package org.sentrysoftware.ipmi.core.api.sol;
   
   /*-
    * ╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲
    * IPMI Java Client
    * ჻჻჻჻჻჻
    * Copyright 2023 Verax Systems, Sentry Software
    * ჻჻჻჻჻჻
    * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as
   * published by the Free Software Foundation, either version 3 of the
   * License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Lesser Public License for more details.
   *
   * You should have received a copy of the GNU General Lesser Public
   * License along with this program.  If not, see
   * <http://www.gnu.org/licenses/lgpl-3.0.html>.
   * ╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱
   */
  
  import org.sentrysoftware.ipmi.core.api.async.ConnectionHandle;
  import org.sentrysoftware.ipmi.core.api.async.InboundSolMessageListener;
  import org.sentrysoftware.ipmi.core.api.sync.IpmiConnector;
  import org.sentrysoftware.ipmi.core.coding.PayloadCoder;
  import org.sentrysoftware.ipmi.core.coding.commands.IpmiVersion;
  import org.sentrysoftware.ipmi.core.coding.commands.PrivilegeLevel;
  import org.sentrysoftware.ipmi.core.coding.commands.payload.ActivateSolPayload;
  import org.sentrysoftware.ipmi.core.coding.commands.payload.ActivateSolPayloadResponseData;
  import org.sentrysoftware.ipmi.core.coding.commands.payload.DeactivatePayload;
  import org.sentrysoftware.ipmi.core.coding.commands.payload.GetPayloadActivationStatus;
  import org.sentrysoftware.ipmi.core.coding.commands.payload.GetPayloadActivationStatusResponseData;
  import org.sentrysoftware.ipmi.core.coding.commands.session.SetSessionPrivilegeLevel;
  import org.sentrysoftware.ipmi.core.coding.payload.CompletionCode;
  import org.sentrysoftware.ipmi.core.coding.payload.lan.IPMIException;
  import org.sentrysoftware.ipmi.core.coding.payload.sol.SolAckState;
  import org.sentrysoftware.ipmi.core.coding.payload.sol.SolMessage;
  import org.sentrysoftware.ipmi.core.coding.payload.sol.SolOperation;
  import org.sentrysoftware.ipmi.core.coding.protocol.AuthenticationType;
  import org.sentrysoftware.ipmi.core.coding.protocol.PayloadType;
  import org.sentrysoftware.ipmi.core.coding.security.CipherSuite;
  import org.sentrysoftware.ipmi.core.coding.sol.SolCoder;
  import org.sentrysoftware.ipmi.core.coding.sol.SolResponseData;
  import org.sentrysoftware.ipmi.core.common.Constants;
  import org.sentrysoftware.ipmi.core.common.TypeConverter;
  import org.sentrysoftware.ipmi.core.connection.Session;
  import org.sentrysoftware.ipmi.core.connection.SessionException;
  import org.sentrysoftware.ipmi.core.connection.SessionManager;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.util.Arrays;
  import java.util.HashSet;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Set;
  
  /**
   * Entry point for the Serial Over LAN (SOL) communication. Use all SOL operations through this class.
   */
  public class SerialOverLan implements Closeable {
  
      private static final Logger logger = LoggerFactory.getLogger(SerialOverLan.class);
  
      private final IpmiConnector connector;
      private final Session session;
      private final InboundSolMessageListener inboundMessageListener;
      private final List<SolEventListener> eventListeners;
  
      private boolean isSessionInternal;
      private int payloadInstance;
      private int maxPayloadSize;
      private boolean closed;
  
