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a80857822b
this example does the same task as previous socket example
in assembler, but this one does it in C.
eBPF program in kernel does:
/* assume that packet is IPv4, load one byte of IP->proto */
int index = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));
long *value;
value = bpf_map_lookup_elem(&my_map, &index);
if (value)
__sync_fetch_and_add(value, 1);
Corresponding user space reads map[tcp], map[udp], map[icmp]
and prints protocol stats every second
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
50 lines
981 B
C
50 lines
981 B
C
#include <stdio.h>
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#include <assert.h>
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#include <linux/bpf.h>
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#include "libbpf.h"
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#include "bpf_load.h"
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#include <unistd.h>
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#include <arpa/inet.h>
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int main(int ac, char **argv)
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{
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char filename[256];
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FILE *f;
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int i, sock;
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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if (load_bpf_file(filename)) {
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printf("%s", bpf_log_buf);
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return 1;
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}
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sock = open_raw_sock("lo");
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assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, prog_fd,
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sizeof(prog_fd[0])) == 0);
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f = popen("ping -c5 localhost", "r");
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(void) f;
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for (i = 0; i < 5; i++) {
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long long tcp_cnt, udp_cnt, icmp_cnt;
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int key;
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key = IPPROTO_TCP;
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assert(bpf_lookup_elem(map_fd[0], &key, &tcp_cnt) == 0);
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key = IPPROTO_UDP;
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assert(bpf_lookup_elem(map_fd[0], &key, &udp_cnt) == 0);
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key = IPPROTO_ICMP;
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assert(bpf_lookup_elem(map_fd[0], &key, &icmp_cnt) == 0);
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printf("TCP %lld UDP %lld ICMP %lld packets\n",
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tcp_cnt, udp_cnt, icmp_cnt);
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sleep(1);
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}
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return 0;
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}
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