Introduce WebSocketDeflateParameters.

net/websockets/websocket_deflate_parameters.h

+// 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.
+
+#ifndef NET_WEBSOCKETS_WEBSOCKET_DEFLATE_PARAMETERS_H_
+#define NET_WEBSOCKETS_WEBSOCKET_DEFLATE_PARAMETERS_H_
+
+#include <stdint.h>
+#include <string>
+
+#include "base/logging.h"
+#include "net/base/net_export.h"
+#include "net/websockets/websocket_deflater.h"
+#include "net/websockets/websocket_extension.h"
+
+namespace net {
+
+// A WebSocketDeflateParameters represents permessage-deflate extension
+// parameters. This class is used either for request and response.
+class NET_EXPORT_PRIVATE WebSocketDeflateParameters {
+ public:
+  using ContextTakeOverMode = WebSocketDeflater::ContextTakeOverMode;
+
+  // Returns a WebSocketExtension instance containing the parameters stored in
+  // this object.
+  WebSocketExtension AsExtension() const;
+
+  // Returns true when succeeded.
+  // Returns false and stores the failure message to |failure_message|
+  // otherwise.
+  // Note that even if this function succeeds it is not guaranteed that the
+  // object is valid. To check it, call IsValidAsRequest or IsValidAsResponse.
+  bool Initialize(const WebSocketExtension& input,
+                  std::string* failure_message);
+
+  // Returns true when |*this| and |response| are compatible.
+  // |*this| must be valid as a request and |response| must be valid as a
+  // response.
+  bool IsCompatibleWith(const WebSocketDeflateParameters& response) const;
+
+  bool IsValidAsRequest(std::string* failure_message) const;
+  bool IsValidAsResponse(std::string* failure_message) const;
+  bool IsValidAsRequest() const {
+    std::string message;
+    return IsValidAsRequest(&message);
+  }
+  bool IsValidAsResponse() const {
+    std::string message;
+    return IsValidAsResponse(&message);
+  }
+
+  ContextTakeOverMode server_context_take_over_mode() const {
+    return server_context_take_over_mode_;
+  }
+  ContextTakeOverMode client_context_take_over_mode() const {
+    return client_context_take_over_mode_;
+  }
+  bool is_server_max_window_bits_specified() const {
+    return server_max_window_bits_.is_specified;
+  }
+  int server_max_window_bits() const {
+    DCHECK(is_server_max_window_bits_specified());
+    return server_max_window_bits_.bits;
+  }
+  bool is_client_max_window_bits_specified() const {
+    return client_max_window_bits_.is_specified;
+  }
+  bool has_client_max_window_bits_value() const {
+    DCHECK(is_client_max_window_bits_specified());
+    return client_max_window_bits_.has_value;
+  }
+  int client_max_window_bits() const {
+    DCHECK(has_client_max_window_bits_value());
+    return client_max_window_bits_.bits;
+  }
+  void SetServerNoContextTakeOver() {
+    server_context_take_over_mode_ =
+        WebSocketDeflater::DO_NOT_TAKE_OVER_CONTEXT;
+  }
+  void SetClientNoContextTakeOver() {
+    client_context_take_over_mode_ =
+        WebSocketDeflater::DO_NOT_TAKE_OVER_CONTEXT;
+  }
+  // |bits| must be valid as a max_window_bits value.
+  void SetServerMaxWindowBits(int bits) {
+    DCHECK(IsValidWindowBits(bits));
+    server_max_window_bits_ = WindowBits(bits, true, true);
+  }
+  void SetClientMaxWindowBits() {
+    client_max_window_bits_ = WindowBits(0, true, false);
+  }
+  // |bits| must be valid as a max_window_bits value.
+  void SetClientMaxWindowBits(int bits) {
+    DCHECK(IsValidWindowBits(bits));
+    client_max_window_bits_ = WindowBits(bits, true, true);
+  }
+
+  // Return true if |bits| is valid as a max_window_bits value.
+  static bool IsValidWindowBits(int bits) { return 8 <= bits && bits <= 15; }
+
+ private:
+  struct WindowBits {
+    WindowBits() : WindowBits(0, false, false) {}
+    WindowBits(int16_t bits, bool is_specified, bool has_value)
+        : bits(bits), is_specified(is_specified), has_value(has_value) {}
+
+    int16_t bits;
+    // True when "window bits" parameter appears in the parameters.
+    bool is_specified;
+    // True when "window bits" parameter has the value.
+    bool has_value;
+  };
+
+  // |server_context_take_over_mode| is set to DO_NOT_TAKE_OVER_CONTEXT if and
+  // only if |server_no_context_takeover| is set in the parameters.
+  ContextTakeOverMode server_context_take_over_mode_ =
+      WebSocketDeflater::TAKE_OVER_CONTEXT;
+  // |client_context_take_over_mode| is set to DO_NOT_TAKE_OVER_CONTEXT if and
+  // only if |client_no_context_takeover| is set in the parameters.
+  ContextTakeOverMode client_context_take_over_mode_ =
+      WebSocketDeflater::TAKE_OVER_CONTEXT;
+  WindowBits server_max_window_bits_;
+  WindowBits client_max_window_bits_;
+};
+
+}  // namespace net
+
+#endif  // NET_WEBSOCKETS_WEBSOCKET_DEFLATE_PARAMETERS_H_