To be able to fully read, understand and transfer RFCs into a standard-aligned application can be very difficult. You may become a lawyer as well.
We start off with section 2.1 of RFC 9460 which defines the following rules for us to apply:
- the record data must be formatted as “SvcPriority TargetName SvcParams” where
- SvcPriority is a number between 0 and 65535
- TargetName is a domain-name, which is a combination of texts (labels) that can contain alphabetic characters, digits and hyphens, these labels can be up to 63 characters each and can be bonded together using dots up to a length of 255 characters
- Note: The domain-name is not specified in RFC 9460, but already in RFC 1035
- SvcParam is one or more of either only a key such as ‘mykey’ or a key-value pair such as ‘mykey=”myvalue”‘ where the quotation mark is mandatory