import requests.auth

try:

# Python 3

from urllib.parse import urlparse

except ImportError:

# Python 2

from urlparse import urlparse

from .sign import HeaderSigner

class HTTPSignatureAuth(requests.auth.AuthBase):

"""

Sign a request using the http-signature scheme.

https://github.com/joyent/node-http-signature/blob/master/http_signing.md

`key_id` is the mandatory label indicating to the server which secret to

use secret is the filename of a pem file in the case of rsa, a password

string in the case of an hmac algorithm

`algorithm` is one of the six specified algorithms

headers is a list of http headers to be included in the signing string,

defaulting to "Date" alone.

"""

def __init__(self, key_id='', secret='', algorithm=None, sign_algorithm=None, headers=None):

headers = headers or []

self.header_signer = HeaderSigner(

key_id=key_id, secret=secret,

algorithm=algorithm, sign_algorithm=sign_algorithm, headers=headers)

self.uses_host = 'host' in [h.lower() for h in headers]

def __call__(self, r):

headers = self.header_signer.sign(

r.headers,

# 'Host' header unavailable in request object at this point

# if 'host' header is needed, extract it from the url

host=urlparse(r.url).netloc if self.uses_host else None,

method=r.method,

path=r.path_url)

r.headers.update(headers)

return r