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

[Jan Kiszka <jan.kiszka@web.de>]

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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. :)

> 
>>>>
>>>>> +{
>>>>> +    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.

Jan


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