From: Gerrit Renker

Date: Sat,  6 Dec 2008 17:40:57 +0100
> This removes the use of the sysctl and the minisock variable for the Send Ack

quoted text
> Vector feature, as it now is handled fully dynamically via feature negotiation

> (i.e. when CCID-2 is enabled, Ack Vectors are automatically enabled as per

>  RFC 4341, 4.).

>

> Using a sysctl in parallel to this implementation would open the door to

> crashes, since much of the code relies on tests of the boolean minisock /

> sysctl variable. Thus, this patch replaces all tests of type

>

> 	if (dccp_msk(sk)->dccpms_send_ack_vector)

> 		/* ... */

> with

> 	if (dp->dccps_hc_rx_ackvec != NULL)

> 		/* ... */

>

> The dccps_hc_rx_ackvec is allocated by the dccp_hdlr_ackvec() when feature

> negotiation concluded that Ack Vectors are to be used on the half-connection.

> Otherwise, it is NULL (due to dccp_init_sock/dccp_create_openreq_child),

> so that the test is a valid one.

>

> The activation handler for Ack Vectors is called as soon as the feature

> negotiation has concluded at the

>  * server when the Ack marking the transition RESPOND => OPEN arrives;

>  * client after it has sent its ACK, marking the transition REQUEST => PARTOPEN.

>

> Adding the sequence number of the Response packet to the Ack Vector has been

> removed, since

>  (a) connection establishment implies that the Response has been received;

>  (b) the CCIDs only look at packets received in the (PART)OPEN state, i.e.

>      this entry will always be ignored;

>  (c) it can not be used for anything useful - to detect loss for instance, only

>      packets received after the loss can serve as pseudo-dupacks.

>

> There was a FIXME to change the error code when dccp_ackvec_add() fails.

> I removed this after finding out that:

>  * the check whether ackno < ISN is already made earlier,

>  * this Response is likely the 1st packet with an Ackno that the client gets,

>  * so when dccp_ackvec_add() fails, the reason is likely not a packet error.

>

>

> Signed-off-by: Gerrit Renker

> Acked-by: Ian McDonald 

Also applied, thanks Gerrit.

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