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

Sources/OpenVPN3/openvpn/buffer/bufcomplete.hpp

@@ -0,0 +1,112 @@
+//    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_BUFFER_BUFCOMPLETE_H
+#define OPENVPN_BUFFER_BUFCOMPLETE_H
+
+#include <cstdint>    // for std::uint32_t, uint16_t, uint8_t
+#include <algorithm>  // for std::min
+
+#include <openvpn/buffer/buffer.hpp>
+
+namespace openvpn {
+
+  class BufferComplete
+  {
+  public:
+    /* each advance/get method returns false if message is incomplete */
+
+    bool advance(size_t size)
+    {
+      while (size)
+	{
+	  if (!fetch_buffer())
+	    return false;
+	  const size_t s = std::min(size, buf.size());
+	  buf.advance(s);
+	  size -= s;
+	}
+      return true;
+    }
+
+    // assumes embedded big-endian uint16_t length in the stream
+    bool advance_string()
+    {
+      std::uint8_t h, l;
+      if (!get(h))
+	return false;
+      if (!get(l))
+	return false;
+      return advance(size_t(h) << 8 | size_t(l));
+    }
+
+    bool advance_to_null()
+    {
+      std::uint8_t c;
+      while (get(c))
+	{
+	  if (!c)
+	    return true;
+	}
+      return false;
+    }
+
+    bool get(std::uint8_t& c)
+    {
+      if (!fetch_buffer())
+	return false;
+      c = buf.pop_front();
+      return true;
+    }
+
+    bool defined() const
+    {
+      return buf.defined();
+    }
+
+  protected:
+    void reset_buf(const Buffer& buf_arg)
+    {
+      buf = buf_arg;
+    }
+
+    void reset_buf()
+    {
+      buf.reset_content();
+    }
+
+  private:
+    virtual void next_buffer() = 0;
+
+    bool fetch_buffer()
+    {
+      if (buf.defined())
+	return true;
+      next_buffer();
+      return buf.defined();
+    }
+
+    Buffer buf;
+  };
+
+}
+
+#endif