rustbasic_core/
rand.rs

1use std::fs::File;
2use std::io::Read;
3
4/// Fill the buffer with cryptographically secure random bytes from /dev/urandom.
5/// If unavailable (e.g. non-Unix sandbox), fall back to a system-time-seeded LCG generator.
6pub fn fill_bytes(buf: &mut [u8]) {
7    if let Ok(mut f) = File::open("/dev/urandom")
8        && f.read_exact(buf).is_ok() {
9            return;
10        }
11    
12    // Fallback: LCG generator using system time as seed
13    use std::time::SystemTime;
14    let mut seed = SystemTime::now()
15        .duration_since(SystemTime::UNIX_EPOCH)
16        .map(|d| d.as_nanos() as u64)
17        .unwrap_or(0xFEEDFACE_DEADC0DE);
18        
19    for byte in buf.iter_mut() {
20        seed = seed.wrapping_mul(6364136223846793005).wrapping_add(1442695040888963407);
21        *byte = (seed >> 56) as u8;
22    }
23}
24
25/// Generate a random alphanumeric string of the specified length.
26pub fn random_alphanumeric(length: usize) -> String {
27    const CHARS: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
28    let mut bytes = vec![0u8; length];
29    fill_bytes(&mut bytes);
30    let mut s = String::with_capacity(length);
31    for b in bytes {
32        let idx = (b as usize) % CHARS.len();
33        s.push(CHARS[idx] as char);
34    }
35    s
36}
37
38/// Custom random number generator struct for backward compatibility
39#[derive(Clone, Copy, Debug)]
40pub struct CustomRng;
41
42impl CustomRng {
43    pub fn fill_bytes(&self, buf: &mut [u8]) {
44        fill_bytes(buf);
45    }
46}
47
48pub fn rng() -> CustomRng {
49    CustomRng
50}
51
52pub mod distr {
53    pub struct Alphanumeric;
54
55    pub trait SampleString {
56        fn sample_string(&self, rng: &mut super::CustomRng, length: usize) -> String;
57    }
58
59    impl SampleString for Alphanumeric {
60        fn sample_string(&self, _rng: &mut super::CustomRng, length: usize) -> String {
61            super::random_alphanumeric(length)
62        }
63    }
64}
rustbasic_core/rand.rs

rustbasic_core/
rand.rs
