Merge pull request #62 from ava-labs/devv0.3.15

Dev

2 files changed, 645 insertions, 0 deletions

diff --git a/ethclient/ethclient.go b/ethclient/ethclient.go
new file mode 100644
index 0000000..6dd4df8
--- /dev/null
+++ b/ethclient/ethclient.go
@@ -0,0 +1,586 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package ethclient provides a client for the Ethereum RPC API.
+package ethclient
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"math/big"
+
+	"github.com/ava-labs/avalanchego/ids"
+	"github.com/ava-labs/coreth"
+	"github.com/ava-labs/coreth/core/types"
+	"github.com/ava-labs/coreth/rpc"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+// Client defines typed wrappers for the Ethereum RPC API.
+type Client struct {
+	c *rpc.Client
+}
+
+// Dial connects a client to the given URL.
+func Dial(rawurl string) (*Client, error) {
+	return DialContext(context.Background(), rawurl)
+}
+
+func DialContext(ctx context.Context, rawurl string) (*Client, error) {
+	c, err := rpc.DialContext(ctx, rawurl)
+	if err != nil {
+		return nil, err
+	}
+	return NewClient(c), nil
+}
+
+// NewClient creates a client that uses the given RPC client.
+func NewClient(c *rpc.Client) *Client {
+	return &Client{c}
+}
+
+func (ec *Client) Close() {
+	ec.c.Close()
+}
+
+// Blockchain Access
+
+// ChainId retrieves the current chain ID for transaction replay protection.
+func (ec *Client) ChainID(ctx context.Context) (*big.Int, error) {
+	var result hexutil.Big
+	err := ec.c.CallContext(ctx, &result, "eth_chainId")
+	if err != nil {
+		return nil, err
+	}
+	return (*big.Int)(&result), err
+}
+
+// BlockByHash returns the given full block.
+//
+// Note that loading full blocks requires two requests. Use HeaderByHash
+// if you don't need all transactions or uncle headers.
+func (ec *Client) BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error) {
+	return ec.getBlock(ctx, "eth_getBlockByHash", hash, true)
+}
+
+// BlockByNumber returns a block from the current canonical chain. If number is nil, the
+// latest known block is returned.
+//
+// Note that loading full blocks requires two requests. Use HeaderByNumber
+// if you don't need all transactions or uncle headers.
+func (ec *Client) BlockByNumber(ctx context.Context, number *big.Int) (*types.Block, error) {
+	return ec.getBlock(ctx, "eth_getBlockByNumber", toBlockNumArg(number), true)
+}
+
+// BlockNumber returns the most recent block number
+func (ec *Client) BlockNumber(ctx context.Context) (uint64, error) {
+	var result hexutil.Uint64
+	err := ec.c.CallContext(ctx, &result, "eth_blockNumber")
+	return uint64(result), err
+}
+
+type rpcBlock struct {
+	Hash           common.Hash      `json:"hash"`
+	Transactions   []rpcTransaction `json:"transactions"`
+	UncleHashes    []common.Hash    `json:"uncles"`
+	Version        uint32           `json:"version"`
+	BlockExtraData string           `json:"blockExtraData"`
+}
+
+func (ec *Client) getBlock(ctx context.Context, method string, args ...interface{}) (*types.Block, error) {
+	var raw json.RawMessage
+	err := ec.c.CallContext(ctx, &raw, method, args...)
+	if err != nil {
+		return nil, err
+	} else if len(raw) == 0 {
+		return nil, coreth.NotFound
+	}
+	// Decode header and transactions.
+	var head *types.Header
+	var body rpcBlock
+	if err := json.Unmarshal(raw, &head); err != nil {
+		return nil, err
+	}
+	if err := json.Unmarshal(raw, &body); err != nil {
+		return nil, err
+	}
+
+	var blockExtraData *[]byte
+	if len(body.BlockExtraData) != 0 {
+		blockExtraDataDecoded, err := hexutil.Decode(body.BlockExtraData)
+		if err != nil {
+			return nil, fmt.Errorf("problem parsing block extra data: %w", err)
+		}
+		blockExtraData = &blockExtraDataDecoded
+	}
+
+	// Quick-verify transaction and uncle lists. This mostly helps with debugging the server.
