[lwip-devel] [bug #48510] DHCP requires ARP

[Jens Nielsen]

URL:
  <http://savannah.nongnu.org/bugs/?48510>

                 Summary: DHCP requires ARP
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: deft
            Submitted on: Thu 14 Jul 2016 09:31:19 AM GMT
                Category: DHCP
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None
            lwIP version: git head

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Details:

Correct me if I'm wrong but there's a snippet in dhcp_start() that
unnecessarily rejects all netif's without ARP


  /* check hwtype of the netif */
  if ((netif->flags & NETIF_FLAG_ETHARP) == 0) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): No ETHARP
netif\n"));
    return ERR_ARG;
  }


I have a non-ethernet interface which may require DHCP (USB MBIM profile), I
have never seen this actually happen but I would still like to implement it.

I suggest two options:
Patch 1: Surround the check with #if DHCP_DOES_ARP_CHECK
Patch 2: Remove the check and only do the check if the netif has
NETIF_FLAG_ETHARP.

Option 2 would allow my netif to coexist with an ethernet one but I guess it
makes the code more confusing and maybe not worth it for a corner case.

I haven't been able to test this properly since I don't really have a
non-ethernet dhcp setup but I can put some effort into it unless someone knows
something I don't and/or think this is a bad idea...



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File Attachments:


-------------------------------------------------------
Date: Thu 14 Jul 2016 09:31:19 AM GMT  Name: dhcp_arp_1.patch  Size: 1004B  
By: deft

<http://savannah.nongnu.org/bugs/download.php?file_id=37870>
-------------------------------------------------------
Date: Thu 14 Jul 2016 09:31:19 AM GMT  Name: dhcp_arp_2.patch  Size: 2kB   By:
deft

<http://savannah.nongnu.org/bugs/download.php?file_id=37871>

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