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use io;
use mem;
use rand::Rng;
use sys::c;
pub struct OsRng {
hcryptprov: c::HCRYPTPROV
}
impl OsRng {
pub fn new() -> io::Result<OsRng> {
let mut hcp = 0;
let ret = unsafe {
c::CryptAcquireContextA(&mut hcp, 0 as c::LPCSTR, 0 as c::LPCSTR,
c::PROV_RSA_FULL,
c::CRYPT_VERIFYCONTEXT | c::CRYPT_SILENT)
};
if ret == 0 {
Err(io::Error::last_os_error())
} else {
Ok(OsRng { hcryptprov: hcp })
}
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
let mut v = [0; 4];
self.fill_bytes(&mut v);
unsafe { mem::transmute(v) }
}
fn next_u64(&mut self) -> u64 {
let mut v = [0; 8];
self.fill_bytes(&mut v);
unsafe { mem::transmute(v) }
}
fn fill_bytes(&mut self, v: &mut [u8]) {
for slice in v.chunks_mut(<c::DWORD>::max_value() as usize) {
let ret = unsafe {
c::CryptGenRandom(self.hcryptprov, slice.len() as c::DWORD,
slice.as_mut_ptr())
};
if ret == 0 {
panic!("couldn't generate random bytes: {}",
io::Error::last_os_error());
}
}
}
}
impl Drop for OsRng {
fn drop(&mut self) {
let ret = unsafe {
c::CryptReleaseContext(self.hcryptprov, 0)
};
if ret == 0 {
panic!("couldn't release context: {}",
io::Error::last_os_error());
}
}
}