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<?php |
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declare(strict_types=1); |
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namespace EmailValidator\Validator\LocalPart; |
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/** |
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* Validates quoted string format of local parts in email addresses |
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*/ |
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class QuotedStringValidator |
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{ |
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/** |
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* Characters that must be escaped in quoted strings |
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*/ |
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private const MUST_ESCAPE = ['"', '\\']; |
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/** |
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* Validates a quoted string local part |
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* |
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* @param string $localPart The quoted string to validate |
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* @return bool True if the quoted string is valid |
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*/ |
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public function validate(string $localPart): bool |
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{ |
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// Must start and end with quotes |
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if (!$this->hasValidQuotes($localPart)) { |
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return false; |
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} |
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// Remove outer quotes for content validation |
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$content = substr($localPart, 1, -1); |
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// Empty quoted strings are valid |
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if ($content === '') { |
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return true; |
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} |
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return $this->validateContent($content); |
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} |
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/** |
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* Checks if a quoted string has valid opening and closing quotes |
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* |
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* @param string $localPart The quoted string to validate |
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* @return bool True if the quotes are valid |
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*/ |
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private function hasValidQuotes(string $localPart): bool |
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{ |
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return substr($localPart, 0, 1) === '"' && substr($localPart, -1) === '"'; |
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} |
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/** |
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* Validates the content of a quoted string |
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* |
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* @param string $content The content to validate (without outer quotes) |
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* @return bool True if the content is valid |
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*/ |
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private function validateContent(string $content): bool |
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{ |
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$length = strlen($content); |
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$i = 0; |
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while ($i < $length) { |
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$char = $content[$i]; |
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$charCode = ord($char); |
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// Handle backslash escapes |
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if ($char === '\\') { |
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// Can't end with a lone backslash |
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if ($i === $length - 1) { |
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return false; |
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} |
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// Next character must be either a quote or backslash |
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$nextChar = $content[$i + 1]; |
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if (!in_array($nextChar, self::MUST_ESCAPE, true)) { |
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return false; |
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} |
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// Skip the escaped character |
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$i += 2; |
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continue; |
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} |
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// Non-printable characters are never allowed (except tab) |
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if (($charCode < 32 || $charCode > 126) && $charCode !== 9) { |
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return false; |
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} |
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// Unescaped quotes are not allowed |
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if ($char === '"') { |
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return false; |
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} |
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$i++; |
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} |
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return true; |
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} |
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} |