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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/spdy/hpack_decoder.h"
#include "base/basictypes.h"
#include "base/logging.h"
#include "base/strings/string_util.h"
#include "net/spdy/hpack_constants.h"
#include "net/spdy/hpack_output_stream.h"
namespace net {
using base::StringPiece;
using std::string;
namespace {
const uint8 kNoState = 0;
// Set on entries added to the reference set during this decoding.
const uint8 kReferencedThisEncoding = 1;
} // namespace
HpackDecoder::HpackDecoder(const HpackHuffmanTable& table)
: max_string_literal_size_(kDefaultMaxStringLiteralSize),
huffman_table_(table) {}
HpackDecoder::~HpackDecoder() {}
bool HpackDecoder::HandleControlFrameHeadersData(SpdyStreamId id,
const char* headers_data,
size_t headers_data_length) {
decoded_block_.clear();
size_t new_size = headers_block_buffer_.size() + headers_data_length;
if (new_size > kMaxDecodeBufferSize) {
return false;
}
headers_block_buffer_.insert(headers_block_buffer_.end(),
headers_data,
headers_data + headers_data_length);
return true;
}
bool HpackDecoder::HandleControlFrameHeadersComplete(SpdyStreamId id) {
HpackInputStream input_stream(max_string_literal_size_,
headers_block_buffer_);
while (input_stream.HasMoreData()) {
if (!DecodeNextOpcode(&input_stream))
return false;
}
headers_block_buffer_.clear();
// Emit everything in the reference set that hasn't already been emitted.
// Also clear entry state for the next decoded headers block.
// TODO(jgraettinger): We may need to revisit the order in which headers
// are emitted (b/14051713).
for (HpackEntry::OrderedSet::const_iterator it =
header_table_.reference_set().begin();
it != header_table_.reference_set().end(); ++it) {
HpackEntry* entry = *it;
if (entry->state() == kNoState) {
HandleHeaderRepresentation(entry->name(), entry->value());
} else {
entry->set_state(kNoState);
}
}
// Emit the Cookie header, if any crumbles were encountered.
if (!cookie_name_.empty()) {
decoded_block_[cookie_name_] = cookie_value_;
cookie_name_.clear();
cookie_value_.clear();
}
return true;
}
void HpackDecoder::HandleHeaderRepresentation(StringPiece name,
StringPiece value) {
typedef std::pair<std::map<string, string>::iterator, bool> InsertResult;
// TODO(jgraettinger): HTTP/2 requires strict lowercasing of headers,
// and the permissiveness here isn't wanted. Back this out in upstream.
if (LowerCaseEqualsASCII(name.begin(), name.end(), "cookie")) {
if (cookie_name_.empty()) {
cookie_name_.assign(name.data(), name.size());
cookie_value_.assign(value.data(), value.size());
} else {
cookie_value_ += "; ";
cookie_value_.insert(cookie_value_.end(), value.begin(), value.end());
}
} else {
InsertResult result = decoded_block_.insert(
std::make_pair(name.as_string(), value.as_string()));
if (!result.second) {
result.first->second.push_back('\0');
result.first->second.insert(result.first->second.end(),
value.begin(),
value.end());
}
}
}
bool HpackDecoder::DecodeNextOpcode(HpackInputStream* input_stream) {
// Implements 4.4: Encoding context update. Context updates are a special-case
// of indexed header, and must be tested prior to |kIndexedOpcode| below.
if (input_stream->MatchPrefixAndConsume(kEncodingContextOpcode)) {
return DecodeNextContextUpdate(input_stream);
}
// Implements 4.2: Indexed Header Field Representation.
if (input_stream->MatchPrefixAndConsume(kIndexedOpcode)) {
return DecodeNextIndexedHeader(input_stream);
}
// Implements 4.3.1: Literal Header Field without Indexing.
if (input_stream->MatchPrefixAndConsume(kLiteralNoIndexOpcode)) {
return DecodeNextLiteralHeader(input_stream, false);
}
// Implements 4.3.2: Literal Header Field with Incremental Indexing.
if (input_stream->MatchPrefixAndConsume(kLiteralIncrementalIndexOpcode)) {
return DecodeNextLiteralHeader(input_stream, true);
}
// Unrecognized opcode.
return false;
}
bool HpackDecoder::DecodeNextContextUpdate(HpackInputStream* input_stream) {
if (input_stream->MatchPrefixAndConsume(kEncodingContextEmptyReferenceSet)) {
header_table_.ClearReferenceSet();
return true;
}
if (input_stream->MatchPrefixAndConsume(kEncodingContextNewMaximumSize)) {
uint32 size = 0;
if (!input_stream->DecodeNextUint32(&size)) {
return false;
}
if (size > header_table_.settings_size_bound()) {
return false;
}
header_table_.SetMaxSize(size);
return true;
}
// Unrecognized encoding context update.
return false;
}
bool HpackDecoder::DecodeNextIndexedHeader(HpackInputStream* input_stream) {
uint32 index = 0;
if (!input_stream->DecodeNextUint32(&index))
return false;
// If index == 0, |kEncodingContextOpcode| would have matched.
CHECK_NE(index, 0u);
HpackEntry* entry = header_table_.GetByIndex(index);
if (entry == NULL)
return false;
if (entry->IsStatic()) {
HandleHeaderRepresentation(entry->name(), entry->value());
HpackEntry* new_entry = header_table_.TryAddEntry(
entry->name(), entry->value());
if (new_entry) {
header_table_.Toggle(new_entry);
new_entry->set_state(kReferencedThisEncoding);
}
} else {
entry->set_state(kNoState);
if (header_table_.Toggle(entry)) {
HandleHeaderRepresentation(entry->name(), entry->value());
entry->set_state(kReferencedThisEncoding);
}
}
return true;
}
bool HpackDecoder::DecodeNextLiteralHeader(HpackInputStream* input_stream,
bool should_index) {
StringPiece name;
if (!DecodeNextName(input_stream, &name))
return false;
StringPiece value;
if (!DecodeNextStringLiteral(input_stream, false, &value))
return false;
HandleHeaderRepresentation(name, value);
if (!should_index)
return true;
HpackEntry* new_entry = header_table_.TryAddEntry(name, value);
if (new_entry) {
header_table_.Toggle(new_entry);
new_entry->set_state(kReferencedThisEncoding);
}
return true;
}
bool HpackDecoder::DecodeNextName(
HpackInputStream* input_stream, StringPiece* next_name) {
uint32 index_or_zero = 0;
if (!input_stream->DecodeNextUint32(&index_or_zero))
return false;
if (index_or_zero == 0)
return DecodeNextStringLiteral(input_stream, true, next_name);
const HpackEntry* entry = header_table_.GetByIndex(index_or_zero);
if (entry == NULL) {
return false;
} else if (entry->IsStatic()) {
*next_name = entry->name();
} else {
// |entry| could be evicted as part of this insertion. Preemptively copy.
key_buffer_.assign(entry->name());
*next_name = key_buffer_;
}
return true;
}
bool HpackDecoder::DecodeNextStringLiteral(HpackInputStream* input_stream,
bool is_key,
StringPiece* output) {
if (input_stream->MatchPrefixAndConsume(kStringLiteralHuffmanEncoded)) {
string* buffer = is_key ? &key_buffer_ : &value_buffer_;
bool result = input_stream->DecodeNextHuffmanString(huffman_table_, buffer);
*output = StringPiece(*buffer);
return result;
} else if (input_stream->MatchPrefixAndConsume(
kStringLiteralIdentityEncoded)) {
return input_stream->DecodeNextIdentityString(output);
} else {
return false;
}
}
} // namespace net
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