3 ;; Copyright (C) 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
5 ;; This library is free software; you can redistribute it and/or
6 ;; modify it under the terms of the GNU Lesser General Public
7 ;; License as published by the Free Software Foundation; either
8 ;; version 3 of the License, or (at your option) any later version.
10 ;; This library is distributed in the hope that it will be useful,
11 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
12 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 ;; Lesser General Public License for more details.
15 ;; You should have received a copy of the GNU Lesser General Public
16 ;; License along with this library; if not, write to the Free Software
17 ;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
22 ;;; (web server) is a generic web server interface, along with a main
23 ;;; loop implementation for web servers controlled by Guile.
25 ;;; The lowest layer is the <server-impl> object, which defines a set of
26 ;;; hooks to open a server, read a request from a client, write a
27 ;;; response to a client, and close a server. These hooks -- open,
28 ;;; read, write, and close, respectively -- are bound together in a
29 ;;; <server-impl> object. Procedures in this module take a
30 ;;; <server-impl> object, if needed.
32 ;;; A <server-impl> may also be looked up by name. If you pass the
33 ;;; `http' symbol to `run-server', Guile looks for a variable named
34 ;;; `http' in the `(web server http)' module, which should be bound to a
35 ;;; <server-impl> object. Such a binding is made by instantiation of
36 ;;; the `define-server-impl' syntax. In this way the run-server loop can
37 ;;; automatically load other backends if available.
39 ;;; The life cycle of a server goes as follows:
41 ;;; * The `open' hook is called, to open the server. `open' takes 0 or
42 ;;; more arguments, depending on the backend, and returns an opaque
43 ;;; server socket object, or signals an error.
45 ;;; * The `read' hook is called, to read a request from a new client.
46 ;;; The `read' hook takes one arguments, the server socket. It
47 ;;; should return three values: an opaque client socket, the
48 ;;; request, and the request body. The request should be a
49 ;;; `<request>' object, from `(web request)'. The body should be a
50 ;;; string or a bytevector, or `#f' if there is no body.
52 ;;; If the read failed, the `read' hook may return #f for the client
53 ;;; socket, request, and body.
55 ;;; * A user-provided handler procedure is called, with the request
56 ;;; and body as its arguments. The handler should return two
57 ;;; values: the response, as a `<response>' record from `(web
58 ;;; response)', and the response body as a string, bytevector, or
59 ;;; `#f' if not present. We also allow the reponse to be simply an
60 ;;; alist of headers, in which case a default response object is
61 ;;; constructed with those headers.
63 ;;; * The `write' hook is called with three arguments: the client
64 ;;; socket, the response, and the body. The `write' hook returns no
67 ;;; * At this point the request handling is complete. For a loop, we
68 ;;; loop back and try to read a new request.
70 ;;; * If the user interrupts the loop, the `close' hook is called on
71 ;;; the server socket.
75 (define-module (web server)
76 #:use-module (srfi srfi-9)
77 #:use-module (rnrs bytevectors)
78 #:use-module (ice-9 binary-ports)
79 #:use-module (web request)
80 #:use-module (web response)
81 #:use-module (system repl error-handling)
82 #:use-module (ice-9 control)
83 #:use-module (ice-9 iconv)
84 #:export (define-server-impl
95 (define *timer* (gettimeofday))
96 (define (print-elapsed who)
97 (let ((t (gettimeofday)))
98 (pk who (+ (* (- (car t) (car *timer*)) 1000000)
99 (- (cdr t) (cdr *timer*))))
103 (define *time-debug?* #f))
105 (define-syntax debug-elapsed
110 #'(print-elapsed who)
113 (define-record-type server-impl
114 (make-server-impl name open read write close)
116 (name server-impl-name)
117 (open server-impl-open)
118 (read server-impl-read)
119 (write server-impl-write)
120 (close server-impl-close))
122 (define-syntax-rule (define-server-impl name open read write close)
124 (make-server-impl 'name open read write close)))
126 (define (lookup-server-impl impl)
127 "Look up a server implementation. If IMPL is a server
128 implementation already, it is returned directly. If it is a symbol, the
129 binding named IMPL in the ‘(web server IMPL)’ module is
130 looked up. Otherwise an error is signaled.
