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| </pre><pre class="rust"><code><span class="comment">// Copyright 2018 Developers of the Rand project.</span> |
| <span class="comment">// Copyright 2013 The Rust Project Developers.</span> |
| <span class="comment">//</span> |
| <span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span> |
| <span class="comment">// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span> |
| <span class="comment">// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your</span> |
| <span class="comment">// option. This file may not be copied, modified, or distributed</span> |
| <span class="comment">// except according to those terms.</span> |
| |
| <span class="doccomment">//! A wrapper around another PRNG that reseeds it after it</span> |
| <span class="doccomment">//! generates a certain number of random bytes.</span> |
| |
| <span class="kw">use</span> <span class="ident">core::mem::size_of</span>; |
| |
| <span class="kw">use</span> <span class="ident">rand_core::block</span>::{<span class="ident">BlockRng</span>, <span class="ident">BlockRngCore</span>}; |
| <span class="kw">use</span> <span class="ident">rand_core</span>::{<span class="ident">CryptoRng</span>, <span class="ident">Error</span>, <span class="ident">RngCore</span>, <span class="ident">SeedableRng</span>}; |
| |
| <span class="doccomment">/// A wrapper around any PRNG that implements [`BlockRngCore`], that adds the</span> |
| <span class="doccomment">/// ability to reseed it.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// `ReseedingRng` reseeds the underlying PRNG in the following cases:</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// - On a manual call to [`reseed()`].</span> |
| <span class="doccomment">/// - After `clone()`, the clone will be reseeded on first use.</span> |
| <span class="doccomment">/// - When a process is forked on UNIX, the RNGs in both the parent and child</span> |
| <span class="doccomment">/// processes will be reseeded just before the next call to</span> |
| <span class="doccomment">/// [`BlockRngCore::generate`], i.e. "soon". For ChaCha and Hc128 this is a</span> |
| <span class="doccomment">/// maximum of fifteen `u32` values before reseeding.</span> |
| <span class="doccomment">/// - After the PRNG has generated a configurable number of random bytes.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// # When should reseeding after a fixed number of generated bytes be used?</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Reseeding after a fixed number of generated bytes is never strictly</span> |
| <span class="doccomment">/// *necessary*. Cryptographic PRNGs don't have a limited number of bytes they</span> |
| <span class="doccomment">/// can output, or at least not a limit reachable in any practical way. There is</span> |
| <span class="doccomment">/// no such thing as 'running out of entropy'.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Occasionally reseeding can be seen as some form of 'security in depth'. Even</span> |
| <span class="doccomment">/// if in the future a cryptographic weakness is found in the CSPRNG being used,</span> |
| <span class="doccomment">/// or a flaw in the implementation, occasionally reseeding should make</span> |
| <span class="doccomment">/// exploiting it much more difficult or even impossible.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Use [`ReseedingRng::new`] with a `threshold` of `0` to disable reseeding</span> |
| <span class="doccomment">/// after a fixed number of generated bytes.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// # Limitations</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// It is recommended that a `ReseedingRng` (including `ThreadRng`) not be used</span> |
| <span class="doccomment">/// from a fork handler.</span> |
| <span class="doccomment">/// Use `OsRng` or `getrandom`, or defer your use of the RNG until later.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// # Error handling</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Although unlikely, reseeding the wrapped PRNG can fail. `ReseedingRng` will</span> |
| <span class="doccomment">/// never panic but try to handle the error intelligently through some</span> |
| <span class="doccomment">/// combination of retrying and delaying reseeding until later.</span> |
| <span class="doccomment">/// If handling the source error fails `ReseedingRng` will continue generating</span> |
| <span class="doccomment">/// data from the wrapped PRNG without reseeding.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Manually calling [`reseed()`] will not have this retry or delay logic, but</span> |
