From b97681bd96502d81ec6e5277b7e9f88e47e3393b Mon Sep 17 00:00:00 2001
From: Ken Sedgwick <ken@bonsai.com>
Date: Wed, 25 Mar 2020 16:03:16 -0700
Subject: [PATCH] Added Wallet and Loader watching-only wallet creation.

---
 wallet/loader.go            | 36 +++++++++++++++++++----
 wallet/wallet.go            | 57 +++++++++++++++++++++++++------------
 wallet/watchingonly_test.go | 34 ++++++++++++++++++++++
 3 files changed, 104 insertions(+), 23 deletions(-)
 create mode 100644 wallet/watchingonly_test.go

diff --git a/wallet/loader.go b/wallet/loader.go
index 5ae807e3fc..9cb77341b5 100644
--- a/wallet/loader.go
+++ b/wallet/loader.go
@@ -100,6 +100,25 @@ func (l *Loader) RunAfterLoad(fn func(*Wallet)) {
 func (l *Loader) CreateNewWallet(pubPassphrase, privPassphrase, seed []byte,
 	bday time.Time) (*Wallet, error) {
 
+	return l.createNewWalletInternal(
+		pubPassphrase, privPassphrase, seed, bday, false,
+	)
+}
+
+// CreateNewWatchingOnlyWallet creates a new wallet using the provided
+// public passphrase.  No seed or private passphrase may be provided
+// since the wallet is watching-only.
+func (l *Loader) CreateNewWatchingOnlyWallet(pubPassphrase []byte,
+	bday time.Time) (*Wallet, error) {
+
+	return l.createNewWalletInternal(
+		pubPassphrase, nil, nil, bday, true,
+	)
+}
+
+func (l *Loader) createNewWalletInternal(pubPassphrase, privPassphrase,
+	seed []byte, bday time.Time, isWatchingOnly bool) (*Wallet, error) {
+
 	defer l.mu.Unlock()
 	l.mu.Lock()
 
@@ -127,11 +146,18 @@ func (l *Loader) CreateNewWallet(pubPassphrase, privPassphrase, seed []byte,
 	}
 
 	// Initialize the newly created database for the wallet before opening.
-	err = Create(
-		db, pubPassphrase, privPassphrase, seed, l.chainParams, bday,
-	)
-	if err != nil {
-		return nil, err
+	if isWatchingOnly {
+		err = CreateWatchingOnly(db, pubPassphrase, l.chainParams, bday)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		err = Create(
+			db, pubPassphrase, privPassphrase, seed, l.chainParams, bday,
+		)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	// Open the newly-created wallet.
diff --git a/wallet/wallet.go b/wallet/wallet.go
index a3e092cb3d..a00588a99f 100644
--- a/wallet/wallet.go
+++ b/wallet/wallet.go
@@ -3620,23 +3620,45 @@ func (w *Wallet) Database() walletdb.DB {
 // Create creates an new wallet, writing it to an empty database.  If the passed
 // seed is non-nil, it is used.  Otherwise, a secure random seed of the
 // recommended length is generated.
-func Create(db walletdb.DB, pubPass, privPass, seed []byte, params *chaincfg.Params,
-	birthday time.Time) error {
-
-	// If a seed was provided, ensure that it is of valid length. Otherwise,
-	// we generate a random seed for the wallet with the recommended seed
-	// length.
-	if seed == nil {
-		hdSeed, err := hdkeychain.GenerateSeed(
-			hdkeychain.RecommendedSeedLen)
-		if err != nil {
-			return err
+func Create(db walletdb.DB, pubPass, privPass, seed []byte,
+	params *chaincfg.Params, birthday time.Time) error {
+
+	return createInternal(
+		db, pubPass, privPass, seed, params, birthday, false,
+	)
+}
+
+// CreateWatchingOnly creates an new watch-only wallet, writing it to
+// an empty database. No seed can be provided as this wallet will be
+// watching only.  Likewise no private passphrase may be provided
+// either.
+func CreateWatchingOnly(db walletdb.DB, pubPass []byte,
+	params *chaincfg.Params, birthday time.Time) error {
+
+	return createInternal(
+		db, pubPass, nil, nil, params, birthday, true,
+	)
+}
+
+func createInternal(db walletdb.DB, pubPass, privPass, seed []byte,
+	params *chaincfg.Params, birthday time.Time, isWatchingOnly bool) error {
+
+	if !isWatchingOnly {
+		// If a seed was provided, ensure that it is of valid length. Otherwise,
+		// we generate a random seed for the wallet with the recommended seed
+		// length.
+		if seed == nil {
+			hdSeed, err := hdkeychain.GenerateSeed(
+				hdkeychain.RecommendedSeedLen)
+			if err != nil {
+				return err
+			}
+			seed = hdSeed
+		}
+		if len(seed) < hdkeychain.MinSeedBytes ||
+			len(seed) > hdkeychain.MaxSeedBytes {
+			return hdkeychain.ErrInvalidSeedLen
 		}
-		seed = hdSeed
-	}
-	if len(seed) < hdkeychain.MinSeedBytes ||
-		len(seed) > hdkeychain.MaxSeedBytes {
-		return hdkeychain.ErrInvalidSeedLen
 	}
 
 	return walletdb.Update(db, func(tx walletdb.ReadWriteTx) error {
@@ -3650,8 +3672,7 @@ func Create(db walletdb.DB, pubPass, privPass, seed []byte, params *chaincfg.Par
 		}
 
 		err = waddrmgr.Create(
-			addrmgrNs, seed, pubPass, privPass, params, nil,
-			birthday,
+			addrmgrNs, seed, pubPass, privPass, params, nil, birthday,
 		)
 		if err != nil {
 			return err
diff --git a/wallet/watchingonly_test.go b/wallet/watchingonly_test.go
new file mode 100644
index 0000000000..f7846b1cc2
--- /dev/null
+++ b/wallet/watchingonly_test.go
@@ -0,0 +1,34 @@
+// Copyright (c) 2018 The btcsuite developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package wallet
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	_ "github.com/btcsuite/btcwallet/walletdb/bdb"
+)
+
+// TestCreateWatchingOnly checks that we can construct a watching-only
+// wallet.
+func TestCreateWatchingOnly(t *testing.T) {
+	// Set up a wallet.
+	dir, err := ioutil.TempDir("", "watchingonly_test")
+	if err != nil {
+		t.Fatalf("Failed to create db dir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	pubPass := []byte("hello")
+
+	loader := NewLoader(&chaincfg.TestNet3Params, dir, true, 250)
+	_, err = loader.CreateNewWatchingOnlyWallet(pubPass, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create wallet: %v", err)
+	}
+}