Parameter validation and other DB manager improvements (#1459)

### Parameter validation

In `statement()` calls of `TenantDatabaseManager`s, use parameter
binding when possible. When that's not possible, validate the parameters
using `validateParameter()` or `validatePassword()`.

Passwords use a less strict allowlist than other parameters (e.g. DB
names), since passwords tend to use more special characters but we can
afford to be more restrictive in the generic `validateParameter()`.

In `SQLiteDatabaseManager`, names of file-based databases are validated
(in `createDatabase`, `deleteDatabase` and `databaseExists`) using a
similar allowlist to the (non-password) parameters in other DB managers,
with an additional character: `.` (this addition is necessary since
file-based SQLite databases end with `.sqlite`).

### DatabaseTenancyBootstrapper - harden() and the lost test file

While checking for more places that could use validation, I realized
that it's possible to update tenant's db_name to the central DB or the
DB of another tenant. Added the `DatabaseTenancyBootstrapper::$harden`
property -- setting it to true prevents tenants from connecting to the
wrong databases (`RuntimeException` is thrown after connecting to the
wrong database).

Also, the DatabaseTenancyBootstrapper test file was ignored while
running tests because it lacked the `Test` suffix. Added the suffix and
fixed the broken `DATABASE_URL` test in the file.

### SQLiteDatabaseManager - respect static $path property in
makeConnectionConfig()

SQLiteDatabaseManager had a bug in `makeConnectionConfig`: the method
didn't respect the static `$path` property, it used `database_path()`
instead. Added a regression test for that. Also recognizing in-memory
SQLite databases (using `isInMemory()`) is more strict now so that
simply having a db_name with `_tenancy_inmemory_` somewhere in the name
doesn't make a file-based database considered in-memory.

### MySQLDatabaseManager - charset and collation defaulting

Creating databases with `null` charsets and collations resulted in a
`QueryException`, since null isn't a valid charset/collation. To solve
that, in the `CREATE DATABASE` statement in MySQLDatabaseManager, only
add charset/collation to the statement if they are not null.

MySQL defaults to the server's charset and collation, so it's safe to
not pass any charset/collation in the `CREATE DATABASE` statement and
let MySQL choose. Also, if e.g. collation is non-null and charset is
null, MySQL will use a charset compatible with the used collation, and
this works both ways.

---------

Co-authored-by: Samuel Stancl <samuel@archte.ch>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

src/Database/Concerns/ValidatesDatabaseParameters.php

@@ -0,0 +1,96 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Stancl\Tenancy\Database\Concerns;
+
+use InvalidArgumentException;
+
+/**
+ * Provides methods to validate database parameters (e.g. database names, usernames, passwords)
+ * before using them in SQL statements (or in file paths in the case of SQLiteDatabaseManager).
+ *
+ * Used where parameters can be provided by users, and where parameter binding cannot be used.
+ *
+ * @see \Stancl\Tenancy\Database\TenantDatabaseManagers\TenantDatabaseManager
+ * @see \Stancl\Tenancy\Database\TenantDatabaseManagers\SQLiteDatabaseManager
+ */
+trait ValidatesDatabaseParameters
+{
+    /**
+     * Characters allowed in parameters.
+     *
+     * Used as the default allowlist in validateParameter(), which validates non-password
+     * parameters such as database names or usernames.
+     *
+     * Since non-password parameters don't need to use as many special characters, we use
+     * a stricter allowlist here.
+     */
+    public static string $allowedParameterCharacters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-';
+
+    /**
+     * Characters allowed in database user passwords.
+     *
+     * The allowlist for passwords is less strict than for other parameters
+     * because it's more common to use more special characters in passwords.
+     */
+    public static string $allowedPasswordCharacters = ' !#$%&()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_abcdefghijklmnopqrstuvwxyz{|}~';
+
+    /**
+     * Ensure that parameter (database name, username, etc.)
+     * only contains allowed characters before being used in SQL statements
+     * (or paths in the case of SQLiteDatabaseManager).
+     *
+     * By default, only the characters in $allowedParameterCharacters are allowed.
+     *
+     * @throws InvalidArgumentException
+     */
+    protected function validateParameter(mixed $parameter, string|null $allowedCharacters = null): void
+    {
+        if (is_null($parameter)) {
+            throw new InvalidArgumentException('Parameter cannot be null.');
+        }
+
+        if (is_numeric($parameter)) {
+            $parameter = (string) $parameter;
+        }
+
+        if (! is_string($parameter)) {
+            throw new InvalidArgumentException('Parameter has to be a string.');
+        }
+
+        if ($parameter === '') {
+            throw new InvalidArgumentException('Parameter cannot be an empty string.');
+        }
+
+        $allowedCharacters ??= static::$allowedParameterCharacters;
+
+        foreach (str_split($parameter) as $character) {
+            if (! str_contains($allowedCharacters, $character)) {
+                throw new InvalidArgumentException("Forbidden character '{$character}' in parameter.");
+            }
+        }
+    }
+
+    /**
+     * Ensure password only contains allowed characters ($allowedPasswordCharacters)
+     * before being used in SQL statements.
+     *
+     * Used in permission controlled managers as a shorthand for calling validateParameter()
+     * with the less strict allowlist to validate database user passwords.
+     *
+     * @throws InvalidArgumentException
+     */
+    protected function validatePassword(string|null $password): void
+    {
+        if (is_null($password)) {
+            throw new InvalidArgumentException('Password cannot be null.');
+        }
+
+        if ($password === '') {
+            throw new InvalidArgumentException('Password cannot be an empty string.');
+        }
+
+        $this->validateParameter($password, allowedCharacters: static::$allowedPasswordCharacters);
+    }
+}