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// Copyright (c) 2016 Mark Lee
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//! Idiomatic Rust wrapper for `CommonCrypto`'s `CCDigestCtx` struct.
use commoncrypto_sys::{CCDigestCreate, CCDigestCtx, CCDigestDestroy, CCDigestFinal,
CCDigestGetOutputSizeFromRef, CCDigestReset, CCDigestUpdate};
use std::io;
pub use commoncrypto_sys::CCDigestAlgorithm;
const MAX_DIGEST_SIZE: usize = 64;
macro_rules! err_from_ccdigest_retval{
($func_name: expr, $val: expr) => {
Err(io::Error::new(io::ErrorKind::Other,
format!("{} returned nonzero: {}", $func_name, $val)))
}
}
#[derive(PartialEq, Copy, Clone, Debug)]
enum State {
Reset,
Updated,
Finalized,
}
/// Generates cryptographic hashes.
#[derive(Debug)]
pub struct Hasher {
ctx: *mut CCDigestCtx,
state: State,
}
impl Hasher {
/// Creates a new `Hasher` which will use the given cryptographic `algorithm`.
pub fn new(algorithm: CCDigestAlgorithm) -> Hasher {
let ctx: *mut CCDigestCtx;
unsafe {
ctx = CCDigestCreate(algorithm);
}
Hasher {
ctx: ctx,
state: State::Reset,
}
}
fn init(&mut self) {
match self.state {
State::Reset => return,
State::Updated => {
let _ = self.finish();
}
State::Finalized => (),
}
unsafe { CCDigestReset(self.ctx) };
self.state = State::Reset;
}
/// Feeds data into the hasher.
pub fn update(&mut self, data: &[u8]) -> io::Result<usize> {
if self.state == State::Finalized {
self.init();
}
let result = unsafe { CCDigestUpdate(self.ctx, data.as_ptr() as *mut _, data.len()) };
if result == 0 {
self.state = State::Updated;
Ok(data.len())
} else {
err_from_ccdigest_retval!("CCDigestCreate", result)
}
}
/// Finalizes digest operations and produces the digest output.
pub fn finish(&mut self) -> io::Result<Vec<u8>> {
if self.state == State::Finalized {
self.init();
}
let expected_len = unsafe { CCDigestGetOutputSizeFromRef(self.ctx) };
let mut md = vec![0; MAX_DIGEST_SIZE];
let result = unsafe { CCDigestFinal(self.ctx, md.as_mut_ptr()) };
if result == 0 {
self.state = State::Finalized;
md.truncate(expected_len);
Ok(md)
} else {
err_from_ccdigest_retval!("CCDigestFinal", result)
}
}
}
impl io::Write for Hasher {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.update(buf)
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl Drop for Hasher {
fn drop(&mut self) {
if self.state != State::Finalized {
let _ = self.finish();
}
unsafe { CCDigestDestroy(self.ctx) }
}
}
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