Merge commit '86cc97e55fe346502462284d2e636a2b3708163e' as 'Sources/OpenVPN3'

2026-04-24 00:00:05 +08:00 · 2020-02-24 14:43:11 +03:00
parent 133b3756e6 86cc97e55f
commit 32f1555929
655 changed files with 146468 additions and 0 deletions
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+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2017 OpenVPN Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Affero General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    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 Affero General Public License for more details.
+//
+//    You should have received a copy of the GNU Affero General Public License
+//    along with this program in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef OPENVPN_COMMON_MSGWIN_H
+#define OPENVPN_COMMON_MSGWIN_H
+
+#include <deque>
+
+#include <openvpn/common/size.hpp>
+#include <openvpn/common/exception.hpp>
+
+// Fundamental, lowest-level object of OpenVPN protocol reliability layer
+
+namespace openvpn {
+
+  // MessageWindow --
+  //   On receiving side: used to order packets which may be received out-of-order
+  //   On sending side: used to buffer unacknowledged packets
+  //   M : message class, must define default constructor, defined(), and erase() methods
+  //   id_t : sequence number object, usually unsigned int
+  template <typename M, typename id_t>
+  class MessageWindow
+  {
+  public:
+    OPENVPN_SIMPLE_EXCEPTION(message_window_ref_by_id);
+    OPENVPN_SIMPLE_EXCEPTION(message_window_rm_head);
+
+    MessageWindow()
+      : head_id_(0), span_(0) {}
+
+    MessageWindow(const id_t starting_head_id, const id_t span)
+      : head_id_(starting_head_id), span_(span) {}
+
+    void init(const id_t starting_head_id, const id_t span)
+    {
+      head_id_ = starting_head_id;
+      span_ = span;
+      q_.clear();
+    }
+
+    // Return true if id is within current window
+    bool in_window(const id_t id) const
+    {
+      return id >= head_id_ && id < head_id_ + span_;
+    }
+
+    // Return true if id is before current window
+    bool pre_window(const id_t id) const
+    {
+      return id < head_id_;
+    }
+
+    // Return a reference to M object at id, throw exception
+    // if id is not in current window
+    M& ref_by_id(const id_t id)
+    {
+      if (in_window(id))
+	{
+	  grow(id);
+	  return q_[id - head_id_];
+	}
+      else
+	throw message_window_ref_by_id();
+    }
+
+    // Remove the M object at id, is a no-op if
+    // id not in window.  Do a purge() as a last
+    // step to advance the head_id_ if it's now
+    // pointing at undefined M objects.
+    void rm_by_id(const id_t id)
+    {
+      if (in_window(id))
+	{
+	  grow(id);
+	  M& m = q_[id - head_id_];
+	  m.erase();
+	}
+      purge();
+    }
+
+    // Return true if an object at head of queue is defined
+    bool head_defined() const
+    {
+      return (!q_.empty() && q_.front().defined());
+    }
+
+    // Return the id that the object at the head of the queue
+    // would have (even if it isn't defined yet).
+    id_t head_id() const { return head_id_; }
+
+    // Return the id of one past the end of the window
+    id_t tail_id() const { return head_id_ + span_; }
+
+    // Return the window size
+    id_t span() const { return span_; }
+
+    // Return a reference to the object at the front of the queue
+    M& ref_head() { return q_.front(); }
+
+    // Remove the object at head of queue, throw an exception if undefined
+    void rm_head()
+    {
+      if (head_defined())
+	rm_head_nocheck();
+      else
+	throw message_window_rm_head();
+    }
+
+    // Remove the object at head of queue without error checking (other than
+    // that provided by std::deque object).  Don't call this method unless
+    // head_defined() returns true.
+    void rm_head_nocheck()
+    {
+      q_.front().erase();
+      q_.pop_front();
+      ++head_id_;
+    }
+
+  private:
+    // Expand the queue if necessary so that id maps
+    // to an object in the queue
+    void grow(const id_t id)
+    {
+      const size_t needed_index = id - head_id_;
+      while (q_.size() <= needed_index)
+	q_.push_back(M());
+    }
+
+    // Purge all undefined objects at the head of
+    // the queue, advancing the head_id_
+    void purge()
+    {
+      while (!q_.empty() && q_.front().erased())
+	{
+	  q_.pop_front();
+	  ++head_id_;
+	}
+    }
+
+    id_t head_id_; // id of msgs[0]
+    id_t span_;
+    std::deque<M> q_;
+  };
+
+} // namespace openvpn
+
+#endif // OPENVPN_COMMON_MSGWIN_H