vendor/getrandom-0.1.14/src/wasm32_stdweb.rs

   1 // Copyright 2018 Developers of the Rand project.
   2 //
   3 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   4 // https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   5 // <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
   6 // option. This file may not be copied, modified, or distributed
   7 // except according to those terms.
   8
   9 //! Implementation for WASM via stdweb
  10 extern crate std;
  11
  12 use core::mem;
  13
  14 use stdweb::js;
  15 use stdweb::unstable::TryInto;
  16 use stdweb::web::error::Error as WebError;
  17
  18 use crate::error::{STDWEB_NO_RNG, STDWEB_RNG_FAILED};
  19 use crate::Error;
  20 use std::sync::Once;
  21
  22 #[derive(Clone, Copy, Debug)]
  23 enum RngSource {
  24     Browser,
  25     Node,
  26 }
  27
  28 pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
  29     assert_eq!(mem::size_of::<usize>(), 4);
  30     static ONCE: Once = Once::new();
  31     static mut RNG_SOURCE: Result<RngSource, Error> = Ok(RngSource::Node);
  32
  33     // SAFETY: RNG_SOURCE is only written once, before being read.
  34     ONCE.call_once(|| unsafe {
  35         RNG_SOURCE = getrandom_init();
  36     });
  37     getrandom_fill(unsafe { RNG_SOURCE }?, dest)
  38 }
  39
  40 fn getrandom_init() -> Result<RngSource, Error> {
  41     let result = js! {
  42         try {
  43             if (
  44                 typeof self === "object" &&
  45                 typeof self.crypto === "object" &&
  46                 typeof self.crypto.getRandomValues === "function"
  47             ) {
  48                 return { success: true, ty: 1 };
  49             }
  50
  51             if (typeof require("crypto").randomBytes === "function") {
  52                 return { success: true, ty: 2 };
  53             }
  54
  55             return { success: false, error: new Error("not supported") };
  56         } catch(err) {
  57             return { success: false, error: err };
  58         }
  59     };
  60
  61     if js! { return @{ result.as_ref() }.success } == true {
  62         let ty = js! { return @{ result }.ty };
  63
  64         if ty == 1 {
  65             Ok(RngSource::Browser)
  66         } else if ty == 2 {
  67             Ok(RngSource::Node)
  68         } else {
  69             unreachable!()
  70         }
  71     } else {
  72         let _err: WebError = js! { return @{ result }.error }.try_into().unwrap();
  73         error!("getrandom unavailable: {}", _err);
  74         Err(STDWEB_NO_RNG)
  75     }
  76 }
  77
  78 fn getrandom_fill(source: RngSource, dest: &mut [u8]) -> Result<(), Error> {
  79     for chunk in dest.chunks_mut(65536) {
  80         let len = chunk.len() as u32;
  81         let ptr = chunk.as_mut_ptr() as i32;
  82
  83         let result = match source {
  84             RngSource::Browser => js! {
  85                 try {
  86                     let array = new Uint8Array(@{ len });
  87                     self.crypto.getRandomValues(array);
  88                     HEAPU8.set(array, @{ ptr });
  89
  90                     return { success: true };
  91                 } catch(err) {
  92                     return { success: false, error: err };
  93                 }
  94             },
  95             RngSource::Node => js! {
  96                 try {
  97                     let bytes = require("crypto").randomBytes(@{ len });
  98                     HEAPU8.set(new Uint8Array(bytes), @{ ptr });
  99
 100                     return { success: true };
 101                 } catch(err) {
 102                     return { success: false, error: err };
 103                 }
 104             },
 105         };
 106
 107         if js! { return @{ result.as_ref() }.success } != true {
 108             let _err: WebError = js! { return @{ result }.error }.try_into().unwrap();
 109             error!("getrandom failed: {}", _err);
 110             return Err(STDWEB_RNG_FAILED);
 111         }
 112     }
 113     Ok(())
 114 }