[Emu][onos-2603] - Implement LinkState Link attributes-Route Tag

Change-Id: I75727ed7b62e6803245e6ff5f7a5665b6bd535ff

+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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.onosproject.bgpio.types.attr;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+import org.jboss.netty.buffer.ChannelBuffer;
+import org.onosproject.bgpio.exceptions.BGPParseException;
+import org.onosproject.bgpio.types.BGPErrorType;
+import org.onosproject.bgpio.types.BGPValueType;
+import org.onosproject.bgpio.util.Validation;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * Implements BGP prefix route tag attribute.
+ */
+public class BgpPrefixAttrRouteTag implements BGPValueType {
+
+    protected static final Logger log = LoggerFactory
+            .getLogger(BgpPrefixAttrRouteTag.class);
+
+    public static final int ATTR_PREFIX_ROUTETAG = 1153;
+
+    /* Prefix Route Tag */
+    private int[] pfxRouteTag;
+
+    /**
+     * Constructor to initialize the values.
+     *
+     * @param pfxRouteTag prefix route tag
+     */
+    BgpPrefixAttrRouteTag(int[] pfxRouteTag) {
+        this.pfxRouteTag = Arrays.copyOf(pfxRouteTag, pfxRouteTag.length);
+    }
+
+    /**
+     * Reads the Route Tag.
+     *
+     * @param cb ChannelBuffer
+     * @return object of BgpPrefixAttrRouteTag
+     * @throws BGPParseException while parsing BgpPrefixAttrRouteTag
+     */
+    public static BgpPrefixAttrRouteTag read(ChannelBuffer cb)
+            throws BGPParseException {
+        int[] pfxRouteTag;
+
+        short lsAttrLength = cb.readShort();
+        int len = lsAttrLength / Integer.SIZE;
+
+        if (cb.readableBytes() < lsAttrLength) {
+            Validation.validateLen(BGPErrorType.UPDATE_MESSAGE_ERROR,
+                                   BGPErrorType.ATTRIBUTE_LENGTH_ERROR,
+                                   lsAttrLength);
+        }
+
+        pfxRouteTag = new int[lsAttrLength];
+
+        for (int i = 0; i < len; i++) {
+            pfxRouteTag[i] = cb.readInt();
+        }
+
+        return new BgpPrefixAttrRouteTag(pfxRouteTag);
+    }
+
+    /**
+     * Returns the prefix route tag.
+     *
+     * @return route tag
+     */
+    int[] getPfxRouteTag() {
+        return pfxRouteTag;
+    }
+
+    @Override
+    public short getType() {
+        return ATTR_PREFIX_ROUTETAG;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(pfxRouteTag);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj instanceof BgpPrefixAttrRouteTag) {
+            BgpPrefixAttrRouteTag other = (BgpPrefixAttrRouteTag) obj;
+            return Objects.equals(pfxRouteTag, other.pfxRouteTag);
+        }
+        return false;
+    }
+
+    @Override
+    public int write(ChannelBuffer cb) {
+        // TODO This will be implemented in the next version
+        return 0;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass()).omitNullValues()
+                .add("pfxRouteTag", pfxRouteTag).toString();
+    }
+}