Re: [lwip-users] PolarSSL and mbedTLS

[Jan Menzel]

Hi Noam!
        Did you follow the error code through mbedtls's net.c? In my code its
translated into "MBEDTLS_ERR_SSL_WANT_READ" as follows:

int mbedtls_net_recv( void *ctx, unsigned char *buf, size_t len )
[...]
    ret = (int) read( fd, buf, len );

    if( ret < 0 )
    {
        if( net_would_block( ctx ) != 0 )
            return( MBEDTLS_ERR_SSL_WANT_READ );
[...]

with

static int net_would_block( const mbedtls_net_context *ctx )
[...]
    switch( errno )
    {
#if defined EAGAIN
        case EAGAIN:
#endif
#if defined EWOULDBLOCK && EWOULDBLOCK != EAGAIN
        case EWOULDBLOCK:
#endif
            return( 1 );
    }
    return( 0 );
}

        Jan

On 15.03.2017 20:30, Noam Weissman wrote:
> Hi Simon,
> 
> I have triad debugging my code and added :
> #define LWIP_DEBUG                     LWIP_DBG_ON
> #define SOCKETS_DEBUG              LWIP_DBG_ON
> 
> Strange that with this switches on I am able to get a file of about 38K but 
> it fails at the last part, always?.
> 
> Without the debug prints it never even starts, it fails on first read. 
> 
> I have attached my debug printout if that helps.
> 
> The text is mixed with my own debug prints, sorry:
> 
> File transfer starts at line 438 with:  From WssHandleReadData: PayloadLen = 
> 38032, DataLen = 1020
> 
> The server sends chunks of 4K, my code reads 1K at a time from the ssl layer 
> hence the 1024 chunks.
> You can see that PayloadLen reduces by the DataLen chunk ...
> 
> The last part received is PayloadLen 1172 DataLen 1024 ... on line 1512
> 
> It should read one 1024 block and then 148 bytes and finish... This never 
> happens and it fails on last read
> This is consistent on every test I did ?.
> 
> If I turn off the two debug switches the file transfer never starts, actually 
> fails on first read and the lwip_recvfrom
> returns with -1 and set_errno(EWOULDBLOCK); on line 773 in sockets.c (lwip 
> ver 2.02)
> 
> 
> Any ideas ?
> 
> 
> Many thanks,
> Noam.
> 
> 
> 
> -----Original Message-----
> From: lwip-users [mailto:address@hidden On Behalf Of Simon Goldschmidt
> Sent: Friday, March 10, 2017 10:36 AM
> To: address@hidden
> Subject: Re: [lwip-users] PolarSSL and mbedTLS
> 
> Noam Weissman wrote:
>> I get a read error inside lwip_recvfrom function.
>> [..]
>> If anyone has any ideas on what more to check or test please respond.
> 
> 1: Get an idea of the error (if recvfrom returns -1, what's the corrent 
> errno?)
> 2: Get a debugger and try to find out why recvfrom returns an error. Without 
> that information, there's no way of knowing where the error is.
> 
> Simon
> 
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