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proof.go
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proof.go
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package iavl
import (
"bytes"
"fmt"
"github.com/pkg/errors"
"golang.org/x/crypto/ripemd160"
"github.com/tendermint/go-wire"
"github.com/tendermint/go-wire/data"
cmn "github.com/tendermint/tmlibs/common"
)
var (
// ErrInvalidProof is returned by Verify when a proof cannot be validated.
ErrInvalidProof = fmt.Errorf("invalid proof")
// ErrInvalidInputs is returned when the inputs passed to the function are invalid.
ErrInvalidInputs = fmt.Errorf("invalid inputs")
// ErrInvalidRoot is returned when the root passed in does not match the proof's.
ErrInvalidRoot = fmt.Errorf("invalid root")
// ErrNilRoot is returned when the root of the tree is nil.
ErrNilRoot = fmt.Errorf("tree root is nil")
)
type proofInnerNode struct {
Height int8
Size int
Left []byte
Right []byte
}
func (n *proofInnerNode) String() string {
return fmt.Sprintf("proofInnerNode[height=%d, %x / %x]", n.Height, n.Left, n.Right)
}
func (branch proofInnerNode) Hash(childHash []byte) []byte {
hasher := ripemd160.New()
buf := new(bytes.Buffer)
n, err := int(0), error(nil)
wire.WriteInt8(branch.Height, buf, &n, &err)
wire.WriteVarint(branch.Size, buf, &n, &err)
if len(branch.Left) == 0 {
wire.WriteByteSlice(childHash, buf, &n, &err)
wire.WriteByteSlice(branch.Right, buf, &n, &err)
} else {
wire.WriteByteSlice(branch.Left, buf, &n, &err)
wire.WriteByteSlice(childHash, buf, &n, &err)
}
if err != nil {
cmn.PanicCrisis(cmn.Fmt("Failed to hash proofInnerNode: %v", err))
}
hasher.Write(buf.Bytes())
return hasher.Sum(nil)
}
type proofLeafNode struct {
KeyBytes data.Bytes `json:"key"`
ValueBytes data.Bytes `json:"value"`
Version uint64 `json:"version"`
}
func (leaf proofLeafNode) Hash() []byte {
hasher := ripemd160.New()
buf := new(bytes.Buffer)
n, err := int(0), error(nil)
wire.WriteInt8(0, buf, &n, &err)
wire.WriteVarint(1, buf, &n, &err)
wire.WriteByteSlice(leaf.KeyBytes, buf, &n, &err)
wire.WriteByteSlice(leaf.ValueBytes, buf, &n, &err)
wire.WriteUint64(leaf.Version, buf, &n, &err)
if err != nil {
cmn.PanicCrisis(cmn.Fmt("Failed to hash proofLeafNode: %v", err))
}
hasher.Write(buf.Bytes())
return hasher.Sum(nil)
}
func (leaf proofLeafNode) isLesserThan(key []byte) bool {
return bytes.Compare(leaf.KeyBytes, key) == -1
}
func (leaf proofLeafNode) isGreaterThan(key []byte) bool {
return bytes.Compare(leaf.KeyBytes, key) == 1
}
func (node *Node) pathToKey(t *Tree, key []byte) (*PathToKey, *Node, error) {
path := &PathToKey{}
val, err := node._pathToKey(t, key, path)
return path, val, err
}
func (node *Node) _pathToKey(t *Tree, key []byte, path *PathToKey) (*Node, error) {
if node.height == 0 {
if bytes.Equal(node.key, key) {
return node, nil
}
return nil, errors.New("key does not exist")
}
if bytes.Compare(key, node.key) < 0 {
if n, err := node.getLeftNode(t)._pathToKey(t, key, path); err != nil {
return nil, err
} else {
branch := proofInnerNode{
Height: node.height,
Size: node.size,
Left: nil,
Right: node.getRightNode(t).hash,
}
path.InnerNodes = append(path.InnerNodes, branch)
return n, nil
}
}
if n, err := node.getRightNode(t)._pathToKey(t, key, path); err != nil {
return nil, err
} else {
branch := proofInnerNode{
Height: node.height,
Size: node.size,
Left: node.getLeftNode(t).hash,
Right: nil,
}
path.InnerNodes = append(path.InnerNodes, branch)
return n, nil
}
}
func (t *Tree) constructKeyAbsentProof(key []byte, proof *KeyAbsentProof) error {
// Get the index of the first key greater than the requested key, if the key doesn't exist.
idx, val := t.Get(key)
if val != nil {
return errors.Errorf("couldn't construct non-existence proof: key 0x%x exists", key)
}
var (
lkey, lval []byte
rkey, rval []byte
)
if idx > 0 {
lkey, lval = t.GetByIndex(idx - 1)
}
if idx <= t.Size()-1 {
rkey, rval = t.GetByIndex(idx)
}
if lkey == nil && rkey == nil {
return errors.New("couldn't get keys required for non-existence proof")
}
if lkey != nil {
path, node, _ := t.root.pathToKey(t, lkey)
proof.Left = &pathWithNode{
Path: path,
Node: proofLeafNode{lkey, lval, node.version},
}
}
if rkey != nil {
path, node, _ := t.root.pathToKey(t, rkey)
proof.Right = &pathWithNode{
Path: path,
Node: proofLeafNode{rkey, rval, node.version},
}
}
return nil
}
func (t *Tree) getWithProof(key []byte) (value []byte, proof *KeyExistsProof, err error) {
if t.root == nil {
return nil, nil, errors.WithStack(ErrNilRoot)
}
t.root.hashWithCount() // Ensure that all hashes are calculated.
path, node, err := t.root.pathToKey(t, key)
if err != nil {
return nil, nil, errors.Wrap(err, "could not construct path to key")
}
proof = &KeyExistsProof{
RootHash: t.root.hash,
PathToKey: path,
Version: node.version,
}
return node.value, proof, nil
}
func (t *Tree) keyAbsentProof(key []byte) (*KeyAbsentProof, error) {
if t.root == nil {
return nil, errors.WithStack(ErrNilRoot)
}
t.root.hashWithCount() // Ensure that all hashes are calculated.
proof := &KeyAbsentProof{
RootHash: t.root.hash,
Version: t.root.version,
}
if err := t.constructKeyAbsentProof(key, proof); err != nil {
return nil, errors.Wrap(err, "could not construct proof of non-existence")
}
return proof, nil
}