dtls.c: fix length checks in check_certificate_request.Add GET_VAR_FIELD.Signed-off-by: Achim Kraus <achim.kraus@cloudcoap.net>
dtls.c: fix length checks in SKIP_VAR_FIELD.Check for field length before reading the length to skip from the field.Signed-off-by: Achim Kraus <achim.kraus@cloudcoap.net>