package merkle import ( "bytes" "fmt" "github.com/pkg/errors" "github.com/tendermint/tendermint/crypto/tmhash" ) const ProofOpSimpleValue = "simple:v" // SimpleValueOp takes a key and a single value as argument and // produces the root hash. The corresponding tree structure is // the SimpleMap tree. SimpleMap takes a Hasher, and currently // Tendermint uses aminoHasher. SimpleValueOp should support // the hash function as used in aminoHasher. TODO support // additional hash functions here as options/args to this // operator. // // If the produced root hash matches the expected hash, the // proof is good. type SimpleValueOp struct { // Encoded in ProofOp.Key. key []byte // To encode in ProofOp.Data Proof *SimpleProof `json:"simple_proof"` } var _ ProofOperator = SimpleValueOp{} func NewSimpleValueOp(key []byte, proof *SimpleProof) SimpleValueOp { return SimpleValueOp{ key: key, Proof: proof, } } func SimpleValueOpDecoder(pop ProofOp) (ProofOperator, error) { if pop.Type != ProofOpSimpleValue { return nil, errors.Errorf("unexpected ProofOp.Type; got %v, want %v", pop.Type, ProofOpSimpleValue) } var op SimpleValueOp // 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 SimpleValueOp") } return NewSimpleValueOp(pop.Key, op.Proof), nil } func (op SimpleValueOp) ProofOp() ProofOp { bz := cdc.MustMarshalBinaryLengthPrefixed(op) return ProofOp{ Type: ProofOpSimpleValue, Key: op.key, Data: bz, } } func (op SimpleValueOp) String() string { return fmt.Sprintf("SimpleValueOp{%v}", op.GetKey()) } func (op SimpleValueOp) Run(args [][]byte) ([][]byte, error) { if len(args) != 1 { return nil, errors.Errorf("expected 1 arg, got %v", len(args)) } value := args[0] hasher := tmhash.New() hasher.Write(value) // does not error vhash := hasher.Sum(nil) bz := new(bytes.Buffer) // Wrap to hash the KVPair. encodeByteSlice(bz, op.key) // does not error encodeByteSlice(bz, vhash) // does not error kvhash := leafHash(bz.Bytes()) if !bytes.Equal(kvhash, op.Proof.LeafHash) { return nil, errors.Errorf("leaf hash mismatch: want %X got %X", op.Proof.LeafHash, kvhash) } return [][]byte{ op.Proof.ComputeRootHash(), }, nil } func (op SimpleValueOp) GetKey() []byte { return op.key }