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diff --git a/ext/asio/detail/consuming_buffers.hpp b/ext/asio/detail/consuming_buffers.hpp
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+++ b/ext/asio/detail/consuming_buffers.hpp
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+//
+// consuming_buffers.hpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2010 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ASIO_DETAIL_CONSUMING_BUFFERS_HPP
+#define ASIO_DETAIL_CONSUMING_BUFFERS_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/push_options.hpp"
+
+#include "asio/detail/push_options.hpp"
+#include <algorithm>
+#include <cstddef>
+#include <boost/config.hpp>
+#include <boost/iterator.hpp>
+#include <boost/limits.hpp>
+#include "asio/detail/pop_options.hpp"
+
+#include "asio/buffer.hpp"
+
+namespace asio {
+namespace detail {
+
+// A proxy iterator for a sub-range in a list of buffers.
+template <typename Buffer, typename Buffer_Iterator>
+class consuming_buffers_iterator
+  : public boost::iterator<std::forward_iterator_tag, const Buffer>
+{
+public:
+  // Default constructor creates an end iterator.
+  consuming_buffers_iterator()
+    : at_end_(true)
+  {
+  }
+
+  // Construct with a buffer for the first entry and an iterator
+  // range for the remaining entries.
+  consuming_buffers_iterator(bool at_end, const Buffer& first,
+      Buffer_Iterator begin_remainder, Buffer_Iterator end_remainder,
+      std::size_t max_size)
+    : at_end_(max_size > 0 ? at_end : true),
+      first_(buffer(first, max_size)),
+      begin_remainder_(begin_remainder),
+      end_remainder_(end_remainder),
+      offset_(0),
+      max_size_(max_size)
+  {
+  }
+
+  // Dereference an iterator.
+  const Buffer& operator*() const
+  {
+    return dereference();
+  }
+
+  // Dereference an iterator.
+  const Buffer* operator->() const
+  {
+    return &dereference();
+  }
+
+  // Increment operator (prefix).
+  consuming_buffers_iterator& operator++()
+  {
+    increment();
+    return *this;
+  }
+
+  // Increment operator (postfix).
+  consuming_buffers_iterator operator++(int)
+  {
+    consuming_buffers_iterator tmp(*this);
+    ++*this;
+    return tmp;
+  }
+
+  // Test two iterators for equality.
+  friend bool operator==(const consuming_buffers_iterator& a,
+      const consuming_buffers_iterator& b)
+  {
+    return a.equal(b);
+  }
+
+  // Test two iterators for inequality.
+  friend bool operator!=(const consuming_buffers_iterator& a,
+      const consuming_buffers_iterator& b)
+  {
+    return !a.equal(b);
+  }
+
+private:
+  void increment()
+  {
+    if (!at_end_)
+    {
+      if (begin_remainder_ == end_remainder_
+          || offset_ + buffer_size(first_) >= max_size_)
+      {
+        at_end_ = true;
+      }
+      else
+      {
+        offset_ += buffer_size(first_);
+        first_ = buffer(*begin_remainder_++, max_size_ - offset_);
+      }
+    }
+  }
+
+  bool equal(const consuming_buffers_iterator& other) const
+  {
+    if (at_end_ && other.at_end_)
+      return true;
+    return !at_end_ && !other.at_end_
+      && buffer_cast<const void*>(first_)
+        == buffer_cast<const void*>(other.first_)
+      && buffer_size(first_) == buffer_size(other.first_)
+      && begin_remainder_ == other.begin_remainder_
+      && end_remainder_ == other.end_remainder_;
+  }
+
+  const Buffer& dereference() const
+  {
+    return first_;
+  }
+
+  bool at_end_;
+  Buffer first_;
+  Buffer_Iterator begin_remainder_;
+  Buffer_Iterator end_remainder_;
+  std::size_t offset_;
+  std::size_t max_size_;
+};
+
+// A proxy for a sub-range in a list of buffers.
