netdev - Re: [PATCH 17/37] dccp: Increase the scope of variable-length htonl/ntohl functions

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Date:	Thu, 28 Aug 2008 18:48:48 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Gerrit Renker <gerrit@....abdn.ac.uk>
Cc:	dccp@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 17/37] dccp: Increase the scope of variable-length
	htonl/ntohl functions

Em Thu, Aug 28, 2008 at 07:44:52PM +0200, Gerrit Renker escreveu:
> This extends the scope of two available functions, encode|decode_value_var,
> to work up to 6 (8) bytes, to match maximum requirements in the RFC.
> 
> These functions are going to be used both by general option processing and
> feature negotiation code, hence declarations have been put into feat.h.
> 
> Signed-off-by: Gerrit Renker <gerrit@....abdn.ac.uk>
> Acked-by: Ian McDonald <ian.mcdonald@...di.co.nz>


Acked-by: Arnaldo Carvalho de Melo <acme@...hat.com>

> ---
>  net/dccp/feat.h    |   14 ++++++++++++++
>  net/dccp/options.c |   21 ++++++++++++++-------
>  2 files changed, 28 insertions(+), 7 deletions(-)
> 
> --- a/net/dccp/feat.h
> +++ b/net/dccp/feat.h
> @@ -122,4 +122,18 @@ extern int  dccp_feat_clone(struct sock *oldsk, struct sock *newsk);
>  extern int  dccp_feat_clone_list(struct list_head const *, struct list_head *);
>  extern int  dccp_feat_init(struct sock *sk);
>  
> +/*
> + * Encoding variable-length options and their maximum length.
> + *
> + * This affects NN options (SP options are all u8) and other variable-length
> + * options (see table 3 in RFC 4340). The limit is currently given the Sequence
> + * Window NN value (sec. 7.5.2) and the NDP count (sec. 7.7) option, all other
> + * options consume less than 6 bytes (timestamps are 4 bytes).
> + * When updating this constant (e.g. due to new internet drafts / RFCs), make
> + * sure that you also update all code which refers to it.
> + */
> +#define DCCP_OPTVAL_MAXLEN	6
> +
> +extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
> +extern u64  dccp_decode_value_var(const u8 *bf, const u8 len);
>  #endif /* _DCCP_FEAT_H */
> --- a/net/dccp/options.c
> +++ b/net/dccp/options.c
> @@ -29,16 +29,20 @@ int sysctl_dccp_feat_tx_ccid	      = DCCPF_INITIAL_CCID;
>  int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
>  int sysctl_dccp_feat_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
>  
> -static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
> +u64 dccp_decode_value_var(const u8 *bf, const u8 len)
>  {
> -	u32 value = 0;
> +	u64 value = 0;
>  
> +	if (len >= DCCP_OPTVAL_MAXLEN)
> +		value += ((u64)*bf++) << 40;
> +	if (len > 4)
> +		value += ((u64)*bf++) << 32;
>  	if (len > 3)
> -		value += *bf++ << 24;
> +		value += ((u64)*bf++) << 24;
>  	if (len > 2)
> -		value += *bf++ << 16;
> +		value += ((u64)*bf++) << 16;
>  	if (len > 1)
> -		value += *bf++ << 8;
> +		value += ((u64)*bf++) << 8;
>  	if (len > 0)
>  		value += *bf;
>  
> @@ -298,9 +302,12 @@ out_invalid_option:
>  
>  EXPORT_SYMBOL_GPL(dccp_parse_options);
>  
> -static void dccp_encode_value_var(const u32 value, unsigned char *to,
> -				  const unsigned int len)
> +void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
>  {
> +	if (len >= DCCP_OPTVAL_MAXLEN)
> +		*to++ = (value & 0xFF0000000000ull) >> 40;
> +	if (len > 4)
> +		*to++ = (value & 0xFF00000000ull) >> 32;
>  	if (len > 3)
>  		*to++ = (value & 0xFF000000) >> 24;
>  	if (len > 2)
> -- 
> 1.6.0.rc2
> 
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