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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/spdy_headers_block_parser.h"
#include <memory>
#include "base/sys_byteorder.h"
namespace net {
SpdyHeadersBlockParserReader::SpdyHeadersBlockParserReader(
base::StringPiece prefix,
base::StringPiece suffix)
: prefix_(prefix),
suffix_(suffix),
in_suffix_(false),
offset_(0) {}
size_t SpdyHeadersBlockParserReader::Available() {
if (in_suffix_) {
return suffix_.length() - offset_;
} else {
return prefix_.length() + suffix_.length() - offset_;
}
}
bool SpdyHeadersBlockParserReader::ReadN(size_t count, char* out) {
if (Available() < count)
return false;
if (!in_suffix_ && count > (prefix_.length() - offset_)) {
count -= prefix_.length() - offset_;
out = std::copy(prefix_.begin() + offset_, prefix_.end(), out);
in_suffix_ = true;
offset_ = 0;
// Fallthrough to suffix read.
} else if (!in_suffix_) {
// Read is satisfied by the prefix.
DCHECK_GE(prefix_.length() - offset_, count);
std::copy(prefix_.begin() + offset_,
prefix_.begin() + offset_ + count,
out);
offset_ += count;
return true;
}
// Read is satisfied by the suffix.
DCHECK(in_suffix_);
DCHECK_GE(suffix_.length() - offset_, count);
std::copy(suffix_.begin() + offset_,
suffix_.begin() + offset_ + count,
out);
offset_ += count;
return true;
}
std::vector<char> SpdyHeadersBlockParserReader::Remainder() {
std::vector<char> remainder(Available(), '\0');
if (remainder.size()) {
ReadN(remainder.size(), &remainder[0]);
}
DCHECK_EQ(0u, Available());
return remainder;
}
SpdyHeadersBlockParser::SpdyHeadersBlockParser(
SpdyHeadersHandlerInterface* handler) : state_(READING_HEADER_BLOCK_LEN),
remaining_key_value_pairs_for_frame_(0), next_field_len_(0),
handler_(handler) {
}
SpdyHeadersBlockParser::~SpdyHeadersBlockParser() {}
bool SpdyHeadersBlockParser::ParseUInt32(Reader* reader,
uint32_t* parsed_value) {
// Are there enough bytes available?
if (reader->Available() < sizeof(uint32_t)) {
return false;
}
// Read the required bytes, convert from network to host
// order and return the parsed out integer.
char buf[sizeof(uint32_t)];
reader->ReadN(sizeof(uint32_t), buf);
*parsed_value = base::NetToHost32(*reinterpret_cast<const uint32_t *>(buf));
return true;
}
void SpdyHeadersBlockParser::Reset() {
// Clear any saved state about the last headers block.
headers_block_prefix_.clear();
state_ = READING_HEADER_BLOCK_LEN;
}
void SpdyHeadersBlockParser::HandleControlFrameHeadersData(
const char* headers_data, size_t len) {
// Only do something if we received anything new.
if (len == 0) {
return;
}
// Reader avoids copying data.
base::StringPiece prefix;
if (headers_block_prefix_.size()) {
prefix.set(&headers_block_prefix_[0], headers_block_prefix_.size());
}
Reader reader(prefix, base::StringPiece(headers_data, len));
// If we didn't parse out yet the number of key-value pairs in this
// headers block, try to do it now (succeeds if we received enough bytes).
if (state_ == READING_HEADER_BLOCK_LEN) {
if (ParseUInt32(&reader, &remaining_key_value_pairs_for_frame_)) {
handler_->OnHeaderBlock(remaining_key_value_pairs_for_frame_);
state_ = READING_KEY_LEN;
} else {
headers_block_prefix_ = reader.Remainder();
return;
}
}
// Parse out and handle the key-value pairs.
while (remaining_key_value_pairs_for_frame_ > 0) {
// Parse the key-value length, in case we don't already have it.
if ((state_ == READING_KEY_LEN) || (state_ == READING_VALUE_LEN)) {
if (ParseUInt32(&reader, &next_field_len_)) {
state_ == READING_KEY_LEN ? state_ = READING_KEY :
state_ = READING_VALUE;
} else {
// Did not receive enough bytes.
break;
}
}
// Parse the next field if we received enough bytes.
if (reader.Available() >= next_field_len_) {
// Copy the field from the cord.
char* key_value_buf(new char[next_field_len_]);
reader.ReadN(next_field_len_, key_value_buf);
// Is this field a key?
if (state_ == READING_KEY) {
current_key.reset(key_value_buf);
key_len_ = next_field_len_;
state_ = READING_VALUE_LEN;
} else if (state_ == READING_VALUE) {
// We already had the key, now we got its value.
current_value.reset(key_value_buf);
// Call the handler for the key-value pair that we received.
handler_->OnKeyValuePair(
base::StringPiece(current_key.get(), key_len_),
base::StringPiece(current_value.get(), next_field_len_));
// Free allocated key and value strings.
current_key.reset();
current_value.reset();
// Finished handling a key-value pair.
remaining_key_value_pairs_for_frame_--;
// Finished handling a header, prepare for the next one.
state_ = READING_KEY_LEN;
}
} else {
// Did not receive enough bytes.
break;
}
}
// Unread suffix becomes the prefix upon next invocation.
headers_block_prefix_ = reader.Remainder();
// Did we finish handling the current block?
if (remaining_key_value_pairs_for_frame_ == 0) {
handler_->OnHeaderBlockEnd();
Reset();
}
}
} // namespace net
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