1URI(3) User Contributed Perl Documentation URI(3)
2
6 URI - Uniform Resource Identifiers (absolute and relative)
7
9 $u1 = URI->new("http://www.perl.com");
10 $u2 = URI->new("foo", "http");
11 $u3 = $u2->abs($u1);
12 $u4 = $u3->clone;
13 $u5 = URI->new("HTTP://WWW.perl.com:80")->canonical;
14 $str = $u->as_string;
16 $str = "$u";
17 $scheme = $u->scheme;
19 $opaque = $u->opaque;
20 $path = $u->path;
21 $frag = $u->fragment;
22 $u->scheme("ftp");
24 $u->host("ftp.perl.com");
25 $u->path("cpan/");
26
28 This module implements the "URI" class. Objects of this class repre‐
29 sent "Uniform Resource Identifier references" as specified in RFC 2396
30 (and updated by RFC 2732).
31 A Uniform Resource Identifier is a compact string of characters that
33 identifies an abstract or physical resource. A Uniform Resource Iden‐
34 tifier can be further classified as either a Uniform Resource Locator
35 (URL) or a Uniform Resource Name (URN). The distinction between URL
36 and URN does not matter to the "URI" class interface. A "URI-reference"
37 is a URI that may have additional information attached in the form of a
38 fragment identifier.
39 An absolute URI reference consists of three parts: a scheme, a scheme-
41 specific part and a fragment identifier. A subset of URI references
42 share a common syntax for hierarchical namespaces. For these, the
43 scheme-specific part is further broken down into authority, path and
44 query components. These URIs can also take the form of relative URI
45 references, where the scheme (and usually also the authority) component
46 is missing, but implied by the context of the URI reference. The three
47 forms of URI reference syntax are summarized as follows:
48 <scheme>:<scheme-specific-part>#<fragment>
50 <scheme>://<authority><path>?<query>#<fragment>
51 <path>?<query>#<fragment>
52 The components into which a URI reference can be divided depend on the
54 scheme. The "URI" class provides methods to get and set the individual
55 components. The methods available for a specific "URI" object depend
56 on the scheme.
57
59 The following methods construct new "URI" objects:
60 $uri = URI->new( $str )
62 $uri = URI->new( $str, $scheme )
63 Constructs a new URI object. The string representation of a URI is
64 given as argument, together with an optional scheme specification.
65 Common URI wrappers like "" and <>, as well as leading and trailing
66 white space, are automatically removed from the $str argument
67 before it is processed further.
68 The constructor determines the scheme, maps this to an appropriate
70 URI subclass, constructs a new object of that class and returns it.
71 The $scheme argument is only used when $str is a relative URI. It
73 can be either a simple string that denotes the scheme, a string
74 containing an absolute URI reference, or an absolute "URI" object.
75 If no $scheme is specified for a relative URI $str, then $str is
76 simply treated as a generic URI (no scheme-specific methods avail‐
77 able).
78 The set of characters available for building URI references is
80 restricted (see URI::Escape). Characters outside this set are
81 automatically escaped by the URI constructor.
82 $uri = URI->new_abs( $str, $base_uri )
84 Constructs a new absolute URI object. The $str argument can denote
85 a relative or absolute URI. If relative, then it is absolutized
86 using $base_uri as base. The $base_uri must be an absolute URI.
87 $uri = URI::file->new( $filename )
89 $uri = URI::file->new( $filename, $os )
90 Constructs a new file URI from a file name. See URI::file.
91 $uri = URI::file->new_abs( $filename )
93 $uri = URI::file->new_abs( $filename, $os )
94 Constructs a new absolute file URI from a file name. See
95 URI::file.
96 $uri = URI::file->cwd
98 Returns the current working directory as a file URI. See
99 URI::file.
100 $uri->clone
102 Returns a copy of the $uri.
103
105 The methods described in this section are available for all "URI"
106 objects.
107 Methods that give access to components of a URI always return the old
109 value of the component. The value returned is "undef" if the component
110 was not present. There is generally a difference between a component
111 that is empty (represented as "") and a component that is missing (rep‐
112 resented as "undef"). If an accessor method is given an argument, it
113 updates the corresponding component in addition to returning the old
114 value of the component. Passing an undefined argument removes the com‐
115 ponent (if possible). The description of each accessor method indi‐
116 cates whether the component is passed as an escaped or an unescaped
117 string. A component that can be further divided into sub-parts are
118 usually passed escaped, as unescaping might change its semantics.
