whatcanGOwrong

go/pkg/mod/github.com/cilium/ebpf@v0.11.0/examples/xdp/main.go

@@ -0,0 +1,84 @@
+// This program demonstrates attaching an eBPF program to a network interface
+// with XDP (eXpress Data Path). The program parses the IPv4 source address
+// from packets and writes the packet count by IP to an LRU hash map.
+// The userspace program (Go code in this file) prints the contents
+// of the map to stdout every second.
+// It is possible to modify the XDP program to drop or redirect packets
+// as well -- give it a try!
+// This example depends on bpf_link, available in Linux kernel version 5.7 or newer.
+package main
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/cilium/ebpf"
+	"github.com/cilium/ebpf/link"
+)
+
+// $BPF_CLANG and $BPF_CFLAGS are set by the Makefile.
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -cc $BPF_CLANG -cflags $BPF_CFLAGS bpf xdp.c -- -I../headers
+
+func main() {
+	if len(os.Args) < 2 {
+		log.Fatalf("Please specify a network interface")
+	}
+
+	// Look up the network interface by name.
+	ifaceName := os.Args[1]
+	iface, err := net.InterfaceByName(ifaceName)
+	if err != nil {
+		log.Fatalf("lookup network iface %q: %s", ifaceName, err)
+	}
+
+	// Load pre-compiled programs into the kernel.
+	objs := bpfObjects{}
+	if err := loadBpfObjects(&objs, nil); err != nil {
+		log.Fatalf("loading objects: %s", err)
+	}
+	defer objs.Close()
+
+	// Attach the program.
+	l, err := link.AttachXDP(link.XDPOptions{
+		Program:   objs.XdpProgFunc,
+		Interface: iface.Index,
+	})
+	if err != nil {
+		log.Fatalf("could not attach XDP program: %s", err)
+	}
+	defer l.Close()
+
+	log.Printf("Attached XDP program to iface %q (index %d)", iface.Name, iface.Index)
+	log.Printf("Press Ctrl-C to exit and remove the program")
+
+	// Print the contents of the BPF hash map (source IP address -> packet count).
+	ticker := time.NewTicker(1 * time.Second)
+	defer ticker.Stop()
+	for range ticker.C {
+		s, err := formatMapContents(objs.XdpStatsMap)
+		if err != nil {
+			log.Printf("Error reading map: %s", err)
+			continue
+		}
+		log.Printf("Map contents:\n%s", s)
+	}
+}
+
+func formatMapContents(m *ebpf.Map) (string, error) {
+	var (
+		sb  strings.Builder
+		key []byte
+		val uint32
+	)
+	iter := m.Iterate()
+	for iter.Next(&key, &val) {
+		sourceIP := net.IP(key) // IPv4 source address in network byte order.
+		packetCount := val
+		sb.WriteString(fmt.Sprintf("\t%s => %d\n", sourceIP, packetCount))
+	}
+	return sb.String(), iter.Err()
+}