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| </pre><pre class="rust"><code><span class="comment">// Copyright 2019 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. |
| |
| </span><span class="doccomment">//! Interface to the operating system's random number generator. |
| //! |
| //! # Supported targets |
| //! |
| //! | Target | Target Triple | Implementation |
| //! | ----------------- | ------------------ | -------------- |
| //! | Linux, Android | `*‑linux‑*` | [`getrandom`][1] system call if available, otherwise [`/dev/urandom`][2] after successfully polling `/dev/random` |
| //! | Windows | `*‑windows‑*` | [`BCryptGenRandom`] |
| //! | macOS | `*‑apple‑darwin` | [`getentropy`][3] if available, otherwise [`/dev/urandom`][4] (identical to `/dev/random`) |
| //! | iOS, tvOS, watchOS | `*‑apple‑ios`, `*-apple-tvos`, `*-apple-watchos` | [`SecRandomCopyBytes`] |
| //! | FreeBSD | `*‑freebsd` | [`getrandom`][5] if available, otherwise [`kern.arandom`][6] |
| //! | OpenBSD | `*‑openbsd` | [`getentropy`][7] |
| //! | NetBSD | `*‑netbsd` | [`getrandom`][16] if available, otherwise [`kern.arandom`][8] |
| //! | Dragonfly BSD | `*‑dragonfly` | [`getrandom`][9] if available, otherwise [`/dev/urandom`][10] (identical to `/dev/random`) |
| //! | Solaris, illumos | `*‑solaris`, `*‑illumos` | [`getrandom`][11] if available, otherwise [`/dev/random`][12] |
| //! | Fuchsia OS | `*‑fuchsia` | [`cprng_draw`] |
| //! | Redox | `*‑redox` | `/dev/urandom` |
| //! | Haiku | `*‑haiku` | `/dev/urandom` (identical to `/dev/random`) |
| //! | Hermit | `*-hermit` | [`sys_read_entropy`] |
| //! | SGX | `x86_64‑*‑sgx` | [`RDRAND`] |
| //! | VxWorks | `*‑wrs‑vxworks‑*` | `randABytes` after checking entropy pool initialization with `randSecure` |
| //! | ESP-IDF | `*‑espidf` | [`esp_fill_random`] |
| //! | Emscripten | `*‑emscripten` | [`getentropy`][13] |
| //! | WASI | `wasm32‑wasi` | [`random_get`] |
| //! | Web Browser and Node.js | `wasm*‑*‑unknown` | [`Crypto.getRandomValues`] if available, then [`crypto.randomFillSync`] if on Node.js, see [WebAssembly support] |
| //! | SOLID | `*-kmc-solid_*` | `SOLID_RNG_SampleRandomBytes` |
| //! | Nintendo 3DS | `armv6k-nintendo-3ds` | [`getrandom`][1] |
| //! | QNX Neutrino | `*‑nto-qnx*` | [`/dev/urandom`][14] (identical to `/dev/random`) |
| //! | AIX | `*-ibm-aix` | [`/dev/urandom`][15] |
| //! |
| //! There is no blanket implementation on `unix` targets that reads from |
| //! `/dev/urandom`. This ensures all supported targets are using the recommended |
| //! interface and respect maximum buffer sizes. |
| //! |
| //! Pull Requests that add support for new targets to `getrandom` are always welcome. |
| //! |
| //! ## Unsupported targets |
| //! |
| //! By default, `getrandom` will not compile on unsupported targets, but certain |
| //! features allow a user to select a "fallback" implementation if no supported |
| //! implementation exists. |
| //! |
| //! All of the below mechanisms only affect unsupported |
| //! targets. Supported targets will _always_ use their supported implementations. |
| //! This prevents a crate from overriding a secure source of randomness |
| //! (either accidentally or intentionally). |
| //! |
| //! ### RDRAND on x86 |
| //! |
| //! *If the `rdrand` Cargo feature is enabled*, `getrandom` will fallback to using |
| //! the [`RDRAND`] instruction to get randomness on `no_std` `x86`/`x86_64` |
| //! targets. This feature has no effect on other CPU architectures. |
| //! |
| //! ### WebAssembly support |
| //! |
| //! This crate fully supports the |
| //! [`wasm32-wasi`](https://github.com/CraneStation/wasi) and |
| //! [`wasm32-unknown-emscripten`](https://www.hellorust.com/setup/emscripten/) |
| //! targets. However, the `wasm32-unknown-unknown` target (i.e. the target used |
| //! by `wasm-pack`) is not automatically |
| //! supported since, from the target name alone, we cannot deduce which |
| //! JavaScript interface is in use (or if JavaScript is available at all). |
| //! |
| //! Instead, *if the `js` Cargo feature is enabled*, this crate will assume |
| //! that you are building for an environment containing JavaScript, and will |
| //! call the appropriate methods. Both web browser (main window and Web Workers) |
