68 lines
1.8 KiB
Rust
68 lines
1.8 KiB
Rust
#![allow(unsafe_code)]
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#![allow(unused)]
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#[cfg(not(any(test, feature = "std", feature = "rand-custom-impl")))]
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compile_error!("None of the Cargo features `std` or `rand-custom-impl` is enabled. smoltcp needs a `rand` implementation to work. If your target supports `std`, enable the `std` feature to use the OS's RNG. Otherwise, you must enable the `rand-custom-impl` Cargo feature, and supply your own custom implementation using the `smoltcp::rand_custom_impl!()` macro");
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pub fn rand_u32() -> u32 {
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let mut val = [0; 4];
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rand_bytes(&mut val);
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u32::from_ne_bytes(val)
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}
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/// Fill `buf` with random bytes.
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pub fn rand_bytes(buf: &mut [u8]) {
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extern "Rust" {
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fn _smoltcp_rand(buf: &mut [u8]);
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}
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unsafe { _smoltcp_rand(buf) }
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}
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/// Methods required for a custom rand implementation.
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///
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/// This trait is not intended to be used directly, just to supply a custom rand implementation to smoltcp.
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#[cfg(feature = "rand-custom-impl")]
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pub trait Rand {
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/// Fill `buf` with random bytes.
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fn rand_bytes(buf: &mut [u8]);
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}
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/// Set the custom rand implementation.
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///
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/// # Example
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///
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/// ```
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/// struct Rand;
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/// smoltcp::rand_custom_impl!(Rand);
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/// impl smoltcp::Rand for Rand {
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/// fn rand_bytes(buf: &mut [u8]) {
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/// // TODO
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/// }
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/// }
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///
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#[macro_export]
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#[cfg(feature = "rand-custom-impl")]
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macro_rules! rand_custom_impl {
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($t: ty) => {
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#[no_mangle]
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fn _smoltcp_rand(buf: &mut [u8]) {
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<$t as $crate::Rand>::rand_bytes(buf)
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}
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};
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}
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#[cfg(all(feature = "std", not(feature = "rand-custom-impl"), not(test)))]
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#[no_mangle]
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fn _smoltcp_rand(buf: &mut [u8]) {
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use rand_core::RngCore;
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rand_core::OsRng.fill_bytes(buf)
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}
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#[cfg(test)]
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#[no_mangle]
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fn _smoltcp_rand(buf: &mut [u8]) {
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panic!("Rand should not be used when testing");
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}
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