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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/server/web_socket_encoder.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/stringprintf.h"
#include "net/base/io_buffer.h"
#include "net/websockets/websocket_extension_parser.h"
namespace net {
const char WebSocketEncoder::kClientExtensions[] =
"Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits";
namespace {
const int kInflaterChunkSize = 16 * 1024;
// Constants for hybi-10 frame format.
typedef int OpCode;
const OpCode kOpCodeContinuation = 0x0;
const OpCode kOpCodeText = 0x1;
const OpCode kOpCodeBinary = 0x2;
const OpCode kOpCodeClose = 0x8;
const OpCode kOpCodePing = 0x9;
const OpCode kOpCodePong = 0xA;
const unsigned char kFinalBit = 0x80;
const unsigned char kReserved1Bit = 0x40;
const unsigned char kReserved2Bit = 0x20;
const unsigned char kReserved3Bit = 0x10;
const unsigned char kOpCodeMask = 0xF;
const unsigned char kMaskBit = 0x80;
const unsigned char kPayloadLengthMask = 0x7F;
const size_t kMaxSingleBytePayloadLength = 125;
const size_t kTwoBytePayloadLengthField = 126;
const size_t kEightBytePayloadLengthField = 127;
const size_t kMaskingKeyWidthInBytes = 4;
WebSocket::ParseResult DecodeFrameHybi17(const base::StringPiece& frame,
bool client_frame,
int* bytes_consumed,
std::string* output,
bool* compressed) {
size_t data_length = frame.length();
if (data_length < 2)
return WebSocket::FRAME_INCOMPLETE;
const char* buffer_begin = const_cast<char*>(frame.data());
const char* p = buffer_begin;
const char* buffer_end = p + data_length;
unsigned char first_byte = *p++;
unsigned char second_byte = *p++;
bool final = (first_byte & kFinalBit) != 0;
bool reserved1 = (first_byte & kReserved1Bit) != 0;
bool reserved2 = (first_byte & kReserved2Bit) != 0;
bool reserved3 = (first_byte & kReserved3Bit) != 0;
int op_code = first_byte & kOpCodeMask;
bool masked = (second_byte & kMaskBit) != 0;
*compressed = reserved1;
if (!final || reserved2 || reserved3)
return WebSocket::FRAME_ERROR; // Only compression extension is supported.
bool closed = false;
switch (op_code) {
case kOpCodeClose:
closed = true;
break;
case kOpCodeText:
break;
case kOpCodeBinary: // We don't support binary frames yet.
case kOpCodeContinuation: // We don't support binary frames yet.
case kOpCodePing: // We don't support binary frames yet.
case kOpCodePong: // We don't support binary frames yet.
default:
return WebSocket::FRAME_ERROR;
}
if (client_frame && !masked) // In Hybi-17 spec client MUST mask its frame.
return WebSocket::FRAME_ERROR;
uint64 payload_length64 = second_byte & kPayloadLengthMask;
if (payload_length64 > kMaxSingleBytePayloadLength) {
int extended_payload_length_size;
if (payload_length64 == kTwoBytePayloadLengthField)
extended_payload_length_size = 2;
else {
DCHECK(payload_length64 == kEightBytePayloadLengthField);
extended_payload_length_size = 8;
}
if (buffer_end - p < extended_payload_length_size)
return WebSocket::FRAME_INCOMPLETE;
payload_length64 = 0;
for (int i = 0; i < extended_payload_length_size; ++i) {
payload_length64 <<= 8;
payload_length64 |= static_cast<unsigned char>(*p++);
}
}
size_t actual_masking_key_length = masked ? kMaskingKeyWidthInBytes : 0;
static const uint64 max_payload_length = 0x7FFFFFFFFFFFFFFFull;
static size_t max_length = std::numeric_limits<size_t>::max();
if (payload_length64 > max_payload_length ||
payload_length64 + actual_masking_key_length > max_length) {
// WebSocket frame length too large.
return WebSocket::FRAME_ERROR;
}
size_t payload_length = static_cast<size_t>(payload_length64);
size_t total_length = actual_masking_key_length + payload_length;
if (static_cast<size_t>(buffer_end - p) < total_length)
return WebSocket::FRAME_INCOMPLETE;
if (masked) {
output->resize(payload_length);
const char* masking_key = p;
char* payload = const_cast<char*>(p + kMaskingKeyWidthInBytes);
for (size_t i = 0; i < payload_length; ++i) // Unmask the payload.
