On 07/30/2013 08:09 AM, Chen Gang wrote: > On 07/30/2013 05:10 AM, Scott Lovenberg wrote: >> On Mon, Jul 29, 2013 at 4:17 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: >>>>>> 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. >>>> >>>> Come on guys, enough already. As per here: >>>> https://en.wikipedia.org/wiki/Domain_Name_System >>>> >>>> and a comment above the max len 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. >>>> >>> >>> Ok, I think I knew that at one point and paged it out. It does make one >>> wonder why NI_MAXHOST is so big though -- is that for some >>> internationalization scheme? >>> >>> -- >>> Jeff Layton <jlayton@xxxxxxxxxx> >> >> I guess it works if you're storing as UTF-32 or wchar_t at 4 bytes per >> character. 256 characters * 4 bytes/char + 1 byte for NULL. Microsoft >> seems to use the same value for NI_MAXHOST ref: >> http://msdn.microsoft.com/en-us/library/windows/desktop/ms738532(v=vs.85).aspx >> . >> > > As far as I know, the kernel implementation wants to use 255 + 1 as > character count, not bytes count for FQDN (256 bytes for 8-bit, 512 > bytes for 16-bit, ...), it can be translated into uni-code or other > format within 255 + 1 character count. > > May it be useful for our discussion ? > > (BTW: if kernel really wants to do, I also suggest to check the kernel > implementation for it whether correct or not). > > > Thanks. > OH, sorry, what I said above is incorrect. The kernel implementation use 255 + 1 as bytes, it can be translated into uni-code within 255 + 1 character count. For NI_MAXHOST, I think we do not mind it: WIKI is more common than Microsoft. and Microsoft also says: "To simplify determining buffer requirements ..." (I guess, the "simplify determining" is "sizeof(UTF-32) * 256 + '\0'"). :-) Thanks. -- Chen Gang -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