| <span class="doccomment">/// reports the error.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// # Example</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// ```</span> |
| <span class="doccomment">/// use rand::prelude::*;</span> |
| <span class="doccomment">/// use rand_chacha::ChaCha20Core; // Internal part of ChaChaRng that</span> |
| <span class="doccomment">/// // implements BlockRngCore</span> |
| <span class="doccomment">/// use rand::rngs::OsRng;</span> |
| <span class="doccomment">/// use rand::rngs::adapter::ReseedingRng;</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// let prng = ChaCha20Core::from_entropy();</span> |
| <span class="doccomment">/// let mut reseeding_rng = ReseedingRng::new(prng, 0, OsRng);</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// println!("{}", reseeding_rng.gen::<u64>());</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// let mut cloned_rng = reseeding_rng.clone();</span> |
| <span class="doccomment">/// assert!(reseeding_rng.gen::<u64>() != cloned_rng.gen::<u64>());</span> |
| <span class="doccomment">/// ```</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// [`BlockRngCore`]: rand_core::block::BlockRngCore</span> |
| <span class="doccomment">/// [`ReseedingRng::new`]: ReseedingRng::new</span> |
| <span class="doccomment">/// [`reseed()`]: ReseedingRng::reseed</span> |
| <span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span> |
| <span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">ReseedingRng</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span>(<span class="ident">BlockRng</span><span class="op"><</span><span class="ident">ReseedingCore</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span><span class="op">></span>) |
| <span class="kw">where</span> |
| <span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span>, |
| <span class="ident">Rsdr</span>: <span class="ident">RngCore</span>; |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> <span class="ident">ReseedingRng</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span>, |
| <span class="ident">Rsdr</span>: <span class="ident">RngCore</span>, |
| { |
| <span class="doccomment">/// Create a new `ReseedingRng` from an existing PRNG, combined with a RNG</span> |
| <span class="doccomment">/// to use as reseeder.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// `threshold` sets the number of generated bytes after which to reseed the</span> |
| <span class="doccomment">/// PRNG. Set it to zero to never reseed based on the number of generated</span> |
| <span class="doccomment">/// values.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">rng</span>: <span class="ident">R</span>, <span class="ident">threshold</span>: <span class="ident">u64</span>, <span class="ident">reseeder</span>: <span class="ident">Rsdr</span>) -> <span class="self">Self</span> { |
| <span class="ident">ReseedingRng</span>(<span class="ident">BlockRng::new</span>(<span class="ident">ReseedingCore::new</span>(<span class="ident">rng</span>, <span class="ident">threshold</span>, <span class="ident">reseeder</span>))) |
| } |
| |
| <span class="doccomment">/// Reseed the internal PRNG.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">reseed</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) -> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> { |
| <span class="self">self</span>.<span class="number">0</span>.<span class="ident">core</span>.<span class="ident">reseed</span>() |
| } |
| } |
| |
| <span class="comment">// TODO: this should be implemented for any type where the inner type</span> |
| <span class="comment">// implements RngCore, but we can't specify that because ReseedingCore is private</span> |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span>: <span class="ident">RngCore</span><span class="op">></span> <span class="ident">RngCore</span> <span class="kw">for</span> <span class="ident">ReseedingRng</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">R</span>: <span class="ident">BlockRngCore</span><span class="op"><</span><span class="ident">Item</span> <span class="op">=</span> <span class="ident">u32</span><span class="op">></span> <span class="op">+</span> <span class="ident">SeedableRng</span>, |
| <span class="op"><</span><span class="ident">R</span> <span class="kw">as</span> <span class="ident">BlockRngCore</span><span class="op">></span><span class="ident">::Results</span>: <span class="ident">AsRef</span><span class="op"><</span>[<span class="ident">u32</span>]<span class="op">></span> <span class="op">+</span> <span class="ident">AsMut</span><span class="op"><</span>[<span class="ident">u32</span>]<span class="op">></span>, |
