Add support for multipart/form-data

[flower-of-the-bridges]

Is your feature request related to a problem? Please describe

At the moment, body requests that are not of type application/json will be discarded by the policy.

Describe the solution you'd like

It would be nice if the parameters of a multipart/form-data requests will be parsed into the input object

Describe alternatives you've considered

Additional context

[fredmaggiowski]

Hi @flower-of-the-bridges multipart/form-data can contain both binary data and metadata associated with them; do you need the whole body or just the metadata?

[flower-of-the-bridges]

Hi @fredmaggiowski

Yes what I'd like is to extract some metadata (except for binary content) and make some policies with its value.

For example, If I make a request like this:

POST /my-multipart-endpoint 
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW

------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; my_metadata="my_metadata_value"
------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="file"; filename="myfile.txt"
Content-Type: <Content-Type header here>

(data)
------WebKitFormBoundary7MA4YWxkTrZu0gW--

I'd like to accomplish is to access the value my_metadata_value from a key my_metadata contained in the input.request.body object.

For example, a policy that will test whether the header is correct will be something like this:

package policies

check_form_metadata {
   input.request.body.metadata == "some_value"
}

[fredmaggiowski]

Yes what I'd like is to extract some metadata (except for binary content) and make some policies with its value.

OK thanks