net/spdy/hpack_decoder.cc

   1 // Copyright 2014 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/spdy/hpack_decoder.h"
   6
   7 #include <utility>
   8
   9 #include "base/basictypes.h"
  10 #include "base/logging.h"
  11 #include "net/spdy/hpack_constants.h"
  12 #include "net/spdy/hpack_output_stream.h"
  13
  14 namespace net {
  15
  16 using base::StringPiece;
  17 using std::string;
  18
  19 namespace {
  20
  21 const char kCookieKey[] = "cookie";
  22
  23 }  // namespace
  24
  25 HpackDecoder::HpackDecoder(const HpackHuffmanTable& table)
  26     : max_string_literal_size_(kDefaultMaxStringLiteralSize),
  27       regular_header_seen_(false),
  28       huffman_table_(table) {}
  29
  30 HpackDecoder::~HpackDecoder() {}
  31
  32 bool HpackDecoder::HandleControlFrameHeadersData(SpdyStreamId id,
  33                                                  const char* headers_data,
  34                                                  size_t headers_data_length) {
  35   decoded_block_.clear();
  36
  37   size_t new_size = headers_block_buffer_.size() + headers_data_length;
  38   if (new_size > kMaxDecodeBufferSize) {
  39     return false;
  40   }
  41   headers_block_buffer_.insert(headers_block_buffer_.end(),
  42                                headers_data,
  43                                headers_data + headers_data_length);
  44   return true;
  45 }
  46
  47 bool HpackDecoder::HandleControlFrameHeadersComplete(SpdyStreamId id,
  48                                                      size_t* compressed_len) {
  49   HpackInputStream input_stream(max_string_literal_size_,
  50                                 headers_block_buffer_);
  51   regular_header_seen_ = false;
  52   if (compressed_len) {
  53     *compressed_len = headers_block_buffer_.size();
  54   }
  55   while (input_stream.HasMoreData()) {
  56     if (!DecodeNextOpcode(&input_stream)) {
  57       headers_block_buffer_.clear();
  58       return false;
  59     }
  60   }
  61   headers_block_buffer_.clear();
  62
  63   // Emit the Cookie header, if any crumbles were encountered.
  64   if (!cookie_value_.empty()) {
  65     decoded_block_[kCookieKey] = cookie_value_;
  66     cookie_value_.clear();
  67   }
  68   return true;
  69 }
  70
  71 bool HpackDecoder::HandleHeaderRepresentation(StringPiece name,
  72                                               StringPiece value) {
  73   typedef std::pair<SpdyHeaderBlock::iterator, bool> InsertResult;
  74
  75   // Fail if pseudo-header follows regular header.
  76   if (name.size() > 0) {
  77     if (name[0] == kPseudoHeaderPrefix) {
  78       if (regular_header_seen_) return false;
  79     } else {
  80       regular_header_seen_ = true;
  81     }
  82   }
  83
  84   if (name == kCookieKey) {
  85     if (cookie_value_.empty()) {
  86       cookie_value_.assign(value.data(), value.size());
  87     } else {
  88       cookie_value_ += "; ";
  89       cookie_value_.insert(cookie_value_.end(), value.begin(), value.end());
  90     }
  91   } else {
  92     InsertResult result = decoded_block_.insert(
  93         std::make_pair(name.as_string(), value.as_string()));
  94     if (!result.second) {
  95       result.first->second.push_back('\0');
  96       result.first->second.insert(result.first->second.end(),
  97                                   value.begin(),
  98                                   value.end());
  99     }
 100   }
 101   return true;
 102 }
 103
 104 bool HpackDecoder::DecodeNextOpcode(HpackInputStream* input_stream) {
 105   // Implements 7.1: Indexed Header Field Representation.
 106   if (input_stream->MatchPrefixAndConsume(kIndexedOpcode)) {
 107     return DecodeNextIndexedHeader(input_stream);
 108   }
 109   // Implements 7.2.1: Literal Header Field with Incremental Indexing.
 110   if (input_stream->MatchPrefixAndConsume(kLiteralIncrementalIndexOpcode)) {
 111     return DecodeNextLiteralHeader(input_stream, true);
 112   }
 113   // Implements 7.2.2: Literal Header Field without Indexing.