132 Currently a server implementation is a somewhat opaque type, useful only
133 for passing to other procedures in this module, like
136 ((server-impl? impl) impl)
138 (let ((impl (module-ref (resolve-module `(web server ,impl)) impl)))
139 (if (server-impl? impl)
141 (error "expected a server impl in module" `(web server ,impl)))))
143 (error "expected a server-impl or a symbol" impl))))
146 (define (open-server impl open-params)
147 "Open a server for the given implementation. Return one value, the
148 new server object. The implementation's ‘open’ procedure is
149 applied to OPEN-PARAMS, which should be a list."
150 (apply (server-impl-open impl) open-params))
152 ;; -> (client request body | #f #f #f)
153 (define (read-client impl server)
154 "Read a new client from SERVER, by applying the implementation's
155 ‘read’ procedure to the server. If successful, return three
156 values: an object corresponding to the client, a request object, and the
157 request body. If any exception occurs, return ‘#f’ for all three
159 (call-with-error-handling
161 ((server-impl-read impl) server))
162 #:pass-keys '(quit interrupt)
163 #:on-error (if (batch-mode?) 'backtrace 'debug)
164 #:post-error (lambda _ (values #f #f #f))))
166 (define (extend-response r k v . additional)
167 (define (extend-alist alist k v)
168 (let ((pair (assq k alist)))
169 (acons k v (if pair (delq pair alist) alist))))
170 (let ((r (build-response #:version (response-version r)
171 #:code (response-code r)
173 (extend-alist (response-headers r) k v)
174 #:port (response-port r))))
175 (if (null? additional)
177 (apply extend-response r additional))))
180 (define (sanitize-response request response body)
181 "\"Sanitize\" the given response and body, making them appropriate for
184 As a convenience to web handler authors, RESPONSE may be given as
185 an alist of headers, in which case it is used to construct a default
186 response. Ensures that the response version corresponds to the request
187 version. If BODY is a string, encodes the string to a bytevector,
188 in an encoding appropriate for RESPONSE. Adds a
189 ‘content-length’ and ‘content-type’ header, as necessary.
191 If BODY is a procedure, it is called with a port as an argument,
192 and the output collected as a bytevector. In the future we might try to
193 instead use a compressing, chunk-encoded port, and call this procedure
194 later, in the write-client procedure. Authors are advised not to rely
195 on the procedure being called at any particular time."
198 (sanitize-response request
199 (build-response #:version (request-version request)
202 ((not (equal? (request-version request) (response-version response)))
203 (sanitize-response request
204 (adapt-response-version response
205 (request-version request))
208 (values response #vu8()))
210 (let* ((type (response-content-type response
212 (declared-charset (assq-ref (cdr type) 'charset))
213 (charset (or declared-charset "utf-8")))
218 (extend-response response 'content-type
219 `(,@type (charset . ,charset))))
220 (string->bytevector body charset))))
222 (let* ((type (response-content-type response
224 (declared-charset (assq-ref (cdr type) 'charset))
225 (charset (or declared-charset "utf-8")))
230 (extend-response response 'content-type
231 `(,@type (charset . ,charset))))
232 (call-with-encoded-output-string charset body))))
233 ((not (bytevector? body))
234 (error "unexpected body type"))
235 ((and (response-must-not-include-body? response)
237 (not (zero? (bytevector-length body))))
238 (error "response with this status code must not include body" response))
240 ;; check length; assert type; add other required fields?
241 (values (let ((rlen (response-content-length response))
242 (blen (bytevector-length body)))
244 (rlen (if (= rlen blen)
246 (error "bad content-length" rlen blen)))
247 ((zero? blen) response)
248 (else (extend-response response 'content-length blen))))
249 (if (eq? (request-method request) 'HEAD)
250 ;; Responses to HEAD requests must not include bodies.
251 ;; We could raise an error here, but it seems more
252 ;; appropriate to just do something sensible.
