diff --git a/src/zutil/io/InputStreamCloser.java b/src/zutil/io/InputStreamCloser.java
index b220e47..7b42037 100755
--- a/src/zutil/io/InputStreamCloser.java
+++ b/src/zutil/io/InputStreamCloser.java
@@ -25,38 +25,28 @@
 package zutil.io;
 
 import java.io.Closeable;
+import java.io.FilterInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 
 /**
- * A simple Class that mirrors a InputStream but
- * also has an additional Closeable objects that
- * will be closed when the this object is closed.
+ * A simple Class that mirrors a InputStream but also has additional Closeable objects that
+ * will be closed at the same time as the {@link #close()} method is called.
  *
  * @author Ziver
  */
-public class InputStreamCloser extends InputStream{
-    private Closeable[] c;
-    private InputStream in;
+public class InputStreamCloser extends FilterInputStream {
+    private Closeable[] additionalClosable;
 
-    public InputStreamCloser(InputStream in, Closeable... c) {
-        this.c = c;
-        this.in = in;
+    public InputStreamCloser(InputStream in, Closeable... additionalClosable) {
+        super(in);
+        this.additionalClosable = additionalClosable;
     }
 
     public void close() throws IOException {
-        in.close();
-        for (Closeable stream : c)
+        super.close();
+
+        for (Closeable stream : additionalClosable)
             stream.close();
     }
-
-    // Mirror functions
-    public int read() throws IOException                { return in.read(); }
-    public int read(byte b[]) throws IOException        { return in.read(b); }
-    public int read(byte b[], int off, int len) throws IOException { return in.read(b, off, len); }
-    public long skip(long n) throws IOException         { return in.skip(n); }
-    public int available() throws IOException           { return in.available(); }
-    public synchronized void mark(int readlimit)        { in.mark(readlimit); }
-    public synchronized void reset() throws IOException { in.reset(); }
-    public boolean markSupported()                      { return in.markSupported(); }
 }
\ No newline at end of file
diff --git a/src/zutil/io/PositionalInputStream.java b/src/zutil/io/PositionalInputStream.java
new file mode 100644
index 0000000..204b89f
--- /dev/null
+++ b/src/zutil/io/PositionalInputStream.java
@@ -0,0 +1,82 @@
+package zutil.io;
+
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * A InputStream wrapper that counts the current position in the data stream which equals the amount of data read.
+ */
+public class PositionalInputStream extends FilterInputStream {
+
+    private long pos = 0;
+    private long mark = 0;
+
+
+    /**
+     * @param in the underlying input stream.
+     */
+    protected PositionalInputStream(InputStream in) {
+        super(in);
+    }
+
+
+    /**
+     * @return the current position in the data stream
+     */
+    public synchronized long getPosition() {
+        return pos;
+    }
+
+
+    @Override
+    public int read() throws IOException {
+        int b = super.read();
+
+        synchronized(this) {
+            if (b >= 0) pos += 1;
+        }
+        return b;
+    }
+
+    @Override
+    public int read(byte[] b, int off, int len) throws IOException {
+        int n = super.read(b, off, len);
+
+        synchronized(this) {
+            if (n > 0) pos += n;
+        }
+        return n;
+    }
+
+    @Override
+    public long skip(long skip) throws IOException {
+        long n = super.skip(skip);
+
+        synchronized(this) {
+            if (n > 0) pos += n;
+        }
+        return n;
+    }
+
+    @Override
+    public void mark(int readlimit) {
+        super.mark(readlimit);
+
+        synchronized(this) {
+            mark = pos;
+        }
+    }
+
+    @Override
+    public synchronized void reset() throws IOException {
+        super.reset();
+
+        synchronized(this) {
+            // Only update the position if mark is supported,
+            // as reset succeeds even if mark is not supported.
+            if (markSupported())
+                pos = mark;
+        }
+    }
+}
diff --git a/src/zutil/io/StringInputStream.java b/src/zutil/io/StringInputStream.java
index dd09930..19ba225 100755
--- a/src/zutil/io/StringInputStream.java
+++ b/src/zutil/io/StringInputStream.java
@@ -25,30 +25,30 @@
 package zutil.io;
 
 import java.io.InputStream;
-import java.nio.charset.StandardCharsets;
 
 /**
- * This class saves all the input data in to an StringBuffer
+ * This InputStream uses a string as the data source.
  *
  * @author Ziver
  *
  */
-public class StringInputStream extends InputStream{
-    // The buffer
-    protected StringBuilder buffer;
+public class StringInputStream extends InputStream {
+
+    private StringBuilder buffer = new StringBuilder();
+    private int pos;
+    private int mark;
+
 
     /**
-     * Creates an new instance of this class
+     * Creates a new instance of this class
      */
-    public StringInputStream() {
-        clear();
-    }
+    public StringInputStream() { }
 
     public StringInputStream(String data) {
-        clear();
         add(data);
     }
 
