尝试将文件从C＃客户端发送到node.js TCP服务器

Question

I have the following code:

C# client:

class Program
{
    static void Main(string[] args)
    {
        var client = new TcpClient(AddressFamily.InterNetwork);

        client.Connect("127.0.0.1", 9090);

        byte[] buffer = Encoding.Default.GetBytes(Program.ReadFile(@"C:\pub\image.jpg"));

        using (var stream = client.GetStream())
        {
            stream.Write(buffer, 0, buffer.Length);
        }

        Console.WriteLine("File sent.");

        Console.ReadLine();
    }

    public static string ReadFile(string path)
    {
        string content = string.Empty;

        using (var stream = new FileStream(path, FileMode.Open))
        {
            using (var reader = new StreamReader(stream))
            {
                content = reader.ReadToEnd();
            }
        }

        return content;
    }
}

node.js server:

var net = require('net');
var fs = require('fs');

var server = net.createServer(function (socket)
{
    var buffer = new Buffer(0, 'binary');

    socket.on('data', function (data)
    {
        buffer = Buffer.concat([buffer, new Buffer(data, 'binary')]);
    });

    socket.on("end", function (data)
    {
        fs.writeFile("image.jpg", buffer);
        buffer = new Buffer(0, 'binary');
    });
});

server.listen(9090, '127.0.0.1');

This doesn't work. The file always arrives corrupt. What am I doing wrong?

Answer 1

This is most probabbly encoding issue.

I would try to do:

1) in C# : Encoding.UTF8.GetBytes(Program.ReadFile(@"C:\\pub\\image.jpg")); //EXPLICITLY SPECIFY UTF8 ENCODING Encoding.UTF8.GetBytes(Program.ReadFile(@"C:\\pub\\image.jpg")); //EXPLICITLY SPECIFY UTF8 ENCODING

and

2) in JS : var buffer = new Buffer(0);

as, according to the node.js documentation :

Allocates a new buffer containing the given str. encoding defaults to 'utf8'.

Hope this helps.

Answer 2

Your problem is on how you are reading the file in C#. If you write back the file to disk from C# you can see how the number of bytes does not match:

// This code does not work
// the number of bytes in image2.jpg won't match image.jpg
byte[] buffer = Encoding.Default.GetBytes(Program.ReadFile(@"C:\pub\image.jpg"));
File.WriteAllBytes(@"c:\pub\image2.jpg", buffer);

Change your read to use the native C# ReadAllBytes instead:

// This works 
// the number of bytes in image2.jpg will match image.jpg
byte[] buffer = File.ReadAllBytes(@"C:\temp\file.jpg");
File.WriteAllBytes(@"c:\pub\image2.jpg", buffer);

Your Node.js code is correct and works once you send it the correct bytes from C#.