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79ef79ee AW |
1 | ;;; Web server |
2 | ||
8cb9a30c | 3 | ;; Copyright (C) 2010, 2011, 2012, 2013 Free Software Foundation, Inc. |
79ef79ee AW |
4 | |
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. | |
9 | ;; | |
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. | |
14 | ;; | |
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 | |
18 | ;; 02110-1301 USA | |
19 | ||
20 | ;;; Commentary: | |
21 | ;;; | |
22 | ;;; (web server) is a generic web server interface, along with a main | |
23 | ;;; loop implementation for web servers controlled by Guile. | |
24 | ;;; | |
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. | |
31 | ;;; | |
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. | |
38 | ;;; | |
39 | ;;; The life cycle of a server goes as follows: | |
40 | ;;; | |
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. | |
44 | ;;; | |
45 | ;;; * The `read' hook is called, to read a request from a new client. | |
462a1a04 AW |
46 | ;;; The `read' hook takes one arguments, the server socket. It |
47 | ;;; should return three values: an opaque client socket, the | |
79ef79ee AW |
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. | |
51 | ;;; | |
79ef79ee AW |
52 | ;;; If the read failed, the `read' hook may return #f for the client |
53 | ;;; socket, request, and body. | |
54 | ;;; | |
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. | |
62 | ;;; | |
63 | ;;; * The `write' hook is called with three arguments: the client | |
462a1a04 AW |
64 | ;;; socket, the response, and the body. The `write' hook returns no |
65 | ;;; values. | |
79ef79ee AW |
66 | ;;; |
67 | ;;; * At this point the request handling is complete. For a loop, we | |
462a1a04 | 68 | ;;; loop back and try to read a new request. |
79ef79ee AW |
69 | ;;; |
70 | ;;; * If the user interrupts the loop, the `close' hook is called on | |
71 | ;;; the server socket. | |
72 | ;;; | |
73 | ;;; Code: | |
74 | ||
75 | (define-module (web server) | |
76 | #:use-module (srfi srfi-9) | |
76702cdc | 77 | #:use-module (srfi srfi-9 gnu) |
79ef79ee | 78 | #:use-module (rnrs bytevectors) |
6854c324 | 79 | #:use-module (ice-9 binary-ports) |
79ef79ee AW |
80 | #:use-module (web request) |
81 | #:use-module (web response) | |
82 | #:use-module (system repl error-handling) | |
83 | #:use-module (ice-9 control) | |
8cb9a30c | 84 | #:use-module (ice-9 iconv) |
79ef79ee AW |
85 | #:export (define-server-impl |
86 | lookup-server-impl | |
87 | open-server | |
88 | read-client | |
89 | handle-request | |
90 | sanitize-response | |
91 | write-client | |
92 | close-server | |
93 | serve-one-client | |
94 | run-server)) | |
95 | ||
8bf6cfea AW |
96 | (define *timer* (gettimeofday)) |
97 | (define (print-elapsed who) | |
98 | (let ((t (gettimeofday))) | |
99 | (pk who (+ (* (- (car t) (car *timer*)) 1000000) | |
100 | (- (cdr t) (cdr *timer*)))) | |
101 | (set! *timer* t))) | |
102 | ||
103 | (eval-when (expand) | |
104 | (define *time-debug?* #f)) | |
105 | ||
106 | (define-syntax debug-elapsed | |
107 | (lambda (x) | |
108 | (syntax-case x () | |
109 | ((_ who) | |
110 | (if *time-debug?* | |
111 | #'(print-elapsed who) | |
112 | #'*unspecified*))))) | |
113 | ||
79ef79ee AW |
114 | (define-record-type server-impl |
115 | (make-server-impl name open read write close) | |
116 | server-impl? | |
117 | (name server-impl-name) | |
118 | (open server-impl-open) | |
119 | (read server-impl-read) | |
120 | (write server-impl-write) | |
121 | (close server-impl-close)) | |
122 | ||
0c65f52c AW |
123 | (define-syntax-rule (define-server-impl name open read write close) |
124 | (define name | |
125 | (make-server-impl 'name open read write close))) | |
79ef79ee AW |
126 | |
127 | (define (lookup-server-impl impl) | |
06883ae0 | 128 | "Look up a server implementation. If IMPL is a server |
43d6659a | 129 | implementation already, it is returned directly. If it is a symbol, the |
06883ae0 | 130 | binding named IMPL in the ‘(web server IMPL)’ module is |
43d6659a AW |
