Re: [lwip-users] mbedtls

[Trampas Stern]

It appears that  ALTCP_MBEDTLS_ENTROPY_PTR  is a memory location not a pointer to function. 

I just went in and hacked the entropy_poll.c and created a new function: 

int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len,
                           size_t *olen )
{
size_t i=0;
while(i<len)
{
uint32_t x;
uint8_t *ptr;
x=get_random();
ptr=&x;
uint32_t j=0;
while (i<len && j<4)
{
output[i]=ptr[j];
i++;
j++;
}
}
*olen = i;

   return( 0 );
}

This got me passed that bug, however when running the https server I am unable to connect with Chrome.  I am trying to determine the root cause. 

Trampas

On Mon, Feb 17, 2020 at 3:39 PM address@hidden <address@hidden> wrote:

Am 17.02.2020 um 18:09 schrieb Trampas Stern:
> Does anyone know how on an embedded platform to setup the entropy using
> mbedtls?

I did that, but it's been a while, and I don't remember from the top of
my head.

I think you *can* use a string entropy source and implement that
correctly or you can enable some kind of debug option that says
somethink like "this is for testing only; using no entropy is ok"...

>
> Specifically I am trying to get https running with lwip and getting an
> assertion failure:
>
> Assertion "httpd_init: altcp_tls_new failed" failed at line 2872 in
> ../src/libraries/lwip/src/apps/http/httpd.c
>
> Which I think is because of lack of entropy functions.  
>
> I did try defining ALTCP_MBEDTLS_ENTROPY_PTR
> and  ALTCP_MBEDTLS_ENTROPY_LEN but that seems to cause hard faults, when
> I assign it to a function pointer that generates a random number.

That seems strange.

Regards,
Simon

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