[Nagiosplug-devel] [ nagiosplug-Bugs-1894850 ] check_ping: incorrectly parses ping6 output

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Bugs item #1894850, was opened at 2008-02-16 10:57
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Category: Parsing problem
Group: Release (specify)
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Matej Vela (vela)
Assigned to: Nobody/Anonymous (nobody)
Summary: check_ping: incorrectly parses ping6 output

Initial Comment:
Plugin Version:
    1.4.11, HEAD
Plugin Name:
    check_ping
Plugin Commandline showing issues:
    check_ping -H [invalid-ipv6-address] -w 5000,100% -c 5000,100% -p 1
Operating System:
    Debian GNU/Linux 4.0 (etch)

Debian's ping6 may produce output in the following format:

    3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2009ms

There's a corresponding pattern in check_ping.c:450:

    "%*d packets transmitted, %*d received, +%*d errors, %d%% packet loss"

but the pattern in check_ping.c:448 matches first:

    "%*d packets transmitted, %*d received, %d%% loss, time"

because sscanf interprets "+3" as a match for "%d".  Although the rest
of the pattern doesn't match, the number of successful assignments
(and thus the return value of sscanf) is still 1.

A simple way to make sure the whole pattern matches is to add a "%n"
specifier at the end, which will assign the number of characters
matched by that point.  (The same trick is used in check_http.c.)
There seems to be some confusion whether "%n" affects the return value
of sscanf, so it's safer to check the assigned number of characters.

Patch attached.


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