[lwip-users] Bridge Port with DHCP

[sjtu]

Hi
I am trying to use lwip bridge to replace vswitch which is implemented by 
myself.
And I follow the usage here 
http://www.nongnu.org/lwip/2_1_x/group__bridgeif.html to use lwip bridge.

Now I just add one port to the bridge, I use port_netif->input() func to submit 
the data.

When I use DHCP to get an IP, the network frame will be forwarded to 
bridge_netif->input func which is reasonable. But when the `tcpip_thread` calls 
`msg->msg.inp.input_fn(msg->msg.inp.p, msg->msg.inp.netif)`, the netif inside 
is `bridge_netif`.
The func call chain is like `ethernet_input` -> `ip4_input`

In `ip4_input`, `ip_data.current_input_netif` will be set to bridge_netif, 
which will be used in `dhcp_recv`.
`dhcp_recv` will call `ip_current_input_netif` to get a netif, and read dhcp 
data from it.
This is the key problem, when I calls `ip4_input`, the 
`ip_data.current_input_netif` will be set to `bridge_netif`, so I cannot use 
port_netif’s dhcp data to get IP.
Now I can assign IP to the bridge_netif, not the port_netif.

How can I assign IP per port by DHCP?