Add a Polatis SNMP driver

Change-Id: I4ba986d9e7aebb33cbce413b70393db16fc9ffcc
diff --git a/drivers/polatis/snmp/src/main/java/org/onosproject/drivers/polatis/snmp/PolatisSnmpUtility.java b/drivers/polatis/snmp/src/main/java/org/onosproject/drivers/polatis/snmp/PolatisSnmpUtility.java
new file mode 100644
index 0000000..654294f
--- /dev/null
+++ b/drivers/polatis/snmp/src/main/java/org/onosproject/drivers/polatis/snmp/PolatisSnmpUtility.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * 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.drivers.polatis.snmp;
+
+import org.onosproject.net.driver.DriverHandler;
+import org.onosproject.snmp.SnmpDevice;
+import org.onosproject.snmp.SnmpController;
+
+import org.snmp4j.CommunityTarget;
+import org.snmp4j.PDU;
+import org.snmp4j.Snmp;
+import org.snmp4j.event.ResponseEvent;
+import org.snmp4j.mp.SnmpConstants;
+import org.snmp4j.smi.Address;
+import org.snmp4j.smi.GenericAddress;
+import org.snmp4j.smi.OctetString;
+import org.snmp4j.smi.OID;
+import org.snmp4j.smi.VariableBinding;
+
+import java.io.IOException;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * SNP utility for Polatis SNMP drivers.
+ */
+public final class PolatisSnmpUtility {
+
+    private static final int MAX_SIZE_RESPONSE_PDU = 65535;
+
+    private PolatisSnmpUtility() {
+    }
+
+    private static SnmpDevice getDevice(DriverHandler handler) {
+        SnmpController controller = checkNotNull(handler.get(SnmpController.class));
+        SnmpDevice device = controller.getDevice(handler.data().deviceId());
+        return device;
+    }
+
+    private static CommunityTarget getTarget(DriverHandler handler) {
+        SnmpDevice device = getDevice(handler);
+        Address targetAddress = GenericAddress.parse(device.getProtocol() +
+                                                     ":" + device.getSnmpHost() +
+                                                     "/" + device.getSnmpPort());
+        CommunityTarget target = new CommunityTarget();
+        target.setCommunity(new OctetString(getDevice(handler).getCommunity()));
+        target.setAddress(targetAddress);
+        target.setRetries(3);
+        target.setTimeout(1000L * 3L);
+        target.setVersion(SnmpConstants.version2c);
+        target.setMaxSizeRequestPDU(MAX_SIZE_RESPONSE_PDU);
+        return target;
+    }
+
+    private static Snmp getSession(DriverHandler handler) {
+        Snmp session = getDevice(handler).getSession();
+        return session;
+    }
+
+    /**
+     * Sends a SET request.
+     *
+     * @param handler parent driver handler
+     * @param pdu SNMP protocol data unit
+     * @return the response event
+     * @throws IOException if unable to send a set request
+     */
+    public static ResponseEvent set(DriverHandler handler, PDU pdu) throws IOException {
+        Snmp session = getSession(handler);
+        CommunityTarget target = getTarget(handler);
+        return session.set(pdu, target);
+    }
+
+    /**
+     * Retrieves static object value.
+     *
+     * @param handler parent driver handler
+     * @param oid object identifier
+     * @return the string value
+     * @throws IOException if unable to retrieve the object value
+     */
+    public static String getOid(DriverHandler handler, String oid) throws IOException {
+        PDU pdu = new PDU();
+        pdu.add(new VariableBinding(new OID(oid)));
+        pdu.setType(PDU.GET);
+        Snmp session = getSession(handler);
+        CommunityTarget target = getTarget(handler);
+        ResponseEvent event = session.send(pdu, target);
+        return event.getResponse().get(0).getVariable().toString();
+    }
+}