net/websockets/websocket_inflater.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_INFLATER_H_
   6 #define NET_WEBSOCKETS_WEBSOCKET_INFLATER_H_
   7
   8 #include <deque>
   9 #include <utility>
  10 #include <vector>
  11
  12 #include "base/basictypes.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "net/base/net_export.h"
  16
  17 extern "C" struct z_stream_s;
  18
  19 namespace net {
  20
  21 class IOBufferWithSize;
  22
  23 // WebSocketInflater uncompresses data compressed by DEFLATE algorithm.
  24 class NET_EXPORT_PRIVATE WebSocketInflater {
  25  public:
  26   WebSocketInflater();
  27   // |input_queue_capacity| is a capacity for each contiguous block in the
  28   // input queue. The input queue can grow without limit.
  29   WebSocketInflater(size_t input_queue_capacity, size_t output_buffer_capacity);
  30   ~WebSocketInflater();
  31
  32   // Returns true if there is no error.
  33   // |window_bits| must be between 8 and 15 (both inclusive).
  34   // This function must be called exactly once before calling any of the
  35   // following functions.
  36   bool Initialize(int window_bits);
  37
  38   // Adds bytes to |stream_|.
  39   // Returns true if there is no error.
  40   // If the size of the output data reaches the capacity of the output buffer,
  41   // the following input data will be "choked", i.e. stored in the input queue,
  42   // staying compressed.
  43   bool AddBytes(const char* data, size_t size);
  44
  45   // Flushes the input.
  46   // Returns true if there is no error.
  47   bool Finish();
  48
  49   // Returns up to |size| bytes of the decompressed output.
  50   // Returns null if there is an inflation error.
  51   // The returned bytes will be dropped from the current output and never be
  52   // returned again.
  53   // If some input data is choked, calling this function may restart the
  54   // inflation process.
  55   // This means that even if you call |Finish()| and call |GetOutput()| with
  56   // size = |CurrentOutputSize()|, the inflater may have some remaining data.
  57   // To confirm the inflater emptiness, you should check whether
  58   // |CurrentOutputSize()| is zero.
  59   scoped_refptr<IOBufferWithSize> GetOutput(size_t size);
  60
  61   // Returns the size of the current inflated output.
  62   size_t CurrentOutputSize() const { return output_buffer_.Size(); }
  63
  64   static const size_t kDefaultBufferCapacity = 512;
  65   static const size_t kDefaultInputIOBufferCapacity = 512;
  66
  67  private:
  68   // Ring buffer with fixed capacity.
  69   class OutputBuffer {
  70    public:
  71     explicit OutputBuffer(size_t capacity);
  72     ~OutputBuffer();
  73
  74     size_t Size() const;
  75     // Returns (tail pointer, availabe size).
  76     // A user can push data to the queue by writing the data to
  77     // the area returned by this function and calling AdvanceTail.
  78     std::pair<char*, size_t> GetTail();
  79     void Read(char* dest, size_t size);
  80     void AdvanceTail(size_t advance);
  81
  82    private:
  83     void AdvanceHead(size_t advance);
  84
  85     const size_t capacity_;
  86     std::vector<char> buffer_;
  87     size_t head_;
  88     size_t tail_;
  89   };
  90
  91   class InputQueue {
  92    public:
  93     // |capacity| is used for the capacity of each IOBuffer in this queue.
  94     // this queue itself can grow without limit.
  95     explicit InputQueue(size_t capacity);
  96     ~InputQueue();
  97
  98     // Returns (data pointer, size), the first component of unconsumed data.
  99     // The type of data pointer is non-const because |inflate| function
 100     // requires so.
 101     std::pair<char*, size_t> Top();
 102     bool IsEmpty() const { return buffers_.empty(); }
 103     void Push(const char* data, size_t size);
 104     // Consumes the topmost |size| bytes.
 105     // |size| must be less than or equal to the first buffer size.
 106     void Consume(size_t size);
 107
 108    private:
 109     size_t PushToLastBuffer(const char* data, size_t size);
 110
 111     const size_t capacity_;
 112     size_t head_of_first_buffer_;
 113     size_t tail_of_last_buffer_;
 114     std::deque<scoped_refptr<IOBufferWithSize> > buffers_;
 115   };
 116
 117   int InflateWithFlush(const char* next_in, size_t avail_in);
 118   int Inflate(const char* next_in, size_t avail_in, int flush);
 119   int InflateChokedInput();
 120
 121   scoped_ptr<z_stream_s> stream_;
 122   InputQueue input_queue_;
 123   OutputBuffer output_buffer_;
 124
 125   DISALLOW_COPY_AND_ASSIGN(WebSocketInflater);
 126 };
 127
 128 }  // namespace net
 129
 130 #endif  // NET_WEBSOCKETS_WEBSOCKET_INFLATER_H_