[pkg-ntp-maintainers] Bug#766838: ntpdate runs before network is up

[René Wagner]

tags 766838 + patch
thanks


Dear maintainers,

my testing indicates that there are two distinct problems. First, for 
whatever reason, /etc/network/if-up.d/ntpdate is called with $IFACE = 
--all in addition to legitimate interfaces. This causes a race 
condition: If the $IFACE = --all instance wins, the other instances are 
prevented from doing anything useful.

Secondly, /etc/network/if-up.d/ntpdate is called somewhat early, i.e. 
when the interface is already up but before an IP address has been 
obtained via DHCP.

The attached patch fixes both issues for me. It contains a whitelist of 
interfaces /etc/network/if-up.d/ntpdate should act upon (eth*, wlan*) to 
avoid the bogus $IFACE = --all case. In hindsight, perhaps this should 
be turned into a blacklist containing "--all" only.

The second part of the patch builds upon Hartmut Buhrmester's suggestion 
to insert a "sleep" call, but parses ifconfig output until an IP address 
has been assigned. This part handles the IPv4 case only since I don't 
have an IPv6 network to test with.

I hope you'll find the patch useful!

Cheers,

Rene
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