openethereum/src/triehash.rs

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//! Generete trie root
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use std::collections::BTreeMap;
use std::cmp;
use hash::*;
use sha3::*;
use rlp;
use rlp::RlpStream;
use vector::SharedPrefix;
/// Hex-prefix Notation. First nibble has flags: oddness = 2^0 & termination = 2^1.
///
/// The "termination marker" and "leaf-node" specifier are completely equivalent.
///
/// Input values are in range `[0, 0xf]`.
///
/// ```markdown
/// [0,0,1,2,3,4,5] 0x10012345 // 7 > 4
/// [0,1,2,3,4,5] 0x00012345 // 6 > 4
/// [1,2,3,4,5] 0x112345 // 5 > 3
/// [0,0,1,2,3,4] 0x00001234 // 6 > 3
/// [0,1,2,3,4] 0x101234 // 5 > 3
/// [1,2,3,4] 0x001234 // 4 > 3
/// [0,0,1,2,3,4,5,T] 0x30012345 // 7 > 4
/// [0,0,1,2,3,4,T] 0x20001234 // 6 > 4
/// [0,1,2,3,4,5,T] 0x20012345 // 6 > 4
/// [1,2,3,4,5,T] 0x312345 // 5 > 3
/// [1,2,3,4,T] 0x201234 // 4 > 3
/// ```
///
/// ```rust
/// extern crate ethcore_util as util;
/// use util::triehash::*;
///
/// fn main() {
/// let v = vec![0, 0, 1, 2, 3, 4, 5];
/// let e = vec![0x10, 0x01, 0x23, 0x45];
/// let h = hex_prefix_encode(&v, false);
/// assert_eq!(h, e);
///
/// let v = vec![0, 1, 2, 3, 4, 5];
/// let e = vec![0x00, 0x01, 0x23, 0x45];
/// let h = hex_prefix_encode(&v, false);
/// assert_eq!(h, e);
///
/// let v = vec![0, 1, 2, 3, 4, 5];
/// let e = vec![0x20, 0x01, 0x23, 0x45];
/// let h = hex_prefix_encode(&v, true);
/// assert_eq!(h, e);
///
/// let v = vec![1, 2, 3, 4, 5];
/// let e = vec![0x31, 0x23, 0x45];
/// let h = hex_prefix_encode(&v, true);
/// assert_eq!(h, e);
///
/// let v = vec![1, 2, 3, 4];
/// let e = vec![0x00, 0x12, 0x34];
/// let h = hex_prefix_encode(&v, false);
/// assert_eq!(h, e);
///
/// let v = vec![4, 1];
/// let e = vec![0x20, 0x41];
/// let h = hex_prefix_encode(&v, true);
/// assert_eq!(h, e);
/// }
/// ```
///
pub fn hex_prefix_encode(nibbles: &[u8], leaf: bool) -> Vec<u8> {
let inlen = nibbles.len();
let oddness_factor = inlen % 2;
// next even number divided by two
let reslen = (inlen + 2) >> 1;
let mut res = vec![];
res.reserve(reslen);
let first_byte = {
let mut bits = ((inlen as u8 & 1) + (2 * leaf as u8)) << 4;
if oddness_factor == 1 {
bits += nibbles[0];
}
bits
};
res.push(first_byte);
let mut offset = oddness_factor;
while offset < inlen {
let byte = (nibbles[offset] << 4) + nibbles[offset + 1];
res.push(byte);
offset += 2;
}
res
}
/// Converts slice of bytes to nibbles.
