diff --git a/common/rdr/ZlibInStream.cxx b/common/rdr/ZlibInStream.cxx
new file mode 100644
index 0000000..6f3a7d0
--- /dev/null
+++ b/common/rdr/ZlibInStream.cxx
@@ -0,0 +1,125 @@
+/* Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
+ * 
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+#include <rdr/ZlibInStream.h>
+#include <rdr/Exception.h>
+#include <zlib.h>
+
+using namespace rdr;
+
+enum { DEFAULT_BUF_SIZE = 16384 };
+
+ZlibInStream::ZlibInStream(int bufSize_)
+  : underlying(0), bufSize(bufSize_ ? bufSize_ : DEFAULT_BUF_SIZE), offset(0),
+    bytesIn(0)
+{
+  zs = new z_stream;
+  zs->zalloc    = Z_NULL;
+  zs->zfree     = Z_NULL;
+  zs->opaque    = Z_NULL;
+  zs->next_in   = Z_NULL;
+  zs->avail_in  = 0;
+  if (inflateInit(zs) != Z_OK) {
+    delete zs;
+    throw Exception("ZlibInStream: inflateInit failed");
+  }
+  ptr = end = start = new U8[bufSize];
+}
+
+ZlibInStream::~ZlibInStream()
+{
+  delete [] start;
+  inflateEnd(zs);
+  delete zs;
+}
+
+void ZlibInStream::setUnderlying(InStream* is, int bytesIn_)
+{
+  underlying = is;
+  bytesIn = bytesIn_;
+  ptr = end = start;
+}
+
+int ZlibInStream::pos()
+{
+  return offset + ptr - start;
+}
+
+void ZlibInStream::reset()
+{
+  ptr = end = start;
+  if (!underlying) return;
+
+  while (bytesIn > 0) {
+    decompress(true);
+    end = start; // throw away any data
+  }
+  underlying = 0;
+}
+
+int ZlibInStream::overrun(int itemSize, int nItems, bool wait)
+{
+  if (itemSize > bufSize)
+    throw Exception("ZlibInStream overrun: max itemSize exceeded");
+  if (!underlying)
+    throw Exception("ZlibInStream overrun: no underlying stream");
+
+  if (end - ptr != 0)
+    memmove(start, ptr, end - ptr);
+
+  offset += ptr - start;
+  end -= ptr - start;
+  ptr = start;
+
+  while (end - ptr < itemSize) {
+    if (!decompress(wait))
+      return 0;
+  }
+
+  if (itemSize * nItems > end - ptr)
+    nItems = (end - ptr) / itemSize;
+
+  return nItems;
+}
+
+// decompress() calls the decompressor once.  Note that this won't necessarily
+// generate any output data - it may just consume some input data.  Returns
+// false if wait is false and we would block on the underlying stream.
+
+bool ZlibInStream::decompress(bool wait)
+{
+  zs->next_out = (U8*)end;
+  zs->avail_out = start + bufSize - end;
+
+  int n = underlying->check(1, 1, wait);
+  if (n == 0) return false;
+  zs->next_in = (U8*)underlying->getptr();
+  zs->avail_in = underlying->getend() - underlying->getptr();
+  if ((int)zs->avail_in > bytesIn)
+    zs->avail_in = bytesIn;
+
+  int rc = inflate(zs, Z_SYNC_FLUSH);
+  if (rc != Z_OK) {
+    throw Exception("ZlibInStream: inflate failed");
+  }
+
+  bytesIn -= zs->next_in - underlying->getptr();
+  end = zs->next_out;
+  underlying->setptr(zs->next_in);
+  return true;
+}