net/websockets/websocket_deflater.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_
   6 #define NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_
   7
   8 #include <deque>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "net/base/net_export.h"
  15
  16 extern "C" struct z_stream_s;
  17
  18 namespace net {
  19
  20 class IOBufferWithSize;
  21
  22 class NET_EXPORT_PRIVATE WebSocketDeflater {
  23  public:
  24   // Do not reorder or remove entries of this enum. The values of them are used
  25   // in UMA.
  26   enum ContextTakeOverMode {
  27     DO_NOT_TAKE_OVER_CONTEXT,
  28     TAKE_OVER_CONTEXT,
  29     NUM_CONTEXT_TAKEOVER_MODE_TYPES,
  30   };
  31
  32   explicit WebSocketDeflater(ContextTakeOverMode mode);
  33   ~WebSocketDeflater();
  34
  35   // Returns true if there is no error and false otherwise.
  36   // This function must be called exactly once before calling any of
  37   // following methods.
  38   // |window_bits| must be between 8 and 15 (both inclusive).
  39   bool Initialize(int window_bits);
  40
  41   // Adds bytes to |stream_|.
  42   // Returns true if there is no error and false otherwise.
  43   bool AddBytes(const char* data, size_t size);
  44
  45   // Flushes the current processing data.
  46   // Returns true if there is no error and false otherwise.
  47   bool Finish();
  48
  49   // Pushes "\x00\x00\xff\xff" to the end of the buffer.
  50   void PushSyncMark();
  51
  52   // Returns the current deflated output.
  53   // If the current output is larger than |size| bytes,
  54   // returns the first |size| bytes of the current output.
  55   // The returned bytes will be dropped from the current output and never be
  56   // returned thereafter.
  57   scoped_refptr<IOBufferWithSize> GetOutput(size_t size);
  58
  59   // Returns the size of the current deflated output.
  60   size_t CurrentOutputSize() const { return buffer_.size(); }
  61
  62  private:
  63   void ResetContext();
  64   int Deflate(int flush);
  65
  66   scoped_ptr<z_stream_s> stream_;
  67   ContextTakeOverMode mode_;
  68   std::deque<char> buffer_;
  69   std::vector<char> fixed_buffer_;
  70   // true if bytes were added after last Finish().
  71   bool are_bytes_added_;
  72
  73   DISALLOW_COPY_AND_ASSIGN(WebSocketDeflater);
  74 };
  75
  76 }  // namespace net
  77
  78 #endif  // NET_WEBSOCKETS_WEBSOCKET_DEFLATER_H_