///
/// ```rust
/// extern crate ethcore_util as util;
/// use util::triehash::*;
///
/// fn main () {
/// let v = vec![0x31, 0x23, 0x45];
/// let e = vec![3, 1, 2, 3, 4, 5];
/// assert_eq!(as_nibbles(&v), e);
///
/// // A => 65 => 0x41 => [4, 1]
/// let v: Vec<u8> = From::from("A");
/// let e = vec![4, 1];
/// assert_eq!(as_nibbles(&v), e);
/// }
/// ```
pub fn as_nibbles(bytes: &[u8]) -> Vec<u8> {
let mut res = vec![];
res.reserve(bytes.len() * 2);
for i in 0..bytes.len() {
res.push(bytes[i] >> 4);
res.push((bytes[i] << 4) >> 4);
}
res
}
#[derive(Debug)]
pub struct NibblePair {
nibble: Vec<u8>,
data: Vec<u8>
}
impl NibblePair {
pub fn new(nibble: Vec<u8>, data: Vec<u8>) -> NibblePair {
NibblePair {
nibble: nibble,
data: data
}
}
pub fn new_raw(to_nibble: Vec<u8>, data: Vec<u8>) -> NibblePair {
NibblePair::new(as_nibbles(&to_nibble), data)
}
}
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fn nibble_shared_prefix_len(vec: &[NibblePair]) -> usize {
if vec.len() == 0 {
return 0;
}
vec.iter()
// skip first element
.skip(1)
// get minimum number of shared nibbles between first and each successive
.fold(vec[0].nibble.len(), | acc, pair | {
cmp::min(vec[0].nibble.shared_prefix_len(&pair.nibble), acc)
})
}
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pub fn ordered_trie_root(data: Vec<Vec<u8>>) -> H256 {
let vec: Vec<NibblePair> = data
// first put elements into btree to sort them by nibbles
// optimize it later
.into_iter()
.fold(BTreeMap::new(), | mut acc, vec | {
let len = acc.len();
acc.insert(as_nibbles(&rlp::encode(&len)), vec);
acc
})
// then move them to a vector
.into_iter()
.map(|(k, v)| NibblePair::new(k, v) )
.collect();
hash256(&vec)
}
pub fn hash256(vec: &[NibblePair]) -> H256 {
let out = match vec.len() {
0 => rlp::encode(&""),
_ => {
let mut stream = RlpStream::new();
hash256rlp(&vec, 0, &mut stream);
stream.out()
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}
};
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out.sha3()
}
fn hash256rlp(vec: &[NibblePair], pre_len: usize, stream: &mut RlpStream) {
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let vlen = vec.len();
// in case of empty slice, just append null
if vlen == 0 {
stream.append(&"");
return;
}
// if the slice contains just one item, append the suffix of the key
// and then append value
if vlen == 1 {
stream.append_list(2);
stream.append(&hex_prefix_encode(&vec[0].nibble[pre_len..], true));
stream.append(&vec[0].data);
return;
}
// get length of the longest shared prefix in slice keys
let shared_prefix = nibble_shared_prefix_len(vec);
// if shared prefix is higher than current prefix append its
// new part of the key to the stream
// then recursively append suffixes of all items who had this key
if shared_prefix > pre_len {
stream.append_list(2);
stream.append(&hex_prefix_encode(&vec[0].nibble[pre_len..shared_prefix], false));
hash256aux(vec, shared_prefix, stream);
return;
}
// an item for every possible nibble/suffix
// + 1 for data
stream.append_list(17);
// if first key len is equal to prefix_len, move to next element
let mut begin = match pre_len == vec[0].nibble.len() {
true => 1,
false => 0
};
// iterate over all possible nibbles
for i in 0..16 {
// cout how many successive elements have same next nibble
let len = vec[begin..].iter()
.map(| pair | pair.nibble[pre_len] )
.take_while(|&q| q == i).count();
// if at least 1 successive element has the same nibble
// append their suffixes
match len {
0 => { stream.append(&""); },
_ => hash256aux(&vec[begin..(begin + len)], pre_len + 1, stream)
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}
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begin += len;
}
// if fist key len is equal prefix, append it's value
match pre_len == vec[0].nibble.len() {
true => { stream.append(&vec[0].data); },
false => { stream.append(&""); }
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};
}
fn hash256aux(vec: &[NibblePair], pre_len: usize, stream: &mut RlpStream) {
let mut s = RlpStream::new();
hash256rlp(vec, pre_len, &mut s);
let out = s.out();
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match out.len() {
0...31 => stream.append_raw(&out, 1),
_ => stream.append(&out.sha3())
};
}
#[test]
fn test_shared_nibble_len() {
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let len = nibble_shared_prefix_len(&vec![
