1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
|
;;;; (web uri) --- URI manipulation tools
;;;;
;;;; Copyright (C) 1997,2001,2002,2010,2011,2012,2013 Free Software Foundation, Inc.
;;;;
;;;; This library 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.
;;;;
;;;; This library 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 this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;;;
;;; Commentary:
;; A data type for Universal Resource Identifiers, as defined in RFC
;; 3986.
;;; Code:
(define-module (web uri)
#:use-module (srfi srfi-9)
#:use-module (ice-9 regex)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 control)
#:use-module (rnrs bytevectors)
#:use-module (ice-9 binary-ports)
#:export (uri?
uri-scheme uri-userinfo uri-host uri-port
uri-path uri-query uri-fragment
build-uri
declare-default-port!
string->uri uri->string
uri-decode uri-encode
split-and-decode-uri-path
encode-and-join-uri-path))
(define-record-type <uri>
(make-uri scheme userinfo host port path query fragment)
uri?
(scheme uri-scheme)
(userinfo uri-userinfo)
(host uri-host)
(port uri-port)
(path uri-path)
(query uri-query)
(fragment uri-fragment))
(define (absolute-uri? obj)
(and (uri? obj) (uri-scheme obj) #t))
(define (uri-error message . args)
(throw 'uri-error message args))
(define (positive-exact-integer? port)
(and (number? port) (exact? port) (integer? port) (positive? port)))
(define (validate-uri scheme userinfo host port path query fragment)
(cond
((not (symbol? scheme))
(uri-error "Expected a symbol for the URI scheme: ~s" scheme))
((and (or userinfo port) (not host))
(uri-error "Expected a host, given userinfo or port"))
((and port (not (positive-exact-integer? port)))
(uri-error "Expected port to be an integer: ~s" port))
((and host (or (not (string? host)) (not (valid-host? host))))
(uri-error "Expected valid host: ~s" host))
((and userinfo (not (string? userinfo)))
(uri-error "Expected string for userinfo: ~s" userinfo))
((not (string? path))
(uri-error "Expected string for path: ~s" path))
((and host (not (string-null? path))
(not (eqv? (string-ref path 0) #\/)))
(uri-error "Expected path of absolute URI to start with a /: ~a" path))))
(define* (build-uri scheme #:key userinfo host port (path "") query fragment
(validate? #t))
"Construct a URI object. SCHEME should be a symbol, PORT
either a positive, exact integer or ‘#f’, and the rest of the
fields are either strings or ‘#f’. If VALIDATE? is true,
also run some consistency checks to make sure that the constructed URI
is valid."
(if validate?
(validate-uri scheme userinfo host port path query fragment))
(make-uri scheme userinfo host port path query fragment))
;; See RFC 3986 #3.2.2 for comments on percent-encodings, IDNA (RFC
;; 3490), and non-ASCII host names.
;;
(define ipv4-regexp
(make-regexp "^([0-9.]+)$"))
(define ipv6-regexp
(make-regexp "^([0-9a-fA-F:.]+)$"))
(define domain-label-regexp
(make-regexp "^[a-zA-Z0-9]([a-zA-Z0-9-]*[a-zA-Z0-9])?$"))
(define top-label-regexp
(make-regexp "^[a-zA-Z]([a-zA-Z0-9-]*[a-zA-Z0-9])?$"))
(define (valid-host? host)
(cond
((regexp-exec ipv4-regexp host)
(false-if-exception (inet-pton AF_INET host)))
((regexp-exec ipv6-regexp host)
(false-if-exception (inet-pton AF_INET6 host)))
(else
(let lp ((start 0))
(let ((end (string-index host #\. start)))
(if end
(and (regexp-exec domain-label-regexp
(substring host start end))
(lp (1+ end)))
(regexp-exec top-label-regexp host start)))))))
(define userinfo-pat
"[a-zA-Z0-9_.!~*'();:&=+$,-]+")
(define host-pat
"[a-zA-Z0-9.-]+")
(define ipv6-host-pat
"[0-9a-fA-F:.]+")
(define port-pat
"[0-9]*")
(define authority-regexp
(make-regexp
(format #f "^//((~a)@)?((~a)|(\\[(~a)\\]))(:(~a))?$"
userinfo-pat host-pat ipv6-host-pat port-pat)))
(define (parse-authority authority fail)
(if (equal? authority "//")
;; Allow empty authorities: file:///etc/hosts is a synonym of
;; file:/etc/hosts.
