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udhcp: make arpping code resistant to time jumps

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2012-04-17 17:10:31 +02:00
parent 53772869bc
commit 6500d123d0
1 changed files with 7 additions and 2 deletions
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9
networking/udhcp/arpping.c
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@ -118,8 +118,13 @@ int FAST_FUNC arpping(uint32_t test_nip,
break;
}
}
timeout_ms -= (unsigned)monotonic_ms() - prevTime;
} while (timeout_ms > 0);
timeout_ms -= (unsigned)monotonic_ms() - prevTime + 1;
/* We used to check "timeout_ms > 0", but
* this is more under/overflow-resistant
* (people did see overflows here when system time jumps):
*/
} while ((unsigned)timeout_ms <= 2000);
ret:
close(s);