| { |
| <span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span> |
| <span class="kw">fn</span> <span class="ident">next_u32</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) -> <span class="ident">u32</span> { |
| <span class="self">self</span>.<span class="number">0</span>.<span class="ident">next_u32</span>() |
| } |
| |
| <span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span> |
| <span class="kw">fn</span> <span class="ident">next_u64</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) -> <span class="ident">u64</span> { |
| <span class="self">self</span>.<span class="number">0</span>.<span class="ident">next_u64</span>() |
| } |
| |
| <span class="kw">fn</span> <span class="ident">fill_bytes</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&mut</span> [<span class="ident">u8</span>]) { |
| <span class="self">self</span>.<span class="number">0</span>.<span class="ident">fill_bytes</span>(<span class="ident">dest</span>) |
| } |
| |
| <span class="kw">fn</span> <span class="ident">try_fill_bytes</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&mut</span> [<span class="ident">u8</span>]) -> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> { |
| <span class="self">self</span>.<span class="number">0</span>.<span class="ident">try_fill_bytes</span>(<span class="ident">dest</span>) |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">ReseedingRng</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span> <span class="op">+</span> <span class="ident">Clone</span>, |
| <span class="ident">Rsdr</span>: <span class="ident">RngCore</span> <span class="op">+</span> <span class="ident">Clone</span>, |
| { |
| <span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="ident">ReseedingRng</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> { |
| <span class="comment">// Recreating `BlockRng` seems easier than cloning it and resetting</span> |
| <span class="comment">// the index.</span> |
| <span class="ident">ReseedingRng</span>(<span class="ident">BlockRng::new</span>(<span class="self">self</span>.<span class="number">0</span>.<span class="ident">core</span>.<span class="ident">clone</span>())) |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> <span class="ident">CryptoRng</span> <span class="kw">for</span> <span class="ident">ReseedingRng</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span> <span class="op">+</span> <span class="ident">CryptoRng</span>, |
| <span class="ident">Rsdr</span>: <span class="ident">RngCore</span> <span class="op">+</span> <span class="ident">CryptoRng</span>, |
| { |
| } |
| |
| <span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span> |
| <span class="kw">struct</span> <span class="ident">ReseedingCore</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> { |
| <span class="ident">inner</span>: <span class="ident">R</span>, |
| <span class="ident">reseeder</span>: <span class="ident">Rsdr</span>, |
| <span class="ident">threshold</span>: <span class="ident">i64</span>, |
| <span class="ident">bytes_until_reseed</span>: <span class="ident">i64</span>, |
| <span class="ident">fork_counter</span>: <span class="ident">usize</span>, |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> <span class="ident">BlockRngCore</span> <span class="kw">for</span> <span class="ident">ReseedingCore</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span>, |
| <span class="ident">Rsdr</span>: <span class="ident">RngCore</span>, |
| { |
| <span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="op"><</span><span class="ident">R</span> <span class="kw">as</span> <span class="ident">BlockRngCore</span><span class="op">></span><span class="ident">::Item</span>; |
| <span class="kw">type</span> <span class="ident">Results</span> <span class="op">=</span> <span class="op"><</span><span class="ident">R</span> <span class="kw">as</span> <span class="ident">BlockRngCore</span><span class="op">></span><span class="ident">::Results</span>; |
| |
| <span class="kw">fn</span> <span class="ident">generate</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">results</span>: <span class="kw-2">&mut</span> <span class="ident"><span class="self">Self</span>::Results</span>) { |
| <span class="kw">let</span> <span class="ident">global_fork_counter</span> <span class="op">=</span> <span class="ident">fork::get_fork_counter</span>(); |
| <span class="kw">if</span> <span class="self">self</span>.<span class="ident">bytes_until_reseed</span> <span class="op"><</span><span class="op">=</span> <span class="number">0</span> <span class="op">|</span><span class="op">|</span> <span class="self">self</span>.<span class="ident">is_forked</span>(<span class="ident">global_fork_counter</span>) { |
