ltbam/Http-Multipart-Data-Parser

A C# Http Multipart/form-data parser that works correctly on binary data and very large files.

What is it?

The Http Multipart Parser does it exactly what it claims on the tin: parses multipart/form-data. This particular parser is well suited to parsing large data from streams as it doesn't attempt to read the entire stream at once and procudes a set of streams for file data.

Installation

Simply add the HttpMultipartParser project to your solution and reference it in the projects you want to use it in.

There is also a NuGet package provided.

Dependencies

The parser was built and tested for NET 4.0. Versions lower then this may work but are untested.

How do I use it?

Non-Streaming (Simple, don't use on very large files)

1. Create a new MultipartFormDataParser with the stream containing the multipart/form-data.
2. Access the data through the parser.

Streaming (Handles large files)

1. Create a new StreamingMultipartFormDataParser with the stream containing the multipart/form-data
2. Set up the ParameterHandler and FileHandler delegates
3. Call parser.Run()
4. The delegates will be called as data streams in.

Examples

Single file

// stream:
-----------------------------41952539122868
Content-Disposition: form-data; name="username"

example
-----------------------------41952539122868
Content-Disposition: form-data; name="email"

example@data.com
-----------------------------41952539122868
Content-Disposition: form-data; name="files[]"; filename="photo1.jpg"
Content-Type: image/jpeg

ExampleBinaryData012031203
-----------------------------41952539122868--

// ===== Simple Parsing ====
// parse:
var parser = new MultipartFormDataParser(stream);

// From this point the data is parsed, we can retrieve the
// form data using the GetParameterValue method.
var username = parser.GetParameterValue("username");
var email = parser.GetParameterValue("email")

// Files are stored in a list:
var file = parser.Files.First();
string filename = file.FileName;
Stream data = file.Data;

// ==== Advanced Parsing ====
// parse:
var parser = new StreamingMultipartFormDataParser(stream);
parser.ParameterHandler += parameter => DoSomethingWithParameter(parameter);
parser.FileHandler += (name, fileName, type, disposition, buffer, bytes) =>
{
    // Write the part of the file we've recieved to a file stream. (Or do something else)
    filestream.Write(buffer, 0, bytes);
}

Multiple Parameters

// stream:
-----------------------------41952539122868
Content-Disposition: form-data; name="checkbox"

likes_cake
-----------------------------41952539122868
Content-Disposition: form-data; name="checkbox"

likes_cookies
-----------------------------41952539122868--

// ===== Simple Parsing ====
// parse:
var parser = new MultipartFormDataParser(stream);

// From this point the data is parsed, we can retrieve the
// form data from the GetParameterValues method
var checkboxResponses = parser.GetParameterValues("checkbox");
foreach(var parameter in checkboxResponses)
{
    Console.WriteLine("Parameter {0} is {1}", parameter.Name, parameter.Data)
}

Multiple Files

// stream:
-----------------------------41111539122868
Content-Disposition: form-data; name="files[]"; filename="photo1.jpg"
Content-Type: image/jpeg

MoreBinaryData
-----------------------------41111539122868
Content-Disposition: form-data; name="files[]"; filename="photo2.jpg"
Content-Type: image/jpeg

ImagineLotsOfBinaryData
-----------------------------41111539122868--

// ===== Simple Parsing ====
// parse:
var parser = new MultipartFormDataParser(stream);

// Loop through all the files
foreach(var file in parser.Files)
{
    Stream data = file.Data;

    // Do stuff with the data.
}

// ==== Advanced Parsing ====
// parse:
var parser = new StreamingMultipartFormDataParser(stream);
parser.ParameterHandler += parameter => DoSomethingWithParameter(parameter);
parser.FileHandler += (name, fileName, type, disposition, buffer, bytes) =>
{
    // Write the part of the file we've recieved to a file stream. (Or do something else)
    // Assume that filesreamsByName is a Dictionary<string, FileStream> of all the files
    // we are writing.
    filestreamsByName[name].Write(buffer, 0, bytes);
}

Licensing

Please see LICENSE