Send large file from WebAPI. Continent Length is 0

Question

I am trying to send a large file (GB) from one WebAPI (.NET Core) to another WebApi (.Net Core).

I have already managed to send the smaller file as part of the Multipart request, as in the last post here: link

To send a larger file, I need (I think) to send this file as StreamContent, but I get Content length = 0 in the API that receives the request.

The problem arises even when I send (for the test) smaller files (10 MB).

Client code:

    [HttpPost("UploadFiles")]
    public async Task<IActionResult> Post(IFormFile file)
    {
        var filePath = Path.GetTempFileName();

        using (var stream = new FileStream(filePath, FileMode.Create, FileAccess.ReadWrite))
        {
            await file.CopyToAsync(stream);
            using (var formDataContent = new MultipartFormDataContent())
            {
                using (var httpClient = new HttpClient())
                {
                    formDataContent.Add(CreateFileContent(stream, "myfile.test", "application/octet-stream"));

                    var response = await httpClient.PostAsync(
                        "http://localhost:56595/home/upload",
                        formDataContent);

                    return Json(response);
                }
            }
        }
    }

    internal static StreamContent CreateFileContent(Stream stream, string fileName, string contentType)
    {
        var fileContent = new StreamContent(stream);
        fileContent.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("form-data")
        {
            Name = "\"file\"",
            FileName = "\"" + fileName + "\"",
        };
        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(contentType);
        return fileContent;
    }

Server Code:

    [HttpPost]
    public ActionResult Upload()
    {
        IFormFile fileFromRequest = Request.Form.Files.First();

        string myFileName = fileFromRequest.Name;

        // some code

        return Ok();
    }

Where is the problem?

To create a Multipart request, I used tips from:

HttpClient StreamContent Adds File Name Twice

POST StreamContent with multiple files

Answer 1

, :

2 :

1.

:

await file.CopyToAsync(stream);

:

await file.CopyToAsync(stream);
stream.Position = 0;

, . , , , ( 0 ).

2. .

dotnetcoretutorials.com

---

:

:

    [HttpPost("UploadFiles")]
    public async Task<IActionResult> Post(IFormFile file)
    {
        var filePath = Path.GetTempFileName();
        using (var stream = new FileStream(filePath, FileMode.Create, FileAccess.ReadWrite))
        {
            await file.CopyToAsync(stream);
            stream.Position = 0;
            using (var formDataContent = new MultipartFormDataContent())
            {
                using (var httpClient = new HttpClient())
                {
                    formDataContent.Add(CreateFileContent(stream, "myfile.test", "application/octet-stream"));

                    var response = await httpClient.PostAsync(
                        "http://localhost:56595/home/upload",
                        formDataContent);
                    return Json(response);
                }
            }
        }
    }

    internal static StreamContent CreateFileContent(Stream stream, string fileName, string contentType)
    {
        var fileContent = new StreamContent(stream);
        fileContent.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("form-data")
        {
            Name = "\"file\"",
            FileName = "\"" + fileName + "\"",
        };
        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(contentType);
        return fileContent;
    }

:

:

            [HttpPost]
            [DisableFormValueModelBinding]
            public async Task<IActionResult> Upload()
            {
                var viewModel = new MyViewModel();
                try
                {
                    FormValueProvider formModel;
                    using (var stream = System.IO.File.Create("c:\\temp\\myfile.temp"))
                    {
                        formModel = await Request.StreamFile(stream);
                    }

                    var bindingSuccessful = await TryUpdateModelAsync(viewModel, prefix: "",
                        valueProvider: formModel);

                    if (!bindingSuccessful)
                    {
                        if (!ModelState.IsValid)
                        {
                            return BadRequest(ModelState);
                        }
                    }
                }
                catch(Exception exception)
                {
                    throw;
                }
                return Ok(viewModel);
            }

:

    public static class MultipartRequestHelper
{
    // Content-Type: multipart/form-data; boundary="----WebKitFormBoundarymx2fSWqWSd0OxQqq"
    // The spec says 70 characters is a reasonable limit.
    public static string GetBoundary(MediaTypeHeaderValue contentType, int lengthLimit)
    {
        var boundary = HeaderUtilities.RemoveQuotes(contentType.Boundary);
        if (string.IsNullOrWhiteSpace(boundary.ToString()))
        {
            throw new InvalidDataException("Missing content-type boundary.");
        }

        if (boundary.Length > lengthLimit)
        {
            throw new InvalidDataException(
                $"Multipart boundary length limit {lengthLimit} exceeded.");
        }

        return boundary.ToString();
    }

    public static bool IsMultipartContentType(string contentType)
    {
        return !string.IsNullOrEmpty(contentType)
               && contentType.IndexOf("multipart/", StringComparison.OrdinalIgnoreCase) >= 0;
    }

    public static bool HasFormDataContentDisposition(ContentDispositionHeaderValue contentDisposition)
    {
        // Content-Disposition: form-data; name="key";
        return contentDisposition != null
               && contentDisposition.DispositionType.Equals("form-data")
               && string.IsNullOrEmpty(contentDisposition.FileName.ToString())
               && string.IsNullOrEmpty(contentDisposition.FileNameStar.ToString());
    }

