/// <summary>处理响应</summary>
/// <param name="session"></param>
/// <param name="request"></param>
/// <param name="response"></param>
protected virtual void Response(INetSession session, DNSEntity request, DNSEntity response)
{
var ss = session?.Session;
if (ss == null)
{
return;
}
var isTcp = ss.Local.IsTcp;
if (OnResponse != null)
{
var e = new DNSEventArgs {
Request = request, Response = response, Session = ss
};
OnResponse(this, e);
}
session?.Send(response.GetStream(isTcp));
}
/// <summary>异步查询解析</summary>
/// <param name="dns"></param>
/// <returns></returns>
public virtual async Task <DNSEntity> QueryAsync(DNSEntity dns)
{
if (!Open())
{
return(null);
}
var nc = Client;
var tcs = new TaskCompletionSource <DNSEntity>();
_recv = tcs;
// 发送请求
var ms = dns.GetStream(nc.Local.IsTcp);
nc.Send(ms.ReadBytes());
Total++;
return(await tcs.Task);
}
internal DNSEntity Invoke(DNSEntity request, Boolean isQuery)
{
var attempts = 0;
while (attempts <= _maxRetryAttemps)
{
var bytes = request.GetStream(false).ReadBytes();
if (bytes.Length > 512)
{
throw new ArgumentException("RFC 1035 2.3.4 states that the maximum size of a UDP datagram is 512 octets (bytes).");
}
Socket socket = null;
try
{
socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp)
{
ReceiveTimeout = 300
};
//socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 300);
socket.SendTo(bytes, bytes.Length, SocketFlags.None, new IPEndPoint(IPAddress.Parse("192.168.178.255"), 137));
if (!isQuery)
{
return(null);
}
// Messages carried by UDP are restricted to 512 bytes (not counting the IP
// or UDP headers). Longer messages are truncated and the TC bit is set in
// the header. (RFC 1035 4.2.1)
var responseMessage = new Byte[512];
//int numBytes = socket.Receive(responseMessage);
var ep = (EndPoint) new IPEndPoint(new IPAddress(4294967295), 137);
var numBytes = socket.ReceiveFrom(responseMessage, ref ep);
if (numBytes == 0 || numBytes > 512)
{
throw new Exception("RFC 1035 2.3.4 states that the maximum size of a UDP datagram is 512 octets (bytes).");
}
//DnsReader br = new DnsReader(responseMessage);
//DnsResponse res = new DnsResponse(br);
var rs = DNSEntity.Read(responseMessage, false);
if (request.Header.ID == rs.Header.ID)
{
return(rs);
}
attempts++;
}
catch
{
attempts++;
}
finally
{
socket.Close();
socket = null;
}
}
throw new Exception("Could not resolve the query (" + attempts + " attempts).");
}