net/ipv4/tcp_offload.c

Source file repositories/reference/linux-study-clean/net/ipv4/tcp_offload.c

File Facts

System
Linux kernel
Corpus path
net/ipv4/tcp_offload.c
Extension
.c
Size
11750 bytes
Lines
479
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 (before(ts_seq, seq + mss)) {
			skb_shinfo(skb)->tx_flags |= flags;
			skb_shinfo(skb)->tskey = ts_seq;
			return;
		}

		skb = skb->next;
		seq += mss;
	}
}

static void __tcpv4_gso_segment_csum(struct sk_buff *seg,
				     __be32 *oldip, __be32 newip,
				     __be16 *oldport, __be16 newport)
{
	struct tcphdr *th;
	struct iphdr *iph;

	if (*oldip == newip && *oldport == newport)
		return;

	th = tcp_hdr(seg);
	iph = ip_hdr(seg);

	inet_proto_csum_replace4(&th->check, seg, *oldip, newip, true);
	inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false);
	*oldport = newport;

	csum_replace4(&iph->check, *oldip, newip);
	*oldip = newip;
}

static struct sk_buff *__tcpv4_gso_segment_list_csum(struct sk_buff *segs)
{
	const struct tcphdr *th;
	const struct iphdr *iph;
	struct sk_buff *seg;
	struct tcphdr *th2;
	struct iphdr *iph2;

	seg = segs;
	th = tcp_hdr(seg);
	iph = ip_hdr(seg);
	th2 = tcp_hdr(seg->next);
	iph2 = ip_hdr(seg->next);

	if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) &&
	    iph->daddr == iph2->daddr && iph->saddr == iph2->saddr)
		return segs;

	while ((seg = seg->next)) {
		th2 = tcp_hdr(seg);
		iph2 = ip_hdr(seg);

		__tcpv4_gso_segment_csum(seg,
					 &iph2->saddr, iph->saddr,
					 &th2->source, th->source);
		__tcpv4_gso_segment_csum(seg,
					 &iph2->daddr, iph->daddr,
					 &th2->dest, th->dest);
	}

	return segs;
}

static struct sk_buff *__tcp4_gso_segment_list(struct sk_buff *skb,
					      netdev_features_t features)
{
	skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
	if (IS_ERR(skb))
		return skb;

	return __tcpv4_gso_segment_list_csum(skb);
}

static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
					netdev_features_t features)
{
	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
		return ERR_PTR(-EINVAL);

	if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
		return ERR_PTR(-EINVAL);

	if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) {
		struct tcphdr *th = tcp_hdr(skb);

		if ((skb_pagelen(skb) - th->doff * 4 == skb_shinfo(skb)->gso_size) &&
		    !(skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
			return __tcp4_gso_segment_list(skb, features);

Annotation

Implementation Notes