      /**
       * Creates connection with IPMI using given {@link IpmiConnector}, connected to remote machine on given address and port,
       * and opens a new {@link Session} for SOL communication.
       * This constructor should be used only when you have no other connection opened on this port.
       *
       * @param connector
       *          {@link IpmiConnector} that will be used for communication
       * @param remoteHost
       *          IP address of the remote server
       * @param remotePort
       *          UDP port number of the remote server
       * @param user
       *          IPMI user name
       * @param password
       *          IPMI password
       * @param cipherSuiteSelectionHandler
       *          {@link CipherSuiteSelectionHandler} that will allow to select {@link CipherSuite} among available ones.
       *
      * @throws SOLException when any problem occur during establishing session or activating SOL payload.
      */
     public SerialOverLan(IpmiConnector connector, String remoteHost, int remotePort, String user, String password,
                          CipherSuiteSelectionHandler cipherSuiteSelectionHandler) throws SOLException, SessionException {
         this(connector, SessionManager.establishSession(connector, remoteHost, remotePort, user, password, cipherSuiteSelectionHandler));
 
         this.isSessionInternal = true;
     }
 
     /**
      * Creates connection with IPMI using given {@link IpmiConnector}, connected to remote machine on given address and default IPMI port,
      * and opens a new {@link Session} for SOL communication.
      * This constructor should be used only when you have no other connection opened on this port.
      *
      * @param connector
      *          {@link IpmiConnector} that will be used for communication
      * @param remoteHost
      *          IP address of the remote server
      * @param user
      *          IPMI user name
      * @param password
      *          IPMI password
      * @param cipherSuiteSelectionHandler
      *          {@link CipherSuiteSelectionHandler} that will allow to select {@link CipherSuite} among available ones.
      *
      * @throws SOLException when any problem occur during establishing session or activating SOL payload.
      */
     public SerialOverLan(IpmiConnector connector, String remoteHost, String user, String password,
                          CipherSuiteSelectionHandler cipherSuiteSelectionHandler) throws SOLException, SessionException {
         this(connector, remoteHost, Constants.IPMI_PORT, user, password, cipherSuiteSelectionHandler);
     }
 
     /**
      * Tries to open SOL communication on given existing session. When it appears that separate session must be opened
      * to handle SOL messages (for example SOL payload must be activated on separate port), the new connection and session
      * are automatically established.
      *
      * @param connector
      *          {@link IpmiConnector} that will be used for communication
      * @param session
      *          Existing session that should be reused (if possible) for SOL communication.
      */
     public SerialOverLan(IpmiConnector connector, Session session) throws SOLException, SessionException {
         this.connector = connector;
 
         int solPayloadPort = activatePayload(connector, session.getConnectionHandle());
 
         this.session = resolveSession(connector, session.getConnectionHandle(), session, solPayloadPort);
 
         this.eventListeners = new LinkedList<SolEventListener>();
         this.inboundMessageListener = new InboundSolMessageListener(connector,
                 this.session.getConnectionHandle(), eventListeners);
 
         connector.registerIncomingMessageListener(inboundMessageListener);
         this.closed = false;
     }
 
     /**
      * Given potential session object, connection data and port on which SOL should be activated,
      * decides what session should be finally used to SOL communication.
      *
      * @param connector
      *          {@link IpmiConnector} that will be used for communication
      * @param connectionHandle
      *          {@link ConnectionHandle} representing single connection to managed system.
      * @param session
      *          Existing session that should be reused (if possible) for SOL communication.
      * @param solPayloadPort
      *          UDP port on which managed system listens for SOL communication.
      * @return Actual session (existing or newly established), that should be used for SOL communication.
      * @throws SOLException
      *          If any unrecoverable error occurs.
      * @throws SessionException
      *          If new session could not be established.
      */
     private Session resolveSession(IpmiConnector connector, ConnectionHandle connectionHandle, Session session, int solPayloadPort) throws SOLException, SessionException {
         if (solPayloadPort != connectionHandle.getRemotePort()) {
             Session alternativeSession = connector.getExistingSessionForCriteria(connectionHandle.getRemoteAddress(),
                     solPayloadPort, connectionHandle.getUser());
 
             if (alternativeSession == null) {
                 CipherSuiteSelectionHandler cipherSuiteSelector = new SpecificCipherSuiteSelector(connectionHandle.getCipherSuite());
 
                 alternativeSession = SessionManager.establishSession(connector, connectionHandle.getRemoteAddress().getHostAddress(),
                         solPayloadPort, connectionHandle.getUser(), connectionHandle.getPassword(), cipherSuiteSelector);
                 this.isSessionInternal = true;
 
