/* * IPv6 library code, needed by static components when full IPv6 support is * not configured or static. */ #include <linux/export.h> #include <net/ipv6.h> /* * find out if nexthdr is a well-known extension header or a protocol */ int ipv6_ext_hdr(u8 nexthdr) { /* * find out if nexthdr is an extension header or a protocol */ return (nexthdr == NEXTHDR_HOP) || (nexthdr == NEXTHDR_ROUTING) || (nexthdr == NEXTHDR_FRAGMENT) || (nexthdr == NEXTHDR_AUTH) || (nexthdr == NEXTHDR_NONE) || (nexthdr == NEXTHDR_DEST); } /* * Skip any extension headers. This is used by the ICMP module. * * Note that strictly speaking this conflicts with RFC 2460 4.0: * ...The contents and semantics of each extension header determine whether * or not to proceed to the next header. Therefore, extension headers must * be processed strictly in the order they appear in the packet; a * receiver must not, for example, scan through a packet looking for a * particular kind of extension header and process that header prior to * processing all preceding ones. * * We do exactly this. This is a protocol bug. We can't decide after a * seeing an unknown discard-with-error flavour TLV option if it's a * ICMP error message or not (errors should never be send in reply to * ICMP error messages). * * But I see no other way to do this. This might need to be reexamined * when Linux implements ESP (and maybe AUTH) headers. * --AK * * This function parses (probably truncated) exthdr set "hdr". * "nexthdrp" initially points to some place, * where type of the first header can be found. * * It skips all well-known exthdrs, and returns pointer to the start * of unparsable area i.e. the first header with unknown type. * If it is not NULL *nexthdr is updated by type/protocol of this header. * * NOTES: - if packet terminated with NEXTHDR_NONE it returns NULL. * - it may return pointer pointing beyond end of packet, * if the last recognized header is truncated in the middle. * - if packet is truncated, so that all parsed headers are skipped, * it returns NULL. * - First fragment header is skipped, not-first ones * are considered as unparsable. * - ESP is unparsable for now and considered like * normal payload protocol. * - Note also special handling of AUTH header. Thanks to IPsec wizards. * * --ANK (980726) */ int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp) { u8 nexthdr = *nexthdrp; while (ipv6_ext_hdr(nexthdr)) { struct ipv6_opt_hdr _hdr, *hp; int hdrlen; if (nexthdr == NEXTHDR_NONE) return -1; hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr); if (hp == NULL) return -1; if (nexthdr == NEXTHDR_FRAGMENT) { __be16 _frag_off, *fp; fp = skb_header_pointer(skb, start+offsetof(struct frag_hdr, frag_off), sizeof(_frag_off), &_frag_off); if (fp == NULL) return -1; if (ntohs(*fp) & ~0x7) break; hdrlen = 8; } else if (nexthdr == NEXTHDR_AUTH) hdrlen = (hp->hdrlen+2)<<2; else hdrlen = ipv6_optlen(hp); nexthdr = hp->nexthdr; start += hdrlen; } *nexthdrp = nexthdr; return start; } EXPORT_SYMBOL(ipv6_ext_hdr); EXPORT_SYMBOL(ipv6_skip_exthdr);