我如何使用shell脚本的浏览器本地消息传递主机应用程序 [英] How do I use a shell-script as Chrome Native Messaging host application

问题描述

你如何处理铬本地消息API调用一个bash脚本？

How do you process a Chrome Native Messaging API-call with a bash script?

我成功地使用Python与<一做href=\"http://src.chromium.org/viewvc/chrome/trunk/src/chrome/common/extensions/docs/examples/api/nativeMessaging/\"相对=nofollow>这个例子

I succeeded in doing it with python with this example

当然，我可以叫庆典从Python code。与子，但有可能跳过Python和处理的消息庆典直接？

Sure I can call bash from the python code with subprocess, but is it possible to skip python and process the message in bash directly?

在问题部分读取JSON序列信息到一个变量。该消息被使用JSON，UTF-8 EN codeD序列化是preceded通过标准输入本地字节序32位的消息长度。

The problematic part is reading the JSON serialized message into a variable. The message is serialized using JSON, UTF-8 encoded and is preceded with 32-bit message length in native byte order through stdin.

回声$ * 仅输出：
铬扩展：// knldjmfmopnpolahpmmgbagdohdnhkik /

另外像

read
echo $REPLY

不输出任何东西。 JSON的消息的迹象。 Python使用 struct.unpack 这一点。可以在庆典？

推荐答案

我建议不使用（bash）的shell脚本作为本地消息主机，因为bash的太有限了是有用的。

I suggest to not use (bash) shell scripts as a native messaging host, because bash is too limited to be useful.

读不带任何参数读取终止前一整行，而的本地消息协议指定前四个字节指定下列消息长度（以本地字节顺序）。

read without any parameters reads a whole line before terminating, while the native messaging protocol specifies that the first four bytes specify the length of the following message (in native byte order).

Bash是处理二进制数据的可怕工具。你的读命令的一个改进版本将指定 -nñ参数来停止后阅读ñ字符（注意：不是字节）和 -r 删除一些处理。例如。以下将前四个字符存储在一个名为变量 var_ preFIX ：

Bash is a terrible tool for processing binary data. An improved version of your read command would specify the -n N parameter to stop reading after N characters (note: not bytes) and -r to remove some processing. E.g. the following would store the first four characters in a variable called var_prefix:

IFS= read -rn 4 var_prefix

即使你假定这个存储变量中的前四个字节（不是！），那么你必须字节转换为整数。难道我已经提到的bash自动删除所有的NUL字节？这使得特征猛砸，作为一个完全有能力的本地消息主机一钱不值。

Even if you assume that this stores the first four bytes in the variable (it does not!), then you have to convert the bytes to an integer. Did I already mention that bash automatically drops all NUL bytes? This characteristics makes Bash utterly worthless for being a fully capable native messaging host.

您可以忽略前几个字节有这个缺点应对，并开始当你发现一个 {字符时，JSON格式的请求开始分析的结果。在此之后，你必须阅读所有的输入，直到输入端找到。你需要一个JSON解析器，停止读取输入时，它遇到的JSON字符串的结尾。祝你好运与编写。

You could cope with this shortcoming by ignoring the first few bytes, and start parsing the result when you spot a { character, the beginning of the JSON-formatted request. After this, you have to read all input until the end of the input is found. You need a JSON parser that stops reading input when it encounters the end of the JSON string. Good luck with writing that.

生成的输出是一个更简单，只需使用回声-n 或 的printf 。

Generating output is a easier, just use echo -n or printf.

下面是假定输入以} ，读取它（不处理）结束，并用结果回答一个最小的例子。虽然这个演示的作品，我强烈建议不要使用bash，但更丰富的（脚本）语言如Python或C ++。

Here is a minimal example that assumes that the input ends with a }, reads it (without processing) and replies with a result. Although this demo works, I strongly recommend to not use bash, but a richer (scripting) language such as Python or C++.

#!/bin/bash
# Loop forever, to deal with chrome.runtime.connectNative
while IFS= read -r -n1 c; do
    # Read the first message
    # Assuming that the message ALWAYS ends with a },
    # with no }s in the string. Adopt this piece of code if needed.
    if [ "$c" != '}' ] ; then
        continue
    fi

    message='{"message": "Hello world!"}'
    # Calculate the byte size of the string.
    # NOTE: This assumes that byte length is identical to the string length!
    # Do not use multibyte (unicode) characters, escape them instead, e.g.
    # message='"Some unicode character:\u1234"'
    messagelen=${#message}

    # Convert to an integer in native byte order.
    # If you see an error message in Chrome's stdout with
    # "Native Messaging host tried sending a message that is ... bytes long.",
    # then just swap the order, i.e. messagelen1 <-> messagelen4 and
    # messagelen2 <-> messagelen3
    messagelen1=$(( ($messagelen      ) & 0xFF ))               
    messagelen2=$(( ($messagelen >>  8) & 0xFF ))               
    messagelen3=$(( ($messagelen >> 16) & 0xFF ))               
    messagelen4=$(( ($messagelen >> 24) & 0xFF ))               

    # Print the message byte length followed by the actual message.
    printf "$(printf '\\x%x\\x%x\\x%x\\x%x' \
        $messagelen1 $messagelen2 $messagelen3 $messagelen4)%s" "$message"

done

这篇关于我如何使用shell脚本的浏览器本地消息传递主机应用程序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！