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
|
// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package trie
import (
"fmt"
"github.com/dexon-foundation/dexon/common"
"github.com/dexon-foundation/dexon/log"
)
// SecureTrie wraps a trie with key hashing. In a secure trie, all
// access operations hash the key using keccak256. This prevents
// calling code from creating long chains of nodes that
// increase the access time.
//
// Contrary to a regular trie, a SecureTrie can only be created with
// New and must have an attached database. The database also stores
// the preimage of each key.
//
// SecureTrie is not safe for concurrent use.
type SecureTrie struct {
trie Trie
hashKeyBuf [common.HashLength]byte
secKeyCache map[string][]byte
secKeyCacheOwner *SecureTrie // Pointer to self, replace the key cache on mismatch
}
// NewSecure creates a trie with an existing root node from a backing database
// and optional intermediate in-memory node pool.
//
// If root is the zero hash or the sha3 hash of an empty string, the
// trie is initially empty. Otherwise, New will panic if db is nil
// and returns MissingNodeError if the root node cannot be found.
//
// Accessing the trie loads nodes from the database or node pool on demand.
// Loaded nodes are kept around until their 'cache generation' expires.
// A new cache generation is created by each call to Commit.
// cachelimit sets the number of past cache generations to keep.
func NewSecure(root common.Hash, db *Database, cachelimit uint16) (*SecureTrie, error) {
if db == nil {
panic("trie.NewSecure called without a database")
}
trie, err := New(root, db)
if err != nil {
return nil, err
}
trie.SetCacheLimit(cachelimit)
return &SecureTrie{trie: *trie}, nil
}
// Get returns the value for key stored in the trie.
// The value bytes must not be modified by the caller.
func (t *SecureTrie) Get(key []byte) []byte {
res, err := t.TryGet(key)
if err != nil {
log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
}
return res
}
// TryGet returns the value for key stored in the trie.
// The value bytes must not be modified by the caller.
// If a node was not found in the database, a MissingNodeError is returned.
func (t *SecureTrie) TryGet(key []byte) ([]byte, error) {
return t.trie.TryGet(t.hashKey(key))
}
// Update associates key with value in the trie. Subsequent calls to
// Get will return value. If value has length zero, any existing value
// is deleted from the trie and calls to Get will return nil.
//
// The value bytes must not be modified by the caller while they are
// stored in the trie.
func (t *SecureTrie) Update(key, value []byte) {
if err := t.TryUpdate(key, value); err != nil {
log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
}
}
// TryUpdate associates key with value in the trie. Subsequent calls to
// Get will return value. If value has length zero, any existing value
// is deleted from the trie and calls to Get will return nil.
//
// The value bytes must not be modified by the caller while they are
// stored in the trie.
//
// If a node was not found in the database, a MissingNodeError is returned.
func (t *SecureTrie) TryUpdate(key, value []byte) error {
hk := t.hashKey(key)
err := t.trie.TryUpdate(hk, value)
if err != nil {
return err
}
t.getSecKeyCache()[string(hk)] = common.CopyBytes(key)
return nil
}
// Delete removes any existing value for key from the trie.
func (t *SecureTrie) Delete(key []byte) {
if err := t.TryDelete(key); err != nil {
log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
}
}
// TryDelete removes any existing value for key from the trie.
// If a node was not found in the database, a MissingNodeError is returned.
func (t *SecureTrie) TryDelete(key []byte) error {
hk := t.hashKey(key)
delete(t.getSecKeyCache(), string(hk))
return t.trie.TryDelete(hk)
}
// GetKey returns the sha3 preimage of a hashed key that was
// previously used to store a value.
func (t *SecureTrie) GetKey(shaKey []byte) []byte {
if key, ok := t.getSecKeyCache()[string(shaKey)]; ok {
return key
}
key, _ := t.trie.db.preimage(common.BytesToHash(shaKey))
return key
}
// Commit writes all nodes and the secure hash pre-images to the trie's database.
// Nodes are stored with their sha3 hash as the key.
//
// Committing flushes nodes from memory. Subsequent Get calls will load nodes
// from the database.
func (t *SecureTrie) Commit(onleaf LeafCallback) (root common.Hash, err error) {
// Write all the pre-images to the actual disk database
if len(t.getSecKeyCache()) > 0 {
t.trie.db.lock.Lock()
for hk, key := range t.secKeyCache {
t.trie.db.insertPreimage(common.BytesToHash([]byte(hk)), key)
}
t.trie.db.lock.Unlock()
t.secKeyCache = make(map[string][]byte)
}
// Commit the trie to its intermediate node database
return t.trie.Commit(onleaf)
}
// Hash returns the root hash of SecureTrie. It does not write to the
// database and can be used even if the trie doesn't have one.
func (t *SecureTrie) Hash() common.Hash {
return t.trie.Hash()
}
// Root returns the root hash of SecureTrie.
// Deprecated: use Hash instead.
func (t *SecureTrie) Root() []byte {
return t.trie.Root()
}
// Copy returns a copy of SecureTrie.
func (t *SecureTrie) Copy() *SecureTrie {
cpy := *t
return &cpy
}
// NodeIterator returns an iterator that returns nodes of the underlying trie. Iteration
// starts at the key after the given start key.
func (t *SecureTrie) NodeIterator(start []byte) NodeIterator {
return t.trie.NodeIterator(start)
}
// hashKey returns the hash of key as an ephemeral buffer.
// The caller must not hold onto the return value because it will become
// invalid on the next call to hashKey or secKey.
func (t *SecureTrie) hashKey(key []byte) []byte {
h := newHasher(0, 0, nil)
h.sha.Reset()
h.sha.Write(key)
buf := h.sha.Sum(t.hashKeyBuf[:0])
returnHasherToPool(h)
return buf
}
// getSecKeyCache returns the current secure key cache, creating a new one if
// ownership changed (i.e. the current secure trie is a copy of another owning
// the actual cache).
func (t *SecureTrie) getSecKeyCache() map[string][]byte {
if t != t.secKeyCacheOwner {
t.secKeyCacheOwner = t
t.secKeyCache = make(map[string][]byte)
}
return t.secKeyCache
}
|
