1 files changed, 202 insertions, 0 deletions
diff --git a/accounts/abi/bind/backends/remote.go b/accounts/abi/bind/backends/remote.go
new file mode 100644
index 000000000..7177809bb
--- /dev/null
+++ b/accounts/abi/bind/backends/remote.go
@@ -0,0 +1,202 @@
+// 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 backends
+
+import (
+	"encoding/json"
+	"fmt"
+	"math/big"
+	"sync"
+	"sync/atomic"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+// rpcBackend implements bind.ContractBackend, and acts as the data provider to
+// Ethereum contracts bound to Go structs. It uses an RPC connection to delegate
+// all its functionality.
+//
+// Note: The current implementation is a blocking one. This should be replaced
+// by a proper async version when a real RPC client is created.
+type rpcBackend struct {
+	client rpc.Client // RPC client connection to interact with an API server
+	autoid uint32     // ID number to use for the next API request
+	lock   sync.Mutex // Singleton access until we get to request multiplexing
+}
+
+// NewRPCBackend creates a new binding backend to an RPC provider that can be
+// used to interact with remote contracts.
+func NewRPCBackend(client rpc.Client) bind.ContractBackend {
+	return &rpcBackend{
+		client: client,
+	}
+}
+
+// request is a JSON RPC request package assembled internally from the client
+// method calls.
+type request struct {
+	JsonRpc string        `json:"jsonrpc"` // Version of the JSON RPC protocol, always set to 2.0
+	Id      int           `json:"id"`      // Auto incrementing ID number for this request
+	Method  string        `json:"method"`  // Remote procedure name to invoke on the server
+	Params  []interface{} `json:"params"`  // List of parameters to pass through (keep types simple)
+}
+
+// response is a JSON RPC response package sent back from the API server.
+type response struct {
+	JsonRpc string          `json:"jsonrpc"` // Version of the JSON RPC protocol, always set to 2.0
+	Id      int             `json:"id"`      // Auto incrementing ID number for this request
+	Error   json.RawMessage `json:"error"`   // Any error returned by the remote side
+	Result  json.RawMessage `json:"result"`  // Whatever the remote side sends us in reply
+}
+
+// request forwards an API request to the RPC server, and parses the response.
+//
+// This is currently painfully non-concurrent, but it will have to do until we
+// find the time for niceties like this :P
+func (backend *rpcBackend) request(method string, params []interface{}) (json.RawMessage, error) {
+	backend.lock.Lock()
+	defer backend.lock.Unlock()
+
+	// Ugly hack to serialize an empty list properly
+	if params == nil {
+		params = []interface{}{}
+	}
+	// Assemble the request object
+	req := &request{
+		JsonRpc: "2.0",
+		Id:      int(atomic.AddUint32(&backend.autoid, 1)),
+		Method:  method,
+		Params:  params,
+	}
+	if err := backend.client.Send(req); err != nil {
+		return nil, err
+	}
+	res := new(response)
+	if err := backend.client.Recv(res); err != nil {
+		return nil, err
+	}
+	if len(res.Error) > 0 {
+		return nil, fmt.Errorf("remote error: %s", string(res.Error))
+	}
+	return res.Result, nil
+}
+
+// ContractCall implements ContractCaller.ContractCall, delegating the execution of
+// a contract call to the remote node, returning the reply to for local processing.
+func (b *rpcBackend) ContractCall(contract common.Address, data []byte, pending bool) ([]byte, error) {
+	// Pack up the request into an RPC argument
+	args := struct {
+		To   common.Address `json:"to"`
+		Data string         `json:"data"`
+	}{
+		To:   contract,
+		Data: common.ToHex(data),
+	}
+	// Execute the RPC call and retrieve the response
+	block := "latest"
+	if pending {
+		block = "pending"
+	}
+	res, err := b.request("eth_call", []interface{}{args, block})
+	if err != nil {
+		return nil, err
+	}
+	var hex string
+	if err := json.Unmarshal(res, &hex); err != nil {
+		return nil, err
+	}
+	// Convert the response back to a Go byte slice and return
+	return common.FromHex(hex), nil
+}
+
+// AccountNonce implements ContractTransactor.AccountNonce, delegating the
+// current account nonce retrieval to the remote node.
+func (b *rpcBackend) AccountNonce(account common.Address) (uint64, error) {
+	res, err := b.request("eth_getTransactionCount", []interface{}{account.Hex(), "pending"})
+	if err != nil {
+		return 0, err
+	}
+	var hex string
+	if err := json.Unmarshal(res, &hex); err != nil {
+		return 0, err
+	}
+	return new(big.Int).SetBytes(common.FromHex(hex)).Uint64(), nil
+}
+
+// GasPrice implements ContractTransactor.GasPrice, delegating the gas price
+// oracle request to the remote node.
+func (b *rpcBackend) GasPrice() (*big.Int, error) {
+	res, err := b.request("eth_gasPrice", nil)
+	if err != nil {
+		return nil, err
+	}
+	var hex string
+	if err := json.Unmarshal(res, &hex); err != nil {
+		return nil, err
+	}
+	return new(big.Int).SetBytes(common.FromHex(hex)), nil
+}
+
+// GasLimit implements ContractTransactor.GasLimit, delegating the gas estimation
+// to the remote node.
+func (b *rpcBackend) GasLimit(sender common.Address, contract *common.Address, value *big.Int, data []byte) (*big.Int, error) {
+	// Pack up the request into an RPC argument
+	args := struct {
+		From  common.Address  `json:"from"`
+		To    *common.Address `json:"to"`
+		Value *rpc.HexNumber  `json:"value"`
+		Data  string          `json:"data"`
+	}{
+		From:  sender,
+		To:    contract,
+		Data:  common.ToHex(data),
+		Value: rpc.NewHexNumber(value),
+	}
+	// Execute the RPC call and retrieve the response
+	res, err := b.request("eth_estimateGas", []interface{}{args})
+	if err != nil {
+		return nil, err
+	}
+	var hex string
+	if err := json.Unmarshal(res, &hex); err != nil {
+		return nil, err
+	}
+	// Convert the response back to a Go byte slice and return
+	return new(big.Int).SetBytes(common.FromHex(hex)), nil
+}
+
+// Transact implements ContractTransactor.SendTransaction, delegating the raw
+// transaction injection to the remote node.
+func (b *rpcBackend) SendTransaction(tx *types.Transaction) error {
+	data, err := rlp.EncodeToBytes(tx)
+	if err != nil {
+		return err
+	}
+	res, err := b.request("eth_sendRawTransaction", []interface{}{common.ToHex(data)})
+	if err != nil {
+		return err
+	}
+	var hex string
+	if err := json.Unmarshal(res, &hex); err != nil {
+		return err
+	}
+	return nil
+}