BPF consume_skb loader

load_skb_bpf.c

#include <signal.h>
#include <stdio.h>
#include <time.h>
#include <sys/resource.h>
#include <bpf/libbpf.h>
#include "skb.skel.h"

static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
{
	if (level == LIBBPF_DEBUG)
		return 0;
	return vfprintf(stderr, format, args);
}

int main(int argc, char **argv)
{
	struct skb_bpf *skel;
	int err;

	libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
	/* Set up libbpf errors and debug info callback */
	libbpf_set_print(libbpf_print_fn);

	/* Load and verify BPF application */
	skel = skb_bpf__open();
	if (!skel) {
		fprintf(stderr, "Failed to open and load BPF skeleton\n");
		return 1;
	}

	/* Load & verify BPF programs */
	err = skb_bpf__load(skel);
	if (err) {
		fprintf(stderr, "Failed to load and verify BPF skeleton\n");
		goto cleanup;
	}

	/* Attach tracepoints */
	err = skb_bpf__attach(skel);
	if (err) {
		fprintf(stderr, "Failed to attach BPF skeleton\n");
		goto cleanup;
	}

	int fmap = bpf_map__fd(skel->maps.fmap);
	if (!fmap) {
		err = -1;
		fprintf(stderr, "Failed to create ring buffer\n");
		goto cleanup;
	}

	int *val;
	const int zero = 0;
	int i = 0;
	while (true) {
		bpf_map_lookup_elem(fmap, &zero, &val);
		if (&val == 1) {
			bpf_map_update_elem(fmap, &zero, &zero, BPF_ANY);
		}
		printf("%d\n",val);
	}

cleanup:
	/* Clean up */
	skb_bpf__destroy(skel);

	return 0;
}