[lwip-users] Question about DHCP server and 2nd layer delivery

[Xiaomin Lin]

Hi,

 

My name is Xiaomin Lin, and I am very new to LwIP.

I am writing a DHCP server with LwIP. It seems there is only DHCP client code included in LwIP.

I got some question when writing DHCP server:

 

1.       Is there already DHCP server related code somewhere in LwIP? Then I don’t need to reinvent the wheel.

2.       DHCP clients in my project also uses LwIP. In LwIP DHCP client code, it set the “broadcast flag” to false. It suppose DHCP server can deliver DHCP offer and DHCP ack back to client via unicast but not broadcast. But that means DHCP server need to have 2^nd layer delivery capability.

3.       I want to use 2^nd layer delivery to send back DHCP offer and DHCP ack but I found ip.c in LwIP does not really support 2^nd layer delivery. Lwip ip.c will reset target MAC address to broadcasting when it finds target IP is IPADDR_ANY or IPADDR_BROADCAST. I believe 2^nd layer delivery need to set a preferred MAC with IP address any.

4.       Is there already 2^nd layer delivery support in LwIP somewhere, or my understanding of 2^nd layer delivery is wrong?

5.       It is not too hard to add 2^nd layer delivery support interface in ip.c. If my idea is not wrong, can I contribute to add 2^nd layer delivery support in ip.c of LwIP? How?

 

Thanks!

 

Best wishes!

 

Xiaomin Lin

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