1 /* Copyright (c) 2023, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14 */
15
16 //! Getting random bytes.
17
18 use crate::{with_output_array, FfiMutSlice};
19
20 /// Fills `buf` with random bytes.
rand_bytes(buf: &mut [u8])21 pub fn rand_bytes(buf: &mut [u8]) {
22 // Safety: `RAND_bytes` writes exactly `buf.len()` bytes.
23 let ret = unsafe { bssl_sys::RAND_bytes(buf.as_mut_ffi_ptr(), buf.len()) };
24
25 // BoringSSL's `RAND_bytes` always succeeds returning 1, or crashes the
26 // address space if the PRNG can not provide random data.
27 debug_assert!(ret == 1);
28 }
29
30 /// Returns an array of random bytes.
rand_array<const N: usize>() -> [u8; N]31 pub fn rand_array<const N: usize>() -> [u8; N] {
32 unsafe {
33 with_output_array(|out, out_len| {
34 // Safety: `RAND_bytes` writes exactly `out_len` bytes, as required.
35 let ret = bssl_sys::RAND_bytes(out, out_len);
36 // BoringSSL RAND_bytes always succeeds returning 1, or crashes the
37 // address space if the PRNG can not provide random data.
38 debug_assert!(ret == 1);
39 })
40 }
41 }
42
43 #[cfg(test)]
44 mod tests {
45 use super::*;
46
47 #[test]
fill()48 fn fill() {
49 let mut buf = [0; 32];
50 rand_bytes(&mut buf);
51 }
52
53 #[test]
fill_empty()54 fn fill_empty() {
55 let mut buf = [];
56 rand_bytes(&mut buf);
57 }
58
59 #[test]
array()60 fn array() {
61 let _rand: [u8; 32] = rand_array();
62 }
63
64 #[test]
empty_array()65 fn empty_array() {
66 let _rand: [u8; 0] = rand_array();
67 }
68 }
69