c# - 将 C# 转换为 NodeJS

Question

您好，我正在尝试将此 C# 函数转换为 NodeJS，但它不起作用我真的不知道哪里出了问题让我展示一些代码和输出

C#:

private static byte[] ConvertMsg(byte[] message, byte type = 255, byte cmd = 255)
{
    int msgLength = message.Length;
    byte[] bArray = new byte[msgLength + 3];
    bArray[0] = type;
    bArray[1] = cmd;
    Buffer.BlockCopy(message, 0, bArray, 2, msgLength);
    bArray[msgLength + 2] = 0;
    return bArray;
}

static void Main()
{

    byte[] encrypted = ConvertMsg(Encoding.Default.GetBytes("hi"),3,3);
    Console.WriteLine($"Encrypted: {Convert.ToBase64String(encrypted)}");

    Console.ReadKey();
}

输出:

AwNoaQA=

Node :

function ConvertMsg(message, type=255, cmd=255){
    let length = message.length;
    let bArray = Buffer.alloc(length+3);
    bArray[0] = type;
    bArray[1] = cmd;

    bArray.copy(message,0,length);

    bArray[length + 2] = 0;
    return bArray;
}

let encrypted = ConvertMsg(Buffer.from("hi"),3,3);
console.log(encrypted.toString("base64"));

输出:

AwMAAAA=

如您所见，输出不一样，非常感谢任何帮助，请在回答时解释我想了解更多，谢谢。

Answer 1

根据 Buffer documentation , .copy(target[, targetStart[, sourceStart[, sourceEnd]]])

Copies data from a region of buf to a region in target even if the target memory region overlaps with buf.

这里

// means copy 'bArray' starting from length to 'message' starting from 0
bArray.copy(message, 0, length); 

您不要复制 message 的内容至 bArray .你做相反的事情 - 你复制 bArray内容，即 [3, 3, 0, 0, 0]现在到message ，并实际覆盖您的消息。

然后，你输出这个bArray ，结果为 AwMAAAA=这是 [3, 3, 0, 0, 0] 的 Base64 表示.

您可能希望以这种方式更改您的功能:

function ConvertMsg(message, type=255, cmd=255){
    let length = message.length;
    let bArray = Buffer.alloc(length + 3);

    bArray[0] = type;
    bArray[1] = cmd;

    // means copy 'message' starting from 0 to 'bArray' starting from 2
    message.copy(bArray, 2);

    bArray[length + 2] = 0;
    return bArray;
}