 114   if (input_stream->MatchPrefixAndConsume(kLiteralNoIndexOpcode)) {
 115     return DecodeNextLiteralHeader(input_stream, false);
 116   }
 117   // Implements 7.2.3: Literal Header Field never Indexed.
 118   // TODO(jgraettinger): Preserve the never-indexed bit.
 119   if (input_stream->MatchPrefixAndConsume(kLiteralNeverIndexOpcode)) {
 120     return DecodeNextLiteralHeader(input_stream, false);
 121   }
 122   // Implements 7.3: Header Table Size Update.
 123   if (input_stream->MatchPrefixAndConsume(kHeaderTableSizeUpdateOpcode)) {
 124     return DecodeNextHeaderTableSizeUpdate(input_stream);
 125   }
 126   // Unrecognized opcode.
 127   return false;
 128 }
 129
 130 bool HpackDecoder::DecodeNextHeaderTableSizeUpdate(
 131     HpackInputStream* input_stream) {
 132   uint32 size = 0;
 133   if (!input_stream->DecodeNextUint32(&size)) {
 134     return false;
 135   }
 136   if (size > header_table_.settings_size_bound()) {
 137     return false;
 138   }
 139   header_table_.SetMaxSize(size);
 140   return true;
 141 }
 142
 143 bool HpackDecoder::DecodeNextIndexedHeader(HpackInputStream* input_stream) {
 144   uint32 index = 0;
 145   if (!input_stream->DecodeNextUint32(&index))
 146     return false;
 147
 148   const HpackEntry* entry = header_table_.GetByIndex(index);
 149   if (entry == NULL)
 150     return false;
 151
 152   return HandleHeaderRepresentation(entry->name(), entry->value());
 153 }
 154
 155 bool HpackDecoder::DecodeNextLiteralHeader(HpackInputStream* input_stream,
 156                                            bool should_index) {
 157   StringPiece name;
 158   if (!DecodeNextName(input_stream, &name))
 159     return false;
 160
 161   StringPiece value;
 162   if (!DecodeNextStringLiteral(input_stream, false, &value))
 163     return false;
 164
 165   if (!HandleHeaderRepresentation(name, value)) return false;
 166
 167   if (!should_index)
 168     return true;
 169
 170   ignore_result(header_table_.TryAddEntry(name, value));
 171   return true;
 172 }
 173
 174 bool HpackDecoder::DecodeNextName(
 175     HpackInputStream* input_stream, StringPiece* next_name) {
 176   uint32 index_or_zero = 0;
 177   if (!input_stream->DecodeNextUint32(&index_or_zero))
 178     return false;
 179
 180   if (index_or_zero == 0)
 181     return DecodeNextStringLiteral(input_stream, true, next_name);
 182
 183   const HpackEntry* entry = header_table_.GetByIndex(index_or_zero);
 184   if (entry == NULL) {
 185     return false;
 186   } else if (entry->IsStatic()) {
 187     *next_name = entry->name();
 188   } else {
 189     // |entry| could be evicted as part of this insertion. Preemptively copy.
 190     key_buffer_.assign(entry->name());
 191     *next_name = key_buffer_;
 192   }
 193   return true;
 194 }
 195
 196 bool HpackDecoder::DecodeNextStringLiteral(HpackInputStream* input_stream,
 197                                            bool is_key,
 198                                            StringPiece* output) {
 199   if (input_stream->MatchPrefixAndConsume(kStringLiteralHuffmanEncoded)) {
 200     string* buffer = is_key ? &key_buffer_ : &value_buffer_;
 201     bool result = input_stream->DecodeNextHuffmanString(huffman_table_, buffer);
 202     *output = StringPiece(*buffer);
 203     return result;
 204   } else if (input_stream->MatchPrefixAndConsume(
 205       kStringLiteralIdentityEncoded)) {
 206     return input_stream->DecodeNextIdentityString(output);
 207   } else {
 208     return false;
 209   }
 210 }
 211
 212 }  // namespace net