net/ipv6/exthdrs_core.c

Source file repositories/reference/linux-study-clean/net/ipv6/exthdrs_core.c

File Facts

System
Linux kernel
Corpus path
net/ipv6/exthdrs_core.c
Extension
.c
Size
7863 bytes
Lines
290
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

Dependency Surface

Detected Declarations

Annotated Snippet

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)
				return -1;

			*frag_offp = *fp;
			if (ntohs(*frag_offp) & ~0x7)
				break;
			hdrlen = 8;
		} else if (nexthdr == NEXTHDR_AUTH)
			hdrlen = ipv6_authlen(hp);
		else
			hdrlen = ipv6_optlen(hp);

		nexthdr = hp->nexthdr;
		start += hdrlen;
	}

	*nexthdrp = nexthdr;
	return start;
}
EXPORT_SYMBOL(ipv6_skip_exthdr);

int ipv6_find_tlv(const struct sk_buff *skb, int offset, int type)
{
	const unsigned char *nh = skb_network_header(skb);
	int packet_len = skb_tail_pointer(skb) - skb_network_header(skb);
	struct ipv6_opt_hdr *hdr;
	int len;

	if (offset + 2 > packet_len)
		goto bad;
	hdr = (struct ipv6_opt_hdr *)(nh + offset);
	len = ((hdr->hdrlen + 1) << 3);

	if (offset + len > packet_len)
		goto bad;

	offset += 2;
	len -= 2;

	while (len > 0) {
		int opttype = nh[offset];
		int optlen;

		if (opttype == type)
			return offset;

		switch (opttype) {
		case IPV6_TLV_PAD1:
			optlen = 1;
			break;
		default:
			if (len < 2)
				goto bad;
			optlen = nh[offset + 1] + 2;
			if (optlen > len)
				goto bad;
			break;
		}
		offset += optlen;
		len -= optlen;
	}
	/* not_found */
 bad:
	return -1;
}
EXPORT_SYMBOL_GPL(ipv6_find_tlv);

/*
 * 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, and 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

Annotation

Implementation Notes