Description: ------------ The Validate_ISPN package relies on _checkControlNumber from Validate - which contains a bug... The 'allow_high' parameter passed from _checkControlNumber to _getControlNumber is 'true' if the last character of the passed in $number is 'X' and false otherwise - this is bad logic. Instead, the 'allow_high' parameter should be 'true' if the modulo is greater than 10 - regardless of what $number is passed in. Note: with correct logic, the 'allow_high' parameter is redundant, as it can be determined within the function itself. A proper-patch with test-cases is available at: http://hexmen.com/code/patches/pear-2879.diff (this bug is probably related to bug 2879, hence the numbering) A one-line patch is below: Index: ../Validate.php =================================================================== RCS file: /repository/pear/Validate/Validate.php,v retrieving revision 1.107 diff -u -r1.107 Validate.php --- ../Validate.php 9 Jan 2007 20:26:00 -0000 1.107 +++ ../Validate.php 23 Feb 2007 16:04:21 -0000 @@ -715,7 +715,7 @@ return false; } $target_digit = substr($number, count($weights), 1); - $control_digit = Validate::_getControlNumber($number, $weights, $modulo, $subtract, $target_digit === 'X'); + $control_digit = Validate::_getControlNumber($number, $weights, $modulo, $subtract, $modulo > 10); if ($control_digit == -1) { return false; Test script: --------------- echo Validate_ISPN::issn('1044-789X') ? "YES\n" : "NO\n"; echo Validate_ISPN::issn('1044-7890') ? "YES\n" : "NO\n"; echo Validate_ISPN::isbn('073571410X') ? "YES\n" : "NO\n"; echo Validate_ISPN::isbn('0735714100') ? "YES\n" : "NO\n"; Expected result: ---------------- YES NO YES NO Actual result: -------------- YES YES YES YES

The valid ISSN number 1044-789X is for Dr Dobbs Journal. As the last-digit is a check-digit, it's unique. So, 1044-7890 is an invalid ISSN number. Similarly, the valid ISBN number is 073571410X, and the invalid one is 0735714100. The book is 'Defensive Design for the Web...' http://www.amazon.com/o/ASIN/073571410X