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etherscan.go
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etherscan.go
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package etherscan
import (
"encoding/json"
"fmt"
"strconv"
"strings"
"github.com/laizy/web3"
"github.com/laizy/web3/jsonrpc/codec"
"github.com/valyala/fasthttp"
)
// Etherscan is a provider using the Etherscan api
type Etherscan struct {
client fasthttp.Client
url string
apiKey string
}
// NewEtherscanFromNetwork creates a new client from the network id
func NewEtherscanFromNetwork(n web3.Network, apiKey string) (*Etherscan, error) {
var url string
switch n {
case web3.Mainnet:
url = "https://api.etherscan.io"
case web3.Ropsten:
url = "https://ropsten.etherscan.io"
case web3.Rinkeby:
url = "https://rinkeby.etherscan.io"
case web3.Goerli:
url = "https://goerli.etherscan.io"
default:
return nil, fmt.Errorf("unknwon network id %d", n)
}
return NewEtherscan(url, apiKey), nil
}
// NewEtherscan creates a new Etherscan service from a url
func NewEtherscan(url, apiKey string) *Etherscan {
return &Etherscan{url: url}
}
type proxyResponse struct {
Status string
Message string
Result json.RawMessage
}
// Query sends a query to Etherscan
func (e *Etherscan) Query(module, action string, out interface{}, params map[string]string) error {
url := fmt.Sprintf("%s/api?module=%s&action=%s", e.url, module, action)
if len(params) != 0 {
res := []string{}
for k, v := range params {
res = append(res, k+"="+v)
}
url += "&" + strings.Join(res, "&")
}
if e.apiKey != "" {
url = url + "&apikey=" + e.apiKey
}
req := fasthttp.AcquireRequest()
res := fasthttp.AcquireResponse()
defer fasthttp.ReleaseRequest(req)
defer fasthttp.ReleaseResponse(res)
req.SetRequestURI(url)
req.Header.SetMethod("GET")
if err := e.client.Do(req, res); err != nil {
return err
}
// Decode json-rpc response
var result json.RawMessage
if module == "proxy" {
var response codec.Response
if err := json.Unmarshal(res.Body(), &response); err != nil {
return err
}
if response.Error != nil {
return response.Error
}
result = response.Result
} else {
var response proxyResponse
if err := json.Unmarshal(res.Body(), &response); err != nil {
return err
}
result = response.Result
}
if err := json.Unmarshal(result, out); err != nil {
return err
}
return nil
}
// BlockNumber returns the number of most recent block.
func (e *Etherscan) BlockNumber() (uint64, error) {
var out string
if err := e.Query("proxy", "eth_blockNumber", &out, nil); err != nil {
return 0, err
}
return parseUint64orHex(out)
}
// GetBlockByNumber returns information about a block by block number.
func (e *Etherscan) GetBlockByNumber(i web3.BlockNumber, full bool) (*web3.Block, error) {
var b *web3.Block
params := map[string]string{
"tag": i.String(),
"boolean": strconv.FormatBool(full),
}
if err := e.Query("proxy", "eth_getBlockByNumber", &b, params); err != nil {
return nil, err
}
return b, nil
}
func parseUint64orHex(str string) (uint64, error) {
base := 10
if strings.HasPrefix(str, "0x") {
str = str[2:]
base = 16
}
return strconv.ParseUint(str, base, 64)
}