86 lines
2.3 KiB
Go
86 lines
2.3 KiB
Go
// Copyright (c) 2020-2022 The Decred developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package webapi
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import (
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"errors"
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"github.com/decred/dcrd/chaincfg/v3"
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"github.com/decred/dcrd/hdkeychain/v3"
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"github.com/decred/dcrd/txscript/v4/stdaddr"
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"github.com/decred/slog"
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)
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type addressGenerator struct {
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external *hdkeychain.ExtendedKey
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netParams *chaincfg.Params
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lastUsedIndex uint32
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log slog.Logger
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}
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func newAddressGenerator(xPub string, netParams *chaincfg.Params, lastUsedIdx uint32, log slog.Logger) (*addressGenerator, error) {
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xPubKey, err := hdkeychain.NewKeyFromString(xPub, netParams)
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if err != nil {
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return nil, err
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}
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if xPubKey.IsPrivate() {
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return nil, errors.New("not a public key")
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}
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// Derive the extended key for the external chain.
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external, err := xPubKey.Child(0)
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if err != nil {
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return nil, err
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}
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return &addressGenerator{
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external: external,
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netParams: netParams,
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lastUsedIndex: lastUsedIdx,
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log: log,
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}, nil
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}
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// NextAddress increments the last used address counter and returns a new
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// address. It will skip any address index which causes an ErrInvalidChild.
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// Not safe for concurrent access.
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func (m *addressGenerator) NextAddress() (string, uint32, error) {
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var key *hdkeychain.ExtendedKey
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var err error
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// There is a small chance that generating addresses for a given index can
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// fail with ErrInvalidChild, so loop until we find an index which works.
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// See the hdkeychain.ExtendedKey.Child docs for more info.
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invalidChildren := 0
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for {
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m.lastUsedIndex++
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key, err = m.external.Child(m.lastUsedIndex)
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if err != nil {
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if errors.Is(err, hdkeychain.ErrInvalidChild) {
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invalidChildren++
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m.log.Warnf("Generating address for index %d failed: %v", m.lastUsedIndex, err)
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// If this happens 3 times, something is seriously wrong, so
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// return an error.
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if invalidChildren > 2 {
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return "", 0, errors.New("multiple invalid children generated for key")
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}
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continue
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}
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return "", 0, err
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}
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break
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}
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// Convert to a standard pay-to-pubkey-hash address.
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pkHash := stdaddr.Hash160(key.SerializedPubKey())
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addr, err := stdaddr.NewAddressPubKeyHashEcdsaSecp256k1V0(pkHash, m.netParams)
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if err != nil {
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return "", 0, err
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}
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return addr.String(), m.lastUsedIndex, nil
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}
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