节点js中的PHP函数

Question

试图将以下PHP函数转换为Node.js，但两者均显示不同的输出。out.node.js函数应该与PHP相等。以下是我尝试过的代码。我还附加了hexdump值。

PHP

function hextobin() {

    $hexString = 'd41d8cd98f00b204e9800998ecf8427e';
    $length = strlen($hexString);
    $binString = "";
    $count = 0;
    while ($count < $length) {
        $subString = substr($hexString, $count, 2);
        $packedString = pack("H*", $subString);

        if ($count == 0) {
            $binString = $packedString;
        } else {
            $binString .= $packedString;
        }

        $count += 2;
    }
    return $binString;
}

Output = ��ُ�� ���B~

Hexdump -C value of above output = 

00000000  ef bf bd 1d ef bf bd d9  8f ef bf bd 04 ef bf bd  |................|
00000010  20 ef bf bd ef bf bd ef  bf bd 42 7e 0a           | .........B~.|
0000001d

Node.JS

exports.hex2bin = () => {
    let hexString = 'd41d8cd98f00b204e9800998ecf8427e';
    let binString ="";
    let length = hexString.length;
    let count = 0;

    while (count < length) {

        const sub = hexString.substr(count, 2);
        let packedString =  Buffer.from(sub, "hex");

        if (count === 0) {
            binString = packedString;
        } else {
            binString += packedString;
        }

        count += 2;
    }

    return binString;
};

Output = ������� ���B~

Hexdump -C value of above output = 

00000000  ef bf bd 1d ef bf bd ef  bf bd ef bf bd ef bf bd  |................|
00000010  04 ef bf bd ef bf bd 20  ef bf bd ef bf bd ef bf  |....... ........|
00000020  bd 42 7e 0a                                       |.B~.|
00000024

任何帮助将不胜感激。

Answer 1

在PHP中，字符串没有内部编码。它只是一系列字节。在Javascript中，字符串为UTF-16。为了处理等同于节点中php字符串的内容，Buffer类已经是一个无符号8位字节的数组。您正在使用的实用程序函数将一次性读取整个十六进制字符串，而不是转换每对十六进制字符。

概念证明：

let hex2bin = () => {
    let hexString = 'd41d8cd98f00b204e9800998ecf8427e';
    let packedString =  Buffer.from(hexString, "hex");
    return packedString.toString(undefined);
};

let foo = hex2bin();
console.log(foo);

hexdump

$ node test.js | hexdump -C
00000000  ef bf bd 1d ef bf bd d9  8f 00 ef bf bd 04 ef bf  |................|
00000010  bd 09 ef bf bd ef bf bd  ef bf bd 42 7e 0a        |...........B~.|
0000001e