Introduce WebSocketDeflateParameters.

net/websockets/websocket_deflate_parameters.cc

+// Copyright 2015 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/websockets/websocket_deflate_parameters.h"
+
+#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;
+
+const char kServerNoContextTakeOver[] = "server_no_context_takeover";
+const char kClientNoContextTakeOver[] = "client_no_context_takeover";
+const char kServerMaxWindowBits[] = "server_max_window_bits";
+const char kClientMaxWindowBits[] = "client_max_window_bits";
+const 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::IntToString(server_max_window_bits())));
+  }
+  if (is_client_max_window_bits_specified()) {
+    if (has_client_max_window_bits_value()) {
+      e.Add(WebSocketExtension::Parameter(
+          kClientMaxWindowBits, base::IntToString(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