Re: [lwip-users] Bridge Port with DHCP

[Shaofeng Cen]

> Please help me to understand why that is a problem.

After I call port_netif->input, the tcpip_thread will call bridgeif_input,

Assuming that the dst->addr[0] &1 == 0.

Here is a part of code in bridgeif_input func, when dst->addr[0] & 1 == 0.

    /* is this for one of the local ports? */

    if (bridgeif_is_local_mac(br, dst)) {

      /* yes, send to cpu port only */

      LWIP_DEBUGF(BRIDGEIF_FW_DEBUG, ("br -> input(%p)\n", (void *)p));

      return br->netif->input(p, br->netif);

    }

    /* get dst port */

    dstports = bridgeif_find_dst_ports(br, dst);

    bridgeif_send_to_ports(br, p, dstports);

    /* no need to send to cpu, flooding is for external ports only */

    /* by  this, we consumed the pbuf */

    pbuf_free(p);

    /* always return ERR_OK here to prevent the caller freeing the pbuf */

    return ERR_OK;

If netif here is a tapif, and br->netif is a bridge_netif.

Before I use it, I call bridgeif_add_port and bridgeif_fdb_add to add port and fdb to the bridge. (I must call these two functions here, because fdb can filter the MAC address and func bridgeif_send_to_ports searchs corresponding port to forward the frame.)

So the func bridgeif_is_local_mac will return 1, func br->netif->input which is tcpip_input will be called, and the func will return.

But I want the network frame pass to bridgeif_send_to_ports, so portif->linkoutput will be called, and the frame will be written to the file descriptor in tap device.

I don’t know if you can understand what I said. My English is not so good.