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From:   "=?utf-8?Q?Micha=C5=82?= Lowas-Rzechonek" 
        <michal.lowas-rzechonek@silvair.com>
Date:   Thu, 9 Jan 2020 22:00:06 +0100
To:     Inga Stotland <inga.stotland@intel.com>
Cc:     linux-bluetooth@vger.kernel.org, brian.gix@intel.com
Subject: Re: [PATCH BlueZ] mesh: Correctly generate NetKey list
Message-ID: <20200109210006.e3qv6uxnr2w3isc5@kynes>
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        linux-bluetooth@vger.kernel.org, brian.gix@intel.com
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Hi Inga,

On 01/09, Inga Stotland wrote:
> When responding with NetKey List Status, packed NetKey indices into
> 3 octets per pair. If number of NetKeys is odd, append the last key
> index as a 2-octet value.
> ---
>  mesh/net.c | 36 ++++++++++++++++++++++++++++--------
>  1 file changed, 28 insertions(+), 8 deletions(-)
> 
> diff --git a/mesh/net.c b/mesh/net.c
> index 0a4d2e72c..90ebdf496 100644
> --- a/mesh/net.c
> +++ b/mesh/net.c
> @@ -1065,26 +1065,46 @@ bool mesh_net_get_key(struct mesh_net *net, bool new_key, uint16_t idx,
>  bool mesh_net_key_list_get(struct mesh_net *net, uint8_t *buf, uint16_t *size)
>  {
>  	const struct l_queue_entry *entry;
> -	uint16_t n, buf_size;
> +	uint16_t num_keys, req_size, buf_size;
> +	struct mesh_subnet *subnet;
>  
>  	if (!net || !buf || !size)
>  		return false;
>  
>  	buf_size = *size;
> -	if (buf_size < l_queue_length(net->subnets) * 2)
> +
> +	num_keys = l_queue_length(net->subnets);
> +	req_size = (num_keys >> 1) * 3 + (num_keys % 2) * 2;

Please don't use bit shifts for division.

Also, I think it's clearer to write this as:
    req_size = num_keys * 3 - num_keys % 2

> +
> +	if (buf_size < req_size)
>  		return false;
>  
> -	n = 0;
> -	entry = l_queue_get_entries(net->subnets);
> +	*size = req_size;
> +
> +	/* Pack NetKey indices in 3 octets */
> +	for (entry = l_queue_get_entries(net->subnets); num_keys > 1;) {
> +		uint32_t idx_pair;
>  
> -	for (; entry; entry = entry->next) {
> -		struct mesh_subnet *subnet = entry->data;
> +		subnet = entry->data;
> +		idx_pair = subnet->idx;
> +		idx_pair <<= 12;
> +
> +		subnet = entry->next->data;
> +		idx_pair += subnet->idx;
> +
> +		l_put_le32(idx_pair, buf);
> +		buf += 3;
> +
> +		num_keys -= 2;
> +		entry = entry->next->next;
> +	}
>  
> +	/* If odd number of NetKeys, fill in the end of the buffer */
> +	if (num_keys % 2) {
> +		subnet = entry->data;
>  		l_put_le16(subnet->idx, buf);
> -		n += 2;
>  	}
>  
> -	*size = n;
>  	return true;
>  }

Tested-by: Michał Lowas-Rzechonek <michal.lowas-rzechonek@silvair.com>

-- 
Michał Lowas-Rzechonek <michal.lowas-rzechonek@silvair.com>
Silvair http://silvair.com
Jasnogórska 44, 31-358 Krakow, POLAND