Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * IPv6 library code, needed by static components when full IPv6 support is | |
3 | * not configured or static. | |
4 | */ | |
bc3b2d7f | 5 | #include <linux/export.h> |
1da177e4 LT |
6 | #include <net/ipv6.h> |
7 | ||
1ab1457c | 8 | /* |
1da177e4 LT |
9 | * find out if nexthdr is a well-known extension header or a protocol |
10 | */ | |
11 | ||
a50feda5 | 12 | bool ipv6_ext_hdr(u8 nexthdr) |
1da177e4 | 13 | { |
1ab1457c | 14 | /* |
1da177e4 LT |
15 | * find out if nexthdr is an extension header or a protocol |
16 | */ | |
a02cec21 | 17 | return (nexthdr == NEXTHDR_HOP) || |
1da177e4 LT |
18 | (nexthdr == NEXTHDR_ROUTING) || |
19 | (nexthdr == NEXTHDR_FRAGMENT) || | |
20 | (nexthdr == NEXTHDR_AUTH) || | |
21 | (nexthdr == NEXTHDR_NONE) || | |
a02cec21 | 22 | (nexthdr == NEXTHDR_DEST); |
1da177e4 | 23 | } |
81bd60b5 | 24 | EXPORT_SYMBOL(ipv6_ext_hdr); |
1da177e4 LT |
25 | |
26 | /* | |
27 | * Skip any extension headers. This is used by the ICMP module. | |
28 | * | |
29 | * Note that strictly speaking this conflicts with RFC 2460 4.0: | |
1ab1457c | 30 | * ...The contents and semantics of each extension header determine whether |
1da177e4 LT |
31 | * or not to proceed to the next header. Therefore, extension headers must |
32 | * be processed strictly in the order they appear in the packet; a | |
33 | * receiver must not, for example, scan through a packet looking for a | |
34 | * particular kind of extension header and process that header prior to | |
35 | * processing all preceding ones. | |
1ab1457c | 36 | * |
1da177e4 | 37 | * We do exactly this. This is a protocol bug. We can't decide after a |
1ab1457c | 38 | * seeing an unknown discard-with-error flavour TLV option if it's a |
1da177e4 LT |
39 | * ICMP error message or not (errors should never be send in reply to |
40 | * ICMP error messages). | |
1ab1457c | 41 | * |
1da177e4 LT |
42 | * But I see no other way to do this. This might need to be reexamined |
43 | * when Linux implements ESP (and maybe AUTH) headers. | |
44 | * --AK | |
45 | * | |
0d3d077c HX |
46 | * This function parses (probably truncated) exthdr set "hdr". |
47 | * "nexthdrp" initially points to some place, | |
1da177e4 LT |
48 | * where type of the first header can be found. |
49 | * | |
50 | * It skips all well-known exthdrs, and returns pointer to the start | |
51 | * of unparsable area i.e. the first header with unknown type. | |
52 | * If it is not NULL *nexthdr is updated by type/protocol of this header. | |
53 | * | |
54 | * NOTES: - if packet terminated with NEXTHDR_NONE it returns NULL. | |
55 | * - it may return pointer pointing beyond end of packet, | |
56 | * if the last recognized header is truncated in the middle. | |
57 | * - if packet is truncated, so that all parsed headers are skipped, | |
58 | * it returns NULL. | |
59 | * - First fragment header is skipped, not-first ones | |
60 | * are considered as unparsable. | |
75f2811c JG |
61 | * - Reports the offset field of the final fragment header so it is |
62 | * possible to tell whether this is a first fragment, later fragment, | |
63 | * or not fragmented. | |
1da177e4 LT |
64 | * - ESP is unparsable for now and considered like |
65 | * normal payload protocol. | |
66 | * - Note also special handling of AUTH header. Thanks to IPsec wizards. | |
67 | * | |
68 | * --ANK (980726) | |
69 | */ | |
70 | ||
75f2811c JG |
71 | int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp, |
72 | __be16 *frag_offp) | |
1da177e4 LT |
73 | { |
74 | u8 nexthdr = *nexthdrp; | |
75 | ||
75f2811c JG |
76 | *frag_offp = 0; |
77 | ||
1da177e4 LT |
78 | while (ipv6_ext_hdr(nexthdr)) { |
79 | struct ipv6_opt_hdr _hdr, *hp; | |
80 | int hdrlen; | |
81 | ||
1da177e4 LT |
82 | if (nexthdr == NEXTHDR_NONE) |
83 | return -1; | |
84 | hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr); | |
85 | if (hp == NULL) | |
0d3d077c | 86 | return -1; |
1da177e4 | 87 | if (nexthdr == NEXTHDR_FRAGMENT) { |
e69a4adc | 88 | __be16 _frag_off, *fp; |
1da177e4 LT |
89 | fp = skb_header_pointer(skb, |
90 | start+offsetof(struct frag_hdr, | |
91 | frag_off), | |
92 | sizeof(_frag_off), | |
93 | &_frag_off); | |
94 | if (fp == NULL) | |
95 | return -1; | |
96 | ||
75f2811c JG |
97 | *frag_offp = *fp; |
98 | if (ntohs(*frag_offp) & ~0x7) | |
1da177e4 LT |
99 | break; |
100 | hdrlen = 8; | |
101 | } else if (nexthdr == NEXTHDR_AUTH) | |
1ab1457c | 102 | hdrlen = (hp->hdrlen+2)<<2; |
1da177e4 | 103 | else |
1ab1457c | 104 | hdrlen = ipv6_optlen(hp); |
1da177e4 LT |
105 | |
106 | nexthdr = hp->nexthdr; | |
1da177e4 LT |
107 | start += hdrlen; |
108 | } | |
109 | ||
110 | *nexthdrp = nexthdr; | |
111 | return start; | |
112 | } | |
1da177e4 | 113 | EXPORT_SYMBOL(ipv6_skip_exthdr); |