aoqi@0: /*
aoqi@0:  * Copyright (c) 2009, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.  Oracle designates this
aoqi@0:  * particular file as subject to the "Classpath" exception as provided
aoqi@0:  * by Oracle in the LICENSE file that accompanied this code.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: package com.sun.xml.internal.dtdparser;
aoqi@0: 
aoqi@0: import org.xml.sax.EntityResolver;
aoqi@0: import org.xml.sax.InputSource;
aoqi@0: 
aoqi@0: import java.io.File;
aoqi@0: import java.io.FileInputStream;
aoqi@0: import java.io.IOException;
aoqi@0: import java.io.InputStream;
aoqi@0: import java.net.URL;
aoqi@0: import java.net.URLConnection;
aoqi@0: import java.util.Hashtable;
aoqi@0: 
aoqi@0: /**
aoqi@0:  * This entity resolver class provides a number of utilities which can help
aoqi@0:  * managment of external parsed entities in XML.  These are commonly used
aoqi@0:  * to hold markup declarations that are to be used as part of a Document
aoqi@0:  * Type Declaration (DTD), or to hold text marked up with XML.
aoqi@0:  * <p/>
aoqi@0:  * <P> Features include: <UL>
aoqi@0:  * <p/>
aoqi@0:  * <LI> Static factory methods are provided for constructing SAX InputSource
aoqi@0:  * objects from Files, URLs, or MIME objects.  This eliminates a class of
aoqi@0:  * error-prone coding in applications.
aoqi@0:  * <p/>
aoqi@0:  * <LI> Character encodings for XML documents are correctly supported: <UL>
aoqi@0:  * <p/>
aoqi@0:  * <LI> The encodings defined in the RFCs for MIME content types
aoqi@0:  * (2046 for general MIME, and 2376 for XML in particular), are
aoqi@0:  * supported, handling <em>charset=...</em> attributes and accepting
aoqi@0:  * content types which are known to be safe for use with XML;
aoqi@0:  * <p/>
aoqi@0:  * <LI> The character encoding autodetection algorithm identified
aoqi@0:  * in the XML specification is used, and leverages all of
aoqi@0:  * the JDK 1.1 (and later) character encoding support.
aoqi@0:  * <p/>
aoqi@0:  * <LI> The use of MIME typing may optionally be disabled, forcing the
aoqi@0:  * use of autodetection, to support web servers which don't correctly
aoqi@0:  * report MIME types for XML.  For example, they may report text that
aoqi@0:  * is encoded in EUC-JP as being US-ASCII text, leading to fatal
aoqi@0:  * errors during parsing.
aoqi@0:  * <p/>
aoqi@0:  * <LI> The InputSource objects returned by this class always
aoqi@0:  * have a <code>java.io.Reader</code> available as the "character
aoqi@0:  * stream" property.
aoqi@0:  * <p/>
aoqi@0:  * </UL>
aoqi@0:  * <p/>
aoqi@0:  * <LI> Catalog entries can map public identifiers to Java resources or
aoqi@0:  * to local URLs.  These are used to reduce network dependencies and loads,
aoqi@0:  * and will often be used for external DTD components.  For example, packages
aoqi@0:  * shipping DTD files as resources in JAR files can eliminate network traffic
aoqi@0:  * when accessing them, and sites may provide local caches of common DTDs.
aoqi@0:  * Note that no particular catalog syntax is supported by this class, only
aoqi@0:  * the notion of a set of entries.
aoqi@0:  * <p/>
aoqi@0:  * </UL>
aoqi@0:  * <p/>
aoqi@0:  * <P> Subclasses can perform tasks such as supporting new URI schemes for
aoqi@0:  * URIs which are not URLs, such as URNs (see RFC 2396) or for accessing
aoqi@0:  * MIME entities which are part of a <em>multipart/related</em> group
aoqi@0:  * (see RFC 2387).  They may also be used to support particular catalog
aoqi@0:  * syntaxes, such as the <a href="http://www.oasis-open.org/html/a401.htm">
aoqi@0:  * SGML/Open Catalog (SOCAT)</a> which supports the SGML notion of "Formal
aoqi@0:  * Public Identifiers (FPIs).