    public static bool HasFileContentDisposition(ContentDispositionHeaderValue contentDisposition)
    {
        // Content-Disposition: form-data; name="myfile1"; filename="Misc 002.jpg"
        return contentDisposition != null
               && contentDisposition.DispositionType.Equals("form-data")
               && (!string.IsNullOrEmpty(contentDisposition.FileName.ToString())
                   || !string.IsNullOrEmpty(contentDisposition.FileNameStar.ToString()));
    }
}

public static class FileStreamingHelper
{
    private static readonly FormOptions _defaultFormOptions = new FormOptions();

    public static async Task<FormValueProvider> StreamFile(this HttpRequest request, Stream targetStream)
    {
        if (!MultipartRequestHelper.IsMultipartContentType(request.ContentType))
        {
            throw new Exception($"Expected a multipart request, but got {request.ContentType}");
        }

        // Used to accumulate all the form url encoded key value pairs in the 
        // request.
        var formAccumulator = new KeyValueAccumulator();
        string targetFilePath = null;

        var boundary = MultipartRequestHelper.GetBoundary(
            MediaTypeHeaderValue.Parse(request.ContentType),
            _defaultFormOptions.MultipartBoundaryLengthLimit);
        var reader = new MultipartReader(boundary, request.Body);

        var section = await reader.ReadNextSectionAsync();
        while (section != null)
        {
            ContentDispositionHeaderValue contentDisposition;
            var hasContentDispositionHeader = ContentDispositionHeaderValue.TryParse(section.ContentDisposition, out contentDisposition);

            if (hasContentDispositionHeader)
            {
                if (MultipartRequestHelper.HasFileContentDisposition(contentDisposition))
                {
                    await section.Body.CopyToAsync(targetStream);
                }
                else if (MultipartRequestHelper.HasFormDataContentDisposition(contentDisposition))
                {
                    // Content-Disposition: form-data; name="key"
                    //
                    // value

                    // Do not limit the key name length here because the 
                    // multipart headers length limit is already in effect.
                    var key = HeaderUtilities.RemoveQuotes(contentDisposition.Name);
                    var encoding = GetEncoding(section);
                    using (var streamReader = new StreamReader(
                        section.Body,
                        encoding,
                        detectEncodingFromByteOrderMarks: true,
                        bufferSize: 1024,
                        leaveOpen: true))
                    {
                        // The value length limit is enforced by MultipartBodyLengthLimit
                        var value = await streamReader.ReadToEndAsync();
                        if (String.Equals(value, "undefined", StringComparison.OrdinalIgnoreCase))
                        {
                            value = String.Empty;
                        }
                        formAccumulator.Append(key.ToString(), value);

                        if (formAccumulator.ValueCount > _defaultFormOptions.ValueCountLimit)
                        {
                            throw new InvalidDataException($"Form key count limit {_defaultFormOptions.ValueCountLimit} exceeded.");
                        }
                    }
                }
            }

            // Drains any remaining section body that has not been consumed and
            // reads the headers for the next section.
            section = await reader.ReadNextSectionAsync();
        }

        // Bind form data to a model
        var formValueProvider = new FormValueProvider(
            BindingSource.Form,
            new FormCollection(formAccumulator.GetResults()),
            CultureInfo.CurrentCulture);

        return formValueProvider;
    }

    private static Encoding GetEncoding(MultipartSection section)
    {
        MediaTypeHeaderValue mediaType;
        var hasMediaTypeHeader = MediaTypeHeaderValue.TryParse(section.ContentType, out mediaType);
        // UTF-7 is insecure and should not be honored. UTF-8 will succeed in 
        // most cases.
        if (!hasMediaTypeHeader || Encoding.UTF7.Equals(mediaType.Encoding))
        {
            return Encoding.UTF8;
        }
        return mediaType.Encoding;
    }
}

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
public class DisableFormValueModelBindingAttribute : Attribute, IResourceFilter
{
    public void OnResourceExecuting(ResourceExecutingContext context)
    {
        var formValueProviderFactory = context.ValueProviderFactories
            .OfType<FormValueProviderFactory>()
            .FirstOrDefault();
        if (formValueProviderFactory != null)
        {
            context.ValueProviderFactories.Remove(formValueProviderFactory);
        }

        var jqueryFormValueProviderFactory = context.ValueProviderFactories
            .OfType<JQueryFormValueProviderFactory>()
            .FirstOrDefault();
        if (jqueryFormValueProviderFactory != null)
        {
            context.ValueProviderFactories.Remove(jqueryFormValueProviderFactory);
        }
    }

    public void OnResourceExecuted(ResourceExecutedContext context)
    {
    }
}

:

• ( ):

  fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(contentType);

.

• (on clientside) , MediaTypeHeaderValue :

  /-msdownload

  /JSON

  /-

• ( ) contentDisposition.FileNameStar , contentDisposition.FileNameStar.ToString()

• ( ) , serveride, (Mb), GB , .