HTTP connect requests with downstream proxy timing out

[pieterja...@gmail.com]

I'm trying to setup an HTTP proxy server with martian that directs HTTPS requests via the CONNECT method. I configured a downstream proxy address, so the tunnel should be set up via this proxy, like so:

https://github.com/google/martian/blob/master/proxy.go#L467-L486

I get no errors on that part (status 200 is returned by the host), however my code blocks on this line:

https://github.com/google/martian/blob/master/proxy.go#L390

Followed by an error:

read tcp MY_IP:52638->PROXY_IP:60000: read tcp 127.0.0.1:9999->127.0.0.1:52637: i/o timeout

So the second copy gives me no trouble, but the one copying the client's reader to the proxy's writer does. Any ideas what might have gone wrong? All the remaining buffers should have been properly closed at that point right?

I've tried different proxies but they all give me the same issue. 

Thanks