1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
|
(* Parse and display an IPv4 header from a file.
* $Id: ipv4_header.ml 142 2008-07-17 15:45:56Z richard.wm.jones $
*)
open Printf
let header = Bitstring.bitstring_of_file "ipv4_header.dat"
let () =
bitmatch header with
| { version : 4; hdrlen : 4; tos : 8; length : 16;
identification : 16; flags : 3; fragoffset : 13;
ttl : 8; protocol : 8; checksum : 16;
source : 32;
dest : 32;
options : (hdrlen-5)*32 : bitstring;
payload : -1 : bitstring }
when version = 4 ->
printf "IPv%d:\n" version;
printf " header length: %d * 32 bit words\n" hdrlen;
printf " type of service: %d\n" tos;
printf " packet length: %d bytes\n" length;
printf " identification: %d\n" identification;
printf " flags: %d\n" flags;
printf " fragment offset: %d\n" fragoffset;
printf " ttl: %d\n" ttl;
printf " protocol: %d\n" protocol;
printf " checksum: %d\n" checksum;
printf " source: %lx dest: %lx\n" source dest;
printf " header options + padding:\n";
Bitstring.hexdump_bitstring stdout options;
printf " packet payload:\n";
Bitstring.hexdump_bitstring stdout payload
| { version : 4 } ->
eprintf "cannot parse IP version %d\n" version
| { _ } as header ->
eprintf "data is smaller than one nibble:\n";
Bitstring.hexdump_bitstring stderr header
|