| //! and Node.js environments are supported, invoking the methods |
| //! [described above](#supported-targets) using the [`wasm-bindgen`] toolchain. |
| //! |
| //! To enable the `js` Cargo feature, add the following to the `dependencies` |
| //! section in your `Cargo.toml` file: |
| //! ```toml |
| //! [dependencies] |
| //! getrandom = { version = "0.2", features = ["js"] } |
| //! ``` |
| //! |
| //! This can be done even if `getrandom` is not a direct dependency. Cargo |
| //! allows crates to enable features for indirect dependencies. |
| //! |
| //! This feature should only be enabled for binary, test, or benchmark crates. |
| //! Library crates should generally not enable this feature, leaving such a |
| //! decision to *users* of their library. Also, libraries should not introduce |
| //! their own `js` features *just* to enable `getrandom`'s `js` feature. |
| //! |
| //! This feature has no effect on targets other than `wasm32-unknown-unknown`. |
| //! |
| //! #### Node.js ES module support |
| //! |
| //! Node.js supports both [CommonJS modules] and [ES modules]. Due to |
| //! limitations in wasm-bindgen's [`module`] support, we cannot directly |
| //! support ES Modules running on Node.js. However, on Node v15 and later, the |
| //! module author can add a simple shim to support the Web Cryptography API: |
| //! ```js |
| //! import { webcrypto } from 'node:crypto' |
| //! globalThis.crypto = webcrypto |
| //! ``` |
| //! This crate will then use the provided `webcrypto` implementation. |
| //! |
| //! ### Custom implementations |
| //! |
| //! The [`register_custom_getrandom!`] macro allows a user to mark their own |
| //! function as the backing implementation for [`getrandom`]. See the macro's |
| //! documentation for more information about writing and registering your own |
| //! custom implementations. |
| //! |
| //! Note that registering a custom implementation only has an effect on targets |
| //! that would otherwise not compile. Any supported targets (including those |
| //! using `rdrand` and `js` Cargo features) continue using their normal |
| //! implementations even if a function is registered. |
| //! |
| //! ## Early boot |
| //! |
| //! Sometimes, early in the boot process, the OS has not collected enough |
| //! entropy to securely seed its RNG. This is especially common on virtual |
| //! machines, where standard "random" events are hard to come by. |
| //! |
| //! Some operating system interfaces always block until the RNG is securely |
| //! seeded. This can take anywhere from a few seconds to more than a minute. |
| //! A few (Linux, NetBSD and Solaris) offer a choice between blocking and |
| //! getting an error; in these cases, we always choose to block. |
| //! |
| //! On Linux (when the `getrandom` system call is not available), reading from |
| //! `/dev/urandom` never blocks, even when the OS hasn't collected enough |
| //! entropy yet. To avoid returning low-entropy bytes, we first poll |
| //! `/dev/random` and only switch to `/dev/urandom` once this has succeeded. |
| //! |
| //! On OpenBSD, this kind of entropy accounting isn't available, and on |
| //! NetBSD, blocking on it is discouraged. On these platforms, nonblocking |
| //! interfaces are used, even when reliable entropy may not be available. |
| //! On the platforms where it is used, the reliability of entropy accounting |
| //! itself isn't free from controversy. This library provides randomness |
| //! sourced according to the platform's best practices, but each platform has |
| //! its own limits on the grade of randomness it can promise in environments |
| //! with few sources of entropy. |
| //! |
| //! ## Error handling |
| //! |
| //! We always choose failure over returning known insecure "random" bytes. In |
| //! general, on supported platforms, failure is highly unlikely, though not |
| //! impossible. If an error does occur, then it is likely that it will occur |
| //! on every call to `getrandom`, hence after the first successful call one |
| //! can be reasonably confident that no errors will occur. |
| //! |
| //! [1]: http://man7.org/linux/man-pages/man2/getrandom.2.html |
| //! [2]: http://man7.org/linux/man-pages/man4/urandom.4.html |
| //! [3]: https://www.unix.com/man-page/mojave/2/getentropy/ |
