发送multipart/form-data内容类型的请求

Question

以下的 HTTP POST 请求使用 multipart/form-data 内容类型发送数据。

-----------------------------27311326571405\r\nContent-Disposition: form-data; name="list"\r\n\r\n8274184\r\n-----------------------------27311326571405\r\nContent-Disposition: form-data; name="list"\r\n\r\n8274174\r\n-----------------------------27311326571405\r\nContent-Disposition: form-data; name="list"\r\n\r\n8274178\r\n-----------------------------27311326571405\r\nContent-Disposition: form-data; name="antirobot"\r\n\r\n2341234\r\n-----------------------------27311326571405\r\nContent-Disposition: form-data; name="votehidden"\r\n\r\n1\r\n-----------------------------27311326571405--\r\n

列表是一个输入名称。8274184、8274174、8274178等是输入值。但是27311326571405、27311326571405等等是什么？我想使用C#发送相同的请求，但我真的不知道在哪里可以得到这些数字。

- Neir0

Answer 1

---27311326571405是界限，它是一个随机字符串，不应该出现在您发送的数据中，并且用作值之间的分隔符。

以下是向给定地址发送此类请求的示例：

class Program
{
    static void Main()
    {
        var data = new List<KeyValuePair<string, string>>(new[]
        {
            new KeyValuePair<string, string>("list", "8274184"),
            new KeyValuePair<string, string>("list", "8274174"),
            new KeyValuePair<string, string>("list", "8274178"),
            new KeyValuePair<string, string>("antirobot", "2341234"),
            new KeyValuePair<string, string>("votehidden", "1"),
        });

        string boundary = "----MyAppBoundary" + DateTime.Now.Ticks.ToString("x");

        var request = (HttpWebRequest)WebRequest.Create("http://example.com");
        request.ContentType = "multipart/form-data; boundary=" + boundary;
        request.Method = "POST";

        using (var requestStream = request.GetRequestStream())
        using (var writer = new StreamWriter(requestStream))
        {
            foreach (var item in data)
            {
                writer.WriteLine("--" + boundary);
                writer.WriteLine(string.Format("Content-Disposition: form-data; name=\"{0}\"", item.Key));
                writer.WriteLine();
                writer.WriteLine(item.Value);
            }
            writer.WriteLine(boundary + "--");
        }

        using (var response = request.GetResponse())
        using (var responseStream = response.GetResponseStream())
        using (var reader = new StreamReader(responseStream))
        {
            Console.WriteLine(reader.ReadToEnd());
        }
    }
}

- Darin Dimitrov

Answer 2

这是一个半随机字符串，用于区分不同的字段。在内容类型头中，它被给定为boundary。

请参见what-are-valid-characters-for-creating-a-multipart-form-boundary。

- mvds

Answer 3

如果您想在响应中删除---27311326571405边界值，请使用以下代码。

var multiplarty = require('multiparty')
var util = require('util')
if ( req.method === 'POST') {
  var form = new multiplarty.Form();
  form.parse(req, function(err, fields, files) {
    res.writeHead(200, {'content-type': 'text/plain'});
    res.write('received upload:\n\n');
    res.end(util.inspect({fields: fields}));
  });

  return;
}

- Ankit kumar