dccp: Query supported CCIDs
This provides a data structure to record which CCIDs are locally supported
and three accessor functions:
- a test function for internal use which is used to validate CCID requests
made by the user;
- a copy function so that the list can be used for feature-negotiation;
- documented getsockopt() support so that the user can query capabilities.
The data structure is a table which is filled in at compile-time with the
list of available CCIDs (which in turn depends on the Kconfig choices).
Using the copy function for cloning the list of supported CCIDs is useful for
feature negotiation, since the negotiation is now with the full list of available
CCIDs (e.g. {2, 3}) instead of the default value {2}. This means negotiation
will not fail if the peer requests to use CCID3 instead of CCID2.
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>
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 484b8a1..d3ac1bd 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -209,6 +209,7 @@
#define DCCP_SOCKOPT_SERVER_TIMEWAIT 6
#define DCCP_SOCKOPT_SEND_CSCOV 10
#define DCCP_SOCKOPT_RECV_CSCOV 11
+#define DCCP_SOCKOPT_AVAILABLE_CCIDS 12
#define DCCP_SOCKOPT_CCID_RX_INFO 128
#define DCCP_SOCKOPT_CCID_TX_INFO 192