+	if head.UncleHash == types.EmptyUncleHash && len(body.UncleHashes) > 0 {
+		return nil, fmt.Errorf("server returned non-empty uncle list but block header indicates no uncles")
+	}
+	if head.UncleHash != types.EmptyUncleHash && len(body.UncleHashes) == 0 {
+		return nil, fmt.Errorf("server returned empty uncle list but block header indicates uncles")
+	}
+	if head.TxHash == types.EmptyRootHash && len(body.Transactions) > 0 {
+		return nil, fmt.Errorf("server returned non-empty transaction list but block header indicates no transactions")
+	}
+	if head.TxHash != types.EmptyRootHash && len(body.Transactions) == 0 {
+		return nil, fmt.Errorf("server returned empty transaction list but block header indicates transactions")
+	}
+	// Load uncles because they are not included in the block response.
+	var uncles []*types.Header
+	if len(body.UncleHashes) > 0 {
+		uncles = make([]*types.Header, len(body.UncleHashes))
+		reqs := make([]rpc.BatchElem, len(body.UncleHashes))
+		for i := range reqs {
+			reqs[i] = rpc.BatchElem{
+				Method: "eth_getUncleByBlockHashAndIndex",
+				Args:   []interface{}{body.Hash, hexutil.EncodeUint64(uint64(i))},
+				Result: &uncles[i],
+			}
+		}
+		if err := ec.c.BatchCallContext(ctx, reqs); err != nil {
+			return nil, err
+		}
+		for i := range reqs {
+			if reqs[i].Error != nil {
+				return nil, reqs[i].Error
+			}
+			if uncles[i] == nil {
+				return nil, fmt.Errorf("got null header for uncle %d of block %x", i, body.Hash[:])
+			}
+		}
+	}
+	// Fill the sender cache of transactions in the block.
+	txs := make([]*types.Transaction, len(body.Transactions))
+	for i, tx := range body.Transactions {
+		if tx.From != nil {
+			setSenderFromServer(tx.tx, *tx.From, body.Hash)
+		}
+		txs[i] = tx.tx
+	}
+	return types.NewBlockWithHeader(head).WithBody(txs, uncles, body.Version, blockExtraData), nil
+}
+
+// HeaderByHash returns the block header with the given hash.
+func (ec *Client) HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error) {
+	var head *types.Header
+	err := ec.c.CallContext(ctx, &head, "eth_getBlockByHash", hash, false)
+	if err == nil && head == nil {
+		err = coreth.NotFound
+	}
+	return head, err
+}
+
+// HeaderByNumber returns a block header from the current canonical chain. If number is
+// nil, the latest known header is returned.
+func (ec *Client) HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error) {
+	var head *types.Header
+	err := ec.c.CallContext(ctx, &head, "eth_getBlockByNumber", toBlockNumArg(number), false)
+	if err == nil && head == nil {
+		err = coreth.NotFound
+	}
+	return head, err
+}
+
+type rpcTransaction struct {
+	tx *types.Transaction
+	txExtraInfo
+}
+
+type txExtraInfo struct {
+	BlockNumber *string         `json:"blockNumber,omitempty"`
+	BlockHash   *common.Hash    `json:"blockHash,omitempty"`
+	From        *common.Address `json:"from,omitempty"`
+}
+
+func (tx *rpcTransaction) UnmarshalJSON(msg []byte) error {
+	if err := json.Unmarshal(msg, &tx.tx); err != nil {
+		return err
+	}
+	return json.Unmarshal(msg, &tx.txExtraInfo)
+}
+
+// TransactionByHash returns the transaction with the given hash.
+func (ec *Client) TransactionByHash(ctx context.Context, hash common.Hash) (tx *types.Transaction, isPending bool, err error) {
+	var json *rpcTransaction
+	err = ec.c.CallContext(ctx, &json, "eth_getTransactionByHash", hash)
+	if err != nil {
+		return nil, false, err
+	} else if json == nil {
+		return nil, false, coreth.NotFound
+	} else if _, r, _ := json.tx.RawSignatureValues(); r == nil {
+		return nil, false, fmt.Errorf("server returned transaction without signature")
+	}
+	if json.From != nil && json.BlockHash != nil {
+		setSenderFromServer(json.tx, *json.From, *json.BlockHash)
+	}
+	return json.tx, json.BlockNumber == nil, nil
+}
+
+// TransactionSender returns the sender address of the given transaction. The transaction
+// must be known to the remote node and included in the blockchain at the given block and
+// index. The sender is the one derived by the protocol at the time of inclusion.
