vendor in rng for wasm, upgrade getrandom and rand to latest

Cargo.toml

@@ -68,7 +68,7 @@ v6 = ["atomic"]
 v7 = ["rng"]
 v8 = []
 
-js = ["dep:wasm-bindgen", "getrandom?/js"]
+js = ["dep:wasm-bindgen"]
 
 rng = ["dep:getrandom"]
 fast-rng = ["rng", "dep:rand"]
@@ -123,17 +123,16 @@ optional = true
 version = "1"
 default-features = false
 
-# Public
-# Usage of `getrandom`'s pluggable randomness for custom targets is documented
-# in `uuid`'s library docs
-[dependencies.getrandom]
+# Private
+# (Formally public)
+[target.'cfg(not(all(target_arch = "wasm32", target_vendor = "unknown", target_os = "unknown")))'.dependencies.getrandom]
 optional = true
-version = "0.2"
+version = "0.3"
 
 # Private
-[dependencies.rand]
+[target.'cfg(not(all(target_arch = "wasm32", target_vendor = "unknown", target_os = "unknown")))'.dependencies.rand]
 optional = true
-version = "0.8"
+version = "0.9"
 
 # Private
 [dependencies.md-5]

src/lib.rs

@@ -163,11 +163,13 @@
 //! * `serde`.
 //!
 //! If you need to use `v4` or `v7` in a no-std environment, you'll need to
-//! follow [`getrandom`'s docs] on configuring a source of randomness
-//! on currently unsupported targets. Alternatively, you can produce
-//! random bytes yourself and then pass them to [`Builder::from_random_bytes`]
+//! produce random bytes yourself and then pass them to [`Builder::from_random_bytes`]
 //! without enabling the `v4` or `v7` features.
 //!
+//! Versions of `uuid` `1.12` or earlier relied on `getrandom` for randomness, this
+//! is no longer guaranteed and configuring `getrandom`'s provider is not guaranteed
+//! to make other features relying on randomness work.
+//!
 //! # Examples
 //!
 //! Parse a UUID given in the simple format and print it as a URN:
@@ -202,8 +204,6 @@
 //! * [RFC 9562: Universally Unique IDentifiers (UUID)](https://www.ietf.org/rfc/rfc9562.html).
 //!
 //! [`wasm-bindgen`]: https://crates.io/crates/wasm-bindgen
-//! [`cargo-web`]: https://crates.io/crates/cargo-web
-//! [`getrandom`'s docs]: https://docs.rs/getrandom
 
 #![no_std]
 #![deny(missing_debug_implementations, missing_docs)]

src/rng.rs

@@ -1,59 +1,203 @@
-#[cfg(any(feature = "v4", feature = "v7"))]
-pub(crate) fn u128() -> u128 {
-    #[cfg(not(feature = "fast-rng"))]
-    {
-        let mut bytes = [0u8; 16];
+#[cfg(not(all(target_arch = "wasm32", target_vendor = "unknown", target_os = "unknown")))]
+mod imp {
+    #[cfg(any(feature = "v4", feature = "v7"))]
+    pub(crate) fn u128() -> u128 {
+        #[cfg(not(feature = "fast-rng"))]
+        {
+            let mut bytes = [0u8; 16];
 
-        getrandom::getrandom(&mut bytes).unwrap_or_else(|err| {
-            // NB: getrandom::Error has no source; this is adequate display
-            panic!("could not retrieve random bytes for uuid: {}", err)
-        });
+            getrandom::fill(&mut bytes).unwrap_or_else(|err| {
+                // NB: getrandom::Error has no source; this is adequate display
+                panic!("could not retrieve random bytes for uuid: {}", err)
+            });
 
-        u128::from_ne_bytes(bytes)
+            u128::from_ne_bytes(bytes)
+        }
+
+        #[cfg(feature = "fast-rng")]
+        {
+            rand::random()
+        }
     }
 
-    #[cfg(feature = "fast-rng")]
-    {
-        rand::random()
+    #[cfg(any(feature = "v1", feature = "v6"))]
+    pub(crate) fn u16() -> u16 {
+        #[cfg(not(feature = "fast-rng"))]
+        {
+            let mut bytes = [0u8; 2];
+
+            getrandom::fill(&mut bytes).unwrap_or_else(|err| {
+                // NB: getrandom::Error has no source; this is adequate display
+                panic!("could not retrieve random bytes for uuid: {}", err)
+            });
+
+            u16::from_ne_bytes(bytes)
+        }
+
+        #[cfg(feature = "fast-rng")]
+        {
+            rand::random()
+        }
+    }
+
+    #[cfg(feature = "v7")]
+    pub(crate) fn u64() -> u64 {
+        #[cfg(not(feature = "fast-rng"))]
+        {
+            let mut bytes = [0u8; 8];
+
+            getrandom::fill(&mut bytes).unwrap_or_else(|err| {
+                // NB: getrandom::Error has no source; this is adequate display
+                panic!("could not retrieve random bytes for uuid: {}", err)
+            });
+
+            u64::from_ne_bytes(bytes)
+        }
+
+        #[cfg(feature = "fast-rng")]
+        {
+            rand::random()
+        }
     }
 }
 
-#[cfg(any(feature = "v1", feature = "v6"))]
-pub(crate) fn u16() -> u16 {
-    #[cfg(not(feature = "fast-rng"))]
-    {
-        let mut bytes = [0u8; 2];
+#[cfg(all(feature = "js", target_arch = "wasm32", target_vendor = "unknown", target_os = "unknown"))]
+mod imp {
+    /*
+    This module preserves the stabilized behavior of `uuid` that requires the
+    `js` feature to enable rng on `wasm32-unknown-unknown`, which it inherited
+    from `getrandom` `0.2`
+    */
 