119 The common methods available for all URI are:
121 $uri->scheme
123 $uri->scheme( $new_scheme )
124 Sets and returns the scheme part of the $uri. If the $uri is rela‐
125 tive, then $uri->scheme returns "undef". If called with an argu‐
126 ment, it updates the scheme of $uri, possibly changing the class of
127 $uri, and returns the old scheme value. The method croaks if the
128 new scheme name is illegal; a scheme name must begin with a letter
129 and must consist of only US-ASCII letters, numbers, and a few spe‐
130 cial marks: ".", "+", "-". This restriction effectively means that
131 the scheme must be passed unescaped. Passing an undefined argument
132 to the scheme method makes the URI relative (if possible).
133 Letter case does not matter for scheme names. The string returned
135 by $uri->scheme is always lowercase. If you want the scheme just
136 as it was written in the URI in its original case, you can use the
137 $uri->_scheme method instead.
138 $uri->opaque
140 $uri->opaque( $new_opaque )
141 Sets and returns the scheme-specific part of the $uri (everything
142 between the scheme and the fragment) as an escaped string.
143 $uri->path
145 $uri->path( $new_path )
146 Sets and returns the same value as $uri->opaque unless the URI sup‐
147 ports the generic syntax for hierarchical namespaces. In that case
148 the generic method is overridden to set and return the part of the
149 URI between the host name and the fragment.
150 $uri->fragment
152 $uri->fragment( $new_frag )
153 Returns the fragment identifier of a URI reference as an escaped
154 string.
155 $uri->as_string
157 Returns a URI object to a plain string. URI objects are also con‐
158 verted to plain strings automatically by overloading. This means
159 that $uri objects can be used as plain strings in most Perl con‐
160 structs.
161 $uri->canonical
163 Returns a normalized version of the URI. The rules for normaliza‐
164 tion are scheme-dependent. They usually involve lowercasing the
165 scheme and Internet host name components, removing the explicit
166 port specification if it matches the default port, uppercasing all
167 escape sequences, and unescaping octets that can be better repre‐
168 sented as plain characters.
169 For efficiency reasons, if the $uri is already in normalized form,
171 then a reference to it is returned instead of a copy.
172 $uri->eq( $other_uri )
174 URI::eq( $first_uri, $other_uri )
175 Tests whether two URI references are equal. URI references that
176 normalize to the same string are considered equal. The method can
177 also be used as a plain function which can also test two string
178 arguments.
179 If you need to test whether two "URI" object references denote the
181 same object, use the '==' operator.
182 $uri->abs( $base_uri )
184 Returns an absolute URI reference. If $uri is already absolute,
185 then a reference to it is simply returned. If the $uri is rela‐
186 tive, then a new absolute URI is constructed by combining the $uri
187 and the $base_uri, and returned.
188 $uri->rel( $base_uri )
190 Returns a relative URI reference if it is possible to make one that
191 denotes the same resource relative to $base_uri. If not, then $uri
192 is simply returned.
193
195 The following methods are available to schemes that use the com‐
196 mon/generic syntax for hierarchical namespaces. The descriptions of
197 schemes below indicate which these are. Unknown schemes are assumed to
198 support the generic syntax, and therefore the following methods:
199 $uri->authority
201 $uri->authority( $new_authority )
202 Sets and returns the escaped authority component of the $uri.
203 $uri->path
205 $uri->path( $new_path )
206 Sets and returns the escaped path component of the $uri (the part
207 between the host name and the query or fragment). The path can
208 never be undefined, but it can be the empty string.
209 $uri->path_query
211 $uri->path_query( $new_path_query )
212 Sets and returns the escaped path and query components as a single
213 entity. The path and the query are separated by a "?" character,
214 but the query can itself contain "?".
215 $uri->path_segments
217 $uri->path_segments( $segment, ... )
218 Sets and returns the path. In a scalar context, it returns the
219 same value as $uri->path. In a list context, it returns the
220 unescaped path segments that make up the path. Path segments that
221 have parameters are returned as an anonymous array. The first ele‐
222 ment is the unescaped path segment proper; subsequent elements are
223 escaped parameter strings. Such an anonymous array uses overload‐
224 ing so it can be treated as a string too, but this string does not
225 include the parameters.
226 Note that absolute paths have the empty string as their first
228 path_segment, i.e. the path "/foo/bar" have 3 path_segments; "",
229 "foo" and "bar".
230 $uri->query
232 $uri->query( $new_query )
233 Sets and returns the escaped query component of the $uri.
234 $uri->query_form
236 $uri->query_form( $key1 => $val1, $key2 => $val2, ... )
237 $uri->query_form( \@key_value_pairs )
238 $uri->query_form( \%hash )
239 Sets and returns query components that use the applica‐
240 tion/x-www-form-urlencoded format. Key/value pairs are separated
241 by "&", and the key is separated from the value by a "=" character.
