1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
|
// 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.
use crate::Error;
extern crate std;
use std::thread_local;
use js_sys::Uint8Array;
use wasm_bindgen::{prelude::*, JsCast};
// Maximum is 65536 bytes see https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
const BROWSER_CRYPTO_BUFFER_SIZE: usize = 256;
enum RngSource {
Node(NodeCrypto),
Browser(BrowserCrypto, Uint8Array),
}
// 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: Result<RngSource, Error> = getrandom_init();
);
pub(crate) fn getrandom_inner(dest: &mut [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);
}
}
RngSource::Browser(crypto, buf) => {
// getRandomValues does not work with all types of WASM memory,
// so we initially write to browser memory to avoid exceptions.
for chunk in dest.chunks_mut(BROWSER_CRYPTO_BUFFER_SIZE) {
// The chunk can be smaller than buf's length, so we call to
// JS to create a smaller view of buf without allocation.
let sub_buf = buf.subarray(0, chunk.len() as u32);
if crypto.get_random_values(&sub_buf).is_err() {
return Err(Error::WEB_GET_RANDOM_VALUES);
}
sub_buf.copy_to(chunk);
}
}
};
Ok(())
})
}
fn getrandom_init() -> Result<RngSource, Error> {
let global: Global = js_sys::global().unchecked_into();
if is_node(&global) {
let crypto = require("crypto").map_err(|_| Error::NODE_CRYPTO)?;
return Ok(RngSource::Node(crypto));
}
// Assume we are in some Web environment (browser or web worker). We get
// `self.crypto` (called `msCrypto` on IE), so we can call
// `crypto.getRandomValues`. If `crypto` isn't defined, we assume that
// we are in an older web browser and the OS RNG isn't available.
let crypto = match (global.crypto(), global.ms_crypto()) {
(c, _) if c.is_object() => c,
(_, c) if c.is_object() => c,
_ => return Err(Error::WEB_CRYPTO),
};
let buf = Uint8Array::new_with_length(BROWSER_CRYPTO_BUFFER_SIZE as u32);
Ok(RngSource::Browser(crypto, buf))
}
// Taken from https://www.npmjs.com/package/browser-or-node
fn is_node(global: &Global) -> bool {
let process = global.process();
if process.is_object() {
let versions = process.versions();
if versions.is_object() {
return versions.node().is_string();
}
}
false
}
#[wasm_bindgen]
extern "C" {
type Global; // Return type of js_sys::global()
// Web Crypto API (https://www.w3.org/TR/WebCryptoAPI/)
#[wasm_bindgen(method, getter, js_name = "msCrypto")]
fn ms_crypto(this: &Global) -> BrowserCrypto;
#[wasm_bindgen(method, getter)]
fn crypto(this: &Global) -> BrowserCrypto;
type BrowserCrypto;
#[wasm_bindgen(method, js_name = getRandomValues, catch)]
fn get_random_values(this: &BrowserCrypto, buf: &Uint8Array) -> Result<(), JsValue>;
// Node JS crypto module (https://nodejs.org/api/crypto.html)
#[wasm_bindgen(catch, js_name = "module.require")]
fn require(s: &str) -> Result<NodeCrypto, JsValue>;
type NodeCrypto;
#[wasm_bindgen(method, js_name = randomFillSync, catch)]
fn random_fill_sync(this: &NodeCrypto, buf: &mut [u8]) -> Result<(), JsValue>;
// Node JS process Object (https://nodejs.org/api/process.html)
#[wasm_bindgen(method, getter)]
fn process(this: &Global) -> Process;
type Process;
#[wasm_bindgen(method, getter)]
fn versions(this: &Process) -> Versions;
type Versions;
#[wasm_bindgen(method, getter)]
fn node(this: &Versions) -> JsValue;
}
|
