// コンストラクタ
// その他のパケットをベースに作成
public DhcpPacket(DhcpPacket basePacket, DhcpPacket.MessageType message_type, DhcpLeases dhcplease)
: this()
{
if (message_type == MessageType.DHCPOFFER)
{
BuildDHCPOFFER(basePacket, dhcplease);
}
if (message_type == MessageType.DHCPACK)
{
BuildDHCPACK(basePacket, dhcplease);
}
}
// UDP送信
private void SendUDP(IPAddress sourceIPAddress, int sourcePort, IPAddress remoteIPAddress, int remotePort)
{
// 送信元
var localEP = new IPEndPoint(sourceIPAddress, sourcePort);
// 送信先
var remoteEP = new IPEndPoint(remoteIPAddress, remotePort);
// 送信データ
DhcpPacket rcv_packet = new DhcpPacket(this.lastRcvBytes_);
DhcpPacket.MessageType snd_message_type =
(rcv_packet.message_type_ == DhcpPacket.MessageType.DHCPDISCOVER)? DhcpPacket.MessageType.DHCPOFFER:
(rcv_packet.message_type_ == DhcpPacket.MessageType.DHCPREQUEST)? DhcpPacket.MessageType.DHCPACK:
DhcpPacket.MessageType.unknown;
if (snd_message_type == DhcpPacket.MessageType.unknown)
{
return;
}
DhcpPacket snd_packet = new DhcpPacket(rcv_packet, snd_message_type, this.dhcplease_);
byte[] msg = snd_packet.GetPacketBytes();
//データを文字列に変換する
string rcvMsg = "0x" + snd_packet.xid_.ToString("X4") + ", " + snd_packet.message_type_;
//送信したデータの情報をRichTextBoxに表示する
string displayMsg = string.Format("{0} [{1} ({2})] > {3}",
DateTime.Now.ToString("HH:mm:ss.fff"), remoteEP.Address, remoteEP.Port, rcvMsg);
textBoxRcvData.BeginInvoke(
new Action <string>(ShowReceivedString), displayMsg);
// 送信イベントデータ
var ev = new SocketAsyncEventArgs();
ev.RemoteEndPoint = remoteEP;
ev.SetBuffer(msg, 0, msg.Length);
// UDP送信
var socket = new Socket(SocketType.Dgram, ProtocolType.Udp);
socket.Bind(localEP); // bindしたIP、ポートと異なる送信元としたい（場合がある）のでudpClient_は使用しない
socket.SendToAsync(ev); // 非同期で送信
socket.Shutdown(SocketShutdown.Both);
socket.Close();
}
private void BuildDHCPACK(DhcpPacket basePacket, DhcpLeases dhcplease)
{
DhcpLeaseItem item = dhcplease.GetItem(basePacket.chaddr_);
this.op_ = OP.BOOTREPLY;
this.htype_ = basePacket.htype_;
this.hlen_ = basePacket.hlen_;
this.xid_ = basePacket.xid_;
this.ciaddr_ = basePacket.ciaddr_;
this.yiaddr_ = item.yiaddr_;
this.siaddr_ = new IPAddress(0); // 仮
this.giaddr_ = basePacket.giaddr_;
this.chaddr_ = basePacket.chaddr_;
this.options_ = new DhcpOptions(
DhcpPacket.MessageType.DHCPACK,
basePacket.chaddr_,
basePacket.dhcpoption55_,
dhcplease
);
}
// 送信パケットを作成
public byte[] GetPacketBytes()
{
List <byte> list = new List <byte>();
DhcpPacket.addBigEndian(ref list, (byte)(this.op_));
DhcpPacket.addBigEndian(ref list, this.htype_);
DhcpPacket.addBigEndian(ref list, this.hlen_);
DhcpPacket.addBigEndian(ref list, (byte)0); // hops
DhcpPacket.addBigEndian(ref list, this.xid_);
DhcpPacket.addBigEndian(ref list, (UInt16)0); // secs
DhcpPacket.addBigEndian(ref list, (UInt16)0x8000); // flags // 決め打ち
DhcpPacket.addBigEndian(ref list, this.ciaddr_);
DhcpPacket.addBigEndian(ref list, this.yiaddr_);
DhcpPacket.addBigEndian(ref list, this.siaddr_);
DhcpPacket.addBigEndian(ref list, this.giaddr_);
DhcpPacket.addBigEndian(ref list, this.chaddr_);
list.AddRange(new byte[64 + 128]); // sname, file
list.AddRange(this.options_.GetPacketBytes()); // options
return(list.ToArray());
}
//データを受信した時
private void ReceiveCallback(IAsyncResult ar)
{
System.Net.Sockets.UdpClient udp =
(System.Net.Sockets.UdpClient)ar.AsyncState;
//非同期受信を終了する
System.Net.IPEndPoint remoteEP = null;
byte[] rcvBytes;
try
{
rcvBytes = udp.EndReceive(ar, ref remoteEP);
}
catch (System.Net.Sockets.SocketException ex)
{
Console.WriteLine("受信エラー({0}/{1})",
ex.Message, ex.ErrorCode);
return;
}
catch (ObjectDisposedException ex)
{
//すでに閉じている時は終了
Console.WriteLine("Socketは閉じられています。");
return;
}
// 処理対象？
DhcpPacket rcv_packet = new DhcpPacket(rcvBytes);
Boolean reply = this.dhcplease_.AutoReply(rcv_packet.chaddr_);
Boolean match = this.dhcplease_.Matches(rcv_packet.chaddr_);
{
// 受信情報を控えておく（送信データに載せるため）
// 受信データ
lastRcvBytes_ = new byte[rcvBytes.Length];
Array.Copy(rcvBytes, 0, lastRcvBytes_, 0, rcvBytes.Length);
// 受信元
lastRemoteEP_ = remoteEP;
}
//データを文字列に変換する
string rcvMsg = "0x" + rcv_packet.xid_.ToString("X4") + ", " + rcv_packet.message_type_;
//受信したデータと送信者の情報をRichTextBoxに表示する
string displayMsg = string.Format("{0} [{1} ({2})] < {3}",
DateTime.Now.ToString("HH:mm:ss.fff"), remoteEP.Address, remoteEP.Port, rcvMsg);
textBoxRcvData.BeginInvoke(
new Action <string>(ShowReceivedString), displayMsg);
// 応答する
if (match && (!reply))
{
// 当該MACアドレスが登録されていて、
// かつ、「自動応答」が明示的にOFFされている場合は応答しない
}
else
{
// それ以外は応答する
// 送信先のIPアドレスは remoteEP.Address ではなく、ブロードキャスト
SendUDP(sourceIPAddress_, sourcePort_, IPAddress.Broadcast, remoteEP.Port);
}
//再びデータ受信を開始する
udp.BeginReceive(ReceiveCallback, udp);
}
