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# Copyright 2011-2012 Canonical Ltd.
#
# This file is part of u1db.
#
# u1db is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3
# as published by the Free Software Foundation.
#
# u1db is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with u1db. If not, see <http://www.gnu.org/licenses/>.
"""Base class to make requests to a remote HTTP server."""
import httplib
from oauth import oauth
try:
import simplejson as json
except ImportError:
import json # noqa
import socket
import ssl
import sys
import urlparse
import urllib
from time import sleep
from u1db import (
errors,
)
from u1db.remote import (
http_errors,
)
from u1db.remote.ssl_match_hostname import ( # noqa
CertificateError,
match_hostname,
)
# Ubuntu/debian
# XXX other...
CA_CERTS = "/etc/ssl/certs/ca-certificates.crt"
def _encode_query_parameter(value):
"""Encode query parameter."""
if isinstance(value, bool):
if value:
value = 'true'
else:
value = 'false'
return unicode(value).encode('utf-8')
class _VerifiedHTTPSConnection(httplib.HTTPSConnection):
"""HTTPSConnection verifying server side certificates."""
# derived from httplib.py
def connect(self):
"Connect to a host on a given (SSL) port."
sock = socket.create_connection((self.host, self.port),
self.timeout, self.source_address)
if self._tunnel_host:
self.sock = sock
self._tunnel()
if sys.platform.startswith('linux'):
cert_opts = {
'cert_reqs': ssl.CERT_REQUIRED,
'ca_certs': CA_CERTS
}
else:
# XXX no cert verification implemented elsewhere for now
cert_opts = {}
self.sock = ssl.wrap_socket(sock, self.key_file, self.cert_file,
ssl_version=ssl.PROTOCOL_SSLv3,
**cert_opts
)
if cert_opts:
match_hostname(self.sock.getpeercert(), self.host)
class HTTPClientBase(object):
"""Base class to make requests to a remote HTTP server."""
# by default use HMAC-SHA1 OAuth signature method to not disclose
# tokens
# NB: given that the content bodies are not covered by the
# signatures though, to achieve security (against man-in-the-middle
# attacks for example) one would need HTTPS
oauth_signature_method = oauth.OAuthSignatureMethod_HMAC_SHA1()
# Will use these delays to retry on 503 befor finally giving up. The final
# 0 is there to not wait after the final try fails.
_delays = (1, 1, 2, 4, 0)
def __init__(self, url, creds=None):
self._url = urlparse.urlsplit(url)
self._conn = None
self._creds = {}
if creds is not None:
if len(creds) != 1:
raise errors.UnknownAuthMethod()
auth_meth, credentials = creds.items()[0]
try:
set_creds = getattr(self, 'set_%s_credentials' % auth_meth)
except AttributeError:
raise errors.UnknownAuthMethod(auth_meth)
set_creds(**credentials)
def set_oauth_credentials(self, consumer_key, consumer_secret,
token_key, token_secret):
self._creds = {'oauth': (
oauth.OAuthConsumer(consumer_key, consumer_secret),
oauth.OAuthToken(token_key, token_secret))}
def _ensure_connection(self):
if self._conn is not None:
return
if self._url.scheme == 'https':
connClass = _VerifiedHTTPSConnection
else:
connClass = httplib.HTTPConnection
self._conn = connClass(self._url.hostname, self._url.port)
def close(self):
if self._conn:
self._conn.close()
self._conn = None
# xxx retry mechanism?
def _error(self, respdic):
descr = respdic.get("error")
exc_cls = errors.wire_description_to_exc.get(descr)
if exc_cls is not None:
message = respdic.get("message")
raise exc_cls(message)
def _response(self):
resp = self._conn.getresponse()
body = resp.read()
headers = dict(resp.getheaders())
if resp.status in (200, 201):
return body, headers
elif resp.status in http_errors.ERROR_STATUSES:
try:
respdic = json.loads(body)
except ValueError:
pass
else:
self._error(respdic)
# special case
if resp.status == 503:
raise errors.Unavailable(body, headers)
raise errors.HTTPError(resp.status, body, headers)
def _sign_request(self, method, url_query, params):
if 'oauth' in self._creds:
consumer, token = self._creds['oauth']
full_url = "%s://%s%s" % (self._url.scheme, self._url.netloc,
url_query)
oauth_req = oauth.OAuthRequest.from_consumer_and_token(
consumer, token,
http_method=method,
parameters=params,
http_url=full_url
)
oauth_req.sign_request(
self.oauth_signature_method, consumer, token)
# Authorization: OAuth ...
return oauth_req.to_header().items()
else:
return []
def _request(self, method, url_parts, params=None, body=None,
content_type=None):
self._ensure_connection()
unquoted_url = url_query = self._url.path
if url_parts:
if not url_query.endswith('/'):
url_query += '/'
unquoted_url = url_query
url_query += '/'.join(urllib.quote(part, safe='')
for part in url_parts)
# oauth performs its own quoting
unquoted_url += '/'.join(url_parts)
encoded_params = {}
if params:
for key, value in params.items():
key = unicode(key).encode('utf-8')
encoded_params[key] = _encode_query_parameter(value)
url_query += ('?' + urllib.urlencode(encoded_params))
if body is not None and not isinstance(body, basestring):
body = json.dumps(body)
content_type = 'application/json'
headers = {}
if content_type:
headers['content-type'] = content_type
headers.update(
self._sign_request(method, unquoted_url, encoded_params))
for delay in self._delays:
try:
self._conn.request(method, url_query, body, headers)
return self._response()
except errors.Unavailable, e:
sleep(delay)
raise e
def _request_json(self, method, url_parts, params=None, body=None,
content_type=None):
res, headers = self._request(method, url_parts, params, body,
content_type)
return json.loads(res), headers
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