/// <summary>
/// Casts the message to <see cref="NetMQMessage"/> with given <paramref name="key"/>,
/// <paramref name="peer"/> and <paramref name="version"/>.
/// </summary>
/// <param name="key">A <see cref="PrivateKey"/> to sign message.</param>
/// <param name="peer"><see cref="Peer"/>-typed representation of the
/// sender's transport layer.
/// <seealso cref="ITransport.AsPeer"/></param>
/// <param name="timestamp">The <see cref="DateTimeOffset"/> of the message is created.
/// </param>
/// <param name="version"><see cref="AppProtocolVersion"/>-typed version of the
/// transport layer.</param>
/// <returns>A <see cref="NetMQMessage"/> containing the signed <see cref="Message"/>.
/// </returns>
/// <exception cref="ArgumentNullException">Thrown when <paramref name="peer"/> is
/// <c>null</c>.</exception>
public NetMQMessage ToNetMQMessage(
PrivateKey key,
Peer peer,
DateTimeOffset timestamp,
AppProtocolVersion version)
{
if (peer is null)
{
throw new ArgumentNullException(nameof(peer));
}
var message = new NetMQMessage();
// Write body (by concrete class)
foreach (NetMQFrame frame in DataFrames)
{
message.Append(frame);
}
// Write headers. (inverse order)
message.Push(timestamp.Ticks);
message.Push(SerializePeer(peer));
message.Push((byte)Type);
message.Push(version.Token);
// Make and insert signature
byte[] signature = key.Sign(message.ToByteArray());
List <NetMQFrame> frames = message.ToList();
frames.Insert((int)MessageFrame.Sign, new NetMQFrame(signature));
message = new NetMQMessage(frames);
if (Identity is byte[] to)
{
message.Push(to);
}
return(message);
}
