net/dccp/feat.c - kernel/msm-4.9 - Gitiles

 /*
  *  net/dccp/feat.c
  *
  *  An implementation of the DCCP protocol
  *  Andrea Bittau <a.bittau@cs.ucl.ac.uk>
  *
  *      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/config.h>
 #include <linux/module.h>

 #include "dccp.h"
 #include "ccid.h"
 #include "feat.h"

 #define DCCP_FEAT_SP_NOAGREE (-123)

 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
 		     u8 *val, u8 len, gfp_t gfp)
 {
 	struct dccp_opt_pend *opt;

 	dccp_pr_debug("feat change type=%d feat=%d\n", type, feature);

 	/* XXX sanity check feat change request */

 	/* check if that feature is already being negotiated */
 	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 		/* ok we found a negotiation for this option already */
 		if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
 			dccp_pr_debug("Replacing old\n");
 			/* replace */
 			BUG_ON(opt->dccpop_val == NULL);
 			kfree(opt->dccpop_val);
 			opt->dccpop_val	 = val;
 			opt->dccpop_len	 = len;
 			opt->dccpop_conf = 0;
 			return 0;
 		}
 	}

 	/* negotiation for a new feature */
 	opt = kmalloc(sizeof(*opt), gfp);
 	if (opt == NULL)
 		return -ENOMEM;

 	opt->dccpop_type = type;
 	opt->dccpop_feat = feature;
 	opt->dccpop_len	 = len;
 	opt->dccpop_val	 = val;
 	opt->dccpop_conf = 0;
 	opt->dccpop_sc	 = NULL;

 	BUG_ON(opt->dccpop_val == NULL);

 	list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
 	return 0;
 }

 EXPORT_SYMBOL_GPL(dccp_feat_change);

 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
 {
 	struct dccp_sock *dp = dccp_sk(sk);
 	struct dccp_minisock *dmsk = dccp_msk(sk);
 	/* figure out if we are changing our CCID or the peer's */
 	const int rx = type == DCCPO_CHANGE_R;
 	const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
 	struct ccid *new_ccid;

 	/* Check if nothing is being changed. */
 	if (ccid_nr == new_ccid_nr)
 		return 0;

 	new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
 	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;
 		dmsk->dccpms_rx_ccid = new_ccid_nr;
 	} else {
 		ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
 		dp->dccps_hc_tx_ccid = new_ccid;
 		dmsk->dccpms_tx_ccid = new_ccid_nr;
 	}

 	return 0;
 }

 /* XXX taking only u8 vals */
 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
 {
 	dccp_pr_debug("changing [%d] feat %d to %d\n", type, feat, val);

 	switch (feat) {
 	case DCCPF_CCID:
 		return dccp_feat_update_ccid(sk, type, val);
 	default:
 		dccp_pr_debug("IMPLEMENT changing [%d] feat %d to %d\n",
 			      type, feat, val);
 		break;
 	}
 	return 0;
 }

 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
 			       u8 *rpref, u8 rlen)
 {
 	struct dccp_sock *dp = dccp_sk(sk);
 	u8 *spref, slen, *res = NULL;
 	int i, j, rc, agree = 1;

 	BUG_ON(rpref == NULL);

 	/* check if we are the black sheep */
 	if (dp->dccps_role == DCCP_ROLE_CLIENT) {
 		spref = rpref;
 		slen  = rlen;
 		rpref = opt->dccpop_val;
 		rlen  = opt->dccpop_len;
 	} else {
 		spref = opt->dccpop_val;
 		slen  = opt->dccpop_len;
 	}
 	/*
 	 * Now we have server preference list in spref and client preference in
 	 * rpref
 	 */
 	BUG_ON(spref == NULL);
 	BUG_ON(rpref == NULL);

 	/* FIXME sanity check vals */

 	/* Are values in any order?  XXX Lame "algorithm" here */
 	/* XXX assume values are 1 byte */
 	for (i = 0; i < slen; i++) {
 		for (j = 0; j < rlen; j++) {
 			if (spref[i] == rpref[j]) {
 				res = &spref[i];
 				break;
 			}
 		}
 		if (res)
 			break;
 	}