+//
+// There is a fast-path for transactions retrieved by TransactionByHash and
+// TransactionInBlock. Getting their sender address can be done without an RPC interaction.
+func (ec *Client) TransactionSender(ctx context.Context, tx *types.Transaction, block common.Hash, index uint) (common.Address, error) {
+	// Try to load the address from the cache.
+	sender, err := types.Sender(&senderFromServer{blockhash: block}, tx)
+	if err == nil {
+		return sender, nil
+	}
+	var meta struct {
+		Hash common.Hash
+		From common.Address
+	}
+	if err = ec.c.CallContext(ctx, &meta, "eth_getTransactionByBlockHashAndIndex", block, hexutil.Uint64(index)); err != nil {
+		return common.Address{}, err
+	}
+	if meta.Hash == (common.Hash{}) || meta.Hash != tx.Hash() {
+		return common.Address{}, errors.New("wrong inclusion block/index")
+	}
+	return meta.From, nil
+}
+
+// TransactionCount returns the total number of transactions in the given block.
+func (ec *Client) TransactionCount(ctx context.Context, blockHash common.Hash) (uint, error) {
+	var num hexutil.Uint
+	err := ec.c.CallContext(ctx, &num, "eth_getBlockTransactionCountByHash", blockHash)
+	return uint(num), err
+}
+
+// TransactionInBlock returns a single transaction at index in the given block.
+func (ec *Client) TransactionInBlock(ctx context.Context, blockHash common.Hash, index uint) (*types.Transaction, error) {
+	var json *rpcTransaction
+	err := ec.c.CallContext(ctx, &json, "eth_getTransactionByBlockHashAndIndex", blockHash, hexutil.Uint64(index))
+	if err != nil {
+		return nil, err
+	}
+	if json == nil {
+		return nil, coreth.NotFound
+	} else if _, r, _ := json.tx.RawSignatureValues(); r == nil {
+		return nil, fmt.Errorf("server returned transaction without signature")
+	}
+	if json.From != nil && json.BlockHash != nil {
+		setSenderFromServer(json.tx, *json.From, *json.BlockHash)
+	}
+	return json.tx, err
+}
+
+// TransactionReceipt returns the receipt of a transaction by transaction hash.
+// Note that the receipt is not available for pending transactions.
+func (ec *Client) TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
+	var r *types.Receipt
+	err := ec.c.CallContext(ctx, &r, "eth_getTransactionReceipt", txHash)
+	if err == nil {
+		if r == nil {
+			return nil, coreth.NotFound
+		}
+	}
+	return r, err
+}
+
+func toBlockNumArg(number *big.Int) string {
+	// The Ethereum implementation uses a different mapping from
+	// negative numbers to special strings (latest, pending) then is
+	// used on its server side. See rpc/types.go for the comparison.
+	// if number == nil {
+	// 	return "latest"
+	// }
+	// pending := big.NewInt(-1)
+	// if number.Cmp(pending) == 0 {
+	// 	return "pending"
+	// }
+
+	// In Coreth, latest, pending, and accepted are all treated the same
+	// therefore, if [number] is nil or a negative number in [-3, -1]
+	// we want the latest accepted block
+	if number == nil {
+		return "latest"
+	}
+	low := big.NewInt(-3)
+	high := big.NewInt(-1)
+	if number.Cmp(low) >= 0 && number.Cmp(high) <= 0 {
+		return "latest"
+	}
+	return hexutil.EncodeBig(number)
+}
+
+type rpcProgress struct {
+	StartingBlock hexutil.Uint64
+	CurrentBlock  hexutil.Uint64
+	HighestBlock  hexutil.Uint64
+	PulledStates  hexutil.Uint64
+	KnownStates   hexutil.Uint64
+}
+
+// SyncProgress retrieves the current progress of the sync algorithm. If there's
+// no sync currently running, it returns nil.
