diff --git a/rak/error_number.h b/rak/error_number.h
index d2964b0f..99c7ba4d 100644
--- a/rak/error_number.h
+++ b/rak/error_number.h
@@ -47,6 +47,8 @@ public:
   error_number() : m_errno(0) {}
   error_number(int e) : m_errno(e) {}
 
+  bool                is_valid() const             { return m_errno != 0; }
+
   int                 value() const                { return m_errno; }
   const char*         c_str() const                { return strerror(m_errno); }
 
diff --git a/rak/ranges.h b/rak/ranges.h
new file mode 100644
index 00000000..87c19074
--- /dev/null
+++ b/rak/ranges.h
@@ -0,0 +1,132 @@
+// libTorrent - BitTorrent library
+// Copyright (C) 2005, Jari Sundell
+//
+// This program 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 program 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 program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//
+// In addition, as a special exception, the copyright holders give
+// permission to link the code of portions of this program with the
+// OpenSSL library under certain conditions as described in each
+// individual source file, and distribute linked combinations
+// including the two.
+//
+// You must obey the GNU General Public License in all respects for
+// all of the code used other than OpenSSL.  If you modify file(s)
+// with this exception, you may extend this exception to your version
+// of the file(s), but you are not obligated to do so.  If you do not
+// wish to do so, delete this exception statement from your version.
+// If you delete this exception statement from all source files in the
+// program, then also delete it here.
+//
+// Contact:  Jari Sundell <jaris@ifi.uio.no>
+//
+//           Skomakerveien 33
+//           3185 Skoppum, NORWAY
+
+#ifndef RAK_RANGES_H
+#define RAK_RANGES_H
+
+#include <algorithm>
+#include <vector>
+#include <rak/functional.h>
+
+namespace rak {
+
+template <typename Type>
+class ranges : private std::vector<std::pair<Type, Type> > {
+public:
+  typedef std::vector<std::pair<Type, Type> > Base;
+  typedef typename Base::value_type           value_type;
+  typedef typename Base::reference            reference;
+  typedef typename Base::iterator             iterator;
+  typedef typename Base::const_iterator       const_iterator;
+  typedef typename Base::reverse_iterator     reverse_iterator;
+
+  using Base::clear;
+  using Base::size;
+  using Base::begin;
+  using Base::end;
+  using Base::rbegin;
+  using Base::rend;
+
+  void                insert(Type first, Type last) { insert(std::make_pair(first, last)); }
+//   void                erase(Type first, Type last)  { erase(std::make_pair(first, last)); }
+
+  void                insert(value_type r);
+//   void                erase(value_type r);
+
+  // Find the first ranges that has an end greater than index.
+  inline iterator     find(Type index);
+
+  // Use find with no closest match.
+  inline bool         has(Type index);
+
+private:
+  inline void         unify(iterator itr);
+};
+
+template <typename Type>
+void
+ranges<Type>::insert(value_type r) {
+  if (r.first >= r.second)
+    return;
+
+  iterator first = std::find_if(begin(), end(), rak::less_equal(r.first, rak::mem_ptr_ref(&value_type::second)));
+
+  if (first == end() || r.second < first->first) {
+    // The new range is before the first, after the last or between
+    // two ranges.
+    Base::insert(first, r);
+    return;
+  }
+  
+  first->first = std::min(r.first, first->first);
+  first->second = std::max(r.second, first->second);
+
+  unify(first);
+}
+
+// template <typename Type>
+// void
+// ranges<Type>::erase(value_type r) {
+// }
+
+// Find the first ranges that has an end greater than index.
+template <typename Type>
+inline typename ranges<Type>::iterator
+ranges<Type>::find(Type index) {
+  return std::find_if(begin(), end(), rak::less(index, rak::mem_ptr_ref(&value_type::second)));
+}
+
+// Use find with no closest match.
+template <typename Type>
+inline bool
+ranges<Type>::has(Type index) {
+  const_iterator itr = find(index);
+
+  return itr != end() && index >= itr->first;
+}
+
+template <typename Type>
+inline void
+ranges<Type>::unify(iterator first) {
+  iterator last = std::find_if((first + 1), end(), rak::less(first->second, rak::mem_ptr_ref(&value_type::first)));
+
+  first->second = std::max(first->second, (last - 1)->second);
+  Base::erase((first + 1), last);
+}
+
+}
+
+#endif
diff --git a/src/core/curl_get.cc b/src/core/curl_get.cc
index de18a3b6..5f6750ea 100644
--- a/src/core/curl_get.cc
+++ b/src/core/curl_get.cc
@@ -141,6 +141,10 @@ CurlGet::perform(CURLMsg* msg) {
     m_signalDone.emit();
   else
     m_signalFailed.emit(curl_easy_strerror(msg->data.result));
+
+  if (m_handle != NULL)
+    throw std::logic_error("CurlGet::perform finished but the object wasn't closed.");
+
 }
 
 }
diff --git a/src/core/download_list.h b/src/core/download_list.h
index 1b0d54c9..3c770c24 100644
--- a/src/core/download_list.h
+++ b/src/core/download_list.h
@@ -46,6 +46,10 @@ namespace core {
 
 class Download;
 
+// Container for all downloads. Add slots to the slot maps to cause
+// some action to be taken when the torrent changes states. Don't
+// change the states from outside of core.
+
 class DownloadList : private std::list<Download*> {
 public:
   typedef std::list<Download*> Base;