001 /* URLStreamHandler.java -- Abstract superclass for all protocol handlers
002 Copyright (C) 1998, 1999, 2002, 2003, 2004 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package java.net;
039
040 import java.io.File;
041 import java.io.IOException;
042
043
044 /*
045 * Written using on-line Java Platform 1.2 API Specification, as well
046 * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
047 * Status: Believed complete and correct.
048 */
049
050 /**
051 * This class is the superclass of all URL protocol handlers. The URL
052 * class loads the appropriate protocol handler to establish a connection
053 * to a (possibly) remote service (eg, "http", "ftp") and to do protocol
054 * specific parsing of URL's. Refer to the URL class documentation for
055 * details on how that class locates and loads protocol handlers.
056 * <p>
057 * A protocol handler implementation should override the openConnection()
058 * method, and optionally override the parseURL() and toExternalForm()
059 * methods if necessary. (The default implementations will parse/write all
060 * URL's in the same form as http URL's). A protocol specific subclass
061 * of URLConnection will most likely need to be created as well.
062 * <p>
063 * Note that the instance methods in this class are called as if they
064 * were static methods. That is, a URL object to act on is passed with
065 * every call rather than the caller assuming the URL is stored in an
066 * instance variable of the "this" object.
067 * <p>
068 * The methods in this class are protected and accessible only to subclasses.
069 * URLStreamConnection objects are intended for use by the URL class only,
070 * not by other classes (unless those classes are implementing protocols).
071 *
072 * @author Aaron M. Renn (arenn@urbanophile.com)
073 * @author Warren Levy (warrenl@cygnus.com)
074 *
075 * @see URL
076 */
077 public abstract class URLStreamHandler
078 {
079 /**
080 * Creates a URLStreamHander
081 */
082 public URLStreamHandler()
083 {
084 }
085
086 /**
087 * Returns a URLConnection for the passed in URL. Note that this should
088 * not actually create the connection to the (possibly) remote host, but
089 * rather simply return a URLConnection object. The connect() method of
090 * URL connection is used to establish the actual connection, possibly
091 * after the caller sets up various connection options.
092 *
093 * @param url The URL to get a connection object for
094 *
095 * @return A URLConnection object for the given URL
096 *
097 * @exception IOException If an error occurs
098 */
099 protected abstract URLConnection openConnection(URL url)
100 throws IOException;
101
102 /**
103 * This method parses the string passed in as a URL and set's the
104 * instance data fields in the URL object passed in to the various values
105 * parsed out of the string. The start parameter is the position to start
106 * scanning the string. This is usually the position after the ":" which
107 * terminates the protocol name. The end parameter is the position to
108 * stop scanning. This will be either the end of the String, or the
109 * position of the "#" character, which separates the "file" portion of
110 * the URL from the "anchor" portion.
111 * <p>
112 * This method assumes URL's are formatted like http protocol URL's, so
113 * subclasses that implement protocols with URL's the follow a different
114 * syntax should override this method. The lone exception is that if
115 * the protocol name set in the URL is "file", this method will accept
116 * an empty hostname (i.e., "file:///"), which is legal for that protocol
117 *
118 * @param url The URL object in which to store the results
119 * @param spec The String-ized URL to parse
120 * @param start The position in the string to start scanning from
121 * @param end The position in the string to stop scanning
122 */
123 protected void parseURL(URL url, String spec, int start, int end)
124 {
125 String host = url.getHost();
126 int port = url.getPort();
127 String file = url.getFile();
128 String ref = url.getRef();
129 String userInfo = url.getUserInfo();
130 String authority = url.getAuthority();
131 String query = null;
132
133 // On Windows we need to change \ to / for file URLs
134 char separator = File.separatorChar;
135 if (url.getProtocol().equals("file") && separator != '/')
136 {
137 file = file.replace(separator, '/');
138 spec = spec.replace(separator, '/');
139 }
140
141 if (spec.regionMatches(start, "//", 0, 2))
142 {
143 String genuineHost;
144 int hostEnd;
145 int colon;
146 int at_host;
147
148 start += 2;
149 int slash = spec.indexOf('/', start);
150 if (slash >= 0)
151 hostEnd = slash;
152 else
153 hostEnd = end;
154
155 authority = host = spec.substring(start, hostEnd);
156
157 // We first need a genuine host name (with userinfo).