+// eth_syncing is not implemented in Coreth
+// func (ec *Client) SyncProgress(ctx context.Context) (*coreth.SyncProgress, error) {
+// 	var raw json.RawMessage
+// 	if err := ec.c.CallContext(ctx, &raw, "eth_syncing"); err != nil {
+// 		return nil, err
+// 	}
+// 	// Handle the possible response types
+// 	var syncing bool
+// 	if err := json.Unmarshal(raw, &syncing); err == nil {
+// 		return nil, nil // Not syncing (always false)
+// 	}
+// 	var progress *rpcProgress
+// 	if err := json.Unmarshal(raw, &progress); err != nil {
+// 		return nil, err
+// 	}
+// 	return &coreth.SyncProgress{
+// 		StartingBlock: uint64(progress.StartingBlock),
+// 		CurrentBlock:  uint64(progress.CurrentBlock),
+// 		HighestBlock:  uint64(progress.HighestBlock),
+// 		PulledStates:  uint64(progress.PulledStates),
+// 		KnownStates:   uint64(progress.KnownStates),
+// 	}, nil
+// }
+
+// SubscribeNewHead subscribes to notifications about the current blockchain head
+// on the given channel.
+func (ec *Client) SubscribeNewHead(ctx context.Context, ch chan<- *types.Header) (coreth.Subscription, error) {
+	return ec.c.EthSubscribe(ctx, ch, "newHeads")
+}
+
+// State Access
+
+// NetworkID returns the network ID (also known as the chain ID) for this chain.
+func (ec *Client) NetworkID(ctx context.Context) (*big.Int, error) {
+	version := new(big.Int)
+	var ver string
+	if err := ec.c.CallContext(ctx, &ver, "net_version"); err != nil {
+		return nil, err
+	}
+	if _, ok := version.SetString(ver, 10); !ok {
+		return nil, fmt.Errorf("invalid net_version result %q", ver)
+	}
+	return version, nil
+}
+
+// BalanceAt returns the wei balance of the given account.
+// The block number can be nil, in which case the balance is taken from the latest known block.
+func (ec *Client) BalanceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (*big.Int, error) {
+	var result hexutil.Big
+	err := ec.c.CallContext(ctx, &result, "eth_getBalance", account, toBlockNumArg(blockNumber))
+	return (*big.Int)(&result), err
+}
+
+// AssetBalanceAt returns the [assetID] balance of the given account
+// The block number can be nil, in which case the balance is taken from the latest known block.
+func (ec *Client) AssetBalanceAt(ctx context.Context, account common.Address, assetID ids.ID, blockNumber *big.Int) (*big.Int, error) {
+	var result hexutil.Big
+	err := ec.c.CallContext(ctx, &result, "eth_getBalance", account, toBlockNumArg(blockNumber), assetID)
+	return (*big.Int)(&result), err
+}
+
+// StorageAt returns the value of key in the contract storage of the given account.
+// The block number can be nil, in which case the value is taken from the latest known block.
+func (ec *Client) StorageAt(ctx context.Context, account common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error) {
+	var result hexutil.Bytes
+	err := ec.c.CallContext(ctx, &result, "eth_getStorageAt", account, key, toBlockNumArg(blockNumber))
+	return result, err
+}
+
+// CodeAt returns the contract code of the given account.
+// The block number can be nil, in which case the code is taken from the latest known block.
+func (ec *Client) CodeAt(ctx context.Context, account common.Address, blockNumber *big.Int) ([]byte, error) {
+	var result hexutil.Bytes
+	err := ec.c.CallContext(ctx, &result, "eth_getCode", account, toBlockNumArg(blockNumber))
+	return result, err
+}
+
+// NonceAt returns the account nonce of the given account.
+// The block number can be nil, in which case the nonce is taken from the latest known block.
+func (ec *Client) NonceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (uint64, error) {
+	var result hexutil.Uint64
+	err := ec.c.CallContext(ctx, &result, "eth_getTransactionCount", account, toBlockNumArg(blockNumber))
+	return uint64(result), err
+}
+
+// Filters
+
+// FilterLogs executes a filter query.
