RE: [lwip-users] DNS client for lwIP raw API

[Pettinato, Jim]

Thanks Roland... I will include this change in the DNS module prior to
adding it to CVS. I haven't had much time to work on it yet as I ended
up doing some unanticipated business travel, but I'll be getting to it
soon here hopefully.


-----Original Message-----
From: address@hidden
[mailto:address@hidden On Behalf
Of Winformatik Info
Sent: Friday, July 13, 2007 11:09 AM
To: Mailing list for lwIP users
Subject: Re: [lwip-users] DNS client for lwIP raw API


Hi Jim,

I have tested the resolver code from you. It is working great... after a

little debugging. I always had the problem if the domain name to resolve

had an odd number of bytes. If this was the case, the resolver did not 
work (I use a 16-bit CPU with an alignment of 2).
To solve the problem I think we should surround the struct 
"s_dns_answer" by the two macros PACK_STRUCT_BEGIN and PACK_STRUCT_END 
(please see below). This handles a mapping of the struct "s_dns_answer" 
starting on an odd address the right way.

/* The DNS answer message structure */
PACK_STRUCT_BEGIN
typedef struct s_dns_answer {
  /* DNS answer record starts with either a domain name or a pointer
  to a name already present somewhere in the packet. */
  u16_t type;
  u16_t class;
  u16_t ttl[2];
  u16_t len;
  struct ip_addr ipaddr;
} DNS_ANSWER;
PACK_STRUCT_END

Hope this also helps others...

Roland


Pettinato, Jim schrieb:
> You're welcome... Hopefully more sweet stuff to follow. ;)
>
> -----Original Message-----
> From: address@hidden
> [mailto:address@hidden On 
> Behalf Of Taranowski, Thomas (SWCOE)
> Sent: Wednesday, June 27, 2007 2:31 PM
> To: Mailing list for lwIP users
> Subject: RE: [lwip-users] DNS client for lwIP raw API
>
>
> This is sweet.  I've been wanting some DNS functionality for awhile. 
> Thanks.
>
>   
>> -----Original Message-----
>> From: address@hidden
>> [mailto:address@hidden
>> ]
>>     
> On
>   
>> Behalf Of Pettinato, Jim
>> Sent: Tuesday, June 19, 2007 5:30 AM
>> To: Mailing list for lwIP users
>> Subject: [lwip-users] DNS client for lwIP raw API
>>
>>
>> All:
>>
>> As mentioned here before, I have ported Adam Dunkel's original uIP 
>> DNS
>>     
>
>   
>> client (resolv.c) to something that works for raw API apps. There has
>> been some interest expressed recently in this code by others, and
>>     
> since
>   
>> I don't want to keep everyone who might benefit waiting until we
>>     
> decide
>   
>> whether to integrate this into the core or maintain it as a separate
>> application, I have attached the module here.
>>
>> In the nature of the raw API, this DNS client has been implemented
>>     
> using
>   
>> the callback scheme - there is a gethostbyname() function that 
>> accepts
>>     
> a
>   
>> callback argument that is stored away if a query is required for the
>> requested host, and then is called when the DNS query completes or
>>     
> times
>   
>> out. See the header file for more details.
>>
>> The only requirements to use it (other than including the module in
>>     
> the
>   
>> build and calling gethostbyname() with an appropriate callback
>>     
> function)
>   
>> is to call resolv_init() with an appropriate DNS server IP address,
>>     
> and
>   
>> adding a call to the resolve_tmr() function approximately once a
>>     
> second
>   
>> in your timer routine.
>>
>> Let me know if you 1. can't access the attachment and 2. need this
>>     
> code
>   
>> immediately; and I'll post it as inline text or forward it to your
>> specific email address.
>>
>> - Jim
>>
>> __
>>
>>
>> James M. Pettinato, Jr.
>> Software Engineer
>> E: address@hidden | P: 814 898 5250
>>
>> FMC Technologies Measurement Solutions Inc.
>> 1602 Wagner Avenue | Erie PA | 16510 USA
>> Phone: 814 898 5000 | Fax: 814 899-3414 www.fmctechnologies.com
>>     
>
>
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