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-rw-r--r--samples/bpf/parse_simple.c49
1 files changed, 49 insertions, 0 deletions
diff --git a/samples/bpf/parse_simple.c b/samples/bpf/parse_simple.c
new file mode 100644
index 000000000..4a486cb1e
--- /dev/null
+++ b/samples/bpf/parse_simple.c
@@ -0,0 +1,49 @@
+/* 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/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/bpf_helpers.h>
+
+#define DEFAULT_PKTGEN_UDP_PORT 9
+
+/* copy of 'struct ethhdr' without __packed */
+struct eth_hdr {
+ unsigned char h_dest[ETH_ALEN];
+ unsigned char h_source[ETH_ALEN];
+ unsigned short h_proto;
+};
+
+SEC("simple")
+int handle_ingress(struct __sk_buff *skb)
+{
+ void *data = (void *)(long)skb->data;
+ struct eth_hdr *eth = data;
+ struct iphdr *iph = data + sizeof(*eth);
+ struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph);
+ void *data_end = (void *)(long)skb->data_end;
+
+ /* single length check */
+ if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end)
+ return 0;
+
+ if (eth->h_proto != htons(ETH_P_IP))
+ return 0;
+ if (iph->protocol != IPPROTO_UDP || iph->ihl != 5)
+ return 0;
+ if (ip_is_fragment(iph))
+ return 0;
+ if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT))
+ return TC_ACT_SHOT;
+ return 0;
+}
+char _license[] SEC("license") = "GPL";