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// Copyright 2018 Developers of the Rand project.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]
compile_error!("This crate is only for the `wasm32-unknown-unknown` target");
use wasm_bindgen::prelude::*;
use getrandom::{register_custom_getrandom, Error};
#[derive(Clone, Debug)]
Node(NodeCrypto),
Browser(BrowserCrypto),
}
// JsValues are always per-thread, so we initialize RngSource for each thread.
// See: https://github.com/rustwasm/wasm-bindgen/pull/955
thread_local!(
static RNG_SOURCE: RefCell<Option<RngSource>> = RefCell::new(None);
);
register_custom_getrandom!(getrandom_inner);
fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
RNG_SOURCE.with(|f| {
let mut source = f.borrow_mut();
if source.is_none() {
*source = Some(getrandom_init()?);
}
match source.as_ref().unwrap() {
RngSource::Node(n) => n.random_fill_sync(dest),
RngSource::Browser(n) => {
// see https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
//
// where it says:
//
// > A QuotaExceededError DOMException is thrown if the
// > requested length is greater than 65536 bytes.
for chunk in dest.chunks_mut(65536) {
n.get_random_values(chunk)
})
}
fn getrandom_init() -> Result<RngSource, Error> {
if let Ok(self_) = Global::get_self() {
// If `self` is defined then we're in a browser somehow (main window
// or web worker). We get `self.crypto` (called `msCrypto` on IE), so we
// can call `crypto.getRandomValues`. If `crypto` isn't defined, we
// assume we're in an older web browser and the OS RNG isn't available.
let crypto: BrowserCrypto = match (self_.crypto(), self_.ms_crypto()) {
(crypto, _) if !crypto.is_undefined() => crypto.into(),
(_, crypto) if !crypto.is_undefined() => crypto.into(),
_ => return Err(Error::BINDGEN_CRYPTO_UNDEF),
};
// Test if `crypto.getRandomValues` is undefined as well
if crypto.get_random_values_fn().is_undefined() {
return Err(Error::BINDGEN_GRV_UNDEF);
return Ok(RngSource::Node(MODULE.require("crypto")));
type Global;
#[wasm_bindgen(getter, catch, static_method_of = Global, js_class = self, js_name = self)]
fn get_self() -> Result<Self_, JsValue>;
type Self_;
#[wasm_bindgen(method, getter, js_name = "msCrypto", structural)]
fn ms_crypto(me: &Self_) -> JsValue;
#[derive(Clone, Debug)]
type BrowserCrypto;
// TODO: these `structural` annotations here ideally wouldn't be here to
// avoid a JS shim, but for now with feature detection they're
// unavoidable.
#[wasm_bindgen(method, js_name = getRandomValues, structural, getter)]
fn get_random_values_fn(me: &BrowserCrypto) -> JsValue;
#[wasm_bindgen(method, js_name = getRandomValues, structural)]
fn get_random_values(me: &BrowserCrypto, buf: &mut [u8]);
#[derive(Clone, Debug)]
type NodeCrypto;
#[wasm_bindgen(method, js_name = randomFillSync, structural)]
fn random_fill_sync(me: &NodeCrypto, buf: &mut [u8]);
type NodeModule;
#[wasm_bindgen(js_name = module)]
static MODULE: NodeModule;
#[wasm_bindgen(method)]
fn require(this: &NodeModule, s: &str) -> NodeCrypto;