The optimal case would be to hack the module source and submit a patch. I'm not familiar with the function, but perhaps it should return "false" or some other value to suggest that the function received bad information. If that is impractical or the function must perform some other important tasks, then I suggest setting a flag and returning that when the time comes. Since you specifically mention that you don't want to change the source, simply setup to catch the die like this

$SIG{__DIE__}=sub{warn 'Illegal ping received!';}
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or something similar before the actual function call. See perlvar for more details on catching signals.

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