1 files changed, 72 insertions, 0 deletions
diff --git a/internal/pkg/config/default_linux.go b/internal/pkg/config/default_linux.go
new file mode 100644
index 00000000..8cfcc501
--- /dev/null
+++ b/internal/pkg/config/default_linux.go
@@ -0,0 +1,72 @@
+// Copyright (C) 2016 Nippon Telegraph and Telephone Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+// implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// +build linux
+
+package config
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/vishvananda/netlink"
+)
+
+func GetIPv6LinkLocalNeighborAddress(ifname string) (string, error) {
+	ifi, err := net.InterfaceByName(ifname)
+	if err != nil {
+		return "", err
+	}
+	neighs, err := netlink.NeighList(ifi.Index, netlink.FAMILY_V6)
+	if err != nil {
+		return "", err
+	}
+	cnt := 0
+	var addr net.IP
+	for _, neigh := range neighs {
+		local, err := isLocalLinkLocalAddress(ifi.Index, neigh.IP)
+		if err != nil {
+			return "", err
+		}
+		if neigh.State&netlink.NUD_FAILED == 0 && neigh.IP.IsLinkLocalUnicast() && !local {
+			addr = neigh.IP
+			cnt++
+		}
+	}
+
+	if cnt == 0 {
+		return "", fmt.Errorf("no ipv6 link-local neighbor found")
+	} else if cnt > 1 {
+		return "", fmt.Errorf("found %d link-local neighbors. only support p2p link", cnt)
+	}
+
+	return fmt.Sprintf("%s%%%s", addr, ifname), nil
+}
+
+func isLocalLinkLocalAddress(ifindex int, addr net.IP) (bool, error) {
+	ifi, err := net.InterfaceByIndex(ifindex)
+	if err != nil {
+		return false, err
+	}
+	addrs, err := ifi.Addrs()
+	if err != nil {
+		return false, err
+	}
+	for _, a := range addrs {
+		if ip, _, _ := net.ParseCIDR(a.String()); addr.Equal(ip) {
+			return true, nil
+		}
+	}
+	return false, nil
+}