NibblePair::new(vec![0, 1, 2, 3, 4, 5, 6], vec![]),
NibblePair::new(vec![0, 1, 2, 3, 4, 5, 6], vec![]),
]);
assert_eq!(len , 7);
}
#[test]
fn test_shared_nibble_len2() {
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let len = nibble_shared_prefix_len(&vec![
NibblePair::new(vec![0, 1, 2, 3, 4, 5, 6], vec![]),
NibblePair::new(vec![0, 1, 2, 3, 4, 5, 6], vec![]),
NibblePair::new(vec![4, 1, 2, 3, 4, 5, 6], vec![])
]);
assert_eq!(len , 0);
}
#[test]
fn test_shared_nibble_len3() {
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let len = nibble_shared_prefix_len(&vec![
NibblePair::new(vec![0, 1, 2, 3, 4, 5, 6], vec![]),
NibblePair::new(vec![0, 1, 2, 3, 4, 5, 6], vec![]),
NibblePair::new(vec![0, 1, 2, 4, 4, 5, 6], vec![])
]);
assert_eq!(len , 3);
}
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#[cfg(test)]
mod tests {
use std::str::FromStr;
use rustc_serialize::hex::FromHex;
use hash::*;
use triehash::*;
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#[test]
fn empty_trie_root() {
assert_eq!(hash256(&vec![]), H256::from_str("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421").unwrap());
}
#[test]
fn single_trie_item() {
let v = vec![
NibblePair::new_raw(From::from("A"),
From::from("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"))
];
assert_eq!(hash256(&v), H256::from_str("d23786fb4a010da3ce639d66d5e904a11dbc02746d1ce25029e53290cabf28ab").unwrap());
}
#[test]
fn foo_trie_item() {
let v = vec![
NibblePair::new_raw(From::from("foo"),
From::from("bar")),
NibblePair::new_raw(From::from("food"),
From::from("bass"))
];
assert_eq!(hash256(&v), H256::from_str("17beaa1648bafa633cda809c90c04af50fc8aed3cb40d16efbddee6fdf63c4c3").unwrap());
}
#[test]
fn dogs_trie_item() {
let v = vec![
NibblePair::new_raw(From::from("doe"),
From::from("reindeer")),
NibblePair::new_raw(From::from("dog"),
From::from("puppy")),
NibblePair::new_raw(From::from("dogglesworth"),
From::from("cat")),
];
assert_eq!(hash256(&v), H256::from_str("8aad789dff2f538bca5d8ea56e8abe10f4c7ba3a5dea95fea4cd6e7c3a1168d3").unwrap());
}
#[test]
fn puppy_trie_items() {
let v = vec![
NibblePair::new_raw(From::from("do"),
From::from("verb")),
NibblePair::new_raw(From::from("dog"),
From::from("puppy")),
NibblePair::new_raw(From::from("doge"),
From::from("coin")),
NibblePair::new_raw(From::from("horse"),
From::from("stallion")),
];
assert_eq!(hash256(&v), H256::from_str("5991bb8c6514148a29db676a14ac506cd2cd5775ace63c30a4fe457715e9ac84").unwrap());
}
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#[test]
fn test_trie_root() {
let v = vec![
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NibblePair::new_raw("0000000000000000000000000000000000000000000000000000000000000045".from_hex().unwrap(),
"22b224a1420a802ab51d326e29fa98e34c4f24ea".from_hex().unwrap()),
NibblePair::new_raw("0000000000000000000000000000000000000000000000000000000000000046".from_hex().unwrap(),
"67706c2076330000000000000000000000000000000000000000000000000000".from_hex().unwrap()),
NibblePair::new_raw("000000000000000000000000697c7b8c961b56f675d570498424ac8de1a918f6".from_hex().unwrap(),
"6f6f6f6820736f2067726561742c207265616c6c6c793f000000000000000000".from_hex().unwrap()),
NibblePair::new_raw("0000000000000000000000007ef9e639e2733cb34e4dfc576d4b23f72db776b2".from_hex().unwrap(),
"4655474156000000000000000000000000000000000000000000000000000000".from_hex().unwrap()),
NibblePair::new_raw("000000000000000000000000ec4f34c97e43fbb2816cfd95e388353c7181dab1".from_hex().unwrap(),
"4e616d6552656700000000000000000000000000000000000000000000000000".from_hex().unwrap()),
NibblePair::new_raw("4655474156000000000000000000000000000000000000000000000000000000".from_hex().unwrap(),
"7ef9e639e2733cb34e4dfc576d4b23f72db776b2".from_hex().unwrap()),
NibblePair::new_raw("4e616d6552656700000000000000000000000000000000000000000000000000".from_hex().unwrap(),
"ec4f34c97e43fbb2816cfd95e388353c7181dab1".from_hex().unwrap()),
NibblePair::new_raw("6f6f6f6820736f2067726561742c207265616c6c6c793f000000000000000000".from_hex().unwrap(),
"697c7b8c961b56f675d570498424ac8de1a918f6".from_hex().unwrap())
];
let root = H256::from_str("9f6221ebb8efe7cff60a716ecb886e67dd042014be444669f0159d8e68b42100").unwrap();
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let res = hash256(&v);
assert_eq!(res, root);
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}
}