/*
* net/dccp/feat.c
*
* Feature negotiation for the DCCP protocol (RFC 4340, section 6)
*
* Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk>
* Rewrote from scratch, some bits from earlier code by
* Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
*
*
* ASSUMPTIONS
* -----------
* o Feature negotiation is coordinated with connection setup (as in TCP), wild
* changes of parameters of an established connection are not supported.
* o All currently known SP features have 1-byte quantities. If in the future
* extensions of RFCs 4340..42 define features with item lengths larger than
* one byte, a feature-specific extension of the code will be required.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
#include "ccid.h"
#include "feat.h"
/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */
unsigned long sysctl_dccp_sequence_window __read_mostly = 100;
int sysctl_dccp_rx_ccid __read_mostly = 2,
sysctl_dccp_tx_ccid __read_mostly = 2;
/*
* Feature activation handlers.
*
* These all use an u64 argument, to provide enough room for NN/SP features. At
* this stage the negotiated values have been checked to be within their range.
*/
static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
{
struct dccp_sock *dp = dccp_sk(sk);
struct ccid *new_ccid = ccid_new(ccid, sk, rx);
if (new_ccid == NULL)
return -ENOMEM;
if (rx) {
ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
dp->dccps_hc_rx_ccid = new_ccid;
} else {
ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
dp->dccps_hc_tx_ccid = new_ccid;
}
return 0;
}
static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
{
struct dccp_sock *dp = dccp_sk(sk);
if (rx) {
dp->dccps_r_seq_win = seq_win;
/* propagate changes to update SWL/SWH */
dccp_update_gsr(sk, dp->dccps_gsr);
} else {
dp->dccps_l_seq_win = seq_win;
/* propagate changes to update AWL */
dccp_update_gss(sk, dp->dccps_gss);
}
return 0;
}
static int dccp_hdlr_ack_ratio(struct sock *sk