+
     /**
      * Returns an estimate of the number of bytes
      * that can be read (or skipped over) from this
@@ -56,44 +56,37 @@ public class StringInputStream extends InputStream{
      * invocation of a method for this input stream.
      */
     public int available() {
-        return buffer.length();
+        return buffer.length() - pos;
     }
 
 
     /**
      * Reads the next byte of data from the input stream.
      */
-    public int read() {
-        if (buffer.length() == 0)
+    public synchronized int read() {
+        if (available() <= 0)
             return -1;
 
-        int ret = buffer.charAt(0);
-        buffer.deleteCharAt(0);
+        int ret = buffer.charAt(pos);
+        pos++;
         return ret;
     }
 
     /**
-     * Reads some number of bytes from the input stream
-     * and stores them into the buffer array b.
+     * Reads up to len bytes of data from the input stream into an array of bytes.
      */
-    public int read(byte[] b) {
-        return read(b, 0, b.length);
-    }
-
-    /**
-     * Reads up to len bytes of data from the input stream
-     * into an array of bytes.
-     */
-    public int read(byte[] b, int off, int len) {
-        if (buffer.length() == 0)
+    public synchronized int read(byte[] b, int off, int len) {
+        if (available() <= 0)
             return -1;
 
-        if (buffer.length() < len) {
-            len = buffer.length();
+        if (available() < len)
+            len = available();
+
+        for (int i=0; i<len; i++) {
+            b[off + i] = (byte) buffer.charAt(pos);
+            pos++;
         }
-        byte[] btmp = buffer.substring(0, len).getBytes(StandardCharsets.ISO_8859_1);
-        System.arraycopy(btmp, 0, b, off, len);
-        buffer.delete(0, len);
+
         return len;
     }
 
@@ -104,16 +97,12 @@ public class StringInputStream extends InputStream{
      *
      * @param	n		is the amount characters to skip
      */
-    public long skip(long n) {
-        if (buffer.length() < n) {
-            int len = buffer.length();
-            buffer.delete(0, len);
-            return len;
-        }
-        else {
-            buffer.delete(0, (int) n);
-            return n;
-        }
+    public synchronized long skip(long n) {
+        if (available() < n)
+            n = available();
+
+        pos += n;
+        return n;
     }
 
     /**
@@ -121,7 +110,23 @@ public class StringInputStream extends InputStream{
      * reset methods.
      */
     public boolean markSupported() {
-        return false;
+        return true;
+    }
+
+    /**
+     * Set the current position as a sae point that can be returned to with the {@link #reset()} method
+     *
+     * @param readLimit parameter not used.
+     */
+    public synchronized void mark(int readLimit) {
+        mark = pos;
+    }
+
+    /**
+     * Reset the reading position back to the mark point.
+     */
+    public synchronized void reset() {
+        pos = mark;
     }
 
 
@@ -133,8 +138,19 @@ public class StringInputStream extends InputStream{
         clear();
     }
 
-    public void clear() {
+    public synchronized void clear() {
         buffer = new StringBuilder();
+        pos = 0;
+        mark = 0;
+    }
+
+    /**
+     * Clears the part of the String buffer that has already been read.
+     */
+    public synchronized void clearOld() {
+        buffer.delete(0, pos);
+        pos = 0;
+        mark = 0;
     }
 
     public void add(String data) {
diff --git a/src/zutil/io/StringOutputStream.java b/src/zutil/io/StringOutputStream.java
index b6d9a08..2c3ad72 100755
--- a/src/zutil/io/StringOutputStream.java
+++ b/src/zutil/io/StringOutputStream.java
@@ -27,7 +27,7 @@ package zutil.io;
 import java.io.OutputStream;
 
 /**
- * This class saves all the input data in to an StringBuffer
+ * This class saves all the input data into a String
  *
  * @author Ziver
  *
diff --git a/src/zutil/net/dns/packet/FQDNStringSerializer.java b/src/zutil/net/dns/packet/FQDNStringSerializer.java
index 10cad8e..f7b32de 100755
--- a/src/zutil/net/dns/packet/FQDNStringSerializer.java
+++ b/src/zutil/net/dns/packet/FQDNStringSerializer.java
@@ -45,12 +45,13 @@ public class FQDNStringSerializer implements BinaryFieldSerializer<String> {
                 str.append('.');
 
