Enable the proxy_ssl_server_name option

[ankon]

This fixes #31

Note that this is currently on top of #30, but that isn't required.

[hone]

Thanks for the patch. the proxy stuff definitely needs some more work/cleanup. Can you split this from #30? Also, is there cases where you wouldn't want this option enabled?

[ankon]

As far as I understand the option: it would now send some additional data in the first request, which the origin can use to select the correct certificate, or ignore it.

Re splitting: sure, will rebase this onto master then.

[jmervine]

👍 for making it on by default... perhaps support disabling via config?

[hone]

@jmervine @ankon are there cases where you wouldn't want this on?

[jmervine]

@hone I can't specifically think of one, but I feel like Nginx would make it on by default if there weren't some obvious reason not to. If nothing else, performance perhaps, when it's not needed, but that's probably marginal.

[jmervine]

@rdsharma

[wcurtis]

Bump - any timeline on getting this in? We could sure use it.

[ojacobson]

As I understand it, this PR enables the presentation of SNI information when Nginx connects to proxy backends. This is a good thing, in 2016: SNI is widespread. So long as the hostname included in the presented SNI handshake comes from the proxy backend URL, and not from the client's Host: header - that is, so long as backends perceive requests as being meant for the host in the backend URL, and not the host of the proxy itself - then this is the right fix.

I believe that's exactly what the named option does. Merging.