firewalldb+log: add main DB structure

Author: ellemouton

firewalldb/db.go

@@ -0,0 +1,112 @@
+package firewalldb
+
+import (
+	"encoding/binary"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"go.etcd.io/bbolt"
+)
+
+const (
+	// DBFilename is the default filename of the rules' database.
+	DBFilename = "rules.db"
+
+	// dbFilePermission is the default permission the rules' database file
+	// is created with.
+	dbFilePermission = 0600
+
+	// DefaultRulesDBTimeout is the default maximum time we wait for the
+	// db bbolt database to be opened. If the database is already
+	// opened by another process, the unique lock cannot be obtained. With
+	// the timeout we error out after the given time instead of just
+	// blocking for forever.
+	DefaultRulesDBTimeout = 5 * time.Second
+)
+
+var (
+	// byteOrder is the default byte order we'll use for serialization
+	// within the database.
+	byteOrder = binary.BigEndian
+)
+
+// DB is a bolt-backed persistent store.
+type DB struct {
+	*bbolt.DB
+}
+
+// NewDB creates a new bolt database that can be found at the given directory.
+func NewDB(dir, fileName string) (*DB, error) {
+	firstInit := false
+	path := filepath.Join(dir, fileName)
+
+	// If the database file does not exist yet, create its directory.
+	if !fileExists(path) {
+		if err := os.MkdirAll(dir, 0700); err != nil {
+			return nil, err
+		}
+		firstInit = true
+	}
+
+	db, err := initDB(path, firstInit)
+	if err != nil {
+		return nil, err
+	}
+
+	// Attempt to sync the database's current version with the latest known
+	// version available.
+	if err := syncVersions(db); err != nil {
+		return nil, err
+	}
+
+	return &DB{DB: db}, nil
+}
+
+// fileExists reports whether the named file or directory exists.
+func fileExists(path string) bool {
+	if _, err := os.Stat(path); err != nil {
+		if os.IsNotExist(err) {
+			return false
+		}
+	}
+	return true
+}
+
+// initDB initializes all the required top-level buckets for the database.
+func initDB(filepath string, firstInit bool) (*bbolt.DB, error) {
+	db, err := bbolt.Open(filepath, dbFilePermission, &bbolt.Options{
+		Timeout: DefaultRulesDBTimeout,
+	})
+	if err == bbolt.ErrTimeout {
+		return nil, fmt.Errorf("error while trying to open %s: timed "+
+			"out after %v when trying to obtain exclusive lock",
+			filepath, DefaultRulesDBTimeout)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	err = db.Update(func(tx *bbolt.Tx) error {
+		if firstInit {
+			metadataBucket, err := tx.CreateBucketIfNotExists(
+				metadataBucketKey,
+			)
+			if err != nil {
+				return err
+			}
+			err = setDBVersion(metadataBucket, latestDBVersion)
+			if err != nil {
+				return err
+			}
+		}
+
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return db, nil
+}

firewalldb/log.go

@@ -0,0 +1,25 @@
+package firewalldb
+
+import (
+	"github.com/btcsuite/btclog"
+	"github.com/lightningnetwork/lnd/build"
+)
+
+const Subsystem = "FWDB"
+
+// log is a logger that is initialized with no output filters.  This
+// means the package will not perform any logging by default until the caller
+// requests it.
+var log btclog.Logger
+
+// The default amount of logging is none.
+func init() {
+	UseLogger(build.NewSubLogger(Subsystem, nil))
+}
+
+// UseLogger uses a specified Logger to output package logging info.
+// This should be used in preference to SetLogWriter if the caller is also
+// using btclog.
+func UseLogger(logger btclog.Logger) {
+	log = logger
+}

