Strange resolver behavior

[Xin LI]

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Hajimu UMEMOTO wrote:
> Hi,
> 
>>>>>> On Tue, 12 Feb 2008 17:31:57 -0800
>>>>>> Xin LI <delphij at delphij.net> said:
> 
> delphij> [delphij at charlie] ~> host ps_other.a.shifen.com
> delphij> ps_other.a.shifen.com has address 202.108.22.46
> delphij> Host ps_other.a.shifen.com not found: 3(NXDOMAIN)
> 
> `_' is not allowed in hostname.  Our resolver (BIND's resolver)
> rejects it.
> If you don't want this behavior, you can try the following patch, but
> I don't recommend:
> 
> Index: lib/libc/resolv/res_comp.c
> diff -u -p lib/libc/resolv/res_comp.c.orig lib/libc/resolv/res_comp.c
> --- lib/libc/resolv/res_comp.c.orig	2006-07-17 19:09:58.000000000 +0900
> +++ lib/libc/resolv/res_comp.c	2008-02-13 13:14:35.000000000 +0900
> @@ -151,7 +151,7 @@ dn_skipname(const u_char *ptr, const u_c
>  #define digitchar(c) ((c) >= 0x30 && (c) <= 0x39)
>  
>  #define borderchar(c) (alphachar(c) || digitchar(c))
> -#define middlechar(c) (borderchar(c) || hyphenchar(c))
> +#define middlechar(c) (borderchar(c) || hyphenchar(c) || ((c) == 0x5f))
>  #define	domainchar(c) ((c) > 0x20 && (c) < 0x7f)
>  
>  int

I see.

The problem for this is that others (Windows, CentOS) does not enforce
this.  Except the RFC violation, is there any other risk having this
compatibility?

Cheers,
- --
Xin LI <delphij at delphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!
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