Implement window.crypto.getRandomValues()

components/script/dom/crypto.rs

@@ -0,0 +1,82 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CryptoBinding;
+use dom::bindings::codegen::Bindings::CryptoBinding::CryptoMethods;
+use dom::bindings::error::{Error, Fallible};
+use dom::bindings::global::GlobalRef;
+use dom::bindings::js::Root;
+use dom::bindings::utils::{Reflector, reflect_dom_object};
+use dom::bindings::cell::DOMRefCell;
+
+use js::jsapi::{JSContext, JSObject};
+use js::jsapi::{JS_GetObjectAsArrayBufferView, JS_GetArrayBufferViewType, Type};
+
+use std::ptr;
+use std::slice;
+
+use rand::{Rng, OsRng};
+
+no_jsmanaged_fields!(OsRng);
+
+// https://developer.mozilla.org/en-US/docs/Web/API/Crypto
+#[dom_struct]
+pub struct Crypto {
+    reflector_: Reflector,
+    rng: DOMRefCell<OsRng>,
+}
+
+impl Crypto {
+    fn new_inherited() -> Crypto {
+        Crypto {
+            reflector_: Reflector::new(),
+            rng: DOMRefCell::new(OsRng::new().unwrap()),
+        }
+    }
+
+    pub fn new(global: GlobalRef) -> Root<Crypto> {
+        reflect_dom_object(box Crypto::new_inherited(), global, CryptoBinding::Wrap)
+    }
+}
+
+impl<'a> CryptoMethods for &'a Crypto {
+    // https://dvcs.w3.org/hg/webcrypto-api/raw-file/tip/spec/Overview.html#Crypto-method-getRandomValues
+    #[allow(unsafe_code)]
+    fn GetRandomValues(self, _cx: *mut JSContext, input: *mut JSObject)
+                       -> Fallible<*mut JSObject> {
+        let mut length = 0;
+        let mut data = ptr::null_mut();
+        if unsafe { JS_GetObjectAsArrayBufferView(input, &mut length, &mut data).is_null() } {
+            return Err(Error::Type("Argument to Crypto.getRandomValues is not an ArrayBufferView".to_owned()));
+        }
+        if !is_integer_buffer(input) {
+            return Err(Error::TypeMismatch);
+        }
+        if length > 65536 {
+            return Err(Error::QuotaExceeded);
+        }
+
+        let mut buffer = unsafe {
+            slice::from_raw_parts_mut(data, length as usize)
+        };
+
+        self.rng.borrow_mut().fill_bytes(&mut buffer);
+
+        Ok(input)
+    }
+}
+
+#[allow(unsafe_code)]
+fn is_integer_buffer(input: *mut JSObject) -> bool {
+    match unsafe { JS_GetArrayBufferViewType(input) } {
+        Type::Uint8 |
+        Type::Uint8Clamped |
+        Type::Int8 |
+        Type::Uint16 |
+        Type::Int16 |
+        Type::Uint32 |
+        Type::Int32 => true,
+        _ => false
+    }
+}