             } else {
                 this.isSessionInternal = false;
             }
 
             activatePayload(connector, alternativeSession.getConnectionHandle());
 
             return alternativeSession;
         } else {
             this.isSessionInternal = false;
             return session;
         }
     }
 
     /**
      * Tries to activate SOL payload in the session associated to given {@link ConnectionHandle}.
      * If first activation try fails due to insufficient privileges, raises the session privileges
      * to maximum available and tries to activate payload once again.
      *
      * @param connector
      *          {@link IpmiConnector} that will be used for communication
      * @param connectionHandle
      *          {@link ConnectionHandle} representing single connection to managed system.
      * @return UDP port number on which managed system listenes for SOL messages.
      * @throws SOLException
      *          when any unrecoverable error occurred.
      */
     private int activatePayload(IpmiConnector connector, ConnectionHandle connectionHandle) throws SOLException {
         try {
             this.payloadInstance = getFirstAvailablePayloadInstance(connector, connectionHandle);
 
             ActivateSolPayload activatePayload = new ActivateSolPayload(connectionHandle.getCipherSuite(), payloadInstance);
             ActivateSolPayloadResponseData activatePayloadResponseData = getActivatePayloadResponse(connector,
                     connectionHandle, activatePayload);
 
             this.maxPayloadSize = activatePayloadResponseData.getInboundPayloadSize();
 
             return activatePayloadResponseData.getPayloadUdpPortNumber();
 
         } catch (Exception e) {
             throw new SOLException("Cannot activate SOL payload due to exception during activation process", e);
         }
     }
 
     private ActivateSolPayloadResponseData getActivatePayloadResponse(IpmiConnector connector, ConnectionHandle connectionHandle, ActivateSolPayload activatePayload) throws Exception {
         ActivateSolPayloadResponseData activatePayloadResponseData;
 
         try {
             activatePayloadResponseData = (ActivateSolPayloadResponseData) connector.sendMessage(connectionHandle,
                     activatePayload);
         } catch (IPMIException e) {
             if (e.getCompletionCode() == CompletionCode.InsufficentPrivilege) {
                 raiseSessionPrivileges(connector, connectionHandle);
 
                 activatePayloadResponseData = (ActivateSolPayloadResponseData) connector.sendMessage(
                         connectionHandle, activatePayload);
             } else {
                 throw e;
             }
         }
 
         return activatePayloadResponseData;
     }
 
     /**
      * Checks for available SOL payload instances and, if any, returns first available.
      *
      * @param connector
      *          {@link IpmiConnector} that will be used for communication
      * @param connectionHandle
      *          {@link ConnectionHandle} representing single connection to managed system.
      * @return number of first available SOL payload instance.
      * @throws Exception
      *          If any exception occurred during communication or if no available instances were found.
      */
     private int getFirstAvailablePayloadInstance(IpmiConnector connector, ConnectionHandle connectionHandle) throws Exception {
         GetPayloadActivationStatus getPayloadActivationStatus = new GetPayloadActivationStatus(connectionHandle.getCipherSuite(),
                 PayloadType.Sol);
         GetPayloadActivationStatusResponseData getActivationResponseData = (GetPayloadActivationStatusResponseData) connector.sendMessage(
                 connectionHandle, getPayloadActivationStatus);
 
         if (getActivationResponseData.getInstanceCapacity() <= 0 || getActivationResponseData.getAvailableInstances().isEmpty()) {
             throw new SOLException("Cannot activate SOL payload, as there are no available payload instances.");
         }
 
         return TypeConverter.byteToInt(getActivationResponseData.getAvailableInstances().get(0));
     }
 
     /**
      * Sends proper command to managed system in order to raise user privileges in given session to maximum available level.
      *
      * @param connector
      *          {@link IpmiConnector} that will be used for communication
      * @param connectionHandle
      *          {@link ConnectionHandle} representing single connection to managed system.
      * @throws Exception
      *           If any exception occurred during communication.
      */
     private void raiseSessionPrivileges(IpmiConnector connector, ConnectionHandle connectionHandle) throws Exception {
         SetSessionPrivilegeLevel setSessionPrivilegeLevel = new SetSessionPrivilegeLevel(IpmiVersion.V20,
                 connectionHandle.getCipherSuite(), AuthenticationType.RMCPPlus, PrivilegeLevel.Administrator);
         connector.sendMessage(connectionHandle, setSessionPrivilegeLevel);
     }
 
 
     /**
      * Writes single byte to the port.
      * This operation blocks until all data can be sent to remote server and is either accepted or rejected by the server.
      *
      * @param singleByte
      *          a byte to write
      * @return true if byte was successfully sent and acknowledged by remote server, false otherwise.
      */
     public boolean writeByte(byte singleByte) {
        return writeBytes(new byte[] {singleByte});
     }
 
     /**
      * Writes bytes array to the port.
      * This operation blocks until all data can be sent to remote server and is either accepted or rejected by the server.
      *
      * @param buffer
      *          an array of bytes to write
      * @return true if all bytes were successfully sent and acknowledged by remote server, false otherwise.
      */
     public boolean writeBytes(byte[] buffer) {
         boolean result = true;
 
         int maxBufferSize = maxPayloadSize - SolMessage.PAYLOAD_HEADER_LENGTH;
         byte[] remainingBytes = buffer;
         int currentIndex = 0;
 
         while (remainingBytes.length - currentIndex > maxBufferSize) {
             byte[] bufferChunk = Arrays.copyOfRange(remainingBytes, currentIndex, maxBufferSize);
             currentIndex += maxBufferSize;
 
             result &= sendMessage(bufferChunk);
 
             if (!result) {
                 return false;
             }
         }
 
         if (remainingBytes.length - currentIndex > 0) {
             remainingBytes = Arrays.copyOfRange(remainingBytes, currentIndex, remainingBytes.length);
             result &= sendMessage(remainingBytes);
         }
 
         return result;
     }
 
     /**
      * Writes single integer (in range from 0 to 255) to the port.
      * This operation blocks until all data can be sent to remote server and is either accepted or rejected by the server.
      *
      * @param singleInt
      *          an integer value to write (must be in range from 0 to 255)
      * @return true if integer was successfully sent and acknowledged by remote server, false otherwise.
      */
     public boolean writeInt(int singleInt) {
         return writeBytes(new byte[] {TypeConverter.intToByte(singleInt)});
     }
 
     /**
      * Writes integers (in range from 0 to 255) array to the port.
      * This operation blocks until all data can be sent to remote server and is either accepted or rejected by the server.
      *
      * @param buffer
      *          an array of integer values to write (each must be in range from 0 to 255)
      * @return true if all integers were successfully sent and acknowledged by remote server, false otherwise.
      */
     public boolean writeIntArray(int[] buffer) {
         byte[] byteBuffer = new byte[buffer.length];
 
         for (int i = 0; i < buffer.length; i++) {
             byteBuffer[i] = TypeConverter.intToByte(buffer[i]);
         }
 
         return writeBytes(byteBuffer);
     }
 
     /**
      * Writes {@link String} to port, using platform's default {@link Charset} when converting {@link String} to byte array.
      * This operation blocks until all data can be sent to remote server and is either accepted or rejected by the server.
      *
      * @param string
      *          a string to write to the port.
      * @return true if whole string was successfully sent and acknowledged by remote server, false otherwise.
      */
     public boolean writeString(String string) {
         return writeBytes(string.getBytes());
     }
 
     /**
      * Writes {@link String} to port, using given {@link Charset} when converting {@link String} to byte array.
      * This operation blocks until all data can be sent to remote server and is either accepted or rejected by the server.
      *
      * @param string
      *          a string to write to port
      * @param charset
      *          {@link Charset} that the string is encoded in
      * @return true if whole string was successfully sent and acknowledged by remote server, false otherwise.
      */
     public boolean writeString(String string, Charset charset) {
         return writeBytes(string.getBytes(charset));
     }
 
     /**
      * Read all available bytes from the port.
      * Returns immediately, without waiting for data to be available.
      *
      * @return all bytes that could be read or empty array if no bytes were available.
      */
     public byte[] readBytes() {
         return readBytes(inboundMessageListener.getAvailableBytesCount());
     }
 
     /**
      * Reads at max given number of bytes from the port.
      * Returns immediately, without waiting for data to be available.
      *
      * @param byteCount
      *          maximum number of bytes that should be read
      * @return byte array containing bytes that could be read, but no more than given byteCount.
      * Returns empty array if no bytes were available.
      */
     public byte[] readBytes(int byteCount) {
         return inboundMessageListener.readBytes(byteCount);
     }
 
     /**
      * Reads at max given number of bytes from the port.
      * This operation blocks until given number of bytes is available to be read or until given timeout is hit.
      *
      * @param byteCount
      *          maximum number of bytes that should be read.
      * @param timeout
      *          maximum time in milliseconds that we want to wait for all available bytes
      * @return byte array containing bytes that could be read, but no more than byteCount.
      * When the timeout is hit, returns just bytes that were available or empty array if no bytes were available.
      */
     public byte[] readBytes(int byteCount, int timeout) {
         waitForData(byteCount, timeout);
 
         return readBytes(byteCount);
     }
 
     /**
      * Reads all available bytes from the port as integer (in range from 0 to 255) values array.
      * Returns immediately, without waiting for data to be available.
      *
      * @return all bytes that could be read as int array (each value in range from 0 to 255) or empty array if no data was available.
      */
     public int[] readIntArray() {
         return readIntArray(inboundMessageListener.getAvailableBytesCount());
     }
 
     /**
      * Reads at max given number of integer values (in range from 0 to 255) from the port.
      * Returns immediately, without waiting for data to be available.
      *
      * @param byteCount
      *          maximum number of bytes that should be read
      * @return integer array containing integer values that could be read, but no more than given byteCount (each value in range from 0 to 255).
      * Returns empty array if no data was available.
      */
     public int[] readIntArray(int byteCount) {
         byte[] bytesArray = readBytes(byteCount);
         int[] intArray = new int[bytesArray.length];
 
         for (int i = 0; i < bytesArray.length; i++) {
             intArray[i] = TypeConverter.byteToInt(bytesArray[i]);
         }
 
         return intArray;
     }
 
     /**
      * Reads at max given number of integer values (in range from 0 to 255) from the port.
      * This operation blocks until given number of bytes is available to be read or until given timeout is hit.
      *
      * @param byteCount
      *          maximum number of bytes that should be read.
      * @param timeout
      *          maximum time in milliseconds that we want to wait for all available data
      * @return integer array containing integer values that could be read, but no more than byteCount (each value in range from 0 to 255).
      * When the timeout is hit, returns just data that was available or empty array if no data was available.
      */
     public int[] readIntArray(int byteCount, int timeout) {
         waitForData(byteCount, timeout);
 
         return readIntArray(byteCount);
     }
 
     /**
      * Read all available bytes from the port and converts them to {@link String} using platform's default {@link Charset}.
      * Returns immediately, without waiting for data to be available.
      *
      * @return all bytes that could be read as {@link String}.
      */
     public String readString() {
         return readString(inboundMessageListener.getAvailableBytesCount());
     }
 
     /**
      * Reads at max given number of bytes from the port, converting them to {@link String} using platform's default {@link Charset}.
      * Returns immediately, without waiting for data to be available.
      *
      * @param byteCount
      *          maximum number of bytes that should be read
      * @return all bytes that could be read as {@link String}, but no more than given byteCount.
      */
     public String readString(int byteCount) {
         return new String(readBytes(byteCount));
     }
 
     /**
      * Reads at max given number of bytes from the port, converting them to {@link String} using platform's default {@link Charset}.
      * This operation blocks until given number of bytes is available to be read or until given timeout is hit.
      *
      * @param byteCount
      *          maximum number of bytes that should be read.
      * @param timeout
      *          maximum time in milliseconds that we want to wait for all available bytes
      * @return all bytes that could be read as {@link String}, but no more than given byteCount.
      * When the timeout is hit, returns just bytes that were available.
      */
     public String readString(int byteCount, int timeout) {
         waitForData(byteCount, timeout);
 
         return readString(byteCount);
     }
 
     /**
      * Read all available bytes from the port and converts them to {@link String} using given {@link Charset}.
      * Returns immediately, without waiting for data to be available.
      *
      * @param charset
      *          {@link Charset} that will be used when converting bytes to {@link String}
      * 
      * @return all bytes that could be read as {@link String}.
      */
     public String readString(Charset charset) {
         return readString(charset, inboundMessageListener.getAvailableBytesCount());
     }
 
     /**
      * Reads at max given number of bytes from the port, converting them to {@link String} using given {@link Charset}.
      * Returns immediately, without waiting for data to be available.
      *
      * @param charset
      *          {@link Charset} that will be used when converting bytes to {@link String}
      * @param byteCount
      *          maximum number of bytes that should be read
      * @return all bytes that could be read as {@link String}, but no more than given byteCount.
      */
     public String readString(Charset charset, int byteCount) {
         return new String(readBytes(byteCount), charset);
     }
 
     /**
      * Reads at max given number of bytes from the port, converting them to {@link String} using given {@link Charset}.
      * This operation blocks until given number of bytes is available to be read or until given timeout is hit.
      *
      * @param charset
      *          {@link Charset} that will be used when converting bytes to {@link String}
      * @param byteCount
      *          maximum number of bytes that should be read.
      * @param timeout
      *          maximum time in milliseconds that we want to wait for all available bytes
      * @return all bytes that could be read as {@link String}, but no more than given byteCount.
      * When the timeout is hit, returns just bytes that were available.
      */
     public String readString(Charset charset, int byteCount, int timeout) {
         waitForData(byteCount, timeout);
 
         return readString(charset, byteCount);
     }
 
     private void waitForData(int wantedByteCount, int timeout) {
         long startTime = System.currentTimeMillis();
 
         while (isTooFewBytesAvailable(wantedByteCount) && timeoutNotHit(timeout, startTime)) {
             // NOP, just waiting
         }
     }
 
     private boolean isTooFewBytesAvailable(int wantedByteCount) {
         return inboundMessageListener.getAvailableBytesCount() < wantedByteCount;
     }
 
     private boolean timeoutNotHit(int timeout, long startTime) {
         return System.currentTimeMillis() - startTime < timeout;
     }
 
     /**
      * Invokes given SOL-specific operations on remote serial port.
      *
      * @param operations
      *          a bunch of {@link SolOperation}s that should be invoked
      * @return true if operations were successfully sent and acknowledged by remote server, false otherwise.
      */
     public boolean invokeOperations(SolOperation... operations) {
         Set<SolOperation> operationSet = new HashSet<SolOperation>();
 
         for (SolOperation operation : operations) {
             operationSet.add(operation);
         }
 
         return sendMessage(operationSet);
     }
 
     /**
      * Registers new {@link SolEventListener} that will be informed about SOL events fired by remote system.
      *
      * @param listener
      *          listener to be registered
      */
     public void registerEventListener(SolEventListener listener) {
         eventListeners.add(listener);
     }
 
