MimePart: fixed not escaped header before encoded into utf-8

src/Mail/MimePart.php

@@ -279,12 +279,21 @@ public function getEncodedMessage(): string
 	 */
 	private static function encodeSequence(string $s, int &$offset = 0, ?int $type = null): string
 	{
+		$escape = static function (string $s): string {
+			// RFC 2822 atext except =
+			if (preg_match('#[^ a-zA-Z0-9!\#$%&\'*+/?^_`{|}~-]#', $s) === 1) {
+				return sprintf('"%s"', addcslashes($s, '"\\'));
+			}
+
+			return $s;
+		};
+
 		if (
 			(strlen($s) < self::LineLength - 3) && // 3 is tab + quotes
 			strspn($s, "!\"#$%&\\'()*+,-./0123456789:;<>@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^`abcdefghijklmnopqrstuvwxyz{|}~=? _\r\n\t") === strlen($s)
 		) {
-			if ($type && preg_match('#[^ a-zA-Z0-9!\#$%&\'*+/?^_`{|}~-]#', $s)) { // RFC 2822 atext except =
-				return self::append('"' . addcslashes($s, '"\\') . '"', $offset);
+			if ($type !== null) {
+				$s = $escape($s);
 			}
 
 			return self::append($s, $offset);
@@ -296,6 +305,10 @@ private static function encodeSequence(string $s, int &$offset = 0, ?int $type =
 			$offset = 1;
 		}
 
+		if ($type !== null) {
+			$s = $escape($s);
+		}
+
 		$s = iconv_mime_encode(str_repeat(' ', $old = $offset), $s, [
 			'scheme' => 'B', // Q is broken
 			'input-charset' => 'UTF-8',

tests/Mail/Mail.headers.002.phpt

@@ -17,7 +17,7 @@ require __DIR__ . '/Mail.php';
 
 $mail = new Message;
 
-$mail->setFrom('John Doe <[email protected]>');
+$mail->setFrom('Kdo uteče, obědvá <[email protected]>');
 
 $mail->addTo('Lady Jane <[email protected]>');
 $mail->addCc('[email protected]');
@@ -37,7 +37,7 @@ Assert::match(<<<'EOD'
 	MIME-Version: 1.0
 	X-Mailer: Nette Framework
 	Date: %a%
-	From: John Doe <[email protected]>
+	From: =?UTF-8?B?IktkbyB1dGXEjWUsIG9ixJtkdsOhIg==?= <[email protected]>
 	To: Lady Jane <[email protected]>
 	Cc: [email protected]
 	Bcc: [email protected]