AMQP 0-9-1 connections: accommodate longer JWT tokens #13541
Description
Is your feature request related to a problem? Please describe.
connection.start-ok's SASL response field was not originally designed for JWT
tokens, which can be longer than, say, a typical string length of 256 bytes.
It's not common to see JWT tokens that exceed the length limit and
force the AMQP 0-9-1 parser to consider the frame to be too long,
it would be nice to see if the limit can be increased to, say, 8192 bytes in a backwards-compatible way.
With many HTTP servers, the limit is that of a header length, which seems to be around 8192 bytes, for example, that's the value mentioned in large_client_header_buffers documentation in Nginx.
See #13537 for one example.
Describe the solution you'd like
If feasible in terms of backwards compatibility, AMQP 0-9-1's connection.start-ok's response field should allow for longer payloads.
Describe alternatives you've considered
The only alternative seems to be adding an early validation of the password/secret field length in client libraries, plus an extension to the OAuth 2 Troubleshooting guide: rabbitmq/rabbitmq-website#2212.
Additional context
No response