udp: Create flows for datagrams from originating sockets

This implements the first steps of tracking UDP packets with the flow table
rather than its own (buggy) set of port maps.  Specifically we create flow
table entries for datagrams received from a socket (PIF_HOST or
PIF_SPLICE).

When splitting datagrams from sockets into batches, we group by the flow
as well as splicesrc.  This may result in smaller batches, but makes things
easier down the line.  We can re-optimise this later if necessary.  For now
we don't do anything else with the flow, not even match reply packets to
the same flow.

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

1 files changed, 25 insertions, 0 deletions

diff --git a/udp_flow.h b/udp_flow.h
new file mode 100644
index 0000000..18af9ac
--- /dev/null
+++ b/udp_flow.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright Red Hat
+ * Author: David Gibson <david@gibson.dropbear.id.au>
+ *
+ * UDP flow tracking data structures
+ */
+#ifndef UDP_FLOW_H
+#define UDP_FLOW_H
+
+/**
+ * struct udp - Descriptor for a flow of UDP packets
+ * @f:		Generic flow information
+ * @ts:		Activity timestamp
+ */
+struct udp_flow {
+	/* Must be first element */
+	struct flow_common f;
+
+	time_t ts;
+};
+
+bool udp_flow_timer(const struct ctx *c, const struct udp_flow *uflow,
+		    const struct timespec *now);
+
+#endif /* UDP_FLOW_H */