1 #include <linux/bpf.h>
2 #include "bpf_helpers.h"
3 #include "bpf_util.h"
4 #include "bpf_endian.h"
5 
6 int _version SEC("version") = 1;
7 
8 #define bpf_printk(fmt, ...)					\
9 ({								\
10 	       char ____fmt[] = fmt;				\
11 	       bpf_trace_printk(____fmt, sizeof(____fmt),	\
12 				##__VA_ARGS__);			\
13 })
14 
15 SEC("sk_msg1")
16 int bpf_prog1(struct sk_msg_md *msg)
17 {
18 	void *data_end = (void *)(long) msg->data_end;
19 	void *data = (void *)(long) msg->data;
20 
21 	char *d;
22 
23 	if (data + 8 > data_end)
24 		return SK_DROP;
25 
26 	bpf_printk("data length %i\n", (__u64)msg->data_end - (__u64)msg->data);
27 	d = (char *)data;
28 	bpf_printk("hello sendmsg hook %i %i\n", d[0], d[1]);
29 
30 	return SK_PASS;
31 }
32 
33 char _license[] SEC("license") = "GPL";
34