com.digitalpetri.opcua.stack.core.channel.headers.SequenceHeader.java Source code

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Here is the source code for com.digitalpetri.opcua.stack.core.channel.headers.SequenceHeader.java

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/*
 * Copyright 2015 Kevin Herron
 *
 * 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 com.digitalpetri.opcua.stack.core.channel.headers;

import com.digitalpetri.opcua.stack.core.util.annotations.UInt32Primitive;
import com.google.common.base.MoreObjects;
import io.netty.buffer.ByteBuf;

/**
 * The sequence header ensures that the first encrypted block of every Message sent over a channel will start with
 * different data.
 * <p>
 * SequenceNumbers may not be reused for any TokenId. The SecurityToken lifetime should be short enough to ensure that
 * this never happens; however, if it does the receiver should treat it as a transport error and force a reconnect.
 */
public class SequenceHeader {

    public static final int SEQUENCE_HEADER_SIZE = 8;

    @UInt32Primitive
    private final long sequenceNumber;

    @UInt32Primitive
    private final long requestId;

    /**
     * @param sequenceNumber a monotonically increasing sequence number assigned by the sender to each MessageChunk
     *                       sent over the SecureChannel.
     * @param requestId      an identifier assigned by the Client to OPC UA request Message. All MessageChunks for the
     *                       request and the associated response use the same identifier.
     */
    public SequenceHeader(long sequenceNumber, long requestId) {
        this.sequenceNumber = sequenceNumber;
        this.requestId = requestId;
    }

    public long getSequenceNumber() {
        return sequenceNumber;
    }

    public long getRequestId() {
        return requestId;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;

        SequenceHeader that = (SequenceHeader) o;

        return requestId == that.requestId && sequenceNumber == that.sequenceNumber;
    }

    @Override
    public int hashCode() {
        int result = (int) (sequenceNumber ^ (sequenceNumber >>> 32));
        result = 31 * result + (int) (requestId ^ (requestId >>> 32));
        return result;
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(this).add("sequenceNumber", sequenceNumber).add("requestId", requestId)
                .toString();
    }

    public static ByteBuf encode(SequenceHeader header, ByteBuf buffer) {
        buffer.writeInt((int) header.getSequenceNumber());
        buffer.writeInt((int) header.getRequestId());

        return buffer;
    }

    public static SequenceHeader decode(ByteBuf buffer) {
        return new SequenceHeader(buffer.readUnsignedInt(), /*    SequenceNumber  */
                buffer.readUnsignedInt() /*    RequestId       */
        );
    }

}