Re: [Qemu-devel] [PATCH v2 4/4] linux-user: manage bind with a socket of SOCK_PACKET type.

[Laurent Vivier <laurent@vivier.eu>]

Le 28/10/2015 20:20, Peter Maydell a écrit :
> On 28 October 2015 at 19:13, Laurent Vivier <laurent@vivier.eu> wrote:
>> This is obsolete, but if we want to use dhcp with an old distro (like debian
>> etch), we need it. Some users (like dhclient) use SOCK_PACKET with AF_PACKET
>> and the kernel allows that.
>>
>> packet(7)
>>
>>   In Linux 2.0, the only way to  get  a  packet  socket  was  by calling
>>   socket(AF_INET,  SOCK_PACKET,  protocol).   This is still supported but
>>   strongly deprecated.  The main difference between the  two methods  is
>>   that  SOCK_PACKET uses the old struct sockaddr_pkt to specify an inter‐
>>   face, which doesn't provide physical layer independence.
>>
>>      struct sockaddr_pkt {
>>          unsigned short spkt_family;
>>          unsigned char  spkt_device[14];
>>          unsigned short spkt_protocol;
>>      };
>>
>>   spkt_family contains the device type, spkt_protocol is the  IEEE 802.3
>>   protocol  type  as  defined  in <sys/if_ether.h> and spkt_device is the
>>   device name as a null-terminated string, for example, eth0.
>>
>> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
>> ---
>>  linux-user/syscall.c | 30 ++++++++++++++++++++++++++++++
>>  1 file changed, 30 insertions(+)
>>
>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>> index 31b5c2c..f048437 100644
>> --- a/linux-user/syscall.c
>> +++ b/linux-user/syscall.c
>> @@ -2086,6 +2086,30 @@ static int sock_flags_fixup(int fd, int target_type)
>>      return fd;
>>  }
>>
>> +static abi_long packet_target_to_host_addr(void *host_addr,
>> +                                           abi_ulong target_addr,
>> +                                           socklen_t len)
> 
> Should the function name be ..._to_host_sockaddr ?

It was what I did in my first draft, but as I have called the type
TargetFdDataFunc and TargetFdAddrFunc, I have chosen to call the
function _addr.

If you think it is better, I can change that.

> 
> Otherwise,
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> 
> thanks
> -- PMM
>