auto merge of #8174 : DaGenix/rust/digest-improvements, r=brson

Same content as #8097, but bors had an issue with that pull request. Opening a new one.

Author: bors

src/libextra/crypto/cryptoutil.rs

@@ -0,0 +1,327 @@
+// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::num::One;
+use std::vec::bytes::{MutableByteVector, copy_memory};
+
+
+/// Write a u64 into a vector, which must be 8 bytes long. The value is written in big-endian
+/// format.
+pub fn write_u64_be(dst: &mut[u8], input: u64) {
+    use std::cast::transmute;
+    use std::unstable::intrinsics::to_be64;
+    assert!(dst.len() == 8);
+    unsafe {
+        let x: *mut i64 = transmute(dst.unsafe_mut_ref(0));
+        *x = to_be64(input as i64);
+    }
+}
+
+/// Write a u32 into a vector, which must be 4 bytes long. The value is written in big-endian
+/// format.
+pub fn write_u32_be(dst: &mut[u8], input: u32) {
+    use std::cast::transmute;
+    use std::unstable::intrinsics::to_be32;
+    assert!(dst.len() == 4);
+    unsafe {
+        let x: *mut i32 = transmute(dst.unsafe_mut_ref(0));
+        *x = to_be32(input as i32);
+    }
+}
+
+/// Read a vector of bytes into a vector of u64s. The values are read in big-endian format.
+pub fn read_u64v_be(dst: &mut[u64], input: &[u8]) {
+    use std::cast::transmute;
+    use std::unstable::intrinsics::to_be64;
+    assert!(dst.len() * 8 == input.len());
+    unsafe {
+        let mut x: *mut i64 = transmute(dst.unsafe_mut_ref(0));
+        let mut y: *i64 = transmute(input.unsafe_ref(0));
+        do dst.len().times() {
+            *x = to_be64(*y);
+            x = x.offset(1);
+            y = y.offset(1);
+        }
+    }
+}
+
+/// Read a vector of bytes into a vector of u32s. The values are read in big-endian format.
+pub fn read_u32v_be(dst: &mut[u32], input: &[u8]) {
+    use std::cast::transmute;
+    use std::unstable::intrinsics::to_be32;
+    assert!(dst.len() * 4 == input.len());
+    unsafe {
+        let mut x: *mut i32 = transmute(dst.unsafe_mut_ref(0));
+        let mut y: *i32 = transmute(input.unsafe_ref(0));
+        do dst.len().times() {
+            *x = to_be32(*y);
+            x = x.offset(1);
+            y = y.offset(1);
+        }
+    }
+}
+
+
+/// Returns true if adding the two parameters will result in integer overflow
+pub fn will_add_overflow<T: Int + Unsigned>(x: T, y: T) -> bool {
+    // This doesn't handle negative values! Don't copy this code elsewhere without considering if
+    // negative values are important to you!
+    let max: T = Bounded::max_value();
+    return x > max - y;
+}
+
+/// Shifts the second parameter and then adds it to the first. fails!() if there would be unsigned
+/// integer overflow.
+pub fn shift_add_check_overflow<T: Int + Unsigned + Clone>(x: T, mut y: T, shift: T) -> T {
+    if y.leading_zeros() < shift {
+        fail!("Could not add values - integer overflow.");
+    }
+    y = y << shift;
+
+    if will_add_overflow(x.clone(), y.clone()) {
+        fail!("Could not add values - integer overflow.");
+    }
+
+    return x + y;
+}
+
+/// Shifts the second parameter and then adds it to the first, which is a tuple where the first
+/// element is the high order value. fails!() if there would be unsigned integer overflow.
