#2473 P25P1 bad frequency bands messages contaminating channel frequency calculation map (#2474)

Co-authored-by: denny <dennis.sheirer@gmail.com>

src/main/java/io/github/dsheirer/module/decode/p25/phase1/P25P1MessageProcessor.java

@@ -306,10 +306,8 @@ public class P25P1MessageProcessor implements Listener<IMessage>
     private void processForFrequencyBands(AbstractMessage message)
     {
         //Insert frequency band identifier update messages into channel-type messages */
-        if(message instanceof IFrequencyBandReceiver)
+        if(message instanceof IFrequencyBandReceiver receiver)
         {
-            IFrequencyBandReceiver receiver = (IFrequencyBandReceiver)message;
-
             List<IBandChannelDescriptor> channels = receiver.getChannels();
 
             for(IBandChannelDescriptor channel : channels)
@@ -327,10 +325,9 @@ public class P25P1MessageProcessor implements Listener<IMessage>
         }
 
         //Store band identifiers so that they can be injected into channel type messages
-        if(message instanceof IFrequencyBand)
+        if(message instanceof IFrequencyBand band && band.isValid())
         {
-            IFrequencyBand bandIdentifier = (IFrequencyBand)message;
-            mFrequencyBandMap.put(bandIdentifier.getIdentifier(), bandIdentifier);
+            mFrequencyBandMap.put(band.getIdentifier(), band);
         }
     }
 

src/main/java/io/github/dsheirer/module/decode/p25/phase1/message/IFrequencyBand.java

@@ -19,43 +19,49 @@
  */
 package io.github.dsheirer.module.decode.p25.phase1.message;
 
+/**
+ * P25 frequency band provider interface.
+ */
 public interface IFrequencyBand
 {
+    /**
+     * Indicates if the band is valid and passes CRC checks.
+     */
+    boolean isValid();
     /**
      * (Band) Identifier
      */
-    public abstract int getIdentifier();
+    int getIdentifier();
 
     /**
      * Channel spacing in hertz
      */
-    public abstract long getChannelSpacing();
+    long getChannelSpacing();
 
     /**
      * Base frequency in hertz
      */
-    public abstract long getBaseFrequency();
-
+    long getBaseFrequency();
 
     /**
      * Channel bandwidth in hertz
      */
-    public abstract int getBandwidth();
+    int getBandwidth();
 
     /**
      * Transmit offset in hertz
      */
-    public abstract long getTransmitOffset();
+    long getTransmitOffset();
 
     /**
      * Downlink (tower to mobile) Frequency for the specified channel
      */
-    public abstract long getDownlinkFrequency(int channelNumber);
+    long getDownlinkFrequency(int channelNumber);
 
     /**
      * Uplink (mobile to tower) Frequency for the specified channel
      */
-    public abstract long getUplinkFrequency(int channelNumber);
+    long getUplinkFrequency(int channelNumber);
 
     /**
      * Indicates if this band is an FDMA (false) or TDMA (true) band

src/main/java/io/github/dsheirer/module/decode/p25/phase1/message/P25FrequencyBand.java

@@ -34,6 +34,12 @@ public class P25FrequencyBand implements IFrequencyBand
         mTimeslotCount = timeslotCount;
     }
 
+    @Override
+    public boolean isValid()
+    {
+        return true;
+    }
+
     @Override
     public int getIdentifier()
     {

src/main/java/io/github/dsheirer/module/decode/p25/phase2/message/mac/structure/FrequencyBandUpdate.java

@@ -50,6 +50,13 @@ public class FrequencyBandUpdate extends MacStructure implements IFrequencyBand
         super(message, offset);
     }
 
+    @Override
+    public boolean isValid()
+    {
+        //Note: this message is only created when the parent passes CRC, therefore it should be valid.
+        return true;
+    }
+
     /**
      * Textual representation of this message
      */

src/main/java/io/github/dsheirer/module/decode/p25/phase2/message/mac/structure/FrequencyBandUpdateTDMAAbbreviated.java

@@ -53,6 +53,13 @@ public class FrequencyBandUpdateTDMAAbbreviated extends MacStructure implements
         super(message, offset);
     }
 
+    @Override
+    public boolean isValid()
+    {
+        //Note: this message is only created when the parent passes CRC, therefore it should be valid.
+        return true;
+    }
+
     /**
      * Textual representation of this message
      */

src/main/java/io/github/dsheirer/module/decode/p25/phase2/message/mac/structure/FrequencyBandUpdateTDMAExtended.java

@@ -59,6 +59,13 @@ public class FrequencyBandUpdateTDMAExtended extends MacStructure implements IFr
         super(message, offset);
     }
 
+    @Override
+    public boolean isValid()
+    {
+        //Note: this message is only created when the parent passes CRC, therefore it should be valid.
+        return true;
+    }
+
     /**
      * Textual representation of this message
      */

src/main/java/io/github/dsheirer/module/decode/p25/phase2/message/mac/structure/FrequencyBandUpdateVUHF.java

@@ -50,6 +50,13 @@ public class FrequencyBandUpdateVUHF extends MacStructure implements IFrequencyB
         super(message, offset);
     }
 
+    @Override
+    public boolean isValid()
+    {
+        //Note: this message is only created when the parent passes CRC, therefore it should be valid.
+        return true;
+    }
+
     /**
      * Textual representation of this message
      */