php.net |  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login

go to bug id or search bugs for

Bug #81220 gethostbyaddr returns binary garbage
Submitted: 2021-07-03 16:52 UTC Modified: 2021-07-11 04:22 UTC
Votes:1
Avg. Score:4.0 ± 0.0
Reproduced:1 of 1 (100.0%)
Same Version:0 (0.0%)
Same OS:0 (0.0%)
From: cyr dot k at me dot com Assigned:
Status: No Feedback Package: Network related
PHP Version: 8.1Git-2021-07-03 (Git) OS: FreeBSD
Private report: No CVE-ID: None
View Developer Edit
Welcome back! If you're the original bug submitter, here's where you can edit the bug or add additional notes.
If you forgot your password, you can retrieve your password here.
Password:
Status:
Package:
Bug Type:
Summary:
From: cyr dot k at me dot com
New email:
PHP Version: OS:

 

 [2021-07-03 16:52 UTC] cyr dot k at me dot com 
Description:
------------
gethostbyaddr("109.197.205.75"), for example, returns four seemingly random bytes string (no, it's not a binary presentation of IPv4 address).
Addresses with proper reverse DNS records still return them as expected, this one IP doesn't have it.

Test script:
---------------
<?php
file_put_contents("/tmp/wtf.bin", gethostbyaddr("109.197.205.75"));
?>


Expected result:
----------------
Should just return the IP if it cannot find a name for it.

Actual result:
--------------
garbage

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2021-07-03 19:26 UTC] danack@php.net
-Status: Open +Status: Feedback
 [2021-07-03 19:26 UTC] danack@php.net 
I couldn't replicate that behaviour. This is likely to be something peculiar to your own system. 

The code is just returning the name returned by the system call: https://github.com/php/php-src/blob/aff365871aec54c9a556d7667f131b8638d20194/ext/standard/dns.c#L204-L206

Can you use the code below, or something similar to dump the actual characters as they might shed some insight:

function showRawCharacters($result) {
    $resultInHex = unpack('H*', $result);
    $resultInHex = $resultInHex[1];
    $resultSeparated = implode(', ', str_split($resultInHex, 2)); //byte safe
    echo $resultSeparated;
}


You could also confirm that the 'garbage' is coming from a system call by running the test script through strace e.g. `strace php debug.php`, to double-check that there isn't something super weird going on.
 [2021-07-11 04:22 UTC] php-bugs at lists dot php dot net 
No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
information that was requested earlier, please do so and
change the status of the bug back to "Re-Opened". Thank you.
 
PHP Copyright © 2001-2025 The PHP Group
All rights reserved. 		Last updated: Wed Nov 05 11:00:02 2025 UTC