| //! [4]: https://www.unix.com/man-page/mojave/4/urandom/ |
| //! [5]: https://www.freebsd.org/cgi/man.cgi?query=getrandom&manpath=FreeBSD+12.0-stable |
| //! [6]: https://www.freebsd.org/cgi/man.cgi?query=random&sektion=4 |
| //! [7]: https://man.openbsd.org/getentropy.2 |
| //! [8]: https://man.netbsd.org/sysctl.7 |
| //! [9]: https://leaf.dragonflybsd.org/cgi/web-man?command=getrandom |
| //! [10]: https://leaf.dragonflybsd.org/cgi/web-man?command=random&section=4 |
| //! [11]: https://docs.oracle.com/cd/E88353_01/html/E37841/getrandom-2.html |
| //! [12]: https://docs.oracle.com/cd/E86824_01/html/E54777/random-7d.html |
| //! [13]: https://github.com/emscripten-core/emscripten/pull/12240 |
| //! [14]: https://www.qnx.com/developers/docs/7.1/index.html#com.qnx.doc.neutrino.utilities/topic/r/random.html |
| //! [15]: https://www.ibm.com/docs/en/aix/7.3?topic=files-random-urandom-devices |
| //! [16]: https://man.netbsd.org/getrandom.2 |
| //! |
| //! [`BCryptGenRandom`]: https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom |
| //! [`Crypto.getRandomValues`]: https://www.w3.org/TR/WebCryptoAPI/#Crypto-method-getRandomValues |
| //! [`RDRAND`]: https://software.intel.com/en-us/articles/intel-digital-random-number-generator-drng-software-implementation-guide |
| //! [`SecRandomCopyBytes`]: https://developer.apple.com/documentation/security/1399291-secrandomcopybytes?language=objc |
| //! [`cprng_draw`]: https://fuchsia.dev/fuchsia-src/zircon/syscalls/cprng_draw |
| //! [`crypto.randomFillSync`]: https://nodejs.org/api/crypto.html#cryptorandomfillsyncbuffer-offset-size |
| //! [`esp_fill_random`]: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/random.html#_CPPv415esp_fill_randomPv6size_t |
| //! [`random_get`]: https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/docs.md#-random_getbuf-pointeru8-buf_len-size---errno |
| //! [WebAssembly support]: #webassembly-support |
| //! [`wasm-bindgen`]: https://github.com/rustwasm/wasm-bindgen |
| //! [`module`]: https://rustwasm.github.io/wasm-bindgen/reference/attributes/on-js-imports/module.html |
| //! [CommonJS modules]: https://nodejs.org/api/modules.html |
| //! [ES modules]: https://nodejs.org/api/esm.html |
| //! [`sys_read_entropy`]: https://hermitcore.github.io/libhermit-rs/hermit/fn.sys_read_entropy.html |
| |
| </span><span class="attribute">#![doc( |
| html_logo_url = <span class="string">"https://www.rust-lang.org/logos/rust-logo-128x128-blk.png"</span>, |
| html_favicon_url = <span class="string">"https://www.rust-lang.org/favicon.ico"</span>, |
| html_root_url = <span class="string">"https://docs.rs/getrandom/0.2.9" |
| </span>)] |
| #![no_std] |
| #![warn(rust_2018_idioms, unused_lifetimes, missing_docs)] |
| #![cfg_attr(docsrs, feature(doc_cfg))] |
| |
| #[macro_use] |
| </span><span class="kw">extern crate </span>cfg_if; |
| |
| <span class="kw">use </span><span class="kw">crate</span>::util::{slice_as_uninit_mut, slice_assume_init_mut}; |
| <span class="kw">use </span>core::mem::MaybeUninit; |
| |
| <span class="kw">mod </span>error; |
| <span class="kw">mod </span>util; |
| <span class="comment">// To prevent a breaking change when targets are added, we always export the |
| // register_custom_getrandom macro, so old Custom RNG crates continue to build. |
| </span><span class="attribute">#[cfg(feature = <span class="string">"custom"</span>)] |
| </span><span class="kw">mod </span>custom; |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| </span><span class="kw">mod </span>error_impls; |
| |
| <span class="kw">pub use </span><span class="kw">crate</span>::error::Error; |
| |
| <span class="comment">// System-specific implementations. |
| // |
| // These should all provide getrandom_inner with the signature |
| // `fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error>`. |
| // The function MUST fully initialize `dest` when `Ok(())` is returned. |
| // The function MUST NOT ever write uninitialized bytes into `dest`, |
| // regardless of what value it returns. |
| </span><span class="macro">cfg_if! </span>{ |
| <span class="kw">if </span><span class="attribute">#[cfg(any(target_os = <span class="string">"haiku"</span>, target_os = <span class="string">"redox"</span>, target_os = <span class="string">"nto"</span>, target_os = <span class="string">"aix"</span>))] </span>{ |
