/// <summary>
/// Called by the MulticastClient when a DNS message is received.
/// </summary>
/// <param name="sender">
/// The <see cref="MulticastClient"/> that got the message.
/// </param>
/// <param name="result">
/// The received message <see cref="UdpReceiveResult"/>.
/// </param>
/// <remarks>
/// Decodes the <paramref name="result"/> and then raises
/// either the <see cref="QueryReceived"/> or <see cref="AnswerReceived"/> event.
/// <para>
/// Multicast DNS messages received with an OPCODE or RCODE other than zero
/// are silently ignored.
/// </para>
/// <para>
/// If the message cannot be decoded, then the <see cref="MalformedMessage"/>
/// event is raised.
/// </para>
/// </remarks>
public void OnDnsMessage(object sender, UdpReceiveResult result)
{
// If recently received, then ignore.
// A message has been recently received, if its content, as well as the remote endpoint(!) match, otherwise messages from different senders can be considered equal.
var receivedMessage = new byte[result.Buffer.Length + result.RemoteEndPoint.Address.GetAddressBytes().Length];
result.Buffer.CopyTo(receivedMessage, 0);
result.RemoteEndPoint.Address.GetAddressBytes().CopyTo(receivedMessage, result.Buffer.Length);
if (IgnoreDuplicateMessages && !receivedMessages.TryAdd(receivedMessage))
{
// Not continuing here because it looks like a duplicate message
return;
}
var msg = new Message();
try
{
msg.Read(result.Buffer, 0, result.Buffer.Length);
}
catch (Exception e)
{
log.Warn("Received malformed message", e);
MalformedMessage?.Invoke(this, result.Buffer);
return; // eat the exception
}
if (msg.Opcode != MessageOperation.Query || msg.Status != MessageStatus.NoError)
{
return;
}
// Dispatch the message.
try
{
if (msg.IsQuery && msg.Questions.Count > 0)
{
QueryReceived?.Invoke(this, new MessageEventArgs {
Message = msg, RemoteEndPoint = result.RemoteEndPoint
});
}
else if (msg.IsResponse && msg.Answers.Count > 0)
{
AnswerReceived?.Invoke(this, new MessageEventArgs {
Message = msg, RemoteEndPoint = result.RemoteEndPoint
});
}
}
catch (Exception e)
{
log.Error("Receive handler failed", e);
// eat the exception
}
}
/// <summary>
/// Called by the MulticastClient when a DNS message is received.
/// </summary>
/// <param name="sender">
/// The <see cref="MulticastClient"/> that got the message.
/// </param>
/// <param name="result">
/// The received message <see cref="UdpReceiveResult"/>.
/// </param>
/// <remarks>
/// Decodes the <paramref name="result"/> and then raises
/// either the <see cref="QueryReceived"/> or <see cref="AnswerReceived"/> event.
/// <para>
/// Multicast DNS messages received with an OPCODE or RCODE other than zero
/// are silently ignored.
/// </para>
/// <para>
/// If the message cannot be decoded, then the <see cref="MalformedMessage"/>
/// event is raised.
/// </para>
/// </remarks>
public void OnDnsMessage(object sender, UdpReceiveResult result)
{
// If recently received, then ignore.
if (IgnoreDuplicateMessages && !_receivedMessages.TryAdd(result.Buffer))
{
return;
}
if (GetLinkLocalAddresses().Any(a => a == result.RemoteEndPoint.Address))
{
return;
}
var msg = new Message();
try
{
msg.Read(result.Buffer, 0, result.Buffer.Length);
}
catch (Exception e)
{
Log.LogWarning("Received malformed message", e);
MalformedMessage?.Invoke(this, result.Buffer);
return; // eat the exception
}
if (msg.Opcode != MessageOperation.Query || msg.Status != MessageStatus.NoError)
{
return;
}
// Dispatch the message.
try
{
if (msg.IsQuery && msg.Questions.Count > 0)
{
QueryReceived?.Invoke(this, new MessageEventArgs {
Message = msg, RemoteEndPoint = result.RemoteEndPoint
});
}
else if (msg.IsResponse && msg.Answers.Count > 0)
{
AnswerReceived?.Invoke(this, new MessageEventArgs {
Message = msg, RemoteEndPoint = result.RemoteEndPoint
});
}
}
catch (Exception e)
{
Log.LogError("Receive handler failed", e);
// eat the exception
}
}
/// <summary>
/// Called by the MulticastClient when a DNS message is received.
/// </summary>
/// <param name="sender">
/// The <see cref="MulticastClient"/> that got the message.
/// </param>
/// <param name="result">
/// The received message <see cref="UdpReceiveResult"/>.
/// </param>
/// <remarks>
/// Decodes the <paramref name="result"/> and then raises
/// either the <see cref="QueryReceived"/> or <see cref="AnswerReceived"/> event.
/// <para>
/// Multicast DNS messages received with an OPCODE or RCODE other than zero
/// are silently ignored.
/// </para>
/// <para>
/// If the message cannot be decoded, then the <see cref="MalformedMessage"/>
/// event is raised.
/// </para>
/// </remarks>
public void OnDnsMessage(object sender, UdpReceiveResult result)
{
// If recently received, then ignore.
if (IgnoreDuplicateMessages && !receivedMessages.TryAdd(result.Buffer))
{
return;
}
var msg = new Message();
try
{
msg.Read(result.Buffer, 0, result.Buffer.Length);
}
catch (Exception e)
{
System.Diagnostics.Trace.TraceWarning($"Received malformed message : {e.GetBaseException().Message}");
MalformedMessage?.Invoke(this, result.Buffer);
return; // eat the exception
}
if (msg.Opcode != MessageOperation.Query || msg.Status != MessageStatus.NoError)
{
return;
}
// Dispatch the message.
try
{
if (msg.IsQuery && msg.Questions.Count > 0)
{
QueryReceived?.Invoke(this, new MessageEventArgs {
Message = msg, RemoteEndPoint = result.RemoteEndPoint
});
}
else if (msg.IsResponse && msg.Answers.Count > 0)
{
AnswerReceived?.Invoke(this, new MessageEventArgs {
Message = msg, RemoteEndPoint = result.RemoteEndPoint
});
}
}
catch (Exception e)
{
System.Diagnostics.Trace.TraceError($"Receive handler failed {e.GetBaseException().Message}");
// eat the exception
}
}