Add basic hard coded implementation

tcp_nat_proxy.py

@@ -1,3 +1,40 @@
+import asyncio
+
 import uvloop
 
 uvloop.install()
+
+BUFFER_SIZE = 4096
+
+
+async def pipe(reader, writer):
+    try:
+        while not reader.at_eof():
+            writer.write(await reader.read(BUFFER_SIZE))
+    finally:
+        writer.close()
+
+
+async def create_proxy_pipe(listen_port, destination_host, destination_port):
+    async def handle_client(local_reader, local_writer):
+        try:
+            remote_reader, remote_writer = await asyncio.open_connection(
+                destination_host, destination_port
+            )
+            pipe1 = pipe(local_reader, remote_writer)
+            pipe2 = pipe(remote_reader, local_writer)
+            await asyncio.gather(pipe1, pipe2)
+        finally:
+            local_writer.close()
+
+    server = await asyncio.start_server(handle_client, "0.0.0.0", listen_port)
+    print("Serving on {}".format(server.sockets[0].getsockname()))
+    await server.wait_closed()
+
+
+async def main():
+    await asyncio.gather(create_proxy_pipe(8888, "127.0.0.1", 8889))
+
+
+if __name__ == "__main__":
+    asyncio.run(main())