public static UdpFrame ParseFrame(IPFrame ip, bool checksum = true)
{
if (ip == null)
{
return(null);
}
UdpFrame frame = null;
BufferSegment payload = ip.Payload;
payload.UnsafeAddrOfPinnedArrayElement((p) =>
{
udp_hdr *udphdr = (udp_hdr *)p;
if (udphdr == null)
{
return;
}
if (payload.Length != CheckSum.ntohs(udphdr->len)) // 错误的数据报
{
return;
}
int offset = sizeof(udp_hdr);
int len = payload.Length - offset;
if (len <= 0)
{
return;
}
if (checksum && udphdr->chksum != 0)
{
uint pseudo_checksum = CheckSum.inet_chksum_pseudo((byte *)p.ToPointer(),
(uint)ProtocolType.Udp,
(uint)payload.Length,
ip.SourceAddressV4,
ip.DestinationAddressV4);
if (pseudo_checksum != 0)
{
return;
}
}
BufferSegment message = new BufferSegment(payload.Buffer, payload.Offset + offset, len);
frame = new UdpFrame(
new IPEndPoint(ip.Source, CheckSum.ntohs(udphdr->src)),
new IPEndPoint(ip.Destination, CheckSum.ntohs(udphdr->dest)), message)
{
Ttl = ip.Ttl,
SourceMacAddress = ip.SourceMacAddress,
DestinationMacAddress = ip.DestinationMacAddress
};
});
return(frame);
}
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);
}
public static IPFrame ParseFrame(BufferSegment packet, bool checksum = true)
{
if (packet == null)
{
return(null);
}
IPFrame frame = null;
packet.UnsafeAddrOfPinnedArrayElement((payload) =>
{
ip_hdr *iphdr = (ip_hdr *)payload;
if (iphdr == null)
{
return;
}
if (ip_hdr.IPH_V(iphdr) != 4)
{
return;
}
int iphdr_hlen = ip_hdr.IPH_HL(iphdr) << 2;
if (iphdr_hlen > packet.Length)
{
return;
}
if (iphdr_hlen < IP_HLEN)
{
return;
}
int ttl = ip_hdr.IPH_TTL(iphdr);
if (ttl <= 0)
{
return;
}
if (checksum && iphdr->_chksum != 0)
{
int cksum = CheckSum.inet_chksum(iphdr, iphdr_hlen);
if (cksum != 0)
{
return;
}
}
if (ip_addr_isbroadcast(iphdr->src) || ip_addr_isbroadcast(iphdr->dest))
{
return;
}
if ((ip_hdr.IPH_OFFSET(iphdr) & CheckSum.ntohs((ushort)(IPFlags.IP_OFFMASK | IPFlags.IP_MF))) != 0) // 不允许IP分片(NAT不太容易处理好分片)
{
return;
}
ProtocolType protocolType = (ProtocolType)ip_hdr.IPH_PROTO(iphdr);
if (protocolType == (ProtocolType)IP_PROTO_UDP ||
protocolType == (ProtocolType)IP_PROTO_TCP ||
protocolType == (ProtocolType)IP_PROTO_ICMP ||
protocolType == (ProtocolType)IP_PROTO_GRE)
{
BufferSegment message_data = new BufferSegment(packet.Buffer,
packet.Offset + iphdr_hlen,
packet.Length - iphdr_hlen);
BufferSegment options_data = null;
int options_size = (iphdr_hlen - sizeof(ip_hdr));
if (options_size <= 0)
{
options_data = new BufferSegment(BufferSegment.Empty);
}
else
{
options_data = new BufferSegment(packet.Buffer,
packet.Offset + sizeof(ip_hdr), options_size);
}
frame = new IPFrame(protocolType,
new IPAddress(iphdr->src),
new IPAddress(iphdr->dest),
message_data)
{
Id = CheckSum.ntohs(iphdr->_id),
Ttl = ttl,
Tos = iphdr->_tos,
Options = options_data,
Flags = (IPFlags)CheckSum.ntohs(iphdr->_flags),
};
}
});
return(frame);
}
public static TcpFrame ParseFrame(IPFrame ip, bool checksum = true)
{
if (ip == null)
{
return(null);
}
TcpFrame frame = null;
BufferSegment packet = ip.Payload;
packet.UnsafeAddrOfPinnedArrayElement((p) =>
{
tcp_hdr *tcphdr = (tcp_hdr *)p;
if (tcphdr == null)
{
return;
}
int hdrlen_bytes = TCPH_HDRLEN_BYTES(tcphdr);
if (hdrlen_bytes < TCP_HLEN || hdrlen_bytes > packet.Length) // 错误的数据报
{
return;
}
int len = packet.Length - hdrlen_bytes;
if (len < 0)
{
return;
}
TcpFlags flags = (TcpFlags)TCPH_FLAGS(tcphdr);
if (checksum && tcphdr->chksum != 0)
{
uint pseudo_checksum = CheckSum.inet_chksum_pseudo((byte *)p.ToPointer(),
(uint)ProtocolType.Tcp,
(uint)packet.Length,
ip.SourceAddressV4,
ip.DestinationAddressV4);
if (pseudo_checksum != 0)
{
return;
}
}
long payload_offset = 0;
fixed(byte *stream = packet.Buffer)
{
payload_offset = ((byte *)p + hdrlen_bytes) - stream;
}
BufferSegment message_data = new BufferSegment(packet.Buffer, unchecked ((int)payload_offset), len);
BufferSegment options_data = null;
int options_size = hdrlen_bytes - sizeof(tcp_hdr);
if (options_size <= 0)
{
options_data = new BufferSegment(BufferSegment.Empty);
}
else
{
options_data = new BufferSegment(packet.Buffer,
packet.Offset + sizeof(tcp_hdr), options_size);
}
frame = new TcpFrame(new IPEndPoint(ip.Source, CheckSum.ntohs(tcphdr->src)), new IPEndPoint(ip.Destination, CheckSum.ntohs(tcphdr->dest)), message_data)
{
Ttl = ip.Ttl,
AcknowledgeNo = CheckSum.ntohl(tcphdr->ackno),
SequenceNo = CheckSum.ntohl(tcphdr->seqno),
WindowSize = CheckSum.ntohs(tcphdr->wnd),
Flags = flags,
SourceMacAddress = ip.SourceMacAddress,
DestinationMacAddress = ip.DestinationMacAddress,
Options = options_data,
UrgentPointer = CheckSum.ntohs(tcphdr->urgp)
};
});
return(frame);
}
