RE: [lwip-users] DNS for socket API

[Pettinato, Jim]

Sorry for assuming the simplest source of your problem - I pretty much strictly 
use the raw API, so am less familiar with the socket / netconn API.

Can you verify that the DHCP-returned DNS server IP is being stored properly? 
It should be stuffed into dns.c's static array variable dns_servers[0].

There are at minimum the following memory requirements for DNS to work... You 
need an available UDP pcb, one open entry in the DNS table (i.e. DNS_TABLE_SIZE 
large enough for all resolved names) and some free pbufs in the pool to send 
the packet.

Is dns_send() getting called or is it not getting that far?

Do you have stats enabled? Any allocation errors should show up in the 
associated memory structure's stats.
 

-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Mathias Zenger
Sent: Tuesday, September 08, 2009 10:33 AM
To: address@hidden
Subject: WG: [lwip-users] DNS for socket API

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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