1 files changed, 231 insertions, 0 deletions
diff --git a/accounts/external/backend.go b/accounts/external/backend.go
new file mode 100644
index 0000000..16e201d
--- /dev/null
+++ b/accounts/external/backend.go
@@ -0,0 +1,231 @@
+// Copyright 2019 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 external
+
+import (
+	"fmt"
+	"math/big"
+	"sync"
+
+	"github.com/ava-labs/coreth/accounts"
+	"github.com/ava-labs/coreth/core/types"
+	"github.com/ava-labs/coreth/internal/ethapi"
+	"github.com/ava-labs/coreth/rpc"
+	"github.com/ava-labs/go-ethereum"
+	"github.com/ava-labs/go-ethereum/common"
+	"github.com/ava-labs/go-ethereum/common/hexutil"
+	"github.com/ava-labs/go-ethereum/event"
+	"github.com/ava-labs/go-ethereum/log"
+	"github.com/ava-labs/go-ethereum/signer/core"
+)
+
+type ExternalBackend struct {
+	signers []accounts.Wallet
+}
+
+func (eb *ExternalBackend) Wallets() []accounts.Wallet {
+	return eb.signers
+}
+
+func NewExternalBackend(endpoint string) (*ExternalBackend, error) {
+	signer, err := NewExternalSigner(endpoint)
+	if err != nil {
+		return nil, err
+	}
+	return &ExternalBackend{
+		signers: []accounts.Wallet{signer},
+	}, nil
+}
+
+func (eb *ExternalBackend) Subscribe(sink chan<- accounts.WalletEvent) event.Subscription {
+	return event.NewSubscription(func(quit <-chan struct{}) error {
+		<-quit
+		return nil
+	})
+}
+
+// ExternalSigner provides an API to interact with an external signer (clef)
+// It proxies request to the external signer while forwarding relevant
+// request headers
+type ExternalSigner struct {
+	client   *rpc.Client
+	endpoint string
+	status   string
+	cacheMu  sync.RWMutex
+	cache    []accounts.Account
+}
+
+func NewExternalSigner(endpoint string) (*ExternalSigner, error) {
+	client, err := rpc.Dial(endpoint)
+	if err != nil {
+		return nil, err
+	}
+	extsigner := &ExternalSigner{
+		client:   client,
+		endpoint: endpoint,
+	}
+	// Check if reachable
+	version, err := extsigner.pingVersion()
+	if err != nil {
+		return nil, err
+	}
+	extsigner.status = fmt.Sprintf("ok [version=%v]", version)
+	return extsigner, nil
+}
+
+func (api *ExternalSigner) URL() accounts.URL {
+	return accounts.URL{
+		Scheme: "extapi",
+		Path:   api.endpoint,
+	}
+}
+
+func (api *ExternalSigner) Status() (string, error) {
+	return api.status, nil
+}
+
+func (api *ExternalSigner) Open(passphrase string) error {
+	return fmt.Errorf("operation not supported on external signers")
+}
+
+func (api *ExternalSigner) Close() error {
+	return fmt.Errorf("operation not supported on external signers")
+}
+
+func (api *ExternalSigner) Accounts() []accounts.Account {
+	var accnts []accounts.Account
+	res, err := api.listAccounts()
+	if err != nil {
+		log.Error("account listing failed", "error", err)
+		return accnts
+	}
+	for _, addr := range res {
+		accnts = append(accnts, accounts.Account{
+			URL: accounts.URL{
+				Scheme: "extapi",
+				Path:   api.endpoint,
+			},
+			Address: addr,
+		})
+	}
+	api.cacheMu.Lock()
+	api.cache = accnts
+	api.cacheMu.Unlock()
+	return accnts
+}
+
+func (api *ExternalSigner) Contains(account accounts.Account) bool {
+	api.cacheMu.RLock()
+	defer api.cacheMu.RUnlock()
+	for _, a := range api.cache {
+		if a.Address == account.Address && (account.URL == (accounts.URL{}) || account.URL == api.URL()) {
+			return true
+		}
+	}
+	return false
+}
+
+func (api *ExternalSigner) Derive(path accounts.DerivationPath, pin bool) (accounts.Account, error) {
