Re: [PATCH 15/16] shared/gatt-helpers: Improve robustness read by type request

[Szymon Janc <szymon.janc@tieto.com>]

Hi Łukasz,

On Thursday 26 of February 2015 10:39:42 Lukasz Rymanowski wrote:
> This patch makes sure that we do get into infinite loop when doing
> read by type request.
> 
> It could happen if we got bogus read by type response
> ---
>  src/shared/gatt-helpers.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/src/shared/gatt-helpers.c b/src/shared/gatt-helpers.c
> index 8858e58..6e5cf30 100644
> --- a/src/shared/gatt-helpers.c
> +++ b/src/shared/gatt-helpers.c
> @@ -1331,10 +1331,22 @@ static void read_by_type_cb(uint8_t opcode, const void *pdu,
>  	}
>  
>  	last_handle = get_le16(pdu + length - data_length);
> +
> +	/*
> +	 * If last handle is lower from previous start handle then it is smth
> +	 * wrong. Let's stop search, otherwise we might enter infinite loop.
> +	 */
> +	if (last_handle < op->start_handle) {
> +		success = true;
> +		goto done;
> +	}

Shouldn't this be success = false ?

> +
> +	op->start_handle = last_handle + 1;
> +
>  	if (last_handle != op->end_handle) {
>  		uint8_t pdu[4 + get_uuid_len(&op->uuid)];
>  
> -		put_le16(last_handle + 1, pdu);
> +		put_le16(op->start_handle, pdu);
>  		put_le16(op->end_handle, pdu + 2);
>  		bt_uuid_to_le(&op->uuid, pdu + 4);
>  
> @@ -1376,6 +1388,7 @@ bool bt_gatt_read_by_type(struct bt_att *att, uint16_t start, uint16_t end,
>  	op->callback = callback;
>  	op->user_data = user_data;
>  	op->destroy = destroy;
> +	op->start_handle = start;
>  	op->end_handle = end;
>  	op->uuid = *uuid;
>  
> 

-- 
Best regards, 
Szymon Janc