Adding the message definitions for the remote_security_key STDIO communication classes.

remoting/host/security_key/security_key_message.h

Index: remoting/host/security_key/security_key_message.h
diff --git a/remoting/host/security_key/security_key_message.h b/remoting/host/security_key/security_key_message.h
new file mode 100644
index 0000000000000000000000000000000000000000..4507c1a9c9246b835a94f8c1d89f2e190bedcabe
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+++ b/remoting/host/security_key/security_key_message.h
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+// Copyright 2016 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 REMOTING_HOST_SECURITY_KEY_SECURITY_KEY_MESSAGE_H_
+#define REMOTING_HOST_SECURITY_KEY_SECURITY_KEY_MESSAGE_H_
+
+#include <cstdint>
+#include <string>
+
+#include "base/callback_forward.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace remoting {
+
+// -----------------------------------------------------------------------------
+// Introduction
+// -----------------------------------------------------------------------------
+//
+// This file defines the message format and messages used to interact with the
+// remote_security_key process which is used to forward security key requests
+// to a remote client and return security key responses from the remote client.
+
+// -----------------------------------------------------------------------------
+// Message Format
+// -----------------------------------------------------------------------------
+//
+// {Header: uint32_t}{Control Code: uint8_t}{Payload: optional, variable length}
+//
+// Header: Defines the length of the message (Control Code + Payload).
+//         The header endianness is determined by the platform.
+// Control Code: Contains a value representing the message type.
+// Payload: An optional field of variable length.  Data being represented in
+//          this field is dependent on the message type.
+//          The endianess of the payload is dependent on the message type.
+//          Multi-byte payloads which are part of the security key request and
+//          response messages are expected to be big endian.  The bytes for
+//          these messages will be transmitted across the network as-is.
+//          The format for all other payloads is the endianness of the platform.
+
+// -----------------------------------------------------------------------------
+// Messages
+// -----------------------------------------------------------------------------
+// NOTE: Make sure SecurityKeyMessage::MessageTypeFromValue is updated when new
+//       enum values are added/removed.
+enum class RemoteSecurityKeyMessageType : uint8_t {
+  INVALID = 0,
+
+  // Sent to the remote_security_key process to ask it to establish a
+  // connection to the Chromoting host if a security key enabled session
+  // exists for the current user.
+  // Payload length: 0
+  CONNECT = 1,
+
+  // Sent is sent by the remote_security_key process in response to a
+  // |kConnectToSecurityKeyEnabledSessionMsg| request.
+  // Payload length: 1 byte bool indicating connection state.
+  // True(1): A connection with the Chromoting Host is established and ready
+  //          to receive security key requests to forward.
+  // False(0): No security key session was found.
+  CONNECT_RESPONSE = 2,
+
+  // Sent by the remote_security_key proces when an error occurs while
+  // attempting to detect the existence of a Chromoting session or when
+  // establishing a connection to it.
+  // Payload length: variable.  If > 0 bytes, the bytes represent an error
+  // string which is ascii encoded and does not include a null terminator.
+  CONNECT_ERROR = 3,
+
+  // Sent to the remote_security_key process to ask it to  forward the
+  // security key request payload bytes to the remote machine.
+  // Payload length: > 0 bytes consisting of the security key message to
+  // forward to the remote machine using Length-Value format.
+  REQUEST = 4,
+
+  // Sent by the remote_security_key once a response has been received from
+  // the remote machine.
+  // Payload length: > 0 bytes consisting of the security key response from
+  // the remote machine using Length-Value format.
+  REQUEST_RESPONSE = 5,
+
+  // Sent by the remote_security_key if an error occurs either in sending the
+  // request data to the remote host or when receiving the response.
+  // Payload length: variable.  If > 0 bytes, the bytes represent an error
+  // string which is ascii encoded and does not include a null terminator.
+  REQUEST_ERROR = 6,
+
+  // Sent by the remote_security_key if it receives an unknown command.
+  // Payload length: 0 bytes.
+  UNKNOWN_COMMAND = 254,
+
+  // Sent by the remote_security_key if an error occurs which does not conform
+  // to any existing category.  No response to this message is expected.
+  // Payload length: variable.  If > 0 bytes, the bytes represent an error
+  // string which is ascii encoded and does not include a null terminator.
+  UNKNOWN_ERROR = 255,
+};
+
+class SecurityKeyMessage final {
+ public:
+  // The number of bytes used to represent the header.
+  static const int kHeaderSizeBytes = 4;
+
+  SecurityKeyMessage();
+  ~SecurityKeyMessage();
+
+  // When given a header value (uint32_t), this method will return whether the
+  // length is within the allowable size range.
+  static bool IsValidMessageSize(uint32_t message_size);
+
+  // Returns a RemoteSecurityKeyMessageType enum value corresponding to the
+  // value passed in if it is valid, otherwise INVALID is returned.
+  static RemoteSecurityKeyMessageType MessageTypeFromValue(int value);
+
+  // Parses |message_data| and initializes the internal members.  Returns true
+  // if |message_data| was parsed and the instance was initialized successfully.
+  bool ParseMessage(const std::string& message_data);
+
+  RemoteSecurityKeyMessageType type() { return type_; }
+
+  const std::string& payload() { return payload_; }
+
+ private:
+  RemoteSecurityKeyMessageType type_ = RemoteSecurityKeyMessageType::INVALID;
+  std::string payload_;
+
+  DISALLOW_COPY_AND_ASSIGN(SecurityKeyMessage);
+};
+
+// Used to pass remote security key message data between classes.
+typedef base::Callback<void(scoped_ptr<SecurityKeyMessage> message)>
+    SecurityKeyMessageCallback;
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_SECURITY_KEY_SECURITY_KEY_MESSAGE_H_