void DisplayPacket(DHCPPacket packet) // hien thi goi tin vua nhan ra man hinh
{
// Hien thi goi tin dhcp vua nhan duoc len man hinh
//rtb_DHCPMessage.Text += packet.ToText() + "\r\n";
List <byte[]> Option = packet.optionsplit();
string DHCPType = "";
for (int i = 0; i < Option.Count(); i++)
{
if (Option[i][0] == 53)
{
if (Option[i][2] == 1)
{
DHCPType = "DHCP Discover";
}
if (Option[i][2] == 2)
{
DHCPType = "DHCP Offer";
}
if (Option[i][2] == 3)
{
DHCPType = "DHCP Request";
}
if (Option[i][2] == 4)
{
DHCPType = "DHCP Decline";
}
if (Option[i][2] == 5)
{
DHCPType = "DHCP ACK";
}
if (Option[i][2] == 6)
{
DHCPType = "DHCP NACK";
}
if (Option[i][2] == 7)
{
DHCPType = "DHCP Release";
}
if (Option[i][2] == 8)
{
DHCPType = "DHCP Inform";
}
}
}
// Display dhcp messeage
//rtbMess.Text += packet.ToText() + "\r\n"; // d.ToText() la ham tra ve mot string tu DHCPPacket
ListViewItem type = new ListViewItem(DHCPType);
lv_Message.Items.Add(type);
ListViewItem.ListViewSubItem time = new ListViewItem.ListViewSubItem(type, DateTime.Now.ToString());
type.SubItems.Add(time);
}
private void btnExtendIP_Click(object sender, EventArgs e) // Extend button
{
if (haveip)
{
Send_DHCPRequest(offer_saved, DHCPServer_IP, 2);
}
else
{
FileStream fs;
try
{
fs = new FileStream("IP", FileMode.Open);
byte[] load = new byte[376];
fs.Read(load, 0, 376);
fs.Close();
offer_saved.BytesToDHCPPacket(load);
List <byte[]> Option = offer_saved.optionsplit();
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];
}
break;
}
}
Send_DHCPRequest(offer_saved, DHCPServer_IP, 3);
}
catch (Exception z)
{
MessageBox.Show(z.Message);
return;
}
}
}
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;
}
}
}
void HandlePacket(DHCPPacket packet)
{
// Phan biet cac goi tin request co phai selecting hay khong
bool flag1 = false;
// Xu li goi tin dhcp
List <byte[]> Option = packet.optionsplit();
for (int i = 0; i < Option.Count(); i++) // dhcp server identify khi goi request_new hoac release
{
if (Option[i][0] == 54)
{
if (!network_config.dhcpserver.Equals(new IPAddress(new byte[] { Option[i][2], Option[i][3], Option[i][4], Option[i][5] })))
{
return;
}
flag1 = true; // Neu la goi tin request thi se o trang thai selecting
break;
}
}
for (int i = 0; i < Option.Count(); i++)
{
if (Option[i][0] == 53)
{
if (Option[i][2] == 1) // xac dinh dhcp discover
{
xid.Add(ByteArrayToString(packet.xid));
byte[] b_MacAddress = new byte[packet.hlen];
for (int j = 0; j < packet.hlen; j++)
{
b_MacAddress[j] = packet.chaddr[j];
}
string s_MacAddress = ByteArrayToString(b_MacAddress);
for (int z = 0; z < table.Count(); z++)
{
if (s_MacAddress == table[z].macaddress)
{
Send_DHCPOffer(packet, IPAddress.Parse(table[z].ip));
return;
}
}
IPAddress IP = allocate();
if (IP.Equals(IPAddress.Parse("0.0.0.0"))) // if out of IP
{
return;
}
Send_DHCPOffer(packet, IP);
}
else if (Option[i][2] == 3) // Xac dinh dhcp request
{
byte[] p = new byte[6];
if (!xid.Contains(ByteArrayToString(packet.xid))) // neu xid khong thuoc cac xid dang giap tiep
{
return;
}
IPAddress IP;
IP = new IPAddress(packet.ciaddr); // request o dang rebound, ip -> ciaddr
if (packet.ciaddr.SequenceEqual(new byte[] { 0, 0, 0, 0 })) // chua co ip -> dhcp dang o dang new
{
for (int j = 0; j < Option.Count(); j++)
{
if (Option[j][0] == 50) // request IP address
{
IP = new IPAddress(new byte[] { Option[j][2], Option[j][3], Option[j][4], Option[j][5] });
break;
}
}
}
byte[] b_MacAddress = new byte[packet.hlen];
for (int j = 0; j < packet.hlen; j++)
{
b_MacAddress[j] = packet.chaddr[j];
}
string s_MacAddress = ByteArrayToString(b_MacAddress);
Item item = new Item();
item.macaddress = s_MacAddress;
item.ip = IP.ToString();
Int64 epoch = (int)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds; // setup item
item.time = epoch + network_config.leasetime;
bool flag2 = false;
for (int j = 0; j < table.Count(); j++)
{
if (table[j].ip == item.ip)
{
if (table[j].macaddress == item.macaddress) // goi tin dang xin gia han
{
table.RemoveAt(j); // xoa goi cu
flag2 = true;
}
else
{
Send_DHCPNak(packet);
return;
}
}
}
if (flag1 || flag2) // La goi tin dhcp request seleting thi xac nhan, neu la cac goi tin renew, reboot thi phai co san IP trong bang
{
table.Add(item); // add goi moi vo
Send_DHCPAck(packet, IP); // send goi ack
}
}
else // goi dhcp release
{
IPAddress IP = new IPAddress(packet.ciaddr);
byte[] b_MacAddress = new byte[packet.hlen];
for (int j = 0; j < packet.hlen; j++)
{
b_MacAddress[j] = packet.chaddr[j];
}
string s_mac_address = ByteArrayToString(b_MacAddress);
for (int j = 0; j < table.Count(); j++) // Duyet ban va xoa di ip
{
if (table[j].ip == IP.ToString() || table[j].macaddress == s_mac_address)
{
table.RemoveAt(j);
j--;
}
}
}
break;
}
}
}
