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// xdp_drop.go Drop incoming packets on XDP layer and count for which
// protocol type. Based on:
// https://github.com/iovisor/bcc/blob/master/examples/networking/xdp/xdp_drop_count.py
//
// Copyright (c) 2017 GustavoKatel
// Licensed under the Apache License, Version 2.0 (the "License")
package main
import (
"fmt"
"os"
"os/signal"
bpf "github.com/iovisor/gobpf/bcc"
)
/*
#cgo CFLAGS: -I/usr/include/bcc/compat
#cgo LDFLAGS: -lbcc
#include <bcc/bcc_common.h>
#include <bcc/libbpf.h>
void perf_reader_free(void *ptr);
*/
import "C"
const source string = `
#define KBUILD_MODNAME "foo"
#include <uapi/linux/bpf.h>
#include <linux/in.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
BPF_TABLE("array", int, long, dropcnt, 256);
static inline int parse_ipv4(void *data, u64 nh_off, void *data_end) {
struct iphdr *iph = data + nh_off;
if ((void*)&iph[1] > data_end)
return 0;
return iph->protocol;
}
static inline int parse_ipv6(void *data, u64 nh_off, void *data_end) {
struct ipv6hdr *ip6h = data + nh_off;
if ((void*)&ip6h[1] > data_end)
return 0;
return ip6h->nexthdr;
}
int xdp_prog1(struct CTXTYPE *ctx) {
void* data_end = (void*)(long)ctx->data_end;
void* data = (void*)(long)ctx->data;
struct ethhdr *eth = data;
// drop packets
int rc = RETURNCODE; // let pass XDP_PASS or redirect to tx via XDP_TX
long *value;
uint16_t h_proto;
uint64_t nh_off = 0;
int index;
nh_off = sizeof(*eth);
if (data + nh_off > data_end)
return rc;
h_proto = eth->h_proto;
// While the following code appears to be duplicated accidentally,
// it's intentional to handle double tags in ethernet frames.
if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
struct vlan_hdr *vhdr;
vhdr = data + nh_off;
nh_off += sizeof(struct vlan_hdr);
if (data + nh_off > data_end)
return rc;
h_proto = vhdr->h_vlan_encapsulated_proto;
}
if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
struct vlan_hdr *vhdr;
vhdr = data + nh_off;
nh_off += sizeof(struct vlan_hdr);
if (data + nh_off > data_end)
return rc;
h_proto = vhdr->h_vlan_encapsulated_proto;
}
if (h_proto == htons(ETH_P_IP))
index = parse_ipv4(data, nh_off, data_end);
else if (h_proto == htons(ETH_P_IPV6))
index = parse_ipv6(data, nh_off, data_end);
else
index = 0;
value = dropcnt.lookup(&index);
if (value) lock_xadd(value, 1);
return rc;
}
`
func usage() {
fmt.Printf("Usage: %v <ifdev>\n", os.Args[0])
fmt.Printf("e.g.: %v eth0\n", os.Args[0])
os.Exit(1)
}
func main() {
var device string
if len(os.Args) != 2 {
usage()
}
device = os.Args[1]
ret := "XDP_DROP"
ctxtype := "xdp_md"
module := bpf.NewModule(source, []string{
"-w",
"-DRETURNCODE=" + ret,
"-DCTXTYPE=" + ctxtype,
})
defer module.Close()
fn, err := module.Load("xdp_prog1", C.BPF_PROG_TYPE_XDP, 1, 65536)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to load xdp prog: %v\n", err)
os.Exit(1)
}
err = module.AttachXDP(device, fn)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to attach xdp prog: %v\n", err)
os.Exit(1)
}
defer func() {
if err := module.RemoveXDP(device); err != nil {
fmt.Fprintf(os.Stderr, "Failed to remove XDP from %s: %v\n", device, err)
}
}()
fmt.Println("Dropping packets, hit CTRL+C to stop")
sig := make(chan os.Signal, 1)
signal.Notify(sig, os.Interrupt, os.Kill)
dropcnt := bpf.NewTable(module.TableId("dropcnt"), module)
<-sig
fmt.Printf("\n{IP protocol-number}: {total dropped pkts}\n")
for it := dropcnt.Iter(); it.Next(); {
key := bpf.GetHostByteOrder().Uint32(it.Key())
value := bpf.GetHostByteOrder().Uint64(it.Leaf())
if value > 0 {
fmt.Printf("%v: %v pkts\n", key, value)
}
}
}
|
