How to get the cookie from a GET response?

Question

I am writing a function that makes a GET request to a website and returns the response cookie:

extern crate futures;
extern crate hyper;
extern crate tokio_core;

use tokio_core::reactor::Core;
use hyper::Client;
use std::error::Error;
use hyper::header::Cookie;
use futures::future::Future;

fn get_new_cookie() -> Result<String, Box<Error>> {
    println!("Getting cookie...");
    let core = Core::new()?;
    let client = Client::new(&core.handle());
    println!("Created client");

    let uri = "http://www.cnn.com".parse().expect("Cannot parse url");
    println!("Parsed url");
    let response = client.get(uri).wait().expect("Cannot get url.");
    println!("Got response");
    let cookie = response
        .headers()
        .get::<Cookie>()
        .expect("Cannot get cookie");
    println!("Cookie: {}", cookie);

    Ok(cookie)
}

fn main() {
    println!("{:?}", get_new_cookie());
}

This doesn't work; it is stuck on the client.get(...) string. The output I'm getting is:

Getting cookie...
Created client
Parsed url

and after that nothing happens.

What am I doing wrong and how I can change it so it'd work?

Answer 1

As Stefan points out, by calling wait, you are putting the thread to sleep until the future has completed. However, that thread needs to run the event loop, so you've just caused a deadlock. Using Core::run is more correct.

As Francis Gagné points out, the "Cookie" header is used to send a cookie to the server. SetCookie is used to send a cookie to the client. It also returns a vector of all the cookies together:

fn get_new_cookie() -> Result<String, Box<Error>> {
    println!("Getting cookie...");
    let mut core = Core::new()?;

    let client = Client::new(&core.handle());
    println!("Created client");

    let uri = "http://www.cnn.com".parse().expect("Cannot parse url");
    println!("Parsed url");

    let response = core.run(client.get(uri)).expect("Cannot get url.");
    println!("Got response");

    let cookie = response
        .headers()
        .get::<SetCookie>()
        .expect("Cannot get cookie");
    println!("Cookie: {:?}", cookie);

    Ok(cookie.join(","))
}

---

However, if you only want a synchronous API, use Reqwest instead. It is built on top of Hyper:

extern crate reqwest;

use std::error::Error;
use reqwest::header::SetCookie;

fn get_new_cookie() -> Result<String, Box<Error>> {
    let response = reqwest::get("http://www.cnn.com")?;

    let cookies = match response.headers().get::<SetCookie>() {
        Some(cookies) => cookies.join(","),
        None => String::new(),
    };

    Ok(cookies)
}

fn main() {
    println!("{:?}", get_new_cookie());
}