256 ;; -> response body state
257 (define (handle-request handler request body state)
258 "Handle a given request, returning the response and body.
260 The response and response body are produced by calling the given
261 HANDLER with REQUEST and BODY as arguments.
263 The elements of STATE are also passed to HANDLER as
264 arguments, and may be returned as additional values. The new
265 STATE, collected from the HANDLER's return values, is then
266 returned as a list. The idea is that a server loop receives a handler
267 from the user, along with whatever state values the user is interested
268 in, allowing the user's handler to explicitly manage its state."
269 (call-with-error-handling
271 (call-with-values (lambda ()
272 (with-stack-and-prompt
274 (apply handler request body state))))
275 (lambda (response body . state)
276 (call-with-values (lambda ()
277 (debug-elapsed 'handler)
278 (sanitize-response request response body))
279 (lambda (response body)
280 (debug-elapsed 'sanitize)
281 (values response body state))))))
282 #:pass-keys '(quit interrupt)
283 #:on-error (if (batch-mode?) 'backtrace 'debug)
284 #:post-error (lambda _
285 (values (build-response #:code 500) #f state))))
287 ;; -> unspecified values
288 (define (write-client impl server client response body)
289 "Write an HTTP response and body to CLIENT. If the server and
290 client support persistent connections, it is the implementation's
291 responsibility to keep track of the client thereafter, presumably by
292 attaching it to the SERVER argument somehow."
293 (call-with-error-handling
295 ((server-impl-write impl) server client response body))
296 #:pass-keys '(quit interrupt)
297 #:on-error (if (batch-mode?) 'backtrace 'debug)
298 #:post-error (lambda _ (values))))
300 ;; -> unspecified values
301 (define (close-server impl server)
302 "Release resources allocated by a previous invocation of
304 ((server-impl-close impl) server))
306 (define call-with-sigint
307 (if (not (provided? 'posix))
308 (lambda (thunk handler-thunk) (thunk))
309 (lambda (thunk handler-thunk)
316 (sigaction SIGINT (lambda (sig) (throw 'interrupt)))))
320 ;; restore Scheme handler, SIG_IGN or SIG_DFL.
321 (sigaction SIGINT (car handler) (cdr handler))
322 ;; restore original C handler.
323 (sigaction SIGINT #f)))))
324 (lambda (k . _) (handler-thunk)))))))
326 (define (with-stack-and-prompt thunk)
327 (call-with-prompt (default-prompt-tag)
328 (lambda () (start-stack #t (thunk)))
330 (with-stack-and-prompt (lambda () (proc k))))))
333 (define (serve-one-client handler impl server state)
334 "Read one request from SERVER, call HANDLER on the request
335 and body, and write the response to the client. Return the new state
336 produced by the handler procedure."
337 (debug-elapsed 'serve-again)
340 (read-client impl server))
341 (lambda (client request body)
342 (debug-elapsed 'read-client)
346 (handle-request handler request body state))
347 (lambda (response body state)
348 (debug-elapsed 'handle-request)
349 (write-client impl server client response body)
350 (debug-elapsed 'write-client)
354 (define* (run-server handler #:optional (impl 'http) (open-params '())
356 "Run Guile's built-in web server.
358 HANDLER should be a procedure that takes two or more arguments,
359 the HTTP request and request body, and returns two or more values, the
360 response and response body.
362 For example, here is a simple \"Hello, World!\" server:
365 (define (handler request body)
366 (values '((content-type . (text/plain)))
371 The response and body will be run through ‘sanitize-response’
372 before sending back to the client.
374 Additional arguments to HANDLER are taken from
375 STATE. Additional return values are accumulated into a new
376 STATE, which will be used for subsequent requests. In this way a
377 handler can explicitly manage its state.
379 The default server implementation is ‘http’, which accepts
380 OPEN-PARAMS like ‘(#:port 8081)’, among others. See \"Web
381 Server\" in the manual, for more information."
382 (let* ((impl (lookup-server-impl impl))
383 (server (open-server impl open-params)))
386 (let lp ((state state))
387 (lp (serve-one-client handler impl server state))))
389 (close-server impl server)