(*output)[i] = payload[i] ^ masking_key[i % kMaskingKeyWidthInBytes];
} else {
output->assign(p, p + payload_length);
}
size_t pos = p + actual_masking_key_length + payload_length - buffer_begin;
*bytes_consumed = pos;
return closed ? WebSocket::FRAME_CLOSE : WebSocket::FRAME_OK;
}
void EncodeFrameHybi17(const std::string& message,
int masking_key,
bool compressed,
std::string* output) {
std::vector<char> frame;
OpCode op_code = kOpCodeText;
size_t data_length = message.length();
int reserved1 = compressed ? kReserved1Bit : 0;
frame.push_back(kFinalBit | op_code | reserved1);
char mask_key_bit = masking_key != 0 ? kMaskBit : 0;
if (data_length <= kMaxSingleBytePayloadLength)
frame.push_back(data_length | mask_key_bit);
else if (data_length <= 0xFFFF) {
frame.push_back(kTwoBytePayloadLengthField | mask_key_bit);
frame.push_back((data_length & 0xFF00) >> 8);
frame.push_back(data_length & 0xFF);
} else {
frame.push_back(kEightBytePayloadLengthField | mask_key_bit);
char extended_payload_length[8];
size_t remaining = data_length;
// Fill the length into extended_payload_length in the network byte order.
for (int i = 0; i < 8; ++i) {
extended_payload_length[7 - i] = remaining & 0xFF;
remaining >>= 8;
}
frame.insert(frame.end(), extended_payload_length,
extended_payload_length + 8);
DCHECK(!remaining);
}
const char* data = const_cast<char*>(message.data());
if (masking_key != 0) {
const char* mask_bytes = reinterpret_cast<char*>(&masking_key);
frame.insert(frame.end(), mask_bytes, mask_bytes + 4);
for (size_t i = 0; i < data_length; ++i) // Mask the payload.
frame.push_back(data[i] ^ mask_bytes[i % kMaskingKeyWidthInBytes]);
} else {
frame.insert(frame.end(), data, data + data_length);
}
*output = std::string(&frame[0], frame.size());
}
} // anonymous namespace
// static
WebSocketEncoder* WebSocketEncoder::CreateServer(
const std::string& request_extensions,
std::string* response_extensions) {
bool deflate;
bool has_client_window_bits;
int client_window_bits;
int server_window_bits;
bool client_no_context_takeover;
bool server_no_context_takeover;
ParseExtensions(request_extensions, &deflate, &has_client_window_bits,
&client_window_bits, &server_window_bits,
&client_no_context_takeover, &server_no_context_takeover);
if (deflate) {
*response_extensions = base::StringPrintf(
"permessage-deflate; server_max_window_bits=%d%s", server_window_bits,
server_no_context_takeover ? "; server_no_context_takeover" : "");
if (has_client_window_bits) {
base::StringAppendF(response_extensions, "; client_max_window_bits=%d",
client_window_bits);
} else {
DCHECK_EQ(client_window_bits, 15);
}
return new WebSocketEncoder(true /* is_server */, server_window_bits,
client_window_bits, server_no_context_takeover);
} else {
*response_extensions = std::string();
return new WebSocketEncoder(true /* is_server */);
}
}
// static
WebSocketEncoder* WebSocketEncoder::CreateClient(
const std::string& response_extensions) {
bool deflate;
bool has_client_window_bits;
int client_window_bits;
int server_window_bits;
bool client_no_context_takeover;
bool server_no_context_takeover;
ParseExtensions(response_extensions, &deflate, &has_client_window_bits,
&client_window_bits, &server_window_bits,
&client_no_context_takeover, &server_no_context_takeover);
if (deflate) {
return new WebSocketEncoder(false /* is_server */, client_window_bits,
server_window_bits, client_no_context_takeover);
} else {
return new WebSocketEncoder(false /* is_server */);
}
}
// static
void WebSocketEncoder::ParseExtensions(const std::string& header_value,
bool* deflate,
bool* has_client_window_bits,
int* client_window_bits,
int* server_window_bits,
bool* client_no_context_takeover,
bool* server_no_context_takeover) {
*deflate = false;
*has_client_window_bits = false;
*client_window_bits = 15;
*server_window_bits = 15;
*client_no_context_takeover = false;
*server_no_context_takeover = false;
if (header_value.empty())
return;
WebSocketExtensionParser parser;
if (!parser.Parse(header_value))
return;
const std::vector<WebSocketExtension>& extensions = parser.extensions();
// TODO(tyoshino): Fail if this method is used for parsing a response and
// there are multiple permessage-deflate extensions or there are any unknown
// extensions.