aoqi@0:  *
aoqi@0:  * @author David Brownell
aoqi@0:  * @author Janet Koenig
aoqi@0:  * @version 1.3 00/02/24
aoqi@0:  */
aoqi@0: public class Resolver implements EntityResolver {
aoqi@0:     private boolean ignoringMIME;
aoqi@0: 
aoqi@0:     // table mapping public IDs to (local) URIs
aoqi@0:     private Hashtable id2uri;
aoqi@0: 
aoqi@0:     // tables mapping public IDs to resources and classloaders
aoqi@0:     private Hashtable id2resource;
aoqi@0:     private Hashtable id2loader;
aoqi@0: 
aoqi@0:     //
aoqi@0:     // table of MIME content types (less attributes!) known
aoqi@0:     // to be mostly "OK" to use with XML MIME entities.  the
aoqi@0:     // idea is to rule out obvious braindamage ("image/jpg")
aoqi@0:     // not the subtle stuff ("text/html") that might actually
aoqi@0:     // be (or become) safe.
aoqi@0:     //
aoqi@0:     private static final String types [] = {
aoqi@0:         "application/xml",
aoqi@0:         "text/xml",
aoqi@0:         "text/plain",
aoqi@0:         "text/html", // commonly mis-inferred
aoqi@0:         "application/x-netcdf", // this is often illegal XML
aoqi@0:         "content/unknown"
aoqi@0:     };
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Constructs a resolver.
aoqi@0:      */
aoqi@0:     public Resolver() {
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Returns an input source, using the MIME type information and URL
aoqi@0:      * scheme to statically determine the correct character encoding if
aoqi@0:      * possible and otherwise autodetecting it.  MIME carefully specifies
aoqi@0:      * the character encoding defaults, and how attributes of the content
aoqi@0:      * type can change it.  XML further specifies two mandatory encodings
aoqi@0:      * (UTF-8 and UTF-16), and includes an XML declaration which can be
aoqi@0:      * used to internally label most documents encoded using US-ASCII
aoqi@0:      * supersets (such as Shift_JIS, EUC-JP, ISO-2022-*, ISO-8859-*, and
aoqi@0:      * more).
aoqi@0:      * <p/>
aoqi@0:      * <P> This method can be used to access XML documents which do not
aoqi@0:      * have URIs (such as servlet input streams, or most JavaMail message
aoqi@0:      * entities) and to support access methods such as HTTP POST or PUT.
aoqi@0:      * (URLs normally return content using the GET method.)
aoqi@0:      * <p/>
aoqi@0:      * <P> <em> The caller should set the system ID in order for relative URIs
aoqi@0:      * found in this document to be interpreted correctly.</em> In some cases,
aoqi@0:      * a custom resolver will need to be used; for example, documents
aoqi@0:      * may be grouped in a single MIME "multipart/related" bundle, and
aoqi@0:      * relative URLs would refer to other documents in that bundle.
aoqi@0:      *
aoqi@0:      * @param contentType The MIME content type for the source for which
aoqi@0:      *                    an InputSource is desired, such as <em>text/xml;charset=utf-8</em>.
aoqi@0:      * @param stream      The input byte stream for the input source.
aoqi@0:      * @param checkType   If true, this verifies that the content type is known
aoqi@0:      *                    to support XML documents, such as <em>application/xml</em>.
aoqi@0:      * @param scheme      Unless this is "file", unspecified MIME types
aoqi@0:      *                    default to US-ASCII.  Files are always autodetected since most
aoqi@0:      *                    file systems discard character encoding information.