+template <typename Buffer, typename Buffers>
+class consuming_buffers
+{
+public:
+  // The type for each element in the list of buffers.
+  typedef Buffer value_type;
+
+  // A forward-only iterator type that may be used to read elements.
+  typedef consuming_buffers_iterator<Buffer, typename Buffers::const_iterator>
+    const_iterator;
+
+  // Construct to represent the entire list of buffers.
+  consuming_buffers(const Buffers& buffers)
+    : buffers_(buffers),
+      at_end_(buffers_.begin() == buffers_.end()),
+      first_(*buffers_.begin()),
+      begin_remainder_(buffers_.begin()),
+      max_size_((std::numeric_limits<std::size_t>::max)())
+  {
+    if (!at_end_)
+      ++begin_remainder_;
+  }
+
+  // Copy constructor.
+  consuming_buffers(const consuming_buffers& other)
+    : buffers_(other.buffers_),
+      at_end_(other.at_end_),
+      first_(other.first_),
+      begin_remainder_(buffers_.begin()),
+      max_size_(other.max_size_)
+  {
+    typename Buffers::const_iterator first = other.buffers_.begin();
+    typename Buffers::const_iterator second = other.begin_remainder_;
+    std::advance(begin_remainder_, std::distance(first, second));
+  }
+
+  // Assignment operator.
+  consuming_buffers& operator=(const consuming_buffers& other)
+  {
+    buffers_ = other.buffers_;
+    at_end_ = other.at_end_;
+    first_ = other.first_;
+    begin_remainder_ = buffers_.begin();
+    typename Buffers::const_iterator first = other.buffers_.begin();
+    typename Buffers::const_iterator second = other.begin_remainder_;
+    std::advance(begin_remainder_, std::distance(first, second));
+    max_size_ = other.max_size_;
+    return *this;
+  }
+
+  // Get a forward-only iterator to the first element.
+  const_iterator begin() const
+  {
+    return const_iterator(at_end_, first_,
+        begin_remainder_, buffers_.end(), max_size_);
+  }
+
+  // Get a forward-only iterator for one past the last element.
+  const_iterator end() const
+  {
+    return const_iterator();
+  }
+
+  // Set the maximum size for a single transfer.
+  void prepare(std::size_t max_size)
+  {
+    max_size_ = max_size;
+  }
+
+  // Consume the specified number of bytes from the buffers.
+  void consume(std::size_t size)
+  {
+    // Remove buffers from the start until the specified size is reached.
+    while (size > 0 && !at_end_)
+    {
+      if (buffer_size(first_) <= size)
+      {
+        size -= buffer_size(first_);
+        if (begin_remainder_ == buffers_.end())
+          at_end_ = true;
+        else
+          first_ = *begin_remainder_++;
+      }
+      else
+      {
+        first_ = first_ + size;
+        size = 0;
+      }
+    }
+
+    // Remove any more empty buffers at the start.
+    while (!at_end_ && buffer_size(first_) == 0)
+    {
+      if (begin_remainder_ == buffers_.end())
+        at_end_ = true;
+      else
+        first_ = *begin_remainder_++;
+    }
+  }
+
+private:
+  Buffers buffers_;
+  bool at_end_;
+  Buffer first_;
+  typename Buffers::const_iterator begin_remainder_;
+  std::size_t max_size_;
+};
+
+// Specialisation for null_buffers to ensure that the null_buffers type is
+// always passed through to the underlying read or write operation.
+template <typename Buffer>
+class consuming_buffers<Buffer, asio::null_buffers>
+  : public asio::null_buffers
+{
+public:
+  consuming_buffers(const asio::null_buffers&)
+  {
+    // No-op.
+  }
+
+  void prepare(std::size_t)
+  {
+    // No-op.
+  }
+
+  void consume(std::size_t)
+  {
+    // No-op.
+  }
+};
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_DETAIL_CONSUMING_BUFFERS_HPP