 	/* we didn't agree on anything */
 	if (res == NULL) {
 		/* confirm previous value */
 		switch (opt->dccpop_feat) {
 		case DCCPF_CCID:
 			/* XXX did i get this right? =P */
 			if (opt->dccpop_type == DCCPO_CHANGE_L)
 				res = &dccp_msk(sk)->dccpms_tx_ccid;
 			else
 				res = &dccp_msk(sk)->dccpms_rx_ccid;
 			break;

 		default:
 			WARN_ON(1); /* XXX implement res */
 			return -EFAULT;
 		}

 		dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
 		agree = 0; /* this is used for mandatory options... */
 	}

 	/* need to put result and our preference list */
 	/* XXX assume 1 byte vals */
 	rlen = 1 + opt->dccpop_len;
 	rpref = kmalloc(rlen, GFP_ATOMIC);
 	if (rpref == NULL)
 		return -ENOMEM;

 	*rpref = *res;
 	memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);

 	/* put it in the "confirm queue" */
 	if (opt->dccpop_sc == NULL) {
 		opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
 		if (opt->dccpop_sc == NULL) {
 			kfree(rpref);
 			return -ENOMEM;
 		}
 	} else {
 		/* recycle the confirm slot */
 		BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 		kfree(opt->dccpop_sc->dccpoc_val);
 		dccp_pr_debug("recycling confirm slot\n");
 	}
 	memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));

 	opt->dccpop_sc->dccpoc_val = rpref;
 	opt->dccpop_sc->dccpoc_len = rlen;

 	/* update the option on our side [we are about to send the confirm] */
 	rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
 	if (rc) {
 		kfree(opt->dccpop_sc->dccpoc_val);
 		kfree(opt->dccpop_sc);
 		opt->dccpop_sc = NULL;
 		return rc;
 	}

 	dccp_pr_debug("Will confirm %d\n", *rpref);

 	/* say we want to change to X but we just got a confirm X, suppress our
 	 * change
 	 */
 	if (!opt->dccpop_conf) {
 		if (*opt->dccpop_val == *res)
 			opt->dccpop_conf = 1;
 		dccp_pr_debug("won't ask for change of same feature\n");
 	}

 	return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
 }

 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 {
 	struct dccp_minisock *dmsk = dccp_msk(sk);
 	struct dccp_opt_pend *opt;
 	int rc = 1;
 	u8 t;

 	/*
 	 * We received a CHANGE.  We gotta match it against our own preference
 	 * list.  If we got a CHANGE_R it means it's a change for us, so we need
 	 * to compare our CHANGE_L list.
 	 */
 	if (type == DCCPO_CHANGE_L)
 		t = DCCPO_CHANGE_R;
 	else
 		t = DCCPO_CHANGE_L;

 	/* find our preference list for this feature */
 	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 		if (opt->dccpop_type != t || opt->dccpop_feat != feature)
 			continue;

 		/* find the winner from the two preference lists */
 		rc = dccp_feat_reconcile(sk, opt, val, len);
 		break;
 	}

 	/* We didn't deal with the change.  This can happen if we have no
 	 * preference list for the feature.  In fact, it just shouldn't
 	 * happen---if we understand a feature, we should have a preference list
 	 * with at least the default value.
 	 */
 	BUG_ON(rc == 1);

 	return rc;
 }

 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 {
 	struct dccp_opt_pend *opt;
 	struct dccp_minisock *dmsk = dccp_msk(sk);
 	u8 *copy;
 	int rc;

 	/* NN features must be change L */
 	if (type == DCCPO_CHANGE_R) {
 		dccp_pr_debug("received CHANGE_R %d for NN feat %d\n",
 			      type, feature);
 		return -EFAULT;
 	}

 	/* XXX sanity check opt val */

 	/* copy option so we can confirm it */
 	opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 	if (opt == NULL)
 		return -ENOMEM;

 	copy = kmalloc(len, GFP_ATOMIC);
 	if (copy == NULL) {
 		kfree(opt);
 		return -ENOMEM;
 	}
 	memcpy(copy, val, len);

 	opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
 	opt->dccpop_feat = feature;
 	opt->dccpop_val	 = copy;
 	opt->dccpop_len	 = len;

