Panic when verifying malformed signed cookie

[5225225]

reproduction:

fn main() {
    let data = "x=yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy£";

    let c = cookie::Cookie::parse(data).expect("failed to parse cookie");

    let key = cookie::Key::from(&[0u8; 64]);

    let mut jar = cookie::CookieJar::new();

    let signed = jar.signed_mut(&key);

    signed.verify(c).expect("failed to verify cookie");
}

stack trace:

thread 'main' panicked at 'byte index 44 is not a char boundary; it is inside '£' (bytes 43..45) of `yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy£`', /rustc/952fdf2a1119affa1b37bcacb0c49cf9f0168ac8/library/core/src/str/mod.rs:576:13
stack backtrace:
   0: rust_begin_unwind
             at /rustc/952fdf2a1119affa1b37bcacb0c49cf9f0168ac8/library/std/src/panicking.rs:515:5
   1: core::panicking::panic_fmt
             at /rustc/952fdf2a1119affa1b37bcacb0c49cf9f0168ac8/library/core/src/panicking.rs:92:14
   2: core::str::slice_error_fail
   3: core::str::<impl str>::split_at
             at /rustc/952fdf2a1119affa1b37bcacb0c49cf9f0168ac8/library/core/src/str/mod.rs:576:13
   4: cookie::secure::signed::SignedJar<J>::_verify
             at /home/jess/.cargo/git/checkouts/cookie-rs-9c795d75da5c954b/0de451d/src/secure/signed.rs:57:35
   5: cookie::secure::signed::SignedJar<J>::verify
             at /home/jess/.cargo/git/checkouts/cookie-rs-9c795d75da5c954b/0de451d/src/secure/signed.rs:94:28
   6: scratchQVE5xNE9W::main
             at ./src/main.rs:12:5
   7: core::ops::function::FnOnce::call_once
             at /rustc/952fdf2a1119affa1b37bcacb0c49cf9f0168ac8/library/core/src/ops/function.rs:227:5

Tested on 0de451d as well as 0.15.0 from crates.io

[SergioBenitez]

Turns out split_at for a string and split_at for a Vec panic for different reasons. Bummer. Pushing a fix immediately.

[SergioBenitez]

Published in 0.15.1.