net/ipv6/udp_offload.c

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

File Facts

System
Linux kernel
Corpus path
net/ipv6/udp_offload.c
Extension
.c
Size
5634 bytes
Lines
207
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: implementation source
Status
source 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 (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
			if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
				goto out;
		}

		/* Find the unfragmentable header and shift it left by frag_hdr_sz
		 * bytes to insert fragment header.
		 */
		err = ip6_find_1stfragopt(skb, &prevhdr);
		if (err < 0)
			return ERR_PTR(err);
		unfrag_ip6hlen = err;
		nexthdr = *prevhdr;
		*prevhdr = NEXTHDR_FRAGMENT;
		unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
			     unfrag_ip6hlen + tnl_hlen;
		packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
		memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);

		SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
		skb->mac_header -= frag_hdr_sz;
		skb->network_header -= frag_hdr_sz;

		fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
		fptr->nexthdr = nexthdr;
		fptr->reserved = 0;
		fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb);

		/* Fragment the skb. ipv6 header and the remaining fields of the
		 * fragment header are updated in ipv6_gso_segment()
		 */
		segs = skb_segment(skb, features);
	}

out:
	return segs;
}

static struct sock *udp6_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
					__be16 dport)
{
	const struct ipv6hdr *iph = skb_gro_network_header(skb);
	struct net *net = dev_net_rcu(skb->dev);
	struct sock *sk;
	int iif, sdif;

	sk = udp_tunnel_sk(net, true);
	if (sk && dport == htons(sk->sk_num))
		return sk;

	inet6_get_iif_sdif(skb, &iif, &sdif);

	return __udp6_lib_lookup(net, &iph->saddr, sport,
				 &iph->daddr, dport, iif, sdif, NULL);
}

struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)
{
	struct udphdr *uh = udp_gro_udphdr(skb);
	struct sock *sk = NULL;
	struct sk_buff *pp;

	if (unlikely(!uh))
		goto flush;

	/* Don't bother verifying checksum if we're going to flush anyway. */
	if (NAPI_GRO_CB(skb)->flush)
		goto skip;

	if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
						 ip6_gro_compute_pseudo))
		goto flush;
	else if (uh->check)
		skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
					     ip6_gro_compute_pseudo);

skip:
	if (static_branch_unlikely(&udpv6_encap_needed_key))
		sk = udp6_gro_lookup_skb(skb, uh->source, uh->dest);

	pp = udp_gro_receive(head, skb, uh, sk);
	return pp;

flush:
	NAPI_GRO_CB(skb)->flush = 1;
	return NULL;
}

int udp6_gro_complete(struct sk_buff *skb, int nhoff)
{

Annotation

Implementation Notes