| <span class="kw">mod </span>util_libc; |
| <span class="attribute">#[path = <span class="string">"use_file.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(any(target_os = <span class="string">"android"</span>, target_os = <span class="string">"linux"</span>))] </span>{ |
| <span class="kw">mod </span>util_libc; |
| <span class="kw">mod </span>use_file; |
| <span class="attribute">#[path = <span class="string">"linux_android.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(any(target_os = <span class="string">"illumos"</span>, target_os = <span class="string">"solaris"</span>))] </span>{ |
| <span class="kw">mod </span>util_libc; |
| <span class="kw">mod </span>use_file; |
| <span class="attribute">#[path = <span class="string">"solaris_illumos.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(any(target_os = <span class="string">"freebsd"</span>, target_os = <span class="string">"netbsd"</span>))] </span>{ |
| <span class="kw">mod </span>util_libc; |
| <span class="attribute">#[path = <span class="string">"bsd_arandom.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"dragonfly"</span>)] </span>{ |
| <span class="kw">mod </span>util_libc; |
| <span class="kw">mod </span>use_file; |
| <span class="attribute">#[path = <span class="string">"dragonfly.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"fuchsia"</span>)] </span>{ |
| <span class="attribute">#[path = <span class="string">"fuchsia.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(any(target_os = <span class="string">"ios"</span>, target_os = <span class="string">"watchos"</span>, target_os = <span class="string">"tvos"</span>))] </span>{ |
| <span class="attribute">#[path = <span class="string">"apple-other.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"macos"</span>)] </span>{ |
| <span class="kw">mod </span>util_libc; |
| <span class="kw">mod </span>use_file; |
| <span class="attribute">#[path = <span class="string">"macos.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"openbsd"</span>)] </span>{ |
| <span class="kw">mod </span>util_libc; |
| <span class="attribute">#[path = <span class="string">"openbsd.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(all(target_arch = <span class="string">"wasm32"</span>, target_os = <span class="string">"wasi"</span>))] </span>{ |
| <span class="attribute">#[path = <span class="string">"wasi.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"hermit"</span>)] </span>{ |
| <span class="attribute">#[path = <span class="string">"hermit.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"vxworks"</span>)] </span>{ |
| <span class="kw">mod </span>util_libc; |
| <span class="attribute">#[path = <span class="string">"vxworks.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"solid_asp3"</span>)] </span>{ |
| <span class="attribute">#[path = <span class="string">"solid.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"espidf"</span>)] </span>{ |
| <span class="attribute">#[path = <span class="string">"espidf.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(windows)] </span>{ |
| <span class="attribute">#[path = <span class="string">"windows.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(all(target_os = <span class="string">"horizon"</span>, target_arch = <span class="string">"arm"</span>))] </span>{ |
| <span class="comment">// We check for target_arch = "arm" because the Nintendo Switch also |
| // uses Horizon OS (it is aarch64). |
| </span><span class="kw">mod </span>util_libc; |
| <span class="attribute">#[path = <span class="string">"3ds.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(target_os = <span class="string">"emscripten"</span>)] </span>{ |
| <span class="kw">mod </span>util_libc; |
| <span class="attribute">#[path = <span class="string">"emscripten.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(all(target_arch = <span class="string">"x86_64"</span>, target_env = <span class="string">"sgx"</span>))] </span>{ |
| <span class="attribute">#[path = <span class="string">"rdrand.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(all(feature = <span class="string">"rdrand"</span>, |
| any(target_arch = <span class="string">"x86_64"</span>, target_arch = <span class="string">"x86"</span>)))] </span>{ |
