• Gerrit Renker's avatar
    dccp ccid-2: Phase out the use of boolean Ack Vector sysctl · 6fdd34d4
    Gerrit Renker authored
    This removes the use of the sysctl and the minisock variable for the Send Ack
    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)
    		/* ... */
    	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: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
    Acked-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
dccp.h 16.5 KB