Re: [INTERNALS-WIN] mail() sending local hostname instead of fully-qualified hostname as HELO

Kalle Sommer Nielsen wrote:
> As far as I reach the documentation, then it can be either way

I'm not sure where you saw that.  In the gethostname documentation I 
found[1], it seems to be pretty specific in the remarks section that the 
name returned will either be a simple host name or a FQDN, and that 
gethostbyname will parse it properly.

The example on the gethostbyname[2] docs *does* use the same method 
you're using (except they use isalpha rather than isdigit), but that's 
because they're taking the host name form argv rather than from gethostname.

> and I
> don't think that gethostbyname would like an IP as an argument when
> theres also the gethostbyaddr.

After a quick test, it seems that if you pass an IP address to 
gethostbyname, it just gives you that IP address back.

I did play around with passing an IP address to your fallback code, and 
found the following issues:

* You're calling gethostbyaddr incorrectly; if the code ever *did* get 
there, it would stall for a few seconds and then fail.  gethostbyaddr 
expects the first parameter to be an in_addr structure (casted to a 
char* for some stupid reason), as returned by inet_addr.  See the 
example in [3].
* If you change the code to use inet_addr, beware that it's not IPv6 
aware; you'll need to use inet_pton[4] for IPv6 code, and unfortunately 
that function is only supported by Vista and Win2k8.
* isdigit is not good enough to detect IP addresses, since an IPv6 
address can start with a colon.

> I don't if its really needed, but as a
> "just" in case to prevent future "bugs" it might be a good thing to
> also have this posibility.

Fair enough.  If the code is fixed, then it certainly wouldn't hurt.  If 
it were me, though, I just wouldn't bother; especially in light of the 
IPv6 issue.

If you still wanted to be extra-safe, it would probably be better to 
return the IP address in square-brackets, since that's a valid HELO 
value[5].

> I want to include this bug fix in the first 5.3 maintaince release
> (5.3.1), as its way to late in the 5.3 process to include this non
> critical bug fix.

I assumed as much.  I ended up changing my SMTP settings to avoid this 
bug, so I'm not in a big rush to see it fixed.

Cheers,

-Rick-

[1] http://msdn.microsoft.com/en-us/library/ms738527(VS.85).aspx
[2] http://msdn.microsoft.com/en-us/library/ms738524(VS.85).aspx
[3] http://msdn.microsoft.com/en-us/library/ms738563(VS.85).aspx
[4] http://msdn.microsoft.com/en-us/library/cc805844(VS.85).aspx
[5] http://en.wikipedia.org/wiki/Anti-spam#HELO.2FEHLO_checking