Bug #68081 [NEW]: checkdnsrr( 'example.com' ) returns `true` when no MX, only CNAME

From: figureonecpr at gmail dot com Operating system: Linux Phoenix 2.6.32 PHP version: master-Git-2014-09-23 (snap) Package: Network related Bug Type: Bug Bug description:checkdnsrr( 'example.com' ) returns true when no MX, only CNAME Description: ------------ Per http://php.net/manual/en/function.checkdnsrr.php, checkdnsrr() defaults to an MX record query when the second argument is not supplied. Regardless of SMTP's implicit MX logic, this function is supposed to return false if $host does not have at least one *explicit* MX in the DNS. However, if the supplied hostname simply has a CNAME record (a good CNAME, one that can be dereferenced to an extant canonical hostname) the function returns true. The bug is seen regardless of whether the canonical hostname itself has an MX record. For example, if you have somehost.example.com CNAME --> example.com A and do checkdnsrr( 'somehost.example.com' ) you will get true. But if you go straight to the canonical A record and do checkdnsrr( 'example.com' ) you will get false. Test script: --------------- // where cname.example.com exists is a CNAME in the DNS pointing to an extant canonical hostname var_dump( checkdnsrr( 'cname.example.com' ) ); Expected result: ---------------- boolean(false) Actual result: -------------- boolean(true) -- Edit bug report at https://bugs.php.net/bug.php?id=68081&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=68081&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=68081&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=68081&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=68081&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=68081&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=68081&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=68081&r=needscript Try newer version: https://bugs.php.net/fix.php?id=68081&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=68081&r=support Expected behavior: https://bugs.php.net/fix.php?id=68081&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=68081&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=68081&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=68081&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=68081&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=68081&r=dst IIS Stability: https://bugs.php.net/fix.php?id=68081&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=68081&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=68081&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=68081&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=68081&r=mysqlcfg