flow: Add helper to determine a flow's protocol

Each flow already has a type field.  This implies the protocol the
flow represents, but also has more information: we have two ways to
represent TCP flows, "tap" and "spliced".  In order to generalise some
of the flow mechanics, we'll need to determine a flow's protocol in
terms of the IP (L4) protocol number.

Introduce a constant table and helper macro to derive this from the flow
type.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/flow.c b/flow.c
index 5e94a7a..beb9749 100644
--- a/flow.c
+++ b/flow.c
@@ -25,6 +25,13 @@ const char *flow_type_str[] = {
 static_assert(ARRAY_SIZE(flow_type_str) == FLOW_NUM_TYPES,
 	      "flow_type_str[] doesn't match enum flow_type");
 
+const uint8_t flow_proto[] = {
+	[FLOW_TCP]		= IPPROTO_TCP,
+	[FLOW_TCP_SPLICE]	= IPPROTO_TCP,
+};
+static_assert(ARRAY_SIZE(flow_proto) == FLOW_NUM_TYPES,
+	      "flow_proto[] doesn't match enum flow_type");
+
 /* Global Flow Table */
 
 /**