HTTPS/TLS support

[nappa85]

I know it's not an issue directly connected to multipart, but it's chain's closing ring...

I need to send a multipart/form-data submit to an https address, I searched for a working example without luck, so I tried to merge different examples from hyper_native_tls and multipart.
I haven't beed able to find a method to specify a call method (GET, POST, PUT, ecc...).

You can find my code here: https://github.com/nappa85/Rustegram/blob/master/client_lib/src/lib.rs
The test is everything you need to make it work, or fail, because it fails with
thread 'tests::it_works' panicked at 'Error sending multipart request: Io(Error { repr: Custom(Custom { kind: WriteZero, error: StringError("failed to write whole buffer") }) })', src/libcore/result.rs:906:4

Maybe my code could be helpful to create a working example about multipart over HTTPS

[abonander]

Multipart is done exclusively with the POST verb. This is handled in Multipart::client_request(). As far as I can tell, your usage is correct; the error is coming from a write() call that returns zero bytes written from a non-empty buffer (I assume it's a non-empty buffer, if not that's a bug in Multipart).

[abonander]

Okay, I've run your test and gotten the error but there's something I don't understand. The only occurrence of that error string is src/server/save.rs which is the wrong side of the API. I'm not sure what's going on here.

[abonander]

Ah, I see, it also occurs in the Write impl for &mut [u8]. It's when the slice is smaller than the input data, which is... not optimal.

[abonander]

I stepped through this with a debugger and it doesn't seem to be Multipart's fault. The error occurs when trying to write to the network stream, after io::copy() has read all of PreparedFields's data to a buffer on the stack. This may be an issue with hyper-native-tls, I don't know.

[nappa85]

Thank you very much for your support.
I've tried every version of hyper-native-tls released so far and the problem doesn't change, I'll look deeper into it asap, in the meanwhile I started looking into your multipart-async, maybe I can help you on it.