-        getrandom::getrandom(&mut bytes).unwrap_or_else(|err| {
-            // NB: getrandom::Error has no source; this is adequate display
-            panic!("could not retrieve random bytes for uuid: {}", err)
-        });
+    #[cfg(any(feature = "v4", feature = "v7"))]
+    pub(crate) fn u128() -> u128 {
+        let mut bytes = [0u8; 16];
 
-        u16::from_ne_bytes(bytes)
+        if !getrandom::fill(&mut bytes) {
+            panic!("could not retrieve random bytes for uuid")
+        }
+
+        u128::from_ne_bytes(bytes)
     }
 
-    #[cfg(feature = "fast-rng")]
-    {
-        rand::random()
+    #[cfg(any(feature = "v1", feature = "v6"))]
+    pub(crate) fn u16() -> u16 {
+        let mut bytes = [0u8; 2];
+
+        if !getrandom::fill(&mut bytes) {
+            panic!("could not retrieve random bytes for uuid")
+        }
+
+        u16::from_ne_bytes(bytes)
     }
-}
 
-#[cfg(feature = "v7")]
-pub(crate) fn u64() -> u64 {
-    #[cfg(not(feature = "fast-rng"))]
-    {
+    #[cfg(feature = "v7")]
+    pub(crate) fn u64() -> u64 {
         let mut bytes = [0u8; 8];
 
-        getrandom::getrandom(&mut bytes).unwrap_or_else(|err| {
-            // NB: getrandom::Error has no source; this is adequate display
-            panic!("could not retrieve random bytes for uuid: {}", err)
-        });
+        if !getrandom::fill(&mut bytes) {
+            panic!("could not retrieve random bytes for uuid")
+        }
 
         u64::from_ne_bytes(bytes)
     }
 
-    #[cfg(feature = "fast-rng")]
-    {
-        rand::random()
+    mod getrandom {
+        /*
+        Vendored from `getrandom`: https://github.com/rust-random/getrandom/blob/ce3b017fdee0233c6ecd61e68b96a84bf6f911bf/src/backends/wasm_js.rs
+
+        Copyright (c) 2018-2024 The rust-random Project Developers
+        Copyright (c) 2014 The Rust Project Developers
+
+        Permission is hereby granted, free of charge, to any
+        person obtaining a copy of this software and associated
+        documentation files (the "Software"), to deal in the
+        Software without restriction, including without
+        limitation the rights to use, copy, modify, merge,
+        publish, distribute, sublicense, and/or sell copies of
+        the Software, and to permit persons to whom the Software
+        is furnished to do so, subject to the following
+        conditions:
+
+        The above copyright notice and this permission notice
+        shall be included in all copies or substantial portions
+        of the Software.
+
+        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+        ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+        TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+        PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+        SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+        CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+        OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+        IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+        DEALINGS IN THE SOFTWARE.
+        */
+
+        use wasm_bindgen::{prelude::wasm_bindgen, JsValue};
+
+        // Maximum buffer size allowed in `Crypto.getRandomValuesSize` is 65536 bytes.
+        // See https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
+        const MAX_BUFFER_SIZE: usize = 65536;
+
+        #[cfg(not(target_feature = "atomics"))]
+        #[inline]
+        pub fn fill(dest: &mut [u8]) -> bool {
+            for chunk in dest.chunks_mut(MAX_BUFFER_SIZE) {
+                if get_random_values(chunk).is_err() {
+                    return false;
+                }
+            }
+
+            true
+        }
+
+        #[cfg(target_feature = "atomics")]
+        pub fn fill(dest: &mut [u8]) -> bool {
+            // getRandomValues does not work with all types of WASM memory,
+            // so we initially write to browser memory to avoid exceptions.
+            let buf_len = usize::min(dest.len(), MAX_BUFFER_SIZE);
+            let buf_len_u32 = buf_len
+                .try_into()
+                .expect("buffer length is bounded by MAX_BUFFER_SIZE");
+            let buf = js_sys::Uint8Array::new_with_length(buf_len_u32);
+            for chunk in dest.chunks_mut(buf_len) {
+                let chunk_len = chunk
+                    .len()
+                    .try_into()
+                    .expect("chunk length is bounded by MAX_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 = if chunk_len == buf_len_u32 {
+                    &buf
+                } else {
+                    &buf.subarray(0, chunk_len)
+                };
+
+                if get_random_values(sub_buf).is_err() {
+                    return false;
+                }
+
+                sub_buf.copy_to_uninit(chunk);
+            }
+
+            true
+        }
+
+        #[wasm_bindgen]
+        extern "C" {
+            // Crypto.getRandomValues()
+            #[cfg(not(target_feature = "atomics"))]
+            #[wasm_bindgen(js_namespace = ["globalThis", "crypto"], js_name = getRandomValues, catch)]
+            fn get_random_values(buf: &mut [u8]) -> Result<(), JsValue>;
+            #[cfg(target_feature = "atomics")]
+            #[wasm_bindgen(js_namespace = ["globalThis", "crypto"], js_name = getRandomValues, catch)]
+            fn get_random_values(buf: &js_sys::Uint8Array) -> Result<(), JsValue>;
+        }
     }
 }
+
+#[cfg(all(not(feature = "js"), target_arch = "wasm32", target_vendor = "unknown", target_os = "unknown"))]
+compile_error!("the `js` feature is required for the `wasm32-unknown-unknown` target");
+
+pub(crate) use self::imp::*;