158 // So we check for '@': if it's present check the port in the
159 // section after '@' in the other case check it in the full string.
160 // P.S.: We don't care having '@' at the beginning of the string.
161 if ((at_host = host.indexOf('@')) >= 0)
162 {
163 genuineHost = host.substring(at_host);
164 userInfo = host.substring(0, at_host);
165 }
166 else
167 genuineHost = host;
168
169 // Look for optional port number. It is valid for the non-port
170 // part of the host name to be null (e.g. a URL "http://:80").
171 // TBD: JDK 1.2 in this case sets host to null rather than "";
172 // this is undocumented and likely an unintended side effect in 1.2
173 // so we'll be simple here and stick with "". Note that
174 // "http://" or "http:///" produce a "" host in JDK 1.2.
175 if ((colon = genuineHost.indexOf(':')) >= 0)
176 {
177 try
178 {
179 port = Integer.parseInt(genuineHost.substring(colon + 1));
180 }
181 catch (NumberFormatException e)
182 {
183 // Ignore invalid port values; port is already set to u's
184 // port.
185 }
186
187 // Now we must cut the port number in the original string.
188 if (at_host >= 0)
189 host = host.substring(0, at_host + colon);
190 else
191 host = host.substring(0, colon);
192 }
193 file = null;
194 start = hostEnd;
195 }
196 else if (host == null)
197 host = "";
198
199 if (file == null || file.length() == 0
200 || (start < end && spec.charAt(start) == '/'))
201 {
202 // No file context available; just spec for file.
203 // Or this is an absolute path name; ignore any file context.
204 file = spec.substring(start, end);
205 ref = null;
206 }
207 else if (start < end)
208 {
209 // Context is available, but only override it if there is a new file.
210 int lastSlash = file.lastIndexOf('/');
211 if (lastSlash < 0)
212 file = spec.substring(start, end);
213 else
214 file = (file.substring(0, lastSlash)
215 + '/' + spec.substring(start, end));
216
217 // For URLs constructed relative to a context, we
218 // need to canonicalise the file path.
219 file = canonicalizeFilename(file);
220
221 ref = null;
222 }
223
224 if (ref == null)
225 {
226 // Normally there should be no '#' in the file part,
227 // but we are nice.
228 int hash = file.indexOf('#');
229 if (hash != -1)
230 {
231 ref = file.substring(hash + 1, file.length());
232 file = file.substring(0, hash);
233 }
234 }
235
236 // We care about the query tag only if there is no reference at all.
237 if (ref == null)
238 {
239 int queryTag = file.indexOf('?');
240 if (queryTag != -1)
241 {
242 query = file.substring(queryTag + 1);
243 file = file.substring(0, queryTag);
244 }
245 }
246
247 // XXX - Classpath used to call PlatformHelper.toCanonicalForm() on
248 // the file part. It seems like overhead, but supposedly there is some
249 // benefit in windows based systems (it also lowercased the string).
250 setURL(url, url.getProtocol(), host, port, authority, userInfo, file, query, ref);
251 }
252
253 /*
254 * Canonicalize a filename.
255 */
256 private static String canonicalizeFilename(String file)
257 {
258 // XXX - GNU Classpath has an implementation that might be more appropriate
259 // for Windows based systems (gnu.java.io.PlatformHelper.toCanonicalForm)
260 int index;
261
262 // Replace "/./" with "/". This probably isn't very efficient in
263 // the general case, but it's probably not bad most of the time.
264 while ((index = file.indexOf("/./")) >= 0)
265 file = file.substring(0, index) + file.substring(index + 2);
266
267 // Process "/../" correctly. This probably isn't very efficient in
268 // the general case, but it's probably not bad most of the time.
269 while ((index = file.indexOf("/../")) >= 0)
270 {
271 // Strip of the previous directory - if it exists.
