test(nat): Add tests for static NAT + {masquerade, port forwarding}

Add unit tests to validate the use in a pipeline of static NAT +
masquerade, or static NAT + port forwarding, on opposite sides of a
peering.

We set up a pipeline, create a packet, process it, and check for its
output; then we create a fake reply, process it, check as well; at last,
we re-process the original packet, to make sure that the connection
still works after the flow table entry has been created.

Signed-off-by: Quentin Monnet <qmo@qmon.net>

Author: qmonnet

nat/src/lib.rs

@@ -30,6 +30,7 @@ pub mod portfw;
 mod ranges;
 pub mod stateful;
 pub mod stateless;
+mod test;
 
 pub use icmp_handler::nf::IcmpErrorHandler;
 pub use port::NatPort;

nat/src/portfw/portfwtable/access.rs

@@ -4,8 +4,10 @@
 //! Port forwarding table objects for concurrent accesses
 //! from datapath and configuration / management
 
+use super::super::build_port_forwarding_configuration;
 use super::PortFwTableError;
 use super::objects::{PortFwEntry, PortFwTable};
+use config::external::overlay::vpc::ValidatedVpcTable;
 use left_right::{Absorb, ReadGuard, ReadHandle, ReadHandleFactory, WriteHandle};
 
 #[allow(unused)]
@@ -57,6 +59,14 @@ impl PortFwTableWriter {
         self.0.publish(); // intended
         Ok(())
     }
+    pub fn update_from_vpc_table(
+        &mut self,
+        vpc_table: &ValidatedVpcTable,
+    ) -> Result<(), PortFwTableError> {
+        let ruleset = build_port_forwarding_configuration(vpc_table)
+            .map_err(|e| PortFwTableError::Unsupported(e.to_string()))?;
+        self.update_table(&ruleset)
+    }
 }
 
 #[derive(Debug)]