broken auth on payloads containing tilde chars

[shahin]

client.py uses urllib.urlencode, which percent-encodes the tilde character (~) as %7E in order to generate the signature. ~ isn't really a reserved character, so this isn't guaranteed consistent with other URI libraries.

On the other hand, the base_url is encoded via requests in which the tilde issue has been corrected and no longer matches urllib's weird behavior.

Ultimately this results in a 403 error (client id omitted below):

"Unable to authenticate the request. Provided 'signature' is not valid for the provided client ID, or the provided 'client' is not valid.
The signature was checked against the URL: /maps/api/geocode/json?address=560+Maple+Street+South+%2310~&components=administrative_area%3AMN%7Clocality%3AWaconia%7Cpostal_code%3A55387&client=
If this does not match the URL you requested, please ensure that your request is URL encoded correctly. Learn more: https://developers.google.com/maps/documentation/business/webservices/auth"

Although tildes should be rare, ideal behavior would probably be either:

1. Use the same encoding library for the base_url and for computing the authed_url, or
2. Raise an informative exception on disallowed characters (incl. tilde)

instead of waiting for a non-specific 403.

[stephenmcd]

Thanks a lot for the detailed report! I've a fix incoming.