[Jnetstream-users] Error in TCP decode

[Frédéric D. <fre...@dr...>]

Hi,

I  have some trouble decoding IP and TCP headers. the header length and 
the offset are wrongly decoded in most of the packets.

Did I do something wrong?

Regards,
Frederic Dreier



Console output -------------------------------
PACKET DUMP::
00 12 3F 19 FC 3F 00 07
84 BC A0 C0 08 00 45 00
00 28 9D 7A 40 00 2B 06
25 94 D0 50 98 03 81 AD
A2 C0 00 50 D7 59 29 F4
BC EF 33 C8 F3 C5 50 11
Vers : 4
Hlen : 4 <----- should be 5
TOS  : 0
Lgt  : 40
ident: 40314
flags: 2
offs : 1    <---- should be 0
TTL  : 43
Prot : 6
Src  : 208.80.152.3
Dst  : 129.173.162.192
Console output -------------------------------



Code snipet ------------------------------
                           Ip4 ipHd = packet.getHeader(Ip4.class);
                           Tcp tcpHd = packet.getHeader(Tcp.class);
                           System.out.println("PACKET DUMP::");
                           for (int i = 0; i < 6; i++) {
                               for (int k = i * 8; k < ((i + 1) * 8); 
k++) {
                                   System.out.printf("%02X ", 
packet.getBuffer().getBackingBuffer().get(k) & 0xFF);
                               }
                               System.out.println();
                           }
                           System.out.printf("Vers : %d\n", ipHd.ver());
                           System.out.printf("Hlen : %d\n", ipHd.hlen());
                           System.out.printf("TOS  : %d\n", ipHd.tos());
                           System.out.printf("Lgt  : %d\n", ipHd.length());
                           System.out.printf("ident: %d\n", 
ipHd.id()&0xFFFF);
                           System.out.printf("flags: %d\n", ipHd.flags());
                           System.out.printf("offs : %d\n", ipHd.offset());
                           System.out.printf("TTL  : %d\n", ipHd.ttl());
                           System.out.printf("Prot : %d\n", 
ipHd.protocol());
                           System.out.printf("Src  : %s\n", ipHd.source());
                           System.out.printf("Dst  : %s\n", 
ipHd.destination());
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