 	/* change feature */
 	rc = dccp_feat_update(sk, type, feature, *val);
 	if (rc) {
 		kfree(opt->dccpop_val);
 		kfree(opt);
 		return rc;
 	}

 	dccp_pr_debug("Confirming NN feature %d (val=%d)\n", feature, *copy);
 	list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);

 	return 0;
 }

 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
 				    u8 type, u8 feature)
 {
 	/* XXX check if other confirms for that are queued and recycle slot */
 	struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);

 	if (opt == NULL) {
 		/* XXX what do we do?  Ignoring should be fine.  It's a change
 		 * after all =P
 		 */
 		return;
 	}

 	opt->dccpop_type = type == DCCPO_CHANGE_L ? DCCPO_CONFIRM_R :
 						    DCCPO_CONFIRM_L;
 	opt->dccpop_feat = feature;
 	opt->dccpop_val	 = NULL;
 	opt->dccpop_len	 = 0;

 	/* change feature */
 	dccp_pr_debug("Empty confirm feature %d type %d\n", feature, type);
 	list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 }

 static void dccp_feat_flush_confirm(struct sock *sk)
 {
 	struct dccp_minisock *dmsk = dccp_msk(sk);
 	/* Check if there is anything to confirm in the first place */
 	int yes = !list_empty(&dmsk->dccpms_conf);

 	if (!yes) {
 		struct dccp_opt_pend *opt;

 		list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 			if (opt->dccpop_conf) {
 				yes = 1;
 				break;
 			}
 		}
 	}

 	if (!yes)
 		return;

 	/* OK there is something to confirm... */
 	/* XXX check if packet is in flight?  Send delayed ack?? */
 	if (sk->sk_state == DCCP_OPEN)
 		dccp_send_ack(sk);
 }

 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 {
 	int rc;

 	dccp_pr_debug("got feat change type=%d feat=%d\n", type, feature);

 	/* figure out if it's SP or NN feature */
 	switch (feature) {
 	/* deal with SP features */
 	case DCCPF_CCID:
 		rc = dccp_feat_sp(sk, type, feature, val, len);
 		break;

 	/* deal with NN features */
 	case DCCPF_ACK_RATIO:
 		rc = dccp_feat_nn(sk, type, feature, val, len);
 		break;

 	/* XXX implement other features */
 	default:
 		rc = -EFAULT;
 		break;
 	}

 	/* check if there were problems changing features */
 	if (rc) {
 		/* If we don't agree on SP, we sent a confirm for old value.
 		 * However we propagate rc to caller in case option was
 		 * mandatory
 		 */
 		if (rc != DCCP_FEAT_SP_NOAGREE)
 			dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
 	}

 	/* generate the confirm [if required] */
 	dccp_feat_flush_confirm(sk);

 	return rc;
 }

 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);

 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 			   u8 *val, u8 len)
 {
 	u8 t;
 	struct dccp_opt_pend *opt;
 	struct dccp_minisock *dmsk = dccp_msk(sk);
 	int rc = 1;
 	int all_confirmed = 1;

 	dccp_pr_debug("got feat confirm type=%d feat=%d\n", type, feature);

 	/* XXX sanity check type & feat */

 	/* locate our change request */
 	t = type == DCCPO_CONFIRM_L ? DCCPO_CHANGE_R : DCCPO_CHANGE_L;

 	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 		if (!opt->dccpop_conf && opt->dccpop_type == t &&
 		    opt->dccpop_feat == feature) {
 			/* we found it */
 			/* XXX do sanity check */

 			opt->dccpop_conf = 1;

