forked from ethereum/go-ethereum
-
Notifications
You must be signed in to change notification settings - Fork 1
/
proof.go
153 lines (146 loc) · 4.73 KB
/
proof.go
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
// 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 (
"bytes"
"fmt"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rlp"
)
// Prove constructs a merkle proof for key. The result contains all encoded nodes
// on the path to the value at key. The value itself is also included in the last
// node and can be retrieved by verifying the proof.
//
// If the trie does not contain a value for key, the returned proof contains all
// nodes of the longest existing prefix of the key (at least the root node), ending
// with the node that proves the absence of the key.
func (t *Trie) Prove(key []byte, fromLevel uint, proofDb ethdb.Putter) error {
// Collect all nodes on the path to key.
key = keybytesToHex(key)
nodes := []node{}
tn := t.root
for len(key) > 0 && tn != nil {
switch n := tn.(type) {
case *shortNode:
if len(key) < len(n.Key) || !bytes.Equal(n.Key, key[:len(n.Key)]) {
// The trie doesn't contain the key.
tn = nil
} else {
tn = n.Val
key = key[len(n.Key):]
}
nodes = append(nodes, n)
case *fullNode:
tn = n.Children[key[0]]
key = key[1:]
nodes = append(nodes, n)
case hashNode:
var err error
tn, err = t.resolveHash(n, nil)
if err != nil {
log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
return err
}
default:
panic(fmt.Sprintf("%T: invalid node: %v", tn, tn))
}
}
hasher := newHasher(0, 0, nil)
for i, n := range nodes {
// Don't bother checking for errors here since hasher panics
// if encoding doesn't work and we're not writing to any database.
n, _, _ = hasher.hashChildren(n, nil)
hn, _ := hasher.store(n, nil, false)
if hash, ok := hn.(hashNode); ok || i == 0 {
// If the node's database encoding is a hash (or is the
// root node), it becomes a proof element.
if fromLevel > 0 {
fromLevel--
} else {
enc, _ := rlp.EncodeToBytes(n)
if !ok {
hash = crypto.Keccak256(enc)
}
proofDb.Put(hash, enc)
}
}
}
return nil
}
// Prove constructs a merkle proof for key. The result contains all encoded nodes
// on the path to the value at key. The value itself is also included in the last
// node and can be retrieved by verifying the proof.
//
// If the trie does not contain a value for key, the returned proof contains all
// nodes of the longest existing prefix of the key (at least the root node), ending
// with the node that proves the absence of the key.
func (t *SecureTrie) Prove(key []byte, fromLevel uint, proofDb ethdb.Putter) error {
return t.trie.Prove(key, fromLevel, proofDb)
}
// VerifyProof checks merkle proofs. The given proof must contain the value for
// key in a trie with the given root hash. VerifyProof returns an error if the
// proof contains invalid trie nodes or the wrong value.
func VerifyProof(rootHash common.Hash, key []byte, proofDb DatabaseReader) (value []byte, nodes int, err error) {
key = keybytesToHex(key)
wantHash := rootHash
for i := 0; ; i++ {
buf, _ := proofDb.Get(wantHash[:])
if buf == nil {
return nil, i, fmt.Errorf("proof node %d (hash %064x) missing", i, wantHash)
}
n, err := decodeNode(wantHash[:], buf, 0)
if err != nil {
return nil, i, fmt.Errorf("bad proof node %d: %v", i, err)
}
keyrest, cld := get(n, key)
switch cld := cld.(type) {
case nil:
// The trie doesn't contain the key.
return nil, i, nil
case hashNode:
key = keyrest
copy(wantHash[:], cld)
case valueNode:
return cld, i + 1, nil
}
}
}
func get(tn node, key []byte) ([]byte, node) {
for {
switch n := tn.(type) {
case *shortNode:
if len(key) < len(n.Key) || !bytes.Equal(n.Key, key[:len(n.Key)]) {
return nil, nil
}
tn = n.Val
key = key[len(n.Key):]
case *fullNode:
tn = n.Children[key[0]]
key = key[1:]
case hashNode:
return key, n
case nil:
return key, nil
case valueNode:
return nil, n
default:
panic(fmt.Sprintf("%T: invalid node: %v", tn, tn))
}
}
}