Fixed DNS FQDN parsing

src/zutil/io/PositionalInputStream.java

@@ -16,7 +16,7 @@ public class PositionalInputStream extends FilterInputStream {
     /**
      * @param in the underlying input stream.
      */
-    protected PositionalInputStream(InputStream in) {
+    public PositionalInputStream(InputStream in) {
         super(in);
     }
 
@@ -60,8 +60,8 @@ public class PositionalInputStream extends FilterInputStream {
     }
 
     @Override
-    public void mark(int readlimit) {
-        super.mark(readlimit);
+    public void mark(int readLimit) {
+        super.mark(readLimit);
 
         synchronized(this) {
             mark = pos;

src/zutil/net/dns/MulticastDnsClient.java

@@ -78,7 +78,6 @@ public class MulticastDnsClient extends ThreadedUDPNetwork implements ThreadedUD
         int id = 0; // Needs to be zero when doing multicast
         activeProbes.add(id);
         ByteArrayOutputStream buffer = new ByteArrayOutputStream();
-        BinaryStructOutputStream out = new BinaryStructOutputStream(buffer);
 
         DnsPacket dnsPacket = new DnsPacket();
         dnsPacket.getHeader().id = id;
@@ -87,7 +86,7 @@ public class MulticastDnsClient extends ThreadedUDPNetwork implements ThreadedUD
                 domain,
                 DnsConstants.TYPE.SRV,
                 DnsConstants.CLASS.IN));
-        dnsPacket.write(out);
+        dnsPacket.write(buffer);
 
         DatagramPacket udpPacket = new DatagramPacket(
                 buffer.toByteArray(), buffer.size(),
@@ -106,8 +105,7 @@ public class MulticastDnsClient extends ThreadedUDPNetwork implements ThreadedUD
         try {
             ByteArrayInputStream buffer = new ByteArrayInputStream(packet.getData(),
                     packet.getOffset(), packet.getLength());
-            BinaryStructInputStream in = new BinaryStructInputStream(buffer);
-            DnsPacket dnsPacket = DnsPacket.read(in);
+            DnsPacket dnsPacket = DnsPacket.read(buffer);
 
             //System.out.println("Received:\n" +ByteUtil.toFormattedString(packet.getData(), packet.getOffset(), packet.getLength()));
             MultiPrintStream.out.dump(dnsPacket,3);

src/zutil/net/dns/MulticastDnsServer.java

@@ -112,8 +112,7 @@ public class MulticastDnsServer extends ThreadedUDPNetwork implements ThreadedUD
         try {
             ByteArrayInputStream buffer = new ByteArrayInputStream(packet.getData(),
                     packet.getOffset(), packet.getLength());
-            BinaryStructInputStream in = new BinaryStructInputStream(buffer);
-            DnsPacket dnsPacket = DnsPacket.read(in);
+            DnsPacket dnsPacket = DnsPacket.read(buffer);
 
             // Just handle queries and no responses
             if (! dnsPacket.getHeader().flagQueryResponse) {
@@ -121,9 +120,8 @@ public class MulticastDnsServer extends ThreadedUDPNetwork implements ThreadedUD
 
                 if (response != null) {
                     ByteArrayOutputStream outBuffer = new ByteArrayOutputStream();
-                    BinaryStructOutputStream out = new BinaryStructOutputStream(outBuffer);
-                    response.write(out);
-                    out.close();
+                    response.write(outBuffer);
+                    outBuffer.close();
 
                     DatagramPacket outPacket = new DatagramPacket(
                             outBuffer.toByteArray(), outBuffer.size(),

src/zutil/net/dns/packet/DnsPacket.java

@@ -24,10 +24,13 @@
 
 package zutil.net.dns.packet;
 
+import zutil.io.PositionalInputStream;
 import zutil.parser.binary.BinaryStructInputStream;
 import zutil.parser.binary.BinaryStructOutputStream;
 
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -94,7 +97,9 @@ public class DnsPacket {
     }
 
 
-    public static DnsPacket read(BinaryStructInputStream structIn) throws IOException {
+    public static DnsPacket read(InputStream in) throws IOException {
+        BinaryStructInputStream structIn = new BinaryStructInputStream(new PositionalInputStream(in));
+
         DnsPacket packet = new DnsPacket();
         structIn.read(packet.header);
 
@@ -116,7 +121,9 @@ public class DnsPacket {
         }
     }
 
-    public void write(BinaryStructOutputStream structOut) throws IOException {
+    public void write(OutputStream out) throws IOException {
+        BinaryStructOutputStream structOut = new BinaryStructOutputStream(out);
+
         structOut.write(header);
 
         for (DnsPacketQuestion question : questions)

src/zutil/net/dns/packet/FQDNStringSerializer.java

@@ -24,40 +24,64 @@
 
 package zutil.net.dns.packet;
 
+import zutil.io.PositionalInputStream;
 import zutil.parser.binary.BinaryFieldData;
 import zutil.parser.binary.BinaryFieldSerializer;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.util.HashMap;
 
