migrate to upstream libcompose in one and a half go

vendor/github.com/vishvananda/netlink/route_linux.go

@@ -14,23 +14,23 @@ import (
 // Equivalent to: `ip route add $route`
 func RouteAdd(route *Route) error {
 	req := nl.NewNetlinkRequest(syscall.RTM_NEWROUTE, syscall.NLM_F_CREATE|syscall.NLM_F_EXCL|syscall.NLM_F_ACK)
-	return routeHandle(route, req)
+	return routeHandle(route, req, nl.NewRtMsg())
 }
 
-// RouteAdd will delete a route from the system.
+// RouteDel will delete a route from the system.
 // Equivalent to: `ip route del $route`
 func RouteDel(route *Route) error {
 	req := nl.NewNetlinkRequest(syscall.RTM_DELROUTE, syscall.NLM_F_ACK)
-	return routeHandle(route, req)
+	return routeHandle(route, req, nl.NewRtDelMsg())
 }
 
-func routeHandle(route *Route, req *nl.NetlinkRequest) error {
+func routeHandle(route *Route, req *nl.NetlinkRequest, msg *nl.RtMsg) error {
 	if (route.Dst == nil || route.Dst.IP == nil) && route.Src == nil && route.Gw == nil {
 		return fmt.Errorf("one of Dst.IP, Src, or Gw must not be nil")
 	}
 
-	msg := nl.NewRtMsg()
 	msg.Scope = uint8(route.Scope)
+	msg.Flags = uint32(route.Flags)
 	family := -1
 	var rtAttrs []*nl.RtAttr
 
@@ -118,8 +118,7 @@ func RouteList(link Link, family int) ([]Route, error) {
 		index = base.Index
 	}
 
-	native := nl.NativeEndian()
-	res := make([]Route, 0)
+	var res []Route
 	for _, m := range msgs {
 		msg := nl.DeserializeRtMsg(m)
 
@@ -133,31 +132,14 @@ func RouteList(link Link, family int) ([]Route, error) {
 			continue
 		}
 
-		attrs, err := nl.ParseRouteAttr(m[msg.Len():])
+		route, err := deserializeRoute(m)
 		if err != nil {
 			return nil, err
 		}
 
-		route := Route{Scope: Scope(msg.Scope)}
-		for _, attr := range attrs {
-			switch attr.Attr.Type {
-			case syscall.RTA_GATEWAY:
-				route.Gw = net.IP(attr.Value)
-			case syscall.RTA_PREFSRC:
-				route.Src = net.IP(attr.Value)
-			case syscall.RTA_DST:
-				route.Dst = &net.IPNet{
-					IP:   attr.Value,
-					Mask: net.CIDRMask(int(msg.Dst_len), 8*len(attr.Value)),
-				}
-			case syscall.RTA_OIF:
-				routeIndex := int(native.Uint32(attr.Value[0:4]))
-				if link != nil && routeIndex != index {
-					// Ignore routes from other interfaces
-					continue
-				}
-				route.LinkIndex = routeIndex
-			}
+		if link != nil && route.LinkIndex != index {
+			// Ignore routes from other interfaces
+			continue
 		}
 		res = append(res, route)
 	}
@@ -165,6 +147,37 @@ func RouteList(link Link, family int) ([]Route, error) {
 	return res, nil
 }
 
+// deserializeRoute decodes a binary netlink message into a Route struct
+func deserializeRoute(m []byte) (Route, error) {
+	route := Route{}
+	msg := nl.DeserializeRtMsg(m)
+	attrs, err := nl.ParseRouteAttr(m[msg.Len():])
+	if err != nil {
+		return route, err
+	}
+	route.Scope = Scope(msg.Scope)
+	route.Flags = int(msg.Flags)
+
+	native := nl.NativeEndian()
+	for _, attr := range attrs {
+		switch attr.Attr.Type {
+		case syscall.RTA_GATEWAY:
+			route.Gw = net.IP(attr.Value)
+		case syscall.RTA_PREFSRC:
+			route.Src = net.IP(attr.Value)
+		case syscall.RTA_DST:
+			route.Dst = &net.IPNet{
+				IP:   attr.Value,
+				Mask: net.CIDRMask(int(msg.Dst_len), 8*len(attr.Value)),
+			}
+		case syscall.RTA_OIF:
+			routeIndex := int(native.Uint32(attr.Value[0:4]))
+			route.LinkIndex = routeIndex
+		}
+	}
+	return route, nil
+}
+
 // RouteGet gets a route to a specific destination from the host system.
 // Equivalent to: 'ip route get'.
 func RouteGet(destination net.IP) ([]Route, error) {
@@ -192,34 +205,47 @@ func RouteGet(destination net.IP) ([]Route, error) {
 		return nil, err
 	}
 
-	native := nl.NativeEndian()
-	res := make([]Route, 0)
+	var res []Route
 	for _, m := range msgs {
-		msg := nl.DeserializeRtMsg(m)
-		attrs, err := nl.ParseRouteAttr(m[msg.Len():])
+		route, err := deserializeRoute(m)
 		if err != nil {
 			return nil, err
 		}
-
-		route := Route{}
-		for _, attr := range attrs {
-			switch attr.Attr.Type {
-			case syscall.RTA_GATEWAY:
-				route.Gw = net.IP(attr.Value)
-			case syscall.RTA_PREFSRC:
-				route.Src = net.IP(attr.Value)
-			case syscall.RTA_DST:
-				route.Dst = &net.IPNet{
-					IP:   attr.Value,
-					Mask: net.CIDRMask(int(msg.Dst_len), 8*len(attr.Value)),
-				}
-			case syscall.RTA_OIF:
-				routeIndex := int(native.Uint32(attr.Value[0:4]))
-				route.LinkIndex = routeIndex
-			}
-		}
 		res = append(res, route)
 	}
 	return res, nil
 
 }
+
+// RouteSubscribe takes a chan down which notifications will be sent
+// when routes are added or deleted. Close the 'done' chan to stop subscription.
+func RouteSubscribe(ch chan<- RouteUpdate, done <-chan struct{}) error {
+	s, err := nl.Subscribe(syscall.NETLINK_ROUTE, syscall.RTNLGRP_IPV4_ROUTE, syscall.RTNLGRP_IPV6_ROUTE)
+	if err != nil {
+		return err
+	}
+	if done != nil {
+		go func() {
+			<-done
+			s.Close()
+		}()
+	}
+	go func() {
+		defer close(ch)
+		for {
+			msgs, err := s.Receive()
+			if err != nil {
+				return
+			}
+			for _, m := range msgs {
+				route, err := deserializeRoute(m.Data)
+				if err != nil {
+					return
+				}
+				ch <- RouteUpdate{Type: m.Header.Type, Route: route}
+			}
+		}
+	}()
+
+	return nil
+}