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// Copyright (c) 2012 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_frame_builder.h"
#include <algorithm>
#include <cstdint>
#include <limits>
#include "base/logging.h"
#include "net/spdy/spdy_bug_tracker.h"
#include "net/spdy/spdy_framer.h"
#include "net/spdy/spdy_protocol.h"
#include "net/spdy/zero_copy_output_buffer.h"
namespace net {
SpdyFrameBuilder::SpdyFrameBuilder(size_t size)
: buffer_(new char[size]), capacity_(size), length_(0), offset_(0) {}
SpdyFrameBuilder::SpdyFrameBuilder(size_t size, ZeroCopyOutputBuffer* output)
: buffer_(output == nullptr ? new char[size] : nullptr),
output_(output),
capacity_(size),
length_(0),
offset_(0) {}
SpdyFrameBuilder::~SpdyFrameBuilder() {
}
char* SpdyFrameBuilder::GetWritableBuffer(size_t length) {
if (!CanWrite(length)) {
return nullptr;
}
return buffer_.get() + offset_ + length_;
}
char* SpdyFrameBuilder::GetWritableOutput(size_t length,
size_t* actual_length) {
char* dest = nullptr;
int size = 0;
if (!CanWrite(length)) {
return nullptr;
}
output_->Next(&dest, &size);
*actual_length = std::min(length, (size_t)size);
return dest;
}
bool SpdyFrameBuilder::Seek(size_t length) {
if (!CanWrite(length)) {
return false;
}
if (output_ == nullptr) {
length_ += length;
} else {
output_->AdvanceWritePtr(length);
length_ += length;
}
return true;
}
bool SpdyFrameBuilder::BeginNewFrame(const SpdyFramer& framer,
SpdyFrameType type,
uint8_t flags,
SpdyStreamId stream_id) {
DCHECK(IsDefinedFrameType(type));
DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
bool success = true;
if (length_ > 0) {
// Update length field for previous frame.
OverwriteLength(framer, length_ - kFrameHeaderSize);
SPDY_BUG_IF(framer.GetFrameMaximumSize() < length_)
<< "Frame length " << length_
<< " is longer than the maximum allowed length.";
}
offset_ += length_;
length_ = 0;
// Assume all remaining capacity will be used for this frame. If not,
// the length will get overwritten when we begin the next frame.
// Don't check for length limits here because this may be larger than the
// actual frame length.
success &= WriteUInt24(capacity_ - offset_ - kFrameHeaderSize);
success &= WriteUInt8(type);
success &= WriteUInt8(flags);
success &= WriteUInt32(stream_id);
DCHECK_EQ(framer.GetDataFrameMinimumSize(), length_);
return success;
}
bool SpdyFrameBuilder::BeginNewFrame(const SpdyFramer& framer,
SpdyFrameType type,
uint8_t flags,
SpdyStreamId stream_id,
size_t length) {
DCHECK(IsDefinedFrameType(type));
DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
bool success = true;
SPDY_BUG_IF(framer.GetFrameMaximumSize() < length_)
<< "Frame length " << length_
<< " is longer than the maximum allowed length.";
offset_ += length_;
length_ = 0;
success &= WriteUInt24(length);
success &= WriteUInt8(type);
success &= WriteUInt8(flags);
success &= WriteUInt32(stream_id);
DCHECK_EQ(framer.GetDataFrameMinimumSize(), length_);
return success;
}
bool SpdyFrameBuilder::WriteStringPiece16(const base::StringPiece& value) {
if (value.size() > 0xffff) {
DCHECK(false) << "Tried to write string with length > 16bit.";
return false;
}
if (!WriteUInt16(static_cast<uint16_t>(value.size()))) {
return false;
}
return WriteBytes(value.data(), static_cast<uint16_t>(value.size()));
}
bool SpdyFrameBuilder::WriteStringPiece32(const base::StringPiece& value) {
if (!WriteUInt32(value.size())) {
return false;
}
return WriteBytes(value.data(), value.size());
}
bool SpdyFrameBuilder::WriteBytes(const void* data, uint32_t data_len) {
if (!CanWrite(data_len)) {
return false;
}
if (output_ == nullptr) {
char* dest = GetWritableBuffer(data_len);
memcpy(dest, data, data_len);
Seek(data_len);
} else {
char* dest = nullptr;
size_t size = 0;
size_t total_written = 0;
const char* data_ptr = reinterpret_cast<const char*>(data);
while (data_len > 0) {
dest = GetWritableOutput(data_len, &size);
if (dest == nullptr || size == 0) {
// Unable to make progress.
return false;
}
uint32_t to_copy = std::min((size_t)data_len, size);
const char* src = data_ptr + total_written;
memcpy(dest, src, to_copy);
Seek(to_copy);
data_len -= to_copy;
total_written += to_copy;
}
}
return true;
}
bool SpdyFrameBuilder::OverwriteLength(const SpdyFramer& framer,
size_t length) {
DCHECK_GE(framer.GetFrameMaximumSize(), length);
bool success = false;
const size_t old_length = length_;
length_ = 0;
success = WriteUInt24(length);
length_ = old_length;
return success;
}
bool SpdyFrameBuilder::CanWrite(size_t length) const {
if (length > kLengthMask) {
DCHECK(false);
return false;
}
if (output_ == nullptr) {
if (offset_ + length_ + length > capacity_) {
DLOG(FATAL) << "Requested: " << length << " capacity: " << capacity_
<< " used: " << offset_ + length_;
return false;
}
} else {
if (length > output_->BytesFree()) {
return false;
}
}
return true;
}
} // namespace net
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