public static IPFrame ToIPFrame(IcmpFrame frame)
{
if (frame == null)
{
throw new ArgumentNullException(nameof(frame));
}
if (frame.AddressFamily != AddressFamily.InterNetwork)
{
throw new ArgumentNullException("ICMP frames of this address family type are not supported.");
}
BufferSegment payload = frame.Payload;
byte[] buffer = new byte[sizeof(icmp_hdr) + payload?.Length ?? 0];
fixed(byte *pinned = buffer)
{
icmp_hdr *icmp = (icmp_hdr *)pinned;
icmp->icmp_type = (byte)frame.Type;
icmp->icmp_code = frame.Code;
icmp->icmp_id = CheckSum.ntohs(frame.Identification);
icmp->icmp_seq = CheckSum.ntohs(frame.Sequence);
icmp->icmp_chksum = 0;
if (payload != null)
{
Marshal.Copy(payload.Buffer, payload.Offset, (IntPtr)(pinned + sizeof(icmp_hdr)), payload.Length);
}
icmp->icmp_chksum = CheckSum.inet_chksum(icmp, buffer.Length);
if (icmp->icmp_chksum == 0)
{
icmp->icmp_chksum = 0xffff;
}
}
return(new IPFrame(ProtocolType.Icmp, frame.Source, frame.Destination, new BufferSegment(buffer))
{
Ttl = frame.Ttl,
SourceMacAddress = frame.SourceMacAddress,
DestinationMacAddress = frame.DestinationMacAddress
});
}
public static IcmpFrame ParseFrame(IPFrame ip, bool checksum = true)
{
if (ip == null)
{
return(null);
}
IcmpFrame frame = null;
BufferSegment segment = ip.Payload;
segment.UnsafeAddrOfPinnedArrayElement(p =>
{
icmp_hdr *icmp = (icmp_hdr *)p;
if (checksum && icmp->icmp_chksum != 0)
{
ushort cksum = CheckSum.inet_chksum(icmp, segment.Length);
if (cksum != 0)
{
return;
}
}
int payload_size = segment.Length - sizeof(icmp_hdr);
if (payload_size < 0)
{
return;
}
frame = new IcmpFrame(ip.Source, ip.Destination, new BufferSegment(segment.Buffer, segment.Offset + sizeof(icmp_hdr), payload_size))
{
Type = (IcmpType)icmp->icmp_type,
Code = icmp->icmp_code,
Identification = CheckSum.ntohs(icmp->icmp_id),
Sequence = CheckSum.ntohs(icmp->icmp_seq),
Ttl = ip.Ttl,
SourceMacAddress = ip.SourceMacAddress,
DestinationMacAddress = ip.DestinationMacAddress,
};
});
return(frame);
}
