optimize: lower kernel version requirement from 5.6 to 5.2

component/control/bpf_utils.go

@@ -6,9 +6,12 @@
 package control
 
 import (
+	"fmt"
 	"github.com/cilium/ebpf"
 	"github.com/v2rayA/dae/common"
+	"github.com/v2rayA/dae/pkg/ebpf_internal"
 	"net/netip"
+	"reflect"
 )
 
 type _bpfLpmKey struct {
@@ -27,7 +30,7 @@ func (o *bpfObjects) newLpmMap(keys []_bpfLpmKey, values []uint32) (m *ebpf.Map,
 	if err != nil {
 		return nil, err
 	}
-	if _, err = m.BatchUpdate(keys, values, &ebpf.BatchOptions{
+	if _, err = BatchUpdate(m, keys, values, &ebpf.BatchOptions{
 		ElemFlags: uint64(ebpf.UpdateAny),
 	}); err != nil {
 		return nil, err
@@ -50,3 +53,47 @@ func cidrToBpfLpmKey(prefix netip.Prefix) _bpfLpmKey {
 		Data:      common.Ipv6ByteSliceToUint32Array(ip[:]),
 	}
 }
+
+// A utility to convert the values to proper strings.
+func int8ToStr(arr []int8) string {
+	b := make([]byte, 0, len(arr))
+	for _, v := range arr {
+		if v == 0x00 {
+			break
+		}
+		b = append(b, byte(v))
+	}
+	return string(b)
+}
+func BatchUpdate(m *ebpf.Map, keys interface{}, values interface{}, opts *ebpf.BatchOptions) (n int, err error) {
+	var old bool
+	version, e := internal.KernelVersion()
+	if e != nil || version.Less(internal.Version{5, 6, 0}) {
+		old = true
+	}
+	if !old {
+		return m.BatchUpdate(keys, values, opts)
+	} else {
+		vKeys := reflect.ValueOf(keys)
+		if vKeys.Kind() != reflect.Slice {
+			return 0, fmt.Errorf("keys must be slice")
+		}
+		vVals := reflect.ValueOf(values)
+		if vVals.Kind() != reflect.Slice {
+			return 0, fmt.Errorf("values must be slice")
+		}
+		length := vKeys.Len()
+		if vVals.Len() != length {
+			return 0, fmt.Errorf("keys and values must have same length")
+		}
+
+		for i := 0; i < length; i++ {
+			vKey := vKeys.Index(i)
+			vVal := vVals.Index(i)
+			if err = m.Update(vKey.Interface(), vVal.Interface(), ebpf.MapUpdateFlags(opts.ElemFlags)); err != nil {
+				return i, err
+			}
+		}
+		return vKeys.Len(), nil
+	}
+}