Created by: kaven276
- browser access https through forward proxy1
- proxy1 will accept connect request
- proxy1 will proxy to proxy2 by upgrade/websocket
- proxy1 will set headers[x-method-ori] to the original request method
- proxy2 may be deployed in cloud behind a reverse proxy
- the reverse proxy in cloud may only allow normal and websocket request
- and forbid connect request
- proxy2 is located in a free net env, it's not under network restriction
- proxy2 will connect to the target site, its https
- proxy2 will response with 101 switch protocol
- proxy2 will response with Connection Established next
- when proxy1 accept 101, it can not auto response with 101, but ignore it