samples/bpf/parse_varlen.c

Source file repositories/reference/linux-study-clean/samples/bpf/parse_varlen.c

File Facts

System
Linux kernel
Corpus path
samples/bpf/parse_varlen.c
Extension
.c
Size
3487 bytes
Lines
151
Domain
Support Tooling And Documentation
Bucket
samples
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

if (DEBUG) {
			char fmt[] = "udp port 9 indeed\n";

			bpf_trace_printk(fmt, sizeof(fmt));
		}
		return TC_ACT_SHOT;
	}
	return 0;
}

static int parse_ipv4(void *data, uint64_t nh_off, void *data_end)
{
	struct iphdr *iph;
	uint64_t ihl_len;

	iph = data + nh_off;
	if (iph + 1 > data_end)
		return 0;

	if (ip_is_fragment(iph))
		return 0;
	ihl_len = iph->ihl * 4;

	if (iph->protocol == IPPROTO_IPIP) {
		iph = data + nh_off + ihl_len;
		if (iph + 1 > data_end)
			return 0;
		ihl_len += iph->ihl * 4;
	}

	if (iph->protocol == IPPROTO_TCP)
		return tcp(data, nh_off + ihl_len, data_end);
	else if (iph->protocol == IPPROTO_UDP)
		return udp(data, nh_off + ihl_len, data_end);
	return 0;
}

static int parse_ipv6(void *data, uint64_t nh_off, void *data_end)
{
	struct ipv6hdr *ip6h;
	struct iphdr *iph;
	uint64_t ihl_len = sizeof(struct ipv6hdr);
	uint64_t nexthdr;

	ip6h = data + nh_off;
	if (ip6h + 1 > data_end)
		return 0;

	nexthdr = ip6h->nexthdr;

	if (nexthdr == IPPROTO_IPIP) {
		iph = data + nh_off + ihl_len;
		if (iph + 1 > data_end)
			return 0;
		ihl_len += iph->ihl * 4;
		nexthdr = iph->protocol;
	} else if (nexthdr == IPPROTO_IPV6) {
		ip6h = data + nh_off + ihl_len;
		if (ip6h + 1 > data_end)
			return 0;
		ihl_len += sizeof(struct ipv6hdr);
		nexthdr = ip6h->nexthdr;
	}

	if (nexthdr == IPPROTO_TCP)
		return tcp(data, nh_off + ihl_len, data_end);
	else if (nexthdr == IPPROTO_UDP)
		return udp(data, nh_off + ihl_len, data_end);
	return 0;
}

SEC("varlen")
int handle_ingress(struct __sk_buff *skb)
{
	void *data = (void *)(long)skb->data;
	struct ethhdr *eth = data;
	void *data_end = (void *)(long)skb->data_end;
	uint64_t h_proto, nh_off;

	nh_off = sizeof(*eth);
	if (data + nh_off > data_end)
		return 0;

	h_proto = eth->h_proto;

	if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) {
		struct vlan_hdr *vhdr;

		vhdr = data + nh_off;
		nh_off += sizeof(struct vlan_hdr);

Annotation

Implementation Notes