(values #f #f #f)
(let ((m (regexp-exec authority-regexp authority)))
(if (and m (valid-host? (or (match:substring m 4)
(match:substring m 6))))
(values (match:substring m 2)
(or (match:substring m 4)
(match:substring m 6))
(let ((port (match:substring m 8)))
(and port (not (string-null? port))
(string->number port))))
(fail)))))
;;; RFC 3986, #3.
;;;
;;; URI = scheme ":" hier-part [ "?" query ] [ "#" fragment ]
;;;
;;; hier-part = "//" authority path-abempty
;;; / path-absolute
;;; / path-rootless
;;; / path-empty
(define scheme-pat
"[a-zA-Z][a-zA-Z0-9+.-]*")
(define authority-pat
"[^/?#]*")
(define path-pat
"[^?#]*")
(define query-pat
"[^#]*")
(define fragment-pat
".*")
(define uri-pat
(format #f "^((~a):)?(//~a)?(~a)(\\?(~a))?(#(~a))?$"
scheme-pat authority-pat path-pat query-pat fragment-pat))
(define uri-regexp
(make-regexp uri-pat))
(define (string->uri* string)
"Parse STRING into a URI object. Return ‘#f’ if the string
could not be parsed."
(% (let ((m (regexp-exec uri-regexp string)))
(if (not m) (abort))
(let ((scheme (let ((str (match:substring m 2)))
(and str (string->symbol (string-downcase str)))))
(authority (match:substring m 3))
(path (match:substring m 4))
(query (match:substring m 6))
(fragment (match:substring m 7)))
(call-with-values
(lambda ()
(if authority
(parse-authority authority abort)
(values #f #f #f)))
(lambda (userinfo host port)
(make-uri scheme userinfo host port path query fragment)))))
(lambda (k)
#f)))
(define (string->uri string)
"Parse STRING into a URI object. Return ‘#f’ if the string
could not be parsed."
(let ((uri (string->uri* string)))
(and uri (uri-scheme uri) uri)))
(define *default-ports* (make-hash-table))
(define (declare-default-port! scheme port)
"Declare a default port for the given URI scheme."
(hashq-set! *default-ports* scheme port))
(define (default-port? scheme port)
(or (not port)
(eqv? port (hashq-ref *default-ports* scheme))))
(declare-default-port! 'http 80)
(declare-default-port! 'https 443)
(define (uri->string uri)
"Serialize URI to a string. If the URI has a port that is the
default port for its scheme, the port is not included in the
serialization."
(let* ((scheme (uri-scheme uri))
(userinfo (uri-userinfo uri))
(host (uri-host uri))
(port (uri-port uri))
(path (uri-path uri))
(query (uri-query uri))
(fragment (uri-fragment uri)))
(string-append
(if scheme
(string-append (symbol->string scheme) ":")
"")
(if host
(string-append "//"
(if userinfo (string-append userinfo "@")
"")
(if (string-index host #\:)
(string-append "[" host "]")
host)
(if (default-port? (uri-scheme uri) port)
""
(string-append ":" (number->string port))))
"")
path
(if query
(string-append "?" query)
"")
(if fragment
(string-append "#" fragment)
""))))
;; like call-with-output-string, but actually closes the port (doh)
(define (call-with-output-string* proc)
(let ((port (open-output-string)))
(proc port)
(let ((str (get-output-string port)))
(close-port port)
str)))
(define (call-with-output-bytevector* proc)
(call-with-values
(lambda ()
(open-bytevector-output-port))
(lambda (port get-bytevector)
(proc port)
(let ((bv (get-bytevector)))
(close-port port)
bv))))
(define (call-with-encoded-output-string encoding proc)
(if (string-ci=? encoding "utf-8")
(string->utf8 (call-with-output-string* proc))
(call-with-output-bytevector*
(lambda (port)
(set-port-encoding! port encoding)
(proc port)))))
(define (encode-string str encoding)
(if (string-ci=? encoding "utf-8")
(string->utf8 str)
(call-with-encoded-output-string encoding
(lambda (port)
(display str port)))))
(define (decode-string bv encoding)
(if (string-ci=? encoding "utf-8")
(utf8->string bv)
(let ((p (open-bytevector-input-port bv)))
(set-port-encoding! p encoding)
(let ((res (read-string p)))
(close-port p)
res))))
;; A note on characters and bytes: URIs are defined to be sequences of
;; characters in a subset of ASCII. Those characters may encode a
;; sequence of bytes (octets), which in turn may encode sequences of
;; characters in other character sets.
;;
;; Return a new string made from uri-decoding STR. Specifically,
;; turn ‘+’ into space, and hex-encoded ‘%XX’ strings into
;; their eight-bit characters.
