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linux/net/dccp/diag.c
Gerrit Renker b235dc4abb dccp ccid-2: Phase out the use of boolean Ack Vector sysctl
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: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
2008-09-04 07:45:31 +02:00

72 lines
1.8 KiB
C

/*
* net/dccp/diag.c
*
* An implementation of the DCCP protocol
* Arnaldo Carvalho de Melo <acme@mandriva.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/inet_diag.h>
#include "ccid.h"
#include "dccp.h"
static void dccp_get_info(struct sock *sk, struct tcp_info *info)
{
struct dccp_sock *dp = dccp_sk(sk);
const struct inet_connection_sock *icsk = inet_csk(sk);
memset(info, 0, sizeof(*info));
info->tcpi_state = sk->sk_state;
info->tcpi_retransmits = icsk->icsk_retransmits;
info->tcpi_probes = icsk->icsk_probes_out;
info->tcpi_backoff = icsk->icsk_backoff;
info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
if (dp->dccps_hc_rx_ackvec != NULL)
info->tcpi_options |= TCPI_OPT_SACK;
ccid_hc_rx_get_info(dp->dccps_hc_rx_ccid, sk, info);
ccid_hc_tx_get_info(dp->dccps_hc_tx_ccid, sk, info);
}
static void dccp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
void *_info)
{
r->idiag_rqueue = r->idiag_wqueue = 0;
if (_info != NULL)
dccp_get_info(sk, _info);
}
static struct inet_diag_handler dccp_diag_handler = {
.idiag_hashinfo = &dccp_hashinfo,
.idiag_get_info = dccp_diag_get_info,
.idiag_type = DCCPDIAG_GETSOCK,
.idiag_info_size = sizeof(struct tcp_info),
};
static int __init dccp_diag_init(void)
{
return inet_diag_register(&dccp_diag_handler);
}
static void __exit dccp_diag_fini(void)
{
inet_diag_unregister(&dccp_diag_handler);
}
module_init(dccp_diag_init);
module_exit(dccp_diag_fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
MODULE_DESCRIPTION("DCCP inet_diag handler");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_INET_DIAG, DCCPDIAG_GETSOCK);