feat: As user, I want to process empty ssl_server_name, so that I solve error

[tom5897]

Description

In OCI load balancer, Oracle, MTLS is not supported between OCI load balancer to backend server.
https://docs.oracle.com/en-us/iaas/Content/Balance/Tasks/managinglisteners_topic-Creating_Listeners.htm

So, I met error by empty SSL SNI($ssl_server_name in nginx).
[lua] init.lua:185: http_ssl_client_hello_phase(): failed to find SNI: please check if the client requests via IP or uses an outdated protocol. If you need to report an issue, provide a packet capture file of the TLS handshake., context: ssl_client_hello_by_lua*

If SSL SNI is empty, I want to use another variable, like hostname, $host for solving this error.

[bzp2010]

The $host variable won't exist until a TLS connection is established (complete with handshake), and the connection has already been rejected and closed due to a empty SNI before then, so the scenario you mention isn't directly feasible.

$host is used for HTTP, the HTTP doesn't exist before the TLS connection is established, so it's not possible.

We have another solution, check the fallback_sni entry in the config file.
This allows you to specify a default value when LB passes an empty SNI, which will solve your problem.

apisix/conf/config.yaml.example

Line 111 in de7bd0b

# fallback_sni: "my.default.domain" # Fallback SNI to be used if the client does not send SNI during

Note that this is not complete, you must also configure an SSL resource for this specified SNI, which you secure the communication by using a self-signed certificate and trusting it on the LB.

[tom5897]

I understand that SSL SNI variable is an essential.