title: Problem in getting DHCPINFORM message response from C#
body: <p>I am developing an application in which I want to pull out some information through the DHCP server. so I am sending a DHCPINFORM packet on port 67 UDP Broadcast. The problem I am facing is that I am not getting response i.e. DHCPACK or anyother message from DHCP server all the times, means some times it send back an DHCPACK packet at once and some time not at all, what might be cause of this issue?</p>
  
  <p>Here is my network configuration
  My IP: 192.168.3.31
  DHCP Server is at: 192.168.3.108</p>
  
  <p>and C# code I am using is as</p>
  
  <pre><code>private void SendDHCPINFORM()
      {
          UdpClient udpClient = new UdpClient();
          IPEndPoint dhcpClientEndpoint = new IPEndPoint(IPAddress.Broadcast, 67);
  
          #region Making Data DHCPINFORM
          D_op = 1;
          D_htype = 1;
          D_hlen = 6;
          D_hops = 0;
          D_xid = new byte[4];
          Random objRandom = new Random(8000);
          objRandom.NextBytes(D_xid);
  
          D_secs = new byte[2];
          D_secs = BitConverter.GetBytes(Convert.ToInt16(0));
  
          D_flags = new byte[2];
          D_flags = BitConverter.GetBytes(Convert.ToInt16(0));
  
          D_ciaddr = new byte[4];
          D_ciaddr[0] = 192;
          D_ciaddr[1] = 168;
          D_ciaddr[2] = 3;
          D_ciaddr[3] = 31;
  
          D_yiaddr = new byte[4];
          D_yiaddr = BitConverter.GetBytes(0);
  
          D_siaddr = new byte[4];
          D_siaddr = BitConverter.GetBytes(0);
  
          D_giaddr = new byte[4];
          D_giaddr = BitConverter.GetBytes(0);
  
          //00-13-D3-D5-27-73
          D_chaddr = new byte[16];
          D_chaddr[0] = 0;
          D_chaddr[1] = 19;
          D_chaddr[2] = 211;
          D_chaddr[3] = 213;
          D_chaddr[4] = 39;
          D_chaddr[5] = 115;
  
          D_sname = new byte[64];
  
  
          D_file = new byte[128];
  
          M_Cookie = new byte[4];
          M_Cookie[0] = 99;
          M_Cookie[1] = 130;
          M_Cookie[2] = 83;
          M_Cookie[3] = 99;
  
  
          D_options = new byte[60];
  
          //Making DHCPINFORM message
          byte[] messageType = new byte[3];
          messageType[0] = 53;
          messageType[1] = 1;
          messageType[2] = 8; //Message Type from 1-8
          Array.Copy(messageType, D_options, messageType.Length);
  
          int options_offset = 3;
  
          byte[] serverIdentifier = new byte[6];
          serverIdentifier[0] = 54;
          serverIdentifier[1] = 4;
          serverIdentifier[2] = 192;
          serverIdentifier[3] = 168;
          serverIdentifier[4] = 3;
          serverIdentifier[5] = 108;
          Array.Copy(serverIdentifier, 0, D_options, options_offset, serverIdentifier.Length);
  
          options_offset += serverIdentifier.Length;
          byte[] dummyPacket = new byte[3];
          dummyPacket[0] = 116;
          dummyPacket[1] = 1;
          dummyPacket[2] = 1;
          Array.Copy(dummyPacket, 0, D_options, options_offset, dummyPacket.Length);
  
          options_offset += dummyPacket.Length;
          byte[] clientIdentifier = new byte[9];
          clientIdentifier[0] = 61;
          clientIdentifier[1] = 7;
          clientIdentifier[2] = 1;
          Array.Copy(D_chaddr, 0, clientIdentifier, 3, 6);
          Array.Copy(clientIdentifier, 0, D_options, options_offset, clientIdentifier.Length);
  
          options_offset += clientIdentifier.Length;
          byte[] hostName = new byte[7];
          hostName[0] = 12;
          hostName[1] = 5;
          Array.Copy(Encoding.ASCII.GetBytes("host1"), 0, hostName, 2, Encoding.ASCII.GetBytes("host1").Length);
          Array.Copy(hostName, 0, D_options, options_offset, hostName.Length);
  
