neighSubscribeAt: AF_BRIDGE entries not listed when listExisting is true

When subscribing to neigh updates, the updates for all neigh
protocol families are received. However when listExisting is set,
the request is made with AF_UNSPEC family, this request does not
include AF_BRIDGE entries.

This patch add a second request for AF_BRIDGE entries.

Signed-off-by: Nicolas Belouin <nicolas.belouin@gandi.net>

neigh_linux.go

@@ -337,6 +337,16 @@ func NeighSubscribeWithOptions(ch chan<- NeighUpdate, done <-chan struct{}, opti
 
 func neighSubscribeAt(newNs, curNs netns.NsHandle, ch chan<- NeighUpdate, done <-chan struct{}, cberr func(error), listExisting bool) error {
 	s, err := nl.SubscribeAt(newNs, curNs, unix.NETLINK_ROUTE, unix.RTNLGRP_NEIGH)
+	makeRequest := func(family int) error {
+		req := pkgHandle.newNetlinkRequest(unix.RTM_GETNEIGH,
+			unix.NLM_F_DUMP)
+		infmsg := nl.NewIfInfomsg(family)
+		req.AddData(infmsg)
+		if err := s.Send(req); err != nil {
+			return err
+		}
+		return nil
+	}
 	if err != nil {
 		return err
 	}
@@ -347,13 +357,10 @@ func neighSubscribeAt(newNs, curNs netns.NsHandle, ch chan<- NeighUpdate, done <
 		}()
 	}
 	if listExisting {
-		req := pkgHandle.newNetlinkRequest(unix.RTM_GETNEIGH,
-			unix.NLM_F_DUMP)
-		infmsg := nl.NewIfInfomsg(unix.AF_UNSPEC)
-		req.AddData(infmsg)
-		if err := s.Send(req); err != nil {
+		if err := makeRequest(unix.AF_UNSPEC); err != nil {
 			return err
 		}
+		// We have to wait for NLMSG_DONE before making AF_BRIDGE request
 	}
 	go func() {
 		defer close(ch)
@@ -367,6 +374,18 @@ func neighSubscribeAt(newNs, curNs netns.NsHandle, ch chan<- NeighUpdate, done <
 			}
 			for _, m := range msgs {
 				if m.Header.Type == unix.NLMSG_DONE {
+					if listExisting {
+						// This will be called after handling AF_UNSPEC
+						// list request, we have to wait for NLMSG_DONE
+						// before making another request
+						if err := makeRequest(unix.AF_BRIDGE); err != nil {
+							if cberr != nil {
+								cberr(err)
+							}
+							return
+						}
+						listExisting = false
+					}
 					continue
 				}
 				if m.Header.Type == unix.NLMSG_ERROR {