Can't create or modify hyper::client::connect::Destination

[kpcyrd]

I'm trying to write a connector that takes a destination, modifies it and passes it to the next connector. It seems this is currently not possible because there's no way to get a mutable reference to the internal state and only hyper can create new Destination objects.

My usecase is having a custom dns resolver as a Connector that resolves the domain before passing it to the final HttpConnector that creates the connection.

[seanmonstar]

I definitely get the use case! I'd like to find a way to support it, but I'd also like to list why the constructor was so far private:

• The Destination type may gain more fields, such as in Add ALPN/HTTP2 support to Connect #1485 to support ALPN.
• I worried that if a Destination gained more fields in new release, and a connector didn't know that and could create their own, then it could be possible for some intent on the connect action could be silently lost.

What if, without adding a constructor, you could just mutate the internal URI of the Destination?

[kpcyrd]

that would work for me as well

[sfackler]

This would be nice for me as well. In hyper 0.11, I had a "stack" of composed connectors: HttpsConnector<ProxyConnector<HttpConnector>>. The ProxyConnector handled CONNECT tunneling for HTTPS proxies, and so needs to tell the underlying connector to point to the proxy address. In 0.12, that isn't currently possible so I ended up using a non-connector type under the ProxyConnector that just took a host/port.