131 | looked up. Otherwise an error is signaled. |
132 | ||
133 | Currently a server implementation is a somewhat opaque type, useful only | |
134 | for passing to other procedures in this module, like | |
06883ae0 | 135 | ‘read-client’." |
79ef79ee AW |
136 | (cond |
137 | ((server-impl? impl) impl) | |
138 | ((symbol? impl) | |
139 | (let ((impl (module-ref (resolve-module `(web server ,impl)) impl))) | |
140 | (if (server-impl? impl) | |
141 | impl | |
142 | (error "expected a server impl in module" `(web server ,impl))))) | |
143 | (else | |
144 | (error "expected a server-impl or a symbol" impl)))) | |
145 | ||
146 | ;; -> server | |
147 | (define (open-server impl open-params) | |
06883ae0 DH |
148 | "Open a server for the given implementation. Return one value, the |
149 | new server object. The implementation's ‘open’ procedure is | |
150 | applied to OPEN-PARAMS, which should be a list." | |
79ef79ee AW |
151 | (apply (server-impl-open impl) open-params)) |
152 | ||
462a1a04 AW |
153 | ;; -> (client request body | #f #f #f) |
154 | (define (read-client impl server) | |
06883ae0 DH |
155 | "Read a new client from SERVER, by applying the implementation's |
156 | ‘read’ procedure to the server. If successful, return three | |
43d6659a | 157 | values: an object corresponding to the client, a request object, and the |
06883ae0 | 158 | request body. If any exception occurs, return ‘#f’ for all three |
43d6659a | 159 | values." |
79ef79ee AW |
160 | (call-with-error-handling |
161 | (lambda () | |
462a1a04 | 162 | ((server-impl-read impl) server)) |
79ef79ee | 163 | #:pass-keys '(quit interrupt) |
2263ccb5 AW |
164 | #:on-error (if (batch-mode?) 'backtrace 'debug) |
165 | #:post-error (lambda _ (values #f #f #f)))) | |
79ef79ee | 166 | |
f944ee8f | 167 | (define (extend-response r k v . additional) |
3c12fc35 AW |
168 | (define (extend-alist alist k v) |
169 | (let ((pair (assq k alist))) | |
170 | (acons k v (if pair (delq pair alist) alist)))) | |
76702cdc | 171 | (let ((r (set-field r (response-headers) |
c04bf433 | 172 | (extend-alist (response-headers r) k v)))) |
f944ee8f AW |
173 | (if (null? additional) |
174 | r | |
175 | (apply extend-response r additional)))) | |
176 | ||
79ef79ee AW |
177 | ;; -> response body |
178 | (define (sanitize-response request response body) | |
43d6659a AW |
179 | "\"Sanitize\" the given response and body, making them appropriate for |
180 | the given request. | |
181 | ||
06883ae0 | 182 | As a convenience to web handler authors, RESPONSE may be given as |
43d6659a AW |
183 | an alist of headers, in which case it is used to construct a default |
184 | response. Ensures that the response version corresponds to the request | |
06883ae0 DH |
185 | version. If BODY is a string, encodes the string to a bytevector, |
186 | in an encoding appropriate for RESPONSE. Adds a | |
187 | ‘content-length’ and ‘content-type’ header, as necessary. | |
43d6659a | 188 | |
06883ae0 | 189 | If BODY is a procedure, it is called with a port as an argument, |
43d6659a AW |
190 | and the output collected as a bytevector. In the future we might try to |
191 | instead use a compressing, chunk-encoded port, and call this procedure | |
192 | later, in the write-client procedure. Authors are advised not to rely | |
193 | on the procedure being called at any particular time." | |
d9f00c3d AW |
194 | (cond |
195 | ((list? response) | |
c6371902 AW |
196 | (sanitize-response request |
197 | (build-response #:version (request-version request) | |
198 | #:headers response) | |
199 | body)) | |
200 | ((not (equal? (request-version request) (response-version response))) | |
201 | (sanitize-response request | |
202 | (adapt-response-version response | |
203 | (request-version request)) | |
204 | body)) | |
a4342ba8 AW |
205 | ((not body) |
206 | (values response #vu8())) | |
d9f00c3d AW |
207 | ((string? body) |
208 | (let* ((type (response-content-type response | |
0acc595b AW |
209 | '(text/plain))) |
210 | (declared-charset (assq-ref (cdr type) 'charset)) | |
af0da6eb | 211 | (charset (or declared-charset "utf-8"))) |
