src/libstd/sys/windows/rand.rs

   1 // Copyright 2013-2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11
  12 use io;
  13 use mem;
  14 use rand::Rng;
  15 use sys::c;
  16
  17 pub struct OsRng {
  18     hcryptprov: c::HCRYPTPROV
  19 }
  20
  21 impl OsRng {
  22     /// Create a new `OsRng`.
  23     pub fn new() -> io::Result<OsRng> {
  24         let mut hcp = 0;
  25         let ret = unsafe {
  26             c::CryptAcquireContextA(&mut hcp, 0 as c::LPCSTR, 0 as c::LPCSTR,
  27                                     c::PROV_RSA_FULL,
  28                                     c::CRYPT_VERIFYCONTEXT | c::CRYPT_SILENT)
  29         };
  30
  31         if ret == 0 {
  32             Err(io::Error::last_os_error())
  33         } else {
  34             Ok(OsRng { hcryptprov: hcp })
  35         }
  36     }
  37 }
  38
  39 impl Rng for OsRng {
  40     fn next_u32(&mut self) -> u32 {
  41         let mut v = [0; 4];
  42         self.fill_bytes(&mut v);
  43         unsafe { mem::transmute(v) }
  44     }
  45     fn next_u64(&mut self) -> u64 {
  46         let mut v = [0; 8];
  47         self.fill_bytes(&mut v);
  48         unsafe { mem::transmute(v) }
  49     }
  50     fn fill_bytes(&mut self, v: &mut [u8]) {
  51         // CryptGenRandom takes a DWORD (u32) for the length so we need to
  52         // split up the buffer.
  53         for slice in v.chunks_mut(<c::DWORD>::max_value() as usize) {
  54             let ret = unsafe {
  55                 c::CryptGenRandom(self.hcryptprov, slice.len() as c::DWORD,
  56                                   slice.as_mut_ptr())
  57             };
  58             if ret == 0 {
  59                 panic!("couldn't generate random bytes: {}",
  60                        io::Error::last_os_error());
  61             }
  62         }
  63     }
  64 }
  65
  66 impl Drop for OsRng {
  67     fn drop(&mut self) {
  68         let ret = unsafe {
  69             c::CryptReleaseContext(self.hcryptprov, 0)
  70         };
  71         if ret == 0 {
  72             panic!("couldn't release context: {}",
  73                    io::Error::last_os_error());
  74         }
  75     }
  76 }