firewalldb/metadata.go

@@ -0,0 +1,121 @@
+package firewalldb
+
+import (
+	"errors"
+	"fmt"
+
+	"go.etcd.io/bbolt"
+)
+
+// migration is a function which takes a prior outdated version of the database
+// instance and mutates the key/bucket structure to arrive at a more up-to-date
+// version of the database.
+type migration func(tx *bbolt.Tx) error
+
+var (
+	// metadataBucketKey stores all the metadata concerning the state of the
+	// database.
+	metadataBucketKey = []byte("metadata")
+
+	// dbVersionKey is the key used for storing/retrieving the current
+	// database version.
+	dbVersionKey = []byte("version")
+
+	// ErrDBReversion is returned when detecting an attempt to revert to a
+	// prior database version.
+	ErrDBReversion = errors.New("cannot revert to prior version")
+
+	// dbVersions is storing all versions of database. If the current
+	// version of the database doesn't match the latest version this list
+	// will be used for retrieving all migration function that are need to
+	// apply to the current db.
+	dbVersions []migration
+
+	latestDBVersion = uint32(len(dbVersions))
+)
+
+// getDBVersion retrieves the current database version.
+func getDBVersion(bucket *bbolt.Bucket) (uint32, error) {
+	versionBytes := bucket.Get(dbVersionKey)
+	if versionBytes == nil {
+		return 0, errors.New("database version not found")
+	}
+	return byteOrder.Uint32(versionBytes), nil
+}
+
+// setDBVersion updates the current database version.
+func setDBVersion(bucket *bbolt.Bucket, version uint32) error {
+	var b [4]byte
+	byteOrder.PutUint32(b[:], version)
+	return bucket.Put(dbVersionKey, b[:])
+}
+
+// getBucket retrieves the bucket with the given key.
+func getBucket(tx *bbolt.Tx, key []byte) (*bbolt.Bucket, error) {
+	bucket := tx.Bucket(key)
+	if bucket == nil {
+		return nil, fmt.Errorf("bucket \"%v\" does not exist",
+			string(key))
+	}
+	return bucket, nil
+}
+
+// syncVersions function is used for safe db version synchronization. It
+// applies migration functions to the current database and recovers the
+// previous state of db if at least one error/panic appeared during migration.
+func syncVersions(db *bbolt.DB) error {
+	var currentVersion uint32
+	err := db.View(func(tx *bbolt.Tx) error {
+		metadata, err := getBucket(tx, metadataBucketKey)
+		if err != nil {
+			return err
+		}
+		currentVersion, err = getDBVersion(metadata)
+		return err
+	})
+	if err != nil {
+		return err
+	}
+
+	log.Infof("Checking for schema update: latest_version=%v, "+
+		"db_version=%v", latestDBVersion, currentVersion)
+
+	switch {
+	// If the database reports a higher version that we are aware of, the
+	// user is probably trying to revert to a prior version of lnd. We fail
+	// here to prevent reversions and unintended corruption.
+	case currentVersion > latestDBVersion:
+		log.Errorf("Refusing to revert from db_version=%d to "+
+			"lower version=%d", currentVersion,
+			latestDBVersion)
+
+		return ErrDBReversion
+
+	// If the current database version matches the latest version number,
+	// then we don't need to perform any migrations.
+	case currentVersion == latestDBVersion:
+		return nil
+	}
+
+	log.Infof("Performing database schema migration")
+
+	// Otherwise, we execute the migrations serially within a single
+	// database transaction to ensure the migration is atomic.
+	return db.Update(func(tx *bbolt.Tx) error {
+		for v := currentVersion; v < latestDBVersion; v++ {
+			log.Infof("Applying migration #%v", v+1)
+
+			migration := dbVersions[v]
+			if err := migration(tx); err != nil {
+				log.Infof("Unable to apply migration #%v", v+1)
+				return err
+			}
+		}
+
+		metadata, err := getBucket(tx, metadataBucketKey)
+		if err != nil {
+			return err
+		}
+		return setDBVersion(metadata, latestDBVersion)
+	})
+}

log.go

@@ -6,6 +6,7 @@ import (
 	"github.com/lightninglabs/lightning-node-connect/mailbox"
 	"github.com/lightninglabs/lightning-terminal/accounts"
 	"github.com/lightninglabs/lightning-terminal/firewall"
+	"github.com/lightninglabs/lightning-terminal/firewalldb"
 	mid "github.com/lightninglabs/lightning-terminal/rpcmiddleware"
 	"github.com/lightninglabs/lightning-terminal/session"
 	"github.com/lightninglabs/loop/loopd"
@@ -69,6 +70,9 @@ func SetupLoggers(root *build.RotatingLogWriter, intercept signal.Interceptor) {
 	lnd.AddSubLogger(
 		root, firewall.Subsystem, intercept, firewall.UseLogger,
 	)
+	lnd.AddSubLogger(
+		root, firewalldb.Subsystem, intercept, firewalldb.UseLogger,
+	)
 
 	// Add daemon loggers to lnd's root logger.
 	faraday.SetupLoggers(root, intercept)