[Dnsmasq-discuss] dnsmasq is offering ip from different pool

[0zl]

I've encountered this issue as well, I ended up working around it by 
creating bridges that have those vlans as their bridge port. This way 
the bridge stays up to dnsmasq even when I take one of these vlans down.

On 8/4/23 09:24, shashikumar Shashi wrote:
> Hi,
>
> Observing that dnsmasq (version 2.80) is offering DHCP IP to the 
> client from a vlan pool which is in DOWN state.
>
> E.g. If there are 3 dhcp pools
>
> vlan9 (State UP) : Range: 192.168.9.1-192.168.9.254
>
> vlan19 (State UP): Range: 192.168.19.1-192.168.19.254
>
> vlan99 (State DOWN): Range: 192.168.99.1-192.168.99.254
>
> 1) Client on vlan9 gets IP from vlan9 pool
>
> 2) Client moves to vlan19, releases IP
>
> 3) Client on vlan19 requests IP --> dnsmasq offers IP 192.168.99.xx 
> from vlan99 pool (incorrect pool), instead of vlan19 pool.
>
> If the vlan99 is in UP state, then dnsmasq offers the IP from the 
> vlan19 pool (the correct pool).
>
> If dnsmasq is rebuilt by commenting out the following code block from 
> dhcp_reply function, then in the above case, dnsmasq offers IP from 
> the vlan19 pool (the correct pool) even if vlan99 is DOWN.
>
> code block -->
>
> /* guess the netmask for relayed networks */
>
>           if (!(context_tmp->flags & CONTEXT_NETMASK) && 
> context_tmp->netmask.s_addr == 0)
>
>             {
>
>               if (IN_CLASSA(ntohl(context_tmp->start.s_addr)) && 
> IN_CLASSA(ntohl(context_tmp->end.s_addr)))
>
>                 netmask.s_addr = htonl(0xff000000);
>
>               else if (IN_CLASSB(ntohl(context_tmp->start.s_addr)) && 
> IN_CLASSB(ntohl(context_tmp->end.s_addr)))
>
>                 netmask.s_addr = htonl(0xffff0000);
>
>               else if (IN_CLASSC(ntohl(context_tmp->start.s_addr)) && 
> IN_CLASSC(ntohl(context_tmp->end.s_addr)))
>
>                 netmask.s_addr = htonl(0xffffff00);
>
>             }
>
> Has anyone come across such an issue?
>
>
>
> Thanks,
>
> Shashi
>
>
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