for (const auto& extension : extensions) {
if (extension.name() != "permessage-deflate") {
continue;
}
const std::vector<WebSocketExtension::Parameter>& parameters =
extension.parameters();
for (const auto& param : parameters) {
const std::string& name = param.name();
// TODO(tyoshino): Fail the connection when an invalid value is given.
if (name == "client_max_window_bits") {
*has_client_window_bits = true;
if (param.HasValue()) {
int bits = 0;
if (base::StringToInt(param.value(), &bits) && bits >= 8 &&
bits <= 15) {
*client_window_bits = bits;
}
}
}
if (name == "server_max_window_bits" && param.HasValue()) {
int bits = 0;
if (base::StringToInt(param.value(), &bits) && bits >= 8 && bits <= 15)
*server_window_bits = bits;
}
if (name == "client_no_context_takeover")
*client_no_context_takeover = true;
if (name == "server_no_context_takeover")
*server_no_context_takeover = true;
}
*deflate = true;
break;
}
}
WebSocketEncoder::WebSocketEncoder(bool is_server) : is_server_(is_server) {
}
WebSocketEncoder::WebSocketEncoder(bool is_server,
int deflate_bits,
int inflate_bits,
bool no_context_takeover)
: is_server_(is_server) {
deflater_.reset(new WebSocketDeflater(
no_context_takeover ? WebSocketDeflater::DO_NOT_TAKE_OVER_CONTEXT
: WebSocketDeflater::TAKE_OVER_CONTEXT));
inflater_.reset(
new WebSocketInflater(kInflaterChunkSize, kInflaterChunkSize));
if (!deflater_->Initialize(deflate_bits) ||
!inflater_->Initialize(inflate_bits)) {
// Disable deflate support.
deflater_.reset();
inflater_.reset();
}
}
WebSocketEncoder::~WebSocketEncoder() {
}
WebSocket::ParseResult WebSocketEncoder::DecodeFrame(
const base::StringPiece& frame,
int* bytes_consumed,
std::string* output) {
bool compressed;
WebSocket::ParseResult result =
DecodeFrameHybi17(frame, is_server_, bytes_consumed, output, &compressed);
if (result == WebSocket::FRAME_OK && compressed) {
if (!Inflate(output))
result = WebSocket::FRAME_ERROR;
}
return result;
}
void WebSocketEncoder::EncodeFrame(const std::string& frame,
int masking_key,
std::string* output) {
std::string compressed;
if (Deflate(frame, &compressed))
EncodeFrameHybi17(compressed, masking_key, true, output);
else
EncodeFrameHybi17(frame, masking_key, false, output);
}
bool WebSocketEncoder::Inflate(std::string* message) {
if (!inflater_)
return false;
if (!inflater_->AddBytes(message->data(), message->length()))
return false;
if (!inflater_->Finish())
return false;
std::vector<char> output;
while (inflater_->CurrentOutputSize() > 0) {
scoped_refptr<IOBufferWithSize> chunk =
inflater_->GetOutput(inflater_->CurrentOutputSize());
if (!chunk.get())
return false;
output.insert(output.end(), chunk->data(), chunk->data() + chunk->size());
}
*message =
output.size() ? std::string(&output[0], output.size()) : std::string();
return true;
}
bool WebSocketEncoder::Deflate(const std::string& message,
std::string* output) {
if (!deflater_)
return false;
if (!deflater_->AddBytes(message.data(), message.length())) {
deflater_->Finish();
return false;
}
if (!deflater_->Finish())
return false;
scoped_refptr<IOBufferWithSize> buffer =
deflater_->GetOutput(deflater_->CurrentOutputSize());
if (!buffer.get())
return false;
*output = std::string(buffer->data(), buffer->size());
return true;
}
} // namespace net
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