v4.19.13 snapshot.
diff --git a/samples/bpf/parse_varlen.c b/samples/bpf/parse_varlen.c
new file mode 100644
index 0000000..0b6f22f
--- /dev/null
+++ b/samples/bpf/parse_varlen.c
@@ -0,0 +1,150 @@
+/* Copyright (c) 2016 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#define KBUILD_MODNAME "foo"
+#include <linux/if_ether.h>
+#include <linux/if_vlan.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/in.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <uapi/linux/bpf.h>
+#include <net/ip.h>
+#include "bpf_helpers.h"
+
+#define DEFAULT_PKTGEN_UDP_PORT 9
+#define DEBUG 0
+
+static int tcp(void *data, uint64_t tp_off, void *data_end)
+{
+ struct tcphdr *tcp = data + tp_off;
+
+ if (tcp + 1 > data_end)
+ return 0;
+ if (tcp->dest == htons(80) || tcp->source == htons(80))
+ return TC_ACT_SHOT;
+ return 0;
+}
+
+static int udp(void *data, uint64_t tp_off, void *data_end)
+{
+ struct udphdr *udp = data + tp_off;
+
+ if (udp + 1 > data_end)
+ return 0;
+ if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT) ||
+ udp->source == htons(DEFAULT_PKTGEN_UDP_PORT)) {
+ 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);
+ if (data + nh_off > data_end)
+ return 0;
+ h_proto = vhdr->h_vlan_encapsulated_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);
+ if (data + nh_off > data_end)
+ return 0;
+ h_proto = vhdr->h_vlan_encapsulated_proto;
+ }
+ if (h_proto == htons(ETH_P_IP))
+ return parse_ipv4(data, nh_off, data_end);
+ else if (h_proto == htons(ETH_P_IPV6))
+ return parse_ipv6(data, nh_off, data_end);
+ return 0;
+}
+char _license[] SEC("license") = "GPL";