351 lines
9.6 KiB
Go
351 lines
9.6 KiB
Go
package auth
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import (
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"database/sql"
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_ "github.com/mattn/go-sqlite3" // SQLite driver
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"golang.org/x/crypto/bcrypt"
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"regexp"
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)
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const (
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bcryptCost = 11
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)
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// Auther-related queries
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const (
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createAuthTablesQueries = `
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BEGIN;
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CREATE TABLE IF NOT EXISTS user (
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user TEXT NOT NULL PRIMARY KEY,
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pass TEXT NOT NULL,
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role TEXT NOT NULL
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);
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CREATE TABLE IF NOT EXISTS access (
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user TEXT NOT NULL,
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topic TEXT NOT NULL,
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read INT NOT NULL,
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write INT NOT NULL,
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PRIMARY KEY (topic, user)
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);
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CREATE TABLE IF NOT EXISTS schema_version (
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id INT PRIMARY KEY,
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version INT NOT NULL
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);
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COMMIT;
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`
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selectUserQuery = `SELECT pass, role FROM user WHERE user = ?`
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selectTopicPermsQuery = `
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SELECT read, write
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FROM access
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WHERE user IN ('*', ?) AND topic = ?
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ORDER BY user DESC
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`
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)
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// Manager-related queries
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const (
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insertUserQuery = `INSERT INTO user (user, pass, role) VALUES (?, ?, ?)`
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selectUsernamesQuery = `SELECT user FROM user ORDER BY role, user`
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updateUserPassQuery = `UPDATE user SET pass = ? WHERE user = ?`
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updateUserRoleQuery = `UPDATE user SET role = ? WHERE user = ?`
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deleteUserQuery = `DELETE FROM user WHERE user = ?`
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upsertUserAccessQuery = `
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INSERT INTO access (user, topic, read, write)
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VALUES (?, ?, ?, ?)
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ON CONFLICT (user, topic) DO UPDATE SET read=excluded.read, write=excluded.write
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`
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selectUserAccessQuery = `SELECT topic, read, write FROM access WHERE user = ?`
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deleteAllAccessQuery = `DELETE FROM access`
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deleteUserAccessQuery = `DELETE FROM access WHERE user = ?`
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deleteTopicAccessQuery = `DELETE FROM access WHERE user = ? AND topic = ?`
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)
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// SQLiteAuth is an implementation of Auther and Manager. It stores users and access control list
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// in a SQLite database.
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type SQLiteAuth struct {
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db *sql.DB
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defaultRead bool
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defaultWrite bool
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}
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var (
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allowedUsernameRegex = regexp.MustCompile(`^[-_.@a-zA-Z0-9]+$`)
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)
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var _ Auther = (*SQLiteAuth)(nil)
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var _ Manager = (*SQLiteAuth)(nil)
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// NewSQLiteAuth creates a new SQLiteAuth instance
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func NewSQLiteAuth(filename string, defaultRead, defaultWrite bool) (*SQLiteAuth, error) {
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db, err := sql.Open("sqlite3", filename)
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if err != nil {
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return nil, err
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}
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if err := setupNewAuthDB(db); err != nil {
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return nil, err
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}
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return &SQLiteAuth{
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db: db,
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defaultRead: defaultRead,
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defaultWrite: defaultWrite,
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}, nil
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}
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func setupNewAuthDB(db *sql.DB) error {
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if _, err := db.Exec(createAuthTablesQueries); err != nil {
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return err
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}
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// FIXME schema version
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return nil
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}
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// Authenticate checks username and password and returns a user if correct. The method
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// returns in constant-ish time, regardless of whether the user exists or the password is
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// correct or incorrect.
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func (a *SQLiteAuth) Authenticate(username, password string) (*User, error) {
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if username == Everyone {
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return nil, ErrUnauthenticated
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}
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user, err := a.User(username)
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if err != nil {
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bcrypt.CompareHashAndPassword([]byte("$2a$11$eX15DeF27FwAgXt9wqJF0uAUMz74XywJcGBH3kP93pzKYv6ATk2ka"),
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[]byte("intentional slow-down to avoid timing attacks"))
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return nil, ErrUnauthenticated
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}
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if err := bcrypt.CompareHashAndPassword([]byte(user.Hash), []byte(password)); err != nil {
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return nil, ErrUnauthenticated
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}
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return user, nil
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}
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// Authorize returns nil if the given user has access to the given topic using the desired
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// permission. The user param may be nil to signal an anonymous user.
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func (a *SQLiteAuth) Authorize(user *User, topic string, perm Permission) error {
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if user != nil && user.Role == RoleAdmin {
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return nil // Admin can do everything
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}
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username := Everyone
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if user != nil {
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username = user.Name
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}
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// Select the read/write permissions for this user/topic combo. The query may return two
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// rows (one for everyone, and one for the user), but prioritizes the user. The value for
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// user.Name may be empty (= everyone).
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rows, err := a.db.Query(selectTopicPermsQuery, username, topic)
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if err != nil {
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return err
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}
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defer rows.Close()
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if !rows.Next() {
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return a.resolvePerms(a.defaultRead, a.defaultWrite, perm)
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}
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var read, write bool
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if err := rows.Scan(&read, &write); err != nil {
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return err
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} else if err := rows.Err(); err != nil {
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return err
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}
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return a.resolvePerms(read, write, perm)
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}
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func (a *SQLiteAuth) resolvePerms(read, write bool, perm Permission) error {
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if perm == PermissionRead && read {
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return nil
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} else if perm == PermissionWrite && write {
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return nil
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}
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return ErrUnauthorized
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}
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// AddUser adds a user with the given username, password and role. The password should be hashed
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// before it is stored in a persistence layer.
