diff options
Diffstat (limited to 'src/js.rs')
| -rw-r--r-- | src/js.rs | 37 |
1 files changed, 24 insertions, 13 deletions
@@ -1,14 +1,8 @@ -// 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. +//! Implementation for WASM based on Web and Node.js use crate::Error; extern crate std; -use std::thread_local; +use std::{mem::MaybeUninit, thread_local}; use js_sys::{global, Function, Uint8Array}; use wasm_bindgen::{prelude::wasm_bindgen, JsCast, JsValue}; @@ -16,6 +10,8 @@ use wasm_bindgen::{prelude::wasm_bindgen, JsCast, JsValue}; // Size of our temporary Uint8Array buffer used with WebCrypto methods // Maximum is 65536 bytes see https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues const WEB_CRYPTO_BUFFER_SIZE: usize = 256; +// Node.js's crypto.randomFillSync requires the size to be less than 2**31. +const NODE_MAX_BUFFER_SIZE: usize = (1 << 31) - 1; enum RngSource { Node(NodeCrypto), @@ -28,14 +24,27 @@ thread_local!( static RNG_SOURCE: Result<RngSource, Error> = getrandom_init(); ); -pub(crate) fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> { +pub(crate) fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> { RNG_SOURCE.with(|result| { let source = result.as_ref().map_err(|&e| e)?; match source { RngSource::Node(n) => { - if n.random_fill_sync(dest).is_err() { - return Err(Error::NODE_RANDOM_FILL_SYNC); + for chunk in dest.chunks_mut(NODE_MAX_BUFFER_SIZE) { + // SAFETY: chunk is never used directly, the memory is only + // modified via the Uint8Array view, which is passed + // directly to JavaScript. Also, crypto.randomFillSync does + // not resize the buffer. We know the length is less than + // u32::MAX because of the chunking above. + // Note that this uses the fact that JavaScript doesn't + // have a notion of "uninitialized memory", this is purely + // a Rust/C/C++ concept. + let res = n.random_fill_sync(unsafe { + Uint8Array::view_mut_raw(chunk.as_mut_ptr() as *mut u8, chunk.len()) + }); + if res.is_err() { + return Err(Error::NODE_RANDOM_FILL_SYNC); + } } } RngSource::Web(crypto, buf) => { @@ -49,7 +58,9 @@ pub(crate) fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> { if crypto.get_random_values(&sub_buf).is_err() { return Err(Error::WEB_GET_RANDOM_VALUES); } - sub_buf.copy_to(chunk); + + // SAFETY: `sub_buf`'s length is the same length as `chunk` + unsafe { sub_buf.raw_copy_to_ptr(chunk.as_mut_ptr() as *mut u8) }; } } }; @@ -120,7 +131,7 @@ extern "C" { type NodeCrypto; // crypto.randomFillSync() #[wasm_bindgen(method, js_name = randomFillSync, catch)] - fn random_fill_sync(this: &NodeCrypto, buf: &mut [u8]) -> Result<(), JsValue>; + fn random_fill_sync(this: &NodeCrypto, buf: Uint8Array) -> Result<(), JsValue>; // Ideally, we would just use `fn require(s: &str)` here. However, doing // this causes a Webpack warning. So we instead return the function itself |