 			/* We got a confirmation---change the option */
 			dccp_feat_update(sk, opt->dccpop_type,
 					 opt->dccpop_feat, *val);

 			dccp_pr_debug("feat %d type %d confirmed %d\n",
 				      feature, type, *val);
 			rc = 0;
 			break;
 		}

 		if (!opt->dccpop_conf)
 			all_confirmed = 0;
 	}

 	/* fix re-transmit timer */
 	/* XXX gotta make sure that no option negotiation occurs during
 	 * connection shutdown.  Consider that the CLOSEREQ is sent and timer is
 	 * on.  if all options are confirmed it might kill timer which should
 	 * remain alive until close is received.
 	 */
 	if (all_confirmed) {
 		dccp_pr_debug("clear feat negotiation timer %p\n", sk);
 		inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 	}

 	if (rc)
 		dccp_pr_debug("feat %d type %d never requested\n",
 			      feature, type);
 	return 0;
 }

 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);

 void dccp_feat_clean(struct dccp_minisock *dmsk)
 {
 	struct dccp_opt_pend *opt, *next;

 	list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
 				 dccpop_node) {
                 BUG_ON(opt->dccpop_val == NULL);
                 kfree(opt->dccpop_val);

 		if (opt->dccpop_sc != NULL) {
 			BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 			kfree(opt->dccpop_sc->dccpoc_val);
 			kfree(opt->dccpop_sc);
 		}

                 kfree(opt);
         }
 	INIT_LIST_HEAD(&dmsk->dccpms_pending);

 	list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 		BUG_ON(opt == NULL);
 		if (opt->dccpop_val != NULL)
 			kfree(opt->dccpop_val);
 		kfree(opt);
 	}
 	INIT_LIST_HEAD(&dmsk->dccpms_conf);
 }

 EXPORT_SYMBOL_GPL(dccp_feat_clean);

 /* this is to be called only when a listening sock creates its child.  It is
  * assumed by the function---the confirm is not duplicated, but rather it is
  * "passed on".
  */
 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
 {
 	struct dccp_minisock *olddmsk = dccp_msk(oldsk);
 	struct dccp_minisock *newdmsk = dccp_msk(newsk);
 	struct dccp_opt_pend *opt;
 	int rc = 0;

 	INIT_LIST_HEAD(&newdmsk->dccpms_pending);
 	INIT_LIST_HEAD(&newdmsk->dccpms_conf);

 	list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
 		struct dccp_opt_pend *newopt;
 		/* copy the value of the option */
 		u8 *val = kmalloc(opt->dccpop_len, GFP_ATOMIC);

 		if (val == NULL)
 			goto out_clean;
 		memcpy(val, opt->dccpop_val, opt->dccpop_len);

 		newopt = kmalloc(sizeof(*newopt), GFP_ATOMIC);
 		if (newopt == NULL) {
 			kfree(val);
 			goto out_clean;
 		}

 		/* insert the option */
 		memcpy(newopt, opt, sizeof(*newopt));
 		newopt->dccpop_val = val;
 		list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);

 		/* XXX what happens with backlogs and multiple connections at
 		 * once...
 		 */
 		/* the master socket no longer needs to worry about confirms */
 		opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */

 		/* reset state for a new socket */
 		opt->dccpop_conf = 0;
 	}

 	/* XXX not doing anything about the conf queue */

 out:
 	return rc;

 out_clean:
 	dccp_feat_clean(newdmsk);
 	rc = -ENOMEM;
 	goto out;
 }

 EXPORT_SYMBOL_GPL(dccp_feat_clone);

 static int __dccp_feat_init(struct dccp_minisock *dmsk, u8 type, u8 feat,
 			    u8 *val, u8 len)
 {
 	int rc = -ENOMEM;
 	u8 *copy = kmalloc(len, GFP_KERNEL);

 	if (copy != NULL) {
 		memcpy(copy, val, len);
 		rc = dccp_feat_change(dmsk, type, feat, copy, len, GFP_KERNEL);
 		if (rc)
 			kfree(copy);
 	}
 	return rc;
 }

 int dccp_feat_init(struct dccp_minisock *dmsk)
 {
 	int rc;

 	INIT_LIST_HEAD(&dmsk->dccpms_pending);
 	INIT_LIST_HEAD(&dmsk->dccpms_conf);

 	/* CCID L */
 	rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_CCID,
 			      &dmsk->dccpms_tx_ccid, 1);
 	if (rc)
 		goto out;