| <span class="comment">// We get better performance by not calling only `reseed` here</span> |
| <span class="comment">// and continuing with the rest of the function, but by directly</span> |
| <span class="comment">// returning from a non-inlined function.</span> |
| <span class="kw">return</span> <span class="self">self</span>.<span class="ident">reseed_and_generate</span>(<span class="ident">results</span>, <span class="ident">global_fork_counter</span>); |
| } |
| <span class="kw">let</span> <span class="ident">num_bytes</span> <span class="op">=</span> <span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() <span class="op">*</span> <span class="ident">size_of</span>::<span class="op"><</span><span class="ident"><span class="self">Self</span>::Item</span><span class="op">></span>(); |
| <span class="self">self</span>.<span class="ident">bytes_until_reseed</span> <span class="op">-</span><span class="op">=</span> <span class="ident">num_bytes</span> <span class="kw">as</span> <span class="ident">i64</span>; |
| <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">generate</span>(<span class="ident">results</span>); |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> <span class="ident">ReseedingCore</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span>, |
| <span class="ident">Rsdr</span>: <span class="ident">RngCore</span>, |
| { |
| <span class="doccomment">/// Create a new `ReseedingCore`.</span> |
| <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">rng</span>: <span class="ident">R</span>, <span class="ident">threshold</span>: <span class="ident">u64</span>, <span class="ident">reseeder</span>: <span class="ident">Rsdr</span>) -> <span class="self">Self</span> { |
| <span class="kw">use</span> <span class="ident">::core::i64::MAX</span>; |
| <span class="ident">fork::register_fork_handler</span>(); |
| |
| <span class="comment">// Because generating more values than `i64::MAX` takes centuries on</span> |
| <span class="comment">// current hardware, we just clamp to that value.</span> |
| <span class="comment">// Also we set a threshold of 0, which indicates no limit, to that</span> |
| <span class="comment">// value.</span> |
| <span class="kw">let</span> <span class="ident">threshold</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">threshold</span> <span class="op">==</span> <span class="number">0</span> { |
| <span class="ident">MAX</span> |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="ident">threshold</span> <span class="op"><</span><span class="op">=</span> <span class="ident">MAX</span> <span class="kw">as</span> <span class="ident">u64</span> { |
| <span class="ident">threshold</span> <span class="kw">as</span> <span class="ident">i64</span> |
| } <span class="kw">else</span> { |
| <span class="ident">MAX</span> |
| }; |
| |
| <span class="ident">ReseedingCore</span> { |
| <span class="ident">inner</span>: <span class="ident">rng</span>, |
| <span class="ident">reseeder</span>, |
| <span class="ident">threshold</span>: <span class="ident">threshold</span> <span class="kw">as</span> <span class="ident">i64</span>, |
| <span class="ident">bytes_until_reseed</span>: <span class="ident">threshold</span> <span class="kw">as</span> <span class="ident">i64</span>, |
| <span class="ident">fork_counter</span>: <span class="number">0</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Reseed the internal PRNG.</span> |
| <span class="kw">fn</span> <span class="ident">reseed</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) -> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> { |
| <span class="ident">R::from_rng</span>(<span class="kw-2">&mut</span> <span class="self">self</span>.<span class="ident">reseeder</span>).<span class="ident">map</span>(<span class="op">|</span><span class="ident">result</span><span class="op">|</span> { |
| <span class="self">self</span>.<span class="ident">bytes_until_reseed</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">threshold</span>; |
| <span class="self">self</span>.<span class="ident">inner</span> <span class="op">=</span> <span class="ident">result</span> |
| }) |
| } |
| |
| <span class="kw">fn</span> <span class="ident">is_forked</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">global_fork_counter</span>: <span class="ident">usize</span>) -> <span class="ident">bool</span> { |
| <span class="comment">// In theory, on 32-bit platforms, it is possible for</span> |
| <span class="comment">// `global_fork_counter` to wrap around after ~4e9 forks.</span> |
| <span class="comment">//</span> |
