Re: [PATCH 2/2] cifs: Correct comment about domainname length

[Chen Gang <gang.chen-bOixZGp5f+dBDgjK7y7TUQ@public.gmane.org>]

On 07/27/2013 02:12 AM, Scott Lovenberg wrote:
> On Thu, Jul 25, 2013 at 8:40 PM, Chen Gang <gang.chen-bOixZGp5f+dBDgjK7y7TUQ@public.gmane.org> wrote:
>> On 07/26/2013 02:34 AM, scott.lovenberg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:
>>> From: Scott Lovenberg <scott.lovenberg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>>
>>> CIFS_MAX_DOMAINNAME_LEN is the max length for a domain name, not a fully qualified domain name.
>>>
>>> Signed-off-by: Scott Lovenberg <scott.lovenberg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>> ---
>>>  include/uapi/linux/cifs/cifs_mount.h | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/include/uapi/linux/cifs/cifs_mount.h b/include/uapi/linux/cifs/cifs_mount.h
>>> index a58fc6e..d2408ec 100644
>>> --- a/include/uapi/linux/cifs/cifs_mount.h
>>> +++ b/include/uapi/linux/cifs/cifs_mount.h
>>> @@ -17,7 +17,7 @@
>>>  #define _CIFS_MOUNT_H
>>>
>>>  /* Max string lengths for cifs mounting options. */
>>> -#define CIFS_MAX_DOMAINNAME_LEN 256 /* max fully qualified domain name */
>>> +#define CIFS_MAX_DOMAINNAME_LEN 256 /* max domain name length */
>>>  #define CIFS_MAX_USERNAME_LEN   256 /* reasonable max for current servers */
>>>  #define CIFS_MAX_PASSWORD_LEN   512 /* Windows max seems to be 256 wide chars */
>>>  #define CIFS_MAX_SHARE_LEN      256 /* reasonable max share name length */
>>>
>>
>> For our kernel implementation:
>>
>>   for 'CIFS_MAX_DOMAINNAME_LEN', it counts 255 + '\0',
>>   for 'CIFS_MAX_USERNAME_LEN', it counts 256 (may add additional '\0'),
>>
>> And original mail said about 'CIFS_MAX_DOMAINNAME_LEN':
>>
>>   "The maximum length of ... the fully qualified domain name (FQDN) is
>>   63 octets per label and 255 bytes per FQDN. This maximum includes 254
>>   bytes for the FQDN and one byte for the ending dot."
>>
>> And excuse me, I do not know what 'CIFS_MAX_USERNAME_LEN' should be.
>>
>> Do we also need consider about it in our definition comments ?
>>
>>
>> Thanks.
>> --
>> Chen Gang
> 
> Sorry, I misunderstood; I figured that it had to be the domain name
> without the host since we were allowing a host name that's 1024
> characters long.  That documentation should probably be added to the
> cifs_mount.h as well then.
> 
> Still, how can we have a FQDN that's 256 characters long when the host
> name length can be 1024 characters long?
> 

Excuse me, I am not quite familiar about cifs, so can not provide
additional more information (I found it only by reading code).

But I feel, it really need additional discussion and check by the
related experts (related members who are familiar with cifs).

Welcome any members' suggestions and completions.

Thanks.
-- 
Chen Gang