openethereum/util/src/bloom.rs

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// Copyright 2015, 2016 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
//! Bloom operations.
use std::mem;
use std::ops::DerefMut;
use {H64, H160, H256, H512, H520, H2048, FixedHash};
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/// Returns log2.
pub fn log2(x: usize) -> u32 {
if x <= 1 {
return 0;
}
let n = x.leading_zeros();
mem::size_of::<usize>() as u32 * 8 - n
}
/// Bloom operations.
pub trait Bloomable: Sized + Default + DerefMut<Target = [u8]> {
/// When interpreting self as a bloom output, augment (bit-wise OR) with the a bloomed version of `b`.
fn shift_bloomed<'a, T>(&'a mut self, b: &T) -> &'a mut Self where T: Bloomable;
/// Same as `shift_bloomed` except that `self` is consumed and a new value returned.
fn with_bloomed<T>(mut self, b: &T) -> Self where T: Bloomable {
self.shift_bloomed(b);
self
}
/// Construct new instance equal to the bloomed value of `b`.
fn from_bloomed<T>(b: &T) -> Self where T: Bloomable;
/// Bloom the current value using the bloom parameter `m`.
fn bloom_part<T>(&self, m: usize) -> T where T: Bloomable;
/// Check to see whether this hash, interpreted as a bloom, contains the value `b` when bloomed.
fn contains_bloomed<T>(&self, b: &T) -> bool where T: Bloomable;
}
macro_rules! impl_bloomable_for_hash {
($name: ident, $size: expr) => {
impl Bloomable for $name {
fn shift_bloomed<'a, T>(&'a mut self, b: &T) -> &'a mut Self where T: Bloomable {
let bp: Self = b.bloom_part($size);
let new_self = &bp | self;
self.0 = new_self.0;
self
}
fn bloom_part<T>(&self, m: usize) -> T where T: Bloomable + Default {
// numbers of bits
// TODO: move it to some constant
let p = 3;
let bloom_bits = m * 8;
let mask = bloom_bits - 1;
let bloom_bytes = (log2(bloom_bits) + 7) / 8;
// must be a power of 2
assert_eq!(m & (m - 1), 0);
// out of range
assert!(p * bloom_bytes <= $size);
// return type
let mut ret = T::default();
// 'ptr' to out slice
let mut ptr = 0;
// set p number of bits,
// p is equal 3 according to yellowpaper
for _ in 0..p {
let mut index = 0 as usize;
for _ in 0..bloom_bytes {
index = (index << 8) | self.0[ptr] as usize;
ptr += 1;
}
index &= mask;
ret[m - 1 - index / 8] |= 1 << (index % 8);
}
ret
}
fn contains_bloomed<T>(&self, b: &T) -> bool where T: Bloomable {
let bp: Self = b.bloom_part($size);
self.contains(&bp)
}
fn from_bloomed<T>(b: &T) -> Self where T: Bloomable {
b.bloom_part($size)
}
}
}
}
impl_bloomable_for_hash!(H64, 8);
impl_bloomable_for_hash!(H160, 20);
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impl_bloomable_for_hash!(H256, 32);
impl_bloomable_for_hash!(H512, 64);
impl_bloomable_for_hash!(H520, 65);
impl_bloomable_for_hash!(H2048, 256);
#[cfg(test)]
mod tests {
use {H160, H256, H2048};
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use sha3::Hashable;
use super::Bloomable;
#[test]
fn shift_bloomed() {
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let bloom: H2048 = "00000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002020000000000000000000000000000000000000000000008000000001000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000".into();
let address: H160 = "ef2d6d194084c2de36e0dabfce45d046b37d1106".into();
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let topic: H256 = "02c69be41d0b7e40352fc85be1cd65eb03d40ef8427a0ca4596b1ead9a00e9fc".into();
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let mut my_bloom = H2048::default();
assert!(!my_bloom.contains_bloomed(&address.sha3()));
assert!(!my_bloom.contains_bloomed(&topic.sha3()));
my_bloom.shift_bloomed(&address.sha3());
assert!(my_bloom.contains_bloomed(&address.sha3()));
assert!(!my_bloom.contains_bloomed(&topic.sha3()));
my_bloom.shift_bloomed(&topic.sha3());
assert_eq!(my_bloom, bloom);
assert!(my_bloom.contains_bloomed(&address.sha3()));
assert!(my_bloom.contains_bloomed(&topic.sha3()));
}
}