clone from danieldin95

pkg/libol/nl_linux.go

@@ -0,0 +1,45 @@
+package libol
+
+import (
+	"github.com/vishvananda/netlink"
+	"net"
+)
+
+func GetLocalByGw(addr string) (net.IP, error) {
+	local := net.IP{}
+	routes, err := netlink.RouteList(nil, netlink.FAMILY_V4)
+	if err != nil {
+		return nil, err
+	}
+	dest := net.ParseIP(addr)
+	if dest == nil {
+		Warn("GetLocalByGW: parseIP %s failed", addr)
+		return nil, nil
+	}
+	find := netlink.Route{LinkIndex: -1}
+	for _, rte := range routes {
+		if rte.Dst != nil && !rte.Dst.Contains(dest) {
+			continue
+		}
+		if find.LinkIndex != -1 && find.Priority < rte.Priority {
+			continue
+		}
+		find = rte
+	}
+	if find.LinkIndex != -1 {
+		index := find.LinkIndex
+		source := find.Gw
+		if source == nil {
+			source = find.Src
+		}
+		link, _ := netlink.LinkByIndex(index)
+		address, _ := netlink.AddrList(link, netlink.FAMILY_V4)
+		for _, ifAddr := range address {
+			if ifAddr.Contains(source) {
+				local = ifAddr.IP
+			}
+		}
+	}
+	Info("GetLocalByGw: find %s on %s", addr, local)
+	return local, nil
+}