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#============================================================================
# This library is free software; you can redistribute it and/or
# modify it under the terms of version 2.1 of the GNU Lesser General Public
# License as published by the Free Software Foundation.
#
# This library 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 this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#============================================================================
# Copyright (C) 2004, 2005 Mike Wray <mike.wray@hp.com>
# Copyright (C) 2005 XenSource Ltd.
#============================================================================
import socket
import httplib
import time
import types
from encode import *
import sxp
from xen.xend import XendRoot
DEBUG = 0
HTTP_OK = 200
HTTP_CREATED = 201
HTTP_ACCEPTED = 202
HTTP_NO_CONTENT = 204
xroot = XendRoot.instance()
class XendError(RuntimeError):
"""Error class for 'expected errors' when talking to xend.
"""
pass
class XendRequest:
"""A request to xend.
"""
def __init__(self, url, method, args):
"""Create a request. Sets up the headers, argument data, and the
url.
@param url: the url to request
@param method: request method, GET or POST
@param args: dict containing request args, if any
"""
if url.proto != 'http':
raise ValueError('Invalid protocol: ' + url.proto)
(hdr, data) = encode_data(args)
if args and method == 'GET':
url.query = data
data = None
if method == "POST" and url.path.endswith('/'):
url.path = url.path[:-1]
self.headers = hdr
self.data = data
self.url = url
self.method = method
class XendClientProtocol:
"""Abstract class for xend clients.
"""
def xendRequest(self, url, method, args=None):
"""Make a request to xend.
Implement in a subclass.
@param url: xend request url
@param method: http method: POST or GET
@param args: request arguments (dict)
"""
raise NotImplementedError()
def xendGet(self, url, args=None):
"""Make a xend request using HTTP GET.
Requests using GET are usually 'safe' and may be repeated without
nasty side-effects.
@param url: xend request url
@param data: request arguments (dict)
"""
return self.xendRequest(url, "GET", args)
def xendPost(self, url, args):
"""Make a xend request using HTTP POST.
Requests using POST potentially cause side-effects, and should
not be repeated unless you really want to repeat the side
effect.
@param url: xend request url
@param args: request arguments (dict)
"""
return self.xendRequest(url, "POST", args)
def handleStatus(self, _, status, message):
"""Handle the status returned from the request.
"""
status = int(status)
if status in [ HTTP_NO_CONTENT ]:
return None
if status not in [ HTTP_OK, HTTP_CREATED, HTTP_ACCEPTED ]:
return self.handleException(XendError(message))
return 'ok'
def handleResponse(self, data):
"""Handle the data returned in response to the request.
"""
if data is None: return None
typ = self.getHeader('Content-Type')
if typ != sxp.mime_type:
return data
try:
pin = sxp.Parser()
pin.input(data);
pin.input_eof()
val = pin.get_val()
except sxp.ParseError, err:
return self.handleException(err)
if isinstance(val, types.ListType) and sxp.name(val) == 'xend.err':
err = XendError(val[1])
return self.handleException(err)
return val
def handleException(self, err):
"""Handle an exception during the request.
May be overridden in a subclass.
"""
raise err
def getHeader(self, key):
"""Get a header from the response.
Case is ignored in the key.
@param key: header key
@return: header
"""
raise NotImplementedError()
class HttpXendClientProtocol(XendClientProtocol):
"""A synchronous xend client. This will make a request, wait for
the reply and return the result.
"""
resp = None
request = None
def makeConnection(self, url):
return httplib.HTTPConnection(url.location())
def makeRequest(self, url, method, args):
return XendRequest(url, method, args)
def xendRequest(self, url, method, args=None):
"""Make a request to xend.
@param url: xend request url
@param method: http method: POST or GET
@param args: request arguments (dict)
"""
retries = 0
while retries < 2:
self.request = self.makeRequest(url, method, args)
conn = self.makeConnection(url)
try:
if DEBUG: conn.set_debuglevel(1)
conn.request(method, url.fullpath(), self.request.data,
self.request.headers)
try:
resp = conn.getresponse()
self.resp = resp
val = self.handleStatus(resp.version, resp.status,
resp.reason)
if val is None:
data = None
else:
data = resp.read()
val = self.handleResponse(data)
return val
except httplib.BadStatusLine:
retries += 1
time.sleep(5)
finally:
conn.close()
raise XendError("Received invalid response from Xend, twice.")
def getHeader(self, key):
return self.resp.getheader(key)
class UnixConnection(httplib.HTTPConnection):
"""Subclass of Python library HTTPConnection that uses a unix-domain socket.
"""
def __init__(self, path):
httplib.HTTPConnection.__init__(self, 'localhost')
self.path = path
def connect(self):
sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
sock.connect(self.path)
self.sock = sock
class UnixXendClientProtocol(HttpXendClientProtocol):
"""A synchronous xend client using a unix-domain socket.
"""
def __init__(self, path=None):
if path is None:
path = xroot.get_xend_unix_path()
self.path = path
def makeConnection(self, _):
return UnixConnection(self.path)
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