+func (ec *Client) FilterLogs(ctx context.Context, q coreth.FilterQuery) ([]types.Log, error) {
+	var result []types.Log
+	arg, err := toFilterArg(q)
+	if err != nil {
+		return nil, err
+	}
+	err = ec.c.CallContext(ctx, &result, "eth_getLogs", arg)
+	return result, err
+}
+
+// SubscribeFilterLogs subscribes to the results of a streaming filter query.
+func (ec *Client) SubscribeFilterLogs(ctx context.Context, q coreth.FilterQuery, ch chan<- types.Log) (coreth.Subscription, error) {
+	arg, err := toFilterArg(q)
+	if err != nil {
+		return nil, err
+	}
+	return ec.c.EthSubscribe(ctx, ch, "logs", arg)
+}
+
+func toFilterArg(q coreth.FilterQuery) (interface{}, error) {
+	arg := map[string]interface{}{
+		"address": q.Addresses,
+		"topics":  q.Topics,
+	}
+	if q.BlockHash != nil {
+		arg["blockHash"] = *q.BlockHash
+		if q.FromBlock != nil || q.ToBlock != nil {
+			return nil, fmt.Errorf("cannot specify both BlockHash and FromBlock/ToBlock")
+		}
+	} else {
+		if q.FromBlock == nil {
+			arg["fromBlock"] = "0x0"
+		} else {
+			arg["fromBlock"] = toBlockNumArg(q.FromBlock)
+		}
+		arg["toBlock"] = toBlockNumArg(q.ToBlock)
+	}
+	return arg, nil
+}
+
+// Pending State is irrelevant in Coreth
+
+// // PendingBalanceAt returns the wei balance of the given account in the pending state.
+// func (ec *Client) PendingBalanceAt(ctx context.Context, account common.Address) (*big.Int, error) {
+// 	var result hexutil.Big
+// 	err := ec.c.CallContext(ctx, &result, "eth_getBalance", account, "pending")
+// 	return (*big.Int)(&result), err
+// }
+
+// // PendingStorageAt returns the value of key in the contract storage of the given account in the pending state.
+// func (ec *Client) PendingStorageAt(ctx context.Context, account common.Address, key common.Hash) ([]byte, error) {
+// 	var result hexutil.Bytes
+// 	err := ec.c.CallContext(ctx, &result, "eth_getStorageAt", account, key, "pending")
+// 	return result, err
+// }
+
+// // PendingCodeAt returns the contract code of the given account in the pending state.
+// func (ec *Client) PendingCodeAt(ctx context.Context, account common.Address) ([]byte, error) {
+// 	var result hexutil.Bytes
+// 	err := ec.c.CallContext(ctx, &result, "eth_getCode", account, "pending")
+// 	return result, err
+// }
+
+// // PendingNonceAt returns the account nonce of the given account in the pending state.
+// // This is the nonce that should be used for the next transaction.
+// func (ec *Client) PendingNonceAt(ctx context.Context, account common.Address) (uint64, error) {
+// 	var result hexutil.Uint64
+// 	err := ec.c.CallContext(ctx, &result, "eth_getTransactionCount", account, "pending")
+// 	return uint64(result), err
+// }
+
+// // PendingTransactionCount returns the total number of transactions in the pending state.
+// func (ec *Client) PendingTransactionCount(ctx context.Context) (uint, error) {
+// 	var num hexutil.Uint
+// 	err := ec.c.CallContext(ctx, &num, "eth_getBlockTransactionCountByNumber", "pending")
+// 	return uint(num), err
+// }
+
+// TODO: SubscribePendingTransactions (needs server side)
+
+// Contract Calling
+
+// CallContract executes a message call transaction, which is directly executed in the VM
+// of the node, but never mined into the blockchain.
+//
+// blockNumber selects the block height at which the call runs. It can be nil, in which
+// case the code is taken from the latest known block. Note that state from very old
+// blocks might not be available.
+func (ec *Client) CallContract(ctx context.Context, msg coreth.CallMsg, blockNumber *big.Int) ([]byte, error) {
+	var hex hexutil.Bytes
+	err := ec.c.CallContext(ctx, &hex, "eth_call", toCallArg(msg), toBlockNumArg(blockNumber))
+	if err != nil {
+		return nil, err
+	}
+	return hex, nil
+}
+
+// // PendingCallContract executes a message call transaction using the EVM.
+// // The state seen by the contract call is the pending state.
