neoneo-go/pkg/core/mpt/proof.go

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package mpt
import (
"bytes"
"errors"
"github.com/nspcc-dev/neo-go/pkg/core/storage"
"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/util/slice"
)
// GetProof returns a proof that key belongs to t.
// Proof consist of serialized nodes occurring on path from the root to the leaf of key.
func (t *Trie) GetProof(key []byte) ([][]byte, error) {
var proof [][]byte
if len(key) > MaxKeyLength {
return nil, errors.New("key is too big")
}
path := toNibbles(key)
r, err := t.getProof(t.root, path, &proof)
if err != nil {
return proof, err
}
t.root = r
return proof, nil
}
func (t *Trie) getProof(curr Node, path []byte, proofs *[][]byte) (Node, error) {
switch n := curr.(type) {
case *LeafNode:
if len(path) == 0 {
*proofs = append(*proofs, slice.Copy(n.Bytes()))
return n, nil
}
case *BranchNode:
*proofs = append(*proofs, slice.Copy(n.Bytes()))
i, path := splitPath(path)
r, err := t.getProof(n.Children[i], path, proofs)
if err != nil {
return nil, err
}
n.Children[i] = r
return n, nil
case *ExtensionNode:
if bytes.HasPrefix(path, n.key) {
*proofs = append(*proofs, slice.Copy(n.Bytes()))
r, err := t.getProof(n.next, path[len(n.key):], proofs)
if err != nil {
return nil, err
}
n.next = r
return n, nil
}
case *HashNode:
r, err := t.getFromStore(n.Hash())
if err != nil {
return nil, err
}
return t.getProof(r, path, proofs)
}
return nil, ErrNotFound
}
// VerifyProof verifies that path indeed belongs to a MPT with the specified root hash.
// It also returns value for the key.
func VerifyProof(rh util.Uint256, key []byte, proofs [][]byte) ([]byte, bool) {
path := toNibbles(key)
tr := NewTrie(NewHashNode(rh), false, storage.NewMemCachedStore(storage.NewMemoryStore()))
for i := range proofs {
h := hash.DoubleSha256(proofs[i])
// no errors in Put to memory store
_ = tr.Store.Put(makeStorageKey(h[:]), proofs[i])
}
_, leaf, _, err := tr.getWithPath(tr.root, path, true)
if err != nil {
return nil, false
}
return slice.Copy(leaf.(*LeafNode).value), true
}