272 int previous = file.lastIndexOf('/', index - 1);
273 if (previous >= 0)
274 file = file.substring(0, previous) + file.substring(index + 3);
275 else
276 break;
277 }
278 return file;
279 }
280
281 /**
282 * Compares two URLs, excluding the fragment component
283 *
284 * @param url1 The first url
285 * @param url2 The second url to compare with the first
286 *
287 * @return True if both URLs point to the same file, false otherwise.
288 *
289 * @specnote Now protected
290 */
291 protected boolean sameFile(URL url1, URL url2)
292 {
293 if (url1 == url2)
294 return true;
295
296 // This comparison is very conservative. It assumes that any
297 // field can be null.
298 if (url1 == null || url2 == null)
299 return false;
300 int p1 = url1.getPort();
301 if (p1 == -1)
302 p1 = url1.ph.getDefaultPort();
303 int p2 = url2.getPort();
304 if (p2 == -1)
305 p2 = url2.ph.getDefaultPort();
306 if (p1 != p2)
307 return false;
308 String s1;
309 String s2;
310 s1 = url1.getProtocol();
311 s2 = url2.getProtocol();
312 if (s1 != s2 && (s1 == null || ! s1.equals(s2)))
313 return false;
314 s1 = url1.getHost();
315 s2 = url2.getHost();
316 if (s1 != s2 && (s1 == null || ! s1.equals(s2)))
317 return false;
318 s1 = canonicalizeFilename(url1.getFile());
319 s2 = canonicalizeFilename(url2.getFile());
320 if (s1 != s2 && (s1 == null || ! s1.equals(s2)))
321 return false;
322 return true;
323 }
324
325 /**
326 * This methods sets the instance variables representing the various fields
327 * of the URL to the values passed in.
328 *
329 * @param u The URL to modify
330 * @param protocol The protocol to set
331 * @param host The host name to et
332 * @param port The port number to set
333 * @param file The filename to set
334 * @param ref The reference
335 *
336 * @exception SecurityException If the protocol handler of the URL is
337 * different from this one
338 *
339 * @deprecated 1.2 Please use
340 * #setURL(URL,String,String,int,String,String,String,String);
341 */
342 protected void setURL(URL u, String protocol, String host, int port,
343 String file, String ref)
344 {
345 u.set(protocol, host, port, file, ref);
346 }
347
348 /**
349 * Sets the fields of the URL argument to the indicated values
350 *
351 * @param u The URL to modify
352 * @param protocol The protocol to set
353 * @param host The host name to set
354 * @param port The port number to set
355 * @param authority The authority to set
356 * @param userInfo The user information to set
357 * @param path The path/filename to set
358 * @param query The query part to set
359 * @param ref The reference
360 *
361 * @exception SecurityException If the protocol handler of the URL is
362 * different from this one
363 */
364 protected void setURL(URL u, String protocol, String host, int port,
365 String authority, String userInfo, String path,
366 String query, String ref)
367 {
368 u.set(protocol, host, port, authority, userInfo, path, query, ref);
369 }
370
371 /**
372 * This is the default method for computing whether two URLs are
373 * equivalent. This method assumes that neither URL is null.
374 *
375 * @param url1 An URL object
376 * @param url2 Another URL object
377 *
378 * @return True if both given URLs are equal, false otherwise.
379 */
380 protected boolean equals(URL url1, URL url2)
381 {
382 // This comparison is very conservative. It assumes that any
383 // field can be null.
384 int port1 = url1.getPort();
385 if (port1 == -1)
386 port1 = url1.getDefaultPort();
387 int port2 = url2.getPort();
388 if (port2 == -1)
389 port2 = url2.getDefaultPort();
390 // Note that we don't bother checking the 'authority'; it is
391 // redundant.
