diff options
Diffstat (limited to 'rand/rand_core')
| -rw-r--r-- | rand/rand_core/CHANGELOG.md | 31 | ||||
| -rw-r--r-- | rand/rand_core/Cargo.toml | 16 | ||||
| -rw-r--r-- | rand/rand_core/README.md | 31 | ||||
| -rw-r--r-- | rand/rand_core/src/block.rs | 185 | ||||
| -rw-r--r-- | rand/rand_core/src/error.rs | 267 | ||||
| -rw-r--r-- | rand/rand_core/src/impls.rs | 15 | ||||
| -rw-r--r-- | rand/rand_core/src/lib.rs | 246 | ||||
| -rw-r--r-- | rand/rand_core/src/os.rs | 85 |
8 files changed, 472 insertions, 404 deletions
diff --git a/rand/rand_core/CHANGELOG.md b/rand/rand_core/CHANGELOG.md index 2cbb259..dfdd692 100644 --- a/rand/rand_core/CHANGELOG.md +++ b/rand/rand_core/CHANGELOG.md @@ -4,30 +4,55 @@ All notable changes to this project will be documented in this file. The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html). +## [0.5.1] - 2019-08-28 +- `OsRng` added to `rand_core` (#863) +- `Error::INTERNAL_START` and `Error::CUSTOM_START` constants (#864) +- `Error::raw_os_error` method (#864) +- `Debug` and `Display` formatting for `getrandom` error codes without `std` (#864) +### Changed +- `alloc` feature in `no_std` is available since Rust 1.36 (#856) +- Added `#[inline]` to `Error` conversion methods (#864) + +## [0.5.0] - 2019-06-06 +### Changed +- Enable testing with Miri and fix incorrect pointer usages (#779, #780, #781, #783, #784) +- Rewrite `Error` type and adjust API (#800) +- Adjust usage of `#[inline]` for `BlockRng` and `BlockRng64` + +## [0.4.0] - 2019-01-24 +### Changed +- Disable the `std` feature by default (#702) + ## [0.3.0] - 2018-09-24 +### Added - Add `SeedableRng::seed_from_u64` for convenient seeding. (#537) ## [0.2.1] - 2018-06-08 +### Added - References to a `CryptoRng` now also implement `CryptoRng`. (#470) ## [0.2.0] - 2018-05-21 +### Changed - Enable the `std` feature by default. (#409) - Remove `BlockRng{64}::inner` and `BlockRng::inner_mut`; instead making `core` public -- Add `BlockRng{64}::index` and `BlockRng{64}::generate_and_set`. (#374, #419) - Change `BlockRngCore::Results` bound to also require `AsMut<[Self::Item]>`. (#419) +### Added +- Add `BlockRng{64}::index` and `BlockRng{64}::generate_and_set`. (#374, #419) - Implement `std::io::Read` for RngCore. (#434) ## [0.1.0] - 2018-04-17 -(Split out of the Rand crate, changes here are relative to rand 0.4.2) +(Split out of the Rand crate, changes here are relative to rand 0.4.2.) +### Added - `RngCore` and `SeedableRng` are now part of `rand_core`. (#288) - Add modules to help implementing RNGs `impl` and `le`. (#209, #228) - Add `Error` and `ErrorKind`. (#225) - Add `CryptoRng` marker trait. (#273) - Add `BlockRngCore` trait. (#281) - Add `BlockRng` and `BlockRng64` wrappers to help implementations. (#281, #325) +- Add `RngCore::try_fill_bytes`. (#225) +### Changed - Revise the `SeedableRng` trait. (#233) - Remove default implementations for `RngCore::next_u64` and `RngCore::fill_bytes`. (#288) -- Add `RngCore::try_fill_bytes`. (#225) ## [0.0.1] - 2017-09-14 (yanked) Experimental version as part of the rand crate refactor. diff --git a/rand/rand_core/Cargo.toml b/rand/rand_core/Cargo.toml index 1678773..e52af5f 100644 --- a/rand/rand_core/Cargo.toml +++ b/rand/rand_core/Cargo.toml @@ -1,28 +1,28 @@ [package] name = "rand_core" -version = "0.3.0" +version = "0.5.1" authors = ["The Rand Project Developers", "The Rust Project Developers"] -license = "MIT/Apache-2.0" +license = "MIT OR Apache-2.0" readme = "README.md" repository = "https://github.com/rust-random/rand" -documentation = "https://rust-random.github.io/rand/rand_core" +documentation = "https://rust-random.github.io/rand/rand_core/" homepage = "https://crates.io/crates/rand_core" description = """ Core random number generator traits and tools for implementation. """ keywords = ["random", "rng"] categories = ["algorithms", "no-std"] +edition = "2018" [badges] travis-ci = { repository = "rust-random/rand" } appveyor = { repository = "rust-random/rand" } [features] -default = ["std"] -std = ["alloc"] # use std library; should be default but for above bug +std = ["alloc", "getrandom", "getrandom/std"] # use std library; should be default but for above bug alloc = [] # enables Vec and Box support without std -serde1 = ["serde", "serde_derive"] # enables serde for BlockRng wrapper +serde1 = ["serde"] # enables serde for BlockRng wrapper [dependencies] -serde = { version = "1", optional = true } -serde_derive = { version = "^1.0.38", optional = true } +serde = { version = "1", features = ["derive"], optional = true } +getrandom = { version = "0.1", optional = true } diff --git a/rand/rand_core/README.md b/rand/rand_core/README.md index dee6504..467e66f 100644 --- a/rand/rand_core/README.md +++ b/rand/rand_core/README.md @@ -6,7 +6,7 @@ [](https://rust-random.github.io/book/) [](https://rust-random.github.io/rand/rand_core) [](https://docs.rs/rand_core) -[](https://github.com/rust-random/rand#rust-version-requirements) +[](https://github.com/rust-random/rand#rust-version-requirements) Core traits and error types of the [rand] library, plus tools for implementing RNGs. @@ -25,7 +25,7 @@ Links: - [API documentation (master)](https://rust-random.github.io/rand/rand_core) - [API documentation (docs.rs)](https://docs.rs/rand_core) -- [Changelog](CHANGELOG.md) +- [Changelog](https://github.com/rust-random/rand/blob/master/rand_core/CHANGELOG.md) [rand]: https://crates.io/crates/rand @@ -40,17 +40,34 @@ The `rand_core` crate provides: The traits and error types are also available via `rand`. +## Versions + +The current version is: +``` +rand_core = "0.5.0" +``` + +Rand libs have inter-dependencies and make use of the +[semver trick](https://github.com/dtolnay/semver-trick/) in order to make traits +compatible across crate versions. (This is especially important for `RngCore` +and `SeedableRng`.) A few crate releases are thus compatibility shims, +depending on the *next* lib version (e.g. `rand_core` versions `0.2.2` and +`0.3.1`). This means, for example, that `rand_core_0_4_0::SeedableRng` and +`rand_core_0_3_0::SeedableRng` are distinct, incompatible traits, which can +cause build errors. Usually, running `cargo update` is enough to fix any issues. + ## Crate Features `rand_core` supports `no_std` and `alloc`-only configurations, as well as full `std` functionality. The differences between `no_std` and full `std` are small, -comprising `RngCore` support for `Box<R>` types where `R: RngCore`, as well as +comprising `RngCore` support for `Box<R>` types where `R: RngCore`, +`std::io::Read` support for types supporting `RngCore`, and extensions to the `Error` type's functionality. -Due to [rust-lang/cargo#1596](https://github.com/rust-lang/cargo/issues/1596), -`rand_core` is built without `std` support by default. Since features are -unioned across the whole dependency tree, any crate using `rand` with its -default features will also enable `std` support in `rand_core`. +The `std` feature is *not enabled by default*. This is primarily to avoid build +problems where one crate implicitly requires `rand_core` with `std` support and +another crate requires `rand` *without* `std` support. However, the `rand` crate +continues to enable `std` support by default, both for itself and `rand_core`. The `serde1` feature can be used to derive `Serialize` and `Deserialize` for RNG implementations that use the `BlockRng` or `BlockRng64` wrappers. diff --git a/rand/rand_core/src/block.rs b/rand/rand_core/src/block.rs index de480e4..0ab7458 100644 --- a/rand/rand_core/src/block.rs +++ b/rand/rand_core/src/block.rs @@ -16,55 +16,55 @@ //! implementations only need to concern themselves with generation of the //! block, not the various [`RngCore`] methods (especially [`fill_bytes`], where //! the optimal implementations are not trivial), and this allows -//! [`ReseedingRng`] perform periodic reseeding with very low overhead. +//! `ReseedingRng` (see [`rand`](https://docs.rs/rand) crate) perform periodic +//! reseeding with very low overhead. //! //! # Example -//! +//! //! ```norun //! use rand_core::block::{BlockRngCore, BlockRng}; -//! +//! //! struct MyRngCore; -//! +//! //! impl BlockRngCore for MyRngCore { //! type Results = [u32; 16]; -//! +//! //! fn generate(&mut self, results: &mut Self::Results) { //! unimplemented!() //! } //! } -//! +//! //! impl SeedableRng for MyRngCore { //! type Seed = unimplemented!(); //! fn from_seed(seed: Self::Seed) -> Self { //! unimplemented!() //! } //! } -//! +//! //! // optionally, also implement CryptoRng for MyRngCore -//! +//! //! // Final RNG. //! type MyRng = BlockRng<u32, MyRngCore>; //! ``` -//! -//! [`BlockRngCore`]: trait.BlockRngCore.html -//! [`RngCore`]: ../trait.RngCore.html -//! [`fill_bytes`]: ../trait.RngCore.html#tymethod.fill_bytes -//! [`ReseedingRng`]: ../../rand/rngs/adapter/struct.ReseedingRng.html +//! +//! [`BlockRngCore`]: crate::block::BlockRngCore +//! [`fill_bytes`]: RngCore::fill_bytes use core::convert::AsRef; -use core::fmt; -use {RngCore, CryptoRng, SeedableRng, Error}; -use impls::{fill_via_u32_chunks, fill_via_u64_chunks}; +use core::{fmt, ptr}; +#[cfg(feature="serde1")] use serde::{Serialize, Deserialize}; +use crate::{RngCore, CryptoRng, SeedableRng, Error}; +use crate::impls::{fill_via_u32_chunks, fill_via_u64_chunks}; /// A trait for RNGs which do not generate random numbers individually, but in /// blocks (typically `[u32; N]`). This technique is commonly used by /// cryptographic RNGs to improve performance. -/// -/// See the [module documentation](index.html) for details. +/// +/// See the [module][crate::block] documentation for details. pub trait BlockRngCore { /// Results element type, e.g. `u32`. type Item; - + /// Results type. This is the 'block' an RNG implementing `BlockRngCore` /// generates, which will usually be an array like `[u32; 16]`. type Results: AsRef<[Self::Item]> + AsMut<[Self::Item]> + Default; @@ -105,15 +105,10 @@ pub trait BlockRngCore { /// /// For easy initialization `BlockRng` also implements [`SeedableRng`]. /// -/// [`BlockRngCore`]: BlockRngCore.t.html -/// [`BlockRngCore::generate`]: trait.BlockRngCore.html#tymethod.generate -/// [`BlockRng64`]: struct.BlockRng64.html -/// [`RngCore`]: ../RngCore.t.html -/// [`next_u32`]: ../trait.RngCore.html#tymethod.next_u32 -/// [`next_u64`]: ../trait.RngCore.html#tymethod.next_u64 -/// [`fill_bytes`]: ../trait.RngCore.html#tymethod.fill_bytes -/// [`try_fill_bytes`]: ../trait.RngCore.html#tymethod.try_fill_bytes -/// [`SeedableRng`]: ../SeedableRng.t.html +/// [`next_u32`]: RngCore::next_u32 +/// [`next_u64`]: RngCore::next_u64 +/// [`fill_bytes`]: RngCore::fill_bytes +/// [`try_fill_bytes`]: RngCore::try_fill_bytes #[derive(Clone)] #[cfg_attr(feature="serde1", derive(Serialize, Deserialize))] pub struct BlockRng<R: BlockRngCore + ?Sized> { @@ -137,6 +132,7 @@ impl<R: BlockRngCore + fmt::Debug> fmt::Debug for BlockRng<R> { impl<R: BlockRngCore> BlockRng<R> { /// Create a new `BlockRng` from an existing RNG implementing /// `BlockRngCore`. Results will be generated on first use. + #[inline] pub fn new(core: R) -> BlockRng<R>{ let results_empty = R::Results::default(); BlockRng { @@ -147,22 +143,25 @@ impl<R: BlockRngCore> BlockRng<R> { } /// Get the index into the result buffer. - /// + /// /// If this is equal to or larger than the size of the result buffer then /// the buffer is "empty" and `generate()` must be called to produce new /// results. + #[inline(always)] pub fn index(&self) -> usize { self.index } /// Reset the number of available results. /// This will force a new set of results to be generated on next use. + #[inline] pub fn reset(&mut self) { self.index = self.results.as_ref().len(); } /// Generate a new set of results immediately, setting the index to the /// given value. + #[inline] pub fn generate_and_set(&mut self, index: usize) { assert!(index < self.results.as_ref().len()); self.core.generate(&mut self.results); @@ -173,7 +172,7 @@ impl<R: BlockRngCore> BlockRng<R> { impl<R: BlockRngCore<Item=u32>> RngCore for BlockRng<R> where <R as BlockRngCore>::Results: AsRef<[u32]> + AsMut<[u32]> { - #[inline(always)] + #[inline] fn next_u32(&mut self) -> u32 { if self.index >= self.results.as_ref().len() { self.generate_and_set(0); @@ -184,12 +183,14 @@ where <R as BlockRngCore>::Results: AsRef<[u32]> + AsMut<[u32]> value } - #[inline(always)] + #[inline] fn next_u64(&mut self) -> u64 { let read_u64 = |results: &[u32], index| { - if cfg!(any(target_arch = "x86", target_arch = "x86_64")) { - // requires little-endian CPU supporting unaligned reads: - unsafe { *(&results[index] as *const u32 as *const u64) } + if cfg!(any(target_endian = "little")) { + // requires little-endian CPU + #[allow(clippy::cast_ptr_alignment)] // false positive + let ptr: *const u64 = results[index..