aoqi@0:      */
aoqi@0:     public static InputSource createInputSource(String contentType,
aoqi@0:                                                 InputStream stream,
aoqi@0:                                                 boolean checkType,
aoqi@0:                                                 String scheme) throws IOException {
aoqi@0:         InputSource retval;
aoqi@0:         String charset = null;
aoqi@0: 
aoqi@0:         if (contentType != null) {
aoqi@0:             int index;
aoqi@0: 
aoqi@0:             contentType = contentType.toLowerCase();
aoqi@0:             index = contentType.indexOf(';');
aoqi@0:             if (index != -1) {
aoqi@0:                 String attributes;
aoqi@0: 
aoqi@0:                 attributes = contentType.substring(index + 1);
aoqi@0:                 contentType = contentType.substring(0, index);
aoqi@0: 
aoqi@0:                 // use "charset=..." if it's available
aoqi@0:                 index = attributes.indexOf("charset");
aoqi@0:                 if (index != -1) {
aoqi@0:                     attributes = attributes.substring(index + 7);
aoqi@0:                     // strip out subsequent attributes
aoqi@0:                     if ((index = attributes.indexOf(';')) != -1)
aoqi@0:                         attributes = attributes.substring(0, index);
aoqi@0:                     // find start of value
aoqi@0:                     if ((index = attributes.indexOf('=')) != -1) {
aoqi@0:                         attributes = attributes.substring(index + 1);
aoqi@0:                         // strip out rfc822 comments
aoqi@0:                         if ((index = attributes.indexOf('(')) != -1)
aoqi@0:                             attributes = attributes.substring(0, index);
aoqi@0:                         // double quotes are optional
aoqi@0:                         if ((index = attributes.indexOf('"')) != -1) {
aoqi@0:                             attributes = attributes.substring(index + 1);
aoqi@0:                             attributes = attributes.substring(0,
aoqi@0:                                     attributes.indexOf('"'));
aoqi@0:                         }
aoqi@0:                         charset = attributes.trim();
aoqi@0:                         // XXX "\;", "\)" etc were mishandled above
aoqi@0:                     }
aoqi@0:                 }
aoqi@0:             }
aoqi@0: 
aoqi@0:             //
aoqi@0:             // Check MIME type.
aoqi@0:             //
aoqi@0:             if (checkType) {
aoqi@0:                 boolean isOK = false;
aoqi@0:                 for (int i = 0; i < types.length; i++)
aoqi@0:                     if (types[i].equals(contentType)) {
aoqi@0:                         isOK = true;
aoqi@0:                         break;
aoqi@0:                     }
aoqi@0:                 if (!isOK)
aoqi@0:                     throw new IOException("Not XML: " + contentType);
aoqi@0:             }
aoqi@0: 
aoqi@0:             //
aoqi@0:             // "text/*" MIME types have hard-wired character set
aoqi@0:             // defaults, as specified in the RFCs.  For XML, we
aoqi@0:             // ignore the system "file.encoding" property since
aoqi@0:             // autodetection is more correct.
aoqi@0:             //
aoqi@0:             if (charset == null) {
aoqi@0:                 contentType = contentType.trim();
aoqi@0:                 if (contentType.startsWith("text/")) {
aoqi@0:                     if (!"file".equalsIgnoreCase(scheme))
aoqi@0:                         charset = "US-ASCII";
aoqi@0:                 }
aoqi@0:                 // "application/*" has no default
aoqi@0:             }
aoqi@0:         }
aoqi@0: 
aoqi@0:         retval = new InputSource(XmlReader.createReader(stream, charset));
aoqi@0:         retval.setByteStream(stream);
aoqi@0:         retval.setEncoding(charset);
aoqi@0:         return retval;
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Creates an input source from a given URI.
aoqi@0:      *
aoqi@0:      * @param uri       the URI (system ID) for the entity
aoqi@0:      * @param checkType if true, the MIME content type for the entity
aoqi@0:      *                  is checked for document type and character set encoding.
aoqi@0:      */
aoqi@0:     static public InputSource createInputSource(URL uri, boolean checkType)
aoqi@0:             throws IOException {
aoqi@0: 
aoqi@0:         URLConnection conn = uri.openConnection();
aoqi@0:         InputSource retval;
aoqi@0: 
aoqi@0:         if (checkType) {
aoqi@0:             String contentType = conn.getContentType();
aoqi@0:             retval = createInputSource(contentType, conn.getInputStream(),
aoqi@0:                     false, uri.getProtocol());
aoqi@0:         } else {
aoqi@0:             retval = new InputSource(XmlReader.createReader(conn.getInputStream()));
aoqi@0:         }
aoqi@0:         retval.setSystemId(conn.getURL().toString());
aoqi@0:         return retval;
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Creates an input source from a given file, autodetecting
aoqi@0:      * the character encoding.
