How to Get Smart Contract Creation Block Time

get-contract-creation-block.go

package main

import (
	"context"
	"fmt"
	"log"
	"math/big"
	"sync"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethclient"
)

type ContractFinder struct {
	client      *ethclient.Client
	latestBlock int64
}

func NewContractFinder(provider string) (*ContractFinder, error) {
	conn, err := ethclient.Dial(provider)
	if err != nil {
		return nil, err
	}
	latestBlock, err := conn.BlockByNumber(context.Background(), nil)
	if err != nil {
		return nil, err
	}

	return &ContractFinder{
		client:      conn,
		latestBlock: latestBlock.Number().Int64(),
	}, nil
}

func (c *ContractFinder) codeLen(contractAddr string, blockNumber int64) int {
	ctx := context.Background()
	data, err := c.client.CodeAt(ctx, common.HexToAddress(contractAddr), big.NewInt(blockNumber))
	if err != nil {
		log.Fatal("Whoops something went wrong!", err)
	}
	return len(data)
}

func (c *ContractFinder) GetContractCreationBlock(contractAddr string) int64 {
	return c.getCreationBlock(contractAddr, 0, c.latestBlock)
}

// use binary search to find the block number where the contract was created
func (c *ContractFinder) getCreationBlock(contractAddr string, startBlock int64, endBlock int64) int64 {
	if startBlock == endBlock {
		return startBlock
	}
	// fmt.Println("contractAddr", contractAddr, "startBlock", startBlock, "endBlock", endBlock)
	midBlock := (startBlock + endBlock) / 2
	codeLen := c.codeLen(contractAddr, midBlock)
	if codeLen > 2 {
		return c.getCreationBlock(contractAddr, startBlock, midBlock)
	} else {
		return c.getCreationBlock(contractAddr, midBlock+1, endBlock)
	}
}

type Data struct {
	address    string
	startBlock int64
}

func worker(cttFinder *ContractFinder, contractChan <-chan Data, resultChan chan<- Data) {
	for data := range contractChan {
		creationBlock := cttFinder.GetContractCreationBlock(data.address)
		resultChan <- Data{data.address, creationBlock}
	}
}

func main() {
	cttFinder, err := NewContractFinder("https://mainnet.infura.io/v3/[YOURKEY]")
	if err != nil {
		log.Fatal("Whoops something went wrong!", err)
	}

	contracts := []string{
		"0x3a4f40631a4f906c2bad353ed06de7a5d3fcb430",
		"0xa4991609c508b6d4fb7156426db0bd49fe298bd8",
	}

	inputChan := make(chan Data)
	resultChan := make(chan Data)

	// write the task into input chan
	go func() {
		defer close(inputChan)
		for _, adr := range contracts {
			inputChan <- Data{adr, 0}
		}
	}()

	// start 4 workers
	var wg sync.WaitGroup
	numberWorkers := 1
	for i := 0; i < numberWorkers; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			worker(cttFinder, inputChan, resultChan)
		}()
	}

	go func() {
		wg.Wait()
		close(resultChan)
	}()

	for r := range resultChan {
		fmt.Println(r)
	}

}