 	/* CCID R */
 	rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_R, DCCPF_CCID,
 			      &dmsk->dccpms_rx_ccid, 1);
 	if (rc)
 		goto out;

 	/* Ack ratio */
 	rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
 			      &dmsk->dccpms_ack_ratio, 1);
 out:
 	return rc;
 }

 EXPORT_SYMBOL_GPL(dccp_feat_init);
	/*
	* net/dccp/feat.c
	*
	* An implementation of the DCCP protocol
	* Andrea Bittau <a.bittau@cs.ucl.ac.uk>
	*
	* 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/config.h>
	#include <linux/module.h>

	#include "dccp.h"
	#include "ccid.h"
	#include "feat.h"

	#define DCCP_FEAT_SP_NOAGREE (-123)

	int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
	u8 *val, u8 len, gfp_t gfp)
	{
	struct dccp_opt_pend *opt;

	dccp_pr_debug("feat change type=%d feat=%d\n", type, feature);

	/* XXX sanity check feat change request */

	/* check if that feature is already being negotiated */
	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
	/* ok we found a negotiation for this option already */
	if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
	dccp_pr_debug("Replacing old\n");
	/* replace */
	BUG_ON(opt->dccpop_val == NULL);
	kfree(opt->dccpop_val);
	opt->dccpop_val = val;
	opt->dccpop_len = len;
	opt->dccpop_conf = 0;
	return 0;
	}
	}

	/* negotiation for a new feature */
	opt = kmalloc(sizeof(*opt), gfp);
	if (opt == NULL)
	return -ENOMEM;

	opt->dccpop_type = type;
	opt->dccpop_feat = feature;
	opt->dccpop_len = len;
	opt->dccpop_val = val;
	opt->dccpop_conf = 0;
	opt->dccpop_sc = NULL;

	BUG_ON(opt->dccpop_val == NULL);

	list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
	return 0;
	}

	EXPORT_SYMBOL_GPL(dccp_feat_change);

	static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
	{
	struct dccp_sock *dp = dccp_sk(sk);
	struct dccp_minisock *dmsk = dccp_msk(sk);
	/* figure out if we are changing our CCID or the peer's */
	const int rx = type == DCCPO_CHANGE_R;
	const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
	struct ccid *new_ccid;

	/* Check if nothing is being changed. */
	if (ccid_nr == new_ccid_nr)
	return 0;

	new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
	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;
	dmsk->dccpms_rx_ccid = new_ccid_nr;
	} else {
	ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
	dp->dccps_hc_tx_ccid = new_ccid;
	dmsk->dccpms_tx_ccid = new_ccid_nr;
	}

	return 0;
	}

	/* XXX taking only u8 vals */
	static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
	{
	dccp_pr_debug("changing [%d] feat %d to %d\n", type, feat, val);

	switch (feat) {
	case DCCPF_CCID:
	return dccp_feat_update_ccid(sk, type, val);
	default:
	dccp_pr_debug("IMPLEMENT changing [%d] feat %d to %d\n",
	type, feat, val);
	break;
	}
	return 0;
	}

	static int dccp_feat_reconcile(struct sock sk, struct dccp_opt_pend opt,
	u8 *rpref, u8 rlen)
	{
	struct dccp_sock *dp = dccp_sk(sk);
	u8 spref, slen, res = NULL;
	int i, j, rc, agree = 1;

	BUG_ON(rpref == NULL);

	/* check if we are the black sheep */
	if (dp->dccps_role == DCCP_ROLE_CLIENT) {
	spref = rpref;
	slen = rlen;
	rpref = opt->dccpop_val;
	rlen = opt->dccpop_len;
	} else {
	spref = opt->dccpop_val;
	slen = opt->dccpop_len;
	}
	/*
	* Now we have server preference list in spref and client preference in
	* rpref
	*/
	BUG_ON(spref == NULL);
	BUG_ON(rpref == NULL);

	/* FIXME sanity check vals */

	/* Are values in any order? XXX Lame "algorithm" here */
	/* XXX assume values are 1 byte */
	for (i = 0; i < slen; i++) {
	for (j = 0; j < rlen; j++) {
	if (spref[i] == rpref[j]) {
	res = &spref[i];
	break;
	}
	}
	if (res)
	break;
	}