+	return accounts.Account{}, fmt.Errorf("operation not supported on external signers")
+}
+
+func (api *ExternalSigner) SelfDerive(bases []accounts.DerivationPath, chain ethereum.ChainStateReader) {
+	log.Error("operation SelfDerive not supported on external signers")
+}
+
+func (api *ExternalSigner) signHash(account accounts.Account, hash []byte) ([]byte, error) {
+	return []byte{}, fmt.Errorf("operation not supported on external signers")
+}
+
+// SignData signs keccak256(data). The mimetype parameter describes the type of data being signed
+func (api *ExternalSigner) SignData(account accounts.Account, mimeType string, data []byte) ([]byte, error) {
+	var res hexutil.Bytes
+	var signAddress = common.NewMixedcaseAddress(account.Address)
+	if err := api.client.Call(&res, "account_signData",
+		mimeType,
+		&signAddress, // Need to use the pointer here, because of how MarshalJSON is defined
+		hexutil.Encode(data)); err != nil {
+		return nil, err
+	}
+	// If V is on 27/28-form, convert to to 0/1 for Clique
+	if mimeType == accounts.MimetypeClique && (res[64] == 27 || res[64] == 28) {
+		res[64] -= 27 // Transform V from 27/28 to 0/1 for Clique use
+	}
+	return res, nil
+}
+
+func (api *ExternalSigner) SignText(account accounts.Account, text []byte) ([]byte, error) {
+	var res hexutil.Bytes
+	var signAddress = common.NewMixedcaseAddress(account.Address)
+	if err := api.client.Call(&res, "account_signData",
+		accounts.MimetypeTextPlain,
+		&signAddress, // Need to use the pointer here, because of how MarshalJSON is defined
+		hexutil.Encode(text)); err != nil {
+		return nil, err
+	}
+	return res, nil
+}
+
+func (api *ExternalSigner) SignTx(account accounts.Account, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
+	res := ethapi.SignTransactionResult{}
+	data := hexutil.Bytes(tx.Data())
+	var to *common.MixedcaseAddress
+	if tx.To() != nil {
+		t := common.NewMixedcaseAddress(*tx.To())
+		to = &t
+	}
+	args := &core.SendTxArgs{
+		Data:     &data,
+		Nonce:    hexutil.Uint64(tx.Nonce()),
+		Value:    hexutil.Big(*tx.Value()),
+		Gas:      hexutil.Uint64(tx.Gas()),
+		GasPrice: hexutil.Big(*tx.GasPrice()),
+		To:       to,
+		From:     common.NewMixedcaseAddress(account.Address),
+	}
+	if err := api.client.Call(&res, "account_signTransaction", args); err != nil {
+		return nil, err
+	}
+	return res.Tx, nil
+}
+
+func (api *ExternalSigner) SignTextWithPassphrase(account accounts.Account, passphrase string, text []byte) ([]byte, error) {
+	return []byte{}, fmt.Errorf("password-operations not supported on external signers")
+}
+
+func (api *ExternalSigner) SignTxWithPassphrase(account accounts.Account, passphrase string, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
+	return nil, fmt.Errorf("password-operations not supported on external signers")
+}
+func (api *ExternalSigner) SignDataWithPassphrase(account accounts.Account, passphrase, mimeType string, data []byte) ([]byte, error) {
+	return nil, fmt.Errorf("password-operations not supported on external signers")
+}
+
+func (api *ExternalSigner) listAccounts() ([]common.Address, error) {
+	var res []common.Address
+	if err := api.client.Call(&res, "account_list"); err != nil {
+		return nil, err
+	}
+	return res, nil
+}
+
+func (api *ExternalSigner) pingVersion() (string, error) {
+	var v string
+	if err := api.client.Call(&v, "account_version"); err != nil {
+		return "", err
+	}
+	return v, nil
+}