Our app interfaces with our web server using the HTTP components of WinINet, and in the past, we've had issues with this on certain corporate networks. For example, I couldn't append additional HTTP headers or their proxy would drop the requests. Things are working fine currently, but that's after a lot of difficult debugging.
We have now set up an SSL certificate and enabled our app to use HTTPS, and things seem smooth and great, but I am not convinced such a change is going to work out smoothly for these corporate networks. Would it be reasonable for a firewall to block SSL traffic? Are there any hidden 'gotchas' when it comes to SSL going through a proxy? Would it be worth it to configure the WinINet calls to fall back to HTTP if the HTTPS connection fails?
I'm just mainly interested in what I need to look out for and avoid, in the interest of making this as compatible as possible in the face of unseen network/firewall/proxy hurdles.