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+      #
+      #
       # This program is free software; you can redistribute it and/or modify
       # it under the terms of the GNU General Public License as published by
       # the Free Software Foundation; either version 2 of the License, or
       # (at your option) any later version.
+      #
       # This program 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
       # General Public License for more details.
+      #
       # You should have received a copy of the GNU General Public License
       # along with this program; if not, write to the Free Software
       # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
       # 02110-1301, USA.
       """HTTP server module.
       """
       import BaseHTTPServer
       import cgi
       import logging
       import mimetools
       import OpenSSL
       import os
       import select
       import socket
       import sys
       import time
       import signal
       import logging
       import errno
       import threading
       from cStringIO import StringIO
       from ganeti import constants
       from ganeti import serializer
       from ganeti import workerpool
       from ganeti import utils
       HTTP_CLIENT_THREADS = 10
       HTTP_GANETI_VERSION = "Ganeti %s" % constants.RELEASE_VERSION
       WEEKDAYNAME = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']
       MONTHNAME = [None,
                    'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
                    'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
       # Default error message
       DEFAULT_ERROR_CONTENT_TYPE = "text/html"
       DEFAULT_ERROR_MESSAGE = """\
       <head>
       <title>Error response</title>
       </head>
       <body>
       <h1>Error response</h1>
       <p>Error code %(code)d.
       <p>Message: %(message)s.
       <p>Error code explanation: %(code)s = %(explain)s.
       </body>
       """
       HTTP_OK = 200
       HTTP_NO_CONTENT = 204
       HTTP_NOT_MODIFIED = 304
       HTTP_0_9 = "HTTP/0.9"
       HTTP_1_0 = "HTTP/1.0"
       HTTP_1_1 = "HTTP/1.1"
       HTTP_GET = "GET"
       HTTP_HEAD = "HEAD"
       HTTP_POST = "POST"
       HTTP_PUT = "PUT"
       HTTP_ETAG = "ETag"
       HTTP_HOST = "Host"
       HTTP_SERVER = "Server"
       HTTP_DATE = "Date"
       HTTP_USER_AGENT = "User-Agent"
       HTTP_CONTENT_TYPE = "Content-Type"
       HTTP_CONTENT_LENGTH = "Content-Length"
       HTTP_CONNECTION = "Connection"
       HTTP_KEEP_ALIVE = "Keep-Alive"
       _SSL_UNEXPECTED_EOF = "Unexpected EOF"
       class SocketClosed(socket.error):
         pass
       class _HttpClientError(Exception):
         """Internal exception for HTTP client errors.
         This should only be used for internal error reporting.
         """
         pass
       class HTTPException(Exception):
         code = None
         message = None
         def __init__(self, message=None):
           Exception.__init__(self)
           if message is not None:
             self.message = message
       class HTTPBadRequest(HTTPException):
         code = 400
       class HTTPForbidden(HTTPException):
         code = 403
       class HTTPNotFound(HTTPException):
         code = 404
       class HTTPGone(HTTPException):
         code = 410
       class HTTPLengthRequired(HTTPException):
         code = 411
       class HTTPInternalError(HTTPException):
         code = 500
       class HTTPNotImplemented(HTTPException):
         code = 501
       class HTTPServiceUnavailable(HTTPException):
         code = 503
       class HTTPVersionNotSupported(HTTPException):
         code = 505
       class ApacheLogfile:
         """Utility class to write HTTP server log files.
         The written format is the "Common Log Format" as defined by Apache:
         http://httpd.apache.org/docs/2.2/mod/mod_log_config.html#examples
         """
         def __init__(self, fd):
           """Constructor for ApacheLogfile class.
           Args:
           - fd: Open file object
           """
           self._fd = fd
         def LogRequest(self, request, format, *args):
           self._fd.write("%s %s %s [%s] %s\n" % (
             # Remote host address
             request.address_string(),
             # RFC1413 identity (identd)
             "-",
             # Remote user
             "-",
             # Request time
             self._FormatCurrentTime(),
             # Message
             format % args,
             ))
           self._fd.flush()
         def _FormatCurrentTime(self):
           """Formats current time in Common Log Format.
           """
           return self._FormatLogTime(time.time())
         def _FormatLogTime(self, seconds):
           """Formats time for Common Log Format.
           All timestamps are logged in the UTC timezone.
           Args:
           - seconds: Time in seconds since the epoch
           """
           (_, month, _, _, _, _, _, _, _) = tm = time.gmtime(seconds)
           format = "%d/" + MONTHNAME[month] + "/%Y:%H:%M:%S +0000"
           return time.strftime(format, tm)
       class HTTPJsonConverter:
         CONTENT_TYPE = "application/json"
         def Encode(self, data):
           return serializer.DumpJson(data)
         def Decode(self, data):
           return serializer.LoadJson(data)
       class _HttpSocketBase(object):
         """Base class for HTTP server and client.
         """
         def __init__(self):
           self._using_ssl = None
           self._ssl_cert = None
           self._ssl_key = None
         def _CreateSocket(self, ssl_key_path, ssl_cert_path, ssl_verify_peer):
           """Creates a TCP socket and initializes SSL if needed.