=index+1].as_ptr() as *const u64; + unsafe { ptr::read_unaligned(ptr) } } else { let x = u64::from(results[index]); let y = u64::from(results[index + 1]); @@ -215,48 +216,7 @@ where <R as BlockRngCore>::Results: AsRef<[u32]> + AsMut<[u32]> } } - // As an optimization we try to write directly into the output buffer. - // This is only enabled for little-endian platforms where unaligned writes - // are known to be safe and fast. - #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] - fn fill_bytes(&mut self, dest: &mut [u8]) { - let mut filled = 0; - - // Continue filling from the current set of results - if self.index < self.results.as_ref().len() { - let (consumed_u32, filled_u8) = - fill_via_u32_chunks(&self.results.as_ref()[self.index..], - dest); - - self.index += consumed_u32; - filled += filled_u8; - } - - let len_remainder = - (dest.len() - filled) % (self.results.as_ref().len() * 4); - let end_direct = dest.len() - len_remainder; - - while filled < end_direct { - let dest_u32: &mut R::Results = unsafe { - &mut *(dest[filled..].as_mut_ptr() as - *mut <R as BlockRngCore>::Results) - }; - self.core.generate(dest_u32); - filled += self.results.as_ref().len() * 4; - self.index = self.results.as_ref().len(); - } - - if len_remainder > 0 { - self.core.generate(&mut self.results); - let (consumed_u32, _) = - fill_via_u32_chunks(self.results.as_ref(), - &mut dest[filled..]); - - self.index = consumed_u32; - } - } - - #[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))] + #[inline] fn fill_bytes(&mut self, dest: &mut [u8]) { let mut read_len = 0; while read_len < dest.len() { @@ -272,6 +232,7 @@ where <R as BlockRngCore>::Results: AsRef<[u32]> + AsMut<[u32]> } } + #[inline(always)] fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> { self.fill_bytes(dest); Ok(()) @@ -281,14 +242,17 @@ where <R as BlockRngCore>::Results: AsRef<[u32]> + AsMut<[u32]> impl<R: BlockRngCore + SeedableRng> SeedableRng for BlockRng<R> { type Seed = R::Seed; + #[inline(always)] fn from_seed(seed: Self::Seed) -> Self { Self::new(R::from_seed(seed)) } + #[inline(always)] fn seed_from_u64(seed: u64) -> Self { Self::new(R::seed_from_u64(seed)) } + #[inline(always)] fn from_rng<S: RngCore>(rng: S) -> Result<Self, Error> { Ok(Self::new(R::from_rng(rng)?)) } @@ -314,13 +278,10 @@ impl<R: BlockRngCore + SeedableRng> SeedableRng for BlockRng<R> { /// values. If the requested length is not a multiple of 8, some bytes will be /// discarded. /// -/// [`BlockRngCore`]: BlockRngCore.t.html -/// [`RngCore`]: ../RngCore.t.html -/// [`next_u32`]: ../trait.RngCore.html#tymethod.next_u32 -/// [`next_u64`]: ../trait.RngCore.html#tymethod.next_u64 -/// [`fill_bytes`]: ../trait.RngCore.html#tymethod.fill_bytes -/// [`try_fill_bytes`]: ../trait.RngCore.html#tymethod.try_fill_bytes -/// [`BlockRng`]: struct.BlockRng.html +/// [`next_u32`]: RngCore::next_u32 +/// [`next_u64`]: RngCore::next_u64 +/// [`fill_bytes`]: RngCore::fill_bytes +/// [`try_fill_bytes`]: RngCore::try_fill_bytes #[derive(Clone)] #[cfg_attr(feature="serde1", derive(Serialize, Deserialize))] pub struct BlockRng64<R: BlockRngCore + ?Sized> { @@ -346,6 +307,7 @@ impl<R: BlockRngCore + fmt::Debug> fmt::Debug for BlockRng64<R> { impl<R: BlockRngCore> BlockRng64<R> { /// Create a new `BlockRng` from an existing RNG implementing /// `BlockRngCore`. Results will be generated on first use. + #[inline] pub fn new(core: R) -> BlockRng64<R>{ let results_empty = R::Results::default(); BlockRng64 { @@ -361,12 +323,14 @@ impl<R: BlockRngCore> BlockRng64<R> { /// If this is equal to or larger than the size of the result buffer then /// the buffer is "empty" and `generate()` must be called to produce new /// results. + #[inline(always)] pub fn index(&self) -> usize { self.index } /// Reset the number of available results. /// This will force a new set of results to be generated on next use. + #[inline] pub fn reset(&mut self) { self.index = self.results.as_ref().len(); self.half_used = false; @@ -374,6 +338,7 @@ impl<R: BlockRngCore> BlockRng64<R> { /// Generate a new set of results immediately, setting the index to the /// given value. + #[inline] pub fn generate_and_set(&mut self, index: usize) { assert!(index < self.results.as_ref().len()); self.core.generate(&mut self.results); @@ -385,7 +350,7 @@ impl<R: BlockRngCore> BlockRng64<R> { impl<R: BlockRngCore<Item=u64>> RngCore for BlockRng64<R> where <R as BlockRngCore>::Results: AsRef<[u64]> + AsMut<[u64]> { - #[inline(always)] + #[inline] fn next_u32(&mut self) -> u32 { let mut index = self.index * 2 - self.half_used as usize; if index >= self.results.as_ref().len() * 2 { @@ -411,7 +376,7 @@ where <R as BlockRngCore>::Results: AsRef<[u64]> + AsMut<[u64]> } } - #[inline(always)] + #[inline] fn next_u64(&mut self) -> u64 { if self.index >= self.results.as_ref().len() { self.core.generate(&mut self.results); @@ -424,48 +389,7 @@ where <R as BlockRngCore>::Results: AsRef<[u64]> + AsMut<[u64]> value } - // As an optimization we try to write directly into the output buffer. - // This is only enabled for little-endian platforms where unaligned writes - // are known to be safe and fast. - #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] - fn fill_bytes(&mut self, dest: &mut [u8]) { - let mut filled = 0; - self.half_used = false; - - // Continue filling from the current set of results - if self.index < self.results.as_ref().len() { - let (consumed_u64, filled_u8) = - fill_via_u64_chunks(&self.results.as_ref()[self.index..], - dest); - - self.index += consumed_u64; - filled += filled_u8; - } - - let len_remainder = - (dest.len() - filled) % (self.results.as_ref().len() * 8); - let end_direct = dest.len() - len_remainder; - - while filled < end_direct { - let dest_u64: &mut R::Results = unsafe { - ::core::mem::transmute(dest[filled..].as_mut_ptr()) - }; - self.core.generate(dest_u64); - filled += self.results.as_ref().len() * 8; - self.index = self.results.as_ref().len(); - } - - if len_remainder > 0 { - self.core.generate(&mut self.results); - let (consumed_u64, _) = - fill_via_u64_chunks(&mut self.results.as_ref(), - &mut dest[filled..]); - - self.index = consumed_u64; - } - } - - #[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))] + #[inline] fn fill_bytes(&mut self, dest: &mut [u8]) { let mut read_len = 0; self.half_used = false; @@ -484,22 +408,27 @@ where <R as BlockRngCore>::Results: AsRef<[u64]> + AsMut<[u64]> } } + #[inline(always)] fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> { - Ok(self.fill_bytes(dest)) + self.fill_bytes(dest); + Ok(()) } } impl<R: BlockRngCore + SeedableRng> SeedableRng for BlockRng64<R> { type Seed = R::Seed; + #[inline(always)] fn from_seed(seed: Self::Seed) -> Self { Self::new(R::from_seed(seed)) } + #[inline(always)] fn seed_from_u64(seed: u64) -> Self { Self::new(R::seed_from_u64(seed)) } + #[inline(always)] fn from_rng<S: RngCore>(rng: S) -> Result<Self, Error> { Ok(Self::new(R::from_rng(rng)?)) } diff --git a/rand/rand_core/src/error.rs b/rand/rand_core/src/error.rs index 5a8459e..30b095c 100644 --- a/rand/rand_core/src/error.rs +++ b/rand/rand_core/src/error.rs @@ -9,169 +9,182 @@ //! Error types use core::fmt; +use core::num::NonZeroU32; -#[cfg(feature="std")] -use std::error::Error as stdError; -#[cfg(feature="std")] -use std::io; -/// Error kind which can be matched over. -#[derive(PartialEq, Eq, Debug, Copy, Clone)] -pub enum ErrorKind { - /// Feature is not available; not recoverable. - /// - /// This is the most permanent failure type and implies the error cannot be - /// resolved simply by retrying (e.g. the feature may not exist in this - /// build of the application or on the current platform). - Unavailable, - /// General failure; there may be a chance of recovery on retry. - /// - /// This is the catch-all kind for errors from known and unknown sources - /// which do not have a more specific kind / handling method. - /// - /// It is suggested to retry a couple of times or retry later when - /// handling; some error sources may be able to resolve themselves, - /// although this is not likely. - Unexpected, - /// A transient failure which likely can be resolved or worked around. - /// - /// This error kind exists for a few specific cases where it is known that - /// the error likely can be resolved internally, but is reported anyway. - Transient, - /// Not ready yet: recommended to try again a little later. - /// - /// This error kind implies the generator needs more time or needs some - /// other part of the application to do something else first before it is - /// ready for use; for example this may be used by external generators - /// which require time for initialization. - NotReady, - #[doc(hidden)] - __Nonexhaustive, +/// Error type of random number generators +/// +/// In order to be compatible with `std` and `no_std`, this type has two +/// possible implementations: with `std` a boxed `Error` trait object is stored, +/// while with `no_std` we merely store an error code. +pub struct Error { + #[cfg(feature="std")] + inner: Box<dyn std::error::Error + Send + Sync + 'static>, + #[cfg(not(feature="std"))] + code: NonZeroU32, } -impl ErrorKind { - /// True if this kind of error may resolve itself on retry. +impl Error { + /// Construct from any type supporting `std::error::Error` + /// + /// Available only when configured with `std`. /// - /// See also `should_wait()`. - pub fn should_retry(self) -> bool { - self != ErrorKind::Unavailable + /// See also `From<NonZeroU32>`, which is available with and without `std`. + #[cfg(feature="std")] + #[inline] + pub fn new<E>(err: E) -> Self + where E: Into<Box<dyn std::error::Error + Send + Sync + 'static>> + { + Error { inner: err.into() } } - /// True if we should retry but wait before retrying + /// Reference the inner error (`std` only) /// - /// This implies `should_retry()` is true. - pub fn should_wait(self) -> bool { - self == ErrorKind::NotReady + /// When configured with `std`, this is a trivial operation and never + /// panics. Without `std`, this method is simply unavailable. + #[cfg(feature="std")] + #[inline] + pub fn inner(&self) -> &(dyn std::error::Error + Send + Sync + 'static) { + &*self.inner } - /// A description of this error kind - pub fn description(self) -> &'static str { - match self { - ErrorKind::Unavailable => "permanently unavailable", - ErrorKind::Unexpected => "unexpected failure", - ErrorKind::Transient => "transient failure", - ErrorKind::NotReady => "not ready yet", - ErrorKind::__Nonexhaustive => unreachable!(), - } + /// Unwrap the inner error (`std` only) + /// + /// When configured with `std`, this is a trivial operation and never + /// panics. Without `std`, this method is simply unavailable. + #[cfg(feature="std")] + #[inline] + pub fn take_inner(self) -> Box<dyn std::error::Error + Send + Sync + 'static> { + self.inner } -} - + + /// Codes below this point represent OS Errors (i.e. positive i32 values). + /// Codes at or above this point, but below [`Error::CUSTOM_START`] are + /// reserved for use by the `rand` and `getrandom` crates. + pub const INTERNAL_START: u32 = 1 << 31; -/// Error type of random number generators -/// -/// This is a relatively simple error type, designed for compatibility with and -/// without the Rust `std` library. It embeds a "kind" code, a message (static -/// string only), and an optional chained cause (`std` only). The `kind` and -/// `msg` fields can be accessed directly; cause can be accessed via -/// `std::error::Error::cause` or `Error::take_cause`. Construction can only be -/// done via `Error::new` or `Error::with_cause`. -#[derive(Debug)] -pub struct Error { - /// The error kind - pub kind: ErrorKind, - /// The error message - pub msg: &'static str, - #[cfg(feature="std")] - cause: Option<Box<stdError + Send + Sync>>, -} + /// Codes at or above this point can be used by users to define their own + /// custom errors. + pub const CUSTOM_START: u32 = (1 << 31) + (1 << 30); -impl Error { - /// Create a new instance, with specified kind and a message. - pub fn new(kind: ErrorKind, msg: &'static str) -> Self { + /// Extract the raw OS error code (if this error came from the OS) + /// + /// This method is identical to `std::io::Error::raw_os_error()`, except + /// that it works in `no_std` contexts. If this method returns `None`, the + /// error value can still be formatted via the `Diplay` implementation. + #[inline] + pub fn raw_os_error(&self) -> Option<i32> { #[cfg(feature="std")] { - Error { kind, msg, cause: None } + if let Some(e) = self.inner.downcast_ref::<std::io::Error>() { + return e.raw_os_error(); + } } - #[cfg(not(feature="std"))] { - Error { kind, msg } + match self.code() { + Some(code) if u32::from(code) < Self::INTERNAL_START => + Some(u32::from(code) as i32), + _ => None, } } - - /// Create a new instance, with specified kind, message, and a - /// chained cause. - /// - /// Note: `stdError` is an alias for `std::error::Error`. - /// - /// If not targetting `std` (i.e. `no_std`), this function is replaced by - /// another with the same prototype, except that there are no bounds on the - /// type `E` (because both `Box` and `stdError` are unavailable), and the - /// `cause` is ignored. - #[cfg(feature="std")] - pub fn with_cause<E>(kind: ErrorKind, msg: &'static str, cause: E) -> Self - where E: Into<Box<stdError + Send + Sync>> - { - Error { kind, msg, cause: Some(cause.into()) } - } - - /// Create a new instance, with specified kind, message, and a - /// chained cause. + + /// Retrieve the error code, if any. /// - /// In `no_std` mode the *cause* is ignored. - #[cfg(not(feature="std"))] - pub fn with_cause<E>(kind: ErrorKind, msg: &'static str, _cause: E) -> Self { - Error { kind, msg } + /// If this `Error` was constructed via `From<NonZeroU32>`, then this method + /// will return this `NonZeroU32` code (for `no_std` this is always the + /// case). Otherwise, this method will return `None`. + #[inline] + pub fn code(&self) -> Option<NonZeroU32> { + #[cfg(feature="std")] { + self.inner.downcast_ref::<ErrorCode>().map(|c| c.0) + } + #[cfg(not(feature="std"))] { + Some(self.code) + } } - - /// Take the cause, if any. This allows the embedded cause to be extracted. - /// This uses `Option::take`, leaving `self` with no cause. - #[cfg(feature="std")] - pub fn take_cause(&mut self) -> Option<Box<stdError + Send + Sync>> { - self.cause.take() +} + +impl fmt::Debug for Error { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + #[cfg(feature="std")] { + write!(f, "Error {{ inner: {:?} }}", self.inner) + } + #[cfg(all(feature="getrandom", not(feature="std")))] { + getrandom::Error::from(self.code).fmt(f) + } + #[cfg(not(feature="getrandom"))] { + write!(f, "Error {{ code: {} }}", self.code) + } } } impl fmt::Display for Error { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { #[cfg(feature="std")] { - if let Some(ref cause) = self.cause { - return write!(f, "{} ({}); cause: {}", - self.msg, self.kind.description(), cause); - } + write!(f, "{}", self.inner) + } + #[cfg(all(feature="getrandom", not(feature="std")))] { + getrandom::Error::from(self.code).fmt(f) + } + #[cfg(not(feature="getrandom"))] { + write!(f, "error code {}", self.code) } - write!(f, "{} ({})", self.msg, self.kind.description()) } } -#[cfg(feature="std")] -impl stdError for Error { - fn description(&self) -> &str { - self.msg +impl From<NonZeroU32> for Error { + #[inline] + fn from(code: NonZeroU32) -> Self { + #[cfg(feature="std")] { + Error { inner: Box::new(ErrorCode(code)) } + } + #[cfg(not(feature="std"))] { + Error { code } + } + } +} + +#[cfg(feature="getrandom")] +impl From<getrandom::Error> for Error { + #[inline] + fn from(error: getrandom::Error) -> Self { + #[cfg(feature="std")] { + Error { inner: Box::new(error) } + } + #[cfg(not(feature="std"))] { + Error { code: error.code() } + } } +} - fn cause(&self) -> Option<&stdError> { - self.cause.as_ref().map(|e| e.as_ref() as &stdError) +#[cfg(feature="std")] +impl std::error::Error for Error { + #[inline] + fn source(&self) -> Option<&(dyn std::error::Error + 'static)> { + self.inner.source() } } #[cfg(feature="std")] -impl From<Error> for io::Error { +impl From<Error> for std::io::Error { + #[inline] fn from(error: Error) -> Self { - use std::io::ErrorKind::*; - match error.kind { - ErrorKind::Unavailable => io::Error::new(NotFound, error), - ErrorKind::Unexpected | - ErrorKind::Transient => io::Error::new(Other, error), - ErrorKind::NotReady => io::Error::new(WouldBlock, error), - ErrorKind::__Nonexhaustive => unreachable!(), + if let Some(code) = error.raw_os_error() { + std::io::Error::from_raw_os_error(code) + } else { + std::io::Error::new(std::io::ErrorKind::Other, error) } } } + +#[cfg(feature="std")] +#[derive(Debug, Copy, Clone)] +struct ErrorCode(NonZeroU32); + +#[cfg(feature="std")] +impl fmt::Display for ErrorCode { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + write!(f, "error code {}", self.0) + } +} + +#[cfg(feature="std")] +impl std::error::Error for ErrorCode {} diff --git a/rand/rand_core/src/impls.rs b/rand/rand_core/src/impls.rs index 57bdd07..dee4ed1 100644 --- a/rand/rand_core/src/impls.rs +++ b/rand/rand_core/src/impls.rs @@ -17,12 +17,11 @@ //! to/from byte sequences, and since its purpose is reproducibility, //! non-reproducible sources (e.g. `OsRng`) need not bother with it. -use core::intrinsics::transmute; use core::ptr::copy_nonoverlapping; use core::slice; use core::cmp::min; use core::mem::size_of; -use RngCore; +use crate::RngCore; /// Implement `next_u64` via `next_u32`, little-endian order. @@ -44,21 +43,15 @@ pub fn fill_bytes_via_next<R: RngCore + ?Sized>(rng: &mut R, dest: &mut [u8]) { while left.len() >= 8 { let (l, r) = {left}.split_at_mut(8); left = r; - let chunk: [u8; 8] = unsafe { - transmute(rng.next_u64().to_le()) - }; + let chunk: [u8; 8] = rng.next_u64().to_le_bytes(); l.copy_from_slice(&chunk); } let n = left.len(); if n > 4 { - let chunk: [u8; 8] = unsafe { - transmute(rng.next_u64().to_le()) - }; + let chunk: [u8; 8] = rng.next_u64().to_le_bytes(); left.copy_from_slice(&chunk[..n]); } else if n > 0 { - let chunk: [u8; 4] = unsafe { - transmute(rng.next_u32().to_le()) - }; + let chunk: [u8; 4] = rng.next_u32().to_le_bytes(); left.copy_from_slice(&chunk[..n]); } } diff --git a/rand/rand_core/src/lib.rs b/rand/rand_core/src/lib.rs index a65db93..d8e0189 100644 --- a/rand/rand_core/src/lib.rs +++ b/rand/rand_core/src/lib.rs @@ -8,29 +8,24 @@ // except according to those terms. //! Random number generation traits -//! +//! //! This crate is mainly of interest to crates publishing implementations of -//! [`RngCore`]. Other users are encouraged to use the [rand] crate instead +//! [`RngCore`]. Other users are encouraged to use the [`rand`] crate instead //! which re-exports the main traits and error types. //! //! [`RngCore`] is the core trait implemented by algorithmic pseudo-random number //! generators and external random-number sources. -//! +//! //! [`SeedableRng`] is an extension trait for construction from fixed seeds and //! other random number generators. -//! +//! //! [`Error`] is provided for error-handling. It is safe to use in `no_std` //! environments. -//! +//! //! The [`impls`] and [`le`] sub-modules include a few small functions to assist //! implementation of [`RngCore`]. -//! -//! [rand]: https://crates.io/crates/rand -//! [`RngCore`]: trait.RngCore.html -//! [`SeedableRng`]: trait.SeedableRng.html -//! [`Error`]: struct.Error.html -//! [`impls`]: impls/index.html -//! [`le`]: le/index.html +//! +//! [`rand`]: https://docs.rs/rand #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk.png", html_favicon_url = "https://www.rust-lang.org/favicon.ico", @@ -40,59 +35,58 @@ #![deny(missing_debug_implementations)] #![doc(test(attr(allow(unused_variables), deny(warnings))))] -#![cfg_attr(not(feature="std"), no_std)] -#![cfg_attr(all(feature="alloc", not(feature="std")), feature(alloc))] +#![allow(clippy::unreadable_literal)] -#[cfg(feature="std")] extern crate core; -#[cfg(all(feature = "alloc", not(feature="std")))] extern crate alloc; -#[cfg(feature="serde1")] extern crate serde; -#[cfg(feature="serde1")] #[macro_use] extern crate serde_derive; +#![cfg_attr(not(feature="std"), no_std)] use core::default::Default; use core::convert::AsMut; use core::ptr::copy_nonoverlapping; +#[cfg(all(feature="alloc", not(feature="std")))] extern crate alloc; #[cfg(all(feature="alloc", not(feature="std")))] use alloc::boxed::Box; -pub use error::{ErrorKind, Error}; +pub use error::Error; +#[cfg(feature="getrandom")] pub use os::OsRng; mod error; pub mod block; pub mod impls; pub mod le; +#[cfg(feature="getrandom")] mod os; /// The core of a random number generator. -/// +/// /// This trait encapsulates the low-level functionality common to all /// generators, and is the "back end", to be implemented by generators. -/// End users should normally use [`Rng`] from the [rand] crate, which is -/// automatically implemented for every type implementing `RngCore`. -/// +/// End users should normally use the `Rng` trait from the [`rand`] crate, +/// which is automatically implemented for every type implementing `RngCore`. +/// /// Three different methods for generating random data are provided since the /// optimal implementation of each is dependent on the type of generator. There /// is no required relationship between the output of each; e.g. many /// implementations of [`fill_bytes`] consume a whole number of `u32` or `u64` /// values and drop any remaining unused bytes. -/// +/// /// The [`try_fill_bytes`] method is a variant of [`fill_bytes`] allowing error /// handling; it is not deemed sufficiently useful to add equivalents for /// [`next_u32`] or [`next_u64`] since the latter methods are almost always used /// with algorithmic generators (PRNGs), which are normally infallible. -/// +/// /// Algorithmic generators implementing [`SeedableRng`] should normally have /// *portable, reproducible* output, i.e. fix Endianness when converting values /// to avoid platform differences, and avoid making any changes which affect /// output (except by communicating that the release has breaking changes). -/// +/// /// Typically implementators will implement only one of the methods available /// in this trait directly, then use the helper functions from the -/// [`rand_core::impls`] module to implement the other methods. -/// +/// [`impls`] module to implement the other methods. +/// /// It is recommended that implementations also implement: -/// +/// /// - `Debug` with a custom implementation which *does not* print any internal /// state (at least, [`CryptoRng`]s should not risk leaking state through /// `Debug`). @@ -104,72 +98,69 @@ pub mod le; /// implement [`SeedableRng`], to guide users towards proper seeding. /// External / hardware RNGs can choose to implement `Default`. /// - `Eq` and `PartialEq` could be implemented, but are probably not useful. -/// +/// /// # Example -/// +/// /// A simple example, obviously not generating very *random* output: -/// +/// /// ``` /// #![allow(dead_code)] /// use rand_core::{RngCore, Error, impls}; -/// +/// /// struct CountingRng(u64); -/// +/// /// impl RngCore for CountingRng { /// fn next_u32(&mut self) -> u32 { /// self.next_u64() as u32 /// } -/// +/// /// fn next_u64(&mut self) -> u64 { /// self.0 += 1; /// self.0 /// } -/// +/// /// fn fill_bytes(&mut self, dest: &mut [u8]) { /// impls::fill_bytes_via_next(self, dest) /// } -/// +/// /// fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> { /// Ok(self.fill_bytes(dest)) /// } /// } /// ``` -/// -/// [rand]: https://crates.io/crates/rand -/// [`Rng`]: ../rand/trait.Rng.html -/// [`SeedableRng`]: trait.SeedableRng.html -/// [`rand_core::impls`]: ../rand_core/impls/index.html -/// [`try_fill_bytes`]: trait.RngCore.html#tymethod.try_fill_bytes -/// [`fill_bytes`]: trait.RngCore.html#tymethod.fill_bytes -/// [`next_u32`]: trait.RngCore.html#tymethod.next_u32 -/// [`next_u64`]: trait.RngCore.html#tymethod.next_u64 -/// [`CryptoRng`]: trait.CryptoRng.html +/// +/// [`rand`]: https://docs.rs/rand +/// [`try_fill_bytes`]: RngCore::try_fill_bytes +/// [`fill_bytes`]: RngCore::fill_bytes +/// [`next_u32`]: RngCore::next_u32 +/// [`next_u64`]: RngCore::next_u64 pub trait RngCore { /// Return the next random `u32`. /// /// RNGs must implement at least one method from this trait directly. In /// the case this method is not implemented directly, it can be implemented - /// using `self.next_u64() as u32` or - /// [via `fill_bytes`](../rand_core/impls/fn.next_u32_via_fill.html). + /// using `self.next_u64() as u32` or via + /// [`fill_bytes`](impls::next_u32_via_fill). fn next_u32(&mut self) -> u32; /// Return the next random `u64`. /// /// RNGs must implement at least one method from this trait directly. In /// the case this method is not implemented directly, it can be implemented - /// [via `next_u32`](../rand_core/impls/fn.next_u64_via_u32.html) or - /// [via `fill_bytes`](../rand_core/impls/fn.next_u64_via_fill.html). + /// via [`next_u32`](impls::next_u64_via_u32) or via + /// [`fill_bytes`](impls::next_u64_via_fill). fn next_u64(&mut self) -> u64; /// Fill `dest` with random data. /// /// RNGs must implement at least one method from this trait directly. In /// the case this method is not implemented directly, it can be implemented - /// [via `next_u*`](../rand_core/impls/fn.fill_bytes_via_next.html) or - /// via `try_fill_bytes`; if this generator can fail the implementation - /// must choose how best to handle errors here (e.g. panic with a - /// descriptive message or log a warning and retry a few times). - /// + /// via [`next_u*`](impls::fill_bytes_via_next) or + /// via [`try_fill_bytes`](RngCore::try_fill_bytes); if this generator can + /// fail the implementation must choose how best to handle errors here + /// (e.g. panic with a descriptive message or log a warning and retry a few + /// times). + /// /// This method should guarantee that `dest` is entirely filled /// with new data, and may panic if this is impossible /// (e.g. reading past the end of a file that is being used as the @@ -182,51 +173,46 @@ pub trait RngCore { /// generating random data thus making this the primary method implemented /// by external (true) RNGs (e.g. `OsRng`) which can fail. It may be used /// directly to generate keys and to seed (infallible) PRNGs. - /// + /// /// Other