- Add XDP support (@Hevienz)

- `bpf_xdp_attach`

- `bpf_xdp_detach`

xdp_counter: build

sudo $(CWD)/xdp_counter.exe

(names tc bootstrap bootstrap_c kprobe minimal xdp_counter)

(rule

(mode

(promote (until-clean)))

(targets xdp_counter.bpf.o)

(deps arch xdp_counter.bpf.c)

(action

(system

"clang -g -O2 -target bpf -I/usr/include/%{architecture}-linux-gnu/ -c xdp_counter.bpf.c -D__TARGET_ARCH_%{read:arch}")))

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

struct {

__uint(type, BPF_MAP_TYPE_ARRAY);

__uint(max_entries, 1);

__type(key, int);

__type(value, unsigned long);

} packet_count SEC(".maps");

SEC("xdp")

int count_packets(struct xdp_md *ctx) {

int key = 0;

unsigned long *value;

value = bpf_map_lookup_elem(&packet_count, &key);

if (value)

__sync_fetch_and_add(value, 1);

return XDP_PASS;

}

char _license[] SEC("license") = "GPL";

open Libbpf

let obj_path = "xdp_counter.bpf.o"

let program_name = "count_packets"

let map = "packet_count"

let ifindex = 1 (* Usually localhost *)

let load_and_attach_xdp ifindex =

(* Load the compiled eBPF object *)

let obj = bpf_object_open obj_path in

let _ = bpf_object_load obj in

let program = bpf_object_find_program_by_name obj program_name in

let fd = bpf_program_fd program in

let opts = Ctypes.from_voidp C.Types.Bpf_xdp.Attach_opts.t Ctypes.null in

(match C.Functions.bpf_xdp_attach ifindex fd Unsigned.UInt32.zero opts with

| 0 -> ()

| _ ->

bpf_object_close obj;

failwith "Failed to attach xdp program");

(obj, opts)

let teardown_xdp (obj, link) =

let _ = C.Functions.bpf_xdp_detach 0 Unsigned.UInt32.zero link in

bpf_object_close obj

let () =

let obj, link = load_and_attach_xdp ifindex in

(* Initialize bpf_map with value, if not the lookup will fail *)

let counter = bpf_object_find_map_by_name obj map in

let exitting = ref false in

let sig_handler = Sys.Signal_handle (fun _ -> exitting := true) in

Sys.(set_signal sigint sig_handler);

Sys.(set_signal sigterm sig_handler);

let rec loop () =

if !exitting then ()

else (

Unix.sleep 1;

let count =

bpf_map_lookup_value ~key_ty:Ctypes.int ~val_ty:Ctypes.ulong

~val_zero:Unsigned.ULong.zero counter 0

in

Printf.printf "Packet count %d\n%!" (Unsigned.ULong.to_int count);

loop ())

in

loop ();

teardown_xdp (obj, link)

(* ================================== Xdp ================================== *)

let bpf_xdp_attach =

foreign "bpf_xdp_attach"

(int @-> int @-> uint32_t

@-> ptr Types.Bpf_xdp.Attach_opts.t

@-> returning int)

let bpf_xdp_detach =

foreign "bpf_xdp_detach"

(int @-> uint32_t @-> ptr Types.Bpf_xdp.Attach_opts.t @-> returning int)

module Bpf_xdp = struct

module Attach_opts = struct

let t : [ `Attach_opts ] structure typ = structure "bpf_xdp_attach_opts"

let ( -: ) ty label = field t label ty

let sz = size_t -: "sz"

let old_prog_fd = int -: "old_prog_fd"

let () = seal t

end

end

"ocaml_libbpf.1.1": [

"bpf_xdp_attach",

"bpf_xdp_detach"

],