aoqi@0:      */
aoqi@0:     static public InputSource createInputSource(File file)
aoqi@0:             throws IOException {
aoqi@0:         InputSource retval;
aoqi@0:         String path;
aoqi@0: 
aoqi@0:         retval = new InputSource(XmlReader.createReader(new FileInputStream(file)));
aoqi@0: 
aoqi@0:         // On JDK 1.2 and later, simplify this:
aoqi@0:         //    "path = file.toURL ().toString ()".
aoqi@0:         path = file.getAbsolutePath();
aoqi@0:         if (File.separatorChar != '/')
aoqi@0:             path = path.replace(File.separatorChar, '/');
aoqi@0:         if (!path.startsWith("/"))
aoqi@0:             path = "/" + path;
aoqi@0:         if (!path.endsWith("/") && file.isDirectory())
aoqi@0:             path = path + "/";
aoqi@0: 
aoqi@0:         retval.setSystemId("file:" + path);
aoqi@0:         return retval;
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * <b>SAX:</b>
aoqi@0:      * Resolve the given entity into an input source.  If the name can't
aoqi@0:      * be mapped to a preferred form of the entity, the URI is used.  To
aoqi@0:      * resolve the entity, first a local catalog mapping names to URIs is
aoqi@0:      * consulted.  If no mapping is found there, a catalog mapping names
aoqi@0:      * to java resources is consulted.  Finally, if neither mapping found
aoqi@0:      * a copy of the entity, the specified URI is used.
aoqi@0:      * <p/>
aoqi@0:      * <P> When a URI is used, <a href="#createInputSource">
aoqi@0:      * createInputSource</a> is used to correctly deduce the character
aoqi@0:      * encoding used by this entity.  No MIME type checking is done.
aoqi@0:      *
aoqi@0:      * @param name Used to find alternate copies of the entity, when
aoqi@0:      *             this value is non-null; this is the XML "public ID".
aoqi@0:      * @param uri  Used when no alternate copy of the entity is found;
aoqi@0:      *             this is the XML "system ID", normally a URI.
aoqi@0:      */
aoqi@0:     public InputSource resolveEntity(String name, String uri)
aoqi@0:             throws IOException {
aoqi@0:         InputSource retval;
aoqi@0:         String mappedURI = name2uri(name);
aoqi@0:         InputStream stream;
aoqi@0: 
aoqi@0:         // prefer explicit URI mappings, then bundled resources...
aoqi@0:         if (mappedURI == null && (stream = mapResource(name)) != null) {
aoqi@0:             uri = "java:resource:" + (String) id2resource.get(name);
aoqi@0:             retval = new InputSource(XmlReader.createReader(stream));
aoqi@0: 
aoqi@0:             // ...and treat all URIs the same (as URLs for now).
aoqi@0:         } else {
aoqi@0:             URL url;
aoqi@0:             URLConnection conn;
aoqi@0: 
aoqi@0:             if (mappedURI != null)
aoqi@0:                 uri = mappedURI;
aoqi@0:             else if (uri == null)
aoqi@0:                 return null;
aoqi@0: 
aoqi@0:             url = new URL(uri);
aoqi@0:             conn = url.openConnection();
aoqi@0:             uri = conn.getURL().toString();
aoqi@0:             // System.out.println ("++ URI: " + url);
aoqi@0:             if (ignoringMIME)
aoqi@0:                 retval = new InputSource(XmlReader.createReader(conn.getInputStream()));
aoqi@0:             else {
aoqi@0:                 String contentType = conn.getContentType();
aoqi@0:                 retval = createInputSource(contentType,
aoqi@0:                         conn.getInputStream(),
aoqi@0:                         false, url.getProtocol());
aoqi@0:             }
aoqi@0:         }
aoqi@0:         retval.setSystemId(uri);
aoqi@0:         retval.setPublicId(name);
aoqi@0:         return retval;
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Returns true if this resolver is ignoring MIME types in the documents
aoqi@0:      * it returns, to work around bugs in how servers have reported the
aoqi@0:      * documents' MIME types.