| <span class="comment">// This check will detect a fork in the normal case where</span> |
| <span class="comment">// `fork_counter < global_fork_counter`, and also when the difference</span> |
| <span class="comment">// between both is greater than `isize::MAX` (wrapped around).</span> |
| <span class="comment">//</span> |
| <span class="comment">// It will still fail to detect a fork if there have been more than</span> |
| <span class="comment">// `isize::MAX` forks, without any reseed in between. Seems unlikely</span> |
| <span class="comment">// enough.</span> |
| (<span class="self">self</span>.<span class="ident">fork_counter</span>.<span class="ident">wrapping_sub</span>(<span class="ident">global_fork_counter</span>) <span class="kw">as</span> <span class="ident">isize</span>) <span class="op"><</span> <span class="number">0</span> |
| } |
| |
| <span class="attribute">#[<span class="ident">inline</span>(<span class="ident">never</span>)]</span> |
| <span class="kw">fn</span> <span class="ident">reseed_and_generate</span>( |
| <span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">results</span>: <span class="kw-2">&mut</span> <span class="op"><</span><span class="self">Self</span> <span class="kw">as</span> <span class="ident">BlockRngCore</span><span class="op">></span><span class="ident">::Results</span>, <span class="ident">global_fork_counter</span>: <span class="ident">usize</span>, |
| ) { |
| <span class="attribute">#![<span class="ident">allow</span>(<span class="ident">clippy::if_same_then_else</span>)]</span> <span class="comment">// false positive</span> |
| <span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_forked</span>(<span class="ident">global_fork_counter</span>) { |
| <span class="macro">info!</span>(<span class="string">"Fork detected, reseeding RNG"</span>); |
| } <span class="kw">else</span> { |
| <span class="macro">trace!</span>(<span class="string">"Reseeding RNG (periodic reseed)"</span>); |
| } |
| |
| <span class="kw">let</span> <span class="ident">num_bytes</span> <span class="op">=</span> <span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() <span class="op">*</span> <span class="ident">size_of</span>::<span class="op"><</span><span class="op"><</span><span class="ident">R</span> <span class="kw">as</span> <span class="ident">BlockRngCore</span><span class="op">></span><span class="ident">::Item</span><span class="op">></span>(); |
| |
| <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Err</span>(<span class="ident">e</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">reseed</span>() { |
| <span class="macro">warn!</span>(<span class="string">"Reseeding RNG failed: {}"</span>, <span class="ident">e</span>); |
| <span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">e</span>; |
| } |
| <span class="self">self</span>.<span class="ident">fork_counter</span> <span class="op">=</span> <span class="ident">global_fork_counter</span>; |
| |
| <span class="self">self</span>.<span class="ident">bytes_until_reseed</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">threshold</span> <span class="op">-</span> <span class="ident">num_bytes</span> <span class="kw">as</span> <span class="ident">i64</span>; |
| <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">generate</span>(<span class="ident">results</span>); |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">ReseedingCore</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span> <span class="op">+</span> <span class="ident">Clone</span>, |
| <span class="ident">Rsdr</span>: <span class="ident">RngCore</span> <span class="op">+</span> <span class="ident">Clone</span>, |
| { |
| <span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="ident">ReseedingCore</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> { |
| <span class="ident">ReseedingCore</span> { |
| <span class="ident">inner</span>: <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">clone</span>(), |
| <span class="ident">reseeder</span>: <span class="self">self</span>.<span class="ident">reseeder</span>.<span class="ident">clone</span>(), |
| <span class="ident">threshold</span>: <span class="self">self</span>.<span class="ident">threshold</span>, |
| <span class="ident">bytes_until_reseed</span>: <span class="number">0</span>, <span class="comment">// reseed clone on first use</span> |
| <span class="ident">fork_counter</span>: <span class="self">self</span>.<span class="ident">fork_counter</span>, |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> <span class="ident">CryptoRng</span> <span class="kw">for</span> <span class="ident">ReseedingCore</span><span class="op"><</span><span class="ident">R</span>, <span class="ident">Rsdr</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span> <span class="op">+</span> <span class="ident">CryptoRng</span>, |
