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        if f.read_exact(buf).is_ok() {
9            return;
10        }
11    }
12    
13    // Fallback: LCG generator using system time as seed
14    use std::time::SystemTime;
15    let mut seed = SystemTime::now()
16        .duration_since(SystemTime::UNIX_EPOCH)
17        .map(|d| d.as_nanos() as u64)
18        .unwrap_or(0xFEEDFACE_DEADC0DE);
19        
20    for byte in buf.iter_mut() {
21        seed = seed.wrapping_mul(6364136223846793005).wrapping_add(1442695040888963407);
22        *byte = (seed >> 56) as u8;
23    }
24}
25
26/// Generate a random alphanumeric string of the specified length.
27pub fn random_alphanumeric(length: usize) -> String {
28    const CHARS: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
29    let mut bytes = vec![0u8; length];
30    fill_bytes(&mut bytes);
31    let mut s = String::with_capacity(length);
32    for b in bytes {
33        let idx = (b as usize) % CHARS.len();
34        s.push(CHARS[idx] as char);
35    }
36    s
37}
38
39/// Custom random number generator struct for backward compatibility
40#[derive(Clone, Copy, Debug)]
41pub struct CustomRng;
42
43impl CustomRng {
44    pub fn fill_bytes(&self, buf: &mut [u8]) {
45        fill_bytes(buf);
46    }
47}
48
49pub fn rng() -> CustomRng {
50    CustomRng
51}
52
53pub mod distr {
54    pub struct Alphanumeric;
55
56    pub trait SampleString {
57        fn sample_string(&self, rng: &mut super::CustomRng, length: usize) -> String;
58    }
59
60    impl SampleString for Alphanumeric {
61        fn sample_string(&self, _rng: &mut super::CustomRng, length: usize) -> String {
62            super::random_alphanumeric(length)
63        }
64    }
65}
rustbasic_core/rand.rs

rustbasic_core/
rand.rs
