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