Tolerate ErrDumpInterrupted when listing tun addresses (#1835)

go.mod

@@ -23,7 +23,7 @@ require (
 	github.com/stretchr/testify v1.11.1
 	github.com/vishvananda/netlink v1.3.1
 	go.uber.org/goleak v1.3.0
-	go.yaml.in/yaml/v3 v3.0.5
+	go.yaml.in/yaml/v3 v3.0.4
 	golang.org/x/crypto v0.54.0
 	golang.org/x/exp v0.0.0-20230725093048-515e97ebf090
 	golang.org/x/net v0.57.0

go.sum

@@ -155,8 +155,8 @@ go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 go.yaml.in/yaml/v2 v2.4.2 h1:DzmwEr2rDGHl7lsFgAHxmNz/1NlQ7xLIrlN2h5d1eGI=
 go.yaml.in/yaml/v2 v2.4.2/go.mod h1:081UH+NErpNdqlCXm3TtEran0rJZGxAYx9hb/ELlsPU=
-go.yaml.in/yaml/v3 v3.0.5 h1:N6y/pJk8buWs9NY5ERU2HSMfm+IuD/OtfdAnq6kESPw=
-go.yaml.in/yaml/v3 v3.0.5/go.mod h1:HVTZu1O7/Vkt2N+BFy8Zza+lnLsABggaTM2ZpNIGuKg=
+go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
+go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=

overlay/tun_linux.go

@@ -5,6 +5,7 @@ package overlay
 
 import (
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
 	"log/slog"
@@ -483,7 +484,16 @@ func (t *tun) addIPs(link netlink.Link) error {
 	//iterate over remainder, remove whoever shouldn't be there
 	al, err := netlink.AddrList(link, netlink.FAMILY_ALL)
 	if err != nil {
-		return fmt.Errorf("failed to get tun address list: %s", err)
+		//RTM_GETADDR dumps the whole system, so any concurrent address change
+		//interrupts it - including the kernel's async tentative->preferred
+		//flip of an IPv6 address the AddrReplace calls above just added,
+		//which makes this a race against our own setup. Partial results are
+		//still returned; the worst case is a stale address surviving until
+		//the next config reload, which beats failing startup over it.
+		if !errors.Is(err, netlink.ErrDumpInterrupted) {
+			return fmt.Errorf("failed to get tun address list: %s", err)
+		}
+		t.l.Warn("tun address list dump was interrupted, stale addresses may remain")
 	}
 
 	for i := range al {