Avoid ebpf lib usage on non Linux

client/internal/ebpf/dns_fwd_linux.go

@@ -0,0 +1,53 @@
+//go:build !android
+
+package ebpf
+
+import (
+	"encoding/binary"
+	"net"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	mapKeyDNSIP   uint32 = 0
+	mapKeyDNSPort uint32 = 1
+)
+
+func (tf *GeneralManager) LoadDNSFwd(ip string, dnsPort int) error {
+	log.Debugf("load ebpf DNS forwarder: address: %s:%d", ip, dnsPort)
+	tf.lock.Lock()
+	defer tf.lock.Unlock()
+
+	err := tf.loadXdp()
+	if err != nil {
+		return err
+	}
+
+	err = tf.bpfObjs.NbMapDnsIp.Put(mapKeyDNSIP, ip2int(ip))
+	if err != nil {
+		return err
+	}
+
+	err = tf.bpfObjs.NbMapDnsPort.Put(mapKeyDNSPort, uint16(dnsPort))
+	if err != nil {
+		return err
+	}
+
+	tf.setFeatureFlag(featureFlagDnsForwarder)
+	err = tf.bpfObjs.NbFeatures.Put(mapKeyFeatures, tf.featureFlags)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (tf *GeneralManager) FreeDNSFwd() error {
+	log.Debugf("free ebpf DNS forwarder")
+	return tf.unsetFeatureFlag(featureFlagDnsForwarder)
+}
+
+func ip2int(ipString string) uint32 {
+	ip := net.ParseIP(ipString)
+	return binary.BigEndian.Uint32(ip.To4())
+}