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

go to bug id or search bugs for

Bug #23685 fake values returned when OID value is an empty string
Submitted: 2003-05-18 15:47 UTC Modified: 2003-07-18 04:24 UTC
From: s dot zagrodzki at net dot icm dot edu dot pl Assigned:
Status: Closed Package: SNMP related
PHP Version: 4.3.2RC4-dev OS: Linux 2.2
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: s dot zagrodzki at net dot icm dot edu dot pl
New email:
PHP Version: OS:

 

 [2003-05-18 15:47 UTC] s dot zagrodzki at net dot icm dot edu dot pl 
PHP with snmp module. Sample piece of output from snmpwalk utility from ucd-snmp:
$ snmpwalk <router> <community> ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias
...
ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias.3 = lacze do Obs. Astr.
ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias.4 =
ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias.5 = : lacze do Wydz. Zarzadzania
...
(value of ifAlias.4 is an empty string).
Sample script:
<?
$ifAlias = snmprealwalk("<router>", "<community>", "ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias");
print_r($ifAlias);
?>

Output of sample script:
    [ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias.3] => lacze do Obs. Astr.
    [ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias.4] => lacze do Obs. Astr.
    [ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias.5] => : lacze do Wydz. Zarzadz
(ifAlias.4 is now the same as ifAlias.3, not an empty string).

ucd-snmp 4.2.6
router is Cisco 2511 with IOS 11.1(5) (don't suppose it matters, but just in case...)

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2003-07-13 00:11 UTC] sniper@php.net 
Please try using this CVS snapshot:

  http://snaps.php.net/php4-STABLE-latest.tar.gz
 
For Windows:
 
  http://snaps.php.net/win32/php4-win32-STABLE-latest.zip

Some changes have been made lately.
 [2003-07-13 14:49 UTC] harrie@php.net 
I tried this with other variables (I do not have an 
SNMP agent implementing the ifXTable) and cannot 
reproduce it.

Therefore I am thinking that it maybe the SNMP agent
which returns these values and as a result they
show up in PHP. Could you confirm that this is not a
problem with the SNMP agent/router.
 [2003-07-14 02:35 UTC] s dot zagrodzki at net dot icm dot edu dot pl 
this is a part of tcpdump of snmpwalk query:
...
GetResponse(50)  .1.3.6.1.2.1.31.1.1.1.18.3="lacze do Obs. Astr."
GetNextRequest(31)  .1.3.6.1.2.1.31.1.1.1.18.3
GetResponse(31)  .1.3.6.1.2.1.31.1.1.1.18.4=""
GetNextRequest(31)  .1.3.6.1.2.1.31.1.1.1.18.4
GetResponse(59)  .1.3.6.1.2.1.31.1.1.1.18.5=": lacze do Wydz. Zarzadzania"
...
as you can see, snmp agent returns empty value, response length is also correct. And snmpwalk utility also gives
correct results.
 [2003-07-14 03:38 UTC] s dot zagrodzki at net dot icm dot edu dot pl 
I tried using snmp module from 20030714 snapshot - didn't help.
 [2003-07-14 09:44 UTC] s dot zagrodzki at net dot icm dot edu dot pl 
this issue was also mentioned by javierb at gmx dot net in user contributed notes to snmpget() function manual:
http://www.php.net/manual/en/function.snmpget.php
 [2003-07-14 15:15 UTC] harrie@php.net 
Attempted in various ways, but I cannot reproduce this.
Maybe it is a Linux problem, since I do PHP development
on a CYGWIN system.
Neither do I get the same results as the 'user 
contributed note' on snmpget.
 [2003-07-16 01:05 UTC] sniper@php.net 
Please try using this CVS snapshot:

  http://snaps.php.net/php4-STABLE-latest.tar.gz
 
For Windows:
 
  http://snaps.php.net/win32/php4-win32-STABLE-latest.zip

Make sure the snapshot is build later than Jul 16, 2003 05:30!!
 [2003-07-16 02:53 UTC] s dot zagrodzki at net dot icm dot edu dot pl 
tried 20030716-0530 version, didn't help.

I did some more tests:
when I tried snmpwalk()ing ".1.3.6.1.4.1.9.2.2.1.1.28" tree (which is the same as ifAlias, but resides in enterprises.*)
the results were correct. Even more, they had double-quotes
on both sides of the string. tcpdump showed that all responses are exactly the same - same length and value, but PHP displayed them in another way. My guess was that snmpwalk has problems when it _knows_ that the type of received OID value is DisplayString. Then it doesn't put quotes with value.

Simple test - I removed ifAlias definition from IF-MIB.txt
and voila - snmpwalk() returns correct values, but with quotes.

It seems like php-snmp has problem with empty values (and when OID type is unknown, the result is not an empty value, but string consisting of two quotes.
 [2003-07-16 03:58 UTC] sniper@php.net 
I said:

"Make sure the snapshot is build _later_ than Jul 16, 2003 05:30!!"
 [2003-07-18 04:24 UTC] s dot zagrodzki at net dot icm dot edu dot pl 
oh yes. With php4-STABLE-200307180730 the problem is gone.
 
PHP Copyright © 2001-2024 The PHP Group
All rights reserved. 		Last updated: Sat Nov 23 10:01:28 2024 UTC