Fix "Trying to access array offset on value of type null"

[dryabov]

Added a check that $previous is not null (i.e. previous token exists)

[GrahamCampbell]

When could it be null?

[dryabov]

It's hard t say, I've found it in log file of a laravel-based project:

[2019-12-31 00:08:44] production.ERROR: Trying to access array offset on value of type null {"exception":"[object] (ErrorException(code: 0): Trying to access array offset on value of type null at _/vendor/egulias/email-validator/EmailValidator/Parser/Parser.php:147)
[stacktrace]
#0 _/vendor/egulias/email-validator/EmailValidator/Parser/Parser.php(147): Illuminate\\Foundation\\Bootstrap\\HandleExceptions->handleError()
#1 _/vendor/egulias/email-validator/EmailValidator/Parser/Parser.php(127): Egulias\\EmailValidator\\Parser\\Parser->escaped()
#2 _/vendor/egulias/email-validator/EmailValidator/Parser/LocalPart.php(57): Egulias\\EmailValidator\\Parser\\Parser->isFWS()
#3 _/vendor/egulias/email-validator/EmailValidator/EmailParser.php(48): Egulias\\EmailValidator\\Parser\\LocalPart->parse()
#4 _/vendor/egulias/email-validator/EmailValidator/Validation/RFCValidation.php(30): Egulias\\EmailValidator\\EmailParser->parse()
#5 _/vendor/egulias/email-validator/EmailValidator/EmailValidator.php(37): Egulias\\EmailValidator\\Validation\\RFCValidation->isValid()
#6 _/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/IdentificationHeader.php(182): Egulias\\EmailValidator\\EmailValidator->isValid()
...

All input emails in isValid look like 'username@mydomain.com' or 'some-hex-id-here@swift.generated'.

[egulias]

That's rare, yes. If "previous" is null, it would have generated an error earlier.
Can you please provide a test that reproduces the error?

[dryabov]

It looks like to be environment-dependent. I've added

if ($previous === null) {
    file_put_contents(__FILE__ . '.log',
                      var_export($this->lexer, true) . "\n\n\n",
                      FILE_APPEND);
}

inside of Egulias\EmailValidator\Parser\Parser::escaped and got following state:

Egulias\EmailValidator\EmailLexer::__set_state(array(
   'charValue' => 
  array (
    '(' => 49,
    ')' => 261,
    '<' => 272,
    '>' => 273,
    '[' => 262,
    ']' => 263,
    ':' => 265,
    ';' => 275,
    '@' => 64,
    '\\' => 92,
    '/' => 278,
    ',' => 274,
    '.' => 46,
    '"' => 34,
    '-' => 264,
    '::' => 266,
    ' ' => 267,
    '	' => 268,
    '
' => 269,
    '
' => 270,
    '
' => 301,
    'IPv6' => 271,
    '{' => 276,
    '}' => 277,
    '' => NULL,
    '\\0' => 0,
  ),
   'hasInvalidTokens' => false,
   'previous' => NULL,
   'input' => 'a2cf7d22c7f734febfa5c6f7105c3062@swift.generated',
   'tokens' => 
  array (
    0 => 
    array (
      'value' => 'a',
      'type' => 300,
      'position' => 0,
    ),
    1 => 
    array (
      'value' => '2',
      'type' => 300,
      'position' => 1,
    ),
    2 => 
    array (
      'value' => 'cf',
      'type' => 300,
      'position' => 2,
    ),
    3 => 
    array (
      'value' => '7',
      'type' => 300,
      'position' => 4,
    ),
    4 => 
    array (
      'value' => 'd',
      'type' => 300,
      'position' => 5,
    ),
    5 => 
    array (
      'value' => '22',
      'type' => 300,
      'position' => 6,
    ),
    6 => 
    array (
      'value' => 'c',
      'type' => 300,
      'position' => 8,
    ),
    7 => 
    array (
      'value' => '7',
      'type' => 300,
      'position' => 9,
    ),
    8 => 
    array (
      'value' => 'f',
      'type' => 300,
      'position' => 10,
    ),
    9 => 
    array (
      'value' => '734',
      'type' => 300,
      'position' => 11,
    ),
    10 => 
    array (
      'value' => 'febfa',
      'type' => 300,
      'position' => 14,
    ),
    11 => 
    array (
      'value' => '5',
      'type' => 300,
      'position' => 19,
    ),
    12 => 
    array (
      'value' => 'c6',
      'type' => 300,
      'position' => 20,
    ),
    13 => 
    array (
      'value' => 'f',
      'type' => 300,
      'position' => 22,
    ),
    14 => 
    array (
      'value' => '7105',
      'type' => 300,
      'position' => 23,
    ),
    15 => 
    array (
      'value' => 'c',
      'type' => 300,
      'position' => 27,
    ),
    16 => 
    array (
      'value' => '3062',
      'type' => 300,
      'position' => 28,
    ),
    17 => 
    array (
      'value' => '@',
      'type' => 64,
      'position' => 32,
    ),
    18 => 
    array (
      'value' => 'swift',
      'type' => 300,
      'position' => 33,
    ),
    19 => 
    array (
      'value' => '.',
      'type' => 46,
      'position' => 38,
    ),
    20 => 
    array (
      'value' => 'generated',
      'type' => 300,
      'position' => 39,
    ),
  ),
   'position' => 2,
   'peek' => 0,
   'lookahead' => 
  array (
    'value' => '2',
    'type' => 300,
    'position' => 1,
  ),
   'token' => 
  array (
    'value' => 'a',
    'type' => 300,
    'position' => 0,
  ),
))

Unfortunately my attempt to reproduce the issue via a simple script has been failed (i.e. no error is triggered):

<?php
error_reporting(-1);
ini_set('display_errors', 1);
require __DIR__ . '/vendor/autoload.php';
$emailValidator = new \Egulias\EmailValidator\EmailValidator();
$emailValidator->isValid(
        'a2cf7d22c7f734febfa5c6f7105c3062@swift.generated',
        new \Egulias\EmailValidator\Validation\RFCValidation()
);

Not sure what I could check additionally.

[dryabov]

According to composer.lock, the installed version is 2.1.6. Maybe the issue has been fixed in 2.1.10, but unfortunately I'm not directly involved into that project and cannot update it to check.

[egulias]

@dryabov maybe you can check Swiftmailer's email generator to see which chars they use and then explore with the lexer test (https://github.com/egulias/EmailValidator/blob/master/Tests/EmailValidator/EmailLexerTest.php#L126) to see if you are able to produce a 'null' element.

[ricardo118]

Ive also started getting this error recently, it was working fine. Maybe related to updating to php7.4?

[egulias]

Thanks @ricardo118 . Are you able to reproduce it with a test?

[cetetesoft]

Ive also started getting this error recently, it was working fine. Maybe related to updating to php7.4?

This is indeed due to upgrading to PHP 7.4. Its first backward incompatible change is:

Trying to use values of type null, bool, int, float or resource as an array (such as $null["key"]) will now generate a notice.

It seems to work fine after replacing line 147 of Parser.php with:
if ($previous && $previous['type'] === EmailLexer::S_BACKSLASH

[egulias]

Hi @cetetesoft good to hear. However, the mistery is under which circumstances $previous can be null. I'd like to have a test reproducing the bug.

[cetetesoft]

@egulias, any email address seems to trigger the error:
(new EmailValidator)->isValid('a@a.a',new RFCValidation);

[egulias]

@cetetesoft however, all test pass in PHP 7.4. I'm investigating the issue.

[egulias]

I'll merge for now and find later how this can happen.