EIP-1186 eth_getProof (#17737)

* first impl of eth_getProof

* fixed docu

* added comments and refactored based on comments from holiman

* created structs

* handle errors correctly

* change Value to *hexutil.Big in order to have the same output as parity

* use ProofList as return type

4 files changed, 105 insertions, 0 deletions

diff --git a/common/bytes.go b/common/bytes.go
index 0c257a1ee..c82e61624 100644
--- a/common/bytes.go
+++ b/common/bytes.go
@@ -31,6 +31,15 @@ func ToHex(b []byte) string {
 	return "0x" + hex
 }
 
+// ToHexArray creates a array of hex-string based on []byte
+func ToHexArray(b [][]byte) []string {
+	r := make([]string, len(b))
+	for i := range b {
+		r[i] = ToHex(b[i])
+	}
+	return r
+}
+
 // FromHex returns the bytes represented by the hexadecimal string s.
 // s may be prefixed with "0x".
 func FromHex(s string) []byte {
diff --git a/core/state/statedb.go b/core/state/statedb.go
index 216667ce9..b1bb53ed0 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -18,6 +18,7 @@
 package state
 
 import (
+	"errors"
 	"fmt"
 	"math/big"
 	"sort"
@@ -25,6 +26,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/rlp"
@@ -256,6 +258,24 @@ func (self *StateDB) GetState(addr common.Address, hash common.Hash) common.Hash
 	return common.Hash{}
 }
 
+// GetProof returns the MerkleProof for a given Account
+func (self *StateDB) GetProof(a common.Address) (vm.ProofList, error) {
+	var proof vm.ProofList
+	err := self.trie.Prove(crypto.Keccak256(a.Bytes()), 0, &proof)
+	return proof, err
+}
+
+// GetProof returns the StorageProof for given key
+func (self *StateDB) GetStorageProof(a common.Address, key common.Hash) (vm.ProofList, error) {
+	var proof vm.ProofList
+	trie := self.StorageTrie(a)
+	if trie == nil {
+		return proof, errors.New("storage trie for requested address does not exist")
+	}
+	err := trie.Prove(crypto.Keccak256(key.Bytes()), 0, &proof)
+	return proof, err
+}
+
 // GetCommittedState retrieves a value from the given account's committed storage trie.
 func (self *StateDB) GetCommittedState(addr common.Address, hash common.Hash) common.Hash {
 	stateObject := self.getStateObject(addr)
diff --git a/core/vm/interface.go b/core/vm/interface.go
index fc15082f1..1ae98cf7a 100644
--- a/core/vm/interface.go
+++ b/core/vm/interface.go
@@ -35,6 +35,8 @@ type StateDB interface {
 	SetNonce(common.Address, uint64)
 
 	GetCodeHash(common.Address) common.Hash
+	GetProof(common.Address) (ProofList, error)
+	GetStorageProof(common.Address, common.Hash) (ProofList, error)
 	GetCode(common.Address) []byte
 	SetCode(common.Address, []byte)
 	GetCodeSize(common.Address) int
@@ -78,3 +80,11 @@ type CallContext interface {
 	// Create a new contract
 	Create(env *EVM, me ContractRef, data []byte, gas, value *big.Int) ([]byte, common.Address, error)
 }
+
+// MerkleProof
+type ProofList [][]byte
+
+func (n *ProofList) Put(key []byte, value []byte) error {
+	*n = append(*n, value)
+	return nil
+}
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 196be43e0..0c751c328 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -508,6 +508,72 @@ func (s *PublicBlockChainAPI) GetBalance(ctx context.Context, address common.Add
 	return (*hexutil.Big)(state.GetBalance(address)), state.Error()
 }
 
+// Result structs for GetProof
+type AccountResult struct {
+	Address      common.Address  `json:"address"`
+	AccountProof []string        `json:"accountProof"`
+	Balance      *hexutil.Big    `json:"balance"`
+	CodeHash     common.Hash     `json:"codeHash"`
+	Nonce        hexutil.Uint64  `json:"nonce"`
+	StorageHash  common.Hash     `json:"storageHash"`
+	StorageProof []StorageResult `json:"storageProof"`
+}
+type StorageResult struct {
+	Key   string       `json:"key"`
+	Value *hexutil.Big `json:"value"`
+	Proof []string     `json:"proof"`
+}
+
+// GetProof returns the Merkle-proof for a given account and optionally some storage keys.
+func (s *PublicBlockChainAPI) GetProof(ctx context.Context, address common.Address, storageKeys []string, blockNr rpc.BlockNumber) (*AccountResult, error) {
+	state, _, err := s.b.StateAndHeaderByNumber(ctx, blockNr)
+	if state == nil || err != nil {
+		return nil, err
+	}
+
+	storageTrie := state.StorageTrie(address)
+	storageHash := types.EmptyRootHash
+	codeHash := state.GetCodeHash(address)
+	storageProof := make([]StorageResult, len(storageKeys))
+
+	// if we have a storageTrie, (which means the account exists), we can update the storagehash
+	if storageTrie != nil {
+		storageHash = storageTrie.Hash()
+	} else {
+		// no storageTrie means the account does not exist, so the codeHash is the hash of an empty bytearray.
+		codeHash = crypto.Keccak256Hash(nil)
+	}
+
+	// create the proof for the storageKeys
+	for i, key := range storageKeys {
+		if storageTrie != nil {
+			proof, storageError := state.GetStorageProof(address, common.HexToHash(key))
+			if storageError != nil {
+				return nil, storageError
+			}
+			storageProof[i] = StorageResult{key, (*hexutil.Big)(state.GetState(address, common.HexToHash(key)).Big()), common.ToHexArray(proof)}
+		} else {
+			storageProof[i] = StorageResult{key, &hexutil.Big{}, []string{}}
+		}
+	}
+
+	// create the accountProof
+	accountProof, proofErr := state.GetProof(address)
+	if proofErr != nil {
+		return nil, proofErr
+	}
+
+	return &AccountResult{
+		Address:      address,
+		AccountProof: common.ToHexArray(accountProof),
+		Balance:      (*hexutil.Big)(state.GetBalance(address)),
+		CodeHash:     codeHash,
+		Nonce:        hexutil.Uint64(state.GetNonce(address)),
+		StorageHash:  storageHash,
+		StorageProof: storageProof,
+	}, state.Error()
+}
+
 // GetBlockByNumber returns the requested block. When blockNr is -1 the chain head is returned. When fullTx is true all
 // transactions in the block are returned in full detail, otherwise only the transaction hash is returned.
 func (s *PublicBlockChainAPI) GetBlockByNumber(ctx context.Context, blockNr rpc.BlockNumber, fullTx bool) (map[string]interface{}, error) {