392 return (port1 == port2
393 && ((url1.getProtocol() == null && url2.getProtocol() == null)
394 || (url1.getProtocol() != null
395 && url1.getProtocol().equals(url2.getProtocol())))
396 && ((url1.getUserInfo() == null && url2.getUserInfo() == null)
397 || (url1.getUserInfo() != null
398 && url1.getUserInfo().equals(url2.getUserInfo())))
399 && ((url1.getHost() == null && url2.getHost() == null)
400 || (url1.getHost() != null && url1.getHost().equals(url2.getHost())))
401 && ((url1.getPath() == null && url2.getPath() == null)
402 || (url1.getPath() != null && url1.getPath().equals(url2.getPath())))
403 && ((url1.getQuery() == null && url2.getQuery() == null)
404 || (url1.getQuery() != null
405 && url1.getQuery().equals(url2.getQuery())))
406 && ((url1.getRef() == null && url2.getRef() == null)
407 || (url1.getRef() != null && url1.getRef().equals(url2.getRef()))));
408 }
409
410 /**
411 * Compares the host components of two URLs.
412 *
413 * @param url1 The first URL.
414 * @param url2 The second URL.
415 *
416 * @return True if both URLs contain the same host.
417 */
418 protected boolean hostsEqual(URL url1, URL url2)
419 {
420 InetAddress addr1 = getHostAddress(url1);
421 InetAddress addr2 = getHostAddress(url2);
422
423 if (addr1 != null && addr2 != null)
424 return addr1.equals(addr2);
425
426 String host1 = url1.getHost();
427 String host2 = url2.getHost();
428
429 if (host1 != null && host2 != null)
430 return host1.equalsIgnoreCase(host2);
431
432 return host1 == null && host2 == null;
433 }
434
435 /**
436 * Get the IP address of our host. An empty host field or a DNS failure will
437 * result in a null return.
438 *
439 * @param url The URL to return the host address for.
440 *
441 * @return The address of the hostname in url.
442 */
443 protected InetAddress getHostAddress(URL url)
444 {
445 String hostname = url.getHost();
446
447 if (hostname.equals(""))
448 return null;
449
450 try
451 {
452 return InetAddress.getByName(hostname);
453 }
454 catch (UnknownHostException e)
455 {
456 return null;
457 }
458 }
459
460 /**
461 * Returns the default port for a URL parsed by this handler. This method is
462 * meant to be overidden by handlers with default port numbers.
463 *
464 * @return The default port number.
465 */
466 protected int getDefaultPort()
467 {
468 return -1;
469 }
470
471 /**
472 * Provides the default hash calculation. May be overidden by handlers for
473 * other protocols that have different requirements for hashCode calculation.
474 *
475 * @param url The URL to calc the hashcode for.
476 *
477 * @return The hashcode for the given URL.
478 */
479 protected int hashCode(URL url)
480 {
481 return url.getProtocol().hashCode()
482 + ((url.getHost() == null) ? 0 : url.getHost().hashCode())
483 + url.getFile().hashCode() + url.getPort();
484 }
485
486 /**
487 * This method converts a URL object into a String. This method creates
488 * Strings in the mold of http URL's, so protocol handlers which use URL's
489 * that have a different syntax should override this method
490 *
491 * @param url The URL object to convert
492 *
493 * @return A string representation of the url
494 */
495 protected String toExternalForm(URL url)
496 {
497 String protocol;
498 String file;
499 String ref;
500 String authority;
501
502 protocol = url.getProtocol();
503 authority = url.getAuthority();
504 if (authority == null)
505 authority = "";
506
507 file = url.getFile();
508 ref = url.getRef();
509
510 // Guess a reasonable size for the string buffer so we have to resize
511 // at most once.
512 int size = protocol.length() + authority.length() + file.length() + 24;
513 StringBuffer sb = new StringBuffer(size);
514
515 if (protocol.length() > 0)
516 {
517 sb.append(protocol);
518 sb.append(":");
519 }
520
521 // If we have superfluous leading slashes (that means, at least 2)
522 // we always add the authority component ("//" + host) to
523 // avoid ambiguity. Otherwise we would generate an URL like
524 // proto://home/foo
525 // where we meant:
526 // host: <empty> - file: //home/foo
527 // but URL spec says it is:
528 // host: home - file: /foo
529 if (authority.length() != 0 || file.startsWith("//") )
530 sb.append("//").append(authority).append(file);
531 else
532 sb.append(file);
533
534 if (ref != null)
535 sb.append('#').append(ref);
536
537 return sb.toString();
538 }
539 }