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refactor: optimize prepQuotedPrintable() with hash lookup and int-length tracking #10344

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refactor: optimize prepQuotedPrintable() with hash lookup and int-length tracking #10344

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refactor: optimize prepQuotedPrintable() with O(1) lookup, int-length…
gr8man Jun 28, 2026
ce158a2
cs-fix
gr8man Jun 28, 2026
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144 changes: 24 additions & 120 deletions system/Email/Email.php
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Original file line number Diff line number Diff line change
Expand Up @@ -197,7 +197,7 @@ class Email
*
* @see http://www.ietf.org/rfc/rfc822.txt
*
* @var "\r\n"|"n"
* @var "\n"|"\r\n"
*/
public $CRLF = "\r\n";

Expand Down Expand Up @@ -1335,156 +1335,60 @@ protected function appendAttachments(&$body, $boundary, $multipart = null)
*/
protected function prepQuotedPrintable($str)
{
// ASCII code numbers for "safe" characters that can always be
// used literally, without encoding, as described in RFC 2049.
// http://www.ietf.org/rfc/rfc2049.txt
static $asciiSafeChars = [
// ' ( ) + , - . / : = ?
39,
40,
41,
43,
44,
45,
46,
47,
58,
61,
63,
// numbers
48,
49,
50,
51,
52,
53,
54,
55,
56,
57,
// upper-case letters
65,
66,
67,
68,
69,
70,
71,
72,
73,
74,
75,
76,
77,
78,
79,
80,
81,
82,
83,
84,
85,
86,
87,
88,
89,
90,
// lower-case letters
97,
98,
99,
100,
101,
102,
103,
104,
105,
106,
107,
108,
109,
110,
111,
112,
113,
114,
115,
116,
117,
118,
119,
120,
121,
122,
];

// We are intentionally wrapping so mail servers will encode characters
// properly and MUAs will behave, so {unwrap} must go!
$str = str_replace(['{unwrap}', '{/unwrap}'], '', $str);

// RFC 2045 specifies CRLF as "\r\n".
// However, many developers choose to override that and violate
// the RFC rules due to (apparently) a bug in MS Exchange,
// which only works with "\n".
if ($this->CRLF === "\r\n") {
return quoted_printable_encode($str);
}

// Reduce multiple spaces & remove nulls
$str = preg_replace(['| +|', '/\x00+/'], [' ', ''], $str);

// Standardize newlines
if (str_contains($str, "\r")) {
$str = str_replace(["\r\n", "\r"], "\n", $str);
}

$escape = '=';
static $asciiSafeChars;
if ($asciiSafeChars === null) {
$safeChars = [39, 40, 41, 43, 44, 45, 46, 47, 58, 61, 63];
$safeChars = array_merge($safeChars, range(48, 57), range(65, 90), range(97, 122));
$asciiSafeChars = array_fill_keys($safeChars, true);
}

$output = '';

foreach (explode("\n", $str) as $line) {
$length = static::strlen($line);
$temp = '';
$length = static::strlen($line);
$temp = '';
$tempLen = 0;

// Loop through each character in the line to add soft-wrap
// characters at the end of a line " =\r\n" and add the newly
// processed line(s) to the output (see comment on $crlf class property)
for ($i = 0; $i < $length; $i++) {
// Grab the next character
$char = $line[$i];
$ascii = ord($char);
$char = $line[$i];
$ascii = ord($char);
$charLen = 1;

// Convert spaces and tabs but only if it's the end of the line
if ($ascii === 32 || $ascii === 9) {
if ($i === ($length - 1)) {
$char = $escape . sprintf('%02s', dechex($ascii));
$char = sprintf('=%02X', $ascii);
$charLen = 3;
}
}
// DO NOT move this below the $ascii_safe_chars line!
//
// = (equals) signs are allowed by RFC2049, but must be encoded
// as they are the encoding delimiter!
elseif ($ascii === 61) {
$char = $escape . strtoupper(sprintf('%02s', dechex($ascii))); // =3D
} elseif (! in_array($ascii, $asciiSafeChars, true)) {
$char = $escape . strtoupper(sprintf('%02s', dechex($ascii)));
} elseif ($ascii === 61 || ! isset($asciiSafeChars[$ascii])) {
$char = sprintf('=%02X', $ascii);
$charLen = 3;
}

// If we're at the character limit, add the line to the output,
// reset our temp variable, and keep on chuggin'
if ((static::strlen($temp) + static::strlen($char)) >= 76) {
$output .= $temp . $escape . $this->CRLF;
$temp = '';
if (($tempLen + $charLen) >= 76) {
$output .= $temp . '=' . $this->CRLF;
$temp = '';
$tempLen = 0;
}

