From 552660e9dba43218ebd5bc0a572bd71a4668dcbe Mon Sep 17 00:00:00 2001
From: Joel Bender <joel@carrickbender.com>
Date: Thu, 29 Mar 2018 00:12:37 -0400
Subject: [PATCH] sample NAT router (no peers)

---
 samples/NATRouter.py | 139 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100755 samples/NATRouter.py

diff --git a/samples/NATRouter.py b/samples/NATRouter.py
new file mode 100755
index 0000000..fa9b70c
--- /dev/null
+++ b/samples/NATRouter.py
@@ -0,0 +1,139 @@
+#!/usr/bin/env python
+
+"""
+This sample application presents itself as a router between an "inside" network
+that sits behind a NAT and a "global" network of other NAT router peers.
+
+$ python NATRouter.py addr1 port1 net1 addr2 port2 net2
+
+    addr1       - local address like 192.168.1.10/24
+    port1       - local port
+    net1        - local network number
+    addr2       - global address like 201.1.1.1:47809
+    port2       - local mapped port
+    net2        - global network number
+
+The sample addresses are like running BR1 from Figure J-8, Clause J.7.5.
+"""
+
+from bacpypes.debugging import bacpypes_debugging, ModuleLogger
+from bacpypes.consolelogging import ArgumentParser
+
+from bacpypes.core import run
+from bacpypes.comm import bind
+
+from bacpypes.pdu import Address
+from bacpypes.netservice import NetworkServiceAccessPoint, NetworkServiceElement
+from bacpypes.bvllservice import BIPBBMD, BIPNAT, AnnexJCodec, UDPMultiplexer
+
+# some debugging
+_debug = 0
+_log = ModuleLogger(globals())
+
+#
+#   NATRouter
+#
+
+@bacpypes_debugging
+class NATRouter:
+
+    def __init__(self, addr1, port1, net1, addr2, port2, net2):
+        if _debug: NATRouter._debug("__init__ %r %r %r %r %r %r", addr1, port1, net1, addr2, port2, net2)
+
+        # a network service access point will be needed
+        self.nsap = NetworkServiceAccessPoint()
+
+        # give the NSAP a generic network layer service element
+        self.nse = NetworkServiceElement()
+        bind(self.nse, self.nsap)
+
+        #== First stack
+
+        # local address
+        local_addr = Address("{}:{}".format(addr1, port1))
+
+        # create a BBMD stack
+        self.s1_bip = BIPBBMD(local_addr)
+        self.s1_annexj = AnnexJCodec()
+        self.s1_mux = UDPMultiplexer(local_addr)
+
+        # bind the bottom layers
+        bind(self.s1_bip, self.s1_annexj, self.s1_mux.annexJ)
+
+        # bind the BIP stack to the local network
+        self.nsap.bind(self.s1_bip, net1, addr1)
+
+        #== Second stack
+
+        # global address
+        global_addr = Address(addr2)
+        nat_addr = Address("{}:{}".format(addr1, port2))
+
+        # create a NAT stack
+        self.s2_bip = BIPNAT(global_addr)
+        self.s2_annexj = AnnexJCodec()
+        self.s2_mux = UDPMultiplexer(nat_addr)
+
+        # bind the bottom layers
+        bind(self.s2_bip, self.s2_annexj, self.s2_mux.annexJ)
+
+        # bind the BIP stack to the global network
+        self.nsap.bind(self.s2_bip, net2)
+
+#
+#   __main__
+#
+
+def main():
+    # parse the command line arguments
+    parser = ArgumentParser(description=__doc__)
+
+    # add an argument for local address
+    parser.add_argument('addr1', type=str,
+          help='address of first network',
+          )
+
+    # add an argument for local port
+    parser.add_argument('port1', type=int,
+          help='port number of local network',
+          )
+
+    # add an argument for interval
+    parser.add_argument('net1', type=int,
+          help='network number of local network',
+          )
+
+    # add an argument for interval
+    parser.add_argument('addr2', type=str,
+          help='address of global network (outside NAT)',
+          )
+
+    # add an argument for local port
+    parser.add_argument('port2', type=int,
+          help='port number of global forwarded port',
+          )
+
+    # add an argument for interval
+    parser.add_argument('net2', type=int,
+          help='network number of global network',
+          )
+
+    # now parse the arguments
+    args = parser.parse_args()
+
+    if _debug: _log.debug("initialization")
+    if _debug: _log.debug("    - args: %r", args)
+
+    # create the router
+    router = NATRouter(args.addr1, args.port1, args.net1, args.addr2, args.port2, args.net2)
+    if _debug: _log.debug("    - router: %r", router)
+
+    _log.debug("running")
+
+    run()
+
+    _log.debug("fini")
+
+
+if __name__ == "__main__":
+    main()