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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package com.sun.xml.internal.org.jvnet.mimepull;
import java.io.*;
/**
* This is a utility class that provides various MIME related
* functionality. <p>
*
* There are a set of methods to encode and decode MIME headers as
* per RFC 2047. Note that, in general, these methods are
* <strong>not</strong> needed when using methods such as
* <code>setSubject</code> and <code>setRecipients</code>; JavaMail
* will automatically encode and decode data when using these "higher
* level" methods. The methods below are only needed when maniuplating
* raw MIME headers using <code>setHeader</code> and <code>getHeader</code>
* methods. A brief description on handling such headers is given below: <p>
*
* RFC 822 mail headers <strong>must</strong> contain only US-ASCII
* characters. Headers that contain non US-ASCII characters must be
* encoded so that they contain only US-ASCII characters. Basically,
* this process involves using either BASE64 or QP to encode certain
* characters. RFC 2047 describes this in detail. <p>
*
* In Java, Strings contain (16 bit) Unicode characters. ASCII is a
* subset of Unicode (and occupies the range 0 - 127). A String
* that contains only ASCII characters is already mail-safe. If the
* String contains non US-ASCII characters, it must be encoded. An
* additional complexity in this step is that since Unicode is not
* yet a widely used charset, one might want to first charset-encode
* the String into another charset and then do the transfer-encoding.
* <p>
* Note that to get the actual bytes of a mail-safe String (say,
* for sending over SMTP), one must do
* <p><blockquote><pre>
*
* byte[] bytes = string.getBytes("iso-8859-1");
*
* </pre></blockquote><p>
*
* The <code>setHeader</code> and <code>addHeader</code> methods
* on MimeMessage and MimeBodyPart assume that the given header values
* are Unicode strings that contain only US-ASCII characters. Hence
* the callers of those methods must insure that the values they pass
* do not contain non US-ASCII characters. The methods in this class
* help do this. <p>
*
* The <code>getHeader</code> family of methods on MimeMessage and
* MimeBodyPart return the raw header value. These might be encoded
* as per RFC 2047, and if so, must be decoded into Unicode Strings.
* The methods in this class help to do this. <p>
*
* Several System properties control strict conformance to the MIME
* spec. Note that these are not session properties but must be set
* globally as System properties. <p>
*
* The <code>mail.mime.decodetext.strict</code> property controls
* decoding of MIME encoded words. The MIME spec requires that encoded
* words start at the beginning of a whitespace separated word. Some
* mailers incorrectly include encoded words in the middle of a word.
* If the <code>mail.mime.decodetext.strict</code> System property is
* set to <code>"false"</code>, an attempt will be made to decode these
* illegal encoded words. The default is true. <p>
*
* The <code>mail.mime.encodeeol.strict</code> property controls the
* choice of Content-Transfer-Encoding for MIME parts that are not of
* type "text". Often such parts will contain textual data for which
* an encoding that allows normal end of line conventions is appropriate.
* In rare cases, such a part will appear to contain entirely textual
* data, but will require an encoding that preserves CR and LF characters
* without change. If the <code>mail.mime.encodeeol.strict</code>
* System property is set to <code>"true"</code>, such an encoding will
* be used when necessary. The default is false. <p>
*
* In addition, the <code>mail.mime.charset</code> System property can
* be used to specify the default MIME charset to use for encoded words
* and text parts that don't otherwise specify a charset. Normally, the
* default MIME charset is derived from the default Java charset, as
* specified in the <code>file.encoding</code> System property. Most
* applications will have no need to explicitly set the default MIME
* charset. In cases where the default MIME charset to be used for
* mail messages is different than the charset used for files stored on
* the system, this property should be set. <p>
*
* The current implementation also supports the following System property.
* <p>
* The <code>mail.mime.ignoreunknownencoding</code> property controls
* whether unknown values in the <code>Content-Transfer-Encoding</code>
* header, as passed to the <code>decode</code> method, cause an exception.
* If set to <code>"true"</code>, unknown values are ignored and 8bit
* encoding is assumed. Otherwise, unknown values cause a MessagingException
* to be thrown.
*
* @author John Mani
* @author Bill Shannon
*/
/* FROM mail.jar */
final class MimeUtility {
// This class cannot be instantiated
private MimeUtility() { }
private static final boolean ignoreUnknownEncoding =
PropUtil.getBooleanSystemProperty(
"mail.mime.ignoreunknownencoding", false);
/**
* Decode the given input stream. The Input stream returned is
* the decoded input stream. All the encodings defined in RFC 2045
* are supported here. They include "base64", "quoted-printable",
* "7bit", "8bit", and "binary". In addition, "uuencode" is also
* supported. <p>
*
* In the current implementation, if the
* <code>mail.mime.ignoreunknownencoding</code> system property is set to
* <code>"true"</code>, unknown encoding values are ignored and the
* original InputStream is returned.
*
* @param is input stream
* @param encoding the encoding of the stream.
* @return decoded input stream.
* @exception MessagingException if the encoding is unknown
*/
public static InputStream decode(InputStream is, String encoding)
throws DecodingException {
if (encoding.equalsIgnoreCase("base64"))
return new BASE64DecoderStream(is);
else if (encoding.equalsIgnoreCase("quoted-printable"))
return new QPDecoderStream(is);
else if (encoding.equalsIgnoreCase("uuencode") ||
encoding.equalsIgnoreCase("x-uuencode") ||
encoding.equalsIgnoreCase("x-uue"))
return new UUDecoderStream(is);
else if (encoding.equalsIgnoreCase("binary") ||
encoding.equalsIgnoreCase("7bit") ||
encoding.equalsIgnoreCase("8bit"))
return is;
else {
if (!ignoreUnknownEncoding) {
throw new DecodingException("Unknown encoding: " + encoding);
}
return is;
}
}
}