Support Chunked Transfer Encoding in Flask

wsgichunked.py

from flask import Flask

MAX_CONTENT_LENGTH = 16 * 1024 * 1024 

app = Flask(__name__)
app.config['MAX_CONTENT_LENGTH'] = MAX_CONTENT_LENGTH

class WSGITransferEncodingChunked:
    """Support HTTP Transfer-Encoding: chunked transfers"""
    def __init__(self, app):
        self.app = app


    def __call__(self, environ, start_response):
        from cStringIO import StringIO
        input = environ.get('wsgi.input')
        length = environ.get('CONTENT_LENGTH', '0')
        length = 0 if length == '' else int(length)
        body = ''
        if length == 0:
            if input is None:
                return
            if environ.get('HTTP_TRANSFER_ENCODING','0') == 'chunked':
                size = int(input.readline(),16)
                total_size = 0
                while size > 0:
                    # Validate max size to avoid DoS attacks
                    total_size += size
                    if total_size > MAX_CONTENT_LENGTH:
                        # Avoid DoS (using all available memory by streaming an infinite file)
                        start_response('413 Request Entity Too Large', [('Content-Type', 'text/plain')])
                        return []

                    body += input.read(size+2)
                    size = int(input.readline(),16)

        else:
            body = environ['wsgi.input'].read(length)

        environ["CONTENT_LENGTH"] = str(len(body))
        environ['wsgi.input'] = StringIO(body)

        return self.app(environ, start_response)


# Setup wsgi app
app.wsgi_app = WSGITransferEncodingChunked(app.wsgi_app)

Source http://stackoverflow.com/questions/14146824/flask-and-transfer-encoding-chunked/21342631#21342631