Bug #73518 [NEW]: gethostbyaddr unnecessarily attempts to resolve the domain name back to IP addr

From: teo8976 at gmail dot com Operating system: linux PHP version: 5.6.28 Package: HTTP related Bug Type: Bug Bug description:gethostbyaddr unnecessarily attempts to resolve the domain name back to IP addr Description: ------------ When you call gethostbyaddr($someip), it does 2 DNS lookups: 1 - looks up the IP to find the corresponding domain name, i.e. does its job 2 - then looks up the domain name, as if it needed to find the corresponding IP address The second is completely unnecessary, especially considering that, if it times out, it nonetheless returns the host name found at step 1 (if, in this case, it returned false or the IP address, one may perhaps argue that it makes sense in order to verify that the host name is correct or something). Test script: --------------- <?php echo gethostbyaddr('95.232.181.106'); Expected result: ---------------- should immediately print: host106-181-dynamic.232-95-r.retail.telecomitalia.it At http://mxtoolbox.com/SuperTool.aspx?action=ptr%3a95.232.181.106&run=toolpage# you can verify that it takes a fraction of a second to do the reverse lookup Actual result: -------------- From most servers, it takes more than 15 seconds (I guess it depends on how long it takes for the DNS resolver to time out), and then it prints the expected domain name. Apparently, there is something wrong with this domain which prevents the name from being resolved to an IP: http://mxtoolbox.com/SuperTool.aspx?action=a%3ahost106-181-dynamic.232-95-r.retail.telecomitalia.it&run=toolpage However, as explained above, the name->IP lookup is completely unnecessary. -- Edit bug report at https://bugs.php.net/bug.php?id=73518&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=73518&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=73518&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=73518&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=73518&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=73518&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=73518&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=73518&r=needscript Try newer version: https://bugs.php.net/fix.php?id=73518&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=73518&r=support Expected behavior: https://bugs.php.net/fix.php?id=73518&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=73518&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=73518&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=73518&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=73518&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=73518&r=dst IIS Stability: https://bugs.php.net/fix.php?id=73518&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=73518&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=73518&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=73518&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=73518&r=mysqlcfg