• Gerrit Renker's avatar
    dccp ccid-2: Phase out the use of boolean Ack Vector sysctl · b235dc4a
    Gerrit Renker authored
    This removes the use of the sysctl and the minisock variable for the Send Ack
    Vector feature, which is now handled fully dynamically via feature negotiation;
    i.e. when CCID2 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.
    Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
    Acked-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
    b235dc4a
diag.c 1.82 KB