public static IDhcpOption !Parse(byte option,
byte length,
byte[] !srcBuffer,
int offset)
{
if (length != payloadLength)
{
throw new InvalidDhcpOptionLength();
}
return(new DhcpIPv4Option(option,
IPv4.ParseBytes(srcBuffer, offset)));
}
public static IDhcpOption !Parse(byte option, byte length,
byte[] !srcBuffer, int offset)
{
if ((length & 3) != 0)
{
throw new InvalidDhcpOptionLength();
}
IPv4 [] addresses = new IPv4 [length / 4];
for (int i = 0; i < addresses.Length; i++)
{
addresses[i] = IPv4.ParseBytes(srcBuffer, offset);
offset += IPv4.Length;
}
return(new DhcpMultiIPv4Option(option, addresses));
}
// creates an arp reply using the received packet
// the packet must be an arp request
// the responder should pass its own IP and MAC address
// we assume that we have the same hw type
// (return offset_arp size)
public static int CreateArpReply(ref byte[] !pkt,
IPv4 selfIP,
EthernetAddress selfMACAddr)
{
int offset = 14; // arp message starts here.
int o = offset;
// check we have enough packet
if (pkt.Length - offset < Size)
{
return(offset);
}
// check hardware type == 0x0001 (Ethernet)
if (pkt[o++] != 0x00 || pkt[o++] != 0x01)
{
return(offset);
}
// check protocol type == 0x0800 (IP)
if (pkt[o++] != 0x08 || pkt[o++] != 0x00)
{
return(offset); // error
}
// check addresses len
if (pkt[o++] != 0x06)
{
return(offset);
}
if (pkt[o++] != 0x04)
{
return(offset);
}
// operation code
Type opcode = (Type)(((int)pkt[o++] << 8) | (int)pkt[o++]);
// we need a request message.
if (opcode != Type.ARP_REQUEST)
{
return(offset);
}
// sender HW & IP
EthernetAddress senderhw = EthernetAddress.ParseBytes(pkt, o);
o += EthernetAddress.Length;
IPv4 senderIP = IPv4.ParseBytes(pkt, o);
o += IPv4.Length;
// target HW & IP
// EthernetAddress targethw = EthernetAddress.ParseBytes(pkt, o);
o += EthernetAddress.Length;
// IPv4 targetIP = IPv4.ParseBytes(pkt, o);
o += IPv4.Length;
// all is well, do our stuff...
// 1. set local hw address to arp's source ether address + fix dest addresses
// 2. set arp type = ARP_REPLY
// 3. set the destination's ethernet address to self
// and target is the source of the request.
o = offset + 6; // opcode entry
pkt[o++] = (byte)(((ushort)Type.ARP_REPLY) >> 8);
pkt[o++] = (byte)Type.ARP_REPLY;
// set hw and IP address
selfMACAddr.CopyOut(pkt, o);
o += EthernetAddress.Length;
selfIP.CopyOut(pkt, o);
o += IPv4.Length;
// setup dest address to the requesting host address
senderhw.CopyOut(pkt, o);
o += EthernetAddress.Length;
senderIP.CopyOut(pkt, o);
o += IPv4.Length;
// set ethernet level addresses
Array.Copy(pkt, 6, pkt, 0, 6); // src -> dest
selfMACAddr.CopyOut(pkt, 6); // self -> src
return(offset + Size);
}
/// <summary>
/// Gets the DNS information for the specified DNS host name.
/// </summary>
public StatusCode GetHostByName(string name,
out IPv4HostEntry hostEntry)
{
hostEntry = null;
IPv4 dnsServer = DnsServer;
if (dnsServer == IPv4.Zero)
{
return(StatusCode.NoNameServer);
}
Dns.Query q = new Dns.Query(name, Dns.Type.A, Dns.Class.Internet);
Dns.Format answer;
StatusCode askResponse = Ask(dnsServer, q, out answer);
if (askResponse != StatusCode.Success)
{
return(askResponse);
}
assert answer != null;
if (answer.GetRCode() != Dns.RCode.NoError)
{
DebugPrint("Dns query failed: RCode = {0}\n", answer.GetRCode());
return(StatusCode.RequestFailed);
}
hostEntry = new IPv4HostEntry(new string [] { name }, new IPv4[] {});
ArrayList addressList = new ArrayList();
foreach (Dns.ResourceRecord !rr in answer.AnswerRRs)
{
if (rr.Type != Dns.Type.A || rr.Class != Dns.Class.Internet)
{
continue;
}
byte [] rdata = rr.RData;
if (rdata == null)
{
continue;
}
if ((rdata.Length % IPv4.Length) != 0)
{
continue;
}
int offset = 0;
while (offset != rdata.Length)
{
addressList.Add(IPv4.ParseBytes(rdata, offset));
offset += 4;
}
}
IPv4[] al = hostEntry.AddressList = new IPv4 [addressList.Count];
for (int i = 0; i < addressList.Count; i++)
{
al[i] = (IPv4)(!)addressList[i];
}
return(StatusCode.Success);
}