support skipping cert validation for self-signed certificates

[xmclark]

Problem

If I run a web server with a self signed certificate, I can ignore self-signed certificate validation with --insecure/-k option of curl command e.g. curl -k https://localhost:3031.

Surf will return an error if I try to do this equivalent operation:

// async-std = { version = "1.1.0", features = ["attributes"] }
// surf = "1.0.3"

use surf;

#[async_std::main]
async fn main() {
    let url = "https://localhost:3031";
    let result = surf::get(url).await;
    println!("{:?}", result);
}

Error message printed: Err(SSLConnectFailed(None))

Reproduce

I can create a self signed key and certificate with openssl: openssl req -nodes -new -x509 -keyout server.key -out server.cert

I can then run a super basic web server (I made one with warp):

// tokio = " 0.2.0-alpha.6"
// warp = { git = "https://github.com/seanmonstar/warp.git", branch = "master", features = ["tls"] }

#[tokio::main]
async fn main() {
    use warp::Filter;

    // Match any request and return hello world!
    let routes = warp::get().map(|| "Hello, World!");

    warp::serve(routes)
        .tls("server.cert", "server.key")
        .run(([127, 0, 0, 1], 3031)).await;
}

Run the surf program above to test the server.

[yoshuawuyts]

I guess the solution for this would be to allow passing your own client, in which curl-specific options can be set. https://github.com/http-rs/surf/issues/69 and https://github.com/http-rs/surf/pull/66 would be the tracking issues for that.