          options_offset += hostName.Length;
          byte[] vendorClassID = new byte[10];
          vendorClassID[0] = 60;
          vendorClassID[1] = 8;
          //Array.Copy(Encoding.ASCII.GetBytes("Unspecified"), 0, vendorClassID, 2, Encoding.ASCII.GetBytes("Unspecified").Length);
          Array.Copy(Encoding.ASCII.GetBytes("MSFT 5.0"), 0, vendorClassID, 2, Encoding.ASCII.GetBytes("MSFT 5.0").Length);
          Array.Copy(vendorClassID, 0, D_options, options_offset, vendorClassID.Length);
  
          options_offset += vendorClassID.Length;
          byte[] paramRequestList = new byte[13];
          paramRequestList[0] = 55;
          paramRequestList[1] = 11;
          paramRequestList[2] = 1;
          paramRequestList[3] = 15;
          paramRequestList[4] = 3;
          paramRequestList[5] = 6;
          paramRequestList[6] = 44;
          paramRequestList[7] = 46;
          paramRequestList[8] = 47;
          paramRequestList[9] = 31;
          paramRequestList[10] = 33;
          paramRequestList[11] = 249;
          paramRequestList[12] = 43;
          //Array.Copy(paramRequestList, 0, D_options, 31, paramRequestList.Length);
          Array.Copy(paramRequestList, 0, D_options, options_offset, paramRequestList.Length);
  
          options_offset += paramRequestList.Length;
          byte[] vendorSpecificInfo = new byte[5];
          vendorSpecificInfo[0] = 43;
          vendorSpecificInfo[1] = 2;
          vendorSpecificInfo[2] = 220;
          vendorSpecificInfo[3] = 0;
          vendorSpecificInfo[4] = 255;
          Array.Copy(vendorSpecificInfo, 0, D_options, options_offset, vendorSpecificInfo.Length);
  
          byte[] dhcpMessage = new byte[300];
          dhcpMessage[0] = D_op;
          dhcpMessage[1] = D_htype;
          dhcpMessage[2] = D_hlen;
          dhcpMessage[3] = D_hops;
  
          int destinationIndex = 4;
          Array.Copy(D_xid, 0, dhcpMessage, destinationIndex, D_xid.Length);
  
          destinationIndex = destinationIndex + D_xid.Length;
          Array.Copy(D_secs, 0, dhcpMessage, destinationIndex, D_secs.Length);
  
          destinationIndex = destinationIndex + D_secs.Length;
          Array.Copy(D_flags, 0, dhcpMessage, destinationIndex, D_flags.Length);
  
          destinationIndex = destinationIndex + D_flags.Length;
          Array.Copy(D_ciaddr, 0, dhcpMessage, destinationIndex, D_ciaddr.Length);
  
          destinationIndex = destinationIndex + D_ciaddr.Length;
          Array.Copy(D_yiaddr, 0, dhcpMessage, destinationIndex, D_yiaddr.Length);
  
          destinationIndex = destinationIndex + D_yiaddr.Length;
          Array.Copy(D_siaddr, 0, dhcpMessage, destinationIndex, D_siaddr.Length);
  
          destinationIndex = destinationIndex + D_siaddr.Length;
          Array.Copy(D_giaddr, 0, dhcpMessage, destinationIndex, D_giaddr.Length);
  
          destinationIndex = destinationIndex + D_giaddr.Length;
          Array.Copy(D_chaddr, 0, dhcpMessage, destinationIndex, D_chaddr.Length);
  
          destinationIndex = destinationIndex + D_chaddr.Length;
          Array.Copy(D_sname, 0, dhcpMessage, destinationIndex, D_sname.Length);
  
          destinationIndex = destinationIndex + D_sname.Length;
          Array.Copy(D_file, 0, dhcpMessage, destinationIndex, D_file.Length);
  
          destinationIndex = destinationIndex + D_file.Length;
          Array.Copy(M_Cookie, 0, dhcpMessage, destinationIndex, M_Cookie.Length);
  
          destinationIndex = destinationIndex + M_Cookie.Length;
          Array.Copy(D_options, 0, dhcpMessage, destinationIndex, D_options.Length);
          #endregion
  
          udpClient.Send(dhcpMessage, 300, dhcpClientEndpoint);
  
          UdpClient udpServerResponse = new UdpClient(68);
          IPEndPoint dhcpServerEndPoint = new IPEndPoint(IPAddress.Any, 0);
  
          //The following line is receiving the response from DHCP server
          //works some time immediately and some time not even after couple 
          //of minutes and program goes to halt state? Am I making some mistake?
          byte[] dataReceived = udpServerResponse.Receive(ref dhcpServerEndPoint);
  
          Console.WriteLine("Message Received");
      }
  </code></pre>
  
  <p>Please help me out?</p>