[DCCP]: Preference list reconciliation
This provides two functions to
* reconcile preference lists (with appropriate return codes) and
* reorder the preference list if successful reconciliation changed the
preferred value.
The patch also removes the old code for processing SP/NN Change options, since
new code to process these is mostly there already; related references have been
commented out.
The code for processing Change options follows in the next patch.
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
---
net/dccp/feat.c | 230 ++++++++++++--------------------------------------------
1 file changed, 50 insertions(+), 180 deletions(-)
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -655,200 +655,68 @@ static int dccp_feat_update(struct sock
return 0;
}
-static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
- u8 *rpref, u8 rlen)
+/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
+static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
{
- 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 */
- 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:
- DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
- /* XXX implement res */
- return -EFAULT;
- }
+ u8 c, s;
- 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 */
- 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 */
+ for (s = 0; s < slen; s++)
+ for (c = 0; c < clen; c++)
+ if (servlist[s] == clilist[c])
+ return servlist[s];
+ return -1;
}
-static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
+/* Reorder array so that the preferred value comes first. Returns > 0 on success. */
+static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_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;
+ u8 i, does_occur = 0;
- /* 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;
+ if (array != NULL) {
+ for (i = 0; i < array_len; i++)
+ if (array[i] == preferred_value) {
+ array[i] = array[0];
+ does_occur++;
+ }
+ if (does_occur)
+ array[0] = preferred_value;
}
-
- /* 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;
+ return does_occur;
}
-static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
+/**
+ * dccp_feat_reconcile - Reconcile SP preference lists
+ * @fval: SP list to reconcile into
+ * @arr: received SP preference list
+ * @len: length of @arr in bytes
+ * @is_server: whether this side is the server (and @fv is the server's list)
+ * @reorder: whether to reorder the list in @fv after reconciling with @arr
+ * When successful, > 0 is returned and the reconciled list is in @fval.
+ * A value of 0 means that negotiation failed (no shared entry).
+ */
+static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
+ bool is_server, bool reorder)
{
- struct dccp_opt_pend *opt;
- struct dccp_minisock *dmsk = dccp_msk(sk);
- u8 *copy;
int rc;
- /* NN features must be Change L (sec. 6.3.2) */
- if (type != DCCPO_CHANGE_L) {
- dccp_pr_debug("received %s for NN feature %d\n",
- dccp_feat_typename(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 = kmemdup(val, len, GFP_ATOMIC);
- if (copy == NULL) {
- kfree(opt);
- return -ENOMEM;
- }
+ BUG_TRAP(fv->sp.vec != NULL && arr != NULL);
+ if (!fv->sp.vec || !arr)
+ return 0;
- opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
- opt->dccpop_feat = feature;
- opt->dccpop_val = copy;
- opt->dccpop_len = len;
+ if (is_server)
+ rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
+ else
+ rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
- /* change feature */
- rc = dccp_feat_update(sk, type, feature, *val);
- if (rc) {
- kfree(opt->dccpop_val);
- kfree(opt);
+ if (!reorder)
return rc;
- }
-
- dccp_feat_debug(type, feature, *copy);
-
- list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
+ if (rc < 0)
+ return 0;
- return 0;
+ /*
+ * Reorder list: used for activating features and in dccp_insert_fn_opt.
+ */
+ return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
}
static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
@@ -925,12 +793,14 @@ int dccp_feat_change_recv(struct sock *s
switch (feature) {
/* deal with SP features */
case DCCPF_CCID:
- rc = dccp_feat_sp(sk, type, feature, val, len);
+ /* XXX Obsoleted by next patch
+ 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);
+ /* XXX Obsoleted by next patch
+ rc = dccp_feat_nn(sk, type, feature, val, len); */
break;
/* XXX implement other features */
-
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