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proof_iavl_absence.go
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proof_iavl_absence.go
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package iavl
import (
"fmt"
"github.com/pkg/errors"
"github.com/tendermint/tendermint/crypto/merkle"
)
const ProofOpIAVLAbsence = "iavl:a"
// IAVLAbsenceOp takes a key as its only argument
//
// If the produced root hash matches the expected hash, the proof
// is good.
type AbsenceOp struct {
// Encoded in ProofOp.Key.
key []byte
// To encode in ProofOp.Data.
// Proof is nil for an empty tree.
// The hash of an empty tree is nil.
Proof *RangeProof `json:"proof"`
}
var _ merkle.ProofOperator = AbsenceOp{}
func NewAbsenceOp(key []byte, proof *RangeProof) AbsenceOp {
return AbsenceOp{
key: key,
Proof: proof,
}
}
func AbsenceOpDecoder(pop merkle.ProofOp) (merkle.ProofOperator, error) {
if pop.Type != ProofOpIAVLAbsence {
return nil, errors.Errorf("unexpected ProofOp.Type; got %v, want %v", pop.Type, ProofOpIAVLAbsence)
}
var op AbsenceOp // a bit strange as we'll discard this, but it works.
err := cdc.UnmarshalBinaryLengthPrefixed(pop.Data, &op)
if err != nil {
return nil, errors.Wrap(err, "decoding ProofOp.Data into IAVLAbsenceOp")
}
return NewAbsenceOp(pop.Key, op.Proof), nil
}
func (op AbsenceOp) ProofOp() merkle.ProofOp {
bz := cdc.MustMarshalBinaryLengthPrefixed(op)
return merkle.ProofOp{
Type: ProofOpIAVLAbsence,
Key: op.key,
Data: bz,
}
}
func (op AbsenceOp) String() string {
return fmt.Sprintf("IAVLAbsenceOp{%v}", op.GetKey())
}
func (op AbsenceOp) Run(args [][]byte) ([][]byte, error) {
if len(args) != 0 {
return nil, errors.Errorf("expected 0 args, got %v", len(args))
}
// If the tree is nil, the proof is nil, and all keys are absent.
if op.Proof == nil {
return [][]byte{[]byte(nil)}, nil
}
// Compute the root hash and assume it is valid.
// The caller checks the ultimate root later.
root := op.Proof.ComputeRootHash()
err := op.Proof.Verify(root)
if err != nil {
return nil, errors.Wrap(err, "computing root hash")
}
// XXX What is the encoding for keys?
// We should decode the key depending on whether it's a string or hex,
// maybe based on quotes and 0x prefix?
err = op.Proof.VerifyAbsence(op.key)
if err != nil {
return nil, errors.Wrap(err, "verifying absence")
}
return [][]byte{root}, nil
}
func (op AbsenceOp) GetKey() []byte {
return op.key
}