net/quic/quic_spdy_compressor.cc

   1 // Copyright (c) 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 #include "net/quic/quic_spdy_compressor.h"
   6
   7 #include "base/basictypes.h"
   8 #include "base/memory/scoped_ptr.h"
   9
  10 using std::string;
  11
  12 namespace net {
  13
  14 QuicSpdyCompressor::QuicSpdyCompressor()
  15     : spdy_framer_(SPDY3),
  16       header_sequence_id_(1) {
  17   spdy_framer_.set_enable_compression(true);
  18 }
  19
  20 QuicSpdyCompressor::~QuicSpdyCompressor() {
  21 }
  22
  23 string QuicSpdyCompressor::CompressHeadersWithPriority(
  24     QuicPriority priority,
  25     const SpdyHeaderBlock& headers) {
  26   return CompressHeadersInternal(priority, headers, true);
  27 }
  28
  29 string QuicSpdyCompressor::CompressHeaders(
  30     const SpdyHeaderBlock& headers) {
  31   // CompressHeadersInternal ignores priority when write_priority is false.
  32   return CompressHeadersInternal(0 /* ignored */, headers, false);
  33 }
  34
  35 string QuicSpdyCompressor::CompressHeadersInternal(
  36     QuicPriority priority,
  37     const SpdyHeaderBlock& headers,
  38     bool write_priority) {
  39   // TODO(rch): Modify the SpdyFramer to expose a
  40   // CreateCompressedHeaderBlock method, or some such.
  41   SpdyStreamId stream_id = 3;    // unused.
  42   scoped_ptr<SpdyFrame> frame(spdy_framer_.CreateHeaders(
  43       stream_id, CONTROL_FLAG_NONE, &headers));
  44
  45   // The size of the spdy HEADER frame's fixed prefix which
  46   // needs to be stripped off from the resulting frame.
  47   const size_t header_frame_prefix_len = 12;
  48   string serialized = string(frame->data() + header_frame_prefix_len,
  49                              frame->size() - header_frame_prefix_len);
  50   uint32 serialized_len = serialized.length();
  51   char priority_str[sizeof(priority)];
  52   memcpy(&priority_str, &priority, sizeof(priority));
  53   char id_str[sizeof(header_sequence_id_)];
  54   memcpy(&id_str, &header_sequence_id_, sizeof(header_sequence_id_));
  55   char len_str[sizeof(serialized_len)];
  56   memcpy(&len_str, &serialized_len, sizeof(serialized_len));
  57   string compressed;
  58   int priority_len = write_priority ? arraysize(priority_str) : 0;
  59   compressed.reserve(
  60       priority_len + arraysize(id_str) + arraysize(len_str) + serialized_len);
  61   if (write_priority) {
  62     compressed.append(priority_str, arraysize(priority_str));
  63   }
  64   compressed.append(id_str, arraysize(id_str));
  65   compressed.append(len_str, arraysize(len_str));
  66   compressed.append(serialized);
  67   ++header_sequence_id_;
  68   return compressed;
  69 }
  70
  71 }  // namespace net