Failover: Support v6 gateway

Useful for v6 only VPNs

1 files changed, 18 insertions, 2 deletions

diff --git a/internal/failover/ping_default.go b/internal/failover/ping_default.go
index 11401bb..181f3fc 100644
--- a/internal/failover/ping_default.go
+++ b/internal/failover/ping_default.go
@@ -11,13 +11,29 @@ import (
 
 // NewPinger creates a new pinger with gateway `gateway` and size `size`
 func NewPinger(gateway string, size int) (*Pinger, error) {
-	l, err := icmp.ListenPacket("udp4", "0.0.0.0")
+	gip := net.ParseIP(gateway)
+	isV4 := gip.To4() != nil
+	mtuOverhead := mtuV6Overhead
+	if isV4 {
+		mtuOverhead = mtuV4Overhead
+	}
+	if size < mtuOverhead {
+		return nil, fmt.Errorf("invalid MTU size given, MTU has to be at least: %v bytes", mtuOverhead)
+	}
+	var l *icmp.PacketConn
+	var err error
+	if isV4 {
+		l, err = icmp.ListenPacket("udp4", "0.0.0.0")
+	} else {
+		l, err = icmp.ListenPacket("udp6", "::")
+	}
 	if err != nil {
 		return nil, fmt.Errorf("failed creating ping with error: %w", err)
 	}
 	return &Pinger{
 		listener: l,
 		buffer:   make([]byte, size-mtuOverhead),
-		gateway:  &net.UDPAddr{IP: net.ParseIP(gateway)},
+		gateway:  &net.UDPAddr{IP: gip},
+		v4:       isV4,
 	}, nil
 }