sockets - 在 SSL 连接中使用异步 sock_recv 时出现 SSLWantReadError

Question

我正在使用套接字和 asyncio 在服务器实现中实现生产者-消费者程序。问题是异步函数 sock_recv() 在与包裹在 ssl 连接中的套接字一起使用时似乎无法正常工作。以下是工作代码。

服务器端

import asyncio
import random
import socket
import ssl

SERVER_ADDRESS = (HOST, PORT) = "127.0.0.1", 8881

async def producer(queue, client_connection, event_loop):
    while True:
        print("Waiting for sock_recv")
        await event_loop.sock_recv(client_connection, 4096)
        r = random.randint(1,101)
        print("Produced: %d" % r)
        await queue.put(r)
        await asyncio.sleep(0)

async def consumer(queue):
    while True:
        print("Wating for queue.get()")
        r = await queue.get()
        await asyncio.sleep(2)
        print("Consumed: %d" % r)

async def main():
    listen_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    listen_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    listen_socket.bind(SERVER_ADDRESS)
    listen_socket.listen(5)
    ssl_context = ssl.create_default_context(purpose=ssl.Purpose.CLIENT_AUTH)
    ssl_context.load_cert_chain(certfile="certificate.pem", keyfile="key.pem")
    client_connection, client_address = listen_socket.accept()
    # client_connection = ssl_context.wrap_socket(
    #     client_connection, server_side=True
    # )
    client_connection.setblocking(False)
    queue = asyncio.Queue()
    t1 = asyncio.create_task(producer(queue, client_connection, asyncio.get_event_loop()))
    t2 = asyncio.create_task(consumer(queue))
    await asyncio.wait([t1, t2])

event_loop = asyncio.get_event_loop()
asyncio.run(main())

客户端

import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("127.0.0.1", 8881))
s.sendall(b"Hello")

输出

等待 sock_recv
等待 queue.get()
出品:49
等待 sock_recv
消耗:49
等待 queue.get()

这是问题所在，当我取消注释以下部分时

# client_connection = ssl_context.wrap_socket(
#     client_connection, server_side=True
# )

它阻塞在 sock_recv() 函数上。使用未注释的代码，我得到以下输出:

输出

等待 sock_recv
等待 queue.get()

客户端代码

import socket
import ssl

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock = ssl.wrap_socket(s)
sock.connect(("127.0.0.1", 8881))
sock.sendall(b"Hello")

最后，当我用 ctrl-c 关闭服务器时。我得到以下输出

^CTask exception was never retrieved
future: <Task finished coro=<producer() done, defined at asyncio_test.py:8> exception=SSLWantReadError(2, 'The operation did not complete (read) (_ssl.c:2488)')>
Traceback (most recent call last):
  File "asyncio_test.py", line 11, in producer
    await event_loop.sock_recv(client_connection, 4096)
  File "/home/coverfox/.pyenv/versions/3.7.3/lib/python3.7/asyncio/selector_events.py", line 352, in sock_recv
    return await fut
  File "/home/coverfox/.pyenv/versions/3.7.3/lib/python3.7/asyncio/selector_events.py", line 366, in _sock_recv
    data = sock.recv(n)
  File "/home/coverfox/.pyenv/versions/3.7.3/lib/python3.7/ssl.py", line 1037, in recv
    return self.read(buflen)
  File "/home/coverfox/.pyenv/versions/3.7.3/lib/python3.7/ssl.py", line 913, in read
    return self._sslobj.read(len)
ssl.SSLWantReadError: The operation did not complete (read) (_ssl.c:2488)
Traceback (most recent call last):
  File "asyncio_test.py", line 42, in <module>
    asyncio.run(main())
  File "/home/coverfox/.pyenv/versions/3.7.3/lib/python3.7/asyncio/runners.py", line 43, in run
    return loop.run_until_complete(main)
  File "/home/coverfox/.pyenv/versions/3.7.3/lib/python3.7/asyncio/base_events.py", line 571, in run_until_complete
    self.run_forever()
  File "/home/coverfox/.pyenv/versions/3.7.3/lib/python3.7/asyncio/base_events.py", line 539, in run_forever
    self._run_once()
  File "/home/coverfox/.pyenv/versions/3.7.3/lib/python3.7/asyncio/base_events.py", line 1739, in _run_once
    event_list = self._selector.select(timeout)
  File "/home/coverfox/.pyenv/versions/3.7.3/lib/python3.7/selectors.py", line 468, in select
    fd_event_list = self._selector.poll(timeout, max_ev)
KeyboardInterrupt

编辑:我刚刚发现，如果我在客户端代码的 wrap_socket() 函数中传递 do_handshake_on_connect=False 它会起作用，但 ssl 将不起作用。

Answer 1

因此，异步函数 sock_recv() 不支持 SSLSocket，因为 SSL 需要写入用户空间缓冲区，如 SO answer 中所述.
解决此问题的方法是在 asyncio 中使用传输或流。这是上述问题中代码的工作版本。

import asyncio
import random
import socket
import ssl

SERVER_ADDRESS = (HOST, PORT) = "127.0.0.1", 8881

async def producer(reader, writer, queue):
    while True:
        print("Waiting for sock_recv")
        await reader.read(16)
        r = random.randint(1,101)
        print("Produced: %d" % r)
        await queue.put(r)
        await asyncio.sleep(0)

async def consumer(queue):
    while True:
        print("Wating for queue.get()")
        r = await queue.get()
        await asyncio.sleep(2)
        print("Consumed: %d" % r)

async def set_up_producer_consumer(reader, writer):
    queue = asyncio.Queue()
    t1 = asyncio.create_task(producer(reader, writer, queue))
    t2 = asyncio.create_task(consumer(queue))
    await asyncio.wait([t1, t2])

async def main():
    ssl_context = ssl.create_default_context(purpose=ssl.Purpose.CLIENT_AUTH)
    ssl_context.load_cert_chain(certfile="certificate.pem", keyfile="key.pem")

    server = await asyncio.start_server(set_up_producer_consumer, HOST, PORT, family=socket.AF_INET, ssl=ssl_context, reuse_address=True)
    await server.wait_closed()

event_loop = asyncio.get_event_loop()
asyncio.run(main())