;;; guile-websocket --- WebSocket client/server ;;; Copyright © 2015 David Thompson ;;; Copyright © 2017 Christopher Allan Webber ;;; ;;; This file is part of guile-websocket. ;;; ;;; Guile-websocket is free software; you can redistribute it and/or modify ;;; it under the terms of the GNU Lesser General Public License as ;;; published by the Free Software Foundation; either version 3 of the ;;; License, or (at your option) any later version. ;;; ;;; Guile-websocket is distributed in the hope that it will be useful, ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ;;; Lesser General Public License for more details. ;;; ;;; You should have received a copy of the GNU Lesser General Public ;;; License along with guile-websocket. If not, see ;;; . ;;; Commentary: ;; ;; WebSocket server. ;; ;;; Code: (define-module (8sync systems websocket server) #:use-module (ice-9 match) #:use-module (rnrs bytevectors) #:use-module (rnrs io ports) #:use-module (web request) #:use-module (web response) #:use-module (web uri) #:use-module (oop goops) #:use-module (8sync) #:use-module (8sync ports) #:use-module (8sync systems web) #:use-module (8sync systems websocket frame) #:use-module (8sync systems websocket utils) #:export ( .websocket-handler)) ;; See section 4.2 for explanation of the handshake. (define (read-handshake-request client-socket) "Read HTTP request from CLIENT-SOCKET that should contain the headers required for a WebSocket handshake." ;; See section 4.2.1. (read-request client-socket)) (define (make-handshake-response client-key) "Return an HTTP response object for upgrading to a WebSocket connection for the client whose key is CLIENT-KEY, a base64 encoded string." ;; See section 4.2.2. (let ((accept-key (make-accept-key (string-trim-both client-key)))) (build-response #:code 101 #:headers `((upgrade . ("websocket")) (connection . (upgrade)) (sec-websocket-accept . ,accept-key))))) (define no-op (const #f)) (define (make-simple-counter) (let ((count 0)) (lambda () (set! count (1+ count)) count))) (define-actor () ((ws-send websocket-server-send)) (upgrade-paths #:init-value `(("websocket" . ,(wrap-apply websocket-client-loop))) #:allocation #:each-subclass #:accessor .upgrade-paths) (gen-client-id #:init-thunk make-simple-counter) ;; active websocket connections (ws-clients #:init-thunk make-hash-table #:accessor .ws-clients) (on-ws-message #:init-keyword #:on-ws-message #:getter .on-ws-message) (on-ws-client-connect #:init-keyword #:on-ws-client-connect #:init-value no-op #:getter .on-ws-client-connect) (on-ws-client-disconnect #:init-keyword #:on-ws-client-disconnect #:init-value no-op #:getter .on-ws-client-disconnect)) (define (web-server-gen-client-id websocket-server) ((slot-ref websocket-server 'gen-client-id))) (define (websocket-client-loop websocket-server client request body) "Serve client connected via CLIENT by performing the HTTP handshake and listening for control and data frames. HANDLER is called for each complete message that is received." ;; TODO: We'll also want to handle stuff like the sub-protocol. (define (handle-data-frame type data) ((.on-ws-message websocket-server) websocket-server client-id (match type ('text (utf8->string data)) ('binary data)))) (define (read-frame-maybe) (and (not (eof-object? (lookahead-u8 client))) (read-frame client))) ;; Allows other actors to send things to this specific client ;; @@: We probably could just increment a counter... (define client-id (web-server-gen-client-id websocket-server)) (define (close-down) (close-port client) (hash-remove! (.ws-clients websocket-server) client-id) ((.on-ws-client-disconnect websocket-server) websocket-server client-id)) (hash-set! (.ws-clients websocket-server) client-id client) ;; Disable buffering for websockets (setvbuf client 'none) ((.on-ws-client-connect websocket-server) websocket-server client-id) ;; Perform the HTTP handshake and upgrade to WebSocket protocol. (let* ((client-key (assoc-ref (request-headers request) 'sec-websocket-key)) (response (make-handshake-response client-key))) (write-response response client) (let loop ((fragments '()) (type #f)) (let ((frame (read-frame-maybe))) (cond ;; EOF - port is closed. ((not frame) (close-down)) ;; Per section 5.4, control frames may appear interspersed ;; along with a fragmented message. ((close-frame? frame) ;; Per section 5.5.1, echo the close frame back to the ;; client before closing the socket. The client may no ;; longer be listening. (false-if-exception (write-frame (make-close-frame (frame-data frame)) client)) (close-down)) ((ping-frame? frame) ;; Per section 5.5.3, a pong frame must include the exact ;; same data as the ping frame. (write-frame (make-pong-frame (frame-data frame)) client) (loop fragments type)) ((pong-frame? frame) ; silently ignore pongs (loop fragments type)) ((first-fragment-frame? frame) ; begin accumulating fragments (loop (list frame) (frame-type frame))) ((final-fragment-frame? frame) ; concatenate all fragments (handle-data-frame type (frame-concatenate (reverse fragments))) (loop '() #f)) ((fragment-frame? frame) ; add a fragment (loop (cons frame fragments) type)) ((data-frame? frame) ; unfragmented data frame (handle-data-frame (frame-type frame) (frame-data frame)) (loop '() #f))))))) (define (websocket-server-send websocket-server message client-id data) (cond ((hash-ref (.ws-clients websocket-server) client-id) => (lambda (client) (write-frame (cond ((string? data) (make-text-frame data)) ((bytevector? data) (make-binary-frame data))) client) ;; ok is like success, amirite (<-reply message 'ok))) (else ;; No such client with that id. ;; Either it closed, or it was never there. (<-reply message 'client-gone))))