Support FormPost for uploading directly from the browser

[robert-bor]

Introduction

It is possible to upload a file directly from the browser to the ObjectStore using FormPost. This is the code in the HTML:

<form action="https://0fef7424e0f44779abf6e98d0bae9874.objectstore.eu/installables" method="POST"
        enctype="multipart/form-data">
    <input type="hidden" name="redirect" value="https://sis.42.nl/list" />
    <input type="hidden" name="max_file_size" value="104857600" />
    <input type="hidden" name="max_file_count" value="10" />
    <input type="hidden" name="expires" value="1375255337" />
    <input type="hidden" name="signature" value="c264da6ff7910a6a161e2da4b546c3aeee1a3d9a" />
    <input type="file" name="file1" /><br />
    <input type="submit" />
</form>

Technical background

JOSS must be capable of generating the signature for FormPost on the basis of the following parameters:

• path (same mechanism as TempURL)
• redirect
• max_file_size
• max_file_count
• expires (same mechanism as TempURL)

I got it working in a test setup with this configuration:

path: /v1/AUTH_0fef7424e0f44779abf6e98d0bae9874/installables
redirect: https://sis.42.nl/list
max_file_size: 104857600
max_file_count: 10
expires: 1375255337
signature: c264da6ff7910a6a161e2da4b546c3aeee1a3d9a

This python code helps in determining the signature:

import hmac
from hashlib import sha1
from time import time
print '============'
path = '/v1/AUTH_0fef7424e0f44779abf6e98d0bae9874/installables'
print 'path: '+path
redirect = 'https://sis.42.nl/list'
print 'redirect: '+redirect
max_file_size = 104857600
print 'max_file_size: '+str(max_file_size)
max_file_count = 10
print 'max_file_count: '+str(max_file_count)
expires = int(time() + 86400)
print 'expires: '+str(expires)
key = '********'
hmac_body = '%s\n%s\n%s\n%s\n%s' % (path, redirect,
    max_file_size, max_file_count, expires)
signature = hmac.new(key, hmac_body, sha1).hexdigest()
print 'signature: '+signature

Note that the official documentation places a '/' at the end of path. This doesn't work.

Reading

• http://docs.openstack.org/developer/swift/misc.html#module-swift.common.middleware.formpost
• more information on Temp URL (path and expires): Support TempURL for content in private containers #32