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func (a *SQLiteAuth) AddUser(username, password string, role Role) error {
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if !allowedUsernameRegex.MatchString(username) || !AllowedRole(role) {
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return ErrInvalidArgument
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}
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hash, err := bcrypt.GenerateFromPassword([]byte(password), bcryptCost)
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if err != nil {
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return err
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}
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if _, err = a.db.Exec(insertUserQuery, username, hash, role); err != nil {
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return err
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}
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return nil
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}
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// RemoveUser deletes the user with the given username. The function returns nil on success, even
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// if the user did not exist in the first place.
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func (a *SQLiteAuth) RemoveUser(username string) error {
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if !allowedUsernameRegex.MatchString(username) || username == Everyone {
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return ErrInvalidArgument
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}
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if _, err := a.db.Exec(deleteUserQuery, username); err != nil {
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return err
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}
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if _, err := a.db.Exec(deleteUserAccessQuery, username); err != nil {
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return err
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}
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return nil
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}
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// Users returns a list of users. It always also returns the Everyone user ("*").
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func (a *SQLiteAuth) Users() ([]*User, error) {
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rows, err := a.db.Query(selectUsernamesQuery)
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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usernames := make([]string, 0)
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for rows.Next() {
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var username string
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if err := rows.Scan(&username); err != nil {
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return nil, err
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} else if err := rows.Err(); err != nil {
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return nil, err
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}
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usernames = append(usernames, username)
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}
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rows.Close()
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users := make([]*User, 0)
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for _, username := range usernames {
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user, err := a.User(username)
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if err != nil {
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return nil, err
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}
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users = append(users, user)
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}
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everyone, err := a.everyoneUser()
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if err != nil {
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return nil, err
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}
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users = append(users, everyone)
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return users, nil
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}
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// User returns the user with the given username if it exists, or ErrNotFound otherwise.
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// You may also pass Everyone to retrieve the anonymous user and its Grant list.
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func (a *SQLiteAuth) User(username string) (*User, error) {
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if username == Everyone {
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return a.everyoneUser()
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}
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rows, err := a.db.Query(selectUserQuery, username)
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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var hash, role string
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if !rows.Next() {
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return nil, ErrNotFound
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}
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if err := rows.Scan(&hash, &role); err != nil {
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return nil, err
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} else if err := rows.Err(); err != nil {
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return nil, err
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}
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grants, err := a.readGrants(username)
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if err != nil {
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return nil, err
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}
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return &User{
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Name: username,
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Hash: hash,
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Role: Role(role),
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Grants: grants,
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}, nil
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}
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func (a *SQLiteAuth) everyoneUser() (*User, error) {
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grants, err := a.readGrants(Everyone)
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if err != nil {
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return nil, err
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}
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return &User{
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Name: Everyone,
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Hash: "",
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Role: RoleAnonymous,
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Grants: grants,
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}, nil
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}
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func (a *SQLiteAuth) readGrants(username string) ([]Grant, error) {
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rows, err := a.db.Query(selectUserAccessQuery, username)
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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grants := make([]Grant, 0)
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for rows.Next() {
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var topic string
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var read, write bool
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if err := rows.Scan(&topic, &read, &write); err != nil {
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return nil, err
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} else if err := rows.Err(); err != nil {
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return nil, err
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}
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grants = append(grants, Grant{
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Topic: topic,
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Read: read,
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Write: write,
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})
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}
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return grants, nil
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}
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// ChangePassword changes a user's password
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func (a *SQLiteAuth) ChangePassword(username, password string) error {
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hash, err := bcrypt.GenerateFromPassword([]byte(password), bcryptCost)
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if err != nil {
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return err
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}
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if _, err := a.db.Exec(updateUserPassQuery, hash, username); err != nil {
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return err
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}
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return nil
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}
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// ChangeRole changes a user's role. When a role is changed from RoleUser to RoleAdmin,
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// all existing access control entries (Grant) are removed, since they are no longer needed.
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func (a *SQLiteAuth) ChangeRole(username string, role Role) error {
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if !allowedUsernameRegex.MatchString(username) || !AllowedRole(role) {
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return ErrInvalidArgument
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}
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if _, err := a.db.Exec(updateUserRoleQuery, string(role), username); err != nil {
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return err
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}
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if role == RoleAdmin {
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if _, err := a.db.Exec(deleteUserAccessQuery, username); err != nil {
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return err
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}
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}
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return nil
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}
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// AllowAccess adds or updates an entry in th access control list for a specific user. It controls
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// read/write access to a topic.
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func (a *SQLiteAuth) AllowAccess(username string, topic string, read bool, write bool) error {
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if _, err := a.db.Exec(upsertUserAccessQuery, username, topic, read, write); err != nil {
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return err
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}
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return nil
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}
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// ResetAccess removes an access control list entry for a specific username/topic, or (if topic is
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// empty) for an entire user.
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func (a *SQLiteAuth) ResetAccess(username string, topic string) error {
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if username == "" && topic == "" {
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_, err := a.db.Exec(deleteAllAccessQuery, username)
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return err
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} else if topic == "" {
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_, err := a.db.Exec(deleteUserAccessQuery, username)
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return err
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}
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_, err := a.db.Exec(deleteTopicAccessQuery, username, topic)
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return err
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}
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// DefaultAccess returns the default read/write access if no access control entry matches
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func (a *SQLiteAuth) DefaultAccess() (read bool, write bool) {
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return a.defaultRead, a.defaultWrite
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}
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