netdev - Re: [PATCH net-next] net: sctp: sctp_verify_init: clean up mandatory checks and add comment

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Date:	Tue, 27 Aug 2013 09:43:02 -0400
From:	Neil Horman <nhorman@...driver.com>
To:	Daniel Borkmann <dborkman@...hat.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	linux-sctp@...r.kernel.org
Subject: Re: [PATCH net-next] net: sctp: sctp_verify_init: clean up mandatory
 checks and add comment

On Tue, Aug 27, 2013 at 03:23:50PM +0200, Daniel Borkmann wrote:
> Add a comment related to RFC4960 explaning why we do not check for initial
> TSN, and while at it, remove yoda notation checks and clean up code from
> checks of mandatory conditions. That's probably just really minor, but makes
> reviewing easier.
> 
> Signed-off-by: Daniel Borkmann <dborkman@...hat.com>
> ---
>  net/sctp/sm_make_chunk.c | 26 ++++++++++++--------------
>  1 file changed, 12 insertions(+), 14 deletions(-)
> 
> diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
> index 01e9783..c6ca3c9 100644
> --- a/net/sctp/sm_make_chunk.c
> +++ b/net/sctp/sm_make_chunk.c
> @@ -2240,25 +2240,23 @@ int sctp_verify_init(struct net *net, const struct sctp_association *asoc,
>  		     struct sctp_chunk **errp)
>  {
>  	union sctp_params param;
> -	int has_cookie = 0;
> +	bool has_cookie = false;
>  	int result;
>  
> -	/* Verify stream values are non-zero. */
> -	if ((0 == peer_init->init_hdr.num_outbound_streams) ||
> -	    (0 == peer_init->init_hdr.num_inbound_streams) ||
> -	    (0 == peer_init->init_hdr.init_tag) ||
> -	    (SCTP_DEFAULT_MINWINDOW > ntohl(peer_init->init_hdr.a_rwnd))) {
> -
> +	/* Check for missing mandatory parameters. Note: Initial TSN is also
> +	 * mandatory, but not checked here since range is possible from 0 to
> +	 * 2**32-1 (4294967295), RFC4960 3.3.3.
> +	 */
nit: If we're making this easier to review, I think the above would be easier to
read if it said:
Note: Initial TSN is also mandatory, but is not checked here since the valid
range is 0..2**(32-1)

> +	if (peer_init->init_hdr.num_outbound_streams == 0 ||
> +	    peer_init->init_hdr.num_inbound_streams == 0 ||
> +	    peer_init->init_hdr.init_tag == 0 ||
> +	    ntohl(peer_init->init_hdr.a_rwnd) < SCTP_DEFAULT_MINWINDOW)
>  		return sctp_process_inv_mandatory(asoc, chunk, errp);
> -	}
>  
> -	/* Check for missing mandatory parameters.  */
>  	sctp_walk_params(param, peer_init, init_hdr.params) {
> -
> -		if (SCTP_PARAM_STATE_COOKIE == param.p->type)
> -			has_cookie = 1;
> -
> -	} /* for (loop through all parameters) */
> +		if (param.p->type == SCTP_PARAM_STATE_COOKIE)
> +			has_cookie = true;
> +	}
>  
>  	/* There is a possibility that a parameter length was bad and
>  	 * in that case we would have stoped walking the parameters.
> -- 
> 1.7.11.7
> 
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