             if ((c & 0b1100_0000) == 0b1100_0000) {
-                // This a pointer
+                // This a offset pointer to the String data
                 int offset = (c & 0b0011_1111) << 8;
                 offset |= in.read() & 0b1111_1111;
                 str.append(offset);
+                break; // PTR is always the last part of the FQDN
             } else {
-                // Normal String
+                // Normal String data
                 for (int i = 0; i < c; ++i) {
                     str.append((char) in.read());
                 }
diff --git a/test/zutil/io/PositionalInputStreamTest.java b/test/zutil/io/PositionalInputStreamTest.java
new file mode 100644
index 0000000..798202f
--- /dev/null
+++ b/test/zutil/io/PositionalInputStreamTest.java
@@ -0,0 +1,75 @@
+package zutil.io;
+
+import org.junit.Test;
+
+import java.io.IOException;
+
+import static org.junit.Assert.assertEquals;
+
+
+public class PositionalInputStreamTest {
+
+    @Test
+    public void read() throws IOException {
+        PositionalInputStream in = new PositionalInputStream(new StringInputStream("hello"));
+
+        assertEquals(0, in.getPosition());
+        assertEquals('h', (char) in.read());
+        assertEquals(1, in.getPosition());
+        assertEquals('e', (char) in.read());
+        assertEquals(2, in.getPosition());
+        assertEquals('l', (char) in.read());
+        assertEquals(3, in.getPosition());
+        assertEquals('l', (char) in.read());
+        assertEquals(4, in.getPosition());
+        assertEquals('o', (char) in.read());
+        assertEquals(5, in.getPosition());
+        assertEquals(-1, in.read());
+        assertEquals(5, in.getPosition());
+        assertEquals(-1, in.read());
+        assertEquals(5, in.getPosition());
+    }
+
+    @Test
+    public void readArray() throws IOException {
+        PositionalInputStream in = new PositionalInputStream(new StringInputStream("hello world"));
+
+        byte[] buffer = new byte[20];
+        assertEquals(5, in.read(buffer, 0, 5));
+        assertEquals("hello", new String(buffer, 0, 5));
+        assertEquals(5, in.getPosition());
+
+        assertEquals(' ', (char) in.read());
+        assertEquals(6, in.getPosition());
+
+        assertEquals(5, in.read(buffer));
+        assertEquals("world", new String(buffer, 0, 5));
+        assertEquals(11, in.getPosition());
+
+        assertEquals(-1, in.read());
+        assertEquals(11, in.getPosition());
+    }
+
+    @Test
+    public void skip() throws IOException {
+        PositionalInputStream in = new PositionalInputStream(new StringInputStream("hello world"));
+
+        assertEquals(5, in.skip(5));
+        assertEquals(5, in.getPosition());
+        assertEquals(6, in.skip(20));
+        assertEquals(11, in.getPosition());
+    }
+
+    @Test
+    public void mark() throws IOException {
+        PositionalInputStream in = new PositionalInputStream(new StringInputStream("hello world"));
+
+        in.mark(20);
+        assertEquals(6, in.skip(6));
+        assertEquals(6, in.getPosition());
+        in.reset();
+        assertEquals(0, in.getPosition());
+        assertEquals('h', (char) in.read());
+        assertEquals(1, in.getPosition());
+    }
+}
\ No newline at end of file
diff --git a/test/zutil/io/StringInputStreamTest.java b/test/zutil/io/StringInputStreamTest.java
new file mode 100644
index 0000000..42766e3
--- /dev/null
+++ b/test/zutil/io/StringInputStreamTest.java
@@ -0,0 +1,58 @@
+package zutil.io;
+
+import org.junit.Test;
+
+import java.io.IOException;
+
+import static org.junit.Assert.assertEquals;
+
+
+public class StringInputStreamTest {
+
+    @Test
+    public void read() throws IOException {
+        StringInputStream in = new StringInputStream("hello");
+
+        assertEquals('h', (char) in.read());
+        assertEquals('e', (char) in.read());
+        assertEquals('l', (char) in.read());
+        assertEquals('l', (char) in.read());
+        assertEquals('o', (char) in.read());
+        assertEquals(-1, in.read());
+        assertEquals(-1, in.read());
+    }
+
+    @Test
+    public void readArray() throws IOException {
+        StringInputStream in = new StringInputStream("hello world");
+
+        byte[] buffer = new byte[20];
+        assertEquals(5, in.read(buffer, 0, 5));
+        assertEquals("hello", new String(buffer, 0, 5));
+
+        assertEquals(' ', (char) in.read());
+
+        assertEquals(5, in.read(buffer));
+        assertEquals("world", new String(buffer, 0, 5));
+
+        assertEquals(-1, in.read());
+    }
+
+    @Test
+    public void skip() {
+        StringInputStream in = new StringInputStream("hello world");
+
+        assertEquals(5, in.skip(5));
+        assertEquals(6, in.skip(20));
+    }
+
+    @Test
+    public void mark() throws IOException {
+        StringInputStream in = new StringInputStream("hello world");
+
+        in.mark(20);
+        assertEquals(6, in.skip(6));
+        in.reset();
+        assertEquals('h', (char) in.read());
+    }
+}
\ No newline at end of file