[DCCP]: Initial feature negotiation implementation

Still needs more work, but boots and doesn't crashes, even
does some negotiation!

18:38:52.174934  127.0.0.1.43458 > 127.0.0.1.5001: request <change_l ack_ratio 2, change_r ccid 2, change_l ccid 2>
18:38:52.218526  127.0.0.1.5001 > 127.0.0.1.43458: response <nop, nop, change_l ack_ratio 2, confirm_r ccid 2 2, confirm_l ccid 2 2, confirm_r ack_ratio 2>
18:38:52.185398  127.0.0.1.43458 > 127.0.0.1.5001: <nop, confirm_r ack_ratio 2, ack_vector0 0x00, elapsed_time 212>

:-)

Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 554 insertions, 0 deletions

diff --git a/net/dccp/feat.c b/net/dccp/feat.c
new file mode 100644
index 000000000000..99d7b7f9efa9
--- /dev/null
+++ b/net/dccp/feat.c
@@ -0,0 +1,554 @@
+/*
+ *  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 "feat.h"
+
+#define DCCP_FEAT_SP_NOAGREE (-123)
+
+int dccp_feat_change(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len,
+                     gfp_t gfp)
+{
+        struct dccp_sock *dp = dccp_sk(sk);
+        struct dccp_opt_pend *opt;
+
+        dccp_pr_debug("feat change type=%d feat=%d\n", type, feature);
+
+        /* check if that feature is already being negotiated */
+        list_for_each_entry(opt, &dp->dccps_options.dccpo_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, &dp->dccps_options.dccpo_pending);
+        return 0;
+}
+
+EXPORT_SYMBOL_GPL(dccp_feat_change);
+
+/* XXX taking only u8 vals */
+static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
+{
+        /* FIXME implement */
+        dccp_pr_debug("changing [%d] feat %d to %d\n", type, feat, val);
+        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 = &dp->dccps_options.dccpo_tx_ccid;
+                        else
+                                res = &dp->dccps_options.dccpo_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 = 0;
+                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_sock *dp = dccp_sk(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, &dp->dccps_options.dccpo_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_sock *dp = dccp_sk(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, &dp->dccps_options.dccpo_conf);
+
+        return 0;
+}
+
+static void dccp_feat_empty_confirm(struct sock *sk, u8 type, u8 feature)
+{
+        struct dccp_sock *dp = dccp_sk(sk);
+        /* 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  = 0;
+        opt->dccpop_len  = 0;
+
+        /* change feature */
+        dccp_pr_debug("Empty confirm feature %d type %d\n", feature, type);
+        list_add_tail(&opt->dccpop_node, &dp->dccps_options.dccpo_conf);
+}
+
+static void dccp_feat_flush_confirm(struct sock *sk)
+{
+        struct dccp_sock *dp = dccp_sk(sk);
+        /* Check if there is anything to confirm in the first place */
+        int yes = !list_empty(&dp->dccps_options.dccpo_conf);
+
+        if (!yes) {
+                struct dccp_opt_pend *opt;
+
+                list_for_each_entry(opt, &dp->dccps_options.dccpo_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(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_sock *dp = dccp_sk(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, &dp->dccps_options.dccpo_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 sock *sk)
+{
+        struct dccp_sock *dp = dccp_sk(sk);
+        struct dccp_opt_pend *opt, *next;
+
+        list_for_each_entry_safe(opt, next, &dp->dccps_options.dccpo_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(&dp->dccps_options.dccpo_pending);
+
+        list_for_each_entry_safe(opt, next, &dp->dccps_options.dccpo_conf,
+                                 dccpop_node) {
+                BUG_ON(opt == NULL);
+                if (opt->dccpop_val != NULL)
+                        kfree(opt->dccpop_val);
+                kfree(opt);
+        }
+        INIT_LIST_HEAD(&dp->dccps_options.dccpo_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_sock *olddp = dccp_sk(oldsk);
+        struct dccp_sock *newdp = dccp_sk(newsk);
+        struct dccp_opt_pend *opt;
+        int rc = 0;
+
+        INIT_LIST_HEAD(&newdp->dccps_options.dccpo_pending);
+        INIT_LIST_HEAD(&newdp->dccps_options.dccpo_conf);
+
+        list_for_each_entry(opt, &olddp->dccps_options.dccpo_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,
+                              &newdp->dccps_options.dccpo_pending);
+
+                /* XXX what happens with backlogs and multiple connections at
+                 * once...
+                 */
+                /* the master socket no longer needs to worry about confirms */
+                opt->dccpop_sc = 0; /* 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(newsk);
+        rc = -ENOMEM;
+        goto out;
+}
+
+EXPORT_SYMBOL_GPL(dccp_feat_clone);
+
+static int __dccp_feat_init(struct sock *sk, 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(sk, type, feat, copy, len, GFP_KERNEL);
+                if (rc)
+                        kfree(copy);
+        }
+        return rc;
+}
+
+int dccp_feat_init(struct sock *sk)
+{
+        struct dccp_sock *dp = dccp_sk(sk);
+        int rc;
+
+        INIT_LIST_HEAD(&dp->dccps_options.dccpo_pending);
+        INIT_LIST_HEAD(&dp->dccps_options.dccpo_conf);
+
+        /* CCID L */
+        rc = __dccp_feat_init(sk, DCCPO_CHANGE_L, DCCPF_CCID,
+                              &dp->dccps_options.dccpo_tx_ccid, 1);
+        if (rc)
+                goto out;
+
+        /* CCID R */
+        rc = __dccp_feat_init(sk, DCCPO_CHANGE_R, DCCPF_CCID,
+                              &dp->dccps_options.dccpo_rx_ccid, 1);
+        if (rc)
+                goto out;
+
+        /* Ack ratio */
+        rc = __dccp_feat_init(sk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
+                              &dp->dccps_options.dccpo_ack_ratio, 1);
+out:
+        return rc;
+}
+
+EXPORT_SYMBOL_GPL(dccp_feat_init);