void SendPacket(DHCPPacket d) // send
{
IPAddress ipadd = IPAddress.Parse("255.255.255.255");
IPEndPoint ipend = new IPEndPoint(ipadd, 6700);
byte[] send = d.DHCPPacketToBytes();
udpclient.Send(send, send.Length, ipend);
}
void SendPacket(DHCPPacket packet) // Nhan mot goi DHCP packet chuyen thanh dang byte va gui di
{
IPAddress ipadd = IPAddress.Parse("255.255.255.255");
IPEndPoint ipend = new IPEndPoint(ipadd, 6800);
byte[] send = packet.DHCPPacketToBytes();
udpclient.Send(send, send.Length, ipend);
//MessageBox.Show(ByteArrayToString(send));
}
void HandlePacket(DHCPPacket packet)
{
// Xu li khi nhan goi DHCP tu server
byte[] p = new byte[6];
bool d = xid.Contains(ByteArrayToString(packet.xid));
if (!d) // neu xid khong thuoc cac xid da gui
{
return;
}
List <byte[]> Option = packet.optionsplit();
for (int i = 0; i < Option.Count(); i++)
{
if (Option[i][0] == 53) // dhcp messeage type
{
if (Option[i][2] == 2) // xac dinh dhcp offer
{
if (!DHCPServer_IP.SequenceEqual(new byte[] { 0, 0, 0, 0 }))
{
return; // if we already have choose dhcp server, so not doing anything
}
for (int j = 0; j < Option.Count(); j++)
{
if (Option[j][0] == 54) // server dhcp minh da chon
{
for (int z = 0; z < 4; z++)
{
DHCPServer_IP[z] = Option[j][z + 2];
}
offer_saved = packet;
break;
}
}
Send_DHCPRequest(packet, DHCPServer_IP, 1); // gui goi tin request gom goi dhcp offer va dhcp server da chon
}
else if (Option[i][2] == 5) // Xac dinh day la goi dhcp ack
{
FileStream fs;
try
{
fs = new FileStream("IP", FileMode.Create);
byte[] save = offer_saved.DHCPPacketToBytes();
fs.Write(save, 0, save.Length);
fs.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Can not save offer_packet");
}
ip = new IPAddress(packet.yiaddr);
for (int j = 0; j < Option.Count(); j++)
{
if (Option[j][0] == 1)
{
subnetmask = new IPAddress(new byte[] { Option[j][2], Option[j][3], Option[j][4], Option[j][5] });
}
if (Option[j][0] == 3)
{
defaultgateway = new IPAddress(new byte[] { Option[j][2], Option[j][3], Option[j][4], Option[j][5] });
}
if (Option[j][0] == 6)
{
dns = new IPAddress(new byte[] { Option[j][2], Option[j][3], Option[j][4], Option[j][5] });
}
if (Option[j][0] == 51)
{
Int64 epoch = (int)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds;
Int64 leasetime = BitConverter.ToInt32(new byte[] { Option[j][2], Option[j][3], Option[j][4], Option[j][5] }, 0);
time = epoch + leasetime;
t1 = epoch + (int)(leasetime * 0.5);
t2 = epoch + (int)(leasetime * 0.875);
}
}
haveip = true;
}
else // Goi tin DHCP Nak
{
for (int j = 0; j < Option.Count(); j++)
{
if (Option[j][0] == 54) // server dhcp minh da chon
{
for (int z = 0; z < 4; z++)
{
if (DHCPServer_IP[z] != Option[j][z + 2]) // Neu khong phai server dhcp da chon
{
return;
}
}
Send_DHCPDiscover(); // Chuyen ve trang thai requesting
return;
}
}
}
return;
}
}
}
