ONOS-2402 Add L4 modification instruction type and class

Change-Id: I74fec41f865191371a908cef86c00218f8a1a203

@@ -62,7 +62,12 @@ public interface Instruction {
         /**
          * Signifies that metadata be attached to traffic.
          */
-        METADATA
+        METADATA,
+
+        /**
+         * Signifies that the traffic should be modified in L4 way.
+         */
+        L4MODIFICATION
     }
 
     /**

+/*
+ * Copyright 2014-2015 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.net.flow.instructions;
+
+import java.util.Objects;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+
+/**
+ * Abstraction of a single traffic treatment step.
+ */
+public abstract class L4ModificationInstruction implements Instruction {
+
+    /**
+     * Represents the type of traffic treatment.
+     */
+    public enum L4SubType {
+        /**
+         * TCP src modification.
+         */
+        TCP_SRC,
+
+        /**
+         * TCP dst modification.
+         */
+        TCP_DST,
+
+        /**
+         * UDP src modification.
+         */
+        UDP_SRC,
+
+        /**
+         * UDP dst modification.
+         */
+        UDP_DST
+
+        //TODO: remaining types
+    }
+
+    /**
+     * Returns the subtype of the modification instruction.
+     *
+     * @return type of instruction
+     */
+    public abstract L4SubType subtype();
+
+    @Override
+    public Type type() {
+        return Type.L4MODIFICATION;
+    }
+
+    /**
+     * Represents a L4 src/dst modification instruction.
+     */
+    public static final class ModL4PortInstruction extends L4ModificationInstruction {
+
+        private final L4SubType subtype;
+        private final short port;
+
+        public ModL4PortInstruction(L4SubType subtype, short port) {
+            this.subtype = subtype;
+            this.port = port;
+        }
+
+        @Override
+        public L4SubType subtype() {
+            return this.subtype;
+        }
+
+        public short port() {
+            return this.port;
+        }
+
+        @Override
+        public String toString() {
+            return toStringHelper(subtype().toString())
+                    .add("port", port).toString();
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(type(), subtype(), port);
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (obj instanceof ModL4PortInstruction) {
+                ModL4PortInstruction that = (ModL4PortInstruction) obj;
+                return  Objects.equals(port, that.port) &&
+                        Objects.equals(this.subtype(), that.subtype());
+            }
+            return false;
+        }
+    }
+}