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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::cell::RefCell;
use neqo_common::qerror;
use neqo_crypto::{hkdf, Aead, TLS_AES_128_GCM_SHA256, TLS_VERSION_1_3};
use crate::{version::Version, Error, Res};
/// The AEAD used for Retry is fixed, so use thread local storage.
fn make_aead(version: Version) -> Aead {
#[cfg(debug_assertions)]
::neqo_crypto::assert_initialized();
let secret = hkdf::import_key(TLS_VERSION_1_3, version.retry_secret()).unwrap();
Aead::new(
TLS_VERSION_1_3,
TLS_AES_128_GCM_SHA256,
&secret,
version.label_prefix(),
)
.unwrap()
}
thread_local!(static RETRY_AEAD_29: RefCell<Aead> = RefCell::new(make_aead(Version::Draft29)));
thread_local!(static RETRY_AEAD_V1: RefCell<Aead> = RefCell::new(make_aead(Version::Version1)));
thread_local!(static RETRY_AEAD_V2: RefCell<Aead> = RefCell::new(make_aead(Version::Version2)));
/// Run a function with the appropriate Retry AEAD.
pub fn use_aead<F, T>(version: Version, f: F) -> Res<T>
where
F: FnOnce(&Aead) -> Res<T>,
{
match version {
Version::Version2 => &RETRY_AEAD_V2,
Version::Version1 => &RETRY_AEAD_V1,
Version::Draft29 | Version::Draft30 | Version::Draft31 | Version::Draft32 => &RETRY_AEAD_29,
}
.try_with(|aead| f(&aead.borrow()))
.map_err(|e| {
qerror!("Unable to access Retry AEAD: {:?}", e);
Error::InternalError
})?
}
/// Determine how large the expansion is for a given key.
pub fn expansion(version: Version) -> usize {
use_aead(version, |aead| Ok(aead.expansion()))
.unwrap_or_else(|_| panic!("Unable to access Retry AEAD"))
}