d9f00c3d AW |
212 | (sanitize-response |
213 | request | |
214 | (if declared-charset | |
215 | response | |
216 | (extend-response response 'content-type | |
0acc595b | 217 | `(,@type (charset . ,charset)))) |
8cb9a30c | 218 | (string->bytevector body charset)))) |
d9f00c3d | 219 | ((procedure? body) |
af0da6eb | 220 | (let* ((type (response-content-type response |
0acc595b AW |
221 | '(text/plain))) |
222 | (declared-charset (assq-ref (cdr type) 'charset)) | |
af0da6eb AW |
223 | (charset (or declared-charset "utf-8"))) |
224 | (sanitize-response | |
225 | request | |
226 | (if declared-charset | |
227 | response | |
228 | (extend-response response 'content-type | |
0acc595b | 229 | `(,@type (charset . ,charset)))) |
af0da6eb | 230 | (call-with-encoded-output-string charset body)))) |
164a78b3 AW |
231 | ((not (bytevector? body)) |
232 | (error "unexpected body type")) | |
eec3a508 AW |
233 | ((and (response-must-not-include-body? response) |
234 | body | |
3b2226ec | 235 | ;; FIXME make this stricter: even an empty body should be prohibited. |
eec3a508 | 236 | (not (zero? (bytevector-length body)))) |
164a78b3 AW |
237 | (error "response with this status code must not include body" response)) |
238 | (else | |
d9f00c3d | 239 | ;; check length; assert type; add other required fields? |
a4342ba8 AW |
240 | (values (let ((rlen (response-content-length response)) |
241 | (blen (bytevector-length body))) | |
242 | (cond | |
612aa5be AW |
243 | (rlen (if (= rlen blen) |
244 | response | |
245 | (error "bad content-length" rlen blen))) | |
a4342ba8 | 246 | (else (extend-response response 'content-length blen)))) |
164a78b3 AW |
247 | (if (eq? (request-method request) 'HEAD) |
248 | ;; Responses to HEAD requests must not include bodies. | |
249 | ;; We could raise an error here, but it seems more | |
250 | ;; appropriate to just do something sensible. | |
251 | #f | |
252 | body))))) | |
79ef79ee | 253 | |
c6371902 AW |
254 | ;; -> response body state |
255 | (define (handle-request handler request body state) | |
43d6659a AW |
256 | "Handle a given request, returning the response and body. |
257 | ||
258 | The response and response body are produced by calling the given | |
06883ae0 | 259 | HANDLER with REQUEST and BODY as arguments. |
43d6659a | 260 | |
06883ae0 | 261 | The elements of STATE are also passed to HANDLER as |
43d6659a | 262 | arguments, and may be returned as additional values. The new |
06883ae0 | 263 | STATE, collected from the HANDLER's return values, is then |
43d6659a AW |
264 | returned as a list. The idea is that a server loop receives a handler |
265 | from the user, along with whatever state values the user is interested | |
266 | in, allowing the user's handler to explicitly manage its state." | |
c6371902 AW |
267 | (call-with-error-handling |
268 | (lambda () | |
269 | (call-with-values (lambda () | |
270 | (with-stack-and-prompt | |
271 | (lambda () | |
272 | (apply handler request body state)))) | |
273 | (lambda (response body . state) | |
274 | (call-with-values (lambda () | |
8bf6cfea | 275 | (debug-elapsed 'handler) |
c6371902 AW |
276 | (sanitize-response request response body)) |
277 | (lambda (response body) | |
8bf6cfea | 278 | (debug-elapsed 'sanitize) |
c6371902 AW |
279 | (values response body state)))))) |
280 | #:pass-keys '(quit interrupt) | |
2263ccb5 AW |
281 | #:on-error (if (batch-mode?) 'backtrace 'debug) |
282 | #:post-error (lambda _ | |
283 | (values (build-response #:code 500) #f state)))) | |
c6371902 | 284 | |
462a1a04 | 285 | ;; -> unspecified values |
79ef79ee | 286 | (define (write-client impl server client response body) |
06883ae0 | 287 | "Write an HTTP response and body to CLIENT. If the server and |
43d6659a AW |
288 | client support persistent connections, it is the implementation's |
289 | responsibility to keep track of the client thereafter, presumably by | |
06883ae0 | 290 | attaching it to the SERVER argument somehow." |
79ef79ee AW |
291 | (call-with-error-handling |
292 | (lambda () | |