aoqi@0:      */
aoqi@0:     public boolean isIgnoringMIME() {
aoqi@0:         return ignoringMIME;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Tells the resolver whether to ignore MIME types in the documents it
aoqi@0:      * retrieves.  Many web servers incorrectly assign text documents a
aoqi@0:      * default character encoding, even when that is incorrect.  For example,
aoqi@0:      * all HTTP text documents default to use ISO-8859-1 (used for Western
aoqi@0:      * European languages), and other MIME sources default text documents
aoqi@0:      * to use US-ASCII (a seven bit encoding).  For XML documents which
aoqi@0:      * include text encoding declarations (as most should do), these server
aoqi@0:      * bugs can be worked around by ignoring the MIME type entirely.
aoqi@0:      */
aoqi@0:     public void setIgnoringMIME(boolean value) {
aoqi@0:         ignoringMIME = value;
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     // maps the public ID to an alternate URI, if one is registered
aoqi@0:     private String name2uri(String publicId) {
aoqi@0:         if (publicId == null || id2uri == null)
aoqi@0:             return null;
aoqi@0:         return (String) id2uri.get(publicId);
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Registers the given public ID as corresponding to a particular
aoqi@0:      * URI, typically a local copy.  This URI will be used in preference
aoqi@0:      * to ones provided as system IDs in XML entity declarations.  This
aoqi@0:      * mechanism would most typically be used for Document Type Definitions
aoqi@0:      * (DTDs), where the public IDs are formally managed and versioned.
aoqi@0:      *
aoqi@0:      * @param publicId The managed public ID being mapped
aoqi@0:      * @param uri      The URI of the preferred copy of that entity
aoqi@0:      */
aoqi@0:     public void registerCatalogEntry(String publicId,
aoqi@0:                                      String uri) {
aoqi@0:         if (id2uri == null)
aoqi@0:             id2uri = new Hashtable(17);
aoqi@0:         id2uri.put(publicId, uri);
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     // return the resource as a stream
aoqi@0:     private InputStream mapResource(String publicId) {
aoqi@0:         // System.out.println ("++ PUBLIC: " + publicId);
aoqi@0:         if (publicId == null || id2resource == null)
aoqi@0:             return null;
aoqi@0: 
aoqi@0:         String resourceName = (String) id2resource.get(publicId);
aoqi@0:         ClassLoader loader = null;
aoqi@0: 
aoqi@0:         if (resourceName == null)
aoqi@0:             return null;
aoqi@0:         // System.out.println ("++ Resource: " + resourceName);
aoqi@0: 
aoqi@0:         if (id2loader != null)
aoqi@0:             loader = (ClassLoader) id2loader.get(publicId);
aoqi@0:         // System.out.println ("++ Loader: " + loader);
aoqi@0:         if (loader == null)
aoqi@0:             return ClassLoader.getSystemResourceAsStream(resourceName);
aoqi@0:         return loader.getResourceAsStream(resourceName);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Registers a given public ID as corresponding to a particular Java
aoqi@0:      * resource in a given class loader, typically distributed with a
aoqi@0:      * software package.  This resource will be preferred over system IDs
aoqi@0:      * included in XML documents.  This mechanism should most typically be
aoqi@0:      * used for Document Type Definitions (DTDs), where the public IDs are
aoqi@0:      * formally managed and versioned.
aoqi@0:      * <p/>
aoqi@0:      * <P> If a mapping to a URI has been provided, that mapping takes
aoqi@0:      * precedence over this one.
aoqi@0:      *
aoqi@0:      * @param publicId     The managed public ID being mapped
aoqi@0:      * @param resourceName The name of the Java resource
aoqi@0:      * @param loader       The class loader holding the resource, or null if
aoqi@0:      *                     it is a system resource.
aoqi@0:      */
aoqi@0:     public void registerCatalogEntry(String publicId,
aoqi@0:                                      String resourceName,
aoqi@0:                                      ClassLoader loader) {
aoqi@0:         if (id2resource == null)
aoqi@0:             id2resource = new Hashtable(17);
aoqi@0:         id2resource.put(publicId, resourceName);
aoqi@0: 
aoqi@0:         if (loader != null) {
aoqi@0:             if (id2loader == null)
aoqi@0:                 id2loader = new Hashtable(17);
aoqi@0:             id2loader.put(publicId, loader);
aoqi@0:         }
aoqi@0:     }
aoqi@0: }