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
42
43
44
45
46
47
48
|
#include <stdio.h>
#include "libpacketdump.h"
#define LE(lhs,n) \
do { \
uint64_t num=0; \
int size=0; \
if ((offset+n)>len*8) return; \
if (n>16) { \
num=htonl(*(uint32_t*)(packet+offset/8));\
size = 32;\
} else if (n>8) { \
num=htons(*(uint16_t*)(packet+offset/8));\
size = 16; \
} else { \
num=*(uint8_t*)(packet+offset/8); \
size = 8; \
} \
num=num>>(size - (n + (offset % 8))); \
offset+=n; \
lhs=num&((1<<(n))-1); \
} while(0)
DLLEXPORT void decode(int link_type UNUSED,const char *packet,unsigned len)
{
unsigned int offset=0;
int value;
int more = 0;
LE(value,20); printf(" MPLS: Label: %d\n",value);
LE(value,3); printf(" MPLS: Class of service: %d\n",value);
LE(value,1); printf(" MPLS: Stack: %s\n",value?"Last" :"More");
if (value == 0) more = 1;
LE(value,8); printf(" MPLS: TTL: %d\n",value);
/* MPLS doesn't say what it's encapsulating, so we make an educated
* guess and pray.
*/
if (more)
decode_next(packet+offset/8,len-4,"eth",0x8847);
else if ((*(packet+4)&0xF0) == 0x40)
decode_next(packet+offset/8,len-4,"eth",0x0800);
else if ((*(packet+4)&0xF0) == 0x60)
decode_next(packet+offset/8,len-4,"eth",0x86DD);
else
decode_next(packet+offset/8,len-4,"link",1);
return;
}
|
