1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
use std::cmp::min;
use bit_vec::BitVec;
use chain::merkle_node_hash;
use primitives::hash::H256;
pub struct PartialMerkleTree {
pub tx_count: usize,
pub hashes: Vec<H256>,
pub flags: BitVec,
}
#[cfg(test)]
pub struct ParsedPartialMerkleTree {
pub root: H256,
pub hashes: Vec<H256>,
pub flags: BitVec,
}
pub fn build_partial_merkle_tree(tx_hashes: Vec<H256>, tx_matches: BitVec) -> PartialMerkleTree {
PartialMerkleTreeBuilder::build(tx_hashes, tx_matches)
}
#[cfg(test)]
pub fn parse_partial_merkle_tree(tree: PartialMerkleTree) -> Result<ParsedPartialMerkleTree, String> {
PartialMerkleTreeBuilder::parse(tree)
}
struct PartialMerkleTreeBuilder {
all_len: usize,
all_hashes: Vec<H256>,
all_matches: BitVec,
hashes: Vec<H256>,
matches: BitVec,
}
impl PartialMerkleTree {
pub fn new(tx_count:usize, hashes: Vec<H256>, flags: BitVec) -> Self {
PartialMerkleTree {
tx_count: tx_count,
hashes: hashes,
flags: flags,
}
}
}
#[cfg(test)]
impl ParsedPartialMerkleTree {
pub fn new(root: H256, hashes: Vec<H256>, flags: BitVec) -> Self {
ParsedPartialMerkleTree {
root: root,
hashes: hashes,
flags: flags,
}
}
}
impl PartialMerkleTreeBuilder {
pub fn build(all_hashes: Vec<H256>, all_matches: BitVec) -> PartialMerkleTree {
let mut partial_merkle_tree = PartialMerkleTreeBuilder {
all_len: all_hashes.len(),
all_hashes: all_hashes,
all_matches: all_matches,
hashes: Vec::new(),
matches: BitVec::new(),
};
partial_merkle_tree.build_tree();
PartialMerkleTree::new(partial_merkle_tree.all_len, partial_merkle_tree.hashes, partial_merkle_tree.matches)
}
#[cfg(test)]
pub fn parse(tree: PartialMerkleTree) -> Result<ParsedPartialMerkleTree, String> {
let mut partial_merkle_tree = PartialMerkleTreeBuilder {
all_len: tree.tx_count,
all_hashes: Vec::new(),
all_matches: BitVec::from_elem(tree.tx_count, false),
hashes: tree.hashes,
matches: tree.flags,
};
let merkle_root = try!(partial_merkle_tree.parse_tree());
Ok(ParsedPartialMerkleTree::new(merkle_root, partial_merkle_tree.all_hashes, partial_merkle_tree.all_matches))
}
fn build_tree(&mut self) {
let tree_height = self.tree_height();
self.build_branch(tree_height, 0)
}
#[cfg(test)]
fn parse_tree(&mut self) -> Result<H256, String> {
if self.all_len == 0 {
return Err("no transactions".into());
}
if self.hashes.len() > self.all_len {
return Err("too many hashes".into());
}
if self.matches.len() < self.hashes.len() {
return Err("too few matches".into());
}
let mut matches_used = 0usize;
let mut hashes_used = 0usize;
let tree_height = self.tree_height();
let merkle_root = try!(self.parse_branch(tree_height, 0, &mut matches_used, &mut hashes_used));
if matches_used != self.matches.len() {
return Err("not all matches used".into());
}
if hashes_used != self.hashes.len() {
return Err("not all hashes used".into());
}
Ok(merkle_root)
}
fn build_branch(&mut self, height: usize, pos: usize) {
let transactions_begin = pos << height;
let transactions_end = min(self.all_len, (pos + 1) << height);
let flag = (transactions_begin..transactions_end).any(|idx| self.all_matches[idx]);
self.matches.push(flag);
if height == 0 || !flag {
let hash = self.branch_hash(height, pos);
self.hashes.push(hash);
} else {
self.build_branch(height - 1, pos << 1);
if (pos << 1) + 1 < self.level_width(height - 1) {
self.build_branch(height - 1, (pos << 1) + 1);
}
}
}
#[cfg(test)]
fn parse_branch(&mut self, height: usize, pos: usize, matches_used: &mut usize, hashes_used: &mut usize) -> Result<H256, String> {
if *matches_used >= self.matches.len() {
return Err("all matches used".into());
}
let flag = self.matches[*matches_used];
*matches_used += 1;
if height == 0 || !flag {
if *hashes_used > self.hashes.len() {
return Err("all hashes used".into());
}
let ref hash = self.hashes[*hashes_used];
*hashes_used += 1;
if height == 0 && flag {
self.all_hashes.push(hash.clone());
self.all_matches.set(pos, true);
}
Ok(hash.clone())
} else {
let left = try!(self.parse_branch(height - 1, pos << 1, matches_used, hashes_used));
let has_right_child = (pos << 1) + 1 < self.level_width(height - 1);
let right = if has_right_child {
try!(self.parse_branch(height - 1, (pos << 1) + 1, matches_used, hashes_used))
} else {
left.clone()
};
if has_right_child && left == right {
Err("met same hash twice".into())
} else {
Ok(merkle_node_hash(&left, &right))
}
}
}
fn tree_height(&self) -> usize {
let mut height = 0usize;
while self.level_width(height) > 1 {
height += 1;
}
height
}
fn level_width(&self, height: usize) -> usize {
(self.all_len + (1 << height) - 1) >> height
}
fn branch_hash(&self, height: usize, pos: usize) -> H256 {
if height == 0 {
self.all_hashes[pos].clone()
} else {
let left = self.branch_hash(height - 1, pos << 1);
let right = if (pos << 1) + 1 < self.level_width(height - 1) {
self.branch_hash(height - 1, (pos << 1) + 1)
} else {
left.clone()
};
merkle_node_hash(&left, &right)
}
}
}
#[cfg(test)]
mod tests {
extern crate test_data;
use chain::{Transaction, merkle_root};
use primitives::hash::H256;
use super::{build_partial_merkle_tree, parse_partial_merkle_tree};
#[test]
fn test_build_merkle_block() {
use bit_vec::BitVec;
use rand::{Rng, SeedableRng, StdRng};
let rng_seed: &[_] = &[0, 0, 0, 0];
let mut rng: StdRng = SeedableRng::from_seed(rng_seed);
let tx_counts: Vec<usize> = vec![1, 4, 7, 17, 56, 100, 127, 256, 312, 513, 1000, 4095];
for tx_count in tx_counts {
let transactions: Vec<Transaction> = (0..tx_count).map(|n| test_data::TransactionBuilder::with_version(n as i32).into()).collect();
let hashes: Vec<_> = transactions.iter().map(|t| t.hash()).collect();
let merkle_root = merkle_root(&hashes);
for seed_tweak in 1..15 {
let mut matches: BitVec = BitVec::with_capacity(tx_count);
let mut matched_hashes: Vec<H256> = Vec::with_capacity(tx_count);
for i in 0usize..tx_count {
let is_match = (rng.gen::<u32>() & ((1 << (seed_tweak / 2)) - 1)) == 0;
matches.push(is_match);
if is_match {
matched_hashes.push(hashes[i].clone());
}
}
let partial_tree = build_partial_merkle_tree(hashes.clone(), matches.clone());
let parsed_tree = parse_partial_merkle_tree(partial_tree).expect("no error");
assert_eq!(matched_hashes, parsed_tree.hashes);
assert_eq!(matches, parsed_tree.flags);
assert_eq!(merkle_root, parsed_tree.root);
}
}
}
}