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