Recovering the pull request done by @staticglobal in #237 , it does what was doing but refactoring code to be used in v2 .

Quoting original contribution:

As documented here: https://xdebug.org/docs-dbgp.php#just-in-time-debugging-and-debugger-proxies

Defines two new config parameters:

* proxy_host (default '')

* proxy_port (default 9001)

If both options are non-empty, the Connection class does a few new things at the beginning and end of our session.

New workflow when using a proxy is:

* VIM listens for debugger connections on local IP and port X (default=9000) like always

* VIM makes a connection to the proxy server on port Y (default=9001)

* VIM sends a "proxyinit" command, which includes ide_key and the port we are listening on (X)

* Proxy registers our IP/port with our ide_key and sends an XML response

* VIM processes the XML response and disconnects

* VIM starts the usual 20s wait for debugger connection

* debuggers are all hard-coded to connect to the proxy for debugging sessions

* If a debugger connection comes into the proxy (before the VIM timeout) with our ide_key, the proxy will connect back to us on port X and copy all data back and forth between VIM and debugger.  This connection is indistinguishable from a regular debugger connection (except originating from the proxy IP instead of the remote host IP).

* When we are done, VIM makes another connection to proxy port Y and sends a "proxystop" command to un-map our ide_key