+pub fn shift_add_check_overflow_tuple
+        <T: Int + Unsigned + Clone>
+        (x: (T, T), mut y: T, shift: T) -> (T, T) {
+    if y.leading_zeros() < shift {
+        fail!("Could not add values - integer overflow.");
+    }
+    y = y << shift;
+
+    match x {
+        (hi, low) => {
+            let one: T = One::one();
+            if will_add_overflow(low.clone(), y.clone()) {
+                if will_add_overflow(hi.clone(), one.clone()) {
+                    fail!("Could not add values - integer overflow.");
+                } else {
+                    return (hi + one, low + y);
+                }
+            } else {
+                return (hi, low + y);
+            }
+        }
+    }
+}
+
+
+/// A FixedBuffer, likes its name implies, is a fixed size buffer. When the buffer becomes full, it
+/// must be processed. The input() method takes care of processing and then clearing the buffer
+/// automatically. However, other methods do not and require the caller to process the buffer. Any
+/// method that modifies the buffer directory or provides the caller with bytes that can be modifies
+/// results in those bytes being marked as used by the buffer.
+pub trait FixedBuffer {
+    /// Input a vector of bytes. If the buffer becomes full, proccess it with the provided
+    /// function and then clear the buffer.
+    fn input(&mut self, input: &[u8], func: &fn(&[u8]));
+
+    /// Reset the buffer.
+    fn reset(&mut self);
+
+    /// Zero the buffer up until the specified index. The buffer position currently must not be
+    /// greater than that index.
+    fn zero_until(&mut self, idx: uint);
+
+    /// Get a slice of the buffer of the specified size. There must be at least that many bytes
+    /// remaining in the buffer.
+    fn next<'s>(&'s mut self, len: uint) -> &'s mut [u8];
+
+    /// Get the current buffer. The buffer must already be full. This clears the buffer as well.
+    fn full_buffer<'s>(&'s mut self) -> &'s [u8];
+
+    /// Get the current position of the buffer.
+    fn position(&self) -> uint;
+
+    /// Get the number of bytes remaining in the buffer until it is full.
+    fn remaining(&self) -> uint;
+
+    /// Get the size of the buffer
+    fn size(&self) -> uint;
+}
+
+macro_rules! impl_fixed_buffer( ($name:ident, $size:expr) => (
+    impl FixedBuffer for $name {
+        fn input(&mut self, input: &[u8], func: &fn(&[u8])) {
+            let mut i = 0;
+
+            // FIXME: #6304 - This local variable shouldn't be necessary.
+            let size = $size;
+
+            // If there is already data in the buffer, copy as much as we can into it and process
+            // the data if the buffer becomes full.
+            if self.buffer_idx != 0 {
+                let buffer_remaining = size - self.buffer_idx;
+                if input.len() >= buffer_remaining {
+                        copy_memory(
+                            self.buffer.mut_slice(self.buffer_idx, size),
+                            input.slice_to(buffer_remaining),
+                            buffer_remaining);
+                    self.buffer_idx = 0;
+                    func(self.buffer);
+                    i += buffer_remaining;
+                } else {
+                    copy_memory(
+                        self.buffer.mut_slice(self.buffer_idx, self.buffer_idx + input.len()),
+                        input,
+                        input.len());
+                    self.buffer_idx += input.len();
+                    return;
+                }
+            }
+
+            // While we have at least a full buffer size chunks's worth of data, process that data
+            // without copying it into the buffer
+            while input.len() - i >= size {
+                func(input.slice(i, i + size));
+                i += size;
+            }
+
+            // Copy any input data into the buffer. At this point in the method, the ammount of
+            // data left in the input vector will be less than the buffer size and the buffer will
+            // be empty.
