TLS handshake with kafka docker broker failed with the format of [ip]:port for IPv4 address

[yeliangyl]

I use librdkafka as client lib to connect to docker kafka broker through tls connection. We need to support both IPv4 and IPv6. So the broker address was set to [ip]:port, like [10.4.1000.35]:9094. One problem I encountered was the tls handshake failed and the error returned from the server side was Illegal Parameter. A SNI=[10.4.1000.35] is carried with Client Hello message. After changing the address to 10.4.100.35:9094, tls connection was successful and no SNI in Client Hello.

I tried openssl command directly on the same system and can connect to the broker as well. No SNI in client hello message
openssl s_client -connect [10.4.100.35]:9094 -CApath ... -key ...

So not sure who populated SNI in the hello message, librdkafka or openssl? And how to set broker address if want to support both IPv4 and IPv6.