Add cast sender socket factory

This change adds a CastSocket factory for the sender-side which performs
the sender auth challenge and verification before passing a CastSocket
back to the caller.

Bug: openscreen:59
Change-Id: Ibbbdb2b8881e385cc0a8defbe309c7f10a2af323
Reviewed-on: https://chromium-review.googlesource.com/c/openscreen/+/1834457
Commit-Queue: Brandon Tolsch <btolsch@chromium.org>
Reviewed-by: Ryan Keane <rwkeane@google.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/cast/sender/channel/message_util.cc b/cast/sender/channel/message_util.cc
new file mode 100644
index 00000000..ab3ed5d8
--- /dev/null
+++ b/cast/sender/channel/message_util.cc
@@ -0,0 +1,34 @@
+// Copyright 2019 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 "cast/sender/channel/message_util.h"
+
+#include "cast/sender/channel/cast_auth_util.h"
+
+namespace cast {
+namespace channel {
+
+CastMessage CreateAuthChallengeMessage(const AuthContext& auth_context) {
+  CastMessage message;
+  DeviceAuthMessage auth_message;
+
+  AuthChallenge* challenge = auth_message.mutable_challenge();
+  challenge->set_sender_nonce(auth_context.nonce());
+  challenge->set_hash_algorithm(SHA256);
+
+  std::string auth_message_string;
+  auth_message.SerializeToString(&auth_message_string);
+
+  message.set_protocol_version(CastMessage::CASTV2_1_0);
+  message.set_source_id(kPlatformSenderId);
+  message.set_destination_id(kPlatformReceiverId);
+  message.set_namespace_(kAuthNamespace);
+  message.set_payload_type(CastMessage_PayloadType_BINARY);
+  message.set_payload_binary(auth_message_string);
+
+  return message;
+}
+
+}  // namespace channel
+}  // namespace cast