 /**
  * A serializer class that can read and write a DNS FQDN in binary format.
  */
 public class FQDNStringSerializer implements BinaryFieldSerializer<String> {
+    private HashMap<Integer, String> stringCache = new HashMap<>();
+
 
     public String read(InputStream in, BinaryFieldData field) throws IOException {
-        StringBuilder str = new StringBuilder();
+        StringBuilder buffer = new StringBuilder();
+        int pos = (int) ((PositionalInputStream) in).getPosition();
         int c;
 
         while ((c=in.read()) > 0) {
-            if (str.length() > 0) // Don't add dot to first loop
-                str.append('.');
+            if (buffer.length() > 0) // Don't add dot to first loop
+                buffer.append('.');
 
             if ((c & 0b1100_0000) == 0b1100_0000) {
-                // This a offset pointer to the String data
+                // This is an offset pointer to the String data
                 int offset = (c & 0b0011_1111) << 8;
                 offset |= in.read() & 0b1111_1111;
-                str.append(offset);
+
+                if (stringCache.containsKey(offset))
+                    buffer.append(stringCache.get(offset));
+                else
+                    buffer.append('<').append(offset).append('>');
                 break; // PTR is always the last part of the FQDN
             } else {
-                // Normal String data
+                // Read normal String data
                 for (int i = 0; i < c; ++i) {
-                    str.append((char) in.read());
+                    buffer.append((char) in.read());
                 }
             }
         }
-        return str.toString();
+
+        String output = buffer.toString();
+
+        // Populate cache
+        if (in instanceof PositionalInputStream) {
+            stringCache.put(pos, output);
+            for (int index = 0; index >= 0;) {
+                index = buffer.indexOf(".", index);
+                if (index >= 0) {
+                    ++index;
+                    stringCache.put(pos + index, buffer.substring(index));
+                }
+            }
+        }
+
+        return output;
     }
 
     public void write(OutputStream out, String domain, BinaryFieldData field) throws IOException {
@@ -70,5 +94,4 @@ public class FQDNStringSerializer implements BinaryFieldSerializer<String> {
         }
         out.write(0);
     }
-
 }

src/zutil/parser/binary/BinaryFieldSerializer.java

@@ -29,15 +29,13 @@ import java.io.InputStream;
 import java.io.OutputStream;
 
 /**
- * An Interface where custom field parser and writer can be implemented.
+ * An Interface defining a custom field parser and writer.
  * <p></p>
- * One instance of the serializer and will have the scope of the methods
- * {@link BinaryStructInputStream#read(BinaryStruct)} and {@link BinaryStructOutputStream#write(BinaryStruct)}
- * where as it will be deallocated after the methods have returned.
+ * One singleton instance of the serializer will be instantiated for the lifetime of the
+ * {@link BinaryStructInputStream} and {@link BinaryStructOutputStream} objects.
  * <p></p>
  * NOTE: Partial octet serializing not supported.
  *
- * Created by Ziver on 2016-04-11.
  */
 public interface BinaryFieldSerializer<T> {
 

src/zutil/parser/binary/BinaryStructInputStream.java

@@ -35,7 +35,7 @@ import java.util.Map;
 
 /**
  * A stream class that parses a byte stream into binary struct objects.
- * <p><p/>
+ * <p></p>
  * Limitations:<br>
  *  - Does not support sub binary objects.<br>
  *
@@ -47,6 +47,9 @@ public class BinaryStructInputStream {
     private byte data;
     private int dataBitIndex = -1;
 
+    private Map<Class, BinaryFieldSerializer> serializerCache = new HashMap<>();
+
+
     public BinaryStructInputStream(InputStream in) {
         this.in = in;
     }
@@ -78,7 +81,6 @@ public class BinaryStructInputStream {
      */
     public int read(BinaryStruct struct) throws IOException {
         List<BinaryFieldData> structDataList = BinaryFieldData.getStructFieldList(struct.getClass());
-        Map<Class, BinaryFieldSerializer> serializerCache = new HashMap<>();
 
         int totalReadLength = 0;
         for (BinaryFieldData field : structDataList) {

src/zutil/parser/binary/BinaryStructOutputStream.java

@@ -36,7 +36,7 @@ import java.util.Map;
 
 /**
  * A stream class that generates a byte stream from a binary struct objects.
- * <p><p/>
+ * <p></p>
  * Limitations:<br>
  *  - Does not support sub binary objects.<br>
  *
@@ -48,6 +48,8 @@ public class BinaryStructOutputStream {
     private byte rest;
     private int restBitLength; // length from Most Significant Bit
 
+    private Map<Class, BinaryFieldSerializer> serializerCache = new HashMap<>();
+
 
     public BinaryStructOutputStream(OutputStream out) {
         this.out = out;
@@ -88,7 +90,6 @@ public class BinaryStructOutputStream {
      */
     public void write(BinaryStruct struct) throws IOException {
         List<BinaryFieldData> structDataList = BinaryFieldData.getStructFieldList(struct.getClass());
-        Map<Class, BinaryFieldSerializer> serializerCache = new HashMap<>();
 
         for (BinaryFieldData field : structDataList) {
             if (field.hasSerializer()) {