// Copyright (c) 2019-2020 The Zcash developers // Distributed under the MIT software license, see the accompanying // file COPYING or https://www.opensource.org/licenses/mit-license.php . // // This tool reads a set of files, each containing a list of transactions // (one per line, can be empty), and writes to stdout a list of blocks, // one per input file, in hex format (same as zcash-cli getblock 12345 0), // each on a separate line. Each fake block contains a fake coinbase // transaction and all of the transactions in the corresponding file. // The default start height is 1000, so the program expects to find // files blocks/1000.txt, blocks/1001.txt, ... // // Typical way to run this program to create 6 blocks, all empty except // for the fifth, which contains one transaction: // $ mkdir blocks // $ touch blocks/{1000,1001,1002,1003,1004,1005}.txt // $ echo "0400008085202f8901950521a79e89ed418a4b506f42e9829739b1ca516d4c590bddb4465b4b347bb2000000006a4730440220142920f2a9240c5c64406668c9a16d223bd01db33a773beada7f9c9b930cf02b0220171cbee9232f9c5684eb918db70918e701b86813732871e1bec6fbfb38194f53012102975c020dd223263d2a9bfff2fa6004df4c07db9f01c531967546ef941e2fcfbffeffffff026daf9b00000000001976a91461af073e7679f06677c83aa48f205e4b98feb8d188ac61760356100000001976a91406f6b9a7e1525ee12fd77af9b94a54179785011b88ac4c880b007f880b000000000000000000000000" > blocks/1004.txt // $ go run testtools/genblocks/main.go >testdata/default-darkside-blocks // // Alternative way to create the empty files: // $ seq 1000 1005 | while read i; do touch blocks/$i.txt; done package main import ( "bufio" "crypto/sha256" "encoding/hex" "flag" "fmt" "os" "path" "strconv" "strings" "github.com/zcash/lightwalletd/parser" ) type options struct { startHeight int blocksDir string } func main() { opts := &options{} flag.IntVar(&opts.startHeight, "start-height", 1000, "generated blocks start at this height") flag.StringVar(&opts.blocksDir, "blocks-dir", "./blocks", "directory containing .txt for each block height , with one hex-encoded transaction per line") flag.Parse() prevhash := make([]byte, 32) curHeight := opts.startHeight // Keep opening .txt and incrementing until the file doesn't exist. for { testBlocks, err := os.Open(path.Join(opts.blocksDir, strconv.Itoa(curHeight)+".txt")) if err != nil { break } scan := bufio.NewScanner(testBlocks) fakeCoinbase := "0400008085202f890100000000000000000000000000000000000000000000000000" + "00000000000000ffffffff2a03d12c0c00043855975e464b8896790758f824ceac97836" + "22c17ed38f1669b8a45ce1da857dbbe7950e2ffffffff02a0ebce1d000000001976a914" + "7ed15946ec14ae0cd8fa8991eb6084452eb3f77c88ac405973070000000017a914e445cf" + "a944b6f2bdacefbda904a81d5fdd26d77f8700000000000000000000000000000000000000" // This coinbase transaction was pulled from block 797905, whose // little-endian encoding is 0xD12C0C00. Replace it with the block // number we want. fakeCoinbase = strings.Replace(fakeCoinbase, "d12c0c00", fmt.Sprintf("%02x", curHeight&0xFF)+ fmt.Sprintf("%02x", (curHeight>>8)&0xFF)+ fmt.Sprintf("%02x", (curHeight>>16)&0xFF)+ fmt.Sprintf("%02x", (curHeight>>24)&0xFF), 1) var numTransactions uint = 1 // coinbase allTransactionsHex := "" for scan.Scan() { // each line (hex-encoded transaction) allTransactionsHex += scan.Text() numTransactions++ } if err = scan.Err(); err != nil { panic("line too long!") } if numTransactions > 65535 { panic(fmt.Sprint("too many transactions ", numTransactions, " maximum 65535")) } hashOfTxnsAndHeight := sha256.Sum256([]byte(allTransactionsHex + "#" + string(rune(curHeight)))) // These fields do not need to be valid for the lightwalletd/wallet stack to work. // The lightwalletd/wallet stack rely on the miners to validate these. // Make the block header depend on height + all transactions (in an incorrect way) blockHeader := &parser.BlockHeader{ RawBlockHeader: &parser.RawBlockHeader{ Version: 4, HashPrevBlock: prevhash, HashMerkleRoot: hashOfTxnsAndHeight[:], HashFinalSaplingRoot: make([]byte, 32), Time: 1, NBitsBytes: make([]byte, 4), Nonce: make([]byte, 32), Solution: make([]byte, 1344), }, } headerBytes, err := blockHeader.MarshalBinary() if err != nil { panic(fmt.Sprint("Cannot marshal block header: ", err)) } fmt.Print(hex.EncodeToString(headerBytes)) // After the header, there's a compactsize representation of the number of transactions. if numTransactions < 253 { fmt.Printf("%02x", numTransactions) } else { fmt.Printf("%02x%02x%02x", 253, numTransactions%256, numTransactions/256) } fmt.Printf("%s%s\n", fakeCoinbase, allTransactionsHex) curHeight++ prevhash = blockHeader.GetEncodableHash() } }