68 lines
1.8 KiB
Go
68 lines
1.8 KiB
Go
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package contracts
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import (
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"context"
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"math/big"
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ethereum "github.com/ethereum/go-ethereum"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/common/hexutil"
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)
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type RPCClient interface {
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CallContext(ctx context.Context, result interface{}, method string, args ...interface{}) error
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}
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type ContractCaller struct {
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c RPCClient
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}
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func NewContractCaller(c RPCClient) *ContractCaller {
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return &ContractCaller{
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c: c,
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}
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}
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// CodeAt returns the contract code of the given account.
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// The block number can be nil, in which case the code is taken from the latest known block.
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func (cc *ContractCaller) CodeAt(ctx context.Context, account common.Address, blockNumber *big.Int) ([]byte, error) {
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var result hexutil.Bytes
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err := cc.c.CallContext(ctx, &result, "eth_getCode", account, "latest")
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return result, err
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}
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// CallContract executes a message call transaction, which is directly executed in the VM
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// of the node, but never mined into the blockchain.
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//
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// blockNumber selects the block height at which the call runs. It can be nil, in which
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// case the code is taken from the latest known block. Note that state from very old
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// blocks might not be available.
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func (cc *ContractCaller) CallContract(ctx context.Context, msg ethereum.CallMsg, blockNumber *big.Int) ([]byte, error) {
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var hex hexutil.Bytes
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err := cc.c.CallContext(ctx, &hex, "eth_call", toCallArg(msg), "latest")
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if err != nil {
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return nil, err
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}
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return hex, nil
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}
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func toCallArg(msg ethereum.CallMsg) interface{} {
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arg := map[string]interface{}{
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"from": msg.From,
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"to": msg.To,
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}
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if len(msg.Data) > 0 {
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arg["data"] = hexutil.Bytes(msg.Data)
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}
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if msg.Value != nil {
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arg["value"] = (*hexutil.Big)(msg.Value)
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}
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if msg.Gas != 0 {
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arg["gas"] = hexutil.Uint64(msg.Gas)
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}
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if msg.GasPrice != nil {
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arg["gasPrice"] = (*hexutil.Big)(msg.GasPrice)
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}
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return arg
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}
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