/// <summary>
/// Sends a DNS Request
/// </summary>
/// <param name="OpCode">OpCode</param>
/// <param name="Recursive">If recursive evaluation is desired.
/// (Recursive evaluation is optional on behalf of the DNS server.</param>
/// <param name="Questions">Questions</param>
/// <param name="Destination">Destination. If null, default destination is assumed.</param>
/// <param name="Callback">Method to call when response is returned.</param>
/// <param name="State">State object to pass on to callback method.</param>
public void SendRequest(OpCode OpCode, bool Recursive, Question[] Questions,
IPEndPoint Destination, DnsMessageEventHandler Callback, object State)
{
using (MemoryStream Request = new MemoryStream())
{
ushort ID = DnsResolver.NextID;
DnsClient.WriteUInt16(ID, Request);
byte b = (byte)((int)OpCode << 3);
if (Recursive)
{
b |= 1;
}
Request.WriteByte(b);
Request.WriteByte((byte)RCode.NoError);
int c = Questions.Length;
if (c == 0)
{
throw new ArgumentException("No questions included in request.", nameof(Questions));
}
if (c > ushort.MaxValue)
{
throw new ArgumentException("Too many questions in request.", nameof(Questions));
}
DnsClient.WriteUInt16((ushort)c, Request); // Query Count
DnsClient.WriteUInt16(0, Request); // Answer Count
DnsClient.WriteUInt16(0, Request); // Authoritative Count
DnsClient.WriteUInt16(0, Request); // Additional Count
Dictionary <string, ushort> NamePositions = new Dictionary <string, ushort>();
foreach (Question Q in Questions)
{
DnsClient.WriteName(Q.QNAME, Request, NamePositions);
DnsClient.WriteUInt16((ushort)Q.QTYPE, Request);
DnsClient.WriteUInt16((ushort)Q.QCLASS, Request);
}
byte[] Packet = Request.ToArray();
this.BeginTransmit(ID, Packet, Destination, Callback, State);
}
}
/// <summary>
/// Sends a message to a DNS server.
/// </summary>
/// <param name="ID">Message ID</param>
/// <param name="Message">Encoded message</param>
/// <param name="Destination">Destination. If null, default destination is assumed.</param>
/// <param name="Callback">method to call when a response is returned.</param>
/// <param name="State">State object to pass on to callback method.</param>
protected async void BeginTransmit(ushort ID, byte[] Message, IPEndPoint Destination, DnsMessageEventHandler Callback, object State)
{
if (this.disposed)
{
return;
}
if (!(Callback is null))
{
Rec Rec = new Rec()
{
ID = ID,
Output = Message,
Destination = Destination,
Callback = Callback,
State = State
};
lock (this.outgoingMessages)
{
this.outgoingMessages[ID] = Rec;
}
this.scheduler.Add(DateTime.Now.AddSeconds(2), this.CheckRetry, Rec);
}
lock (this.outputQueue)
{
if (this.isWriting)
{
this.outputQueue.AddLast(new KeyValuePair <byte[], IPEndPoint>(Message, Destination));
return;
}
else
{
this.isWriting = true;
}
}
try
{
while (Message != null)
{
this.TransmitBinary(Message);
await this.SendAsync(Message, Destination);
if (this.disposed)
{
return;
}
lock (this.outputQueue)
{
if (this.outputQueue.First is null)
{
this.isWriting = false;
Message = null;
}
else
{
Message = this.outputQueue.First.Value.Key;
Destination = this.outputQueue.First.Value.Value;
this.outputQueue.RemoveFirst();
}
}
}
}
catch (Exception ex)
{
this.Error(ex.Message);
}
}
/// <summary>
/// Execute a DNS query.
/// </summary>
/// <param name="Questions">Questions</param>
/// <param name="Destination">Destination. If null, default destination is assumed.</param>
/// <param name="Callback">Method to call when response is returned.</param>
/// <param name="State">State object to pass on to callback method.</param>
public void Query(Question[] Questions, IPEndPoint Destination, DnsMessageEventHandler Callback, object State)
{
this.SendRequest(OpCode.Query, false, Questions, Destination, Callback, State);
}
/// <summary>
/// Execute a DNS query.
/// </summary>
/// <param name="QNAME">Query Name</param>
/// <param name="QTYPEs">Query Types</param>
/// <param name="QCLASS">Query Class</param>
/// <param name="Destination">Destination. If null, default destination is assumed.</param>
/// <param name="Callback">Method to call when response is returned.</param>
/// <param name="State">State object to pass on to callback method.</param>
public void Query(string QNAME, QTYPE[] QTYPEs, QCLASS QCLASS, IPEndPoint Destination, DnsMessageEventHandler Callback, object State)
{
this.Query(ToQuestions(QNAME, QTYPEs, QCLASS), Destination, Callback, State);
}
/// <summary>
/// Execute a DNS query.
/// </summary>
/// <param name="QNAME">Query Name</param>
/// <param name="QTYPE">Query Type</param>
/// <param name="QCLASS">Query Class</param>
/// <param name="Destination">Destination. If null, default destination is assumed.</param>
/// <param name="Callback">Method to call when response is returned.</param>
/// <param name="State">State object to pass on to callback method.</param>
public void Query(string QNAME, QTYPE QTYPE, QCLASS QCLASS, IPEndPoint Destination, DnsMessageEventHandler Callback, object State)
{
this.Query(new Question[] { new Question(QNAME, QTYPE, QCLASS) }, Destination, Callback, State);
}
