test a connection to a network device using snmp - php

Question

I have this code to retrieve some countervalues of a copymachine.
foreach($sett as $key => $value){
if (intval(str_replace("INTEGER: ","",snmpget($ip, "public", $base.$value["MIB"])))) {
$c = intval(str_replace("INTEGER: ","",snmpget($ip, "public", $base.$value["MIB"])));
$error = false;
}
else {
$c = 0;
$error = true;
}
$counters = array_push_assoc($counters,ucwords($key),array("total" => $c, "code" => $value["code"]));
}
everything works like a charm but the only thing that is the problem is when a machine is down en the code cannot make an SNMPGET, the whole script fails.
First I want to check if the connection to the device is alive and then retrieve the counters with SNMPGET
Is there any solution you guys can offer me?
thx

Answer 1

The snmpget() function returns FALSE if it fails to retrieve the object.
See docs: http://www.php.net/manual/en/function.snmpget.php
You should do a check for this within your code, for example:
try
{
foreach($sett as $key => $value){
$sntpReturn = snmpget($ip, "public", $base.$value["MIB"]);
if ($sntpReturn === false)
{
// Do something to handle failed SNTP request.
throw new Exception("Failed to execute the SNTP request to the machine.");
}
else
{
if (intval(str_replace("INTEGER: ","", $sntpReturn))) {
$c = intval(str_replace("INTEGER: ","",snmpget($ip, "public", $base.$value["MIB"])));
$error = false;
}
else {
$c = 0;
$error = true;
}
$counters = array_push_assoc($counters,ucwords($key),array("total" => $c, "code" => $value["code"]));
}
}
catch (Exception $e)
{
// Handle the exception, maybe kill the script because it failed?
}