| <span class="attribute">#[path = <span class="string">"rdrand.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(all(feature = <span class="string">"js"</span>, |
| any(target_arch = <span class="string">"wasm32"</span>, target_arch = <span class="string">"wasm64"</span>), |
| target_os = <span class="string">"unknown"</span>))] </span>{ |
| <span class="attribute">#[path = <span class="string">"js.rs"</span>] </span><span class="kw">mod </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(feature = <span class="string">"custom"</span>)] </span>{ |
| <span class="kw">use </span>custom <span class="kw">as </span>imp; |
| } <span class="kw">else if </span><span class="attribute">#[cfg(all(any(target_arch = <span class="string">"wasm32"</span>, target_arch = <span class="string">"wasm64"</span>), |
| target_os = <span class="string">"unknown"</span>))] </span>{ |
| <span class="macro">compile_error!</span>(<span class="string">"the wasm*-unknown-unknown targets are not supported by \ |
| default, you may need to enable the \"js\" feature. \ |
| For more information see: \ |
| https://docs.rs/getrandom/#webassembly-support"</span>); |
| } <span class="kw">else </span>{ |
| <span class="macro">compile_error!</span>(<span class="string">"target is not supported, for more information see: \ |
| https://docs.rs/getrandom/#unsupported-targets"</span>); |
| } |
| } |
| |
| <span class="doccomment">/// Fill `dest` with random bytes from the system's preferred random number |
| /// source. |
| /// |
| /// This function returns an error on any failure, including partial reads. We |
| /// make no guarantees regarding the contents of `dest` on error. If `dest` is |
| /// empty, `getrandom` immediately returns success, making no calls to the |
| /// underlying operating system. |
| /// |
| /// Blocking is possible, at least during early boot; see module documentation. |
| /// |
| /// In general, `getrandom` will be fast enough for interactive usage, though |
| /// significantly slower than a user-space CSPRNG; for the latter consider |
| /// [`rand::thread_rng`](https://docs.rs/rand/*/rand/fn.thread_rng.html). |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>getrandom(dest: <span class="kw-2">&mut </span>[u8]) -> <span class="prelude-ty">Result</span><(), Error> { |
| <span class="comment">// SAFETY: The `&mut MaybeUninit<_>` reference doesn't escape, and |
| // `getrandom_uninit` guarantees it will never de-initialize any part of |
| // `dest`. |
| </span>getrandom_uninit(<span class="kw">unsafe </span>{ slice_as_uninit_mut(dest) })<span class="question-mark">?</span>; |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="doccomment">/// Version of the `getrandom` function which fills `dest` with random bytes |
| /// returns a mutable reference to those bytes. |
| /// |
| /// On successful completion this function is guaranteed to return a slice |
| /// which points to the same memory as `dest` and has the same length. |
| /// In other words, it's safe to assume that `dest` is initialized after |
| /// this function has returned `Ok`. |
| /// |
| /// No part of `dest` will ever be de-initialized at any point, regardless |
| /// of what is returned. |
| /// |
| /// # Examples |
| /// |
| /// ```ignore |
| /// # // We ignore this test since `uninit_array` is unstable. |
| /// #![feature(maybe_uninit_uninit_array)] |
| /// # fn main() -> Result<(), getrandom::Error> { |
| /// let mut buf = core::mem::MaybeUninit::uninit_array::<1024>(); |
| /// let buf: &mut [u8] = getrandom::getrandom_uninit(&mut buf)?; |
| /// # Ok(()) } |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>getrandom_uninit(dest: <span class="kw-2">&mut </span>[MaybeUninit<u8>]) -> <span class="prelude-ty">Result</span><<span class="kw-2">&mut </span>[u8], Error> { |
| <span class="kw">if </span>!dest.is_empty() { |
| imp::getrandom_inner(dest)<span class="question-mark">?</span>; |
| } |
| <span class="comment">// SAFETY: `dest` has been fully initialized by `imp::getrandom_inner` |
| // since it returned `Ok`. |
| </span><span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ slice_assume_init_mut(dest) }) |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="getrandom" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |