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Merged
merged 4 commits into from
Feb 5, 2022
Merged

Enable support for espidf (esp32 family of microcontrollers) #245

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ed6438c
Support for the ESP-IDF framework
ivmarkov Nov 15, 2020
c3b02b8
Use esp_fill_random instead of libc::getrandom
thorhs Jan 30, 2022
6aaa41b
Updated documentation link for ESP32 target
thorhs Jan 30, 2022
4d49673
Removed misleading comment about optimization
thorhs Jan 30, 2022
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26 changes: 26 additions & 0 deletions src/espidf.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
// Copyright 2021 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.

//! Implementation for ESP-IDF
use crate::Error;
use core::ffi::c_void;

extern "C" {
fn esp_fill_random(buf: *mut c_void, len: usize) -> u32;
}

pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
// Not that NOT enabling WiFi, BT, or the voltage noise entropy source (via `bootloader_random_enable`)
// will cause ESP-IDF to return pseudo-random numbers based on the voltage noise entropy, after the initial boot process:
// https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/random.html
//
// However tracking if some of these entropy sources is enabled is way too difficult to implement here
unsafe { esp_fill_random(dest.as_mut_ptr().cast(), dest.len()) };

Ok(())
}
4 changes: 4 additions & 0 deletions src/lib.rs
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Expand Up @@ -27,6 +27,7 @@
//! | Hermit | `x86_64-*-hermit` | [`RDRAND`][18]
//! | SGX | `x86_64‑*‑sgx` | [RDRAND][18]
//! | VxWorks | `*‑wrs‑vxworks‑*` | `randABytes` after checking entropy pool initialization with `randSecure`
//! | ESP-IDF | `*‑espidf` | [`esp_fill_random()`][23]
//! | Emscripten | `*‑emscripten` | `/dev/random` (identical to `/dev/urandom`)
//! | WASI | `wasm32‑wasi` | [`random_get`][17]
//! | Web Browser | `wasm32‑*‑unknown` | [`Crypto.getRandomValues()`][14], see [WebAssembly support][16]
Expand Down Expand Up @@ -142,6 +143,7 @@
//! [20]: https://www.unix.com/man-page/mojave/4/random/
//! [21]: https://www.freebsd.org/cgi/man.cgi?query=getrandom&manpath=FreeBSD+12.0-stable
//! [22]: https://leaf.dragonflybsd.org/cgi/web-man?command=getrandom
//! [23]: https://docs.espressif.com/projects/esp-idf/en/release-v4.1/api-reference/system/system.html?highlight=esp_fill_random#_CPPv415esp_fill_randomPv6size_t

#![doc(
html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk.png",
Expand Down Expand Up @@ -209,6 +211,8 @@ cfg_if! {
#[path = "vxworks.rs"] mod imp;
} else if #[cfg(target_os = "solid_asp3")] {
#[path = "solid.rs"] mod imp;
} else if #[cfg(target_os = "espidf")] {
#[path = "espidf.rs"] mod imp;
} else if #[cfg(windows)] {
#[path = "windows.rs"] mod imp;
} else if #[cfg(all(target_arch = "x86_64", target_env = "sgx"))] {
Expand Down