| // 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 via wasm-bindgen |
| |
| use rand_core::{Error, ErrorKind}; |
| use super::OsRngImpl; |
| use super::__wbg_shims::*; |
| |
| use wasm_bindgen::prelude::*; |
| |
| |
| #[derive(Clone, Debug)] |
| pub enum OsRng { |
| Node(NodeCrypto), |
| Browser(BrowserCrypto), |
| } |
| |
| impl OsRngImpl for OsRng { |
| fn new() -> Result<OsRng, Error> { |
| // First up we need to detect if we're running in node.js or a |
| // browser. To do this we get ahold of the `this` object (in a bit |
| // of a roundabout fashion). |
| // |
| // Once we have `this` we look at its `self` property, which is |
| // only defined on the web (either a main window or web worker). |
| let this = Function::new("return this").call(&JsValue::undefined()); |
| assert!(this != JsValue::undefined()); |
| let this = This::from(this); |
| let is_browser = this.self_() != JsValue::undefined(); |
| |
| if !is_browser { |
| return Ok(OsRng::Node(node_require("crypto"))) |
| } |
| |
| // If `self` is defined then we're in a browser somehow (main window |
| // or web worker). Here we want to try to use |
| // `crypto.getRandomValues`, but if `crypto` isn't defined we assume |
| // we're in an older web browser and the OS RNG isn't available. |
| let crypto = this.crypto(); |
| if crypto.is_undefined() { |
| let msg = "self.crypto is undefined"; |
| return Err(Error::new(ErrorKind::Unavailable, msg)) |
| } |
| |
| // Test if `crypto.getRandomValues` is undefined as well |
| let crypto: BrowserCrypto = crypto.into(); |
| if crypto.get_random_values_fn().is_undefined() { |
| let msg = "crypto.getRandomValues is undefined"; |
| return Err(Error::new(ErrorKind::Unavailable, msg)) |
| } |
| |
| // Ok! `self.crypto.getRandomValues` is a defined value, so let's |
| // assume we can do browser crypto. |
| Ok(OsRng::Browser(crypto)) |
| } |
| |
| fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { |
| match *self { |
| OsRng::Node(ref n) => n.random_fill_sync(dest), |
| OsRng::Browser(ref n) => n.get_random_values(dest), |
| } |
| Ok(()) |
| } |
| |
| fn max_chunk_size(&self) -> usize { |
| match *self { |
| OsRng::Node(_) => usize::max_value(), |
| OsRng::Browser(_) => { |
| // 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. |
| 65536 |
| } |
| } |
| } |
| |
| fn method_str(&self) -> &'static str { |
| match *self { |
| OsRng::Node(_) => "crypto.randomFillSync", |
| OsRng::Browser(_) => "crypto.getRandomValues", |
| } |
| } |
| } |