add dhcp failing test

dhcpv4/definitions.go

@@ -2,6 +2,7 @@ package dhcpv4
 
 import (
 	"errors"
+	"unsafe"
 )
 
 //go:generate stringer -type=OptNum,Op,MessageType,ClientState -linecomment -output stringers.go
@@ -38,6 +39,11 @@ func AppendOption(dst []byte, opt OptNum, data ...byte) []byte {
 	return dst
 }
 
+func AppendOptionString(dst []byte, opt OptNum, data string) []byte {
+	bdata := unsafe.Slice(unsafe.StringData(data), len(data))
+	return AppendOption(dst, opt, bdata...)
+}
+
 func EncodeOption(dst []byte, opt OptNum, data ...byte) (int, error) {
 	if len(data) > 255 {
 		return 0, errors.New("DHCPv4 option data too long (>255)")