// Add the character to our temporary line
$temp .= $char;
$tempLen += $charLen;
}

// Add our completed line to the output
$output .= $temp . $this->CRLF;
}

// get rid of extra CRLF tacked onto the end
return static::substr($output, 0, static::strlen($this->CRLF) * -1);
}

Expand Down
107 changes: 107 additions & 0 deletions tests/system/Email/EmailTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -302,4 +302,111 @@ public function testGetHostnameFallsBackToGethostnameFunction(): void

$this->assertSame(gethostname(), $getHostname());
}

#[DataProvider('providePrepQuotedPrintableWithLfCrlf')]
public function testPrepQuotedPrintableWithLfCrlf(string $input, string $expected): void
{
$email = new Email();
$email->CRLF = "\n";
$prepQP = self::getPrivateMethodInvoker($email, 'prepQuotedPrintable');

$this->assertSame($expected, $prepQP($input));
}

/**
* @return iterable<string, array{string, string}>
*/
public static function providePrepQuotedPrintableWithLfCrlf(): iterable
{
return [
'empty string' => ['', ''],
'safe ascii only' => ['hello world', 'hello world'],
'safe chars only' => ['abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789(),-./:?', 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789(),-./:?'],
'unsafe char encoded' => ["a\x01b", 'a=01b'],
'trailing space encoded' => ["hello \nworld", "hello=20\nworld"],
'trailing tab encoded' => ["hello\t\nworld", "hello=09\nworld"],
'equals sign encoded as =3D' => ['a=b', 'a=3Db'],
'multiple spaces reduced' => ['a b', 'a b'],
'null bytes removed' => ["a\x00b", 'ab'],
'unwrap tags removed' => ['{unwrap}secret{/unwrap}', 'secret'],
'single line' => ['test', 'test'],
'two lines' => ["line1\nline2", "line1\nline2"],
'three lines trailing empty' => ["line1\nline2\n", "line1\nline2\n"],
];
}

public function testPrepQuotedPrintableWithCrlfNative(): void
{
$email = new Email();
$email->CRLF = "\r\n";
$prepQP = self::getPrivateMethodInvoker($email, 'prepQuotedPrintable');

$result = $prepQP('test');

$this->assertSame(quoted_printable_encode('test'), $result);
}

public function testPrepQuotedPrintableSoftLineBreak(): void
{
$email = new Email();
$email->CRLF = "\n";
$prepQP = self::getPrivateMethodInvoker($email, 'prepQuotedPrintable');

// 76 'a' chars fit in one line; add 2 more 'b' chars and they soft-wrap
// After reduction: no trailing spaces, just safe chars
$input = str_repeat('a', 76) . 'bb';
$result = $prepQP($input);

$this->assertStringContainsString("=\n", $result, 'Soft line break must be present');
$this->assertStringNotContainsString("\r\n", $result, 'Custom CRLF must not contain \\r');
}

public function testPrepQuotedPrintableSoftBreakAfterEncodedChar(): void
{
$email = new Email();
$email->CRLF = "\n";
$prepQP = self::getPrivateMethodInvoker($email, 'prepQuotedPrintable');

// 74 safe chars + 1 encoded (=3D = 3 bytes) = 77 → must break before encoded
$input = str_repeat('a', 74) . '=';
$result = $prepQP($input);

$this->assertSame(str_repeat('a', 74) . "=\n=3D", $result);
}

public function testPrepQuotedPrintableHardLineBreakNoInternalSpaceReduction(): void
{
$email = new Email();
$email->CRLF = "\n";
$prepQP = self::getPrivateMethodInvoker($email, 'prepQuotedPrintable');

// Spaces not at end of line must be left as-is
$this->assertSame('a b', $prepQP('a b'));
}

public function testPrepQuotedPrintableMixedContent(): void
{
$email = new Email();
$email->CRLF = "\n";
$prepQP = self::getPrivateMethodInvoker($email, 'prepQuotedPrintable');

$input = "Hello, World!\nline ends with tab\t\n=special chars: \x01\x02";
$result = $prepQP($input);

$this->assertStringContainsString('Hello, World=21', $result);
$this->assertStringContainsString('=09', $result);
$this->assertStringContainsString('=3D', $result);
$this->assertStringContainsString('=01', $result);
$this->assertStringContainsString('=02', $result);
}

public function testPrepQuotedPrintableUnwrapRemovesTagsOnly(): void
{
$email = new Email();
$email->CRLF = "\n";
$prepQP = self::getPrivateMethodInvoker($email, 'prepQuotedPrintable');

$this->assertSame('keep =7Bbraces=7D', $prepQP('keep {braces}'));
$this->assertSame('keep (parentheses)', $prepQP('keep (parentheses)'));
}
}
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