dccp: Mechanism to resolve CCID dependencies
This adds a hook to resolve features whose value depends on the choice of
CCID. It is done at the server since it can only be done after the CCID
values have been negotiated; i.e. the client will add its CCID preference
list on the Change options sent in the Request, which will be reconciled
with the local preference list of the server.
The concept is documented on
http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/feature_negotiation/\
implementation_notes.html#ccid_dependencies
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index ed9f50b..6852960 100644
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -601,6 +601,31 @@
return 0;
}
+/**
+ * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
+ * It is the server which resolves the dependencies once the CCID has been
+ * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
+ */
+int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
+{
+ struct list_head *fn = &dreq->dreq_featneg;
+ struct dccp_feat_entry *entry;
+ u8 is_local, ccid;
+
+ for (is_local = 0; is_local <= 1; is_local++) {
+ entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
+
+ if (entry != NULL && !entry->empty_confirm)
+ ccid = entry->val.sp.vec[0];
+ else
+ ccid = dccp_feat_default_value(DCCPF_CCID);
+
+ if (dccp_feat_propagate_ccid(fn, ccid, is_local))
+ return -1;
+ }
+ return 0;
+}
+
static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
{
struct dccp_sock *dp = dccp_sk(sk);