/// <summary>
/// Function that sends the async responses to the client.
/// </summary>
/// <param name="endpoint">The endpoint to send the response to</param>
/// <param name="type">Packet type</param>
/// <param name="record">The DNSRecord to send back</param>
/// <returns></returns>
private bool SendResponse(EndPoint endpoint, DNSPacket.LookupType type, DNSRecord record)
{
if (record == null)
{
return(false);
}
DNSPacket packet = new DNSPacket
{
Type = DNSPacket.PacketType.Response,
Lookup = type,
Data = (type == DNSPacket.LookupType.Name)
? Encoding.ASCII.GetBytes(record.Address)
: Encoding.ASCII.GetBytes(string.Join(",", record.SubDomains.Select(n => n.Domain)).ToCharArray(), 0, 254)
};
packet.Length = packet.Data.Length;
byte[] sendBuffer = DNSPacket.PacketToRaw(packet);
try
{
Server.BeginSendTo(sendBuffer, 0, sendBuffer.Length, SocketFlags.None, endpoint, new AsyncCallback(ResponseCompleted), endpoint);
return(true);
}
catch (Exception ex)
{
ErrorLog?.Invoke($"Error sending async response: '{ex.Message}'.");
return(false);
}
}
/// <summary>
/// Connects with the provided DNS Server and retrieves the DNS name by looking up the given IP.
/// </summary>
/// <param name="ipadd">the ip address you want a DNS name for.</param>
/// <returns></returns>
public string RetrieveDNSName(string ipadd)
{
Connect();
DNSPacket packet = new DNSPacket
{
Type = DNSPacket.PacketType.Request,
Lookup = DNSPacket.LookupType.ARPA,
Data = Encoding.ASCII.GetBytes(ipadd)
};
packet.Length = packet.Data.Length;
byte[] raw = DNSPacket.PacketToRaw(packet);
Client.Send(raw, packet.Length + 3);
IPEndPoint ipep = new IPEndPoint(IPAddress.Parse(Address), 51);
byte[] answer = Client.Receive(ref ipep);
string responseData;
if (answer.Length != 0 && ipep.Address.ToString().Equals(Address))
{
//checks if the response came from the DNS server
DNSPacket response = DNSPacket.RawToPacket(answer);
if (response.Type == DNSPacket.PacketType.Response && response.Lookup == DNSPacket.LookupType.ARPA)
{
responseData = Encoding.ASCII.GetString(response.Data, 0, response.Length);
}
else
{
throw new DNSException(response, "Expected a Response and Name type, got something else.");
}
}
else
{
throw new DNSException(null, "Received empty response or the response came from the wrong host.");
}
Disconnect();
return(responseData);
}