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
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
|
#include <linux/ipv6.h>
#include <linux/version.h>
#include <net/ipv6.h>
#ifndef HAVE_IP6_FH_F_SKIP_RH
/*
* find the offset to specified header or the protocol number of last header
* if target < 0. "last header" is transport protocol header, ESP, or
* "No next header".
*
* Note that *offset is used as input/output parameter. an if it is not zero,
* then it must be a valid offset to an inner IPv6 header. This can be used
* to explore inner IPv6 header, eg. ICMPv6 error messages.
*
* If target header is found, its offset is set in *offset and return protocol
* number. Otherwise, return -1.
*
* If the first fragment doesn't contain the final protocol header or
* NEXTHDR_NONE it is considered invalid.
*
* Note that non-1st fragment is special case that "the protocol number
* of last header" is "next header" field in Fragment header. In this case,
* *offset is meaningless and fragment offset is stored in *fragoff if fragoff
* isn't NULL.
*
* if flags is not NULL and it's a fragment, then the frag flag
* IP6_FH_F_FRAG will be set. If it's an AH header, the
* IP6_FH_F_AUTH flag is set and target < 0, then this function will
* stop at the AH header. If IP6_FH_F_SKIP_RH flag was passed, then this
* function will skip all those routing headers, where segements_left was 0.
*/
int rpl_ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
int target, unsigned short *fragoff, int *flags)
{
unsigned int start = skb_network_offset(skb) + sizeof(struct ipv6hdr);
u8 nexthdr = ipv6_hdr(skb)->nexthdr;
unsigned int len;
bool found;
if (fragoff)
*fragoff = 0;
if (*offset) {
struct ipv6hdr _ip6, *ip6;
ip6 = skb_header_pointer(skb, *offset, sizeof(_ip6), &_ip6);
if (!ip6 || (ip6->version != 6)) {
printk(KERN_ERR "IPv6 header not found\n");
return -EBADMSG;
}
start = *offset + sizeof(struct ipv6hdr);
nexthdr = ip6->nexthdr;
}
len = skb->len - start;
do {
struct ipv6_opt_hdr _hdr, *hp;
unsigned int hdrlen;
found = (nexthdr == target);
if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE) {
if (target < 0 || found)
break;
return -ENOENT;
}
hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
if (hp == NULL)
return -EBADMSG;
if (nexthdr == NEXTHDR_ROUTING) {
struct ipv6_rt_hdr _rh, *rh;
rh = skb_header_pointer(skb, start, sizeof(_rh),
&_rh);
if (rh == NULL)
return -EBADMSG;
if (flags && (*flags & IP6_FH_F_SKIP_RH) &&
rh->segments_left == 0)
found = false;
}
if (nexthdr == NEXTHDR_FRAGMENT) {
unsigned short _frag_off;
__be16 *fp;
if (flags) /* Indicate that this is a fragment */
*flags |= IP6_FH_F_FRAG;
fp = skb_header_pointer(skb,
start+offsetof(struct frag_hdr,
frag_off),
sizeof(_frag_off),
&_frag_off);
if (fp == NULL)
return -EBADMSG;
_frag_off = ntohs(*fp) & ~0x7;
if (_frag_off) {
if (target < 0 &&
((!ipv6_ext_hdr(hp->nexthdr)) ||
hp->nexthdr == NEXTHDR_NONE)) {
if (fragoff)
*fragoff = _frag_off;
return hp->nexthdr;
}
return -ENOENT;
}
hdrlen = 8;
} else if (nexthdr == NEXTHDR_AUTH) {
if (flags && (*flags & IP6_FH_F_AUTH) && (target < 0))
break;
hdrlen = (hp->hdrlen + 2) << 2;
} else
hdrlen = ipv6_optlen(hp);
if (!found) {
nexthdr = hp->nexthdr;
len -= hdrlen;
start += hdrlen;
}
} while (!found);
*offset = start;
return nexthdr;
}
EXPORT_SYMBOL_GPL(rpl_ipv6_find_hdr);
#endif
|
