我正在开发一个应用程序，我想通过DHCP服务器提取一些信息。所以我在端口67 UDP广播上发送DHCPINFORM数据包。我面临的问题是我没有得到响应，即DHCPACK或来自DHCP服务器的任何其他消息，这意味着它有时会一次性发回一个DHCPACK数据包而有些时候根本不回复，这可能是导致此问题的原因？
这是我的网络配置 我的IP：192.168.3.31 DHCP服务器位于：192.168.3.108
我正在使用的和C＃代码是
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");
}
请帮帮我吗？
答案 0 :(得分：1)
我真的不知道问题是什么，但不会更容易使用API，
DHCP客户端API http://msdn.microsoft.com/en-us/library/aa363344(v=VS.85).aspx
DHCP服务器标注API http://msdn.microsoft.com/en-us/library/aa363372(v=VS.85).aspx
答案 1 :(得分：0)
这个问题看起来像是一个简单的操作顺序问题：因为在发送UdpClient之前你没有开始接收DHCPINFORM，服务器可能对你来说太快了<{1}}在绑定端口68之前进入（并被丢弃）。
您应该能够使用单个DHCPACK绑定端口68执行整个事务（发送和接收）。