1 files changed, 133 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/tls/DTLSReassembler.java b/core/src/main/java/org/spongycastle/crypto/tls/DTLSReassembler.java
new file mode 100644
index 00000000..810d6979
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/crypto/tls/DTLSReassembler.java
@@ -0,0 +1,133 @@
+package org.spongycastle.crypto.tls;
+
+import java.util.Vector;
+
+class DTLSReassembler
+{
+    private final short msg_type;
+    private final byte[] body;
+
+    private Vector missing = new Vector();
+
+    DTLSReassembler(short msg_type, int length)
+    {
+        this.msg_type = msg_type;
+        this.body = new byte[length];
+        this.missing.addElement(new Range(0, length));
+    }
+
+    short getType()
+    {
+        return msg_type;
+    }
+
+    byte[] getBodyIfComplete()
+    {
+        return missing.isEmpty() ? body : null;
+    }
+
+    void contributeFragment(short msg_type, int length, byte[] buf, int off, int fragment_offset,
+        int fragment_length)
+    {
+        int fragment_end = fragment_offset + fragment_length;
+
+        if (this.msg_type != msg_type || this.body.length != length || fragment_end > length)
+        {
+            return;
+        }
+
+        if (fragment_length == 0)
+        {
+            // NOTE: Empty messages still require an empty fragment to complete it
+            if (fragment_offset == 0 && !missing.isEmpty())
+            {
+                Range firstRange = (Range)missing.firstElement();
+                if (firstRange.getEnd() == 0)
+                {
+                    missing.removeElementAt(0);
+                }
+            }
+            return;
+        }
+
+        for (int i = 0; i < missing.size(); ++i)
+        {
+            Range range = (Range)missing.elementAt(i);
+            if (range.getStart() >= fragment_end)
+            {
+                break;
+            }
+            if (range.getEnd() > fragment_offset)
+            {
+
+                int copyStart = Math.max(range.getStart(), fragment_offset);
+                int copyEnd = Math.min(range.getEnd(), fragment_end);
+                int copyLength = copyEnd - copyStart;
+
+                System.arraycopy(buf, off + copyStart - fragment_offset, body, copyStart,
+                    copyLength);
+
+                if (copyStart == range.getStart())
+                {
+                    if (copyEnd == range.getEnd())
+                    {
+                        missing.removeElementAt(i--);
+                    }
+                    else
+                    {
+                        range.setStart(copyEnd);
+                    }
+                }
+                else
+                {
+                    if (copyEnd == range.getEnd())
+                    {
+                        range.setEnd(copyStart);
+                    }
+                    else
+                    {
+                        missing.insertElementAt(new Range(copyEnd, range.getEnd()), ++i);
+                        range.setEnd(copyStart);
+                    }
+                }
+            }
+        }
+    }
+
+    void reset()
+    {
+        this.missing.removeAllElements();
+        this.missing.addElement(new Range(0, body.length));
+    }
+
+    private static class Range
+    {
+        private int start, end;
+
+        Range(int start, int end)
+        {
+            this.start = start;
+            this.end = end;
+        }
+
+        public int getStart()
+        {
+            return start;
+        }
+
+        public void setStart(int start)
+        {
+            this.start = start;
+        }
+
+        public int getEnd()
+        {
+            return end;
+        }
+
+        public void setEnd(int end)
+        {
+            this.end = end;
+        }
+    }
+}