+// func (ec *Client) PendingCallContract(ctx context.Context, msg coreth.CallMsg) ([]byte, error) {
+// 	var hex hexutil.Bytes
+// 	err := ec.c.CallContext(ctx, &hex, "eth_call", toCallArg(msg), "pending")
+// 	if err != nil {
+// 		return nil, err
+// 	}
+// 	return hex, nil
+// }
+
+// SuggestGasPrice retrieves the currently suggested gas price to allow a timely
+// execution of a transaction.
+func (ec *Client) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
+	var hex hexutil.Big
+	if err := ec.c.CallContext(ctx, &hex, "eth_gasPrice"); err != nil {
+		return nil, err
+	}
+	return (*big.Int)(&hex), nil
+}
+
+// EstimateGas tries to estimate the gas needed to execute a specific transaction based on
+// the current pending state of the backend blockchain. There is no guarantee that this is
+// the true gas limit requirement as other transactions may be added or removed by miners,
+// but it should provide a basis for setting a reasonable default.
+func (ec *Client) EstimateGas(ctx context.Context, msg coreth.CallMsg) (uint64, error) {
+	var hex hexutil.Uint64
+	err := ec.c.CallContext(ctx, &hex, "eth_estimateGas", toCallArg(msg))
+	if err != nil {
+		return 0, err
+	}
+	return uint64(hex), nil
+}
+
+// SendTransaction injects a signed transaction into the pending pool for execution.
+//
+// If the transaction was a contract creation use the TransactionReceipt method to get the
+// contract address after the transaction has been mined.
+func (ec *Client) SendTransaction(ctx context.Context, tx *types.Transaction) error {
+	data, err := rlp.EncodeToBytes(tx)
+	if err != nil {
+		return err
+	}
+	return ec.c.CallContext(ctx, nil, "eth_sendRawTransaction", hexutil.Encode(data))
+}
+
+func toCallArg(msg coreth.CallMsg) interface{} {
+	arg := map[string]interface{}{
+		"from": msg.From,
+		"to":   msg.To,
+	}
+	if len(msg.Data) > 0 {
+		arg["data"] = hexutil.Bytes(msg.Data)
+	}
+	if msg.Value != nil {
+		arg["value"] = (*hexutil.Big)(msg.Value)
+	}
+	if msg.Gas != 0 {
+		arg["gas"] = hexutil.Uint64(msg.Gas)
+	}
+	if msg.GasPrice != nil {
+		arg["gasPrice"] = (*hexutil.Big)(msg.GasPrice)
+	}
+	return arg
+}
diff --git a/ethclient/signer.go b/ethclient/signer.go
new file mode 100644
index 0000000..4a9f645
--- /dev/null
+++ b/ethclient/signer.go
@@ -0,0 +1,59 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package ethclient
+
+import (
+	"errors"
+	"math/big"
+
+	"github.com/ava-labs/coreth/core/types"
+	"github.com/ethereum/go-ethereum/common"
+)
+
+// senderFromServer is a types.Signer that remembers the sender address returned by the RPC
+// server. It is stored in the transaction's sender address cache to avoid an additional
+// request in TransactionSender.
+type senderFromServer struct {
+	addr      common.Address
+	blockhash common.Hash
+}
+
+var errNotCached = errors.New("sender not cached")
+
+func setSenderFromServer(tx *types.Transaction, addr common.Address, block common.Hash) {
+	// Use types.Sender for side-effect to store our signer into the cache.
+	types.Sender(&senderFromServer{addr, block}, tx)
+}
+
+func (s *senderFromServer) Equal(other types.Signer) bool {
+	os, ok := other.(*senderFromServer)
+	return ok && os.blockhash == s.blockhash
+}
+
+func (s *senderFromServer) Sender(tx *types.Transaction) (common.Address, error) {
+	if s.blockhash == (common.Hash{}) {
+		return common.Address{}, errNotCached
+	}
+	return s.addr, nil
+}
+
+func (s *senderFromServer) Hash(tx *types.Transaction) common.Hash {
+	panic("can't sign with senderFromServer")
+}
+func (s *senderFromServer) SignatureValues(tx *types.Transaction, sig []byte) (R, S, V *big.Int, err error) {
+	panic("can't sign with senderFromServer")
+}