the form of either: 967% 968% * hostname : port 969% * ip(A,B,C,D) : port 970% 971% @error socks_error(Details) if the SOCKS negotiation failed. 972 973negotiate_socks_connection(Host:Port, StreamPair):- 974 format(StreamPair, '~s', [[0x5, % Version 5 975 0x1, % 1 auth method supported 976 0x0]]), % which is 'no auth' 977 flush_output(StreamPair), 978 get_byte(StreamPair, ServerVersion), 979 get_byte(StreamPair, AuthenticationMethod), 980 ( ServerVersion =\= 0x05 981 -> throw(error(socks_error(invalid_version(5, ServerVersion)), _)) 982 ; AuthenticationMethod =:= 0xff 983 -> throw(error(socks_error(invalid_authentication_method( 984 0xff, 985 AuthenticationMethod)), _)) 986 ; true 987 ), 988 ( Host = ip(A,B,C,D) 989 -> AddressType = 0x1, % IPv4 Address 990 format(atom(Address), '~s', [[A, B, C, D]]) 991 ; AddressType = 0x3, % Domain 992 atom_length(Host, Length), 993 format(atom(Address), '~s~w', [[Length], Host]) 994 ), 995 P1 is Port /\ 0xff, 996 P2 is Port >> 8, 997 format(StreamPair, '~s~w~s', [[0x5, % Version 5 998 0x1, % Please establish a connection 999 0x0, % reserved 1000 AddressType], 1001 Address, 1002 [P2, P1]]), 1003 flush_output(StreamPair), 1004 get_byte(StreamPair, _EchoedServerVersion), 1005 get_byte(StreamPair, Status), 1006 ( Status =:= 0 % Established! 1007 -> get_byte(StreamPair, _Reserved), 1008 get_byte(StreamPair, EchoedAddressType), 1009 ( EchoedAddressType =:= 0x1 1010 -> get_byte(StreamPair, _), % read IP4 1011 get_byte(StreamPair, _), 1012 get_byte(StreamPair, _), 1013 get_byte(StreamPair, _) 1014 ; get_byte(StreamPair, Length), % read host name 1015 forall(between(1, Length, _), 1016 get_byte(StreamPair, _)) 1017 ), 1018 get_byte(StreamPair, _), % read port 1019 get_byte(StreamPair, _) 1020 ; throw(error(socks_error(negotiation_rejected(Status)), _)) 1021 ). 1022 1023 1024 /******************************* 1025 * MESSAGES * 1026 *******************************/ 1027 1028/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1029The C-layer generates exceptions of the following format, where Message 1030is extracted from the operating system. 1031 1032 error(socket_error(Code, Message), _) 1033- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ 1034 1035:- multifile 1036 prolog:error_message//1. 1037 1038prologerror_message(socket_error(_Code, Message)) --> 1039 [ 'Socket error: ~w'-[Message] ]. 1040prologerror_message(socks_error(Error)) --> 1041 socks_error(Error). 1042prologerror_message(proxy_error(tried(Tried))) --> 1043 [ 'Failed to connect using a proxy. Tried:'-[], nl], 1044 proxy_tried(Tried). 1045 1046socks_error(invalid_version(Supported, Got)) --> 1047 [ 'SOCKS: unsupported version: ~p (supported: ~p)'- 1048 [ Got, Supported ] ]. 1049socks_error(invalid_authentication_method(Supported, Got)) --> 1050 [ 'SOCKS: unsupported authentication method: ~p (supported: ~p)'- 1051 [ Got, Supported ] ]. 1052socks_error(negotiation_rejected(Status)) --> 1053 [ 'SOCKS: connection failed: ~p'-[Status] ]. 1054 1055proxy_tried([]) --> []. 1056proxy_tried([H|T]) --> 1057 proxy_tried(H), 1058 proxy_tried(T). 1059proxy_tried(error(Proxy, Error)) --> 1060 [ '~w: '-[Proxy] ], 1061 '$messages':translate_message(Error). 1062proxy_tried(false(Proxy)) --> 1063 [ '~w: failed with unspecified error'-[Proxy] ]