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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/websockets/websocket_deflate_parameters.h"
#include <vector> // for iterating over extension.parameters()
#include "base/strings/string_number_conversions.h"
namespace net {
namespace {
const WebSocketDeflater::ContextTakeOverMode kTakeOverContext =
WebSocketDeflater::TAKE_OVER_CONTEXT;
const WebSocketDeflater::ContextTakeOverMode kDoNotTakeOverContext =
WebSocketDeflater::DO_NOT_TAKE_OVER_CONTEXT;
constexpr char kServerNoContextTakeOver[] = "server_no_context_takeover";
constexpr char kClientNoContextTakeOver[] = "client_no_context_takeover";
constexpr char kServerMaxWindowBits[] = "server_max_window_bits";
constexpr char kClientMaxWindowBits[] = "client_max_window_bits";
constexpr char kExtensionName[] = "permessage-deflate";
bool GetWindowBits(const std::string& value, int* window_bits) {
return !value.empty() && value[0] != '0' &&
value.find_first_not_of("0123456789") == std::string::npos &&
base::StringToInt(value, window_bits);
}
bool DuplicateError(const std::string& name, std::string* failure_message) {
*failure_message =
"Received duplicate permessage-deflate extension parameter " + name;
return false;
}
bool InvalidError(const std::string& name, std::string* failure_message) {
*failure_message = "Received invalid " + name + " parameter";
return false;
}
} // namespace
WebSocketExtension WebSocketDeflateParameters::AsExtension() const {
WebSocketExtension e(kExtensionName);
if (server_context_take_over_mode_ == kDoNotTakeOverContext)
e.Add(WebSocketExtension::Parameter(kServerNoContextTakeOver));
if (client_context_take_over_mode_ == kDoNotTakeOverContext)
e.Add(WebSocketExtension::Parameter(kClientNoContextTakeOver));
if (is_server_max_window_bits_specified()) {
DCHECK(server_max_window_bits_.has_value);
e.Add(WebSocketExtension::Parameter(
kServerMaxWindowBits, base::NumberToString(server_max_window_bits())));
}
if (is_client_max_window_bits_specified()) {
if (has_client_max_window_bits_value()) {
e.Add(WebSocketExtension::Parameter(
kClientMaxWindowBits,
base::NumberToString(client_max_window_bits())));
} else {
e.Add(WebSocketExtension::Parameter(kClientMaxWindowBits));
}
}
return e;
}
bool WebSocketDeflateParameters::IsValidAsRequest(std::string*) const {
if (server_max_window_bits_.is_specified) {
DCHECK(server_max_window_bits_.has_value);
DCHECK(IsValidWindowBits(server_max_window_bits_.bits));
}
if (client_max_window_bits_.is_specified &&
client_max_window_bits_.has_value) {
DCHECK(IsValidWindowBits(client_max_window_bits_.bits));
}
return true;
}
bool WebSocketDeflateParameters::IsValidAsResponse(
std::string* failure_message) const {
if (server_max_window_bits_.is_specified) {
DCHECK(server_max_window_bits_.has_value);
DCHECK(IsValidWindowBits(server_max_window_bits_.bits));
}
if (client_max_window_bits_.is_specified) {
if (!client_max_window_bits_.has_value) {
*failure_message = "client_max_window_bits must have value";
return false;
}
DCHECK(IsValidWindowBits(client_max_window_bits_.bits));
}
return true;
}
bool WebSocketDeflateParameters::Initialize(const WebSocketExtension& extension,
std::string* failure_message) {
*this = WebSocketDeflateParameters();
if (extension.name() != kExtensionName) {
*failure_message = "extension name doesn't match";
return false;
}
for (const auto& p : extension.parameters()) {
if (p.name() == kServerNoContextTakeOver) {
if (server_context_take_over_mode() == kDoNotTakeOverContext)
return DuplicateError(p.name(), failure_message);
if (p.HasValue())
return InvalidError(p.name(), failure_message);
SetServerNoContextTakeOver();
} else if (p.name() == kClientNoContextTakeOver) {
if (client_context_take_over_mode() == kDoNotTakeOverContext)
return DuplicateError(p.name(), failure_message);
if (p.HasValue())
return InvalidError(p.name(), failure_message);
SetClientNoContextTakeOver();
} else if (p.name() == kServerMaxWindowBits) {
if (server_max_window_bits_.is_specified)
return DuplicateError(p.name(), failure_message);
int bits;
if (!GetWindowBits(p.value(), &bits) || !IsValidWindowBits(bits))
return InvalidError(p.name(), failure_message);
SetServerMaxWindowBits(bits);
} else if (p.name() == kClientMaxWindowBits) {
if (client_max_window_bits_.is_specified)
return DuplicateError(p.name(), failure_message);
if (p.value().empty()) {
SetClientMaxWindowBits();
} else {
int bits;
if (!GetWindowBits(p.value(), &bits) || !IsValidWindowBits(bits))
return InvalidError(p.name(), failure_message);
SetClientMaxWindowBits(bits);
}
} else {
*failure_message =
"Received an unexpected permessage-deflate extension parameter";
return false;
}
}
return true;
}
bool WebSocketDeflateParameters::IsCompatibleWith(
const WebSocketDeflateParameters& response) const {
const auto& request = *this;
DCHECK(request.IsValidAsRequest());
DCHECK(response.IsValidAsResponse());
// server_no_context_take_over
if (request.server_context_take_over_mode() == kDoNotTakeOverContext &&
response.server_context_take_over_mode() == kTakeOverContext) {
return false;
}
// No compatibility check is needed for client_no_context_take_over
// server_max_window_bits
if (request.server_max_window_bits_.is_specified) {
DCHECK(request.server_max_window_bits_.has_value);
if (!response.server_max_window_bits_.is_specified)
return false;
DCHECK(response.server_max_window_bits_.has_value);
if (request.server_max_window_bits_.bits <
response.server_max_window_bits_.bits) {
return false;
}
}
// client_max_window_bits
if (!request.client_max_window_bits_.is_specified &&
response.client_max_window_bits_.is_specified) {
return false;
}
return true;
}
} // namespace net
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