242 The form can be set either by passing separate key/value pairs, or
244 via an array or hash reference. Passing an empty array or an empty
245 hash removes the query component, whereas passing no arguments at
246 all leaves the component unchanged. The order of keys is undefined
247 if a hash reference is passed. The old value is always returned as
248 a list of separate key/value pairs. Assigning this list to a hash
249 is unwise as the keys returned might repeat.
250 The values passed when setting the form can be plain strings or
252 references to arrays of strings. Passing an array of values has
253 the same effect as passing the key repeatedly with one value at a
254 time. All the following statements have the same effect:
255 $uri->query_form(foo => 1, foo => 2);
257 $uri->query_form(foo => [1, 2]);
258 $uri->query_form([ foo => 1, foo => 2 ]);
259 $uri->query_form([ foo => [1, 2] ]);
260 $uri->query_form({ foo => [1, 2] });
261 The "URI::QueryParam" module can be loaded to add further methods
263 to manipulate the form of a URI. See URI::QueryParam for details.
264 $uri->query_keywords
266 $uri->query_keywords( $keywords, ... )
267 $uri->query_keywords( \@keywords )
268 Sets and returns query components that use the keywords separated
269 by "+" format.
270 The keywords can be set either by passing separate keywords
272 directly or by passing a reference to an array of keywords. Pass‐
273 ing an empty array removes the query component, whereas passing no
274 arguments at all leaves the component unchanged. The old value is
275 always returned as a list of separate words.
276
278 For schemes where the authority component denotes an Internet host, the
279 following methods are available in addition to the generic methods.
280 $uri->userinfo
282 $uri->userinfo( $new_userinfo )
283 Sets and returns the escaped userinfo part of the authority compo‐
284 nent.
285 For some schemes this is a user name and a password separated by a
287 colon. This practice is not recommended. Embedding passwords in
288 clear text (such as URI) has proven to be a security risk in almost
289 every case where it has been used.
290 $uri->host
292 $uri->host( $new_host )
293 Sets and returns the unescaped hostname.
294 If the $new_host string ends with a colon and a number, then this
296 number also sets the port.
297 $uri->port
299 $uri->port( $new_port )
300 Sets and returns the port. The port is a simple integer that
301 should be greater than 0.
302 If a port is not specified explicitly in the URI, then the URI
304 scheme's default port is returned. If you don't want the default
305 port substituted, then you can use the $uri->_port method instead.
306 $uri->host_port
308 $uri->host_port( $new_host_port )
309 Sets and returns the host and port as a single unit. The returned
310 value includes a port, even if it matches the default port. The
311 host part and the port part are separated by a colon: ":".
312 $uri->default_port
314 Returns the default port of the URI scheme to which $uri belongs.
315 For http this is the number 80, for ftp this is the number 21, etc.
316 The default port for a scheme can not be changed.
317
319 Scheme-specific support is provided for the following URI schemes. For
320 "URI" objects that do not belong to one of these, you can only use the
321 common and generic methods.
322 data:
324 The data URI scheme is specified in RFC 2397. It allows inclusion
325 of small data items as "immediate" data, as if it had been included
326 externally.
327 "URI" objects belonging to the data scheme support the common meth‐
329 ods and two new methods to access their scheme-specific components:
330 $uri->media_type and $uri->data. See URI::data for details.
331 file:
333 An old specification of the file URI scheme is found in RFC 1738.
334 A new RFC 2396 based specification in not available yet, but file
335 URI references are in common use.
336 "URI" objects belonging to the file scheme support the common and
338 generic methods. In addition, they provide two methods for mapping
339 file URIs back to local file names; $uri->file and $uri->dir. See
340 URI::file for details.
341 ftp:
343 An old specification of the ftp URI scheme is found in RFC 1738. A
344 new RFC 2396 based specification in not available yet, but ftp URI
345 references are in common use.
346 "URI" objects belonging to the ftp scheme support the common,
348 generic and server methods. In addition, they provide two methods
349 for accessing the userinfo sub-components: $uri->user and
350 $uri->password.
351 gopher:
353 The gopher URI scheme is specified in
354 <draft-murali-url-gopher-1996-12-04> and will hopefully be avail‐
355 able as a RFC 2396 based specification.
356 "URI" objects belonging to the gopher scheme support the common,
358 generic and server methods. In addition, they support some methods
359 for accessing gopher-specific path components: $uri->gopher_type,
360 $uri->selector, $uri->search, $uri->string.
361 http:
363 The http URI scheme is specified in RFC 2616. The scheme is used
364 to reference resources hosted by HTTP servers.
