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# Copyright (c) 2009-2011, Eucalyptus Systems, Inc.
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# without modification, are permitted provided that the following conditions
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#   following disclaimer.
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# Author: Mitch Garnaat mgarnaat@eucalyptus.com

import urllib, base64
import time
import boto.auth_handler
from boto.exception import BotoClientError
from hashlib import sha1 as sha
import hmac
from M2Crypto import RSA
        
class EucaNCAuthHandler(boto.auth_handler.AuthHandler):
    """Provides Eucalyptus NC Authentication."""

    capability = ['euca-nc']

    def __init__(self, host, config, provider):
        boto.auth_handler.AuthHandler.__init__(self, host, config, provider)
        self.hmac = hmac.new(provider.secret_key, digestmod=sha)
        self.private_key_path = None
        
    def _calc_signature(self, params, headers, verb, path):
        boto.log.debug('using euca_signature')
        string_to_sign = '%s\n%s\n%s\n' % (verb, headers['Date'], path)
        keys = params.keys()
        keys.sort()
        pairs = []
        for key in keys:
            val = params[key]
            pairs.append(urllib.quote(key, safe='') + '=' + urllib.quote(val, safe='-_~'))
        qs = '&'.join(pairs)
        boto.log.debug('query string: %s' % qs)
        string_to_sign += qs
        hmac = self.hmac.copy()
        hmac.update(string_to_sign)
        sha_manifest = sha()
        sha_manifest.update(string_to_sign)
        private_key = RSA.load_key(self.private_key_path)
        signature_value = private_key.sign(sha_manifest.digest())
        b64 = base64.b64encode(signature_value)
        boto.log.debug('len(b64)=%d' % len(b64))
        boto.log.debug('base64 encoded digest: %s' % b64)
        return (qs, b64)

    def add_auth(self, http_request, **kwargs):
        headers = http_request.headers
        params = http_request.params
        qs, signature = self._calc_signature(http_request.params,
                                             http_request.headers,
                                             http_request.method,
                                             http_request.path)
        headers['EucaSignature'] = signature
        boto.log.debug('query_string: %s Signature: %s' % (qs, signature))
        if http_request.method == 'POST':
            headers['Content-Type'] = 'application/x-www-form-urlencoded; charset=UTF-8'
            http_request.body = qs
        else:
            http_request.body = ''