293 | ((server-impl-write impl) server client response body)) | |
294 | #:pass-keys '(quit interrupt) | |
2263ccb5 AW |
295 | #:on-error (if (batch-mode?) 'backtrace 'debug) |
296 | #:post-error (lambda _ (values)))) | |
79ef79ee AW |
297 | |
298 | ;; -> unspecified values | |
299 | (define (close-server impl server) | |
43d6659a | 300 | "Release resources allocated by a previous invocation of |
06883ae0 | 301 | ‘open-server’." |
79ef79ee AW |
302 | ((server-impl-close impl) server)) |
303 | ||
304 | (define call-with-sigint | |
305 | (if (not (provided? 'posix)) | |
306 | (lambda (thunk handler-thunk) (thunk)) | |
307 | (lambda (thunk handler-thunk) | |
308 | (let ((handler #f)) | |
309 | (catch 'interrupt | |
310 | (lambda () | |
311 | (dynamic-wind | |
312 | (lambda () | |
313 | (set! handler | |
314 | (sigaction SIGINT (lambda (sig) (throw 'interrupt))))) | |
315 | thunk | |
316 | (lambda () | |
317 | (if handler | |
318 | ;; restore Scheme handler, SIG_IGN or SIG_DFL. | |
319 | (sigaction SIGINT (car handler) (cdr handler)) | |
320 | ;; restore original C handler. | |
321 | (sigaction SIGINT #f))))) | |
322 | (lambda (k . _) (handler-thunk))))))) | |
323 | ||
324 | (define (with-stack-and-prompt thunk) | |
325 | (call-with-prompt (default-prompt-tag) | |
326 | (lambda () (start-stack #t (thunk))) | |
327 | (lambda (k proc) | |
328 | (with-stack-and-prompt (lambda () (proc k)))))) | |
329 | ||
462a1a04 AW |
330 | ;; -> new-state |
331 | (define (serve-one-client handler impl server state) | |
06883ae0 DH |
332 | "Read one request from SERVER, call HANDLER on the request |
333 | and body, and write the response to the client. Return the new state | |
43d6659a | 334 | produced by the handler procedure." |
8bf6cfea | 335 | (debug-elapsed 'serve-again) |
79ef79ee AW |
336 | (call-with-values |
337 | (lambda () | |
462a1a04 AW |
338 | (read-client impl server)) |
339 | (lambda (client request body) | |
8bf6cfea | 340 | (debug-elapsed 'read-client) |
79ef79ee AW |
341 | (if client |
342 | (call-with-values | |
343 | (lambda () | |
c6371902 AW |
344 | (handle-request handler request body state)) |
345 | (lambda (response body state) | |
8bf6cfea | 346 | (debug-elapsed 'handle-request) |
462a1a04 AW |
347 | (write-client impl server client response body) |
348 | (debug-elapsed 'write-client) | |
349 | state)) | |
350 | state)))) | |
79ef79ee AW |
351 | |
352 | (define* (run-server handler #:optional (impl 'http) (open-params '()) | |
353 | . state) | |
43d6659a AW |
354 | "Run Guile's built-in web server. |
355 | ||
06883ae0 | 356 | HANDLER should be a procedure that takes two or more arguments, |
43d6659a AW |
357 | the HTTP request and request body, and returns two or more values, the |
358 | response and response body. | |
359 | ||
360 | For example, here is a simple \"Hello, World!\" server: | |
361 | ||
362 | @example | |
363 | (define (handler request body) | |
0acc595b | 364 | (values '((content-type . (text/plain))) |
43d6659a AW |
365 | \"Hello, World!\")) |
366 | (run-server handler) | |
367 | @end example | |
368 | ||
06883ae0 | 369 | The response and body will be run through ‘sanitize-response’ |
43d6659a AW |
370 | before sending back to the client. |
371 | ||
06883ae0 DH |
372 | Additional arguments to HANDLER are taken from |
373 | STATE. Additional return values are accumulated into a new | |
374 | STATE, which will be used for subsequent requests. In this way a | |
43d6659a AW |
375 | handler can explicitly manage its state. |
376 | ||
06883ae0 DH |
377 | The default server implementation is ‘http’, which accepts |
378 | OPEN-PARAMS like ‘(#:port 8081)’, among others. See \"Web | |
43d6659a | 379 | Server\" in the manual, for more information." |
79ef79ee AW |
380 | (let* ((impl (lookup-server-impl impl)) |
381 | (server (open-server impl open-params))) | |
382 | (call-with-sigint | |
383 | (lambda () | |
462a1a04 AW |
384 | (let lp ((state state)) |
385 | (lp (serve-one-client handler impl server state)))) | |
79ef79ee AW |
386 | (lambda () |
387 | (close-server impl server) | |
388 | (values))))) |