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RE: [lwip-users] DNS question
From: |
Chuck Kuecker |
Subject: |
RE: [lwip-users] DNS question |
Date: |
Fri, 14 Aug 2009 13:06:08 -0500 |
Perfect. That fixes it!
Thanks!
Chuck
-----Original Message-----
From: address@hidden
[mailto:address@hidden On
Behalf Of Pettinato, Jim
Sent: Friday, August 14, 2009 12:51 PM
To: Mailing list for lwIP users
Subject: RE: [lwip-users] DNS question
Chuck,
The IP address pointer will be NULL on an error.
See the wiki for more details... http://lwip.wikia.com/wiki/LwIP_wiki
A sample DNS callback:
// callback for DNS queries for SMTP server name
void smtp_serverFound(char *name, struct ip_addr *ipaddr, void
*callback_arg)
{
if ((ipaddr) && (ipaddr->addr))
{
smtp.serverIP.addr = ipaddr->addr;
smtp.state = SMTP_NAME_RESOLVED;
if (smtp_connect() == ERR_OK)
return;
smtp.lastError = SMTP_CONNECT_FAILED;
}
else
smtp.lastError = SMTP_UNKNOWN_HOST;
smtp.state = SMTP_IDLE;
}
Hope this helps!
- 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
-----Original Message-----
From: address@hidden
[mailto:address@hidden On Behalf
Of Chuck Kuecker
Sent: Friday, August 14, 2009 12:09 PM
To: Mailing list for lwIP users
Subject: RE: [lwip-users] DNS question
Does it help to mention that I am using the TI/Luminary Stellaris
library version of LWIP? They don't mention an LWIP revision, just an
overall library revision of 2942.
Chuck
-----Original Message-----
From: address@hidden
[mailto:address@hidden On
Behalf Of Kieran Mansley
Sent: Friday, August 14, 2009 10:41 AM
To: Mailing list for lwIP users
Subject: RE: [lwip-users] DNS question
On Fri, 2009-08-14 at 10:20 -0500, Chuck Kuecker wrote:
> Hi, Kieran,
>
> My impression was that dns_gethostbyname() would return ERR_OK if it
did
> not encounter anything fatal, but would actually set up the DNS query
> for transmission in the background, so that dns_gethostbyname()
returns
> immediately, and would only have good information if the resolution
was
> already in the DNS tables.
Take a look at the source. If it already knows the answer it fills it
in and returns ERR_OK. Otherwise it will work asynchronously and call
the specified callback when it knows the answer (or error, or timeout).
> Since I am booting the processor every time I need to resolve DNS, I
> can't expect a previously resolved IP to be in memory.
So then it will always work asynchronously.
> The callback always gets called sometime after dns_gethostbyname() is
> called. I use the argument parameter to let me know which URL I have
> been working with. In case of a DNS failure, I need to abort further
> processing.
So if you get an error in your callback set some global state that you
check before doing any processing, and abort the further processing if
that state is set.
Kieran
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- [lwip-users] DNS question, Chuck Kuecker, 2009/08/14
- Re: [lwip-users] DNS question, Kieran Mansley, 2009/08/14
- RE: [lwip-users] DNS question, Chuck Kuecker, 2009/08/14
- RE: [lwip-users] DNS question, Kieran Mansley, 2009/08/14
- RE: [lwip-users] DNS question, Chuck Kuecker, 2009/08/14
- RE: [lwip-users] DNS question, Chuck Kuecker, 2009/08/14
- RE: [lwip-users] DNS question, Pettinato, Jim, 2009/08/14
- RE: [lwip-users] DNS question,
Chuck Kuecker <=