strstr failure?

arielablumer — Mon, 18 Apr 2016 11:25:57 GMT

Hi,

I'm working on a platform w/ K66 as MCU and a GS2K device for WiFi connectiovity. Data, events and responses to commands are received in the K66 via UART. A driver parses the received buffer and forwards to RTCS/application.

It happens that the WiFi driver fails to identify events or responds. I added some debug info and it appears that strstr fails to detect strings in the received buffer.

Please find below the received buffer which was printed to log when a response was expected but driver failed to detect it.

buffer size is 106

10 13 10 58 106 49 188 67 1 16 0 1 0 0 0 0 0 0 32 70 72 70 65 69 66 69 69 67 65 67 65 67 65 67 65 67 65 67 65 67 65 67 65 67 65 67 65 67 65 65 65 0 0 32 0 1 65 84 43 87 82 83 83 73 61 63 13 13 10 45 50 50 13 10 79 75 13 10 10 13 10 65 84 43 87 82 83 83 73 61 63 13 13 10 45 50 50 13 10 79 75 13 10 10 13 10

The string I'm looking for is in the middle of the second line:

65 84 43 87 82 83 83 73 61 63 13 13 10 45 50 50 = AT+WRSSI=?

and the code is:

// parse the response at set an integer w/ the result

p_rssi_response = strstr((const char*)cmdRspBuff,(const char*)"AT+WRSSI=?");

// if we got a valid response, parse it and set a decimal result on global DB

// otherwise, rssi is set to 0, indicating the vale is invalid.

if (NULL != p_rssi_response)

{

// Expected result is AT+WRSSI=?\r\r\n-63\r\nOK\r\n

// Jump over the command and point to the response

p_rssi_response += 14;

for(i=0;i<2;i++)

{

rssi = (rssi* 10) + (p_rssi_response[i]-'0');

}

GET_CUSTOM_CXT(priv)->rssi = -rssi;

GS_DEBUG_PRINT(1, "RSSI %d p_rssi_response 0x%x\n", rssi, p_rssi_response);

Any idea what might be wrong here?

Thanks,

Ariela

Re: strstr failure?

arielablumer — Mon, 18 Apr 2016 13:20:20 GMT

Note that strstr sometimes succeeds, when it does the string I'm looking for resides at the begining of the buffer, right after carrige retrun and line feed (13 & 10).

Re: strstr failure?

MarekTrmac — Tue, 19 Apr 2016 06:12:41 GMT

Hi Ariela,

in C language, strings are terminated using zero char(0) and function strstr() does not search beyond the end of string.

Regards

Marek

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strstr failure?

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