365 "URI" objects belonging to the http scheme support the common,
367 generic and server methods.
368 https:
370 The https URI scheme is a Netscape invention which is commonly
371 implemented. The scheme is used to reference HTTP servers through
372 SSL connections. Its syntax is the same as http, but the default
373 port is different.
374 ldap:
376 The ldap URI scheme is specified in RFC 2255. LDAP is the Light‐
377 weight Directory Access Protocol. An ldap URI describes an LDAP
378 search operation to perform to retrieve information from an LDAP
379 directory.
380 "URI" objects belonging to the ldap scheme support the common,
382 generic and server methods as well as ldap-specific methods:
383 $uri->dn, $uri->attributes, $uri->scope, $uri->filter, $uri->exten‐
384 sions. See URI::ldap for details.
385 ldapi:
387 Like the ldap URI scheme, but uses a UNIX domain socket. The
388 server methods are not supported, and the local socket path is
389 available as $uri->un_path. The ldapi scheme is used by the OpenL‐
390 DAP package. There is no real specification for it, but it is men‐
391 tioned in various OpenLDAP manual pages.
392 ldaps:
394 Like the ldap URI scheme, but uses an SSL connection. This scheme
395 is deprecated, as the preferred way is to use the start_tls mecha‐
396 nism.
397 mailto:
399 The mailto URI scheme is specified in RFC 2368. The scheme was
400 originally used to designate the Internet mailing address of an
401 individual or service. It has (in RFC 2368) been extended to allow
402 setting of other mail header fields and the message body.
403 "URI" objects belonging to the mailto scheme support the common
405 methods and the generic query methods. In addition, they support
406 the following mailto-specific methods: $uri->to, $uri->headers.
407 mms:
409 The mms URL specification can be found at <http://sdp.ppona.com/>
410 "URI" objects belonging to the mms scheme support the common,
411 generic, and server methods, with the exception of userinfo and
412 query-related sub-components.
413 news:
415 The news, nntp and snews URI schemes are specified in
416 <draft-gilman-news-url-01> and will hopefully be available as an
417 RFC 2396 based specification soon.
418 "URI" objects belonging to the news scheme support the common,
420 generic and server methods. In addition, they provide some methods
421 to access the path: $uri->group and $uri->message.
422 nntp:
424 See news scheme.
425 pop:
427 The pop URI scheme is specified in RFC 2384. The scheme is used to
428 reference a POP3 mailbox.
429 "URI" objects belonging to the pop scheme support the common,
431 generic and server methods. In addition, they provide two methods
432 to access the userinfo components: $uri->user and $uri->auth
433 rlogin:
435 An old specification of the rlogin URI scheme is found in RFC 1738.
436 "URI" objects belonging to the rlogin scheme support the common,
437 generic and server methods.
438 rtsp:
440 The rtsp URL specification can be found in section 3.2 of RFC 2326.
441 "URI" objects belonging to the rtsp scheme support the common,
442 generic, and server methods, with the exception of userinfo and
443 query-related sub-components.
444 rtspu:
446 The rtspu URI scheme is used to talk to RTSP servers over UDP
447 instead of TCP. The syntax is the same as rtsp.
448 rsync:
450 Information about rsync is available from http://rsync.samba.org.
451 "URI" objects belonging to the rsync scheme support the common,
452 generic and server methods. In addition, they provide methods to
453 access the userinfo sub-components: $uri->user and $uri->password.
454 sip:
456 The sip URI specification is described in sections 19.1 and 25 of
457 RFC 3261. "URI" objects belonging to the sip scheme support the
458 common, generic, and server methods with the exception of path
459 related sub-components. In addition, they provide two methods to
460 get and set sip parameters: $uri->params_form and $uri->params.
461 sips:
463 See sip scheme. Its syntax is the same as sip, but the default
464 port is different.
465 snews:
467 See news scheme. Its syntax is the same as news, but the default
468 port is different.
469 telnet:
471 An old specification of the telnet URI scheme is found in RFC 1738.
472 "URI" objects belonging to the telnet scheme support the common,
473 generic and server methods.
474 tn3270:
476 These URIs are used like telnet URIs but for connections to IBM
477 mainframes. "URI" objects belonging to the tn3270 scheme support
478 the common, generic and server methods.
479 ssh:
481 Information about ssh is available at http://www.openssh.com/.
482 "URI" objects belonging to the ssh scheme support the common,
483 generic and server methods. In addition, they provide methods to
484 access the userinfo sub-components: $uri->user and $uri->password.