	/* we didn't agree on anything */
	if (res == NULL) {
	/* confirm previous value */
	switch (opt->dccpop_feat) {
	case DCCPF_CCID:
	/* XXX did i get this right? =P */
	if (opt->dccpop_type == DCCPO_CHANGE_L)
	res = &dccp_msk(sk)->dccpms_tx_ccid;
	else
	res = &dccp_msk(sk)->dccpms_rx_ccid;
	break;

	default:
	WARN_ON(1); /* XXX implement res */
	return -EFAULT;
	}

	dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
	agree = 0; /* this is used for mandatory options... */
	}

	/* need to put result and our preference list */
	/* XXX assume 1 byte vals */
	rlen = 1 + opt->dccpop_len;
	rpref = kmalloc(rlen, GFP_ATOMIC);
	if (rpref == NULL)
	return -ENOMEM;

	rpref = res;
	memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);

	/* put it in the "confirm queue" */
	if (opt->dccpop_sc == NULL) {
	opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
	if (opt->dccpop_sc == NULL) {
	kfree(rpref);
	return -ENOMEM;
	}
	} else {
	/* recycle the confirm slot */
	BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
	kfree(opt->dccpop_sc->dccpoc_val);
	dccp_pr_debug("recycling confirm slot\n");
	}
	memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));

	opt->dccpop_sc->dccpoc_val = rpref;
	opt->dccpop_sc->dccpoc_len = rlen;

	/* update the option on our side [we are about to send the confirm] */
	rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
	if (rc) {
	kfree(opt->dccpop_sc->dccpoc_val);
	kfree(opt->dccpop_sc);
	opt->dccpop_sc = NULL;
	return rc;
	}

	dccp_pr_debug("Will confirm %d\n", *rpref);

	/* say we want to change to X but we just got a confirm X, suppress our
	* change
	*/
	if (!opt->dccpop_conf) {
	if (opt->dccpop_val == res)
	opt->dccpop_conf = 1;
	dccp_pr_debug("won't ask for change of same feature\n");
	}

	return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
	}

	static int dccp_feat_sp(struct sock sk, u8 type, u8 feature, u8 val, u8 len)
	{
	struct dccp_minisock *dmsk = dccp_msk(sk);
	struct dccp_opt_pend *opt;
	int rc = 1;
	u8 t;

	/*
	* We received a CHANGE. We gotta match it against our own preference
	* list. If we got a CHANGE_R it means it's a change for us, so we need
	* to compare our CHANGE_L list.
	*/
	if (type == DCCPO_CHANGE_L)
	t = DCCPO_CHANGE_R;
	else
	t = DCCPO_CHANGE_L;

	/* find our preference list for this feature */
	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
	if (opt->dccpop_type != t \|\| opt->dccpop_feat != feature)
	continue;

	/* find the winner from the two preference lists */
	rc = dccp_feat_reconcile(sk, opt, val, len);
	break;
	}

	/* We didn't deal with the change. This can happen if we have no
	* preference list for the feature. In fact, it just shouldn't
	* happen---if we understand a feature, we should have a preference list
	* with at least the default value.
	*/
	BUG_ON(rc == 1);

	return rc;
	}

	static int dccp_feat_nn(struct sock sk, u8 type, u8 feature, u8 val, u8 len)
	{
	struct dccp_opt_pend *opt;
	struct dccp_minisock *dmsk = dccp_msk(sk);
	u8 *copy;
	int rc;

	/* NN features must be change L */
	if (type == DCCPO_CHANGE_R) {
	dccp_pr_debug("received CHANGE_R %d for NN feat %d\n",
	type, feature);
	return -EFAULT;
	}

	/* XXX sanity check opt val */

	/* copy option so we can confirm it */
	opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
	if (opt == NULL)
	return -ENOMEM;

	copy = kmalloc(len, GFP_ATOMIC);
	if (copy == NULL) {
	kfree(opt);
	return -ENOMEM;
	}
	memcpy(copy, val, len);

	opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
	opt->dccpop_feat = feature;
	opt->dccpop_val = copy;
	opt->dccpop_len = len;

