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Add support for MTU option overrides #8

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Add support for MTU option overrides #8

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19 changes: 19 additions & 0 deletions main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,17 @@ import (
"github.com/vishvananda/netlink"
)

const (
omitMTU = 0
deviceMTU = -1
)

var (
flagMTU = flag.Int(
"mtu",
omitMTU,
fmt.Sprintf("configure the MTU value that is sent. %d (default) = disable MTU option, %d = use MTU of the interface device, >0 = send the provided value as the MTU option.", omitMTU, deviceMTU),
)
flagLifeTime = flag.Duration("lifetime", (30 * time.Minute), "Lifetime (prefix valid time will be 3x lifetime).")
flagInterval = flag.Duration("interval", (5 * time.Minute), "Frequency of *un*solicitated RAs.")
errRetry = errors.New("retry")
Expand Down Expand Up @@ -81,6 +91,15 @@ func main() {
ll.Infof("Loglevel '%s'", ll.GetLevel())
ll.Infof("Sending RAs valid for %v every %v on interfaces matching %s", *flagLifeTime, *flagInterval, *flagTapRegex)
ll.Infof("Excluding %s from RAs", exclude)
if *flagMTU == deviceMTU {
ll.Infoln("MTU Option: interface determined")
} else if *flagMTU == omitMTU {
ll.Infoln("MTU Option disabled")
} else if *flagMTU > omitMTU {
ll.Infof("MTU Option: %v", *flagMTU)
} else {
ll.Infof("MTU Option: invalid value %d", *flagMTU)
}

if flagLifeTime.Seconds() < 3*(flagInterval.Seconds()) {
ll.Warnf(
Expand Down
7 changes: 6 additions & 1 deletion ra.go
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,12 @@ func (t Tap) sendLoop(ctx context.Context, c *ndp.Conn) error {
Direction: ndp.Source,
Addr: t.Ifi.HardwareAddr,
},
ndp.NewMTU(uint32(t.Ifi.MTU)),
}

if *flagMTU == deviceMTU {
options = append(options, ndp.NewMTU(uint32(t.Ifi.MTU)))
} else if *flagMTU > omitMTU {
options = append(options, ndp.NewMTU(uint32(*flagMTU)))
}

if t.Prefix != nil {
Expand Down