than error handling, this method is identical to [`fill_bytes`]; /// thus this may be implemented using `Ok(self.fill_bytes(dest))` or /// `fill_bytes` may be implemented with /// `self.try_fill_bytes(dest).unwrap()` or more specific error handling. - /// - /// [`fill_bytes`]: trait.RngCore.html#method.fill_bytes + /// + /// [`fill_bytes`]: RngCore::fill_bytes fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>; } /// A marker trait used to indicate that an [`RngCore`] or [`BlockRngCore`] /// implementation is supposed to be cryptographically secure. -/// +/// /// *Cryptographically secure generators*, also known as *CSPRNGs*, should /// satisfy an additional properties over other generators: given the first /// *k* bits of an algorithm's output /// sequence, it should not be possible using polynomial-time algorithms to /// predict the next bit with probability significantly greater than 50%. -/// +/// /// Some generators may satisfy an additional property, however this is not /// required by this trait: if the CSPRNG's state is revealed, it should not be /// computationally-feasible to reconstruct output prior to this. Some other /// generators allow backwards-computation and are consided *reversible*. -/// +/// /// Note that this trait is provided for guidance only and cannot guarantee /// suitability for cryptographic applications. In general it should only be /// implemented for well-reviewed code implementing well-regarded algorithms. -/// +/// /// Note also that use of a `CryptoRng` does not protect against other /// weaknesses such as seeding from a weak entropy source or leaking state. -/// -/// [`RngCore`]: trait.RngCore.html -/// [`BlockRngCore`]: ../rand_core/block/trait.BlockRngCore.html +/// +/// [`BlockRngCore`]: block::BlockRngCore pub trait CryptoRng {} /// A random number generator that can be explicitly seeded. /// /// This trait encapsulates the low-level functionality common to all /// pseudo-random number generators (PRNGs, or algorithmic generators). -/// -/// The [`rand::FromEntropy`] trait is automatically implemented for every type -/// implementing `SeedableRng`, providing a convenient `from_entropy()` -/// constructor. -/// -/// [`rand::FromEntropy`]: ../rand/trait.FromEntropy.html +/// +/// [`rand`]: https://docs.rs/rand pub trait SeedableRng: Sized { /// Seed type, which is restricted to types mutably-dereferencable as `u8` /// arrays (we recommend `[u8; N]` for some `N`). @@ -279,14 +265,18 @@ pub trait SeedableRng: Sized { /// /// PRNG implementations are allowed to assume that bits in the seed are /// well distributed. That means usually that the number of one and zero - /// bits are about equal, and values like 0, 1 and (size - 1) are unlikely. + /// bits are roughly equal, and values like 0, 1 and (size - 1) are unlikely. + /// Note that many non-cryptographic PRNGs will show poor quality output + /// if this is not adhered to. If you wish to seed from simple numbers, use + /// `seed_from_u64` instead. /// - /// PRNG implementations are recommended to be reproducible. A PRNG seeded - /// using this function with a fixed seed should produce the same sequence - /// of output in the future and on different architectures (with for example - /// different endianness). + /// All PRNG implementations should be reproducible unless otherwise noted: + /// given a fixed `seed`, the same sequence of output should be produced + /// on all runs, library versions and architectures (e.g. check endianness). + /// Any "value-breaking" changes to the generator should require bumping at + /// least the minor version and documentation of the change. /// - /// It is however not required that this function yield the same state as a + /// It is not required that this function yield the same state as a /// reference implementation of the PRNG given equivalent seed; if necessary /// another constructor replicating behaviour from a reference /// implementation can be added. @@ -297,17 +287,17 @@ pub trait SeedableRng: Sized { /// for example `0xBAD5EEDu32` or `0x0DDB1A5E5BAD5EEDu64` ("odd biases? bad /// seed"). This is assuming only a small number of values must be rejected. fn from_seed(seed: Self::Seed) -> Self; - + /// Create a new PRNG using a `u64` seed. - /// + /// /// This is a convenience-wrapper around `from_seed` to allow construction /// of any `SeedableRng` from a simple `u64` value. It is designed such that /// low Hamming Weight numbers like 0 and 1 can be used and should still /// result in good, independent seeds to the PRNG which is returned. - /// + /// /// This **is not suitable for cryptography**, as should be clear given that /// the input size is only 64 bits. - /// + /// /// Implementations for PRNGs *may* provide their own implementations of /// this function, but the default implementation should be good enough for /// all purposes. *Changing* the implementation of this function should be @@ -316,64 +306,80 @@ pub trait SeedableRng: Sized { // We use PCG32 to generate a u32 sequence, and copy to the seed const MUL: u64 = 6364136223846793005; const INC: u64 = 11634580027462260723; - + let mut seed = Self::Seed::default(); for chunk in seed.as_mut().chunks_mut(4) { // We advance the state first (to get away from the input value, // in case it has low Hamming Weight). state = state.wrapping_mul(MUL).wrapping_add(INC); - + // Use PCG output function with to_le to generate x: let xorshifted = (((state >> 18) ^ state) >> 27) as u32; let rot = (state >> 59) as u32; let x = xorshifted.rotate_right(rot).to_le(); - + unsafe { let p = &x as *const u32 as *const u8; copy_nonoverlapping(p, chunk.as_mut_ptr(), chunk.len()); } } - + Self::from_seed(seed) } - + /// Create a new PRNG seeded from another `Rng`. /// - /// This is the recommended way to initialize PRNGs with fresh entropy. The - /// [`FromEntropy`] trait provides a convenient `from_entropy` method - /// based on `from_rng`. - /// - /// Usage of this method is not recommended when reproducibility is required - /// since implementing PRNGs are not required to fix Endianness and are - /// allowed to modify implementations in new releases. - /// - /// It is important to use a good source of randomness to initialize the - /// PRNG. Cryptographic PRNG may be rendered insecure when seeded from a - /// non-cryptographic PRNG or with insufficient entropy. - /// Many non-cryptographic PRNGs will show statistical bias in their first - /// results if their seed numbers are small or if there is a simple pattern - /// between them. - /// - /// Prefer to seed from a strong external entropy source like [`OsRng`] or - /// from a cryptographic PRNG; if creating a new generator for cryptographic - /// uses you *must* seed from a strong source. - /// - /// Seeding a small PRNG from another small PRNG is possible, but - /// something to be careful with. An extreme example of how this can go - /// wrong is seeding an Xorshift RNG from another Xorshift RNG, which - /// will effectively clone the generator. In general seeding from a - /// generator which is hard to predict is probably okay. + /// This may be useful when needing to rapidly seed many PRNGs from a master + /// PRNG, and to allow forking of PRNGs. It may be considered deterministic. + /// + /// The master PRNG should be at least as high quality as the child PRNGs. + /// When seeding non-cryptographic child PRNGs, we recommend using a + /// different algorithm for the master PRNG (ideally a CSPRNG) to avoid + /// correlations between the child PRNGs. If this is not possible (e.g. + /// forking using small non-crypto PRNGs) ensure that your PRNG has a good + /// mixing function on the output or consider use of a hash function with + /// `from_seed`. + /// + /// Note that seeding `XorShiftRng` from another `XorShiftRng` provides an + /// extreme example of what can go wrong: the new PRNG will be a clone + /// of the parent. /// /// PRNG implementations are allowed to assume that a good RNG is provided /// for seeding, and that it is cryptographically secure when appropriate. - /// - /// [`FromEntropy`]: ../rand/trait.FromEntropy.html - /// [`OsRng`]: ../rand/rngs/struct.OsRng.html + /// As of `rand` 0.7 / `rand_core` 0.5, implementations overriding this + /// method should ensure the implementation satisfies reproducibility + /// (in prior versions this was not required). + /// + /// [`rand`]: https://docs.rs/rand + /// [`rand_os`]: https://docs.rs/rand_os fn from_rng<R: RngCore>(mut rng: R) -> Result<Self, Error> { let mut seed = Self::Seed::default(); rng.try_fill_bytes(seed.as_mut())?; Ok(Self::from_seed(seed)) } + + /// Creates a new instance of the RNG seeded via [`getrandom`]. + /// + /// This method is the recommended way to construct non-deterministic PRNGs + /// since it is convenient and secure. + /// + /// In case the overhead of using [`getrandom`] to seed *many* PRNGs is an + /// issue, one may prefer to seed from a local PRNG, e.g. + /// `from_rng(thread_rng()).unwrap()`. + /// + /// # Panics + /// + /// If [`getrandom`] is unable to provide secure entropy this method will panic. + /// + /// [`getrandom`]: https://docs.rs/getrandom + #[cfg(feature="getrandom")] + fn from_entropy() -> Self { + let mut seed = Self::Seed::default(); + if let Err(err) = getrandom::getrandom(seed.as_mut()) { + panic!("from_entropy failed: {}", err); + } + Self::from_seed(seed) + } } // Implement `RngCore` for references to an `RngCore`. @@ -428,7 +434,7 @@ impl<R: RngCore + ?Sized> RngCore for Box<R> { } #[cfg(feature="std")] -impl std::io::Read for RngCore { +impl std::io::Read for dyn RngCore { fn read(&mut self, buf: &mut [u8]) -> Result<usize, std::io::Error> { self.try_fill_bytes(buf)?; Ok(buf.len()) @@ -445,7 +451,7 @@ impl<R: CryptoRng + ?Sized> CryptoRng for Box<R> {} #[cfg(test)] mod test { use super::*; - + #[test] fn test_seed_from_u64() { struct SeedableNum(u64); @@ -457,7 +463,7 @@ mod test { SeedableNum(x[0]) } } - + const N: usize = 8; const SEEDS: [u64; N] = [0u64, 1, 2, 3, 4, 8, 16, -1i64 as u64]; let mut results = [0u64; N]; @@ -465,21 +471,21 @@ mod test { let SeedableNum(x) = SeedableNum::seed_from_u64(*seed); results[i] = x; } - + for (i1, r1) in results.iter().enumerate() { let weight = r1.count_ones(); // This is the binomial distribution B(64, 0.5), so chance of // weight < 20 is binocdf(19, 64, 0.5) = 7.8e-4, and same for // weight > 44. assert!(weight >= 20 && weight <= 44); - + for (i2, r2) in results.iter().enumerate() { if i1 == i2 { continue; } let diff_weight = (r1 ^ r2).count_ones(); assert!(diff_weight >= 20); } } - + // value-breakage test: assert_eq!(results[0], 5029875928683246316); } diff --git a/rand/rand_core/src/os.rs b/rand/rand_core/src/os.rs new file mode 100644 index 0000000..fc23a57 --- /dev/null +++ b/rand/rand_core/src/os.rs @@ -0,0 +1,85 @@ +// 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. + +//! Interface to the random number generator of the operating system. +// Note: keep this code in sync with the rand_os crate! + +use getrandom::getrandom; +use crate::{CryptoRng, RngCore, Error, impls}; + +/// A random number generator that retrieves randomness from from the +/// operating system. +/// +/// This is a zero-sized struct. It can be freely constructed with `OsRng`. +/// +/// The implementation is provided by the [getrandom] crate. Refer to +/// [getrandom] documentation for details. +/// +/// This struct is only available when specifying the crate feature `getrandom` +/// or `std`. When using the `rand` lib, it is also available as `rand::rngs::OsRng`. +/// +/// # Blocking and error handling +/// +/// It is possible that when used during early boot the first call to `OsRng` +/// will block until the system's RNG is initialised. It is also possible +/// (though highly unlikely) for `OsRng` to fail on some platforms, most +/// likely due to system mis-configuration. +/// +/// After the first successful call, it is highly unlikely that failures or +/// significant delays will occur (although performance should be expected to +/// be much slower than a user-space PRNG). +/// +/// # Usage example +/// ``` +/// use rand_core::{RngCore, OsRng}; +/// +/// let mut key = [0u8; 16]; +/// OsRng.fill_bytes(&mut key); +/// let random_u64 = OsRng.next_u64(); +/// ``` +/// +/// [getrandom]: https://crates.io/crates/getrandom +#[derive(Clone, Copy, Debug, Default)] +pub struct OsRng; + +impl CryptoRng for OsRng {} + +impl RngCore for OsRng { + fn next_u32(&mut self) -> u32 { + impls::next_u32_via_fill(self) + } + + fn next_u64(&mut self) -> u64 { + impls::next_u64_via_fill(self) + } + + fn fill_bytes(&mut self, dest: &mut [u8]) { + if let Err(e) = self.try_fill_bytes(dest) { + panic!("Error: {}", e); + } + } + + fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> { + getrandom(dest)?; + Ok(()) + } +} + +#[test] +fn test_os_rng() { + let x = OsRng.next_u64(); + let y = OsRng.next_u64(); + assert!(x != 0); + assert!(x != y); +} + +#[test] +fn test_construction() { + let mut rng = OsRng::default(); + assert!(rng.next_u64() != 0); +} |