     /**
      * Unregister given {@link SolEventListener}, preventing it from receiving SOL events from remote server.
      *
      * @param listener
      *          listener to be unregistered
      */
     public void unregisterEventListener(SolEventListener listener) {
         eventListeners.remove(listener);
     }
 
     private boolean sendMessage(byte[] characterData) {
         SolCoder payloadCoder = new SolCoder(characterData, session.getConnectionHandle().getCipherSuite());
 
         SolResponseData responseData = sendPayload(payloadCoder);
 
         notifyResponseListeners(characterData, new HashSet<SolOperation>(), responseData);
 
         byte[] remainingCharacterData = characterData;
 
         while (isNackForMessagePart(responseData, remainingCharacterData.length)) {
             remainingCharacterData = Arrays.copyOfRange(remainingCharacterData,
                     responseData.getAcceptedCharactersNumber(), remainingCharacterData.length);
 
             SolCoder partialPayloadCoder = new SolCoder(remainingCharacterData, session.getConnectionHandle().getCipherSuite());
             responseData = sendPayload(partialPayloadCoder);
 
             notifyResponseListeners(remainingCharacterData, new HashSet<SolOperation>(), responseData);
         }
 
         return responseData != null && responseData.getAcknowledgeState() == SolAckState.ACK;
     }
 
     private boolean sendMessage(Set<SolOperation> operations) {
         SolCoder payloadCoder = new SolCoder(operations, session.getConnectionHandle().getCipherSuite());
 
         SolResponseData responseData = sendPayload(payloadCoder);
 
         notifyResponseListeners(new byte[0], operations, responseData);
 
         return responseData != null && responseData.getAcknowledgeState() == SolAckState.ACK;
     }
 
     private void notifyResponseListeners(byte[] characterData, Set<SolOperation> solOperations, SolResponseData responseData) {
         if (responseData != null && responseData.getStatuses() != null && !responseData.getStatuses().isEmpty()) {
             for (SolEventListener listener : eventListeners) {
                 listener.processResponseEvent(responseData.getStatuses(), characterData, solOperations);
             }
         }
     }
 
     private SolResponseData sendPayload(PayloadCoder payloadCoder) {
         ConnectionHandle connectionHandle = session.getConnectionHandle();
 
         try {
             SolResponseData responseData = (SolResponseData) connector.sendMessage(connectionHandle, payloadCoder);
 
             int actualRetries = 0;
 
             while (isNackForWholeMessage(responseData) && actualRetries < connector.getRetries()) {
                 actualRetries++;
 
                 responseData = (SolResponseData) connector.retryMessage(connectionHandle,
                         responseData.getRequestSequenceNumber(), PayloadType.Sol);
             }
 
             return responseData;
         } catch (Exception e) {
             logger.error("Error while sending message", e);
             return null;
         }
     }
 
     @Override
     public synchronized void close() throws IOException {
         if (!closed) {
             try {
                 ConnectionHandle connectionHandle = session.getConnectionHandle();
 
                 DeactivatePayload deactivatePayload = new DeactivatePayload(connectionHandle.getCipherSuite(),
                         PayloadType.Sol, payloadInstance);
 
                 connector.sendMessage(connectionHandle, deactivatePayload);
 
                 if (isSessionInternal) {
                     connector.closeSession(connectionHandle);
                     connector.tearDown();
                 }
 
                 closed = true;
             } catch (Exception e) {
                 throw new IOException("Error while closing Serial over LAN instance", e);
             }
 
         }
     }
 
     private boolean isNackForWholeMessage(SolResponseData responseData) {
         return responseData != null
                 && responseData.getAcknowledgeState() == SolAckState.NACK
                 && responseData.getAcceptedCharactersNumber() == 0;
     }
 
     private boolean isNackForMessagePart(SolResponseData responseData, int previousMessageDataLength) {
         return responseData != null
                 && responseData.getAcknowledgeState() == SolAckState.NACK
                 && responseData.getAcceptedCharactersNumber() > 0
                 && responseData.getAcceptedCharactersNumber() < previousMessageDataLength;
     }
 
 }