1 files changed, 114 insertions, 0 deletions
diff --git a/getrandom/src/wasm32_stdweb.rs b/getrandom/src/wasm32_stdweb.rs
new file mode 100644
index 0000000..6e5e78a
--- /dev/null
+++ b/getrandom/src/wasm32_stdweb.rs
@@ -0,0 +1,114 @@
+// 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 stdweb
+extern crate std;
+
+use core::mem;
+
+use stdweb::js;
+use stdweb::unstable::TryInto;
+use stdweb::web::error::Error as WebError;
+
+use crate::error::{STDWEB_NO_RNG, STDWEB_RNG_FAILED};
+use crate::Error;
+use std::sync::Once;
+
+#[derive(Clone, Copy, Debug)]
+enum RngSource {
+    Browser,
+    Node,
+}
+
+pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
+    assert_eq!(mem::size_of::<usize>(), 4);
+    static ONCE: Once = Once::new();
+    static mut RNG_SOURCE: Result<RngSource, Error> = Ok(RngSource::Node);
+
+    // SAFETY: RNG_SOURCE is only written once, before being read.
+    ONCE.call_once(|| unsafe {
+        RNG_SOURCE = getrandom_init();
+    });
+    getrandom_fill(unsafe { RNG_SOURCE }?, dest)
+}
+
+fn getrandom_init() -> Result<RngSource, Error> {
+    let result = js! {
+        try {
+            if (
+                typeof self === "object" &&
+                typeof self.crypto === "object" &&
+                typeof self.crypto.getRandomValues === "function"
+            ) {
+                return { success: true, ty: 1 };
+            }
+
+            if (typeof require("crypto").randomBytes === "function") {
+                return { success: true, ty: 2 };
+            }
+
+            return { success: false, error: new Error("not supported") };
+        } catch(err) {
+            return { success: false, error: err };
+        }
+    };
+
+    if js! { return @{ result.as_ref() }.success } == true {
+        let ty = js! { return @{ result }.ty };
+
+        if ty == 1 {
+            Ok(RngSource::Browser)
+        } else if ty == 2 {
+            Ok(RngSource::Node)
+        } else {
+            unreachable!()
+        }
+    } else {
+        let _err: WebError = js! { return @{ result }.error }.try_into().unwrap();
+        error!("getrandom unavailable: {}", _err);
+        Err(STDWEB_NO_RNG)
+    }
+}
+
+fn getrandom_fill(source: RngSource, dest: &mut [u8]) -> Result<(), Error> {
+    for chunk in dest.chunks_mut(65536) {
+        let len = chunk.len() as u32;
+        let ptr = chunk.as_mut_ptr() as i32;
+
+        let result = match source {
+            RngSource::Browser => js! {
+                try {
+                    let array = new Uint8Array(@{ len });
+                    self.crypto.getRandomValues(array);
+                    HEAPU8.set(array, @{ ptr });
+
+                    return { success: true };
+                } catch(err) {
+                    return { success: false, error: err };
+                }
+            },
+            RngSource::Node => js! {
+                try {
+                    let bytes = require("crypto").randomBytes(@{ len });
+                    HEAPU8.set(new Uint8Array(bytes), @{ ptr });
+
+                    return { success: true };
+                } catch(err) {
+                    return { success: false, error: err };
+                }
+            },
+        };
+
+        if js! { return @{ result.as_ref() }.success } != true {
+            let _err: WebError = js! { return @{ result }.error }.try_into().unwrap();
+            error!("getrandom failed: {}", _err);
+            return Err(STDWEB_RNG_FAILED);
+        }
+    }
+    Ok(())
+}