| <span class="ident">Rsdr</span>: <span class="ident">RngCore</span> <span class="op">+</span> <span class="ident">CryptoRng</span>, |
| { |
| } |
| |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">unix</span>, <span class="ident">not</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"emscripten"</span>)))]</span> |
| <span class="kw">mod</span> <span class="ident">fork</span> { |
| <span class="kw">use</span> <span class="ident">core::sync::atomic</span>::{<span class="ident">AtomicUsize</span>, <span class="ident">Ordering</span>}; |
| <span class="kw">use</span> <span class="ident">std::sync::Once</span>; |
| |
| <span class="comment">// Fork protection</span> |
| <span class="comment">//</span> |
| <span class="comment">// We implement fork protection on Unix using `pthread_atfork`.</span> |
| <span class="comment">// When the process is forked, we increment `RESEEDING_RNG_FORK_COUNTER`.</span> |
| <span class="comment">// Every `ReseedingRng` stores the last known value of the static in</span> |
| <span class="comment">// `fork_counter`. If the cached `fork_counter` is less than</span> |
| <span class="comment">// `RESEEDING_RNG_FORK_COUNTER`, it is time to reseed this RNG.</span> |
| <span class="comment">//</span> |
| <span class="comment">// If reseeding fails, we don't deal with this by setting a delay, but just</span> |
| <span class="comment">// don't update `fork_counter`, so a reseed is attempted as soon as</span> |
| <span class="comment">// possible.</span> |
| |
| <span class="kw">static</span> <span class="ident">RESEEDING_RNG_FORK_COUNTER</span>: <span class="ident">AtomicUsize</span> <span class="op">=</span> <span class="ident">AtomicUsize::new</span>(<span class="number">0</span>); |
| |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">get_fork_counter</span>() -> <span class="ident">usize</span> { |
| <span class="ident">RESEEDING_RNG_FORK_COUNTER</span>.<span class="ident">load</span>(<span class="ident">Ordering::Relaxed</span>) |
| } |
| |
| <span class="kw">extern</span> <span class="string">"C"</span> <span class="kw">fn</span> <span class="ident">fork_handler</span>() { |
| <span class="comment">// Note: fetch_add is defined to wrap on overflow</span> |
| <span class="comment">// (which is what we want).</span> |
| <span class="ident">RESEEDING_RNG_FORK_COUNTER</span>.<span class="ident">fetch_add</span>(<span class="number">1</span>, <span class="ident">Ordering::Relaxed</span>); |
| } |
| |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">register_fork_handler</span>() { |
| <span class="kw">static</span> <span class="ident">REGISTER</span>: <span class="ident">Once</span> <span class="op">=</span> <span class="ident">Once::new</span>(); |
| <span class="ident">REGISTER</span>.<span class="ident">call_once</span>(<span class="op">|</span><span class="op">|</span> { |
| <span class="comment">// Bump the counter before and after forking (see #1169):</span> |
| <span class="kw">let</span> <span class="ident">ret</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="ident">libc::pthread_atfork</span>( |
| <span class="prelude-val">Some</span>(<span class="ident">fork_handler</span>), |
| <span class="prelude-val">Some</span>(<span class="ident">fork_handler</span>), |
| <span class="prelude-val">Some</span>(<span class="ident">fork_handler</span>), |
| ) }; |
| <span class="kw">if</span> <span class="ident">ret</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> { |
| <span class="macro">panic!</span>(<span class="string">"libc::pthread_atfork failed with code {}"</span>, <span class="ident">ret</span>); |
| } |
| }); |
| } |
| } |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">all</span>(<span class="ident">unix</span>, <span class="ident">not</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"emscripten"</span>))))]</span> |
| <span class="kw">mod</span> <span class="ident">fork</span> { |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">get_fork_counter</span>() -> <span class="ident">usize</span> { |
| <span class="number">0</span> |
| } |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">register_fork_handler</span>() {} |
| } |
| |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"std_rng"</span>)]</span> |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span> |
| <span class="kw">mod</span> <span class="ident">test</span> { |
| <span class="kw">use</span> <span class="ident"><span class="kw">super</span>::ReseedingRng</span>; |
| <span class="kw">use</span> <span class="ident"><span class="kw">crate</span>::rngs::mock::StepRng</span>; |
| <span class="kw">use</span> <span class="ident"><span class="kw">crate</span>::rngs::std::Core</span>; |
| <span class="kw">use</span> <span class="kw">crate</span>::{<span class="ident">Rng</span>, <span class="ident">SeedableRng</span>}; |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">test_reseeding</span>() { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">zero</span> <span class="op">=</span> <span class="ident">StepRng::new</span>(<span class="number">0</span>, <span class="number">0</span>); |
| <span class="kw">let</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident">Core::from_rng</span>(<span class="kw-2">&mut</span> <span class="ident">zero</span>).<span class="ident">unwrap</span>(); |
| <span class="kw">let</span> <span class="ident">thresh</span> <span class="op">=</span> <span class="number">1</span>; <span class="comment">// reseed every time the buffer is exhausted</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">reseeding</span> <span class="op">=</span> <span class="ident">ReseedingRng::new</span>(<span class="ident">rng</span>, <span class="ident">thresh</span>, <span class="ident">zero</span>); |
| |
| <span class="comment">// RNG buffer size is [u32; 64]</span> |
| <span class="comment">// Debug is only implemented up to length 32 so use two arrays</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buf</span> <span class="op">=</span> ([<span class="number">0u32</span>; <span class="number">32</span>], [<span class="number">0u32</span>; <span class="number">32</span>]); |
| <span class="ident">reseeding</span>.<span class="ident">fill</span>(<span class="kw-2">&mut</span> <span class="ident">buf</span>.<span class="number">0</span>); |
| <span class="ident">reseeding</span>.<span class="ident">fill</span>(<span class="kw-2">&mut</span> <span class="ident">buf</span>.<span class="number">1</span>); |
| <span class="kw">let</span> <span class="ident">seq</span> <span class="op">=</span> <span class="ident">buf</span>; |
| <span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="number">10</span> { |
| <span class="ident">reseeding</span>.<span class="ident">fill</span>(<span class="kw-2">&mut</span> <span class="ident">buf</span>.<span class="number">0</span>); |
| <span class="ident">reseeding</span>.<span class="ident">fill</span>(<span class="kw-2">&mut</span> <span class="ident">buf</span>.<span class="number">1</span>); |
| <span class="macro">assert_eq!</span>(<span class="ident">buf</span>, <span class="ident">seq</span>); |
| } |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">test_clone_reseeding</span>() { |
| <span class="attribute">#![<span class="ident">allow</span>(<span class="ident">clippy::redundant_clone</span>)]</span> |
| |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">zero</span> <span class="op">=</span> <span class="ident">StepRng::new</span>(<span class="number">0</span>, <span class="number">0</span>); |
| <span class="kw">let</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident">Core::from_rng</span>(<span class="kw-2">&mut</span> <span class="ident">zero</span>).<span class="ident">unwrap</span>(); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng1</span> <span class="op">=</span> <span class="ident">ReseedingRng::new</span>(<span class="ident">rng</span>, <span class="number">32</span> <span class="op">*</span> <span class="number">4</span>, <span class="ident">zero</span>); |
| |
| <span class="kw">let</span> <span class="ident">first</span>: <span class="ident">u32</span> <span class="op">=</span> <span class="ident">rng1</span>.<span class="ident">gen</span>(); |
| <span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="number">10</span> { |
| <span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">rng1</span>.<span class="ident">gen</span>::<span class="op"><</span><span class="ident">u32</span><span class="op">></span>(); |
| } |
| |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng2</span> <span class="op">=</span> <span class="ident">rng1</span>.<span class="ident">clone</span>(); |
| <span class="macro">assert_eq!</span>(<span class="ident">first</span>, <span class="ident">rng2</span>.<span class="ident">gen</span>::<span class="op"><</span><span class="ident">u32</span><span class="op">></span>()); |
| } |
| } |
| </code></pre></div> |
| </section><section id="search" class="content hidden"></section></div></main><div id="rustdoc-vars" data-root-path="../../../../" data-current-crate="rand" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.60.0-nightly (1bd4fdc94 2022-01-12)" ></div> |
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