Adding pure python SSL test using asyncio

- Uses thread.capnp
- Follows same format as thread_client.py/thread_server.py and
async_client.py/async_server.py
- Including a basic self signed certificate for testing convenience
- Python 3.7 has a bug cleaning up SSL when using asyncio.run
  https://bugs.python.org/issue36709
  Have a slightly more verbose workaround to do proper cleanup

examples/async_ssl_client.py

@@ -0,0 +1,103 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+
+import asyncio
+import argparse
+import threading
+import time
+import capnp
+import socket
+import ssl
+
+import thread_capnp
+
+capnp.remove_event_loop()
+capnp.create_event_loop(threaded=True)
+
+
+def parse_args():
+  parser = argparse.ArgumentParser(usage='Connects to the Example thread server \
+at the given address and does some RPCs')
+  parser.add_argument("host", help="HOST:PORT")
+
+  return parser.parse_args()
+
+
+class StatusSubscriber(thread_capnp.Example.StatusSubscriber.Server):
+
+  '''An implementation of the StatusSubscriber interface'''
+
+  def status(self, value, **kwargs):
+      print('status: {}'.format(time.time()))
+
+
+async def myreader(client, reader):
+  while True:
+    data = await reader.read(4096)
+    client.write(data)
+
+
+async def mywriter(client, writer):
+  while True:
+    data = await client.read(4096)
+    writer.write(data.tobytes())
+    await writer.drain()
+
+
+async def background(cap):
+  subscriber = StatusSubscriber()
+  promise = cap.subscribeStatus(subscriber)
+  await promise.a_wait()
+
+
+async def main(host):
+  host = host.split(':')
+  addr = host[0]
+  port = host[1]
+
+  # Setup SSL context
+  ctx = ssl.create_default_context(ssl.Purpose.SERVER_AUTH, cafile='selfsigned.cert')
+
+  # Handle both IPv4 and IPv6 cases
+  try:
+    print("Try IPv4")
+    reader, writer = await asyncio.open_connection(
+      addr, port,
+      ssl=ctx,
+    )
+  except:
+    print("Try IPv6")
+    reader, writer = await asyncio.open_connection(
+      addr, port,
+      ssl=ctx,
+      family=socket.AF_INET6
+    )
+
+  # Start TwoPartyClient using TwoWayPipe (takes no arguments in this mode)
+  client = capnp.TwoPartyClient()
+  cap = client.bootstrap().cast_as(thread_capnp.Example)
+
+  # Assemble reader and writer tasks, run in the background
+  coroutines = [myreader(client, reader), mywriter(client, writer)]
+  asyncio.gather(*coroutines, return_exceptions=True)
+
+  # Start background task for subscriber
+  tasks = [background(cap)]
+  asyncio.gather(*tasks, return_exceptions=True)
+
+  # Run blocking tasks
+  print('main: {}'.format(time.time()))
+  await cap.longRunning().a_wait()
+  print('main: {}'.format(time.time()))
+  await cap.longRunning().a_wait()
+  print('main: {}'.format(time.time()))
+  await cap.longRunning().a_wait()
+  print('main: {}'.format(time.time()))
+
+if __name__ == '__main__':
+  # Using asyncio.run hits an asyncio ssl bug
+  # https://bugs.python.org/issue36709
+  #asyncio.run(main(parse_args().host), loop=loop, debug=True)
+  loop = asyncio.get_event_loop()
+  loop.run_until_complete(main(parse_args().host))

examples/async_ssl_server.py

@@ -0,0 +1,94 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+
+import argparse
+import capnp
+
+import thread_capnp
+import asyncio
+import socket
+import ssl
+
+
+class ExampleImpl(thread_capnp.Example.Server):
+
+    "Implementation of the Example threading Cap'n Proto interface."
+
+    def subscribeStatus(self, subscriber, **kwargs):
+        return capnp.getTimer().after_delay(10**9) \
+            .then(lambda: subscriber.status(True)) \
+            .then(lambda _: self.subscribeStatus(subscriber))
+
+    def longRunning(self, **kwargs):
+        return capnp.getTimer().after_delay(3 * 10**9)
+
+
+async def myreader(server, reader):
+    while True:
+        data = await reader.read(4096)
+        # Close connection if 0 bytes read
+        if len(data) == 0:
+            server.close()
+        await server.write(data)
+
+
+async def mywriter(server, writer):
+    while True:
+        data = await server.read(4096)
+        writer.write(data.tobytes())
+        await writer.drain()
+
+
+async def myserver(reader, writer):
+    # Start TwoPartyServer using TwoWayPipe (only requires bootstrap)
+    server = capnp.TwoPartyServer(bootstrap=ExampleImpl())
+
+    # Assemble reader and writer tasks, run in the background
+    coroutines = [myreader(server, reader), mywriter(server, writer)]
+    asyncio.gather(*coroutines, return_exceptions=True)
+
+    await server.poll_forever()
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(usage='''Runs the server bound to the\
+given address/port ADDRESS. ''')
+
+    parser.add_argument("address", help="ADDRESS:PORT")
+
+    return parser.parse_args()
+
+
+async def main():
+    address = parse_args().address
+    host = address.split(':')
+    addr = host[0]
+    port = host[1]
+
+    # Setup SSL context
+    ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
+    ctx.load_cert_chain('selfsigned.cert', 'selfsigned.key')
+
+    # Handle both IPv4 and IPv6 cases
+    try:
+        print("Try IPv4")
+        server = await asyncio.start_server(
+            myserver,
+            addr, port,
+            ssl=ctx,
+        )
+    except:
+        print("Try IPv6")
+        server = await asyncio.start_server(
+            myserver,
+            addr, port,
+            ssl=ctx,
+            family=socket.AF_INET6,
+        )
+
+    async with server:
+        await server.serve_forever()
+
+if __name__ == '__main__':
+    asyncio.run(main())

examples/selfsigned.cert

@@ -0,0 +1,17 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----

examples/selfsigned.key

@@ -0,0 +1,28 @@
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----