Native-Messaging firefox 扩展示例 "ping_pong" 由于 TypeError 而无法正常工作

Question

我正在尝试在 Firefox 扩展中使用本机消息传递。我试图从这个 https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Native_messaging

构建示例

我 copy/pasted 所有代码并完全按照页面上的描述进行设置，它发送 "Ping" 但没有收到 "Pong" 返回。浏览器控制台显示 TypeError: a bytes-like object is required, not 'str'on the line 17 in the python application.我能做什么？

我用windows7和python3.x Web 扩展正在向应用程序发送一个 json 对象，然后测试长度和 struct.unpacks 消息。如果消息是 "ping"，它会尝试 struct.pack 和 json.dumps 响应 "pong"，Web 扩展程序会收到该响应作为响应。消息和任何错误都会写入 console.log.

例子中说：

请注意 运行 python 和 -u 标志在 Windows、

上是必需的

为了保证stdin和stdout是二进制打开的，而是

比文字，模式。

我确实设置了 .bat 启动脚本以包含 -u 标志，但似乎 python 仍然将标准输入读取为字符串，然后在尝试 struct.unpack.

用于发送 ping 的网络扩展 background.js：

/*
On startup, connect to the "ping_pong" app.
*/
var port = browser.runtime.connectNative("ping_pong");

/*
Listen for messages from the app.
*/
port.onMessage.addListener((response) => {
  console.log("Received: " + response);
});

/*
On a click on the browser action, send the app a message.
*/
browser.browserAction.onClicked.addListener(() => {
  console.log("Sending:  ping");
  port.postMessage("ping");
});

python 接收 ping 和发送 pong 的应用程序：

#!/usr/bin/python -u

# Note that running python with the `-u` flag is required on Windows,
# in order to ensure that stdin and stdout are opened in binary, rather
# than text, mode.

import json
import sys
import struct


# Read a message from stdin and decode it.
def get_message():
    raw_length = sys.stdin.read(4)
    if not raw_length:
        sys.exit(0)
    message_length = struct.unpack('=I', raw_length)[0]
    message = sys.stdin.read(message_length)
    return json.loads(message)


# Encode a message for transmission, given its content.
def encode_message(message_content):
    encoded_content = json.dumps(message_content)
    encoded_length = struct.pack('=I', len(encoded_content))
    return {'length': encoded_length, 'content': encoded_content}


# Send an encoded message to stdout.
def send_message(encoded_message):
    sys.stdout.write(encoded_message['length'])
    sys.stdout.write(encoded_message['content'])
    sys.stdout.flush()


while True:
    message = get_message()
    if message == "ping":
        send_message(encode_message("pong"))

这是给出类型错误的行：

message_length = struct.unpack('=I', raw_length)[0]

日志应该说： 发送：ping 收到：乒乓

日志实际上说： 发送：ping

stderr output from native app ping_pong: Traceback (most recent call last):
stderr output from native app ping_pong:   File "C:\Users\ping_pong\ping_pong.py", line 37, in <module>
stderr output from native app ping_pong:     message = get_message()
stderr output from native app ping_pong:   File "C:\Users\ping_pong\ping_pong.py", line 17, in get_message
stderr output from native app ping_pong:     message_length = struct.unpack('=I', raw_length)[0]
stderr output from native app ping_pong: TypeError: a bytes-like object is required, not 'str'

Answer 1

使用 Python 2 对我来说效果很好（在 Linux 上）。

#!/usr/bin/python2 -u

或

path\to\python2

分别在windows批处理文件中。

要使其在 Python 3 中工作，您需要将编码后的字符串打包到一个结构中（我不知道为什么 - 但它确实有效）：

#!/usr/bin/python -u

# Note that running python with the `-u` flag is required on Windows,
# in order to ensure that stdin and stdout are opened in binary, rather
# than text, mode.

import json
import sys
import struct


# Read a message from stdin and decode it.
def get_message():

    # use buffer to get bytes
    raw_length = sys.stdin.buffer.read(4)


    #raise ValueError(raw_length)

    if not raw_length:
        sys.exit(0)
    message_length = struct.unpack('=I', raw_length)[0]
    message = sys.stdin.buffer.read(message_length).decode("utf-8")
    return json.loads(message)


# Encode a message for transmission, given its content.
def encode_message(message_content):
    encoded_content = json.dumps(message_content).encode("utf-8")
    encoded_length = struct.pack('=I', len(encoded_content))
    return {'length': encoded_length, 'content': struct.pack(str(len(encoded_content))+"s",encoded_content)}


# Send an encoded message to stdout.
def send_message(encoded_message):
    #raise ValueError(encoded_message)
    sys.stdout.buffer.write(encoded_message['length'])
    sys.stdout.buffer.write(encoded_message['content'])
    sys.stdout.buffer.flush()


while True:
    message = get_message()
    if message == "ping":
        send_message(encode_message("pong"))