;;
(define hex-chars
(string->char-set "0123456789abcdefABCDEF"))
(define* (uri-decode str #:key (encoding "utf-8") (decode-plus-to-space? #t))
"Percent-decode the given STR, according to ENCODING,
which should be the name of a character encoding.
Note that this function should not generally be applied to a full URI
string. For paths, use ‘split-and-decode-uri-path’ instead. For query
strings, split the query on ‘&’ and ‘=’ boundaries, and decode
the components separately.
Note also that percent-encoded strings encode _bytes_, not characters.
There is no guarantee that a given byte sequence is a valid string
encoding. Therefore this routine may signal an error if the decoded
bytes are not valid for the given encoding. Pass ‘#f’ for ENCODING if
you want decoded bytes as a bytevector directly. ‘set-port-encoding!’,
for more information on character encodings.
If DECODE-PLUS-TO-SPACE? is true, which is the default, also replace
instances of the plus character (+) with a space character. This is
needed when parsing application/x-www-form-urlencoded data.
Returns a string of the decoded characters, or a bytevector if
ENCODING was ‘#f’."
(let* ((len (string-length str))
(bv
(call-with-output-bytevector*
(lambda (port)
(let lp ((i 0))
(if (< i len)
(let ((ch (string-ref str i)))
(cond
((and (eqv? ch #\+) decode-plus-to-space?)
(put-u8 port (char->integer #\space))
(lp (1+ i)))
((and (< (+ i 2) len) (eqv? ch #\%)
(let ((a (string-ref str (+ i 1)))
(b (string-ref str (+ i 2))))
(and (char-set-contains? hex-chars a)
(char-set-contains? hex-chars b)
(string->number (string a b) 16))))
=> (lambda (u8)
(put-u8 port u8)
(lp (+ i 3))))
((< (char->integer ch) 128)
(put-u8 port (char->integer ch))
(lp (1+ i)))
(else
(uri-error "Invalid character in encoded URI ~a: ~s"
str ch))))))))))
(if encoding
(decode-string bv encoding)
;; Otherwise return raw bytevector
bv)))
(define ascii-alnum-chars
(string->char-set
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"))
;; RFC 3986, #2.2.
(define gen-delims
(string->char-set ":/?#[]@"))
(define sub-delims
(string->char-set "!$&'()*+,l="))
(define reserved-chars
(char-set-union gen-delims sub-delims))
;; RFC 3986, #2.3
(define unreserved-chars
(char-set-union ascii-alnum-chars
(string->char-set "-._~")))
;; Return a new string made from uri-encoding STR, unconditionally
;; transforming any characters not in UNESCAPED-CHARS.
;;
(define* (uri-encode str #:key (encoding "utf-8")
(unescaped-chars unreserved-chars))
"Percent-encode any character not in the character set,
UNESCAPED-CHARS.
The default character set includes alphanumerics from ASCII, as well as
the special characters ‘-’, ‘.’, ‘_’, and ‘~’. Any other character will
be percent-encoded, by writing out the character to a bytevector within
the given ENCODING, then encoding each byte as ‘%HH’, where HH is the
uppercase hexadecimal representation of the byte."
(define (needs-escaped? ch)
(not (char-set-contains? unescaped-chars ch)))
(if (string-index str needs-escaped?)
(call-with-output-string*
(lambda (port)
(string-for-each
(lambda (ch)
(if (char-set-contains? unescaped-chars ch)
(display ch port)
(let* ((bv (encode-string (string ch) encoding))
(len (bytevector-length bv)))
(let lp ((i 0))
(if (< i len)
(let ((byte (bytevector-u8-ref bv i)))
(display #\% port)
(when (< byte 16)
(display #\0 port))
(display (string-upcase (number->string byte 16))
port)
(lp (1+ i))))))))
str)))
str))
(define (split-and-decode-uri-path path)
"Split PATH into its components, and decode each component,
removing empty components.
For example, ‘\"/foo/bar%20baz/\"’ decodes to the two-element list,
‘(\"foo\" \"bar baz\")’."
(filter (lambda (x) (not (string-null? x)))
(map (lambda (s) (uri-decode s #:decode-plus-to-space? #f))
(string-split path #\/))))
(define (encode-and-join-uri-path parts)
"URI-encode each element of PARTS, which should be a list of
strings, and join the parts together with ‘/’ as a delimiter.
For example, the list ‘(\"scrambled eggs\" \"biscuits&gravy\")’
encodes as ‘\"scrambled%20eggs/biscuits%26gravy\"’."
(string-join (map uri-encode parts) "/"))
|