Given connection to communicate with a proxy (eg, a #GSocketConnection that is connected to the proxy server), this does the necessary handshake to connect to proxy_address, and if required, wraps the #GIOStream to handle proxy payload.
Asynchronous version of gio.proxy.Proxy.connect.
Some proxy protocols expect to be passed a hostname, which they will resolve to an IP address themselves. Others, like SOCKS4, do not allow this. This function will return false if proxy is implementing such a protocol. When false is returned, the caller should resolve the destination hostname first, and then pass a #GProxyAddress containing the stringified IP address to gio.proxy.Proxy.connect or gio.proxy.Proxy.connectAsync.
A gio.proxy.Proxy handles connecting to a remote host via a given type of proxy server. It is implemented by the gio-proxy extension point. The extensions are named after their proxy protocol name. As an example, a SOCKS5 proxy implementation can be retrieved with the name socks5 using the function gio.ioextension_point.IOExtensionPoint.getExtensionByName.