[pjlink] Null characters fix (openhab#7462)

* use MessageFormat where applicable
* remove null characters from response

see openhab#6725

Signed-off-by: Nils Schnabel <github@to.nilsschnabel.de>
Signed-off-by: Eugen Freiter <freiter@gmx.de>

bundles/org.openhab.binding.pjlinkdevice/src/main/java/org/openhab/binding/pjlinkdevice/internal/device/PJLinkDevice.java

@@ -22,6 +22,7 @@
 import java.net.Socket;
 import java.net.SocketAddress;
 import java.net.SocketTimeoutException;
+import java.text.MessageFormat;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Arrays;
@@ -206,6 +207,11 @@ public void addPrefixToNextCommand(String cmd) throws IOException, Authenticatio
  this.prefixForNextCommand = cmd;
  }
 
+ public static String preprocessResponse(String response) {
+ // some devices send leading zero bytes, see https://github.com/openhab/openhab-addons/issues/6725
+ return response.replaceAll("^\0*|\0*$", "");
+ }
+
  public synchronized String execute(String command) throws IOException, AuthenticationException, ResponseException {
  String fullCommand = this.prefixForNextCommand + command;
  this.prefixForNextCommand = "";
@@ -227,18 +233,20 @@ public synchronized String execute(String command) throws IOException, Authentic
  }
 
  String response = null;
- while ((response = getReader().readLine()) != null && response.isEmpty()) {
+ while ((response = getReader().readLine()) != null && preprocessResponse(response).isEmpty()) {
  logger.debug("Got empty string response for request '{}' from {}, waiting for another line", response,
  fullCommand.replaceAll("\r", "\\\\r"));
  }
  if (response == null) {
- throw new ResponseException("Response to request '" + fullCommand.replaceAll("\r", "\\\\r") + "' was null");
+ throw new ResponseException(MessageFormat.format("Response to request ''{0}'' was null",
+ fullCommand.replaceAll("\r", "\\\\r")));
  }
+
  if (logger.isDebugEnabled()) {
  logger.debug("Got response '{}' ({}) for request '{}' from {}", response,
  Arrays.toString(response.getBytes()), fullCommand.replaceAll("\r", "\\\\r"), ipAddress);
  }
- return response;
+ return preprocessResponse(response);
  }
 
  public void checkAvailability() throws IOException, AuthenticationException, ResponseException {