+            let input_remaining = input.len() - i;
+            copy_memory(
+                self.buffer.mut_slice(0, input_remaining),
+                input.slice_from(i),
+                input.len() - i);
+            self.buffer_idx += input_remaining;
+        }
+
+        fn reset(&mut self) {
+            self.buffer_idx = 0;
+        }
+
+        fn zero_until(&mut self, idx: uint) {
+            assert!(idx >= self.buffer_idx);
+            self.buffer.mut_slice(self.buffer_idx, idx).set_memory(0);
+            self.buffer_idx = idx;
+        }
+
+        fn next<'s>(&'s mut self, len: uint) -> &'s mut [u8] {
+            self.buffer_idx += len;
+            return self.buffer.mut_slice(self.buffer_idx - len, self.buffer_idx);
+        }
+
+        fn full_buffer<'s>(&'s mut self) -> &'s [u8] {
+            assert!(self.buffer_idx == $size);
+            self.buffer_idx = 0;
+            return self.buffer.slice_to($size);
+        }
+
+        fn position(&self) -> uint { self.buffer_idx }
+
+        fn remaining(&self) -> uint { $size - self.buffer_idx }
+
+        fn size(&self) -> uint { $size }
+    }
+))
+
+
+/// A fixed size buffer of 64 bytes useful for cryptographic operations.
+pub struct FixedBuffer64 {
+    priv buffer: [u8, ..64],
+    priv buffer_idx: uint,
+}
+
+impl FixedBuffer64 {
+    /// Create a new buffer
+    pub fn new() -> FixedBuffer64 {
+        return FixedBuffer64 {
+            buffer: [0u8, ..64],
+            buffer_idx: 0
+        };
+    }
+}
+
+impl_fixed_buffer!(FixedBuffer64, 64)
+
+/// A fixed size buffer of 128 bytes useful for cryptographic operations.
+pub struct FixedBuffer128 {
+    priv buffer: [u8, ..128],
+    priv buffer_idx: uint,
+}
+
+impl FixedBuffer128 {
+    /// Create a new buffer
+    pub fn new() -> FixedBuffer128 {
+        return FixedBuffer128 {
+            buffer: [0u8, ..128],
+            buffer_idx: 0
+        };
+    }
+}
+
+impl_fixed_buffer!(FixedBuffer128, 128)
+
+
+/// The StandardPadding trait adds a method useful for various hash algorithms to a FixedBuffer
+/// struct.
+pub trait StandardPadding {
+    /// Add standard padding to the buffer. The buffer must not be full when this method is called
+    /// and is guaranteed to have exactly rem remaining bytes when it returns. If there are not at
+    /// least rem bytes available, the buffer will be zero padded, processed, cleared, and then
+    /// filled with zeros again until only rem bytes are remaining.
+    fn standard_padding(&mut self, rem: uint, func: &fn(&[u8]));
+}
+
+impl <T: FixedBuffer> StandardPadding for T {
+    fn standard_padding(&mut self, rem: uint, func: &fn(&[u8])) {
+        let size = self.size();
+
+        self.next(1)[0] = 128;
+
+        if self.remaining() < rem {
+            self.zero_until(size);
+            func(self.full_buffer());
+        }
+
+        self.zero_until(size - rem);
+    }
+}
+
+
+#[cfg(test)]
+mod test {
+    use std::rand::IsaacRng;
+    use std::rand::RngUtil;
+    use std::vec;
+
+    use digest::Digest;
+
+    /// Feed 1,000,000 'a's into the digest with varying input sizes and check that the result is
+    /// correct.
+    pub fn test_digest_1million_random<D: Digest>(digest: &mut D, blocksize: uint, expected: &str) {
+        let total_size = 1000000;
+        let buffer = vec::from_elem(blocksize * 2, 'a' as u8);
+        let mut rng = IsaacRng::new_unseeded();
+        let mut count = 0;
+
+        digest.reset();
+
+        while count < total_size {
+            let next: uint = rng.gen_uint_range(0, 2 * blocksize + 1);
+            let remaining = total_size - count;
+            let size = if next > remaining { remaining } else { next };
+            digest.input(buffer.slice_to(size));
+            count += size;
+        }
+
+        let result_str = digest.result_str();
+
+        assert!(expected == result_str);
+    }
+}