org.simplejavamail.utils.mail.smime.MimeUtil Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of utils-mail-smime Show documentation
An S/MIME library for JavaMail
There is a newer version: 2.3.11
/*
 * Copyright © 2021 Benny Bottema ([email protected])
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.simplejavamail.utils.mail.smime;

import jakarta.mail.MessagingException;
import jakarta.mail.internet.MimeBodyPart;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * Utilities for handling MIME messages from JavaMail.
 * 
 * @author Allen Petersen (akp at sourceforge dot net)
 * @author Torsten Krause (tk at markenwerk dot net)
 * @since 1.0.0
 */
final class MimeUtil {

	private MimeUtil() {
	}
	
	/**
	 * Translates a {@link MimeBodyPart} into its MIME-canonical form.
	 */
	static MimeBodyPart canonicalize(MimeBodyPart mimeBodyPart) throws MessagingException, IOException {
		ByteArrayOutputStream buffer = new ByteArrayOutputStream();
		OutputStream out = new MimeCanonicalOutputStream(buffer);
		mimeBodyPart.writeTo(out);
		out.close();
		return new MimeBodyPart(new ByteArrayInputStream(buffer.toByteArray()));
	}

	/**
	 * A stream which filters bytes, converting all occurrences of bare
	 * {@code \n} into {@code \r\n}.
	 */
	private static class MimeCanonicalOutputStream extends java.io.FilterOutputStream {

		int lastReadByte = -1;
		final byte[] crlf = new byte[] { (byte) '\r', (byte) '\n' };

		public MimeCanonicalOutputStream(java.io.OutputStream os) {
			super(os);
		}

		public void write(int b) throws java.io.IOException {
			if (b == '\r') {
				out.write(crlf);
			} else if (b == '\n') {
				if (lastReadByte != '\r')
					out.write(crlf);
			} else {
				out.write(b);
			}
			lastReadByte = b;
		}

		public void write(byte[] b) throws java.io.IOException {
			write(b, 0, b.length);
		}

		public void write(byte[] b, int off, int len) throws java.io.IOException {
			int start = off;

			len = off + len;
			for (int i = start; i < len; i++) {
				if (b[i] == '\r') {
					out.write(b, start, i - start);
					out.write(crlf);
					start = i + 1;
				} else if (b[i] == '\n') {
					if (lastReadByte != '\r') {
						out.write(b, start, i - start);
						out.write(crlf);
					}
					start = i + 1;
				}
				lastReadByte = b[i];
			}
			if ((len - start) > 0)
				out.write(b, start, len - start);
		}

	}
}