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The SNF4J module for TLS protocol
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/*
 * -------------------------------- MIT License --------------------------------
 * 
 * Copyright (c) 2022-2023 SNF4J contributors
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * -----------------------------------------------------------------------------
 */
package org.snf4j.tls.extension;

import java.nio.ByteBuffer;

import static org.snf4j.tls.handshake.HandshakeType.CLIENT_HELLO;

import org.snf4j.core.ByteBufferArray;
import org.snf4j.tls.Args;
import org.snf4j.tls.alert.Alert;
import org.snf4j.tls.handshake.HandshakeType;

public class SupportedVersionsExtension extends KnownExtension implements ISupportedVersionsExtension {

	private final static ExtensionType TYPE = ExtensionType.SUPPORTED_VERSIONS;
	
	private final Mode mode;
	
	private final int[] versions;
	
	private final static AbstractExtensionParser PARSER = new AbstractExtensionParser() {

		@Override
		public ExtensionType getType() {
			return TYPE;
		}

		@Override
		public IExtension parse(HandshakeType handshakeType, ByteBufferArray srcs, int remaining) throws Alert {
			if (remaining >= 2) {
				if (handshakeType.value() == CLIENT_HELLO.value()) {
					int len = srcs.getUnsigned();
					
					if ((len & 1) != 0 || len == 0) {
						throw decodeError("Incorrect length");
					}
					--remaining;
					if (len == remaining) {
						int[] versions = new int[len/2];
						
						for (int i=0; i