diff options
Diffstat (limited to 'u1db/remote/http_client.py')
| -rw-r--r-- | u1db/remote/http_client.py | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/u1db/remote/http_client.py b/u1db/remote/http_client.py new file mode 100644 index 00000000..decddda3 --- /dev/null +++ b/u1db/remote/http_client.py @@ -0,0 +1,218 @@ +# 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 |