Adding the message definitions for the remote_security_key STDIO communication classes.

remoting/host/security_key/security_key_message.cc

Index: remoting/host/security_key/security_key_message.cc
diff --git a/remoting/host/security_key/security_key_message.cc b/remoting/host/security_key/security_key_message.cc
new file mode 100644
index 0000000000000000000000000000000000000000..95556e5d1f864749b89bce776ce9fe72135b0a97
--- /dev/null
+++ b/remoting/host/security_key/security_key_message.cc
@@ -0,0 +1,69 @@
+// 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.
+
+#include "remoting/host/security_key/security_key_message.h"
+
+#include "base/logging.h"
+
+namespace {
+
+// Limit remote security key messages to 256KB.
+const uint32_t kMaxSecurityKeyMessageByteCount = 256 * 1024;
+
+const int kRemoteSecurityKeyMessageControlCodeByteCount = 1;
+
+}  // namespace
+
+namespace remoting {
+
+SecurityKeyMessage::SecurityKeyMessage() {}
+
+SecurityKeyMessage::~SecurityKeyMessage() {}
+
+bool SecurityKeyMessage::IsValidMessageSize(uint32_t message_size) {
+  return message_size > 0 && message_size <= kMaxSecurityKeyMessageByteCount;
+}
+
+RemoteSecurityKeyMessageType SecurityKeyMessage::MessageTypeFromValue(
+    int value) {
+  // Note: The static_cast from enum value to int should be safe since the enum
+  // type is an unsigned 8bit value.
+  switch (value) {
+    case static_cast<int>(RemoteSecurityKeyMessageType::CONNECT):
+    case static_cast<int>(RemoteSecurityKeyMessageType::CONNECT_RESPONSE):
+    case static_cast<int>(RemoteSecurityKeyMessageType::CONNECT_ERROR):
+    case static_cast<int>(RemoteSecurityKeyMessageType::REQUEST):
+    case static_cast<int>(RemoteSecurityKeyMessageType::REQUEST_RESPONSE):
+    case static_cast<int>(RemoteSecurityKeyMessageType::REQUEST_ERROR):
+    case static_cast<int>(RemoteSecurityKeyMessageType::UNKNOWN_COMMAND):
+    case static_cast<int>(RemoteSecurityKeyMessageType::UNKNOWN_ERROR):
+    case static_cast<int>(RemoteSecurityKeyMessageType::INVALID):
+      return static_cast<RemoteSecurityKeyMessageType>(value);
+
+    default:
+      LOG(ERROR) << "Unknown message type passed in: " << value;
+      return RemoteSecurityKeyMessageType::INVALID;
+  }
+}
+
+bool SecurityKeyMessage::ParseMessage(const std::string& message_data) {
+  if (!IsValidMessageSize(message_data.size())) {
+    return false;
+  }
+
+  // The first char of the message is the message type.
+  type_ = MessageTypeFromValue(message_data[0]);
+  if (type_ == RemoteSecurityKeyMessageType::INVALID) {
+    return false;
+  }
+
+  payload_.clear();
+  if (message_data.size() > kRemoteSecurityKeyMessageControlCodeByteCount) {
+    payload_ = message_data.substr(1);
+  }
+
+  return true;
+}
+
+}  // namespace remoting