On Wed, Nov 5, 2014 at 9:33 PM, Michael McTernan
<[email protected]> wrote:
> Hi All,
>
> There's a FIXME in udhcpd which describes a small corner case when saved
> leases are read and honoured even if the IP or MAC of that lease overlaps a
> static_lease from the config file. I found that because of this, after
> updating config and restarting udhcpd, a client which already had a lease can
> continue to renew that lease instead of either getting the IP specified in a
> new 'static_lease' config item, or being nak'd and assigned a new free IP.
>
> Following is a small patch which removes the FIXME and adds a check to
> discard saved lease records if they would conflict with a static_lease from
> the config file.
>
> In my configuration, this added 48 bytes to the stripped executable. I
> tested it by defining a /24 subnet and adding static_lease records for all
> but 1 on the available IP addresses, and then moving that 1 available IP
> around while reconnecting a single client. After the patch, verbose logging
> and Wireshark show NAK and then offering of the single free address, with the
> client having it's IP updated each time ipconfig /renew is issued.
>
> Please consider for inclusion to busybox.
>
> + // Check if there is a different static lease for
> this IP or MAC
> + slnip =
> get_static_nip_by_mac(server_config.static_leases, lease.lease_mac);
> + if ((slnip != 0 && slnip != lease.lease_nip)
> + || (slnip == 0 &&
> is_nip_reserved(server_config.static_leases, lease.lease_nip)))
> + continue;
> +
I'm going with a somewhat different version:
+ /* Check if there is a different static lease
for this IP or MAC */
+ static_nip =
get_static_nip_by_mac(server_config.static_leases, lease.lease_mac);
+ if (static_nip) {
+ /* NB: we do not add lease even if
static_nip == lease.lease_nip.
+ */
+ continue;
+ }
+ if
(is_nip_reserved(server_config.static_leases, lease.lease_nip))
+ continue;
Thanks!
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