Fix dtls hash creation and allow empty tlsa_ttl

[pkolmann]

Hi @alainwolf

thanks for this script. I started using it in one of my domains and found that it failed all DANE online checks.

After checking https://github.com/cpcloudnl/dane-smtp#generate-the-sha2-256-hash-based-on-the-spki I found that you strip '\0' from the DER encoded cert. This alters the certificate and therefore also the hash.

I asked chatgpt to help me to improve your script.

Also I didn't specify tlsa_ttl as specified in the top and dnsutil failed to process.

I have updated my zone with this new script and now DANE checks are successful:

• https://www.uriports.com/tools/dane-validator
• https://testconnectivity.microsoft.com/tests/O365DaneValidation/input

Does your script work for you? Do I have some bug in by setup?

thanks Philipp