feat: update bootstrap_dns_android

transport/internet/system_dns_android.go

@@ -0,0 +1,28 @@
+// +build android
+
+package internet
+
+import (
+	"context"
+	"net"
+)
+
+type BootstrapDialerFunc func(context.Context, string, string) (net.Conn, error)
+
+func UseAlternativeBootstrapDNS(dialer BootstrapDialerFunc) {
+	net.DefaultResolver = &net.Resolver{
+		PreferGo: true,
+		Dial: dialer,
+	}
+}
+
+func init() {
+	const bootstrapDNS = "8.8.8.8:53"
+	var bootstrapDialer BootstrapDialerFunc = func(ctx context.Context, network, _ string) (net.Conn, error) {
+		var dialer net.Dialer
+		return dialer.DialContext(ctx, network, bootstrapDNS)
+	}
+	UseAlternativeBootstrapDNS(bootstrapDialer)
+
+	newError("Android Bootstrap DNS: ", bootstrapDNS).AtWarning().WriteToLog()
+}

transport/internet/system_dns_android_test.go

@@ -0,0 +1,32 @@
+// +build android
+
+package internet
+
+import (
+	"context"
+	"fmt"
+	gonet "net"
+	"testing"
+
+	"github.com/v2fly/v2ray-core/v4/common/net"
+)
+
+func TestBootstrapDNS(t *testing.T) {
+	if ips, err := gonet.LookupIP("www.google.com"); len(ips) == 0 {
+		t.Errorf("failed to lookupIP with BootstrapDNS, %v", err)
+	}
+}
+
+func TestBootstrapDNSWithV2raySystemDialer(t *testing.T) {
+	const bootstrapDNS = "8.8.4.4:53"
+	var bootstrapDialer BootstrapDialerFunc = func(ctx context.Context, network, _ string) (gonet.Conn, error) {
+		dest, err := net.ParseDestination(fmt.Sprintf("%s:%s", network, bootstrapDNS))
+		if err != nil {
+			return nil, err
+		}
+		return DialSystem(ctx, dest, nil)
+	}
+	UseAlternativeBootstrapDNS(bootstrapDialer)
+
+	TestBootstrapDNS(t)
+}