Fixes #7690: Use classic protocol in Rudder 3.2

[amousset]

https://www.rudder-project.org/redmine/issues/7690

[peckpeck]

OK, good, but why not in 2.11 ? especially for system techniques

[peckpeck]

Lets backport it later

[ncharles]

protocl_version was introduced in 3.6, so won't work on 3.5
We need to keep the compatibility with previous version of Rudder in Rudder <3.1 (unless stated otherwise)
So only Rudder 3.2 will have this fix

[peckpeck]

2.11 if cfengine 3.6
And older server will give their promises to newer agents from their system techniques, so newer agent won't be able to talk to older server.

[ncharles]

@peckpeck no, server 2.11 may still server agent 2.10, and so it will break.

[ncharles]

and if you use agent 3.2 with server 2.11, it will use classic protocol, same for agent 3.1 with server 3.2

[peckpeck]

It detects the server version before choosing the protocol ?

[ncharles]

CFEngine 3.6 uses classical by defaut.
If any of the two use classical, the protocol used is classical

[peckpeck]

ok

[ncharles]

this is why agent 3.1 + server 3.2 works with NAT system, but without this patch, agent 3.2 and server 3.2 does not

[amousset]

yes but agent 3.2 with any server from 2.11 will use TLS as it is supported by the server.