Steven Polley
e9466bebc5
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82 lines
2.4 KiB
Go
82 lines
2.4 KiB
Go
package bitcoinElectrum
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import (
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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"sync/atomic"
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"github.com/btcsuite/btcd/btcutil"
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"github.com/btcsuite/btcd/btcutil/hdkeychain"
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"github.com/btcsuite/btcd/chaincfg"
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"github.com/btcsuite/btcd/txscript"
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)
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// Derives a P2WPKH address at a specific index from a branch key.
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func deriveAddress(branchKey *hdkeychain.ExtendedKey, index uint32) (btcutil.Address, error) {
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childKey, err := branchKey.Derive(index)
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if err != nil {
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return nil, err
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}
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pubKey, err := childKey.ECPubKey()
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if err != nil {
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return nil, err
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}
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// Note: For zpub/vpub, use NewAddressWitnessPubKeyHash.
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// For ypub/upub, use NewAddressScriptHash with a P2WPKH script.
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// For xpub/tpub, use NewAddressPubKeyHash.
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return btcutil.NewAddressWitnessPubKeyHash(btcutil.Hash160(pubKey.SerializeCompressed()), &chaincfg.MainNetParams)
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}
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// Converts a btcutil.Address to an Electrum scripthash.
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func addressToScriptHash(address btcutil.Address) (string, error) {
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script, err := txscript.PayToAddrScript(address)
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if err != nil {
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return "", err
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}
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hash := sha256.Sum256(script)
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// Reverse byte order for Electrum protocol
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for i, j := 0, len(hash)-1; i < j; i, j = i+1, j-1 {
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hash[i], hash[j] = hash[j], hash[i]
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}
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return hex.EncodeToString(hash[:]), nil
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}
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// Scans a derivation branch (m/0 or m/1) for balances until the gap limit is reached.
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func scanBranch(masterKey *hdkeychain.ExtendedKey, branch uint32, gapLimit int, spvServer string) (int64, error) {
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branchKey, err := masterKey.Derive(branch)
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if err != nil {
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return 0, fmt.Errorf("error deriving branch %d: %v", branch, err)
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}
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var branchTotalBalance int64
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unusedAddressCount := 0
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for i := uint32(0); ; i++ {
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if unusedAddressCount >= gapLimit {
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break
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}
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// 3. Derive child address
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address, err := deriveAddress(branchKey, i)
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if err != nil {
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return 0, fmt.Errorf("could not derive address at index %d on branch %d: %v", i, branch, err)
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}
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// 4. Get balance from Electrum server
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balance, err := getAddressBalance(spvServer, address)
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if err != nil {
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return 0, fmt.Errorf("error getting balance for %s: %v", address.EncodeAddress(), err)
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}
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total := balance.Result.Confirmed + balance.Result.Unconfirmed
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if total > 0 {
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atomic.AddInt64(&branchTotalBalance, total)
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unusedAddressCount = 0 // Reset gap counter on finding a used address
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} else {
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unusedAddressCount++
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}
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}
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return branchTotalBalance, nil
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}
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