Upstream Proxy: Skip proxy for some destinations

I’m in a corporate network where internet access is only possible through a proxy, so I have all the relevant environment variables set:

$ env | grep -i proxy | sort
http_proxy=http://proxy.corp:8888
HTTP_PROXY=http://proxy.corp:8888
https_proxy=http://proxy.corp:8888
HTTPS_PROXY=http://proxy.corp:8888
no_proxy=localhost,corp,127.0.0.1
NO_PROXY=localhost,corp,127.0.0.1

Now when I use mitmproxy, I can start it with --upstream-proxy $http_proxy and it will forward requests for public internet servers correctly, but it will fail with intranet servers, since it doesn’t see the $no_proxy variable. I see two options:

1. Add an option to fetch the upstream proxy from the various *_proxy environment variables.
2. Add an --upstream-proxy-skip option to support the $no_proxy usecase.

[scaradim]

+1

[ks07]

@mhils That looks ideal, thanks.