WG: [lwip-users] DNS for socket API

[Mathias Zenger]

Thanks for your hint. I dug even deeper but still wasn't successful. At the
end I was able to break in

do_dns_found(const char *name, struct ip_addr *ipaddr, void *arg)

This method returns ERR_VAL (-8) which says "timeout or memory error" or
"illegal value" or "dns server response was invalid" respectively (depending
on different method comments).

I guess that my name argument is OK. At least my debugger resolves the name
pointer to "ntpbmt01.dyndns.org" which is the desired server. The second
argument (addr) gets defined in netconn_gethostbyname(). I am only passing
the name pointer to gethostbyname(). Could there anyway be a problem with
the memory (e.g. a missing memory allocation / lwIP configuration setting)?
Still there is no DNS packet output which I would expect to see after the
call of dns_enqueue()...



-----Ursprüngliche Nachricht-----
Von: Pettinato, Jim [mailto:address@hidden
Gesendet: Freitag, 4. September 2009 17:27
An: address@hidden; Mailing list for lwIP users
Betreff: RE: [lwip-users] DNS for socket API



-8 (ERR_ARG) would appear to indicate that the netconn_gethostbyname()
function is being passed either a NULL pointer for the name to look up, or a
NULL pointer for the destination to write the resolved IP address. Check
your arguments to the call; my guess would be perhaps you are a level of
indirection off on your addr argument (i.e. passing the value instead of the
address of your ip_addr variable).


-----Original Message-----
From: address@hidden
[mailto:address@hidden On Behalf Of
Mathias Zenger
Sent: Friday, September 04, 2009 10:40 AM
To: Mailing list for lwIP users
Subject: AW: [lwip-users] DNS for socket API

Hi,

I am working on my 'problem' again.

My call of gethostbyname() after a few seconds always returns NULL. I set a
breakpoint within this function and saw that

err = netconn_gethostbyname(name, &addr);

returns the error code -8. Unfortunately I still don't know what I am doing
wrong. DHCP works fine and gives the correct DNS server address. LWIP_DNS is
set to 1. There is no packet output from my device to the DNS server at all
(no packet captured with Wireshark). Is there a special need to 'somehow
handle' the DNS server address?

To solve my previous problems I replaced the netdb.c/h files in my stack.
Afterwards the compiler errors/warnings disappeared. Was it a bad idea to
just replace the two 1.3.0 files by the 1.3.1 version?

Any other ideas? Thanks.
Regards,
Mathias


-----Ursprüngliche Nachricht-----
Von: address@hidden
[mailto:address@hidden Auftrag von
address@hidden
Gesendet: Dienstag, 11. August 2009 16:41
An: Mailing list for lwIP users
Betreff: Re: [lwip-users] DNS for socket API


Simon Goldschmidt wrote:
>> In netdb.c I get some warnings for implicit declarations of strlen(),
>> memcpy() and memset(). This probably could indicate a missing
>> string.h include.
>>
> That could well be as I think the example ports include string.h in
> their
port-defined cc.h file. Just try to add the missing include in netdb.c until
we added it to CVS.
>
I've just added #include <string.h> to netdb.c in CVS.
>> The error in netdb.c says 'conflicting types for lwip_gethostbyname_r'.
In
>> netdb.h I get the error messages 'previous declaration of
>> lwip_gethostbyname_r was here' and 'expected declaration specifiers
>> or '...'
>> before size_t'
>>
>
> That would mean another standard include is missing in netdb.h. I'll
> check
that.
>
#include <stddef.h> was added to netdb.h 2 weeks ago.

Simon


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