[syslinux] Sending UDP packets from comboot

[Stefan Thomanek]

Yes i did, see the attached text file for the source. However, it 
doesn't work.
It does react on UDP packets, but the buffer is remains empty. Nothing 
is written to it at all.

Maybe someone is able to fix it, i'm sure its not a very big problem.
If so, reply it to the mailing list please :)


Kjetil.Mikkelborg at kongsberg.com schrieb:
> Hi great with some examples for those of us who only works with C :)
>
> Have you looked at how the same code would be for reading the responce (PXENV_UDP_READ) ??
>
> --Kjetil
>
> -----Original Message-----
> From: syslinux-bounces at zytor.com [mailto:syslinux-bounces at zytor.com] On Behalf Of Stefan Thomanek
> Sent: 30. mai 2009 22:17
> To: For discussion of Syslinux and tftp-hpa
> Subject: Re: [syslinux] Sending UDP packets from comboot
>
> H. Peter Anvin schrieb:
>   
>> Stefan Thomanek wrote:
>>   
>>     
>>> struct teststruct {
>>>    uint16_t var1;
>>>    uint8_t var2;
>>>    uint16_t var3; };
>>>
>>>     
>>>       
>> That's a 6-byte structure, unless you specify __attribute__((packed)).
>>
>>   
>>     
>>> Could anyone please take a look inside the text file and tell me where
>>> i've made mistakes?
>>>     
>>>       
>> You're overwriting your test data structure with your parameter structure:
>>
>>
>>     // Bounce testdata
>>     memcpy(__com32.cs_bounce, &test, sizeof(test));
>>
>>    [...]
>>
>>     // Bounce send struct
>>     memcpy(__com32.cs_bounce, &args, sizeof(args));
>>
>>
>> One way to do this is to put both your args and your data structure into
>> a bigger structure; another option is to calculate where in the bounce
>> buffer you can put your data.  The former is easier when you have
>> fixed-size data, the latter can be more general.
>>
>> 	-hpa
>>
>>   
>>     
> Ok, got it. Stupid me ><..
> Changed the 2nd call to
>
> 	memcpy(__com32.cs_bounce + sizeof(test), &args, sizeof(args));
>
> and the SEG/OFFS call to
>
> 	inputRegs.es = SEG(__com32.cs_bounce + sizeof(test));
> 	inputRegs.edi.w[0] = OFFS(__com32.cs_bounce + sizeof(test));
>
> It works :)
>
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