	/* change feature */
	rc = dccp_feat_update(sk, type, feature, *val);
	if (rc) {
	kfree(opt->dccpop_val);
	kfree(opt);
	return rc;
	}

	dccp_pr_debug("Confirming NN feature %d (val=%d)\n", feature, *copy);
	list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);

	return 0;
	}

	static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
	u8 type, u8 feature)
	{
	/* XXX check if other confirms for that are queued and recycle slot */
	struct dccp_opt_pend opt = kzalloc(sizeof(opt), GFP_ATOMIC);

	if (opt == NULL) {
	/* XXX what do we do? Ignoring should be fine. It's a change
	* after all =P
	*/
	return;
	}

	opt->dccpop_type = type == DCCPO_CHANGE_L ? DCCPO_CONFIRM_R :
	DCCPO_CONFIRM_L;
	opt->dccpop_feat = feature;
	opt->dccpop_val = NULL;
	opt->dccpop_len = 0;

	/* change feature */
	dccp_pr_debug("Empty confirm feature %d type %d\n", feature, type);
	list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
	}

	static void dccp_feat_flush_confirm(struct sock *sk)
	{
	struct dccp_minisock *dmsk = dccp_msk(sk);
	/* Check if there is anything to confirm in the first place */
	int yes = !list_empty(&dmsk->dccpms_conf);

	if (!yes) {
	struct dccp_opt_pend *opt;

	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
	if (opt->dccpop_conf) {
	yes = 1;
	break;
	}
	}
	}

	if (!yes)
	return;

	/* OK there is something to confirm... */
	/* XXX check if packet is in flight? Send delayed ack?? */
	if (sk->sk_state == DCCP_OPEN)
	dccp_send_ack(sk);
	}

	int dccp_feat_change_recv(struct sock sk, u8 type, u8 feature, u8 val, u8 len)
	{
	int rc;

	dccp_pr_debug("got feat change type=%d feat=%d\n", type, feature);

	/* figure out if it's SP or NN feature */
	switch (feature) {
	/* deal with SP features */
	case DCCPF_CCID:
	rc = dccp_feat_sp(sk, type, feature, val, len);
	break;

	/* deal with NN features */
	case DCCPF_ACK_RATIO:
	rc = dccp_feat_nn(sk, type, feature, val, len);
	break;

	/* XXX implement other features */
	default:
	rc = -EFAULT;
	break;
	}

	/* check if there were problems changing features */
	if (rc) {
	/* If we don't agree on SP, we sent a confirm for old value.
	* However we propagate rc to caller in case option was
	* mandatory
	*/
	if (rc != DCCP_FEAT_SP_NOAGREE)
	dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
	}

	/* generate the confirm [if required] */
	dccp_feat_flush_confirm(sk);

	return rc;
	}

	EXPORT_SYMBOL_GPL(dccp_feat_change_recv);

	int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
	u8 *val, u8 len)
	{
	u8 t;
	struct dccp_opt_pend *opt;
	struct dccp_minisock *dmsk = dccp_msk(sk);
	int rc = 1;
	int all_confirmed = 1;

	dccp_pr_debug("got feat confirm type=%d feat=%d\n", type, feature);

	/* XXX sanity check type & feat */

	/* locate our change request */
	t = type == DCCPO_CONFIRM_L ? DCCPO_CHANGE_R : DCCPO_CHANGE_L;

	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
	if (!opt->dccpop_conf && opt->dccpop_type == t &&
	opt->dccpop_feat == feature) {
	/* we found it */
	/* XXX do sanity check */

	opt->dccpop_conf = 1;

	/* We got a confirmation---change the option */
	dccp_feat_update(sk, opt->dccpop_type,
	opt->dccpop_feat, *val);

	dccp_pr_debug("feat %d type %d confirmed %d\n",
	feature, type, *val);
	rc = 0;
	break;
	}

	if (!opt->dccpop_conf)
	all_confirmed = 0;
	}

	/* fix re-transmit timer */
	/* XXX gotta make sure that no option negotiation occurs during
	* connection shutdown. Consider that the CLOSEREQ is sent and timer is
	* on. if all options are confirmed it might kill timer which should
	* remain alive until close is received.
	*/
	if (all_confirmed) {
	dccp_pr_debug("clear feat negotiation timer %p\n", sk);
	inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
	}

	if (rc)
	dccp_pr_debug("feat %d type %d never requested\n",
	feature, type);
	return 0;
	}

	EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);

	void dccp_feat_clean(struct dccp_minisock *dmsk)
	{
	struct dccp_opt_pend opt, next;

	list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
	dccpop_node) {
	BUG_ON(opt->dccpop_val == NULL);
	kfree(opt->dccpop_val);

	if (opt->dccpop_sc != NULL) {
	BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
	kfree(opt->dccpop_sc->dccpoc_val);
	kfree(opt->dccpop_sc);
	}

	kfree(opt);
	}
	INIT_LIST_HEAD(&dmsk->dccpms_pending);

	list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
	BUG_ON(opt == NULL);
	if (opt->dccpop_val != NULL)
	kfree(opt->dccpop_val);
	kfree(opt);
	}
	INIT_LIST_HEAD(&dmsk->dccpms_conf);
	}

	EXPORT_SYMBOL_GPL(dccp_feat_clean);

	/* this is to be called only when a listening sock creates its child. It is
	* assumed by the function---the confirm is not duplicated, but rather it is
	* "passed on".
	*/
	int dccp_feat_clone(struct sock oldsk, struct sock newsk)
	{
	struct dccp_minisock *olddmsk = dccp_msk(oldsk);
	struct dccp_minisock *newdmsk = dccp_msk(newsk);
	struct dccp_opt_pend *opt;
	int rc = 0;

	INIT_LIST_HEAD(&newdmsk->dccpms_pending);
	INIT_LIST_HEAD(&newdmsk->dccpms_conf);

	list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
	struct dccp_opt_pend *newopt;
	/* copy the value of the option */
	u8 *val = kmalloc(opt->dccpop_len, GFP_ATOMIC);

	if (val == NULL)
	goto out_clean;
	memcpy(val, opt->dccpop_val, opt->dccpop_len);

	newopt = kmalloc(sizeof(*newopt), GFP_ATOMIC);
	if (newopt == NULL) {
	kfree(val);
	goto out_clean;
	}

	/* insert the option */
	memcpy(newopt, opt, sizeof(*newopt));
	newopt->dccpop_val = val;
	list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);

	/* XXX what happens with backlogs and multiple connections at
	* once...
	*/
	/* the master socket no longer needs to worry about confirms */
	opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */

	/* reset state for a new socket */
	opt->dccpop_conf = 0;
	}

	/* XXX not doing anything about the conf queue */

	out:
	return rc;

	out_clean:
	dccp_feat_clean(newdmsk);
	rc = -ENOMEM;
	goto out;
	}

	EXPORT_SYMBOL_GPL(dccp_feat_clone);

	static int __dccp_feat_init(struct dccp_minisock *dmsk, u8 type, u8 feat,
	u8 *val, u8 len)
	{
	int rc = -ENOMEM;
	u8 *copy = kmalloc(len, GFP_KERNEL);

	if (copy != NULL) {
	memcpy(copy, val, len);
	rc = dccp_feat_change(dmsk, type, feat, copy, len, GFP_KERNEL);
	if (rc)
	kfree(copy);
	}
	return rc;
	}

	int dccp_feat_init(struct dccp_minisock *dmsk)
	{
	int rc;

	INIT_LIST_HEAD(&dmsk->dccpms_pending);
	INIT_LIST_HEAD(&dmsk->dccpms_conf);

	/* CCID L */
	rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_CCID,
	&dmsk->dccpms_tx_ccid, 1);
	if (rc)
	goto out;

	/* CCID R */
	rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_R, DCCPF_CCID,
	&dmsk->dccpms_rx_ccid, 1);
	if (rc)
	goto out;

	/* Ack ratio */
	rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
	&dmsk->dccpms_ack_ratio, 1);
	out:
	return rc;
	}

	EXPORT_SYMBOL_GPL(dccp_feat_init);