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如何解决使 pynng 和 socket 相互通信？

TL;DR

我使用 pynng 启动了服务器，然后来自 Python 标准库 socket 的客户端将尝试向其发送消息。

问题是客户端可以发送消息，但服务器却没有注意到。因此，它不起作用。

我错过了什么吗？一些低级协议设置？一些终止符？

我这样做的原因是我将构建一个使用 pynng 作为服务器的 Python 脚本。然后一个非 Python 程序（我假设它了解基本的 TCP 协议）将尝试与这个 Python 服务器通信。因此，我使用了恕我直言我可以操作的最原始的套接字库，即标准库中的 socket 模块。

详情

我将在讨论时展示代码片段，但我会在最后展示完整的最小代码示例。

我正在尝试使用 pynng

def server():
    with pynng.Pair0(Listen=f'tcp://{HOST:s}:{PORT:D}',recv_timeout=10000) as s:
        print("Server running")
        data = s.recv()  # Blocks forever here
        print(data)

然后，看起来像这样的客户端将尝试连接到它：

def clIEnt():
    with socket.create_connection(address=(HOST,PORT),timeout=5) as s:
        print("ClIEnt connected")
        s.sendall(b'Hello world')
        print("ClIEnt sent message")

我将它们放在一起使用 threading：

def main():
    srv = threading.Thread(target=server)
    cli = threading.Thread(target=clIEnt)

    srv.start()
    cli.start()

    srv.join()
    cli.join()

最低工作代码

总而言之，这是最低限度的工作代码：

import socket
import pynng
import threading

HOST = "127.0.0.1"
PORT = 65432

def main():
    srv = threading.Thread(target=server)
    cli = threading.Thread(target=clIEnt)

    srv.start()
    cli.start()

    srv.join()
    cli.join()

def server():
    with pynng.Pair0(Listen=f'tcp://{HOST:s}:{PORT:D}',recv_timeout=10000) as s:
        print("Server running")
        data = s.recv()  # Blocks forever here
        print("message received")
        print(data)

def clIEnt():
    with socket.create_connection(address=(HOST,timeout=5) as s:
        print("ClIEnt connected")
        s.sendall(b'Hello world')
        print("ClIEnt sent message")


if __name__ == "__main__":
    main()

然后我在终端运行这个

$ python main.py

似乎 server 无法recv 发送消息，因此 recv 尝试在 10000 毫秒时超时。

Server running
ClIEnt connected
ClIEnt sent message
Exception in thread Thread-1:
TraceBACk (most recent call last):
  file "/home/kmonisit/miniconda3/envs/engg/lib/python3.8/threading.py",line 932,in _bootstrap_inner
    self.run()
  file "/home/kmonisit/miniconda3/envs/engg/lib/python3.8/threading.py",line 870,in run
    self._target(*self._args,**self._kwargs)
  file "main.py",line 39,in server
    data = s.recv()  # Blocks forever here
  file "/home/kmonisit/miniconda3/envs/engg/lib/python3.8/site-packages/pynng/nng.py",line 454,in recv
    check_err(ret)
  file "/home/kmonisit/miniconda3/envs/engg/lib/python3.8/site-packages/pynng/exceptions.py",line 201,in check_err
    raise exc(String,err)
pynng.exceptions.Timeout: Timed out

解决方法

class Pair0:
    """A poor implementation of the Pair0 protocol"""

    def __init__(self,host,port,timeout=NonE):
        self._sock = socket.create_connection(address=(host,port),timeout=timeout)
        # https://github.com/nanomsg/nanomsg/blob/master/rfc/sp-tcp-mapping-01.txt
        # upon making a connection,both ends are required to send this header
        self._sock.send(b'\x00SP\x00\x00\x10\x00\x00')
        print(self._sock.recv(8))

    def send(self,data):
        # messages are simply "length + payload".  Length is 64-bit in network byte
        # order.
        packed = struct.pack('!Q',len(data))
        self._sock.sendall(packed + data)

    def recv(self):
        size_bytes = self._sock.recv(8)
        (size,) = struct.unpack('!Q',size_bytes)
        received = 0
        parts = []
        while received < size:
            data = self._sock.recv(size - received)
            received += len(data)
            parts.append(data)
        return b''.join(parts)

import socket
import struct
import pynng
import threading
import time

HOST = "127.0.0.1"
PORT = 65432


def main():
    srv = threading.Thread(target=server)

    srv.start()
    # sleep to give the server time to bind to the address
    time.sleep(0.1)
    _client = Pair0(HOST,PORT,1)
    _client.send(b'Hello pynng')
    _client.send(b'hope everything is going well for you')
    print(_client.recv())
    print(_client.recv())
    srv.join()


def server():
    with pynng.Pair0(listen=f'tcp://{HOST:s}:{PORT:D}',recv_timeout=1000) as s:
        print("Server running")
        for _ in range(2):
            data = s.recv()
            print("message received")
            print(data)
        s.send(b'Hello bad client')
        s.send(b'I hope you are doing okay')


class Pair0:
    """A poor implementation of the Pair0 protocol"""

    def __init__(self,size_bytes)
        received = 0
        parts = []
        while received < size:
            data = self._sock.recv(size - received)
            received += len(data)
            parts.append(data)
        return b''.join(parts)


if __name__ == "__main__":
    main()

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