dccp: Basic data structure for feature negotiation
This patch prepares for the new and extended feature-negotiation routines.
The following feature-negotiation data structures are provided:
* a container for the various (SP or NN) values,
* symbolic state names to track feature states,
* an entry struct which holds all current information together,
* elementary functions to fill in and process these structures.
Entry structs are arranged as FIFO for the following reason: RFC 4340 specifies
that if multiple options of the same type are present, they are processed in the
order of their appearance in the packet; which means that this order needs to be
preserved in the local data structure (the later insertion code also respects
this order).
The struct list_head has been chosen for the following reasons: the most
frequent operations are
* add new entry at tail (when receiving Change or setting socket options);
* delete entry (when Confirm has been received);
* deep copy of entire list (cloning from listening socket onto request socket).
The NN value has been set to 64 bit, which is a currently sufficient upper limit
(Sequence Window feature has 48 bit).
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 933a0ec..94a81b8 100644
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -23,6 +23,20 @@
#define DCCP_FEAT_SP_NOAGREE (-123)
+/* copy constructor, fval must not already contain allocated memory */
+static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
+{
+ fval->sp.len = len;
+ if (fval->sp.len > 0) {
+ fval->sp.vec = kmemdup(val, len, gfp_any());
+ if (fval->sp.vec == NULL) {
+ fval->sp.len = 0;
+ return -ENOBUFS;
+ }
+ }
+ return 0;
+}
+
int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
u8 *val, u8 len, gfp_t gfp)
{