Error writing MIME multipart body part to output stream
System.IO.IOException
According to the internet it can have many reasons, in my case it was a simple semicolon.
The problem is actually in the client code. It is a semicolon after the form data !
i marked it red ! if it's in the code the servers throws an exception at:
- await Request.Content.ReadAsMultipartAsync(provider);
if you remove it it works perfectly. other server implementation don't have a problem with the semicolon.....
UseCases:
- C# Client to upload files and formdata
- C# Self hostet WebApi2 rest server
Client code:
---------------------------------------------------------------------------------------
private static string UploadFiles(string url, NameValueCollection values, NameValueCollection files = null)
{
string boundary = "----------------------------" + DateTime.Now.Ticks.ToString("x");
// The first boundary
byte[] boundaryBytes = System.Text.Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");
// The last boundary
byte[] trailer = System.Text.Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");
// The first time it itereates, we need to make sure it doesn't put too many new paragraphs down or it completely messes up poor webbrick
byte[] boundaryBytesF = System.Text.Encoding.ASCII.GetBytes("--" + boundary + "\r\n");
try
{
// Create the request and set parameters
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.ContentType = "multipart/form-data; boundary=" + boundary;
request.Method = "POST";
request.KeepAlive = true;
request.SendChunked = true;
// Get request stream
Stream requestStream = request.GetRequestStream();
foreach (string key in values.Keys)
{
// Write item to stream
byte[] formItemBytes = System.Text.Encoding.UTF8.GetBytes(string.Format("Content-Disposition: form-data; name=\"{0}\";\r\n\r\n{1}", key, values[key]));
requestStream.Write(boundaryBytes, 0, boundaryBytes.Length);
requestStream.Write(formItemBytes, 0, formItemBytes.Length);
}
if (files != null)
{
foreach (string key in files.Keys)
{
if (File.Exists(files[key]))
{
int bytesRead = 0;
byte[] buffer = new byte[2048];
string filename = new FileInfo(files[key]).Name;
byte[] formItemBytes = System.Text.Encoding.UTF8.GetBytes(string.Format("Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: application/octet-stream\r\n\r\n", key, filename));
requestStream.Write(boundaryBytes, 0, boundaryBytes.Length);
requestStream.Write(formItemBytes, 0, formItemBytes.Length);
using (FileStream fileStream = new FileStream(files[key], FileMode.Open, FileAccess.Read))
{
while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
{
// Write file content to stream, byte by byte
requestStream.Write(buffer, 0, bytesRead);
}
fileStream.Close();
}
}
}
}
// Write trailer and close stream
requestStream.Write(trailer, 0, trailer.Length);
requestStream.Close();
using (StreamReader reader = new StreamReader(request.GetResponse().GetResponseStream()))
{
return reader.ReadToEnd();
};
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
return "";
}
Server Code:
--------------------------------------------------------------------------------------------------------------
public class UploadController : UtilityController
{
[HttpPost]
public async Task PostFormData()
{
// Check if the request contains multipart/form-data.
if (!Request.Content.IsMimeMultipartContent())
{
throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);
}
string root = Parameters.Get("UploadPath", Path.GetTempPath().EnsureBS(), "Files");
var provider = new MultipartFormDataStreamProvider(root);
try
{
// throws exception next line !!!!
await Request.Content.ReadAsMultipartAsync(provider);
// This illustrates how to get the file names.
foreach (MultipartFileData file in provider.FileData)
{
Trace.WriteLine(file.Headers.ContentDisposition.FileName);
Trace.WriteLine("Server file path: " + file.LocalFileName);
}
return Request.CreateResponse(HttpStatusCode.OK);
}
catch (System.Exception e)
{
return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, e);
}
}
}
