Re: [Qemu-devel] [PATCH V2 1/2] [SLIRP] Simple ARP table

[Fabien Chouteau <chouteau@adacore.com>]

On 01/08/2011 17:11, Jan Kiszka wrote:
> On 2011-08-01 17:03, Fabien Chouteau wrote:
>> On 30/07/2011 11:19, Jan Kiszka wrote:
>>> On 2011-07-30 11:09, Jan Kiszka wrote:
>>>> On 2011-07-29 19:34, Jan Kiszka wrote:
>>>>> On 2011-07-29 18:25, Fabien Chouteau wrote:
>>>>>> This patch adds a simple ARP table in Slirp and also adds handling of
>>>>>> gratuitous ARP requests.
>>>>>>
>>>>>> Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
>>>>>> ---
>>>>>>  Makefile.objs     |    2 +-
>>>>>>  slirp/arp_table.c |   50 ++++++++++++++++++++++++++++++++++++++++++
>>>>>>  slirp/bootp.c     |   23 ++++++++++++------
>>>>>>  slirp/slirp.c     |   63 +++++++++++++---------------------------------------
>>>>>>  slirp/slirp.h     |   50 +++++++++++++++++++++++++++++++++++++++--
>>>>>>  5 files changed, 129 insertions(+), 59 deletions(-)
>>>>>>  create mode 100644 slirp/arp_table.c
>>>>>>
>>>>>> diff --git a/Makefile.objs b/Makefile.objs
>>>>>> index 6991a9f..0c10557 100644
>>>>>> --- a/Makefile.objs
>>>>>> +++ b/Makefile.objs
>>>>>> @@ -151,7 +151,7 @@ common-obj-y += qemu-timer.o qemu-timer-common.o
>>>>>>
>>>>>>  slirp-obj-y = cksum.o if.o ip_icmp.o ip_input.o ip_output.o
>>>>>>  slirp-obj-y += slirp.o mbuf.o misc.o sbuf.o socket.o tcp_input.o tcp_output.o
>>>>>> -slirp-obj-y += tcp_subr.o tcp_timer.o udp.o bootp.o tftp.o
>>>>>> +slirp-obj-y += tcp_subr.o tcp_timer.o udp.o bootp.o tftp.o arp_table.o
>>>>>>  common-obj-$(CONFIG_SLIRP) += $(addprefix slirp/, $(slirp-obj-y))
>>>>>>
>>>>>>  # xen backend driver support
>>>>>> diff --git a/slirp/arp_table.c b/slirp/arp_table.c
>>>>>> new file mode 100644
>>>>>> index 0000000..5d7404b
>>>>>> --- /dev/null
>>>>>> +++ b/slirp/arp_table.c
>>>>>> @@ -0,0 +1,50 @@
>>>>>> +#include "slirp.h"
>>>>>> +
>>>>>> +void arp_table_add(ArpTable *arptbl,
>>>>>> +                   int       ip_addr,
>>>>>> +                   uint8_t   ethaddr[ETH_ALEN])
>>>>>
>>>>> I still prefer the condensed formatting, but that's a minor nit.
>>
>> OK I'll change it to keep consistent style.
>>
>> Unfortunately, there's nothing on this subject in the CODING_STYLE...
>
> We should add a section on consistency - but I guess that will always
> remain a subjective matter. :)

Indeed, I bet we can find in Qemu an example of every C coding style...

>
>>
>>>>>
>>>>>> +{
>>>>>> +    int i;
>>>>>> +
>>>>>> +    DEBUG_CALL("arp_table_add");
>>>>>> +    DEBUG_ARG("ip = 0x%x", ip_addr);
>>>>>> +    DEBUG_ARGS((dfd, " hw addr = %02x:%02x:%02x:%02x:%02x:%02x\n",
>>>>>> +                ethaddr[0], ethaddr[1], ethaddr[2],
>>>>>> +                ethaddr[3], ethaddr[4], ethaddr[5]));
>>>>>> +
>>>>>> +    /* Search for an entry */
>>>>>> +    for (i = 0; i < ARP_TABLE_SIZE && arptbl->table[i].ar_sip != 0; i++) {
>>>>>
>>>>> Missed that on round #1: Why treating 0.0.0.0 special? If ip_addr can be
>>>>> zero, the current logic will append every "update" of that address as a
>>>>> new entry.
>>
>> Isn't 0.0.0.0 a reserved address? I think it's safe to use it here.
>
> Actually, the whole 0.0.0.0/8 is source-only, ie. it should never show
> up in the ARP table.
>

Great, so I will just prevent insertion and search of 0.0.0.0/8 addresses.

Regards,

-- 
Fabien Chouteau