how can establish() and io() preserve more of lifetime and type for io argument?

[mcr]

I am trying to connect MbedTls to the ureq's newest TLSConnector.
My WIP (does not compile) is at:
https://github.com/AnimaGUS-minerva/ureq/tree/mbedtls-2/examples/mbedtls-req

I pass the desired tcp_stream into establish(), and return a Box that has the dyn ReadWrite trait:

impl TlsConnector for MbedTlsConnector {
    fn connect(
        &self,
        dns_name: &str,
        tcp_stream: TcpStream,
    ) -> Result<Box<dyn ReadWrite>, Error> {

        let ctx = self.context.lock().unwrap();

        match ctx.establish(tcp_stream, None) {

I need to implement a socket routine for this, returning the same tcp_stream as before, but the obvious method of calling context.io() isn't going to work, because it return dyn Any, and I think that I need a dyn ReadWrite.

impl ReadWrite for MbedTlsConnector {
    fn socket(&self) -> Option<&TcpStream> {
        let ctx = self.context.lock().unwrap();
        Some(&(ctx.io() as TcpStream))
    }
}

Looking for advice here. Maybe the wrapper establish()/io() should change?
Or what?

[mcr]

My question remains... I don't know how to get the socket back out, and I think that maybe it is impossible.
ureq would like it so that it can do connection caching. For now, I am just turning that off.
See: algesten/ureq#469

[jethrogb]

This may be fixed in #182?