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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2008-12-01 23:31:04 -0800
committerDavid S. Miller <davem@davemloft.net>2008-12-01 23:31:04 -0800
commit75757a7d0c54f8fdd414c74a6005d275032b0115 (patch)
tree768c07adad4a6f42723acfeada434c045f36a489 /net/dccp
parent8b7b6c75c6387527b195bb69100182288da94f84 (diff)
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@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp')
-rw-r--r--net/dccp/feat.c77
1 files changed, 75 insertions, 2 deletions
diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index d90caa7198c3..fe6d557328d6 100644
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -690,6 +690,76 @@ static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
return 0;
}
+/* 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)
+{
+ u8 c, s;
+
+ for (s = 0; s < slen; s++)
+ for (c = 0; c < clen; c++)
+ if (servlist[s] == clilist[c])
+ return servlist[s];
+ return -1;
+}
+
+/**
+ * dccp_feat_prefer - Move preferred entry to the start of array
+ * Reorder the @array_len elements in @array so that @preferred_value comes
+ * first. Returns >0 to indicate that @preferred_value does occur in @array.
+ */
+static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
+{
+ u8 i, does_occur = 0;
+
+ 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;
+ }
+ return does_occur;
+}
+
+/**
+ * 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)
+{
+ int rc;
+
+ if (!fv->sp.vec || !arr) {
+ DCCP_CRIT("NULL feature value or array");
+ return 0;
+ }
+
+ 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);
+
+ if (!reorder)
+ return rc;
+ if (rc < 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);
+}
+
+#ifdef __this_is_the_old_framework_and_will_be_removed_later_in_a_subsequent_patch
static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
u8 *rpref, u8 rlen)
{
@@ -885,6 +955,7 @@ static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
return 0;
}
+#endif /* (later) */
static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
u8 type, u8 feature)
@@ -960,12 +1031,14 @@ int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
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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