485 urn:
487 The syntax of Uniform Resource Names is specified in RFC 2141.
488 "URI" objects belonging to the urn scheme provide the common meth‐
489 ods, and also the methods $uri->nid and $uri->nss, which return the
490 Namespace Identifier and the Namespace-Specific String respec‐
491 tively.
492 The Namespace Identifier basically works like the Scheme identifier
494 of URIs, and further divides the URN namespace. Namespace Identi‐
495 fier assignments are maintained at <http://www.iana.org/assign‐
496 ments/urn-namespaces>.
497 Letter case is not significant for the Namespace Identifier. It is
499 always returned in lower case by the $uri->nid method. The
500 $uri->_nid method can be used if you want it in its original case.
501 urn:isbn:
503 The "urn:isbn:" namespace contains International Standard Book Num‐
504 bers (ISBNs) and is described in RFC 3187. A "URI" object belong‐
505 ing to this namespace has the following extra methods (if the Busi‐
506 ness::ISBN module is available): $uri->isbn, $uri->isbn_pub‐
507 lisher_code, $uri->isbn_country_code, $uri->isbn_as_ean.
508 urn:oid:
510 The "urn:oid:" namespace contains Object Identifiers (OIDs) and is
511 described in RFC 3061. An object identifier consists of sequences
512 of digits separated by dots. A "URI" object belonging to this
513 namespace has an additional method called $uri->oid that can be
514 used to get/set the oid value. In a list context, oid numbers are
515 returned as separate elements.
516
518 The following configuration variables influence how the class and its
519 methods behave:
520 $URI::ABS_ALLOW_RELATIVE_SCHEME
522 Some older parsers used to allow the scheme name to be present in
523 the relative URL if it was the same as the base URL scheme. RFC
524 2396 says that this should be avoided, but you can enable this old
525 behaviour by setting the $URI::ABS_ALLOW_RELATIVE_SCHEME variable
526 to a TRUE value. The difference is demonstrated by the following
527 examples:
528 URI->new("http:foo")->abs("http://host/a/b")
530 ==> "http:foo"
531 local $URI::ABS_ALLOW_RELATIVE_SCHEME = 1;
533 URI->new("http:foo")->abs("http://host/a/b")
534 ==> "http:/host/a/foo"
535 $URI::ABS_REMOTE_LEADING_DOTS
537 You can also have the abs() method ignore excess ".." segments in
538 the relative URI by setting $URI::ABS_REMOTE_LEADING_DOTS to a TRUE
539 value. The difference is demonstrated by the following examples:
540 URI->new("../../../foo")->abs("http://host/a/b")
542 ==> "http://host/../../foo"
543 local $URI::ABS_REMOTE_LEADING_DOTS = 1;
545 URI->new("../../../foo")->abs("http://host/a/b")
546 ==> "http://host/foo"
547
549 Using regexp variables like $1 directly as arguments to the URI methods
550 does not work too well with current perl implementations. I would
551 argue that this is actually a bug in perl. The workaround is to quote
552 them. Example:
553 /(...)/ ⎪⎪ die;
555 $u->query("$1");
556
558 As an alternative to this module, the following (official) regular
559 expression can be used to decode a URI:
560 my($scheme, $authority, $path, $query, $fragment) =
562 $uri =~ m⎪(?:([^:/?#]+):)?(?://([^/?#]*))?([^?#]*)(?:\?([^#]*))?(?:#(.*))?⎪;
563 The "URI::Split" module provides the function uri_split() as a readable
565 alternative.
566
568 URI::file, URI::WithBase, URI::QueryParam, URI::Escape, URI::Split,
569 URI::Heuristic
570 RFC 2396: "Uniform Resource Identifiers (URI): Generic Syntax", Bern‐
572 ers-Lee, Fielding, Masinter, August 1998.
573 http://www.iana.org/assignments/uri-schemes
575 http://www.iana.org/assignments/urn-namespaces
577 http://www.w3.org/Addressing/
579
581 Copyright 1995-2003 Gisle Aas.
582 Copyright 1995 Martijn Koster.
584 This program is free software; you can redistribute it and/or modify it
586 under the same terms as Perl itself.
587
589 This module is based on the "URI::URL" module, which in turn was (dis‐
590 tantly) based on the "wwwurl.pl" code in the libwww-perl for perl4
591 developed by Roy Fielding, as part of the Arcadia project at the Uni‐
592 versity of California, Irvine, with contributions from Brooks Cutter.
593 "URI::URL" was developed by Gisle Aas, Tim Bunce, Roy Fielding and Mar‐
595 tijn Koster with input from other people on the libwww-perl mailing
596 list.
597 "URI" and related subclasses was developed by Gisle Aas.
599perl v5.8.8 2004-01-14 URI(3)