           @type ssl_key_path: string
           @param ssl_key_path: Path to file containing SSL key in PEM format
           @type ssl_cert_path: string
           @param ssl_cert_path: Path to file containing SSL certificate in PEM format
           @type ssl_verify_peer: bool
           @param ssl_verify_peer: Whether to require client certificate and compare
                                   it with our certificate
           """
           sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
           # Should we enable SSL?
           self._using_ssl = (ssl_cert_path and ssl_key_path)
           if not self._using_ssl:
             return sock
           ctx = OpenSSL.SSL.Context(OpenSSL.SSL.SSLv23_METHOD)
           ctx.set_options(OpenSSL.SSL.OP_NO_SSLv2)
           ssl_key_pem = utils.ReadFile(ssl_key_path)
           ssl_cert_pem = utils.ReadFile(ssl_cert_path)
           cr = OpenSSL.crypto
           self._ssl_cert = cr.load_certificate(cr.FILETYPE_PEM, ssl_cert_pem)
           self._ssl_key = cr.load_privatekey(cr.FILETYPE_PEM, ssl_key_pem)
           del cr
           ctx.use_privatekey(self._ssl_key)
           ctx.use_certificate(self._ssl_cert)
           ctx.check_privatekey()
           if ssl_verify_peer:
             ctx.set_verify(OpenSSL.SSL.VERIFY_PEER |
                            OpenSSL.SSL.VERIFY_FAIL_IF_NO_PEER_CERT,
                            self._SSLVerifyCallback)
           return OpenSSL.SSL.Connection(ctx, sock)
         def _SSLVerifyCallback(self, conn, cert, errnum, errdepth, ok):
           """Verify the certificate provided by the peer
           We only compare fingerprints. The client must use the same certificate as
           we do on our side.
           """
           assert self._ssl_cert and self._ssl_key, "SSL not initialized"
           return (self._ssl_cert.digest("sha1") == cert.digest("sha1") and
                   self._ssl_cert.digest("md5") == cert.digest("md5"))
       class _HttpConnectionHandler(object):
         """Implements server side of HTTP
         This class implements the server side of HTTP. It's based on code of Python's
         BaseHTTPServer, from both version 2.4 and 3k. It does not support non-ASCII
         character encodings. Keep-alive connections are not supported.
         """
         # The default request version.  This only affects responses up until
         # the point where the request line is parsed, so it mainly decides what
         # the client gets back when sending a malformed request line.
         # Most web servers default to HTTP 0.9, i.e. don't send a status line.
         default_request_version = HTTP_0_9
         # Error message settings
         error_message_format = DEFAULT_ERROR_MESSAGE
         error_content_type = DEFAULT_ERROR_CONTENT_TYPE
         responses = BaseHTTPServer.BaseHTTPRequestHandler.responses
         def __init__(self, server, conn, client_addr, fileio_class):
           """Initializes this class.
           Part of the initialization is reading the request and eventual POST/PUT
           data sent by the client.
           """
           self._server = server
           # We default rfile to buffered because otherwise it could be
           # really slow for large data (a getc() call per byte); we make
           # wfile unbuffered because (a) often after a write() we want to
           # read and we need to flush the line; (b) big writes to unbuffered
           # files are typically optimized by stdio even when big reads
           # aren't.
           self.rfile = fileio_class(conn, mode="rb", bufsize=-1)
           self.wfile = fileio_class(conn, mode="wb", bufsize=0)
           self.client_addr = client_addr
           self.request_headers = None
           self.request_method = None
           self.request_path = None
           self.request_requestline = None
           self.request_version = self.default_request_version
           self.response_body = None
           self.response_code = HTTP_OK
           self.response_content_type = None
           self.response_headers = {}
           self.should_fork = False
           try:
             self._ReadRequest()
             self._ReadPostData()
           except HTTPException, err:
             self._SetErrorStatus(err)
         def Close(self):
           if not self.wfile.closed:
             self.wfile.flush()
           self.wfile.close()
           self.rfile.close()
         def _DateTimeHeader(self):
           """Return the current date and time formatted for a message header.
           """
           (year, month, day, hh, mm, ss, wd, _, _) = time.gmtime()
           return ("%s, %02d %3s %4d %02d:%02d:%02d GMT" %
                   (WEEKDAYNAME[wd], day, MONTHNAME[month], year, hh, mm, ss))
         def _SetErrorStatus(self, err):
           """Sets the response code and body from a HTTPException.
           @type err: HTTPException
           @param err: Exception instance
           """
           try:
             (shortmsg, longmsg) = self.responses[err.code]
           except KeyError:
             shortmsg = longmsg = "Unknown"
           if err.message:
             message = err.message
           else:
             message = shortmsg
           values = {
             "code": err.code,
             "message": cgi.escape(message),
             "explain": longmsg,
+            }
           self.response_code = err.code
           self.response_content_type = self.error_content_type
           self.response_body = self.error_message_format % values
         def HandleRequest(self):
           """Handle the actual request.
           Calls the actual handler function and converts exceptions into HTTP errors.
           """
           # Don't do anything if there's already been a problem
           if self.response_code != HTTP_OK:
             return
           assert self.request_method, "Status code %s requires a method" % HTTP_OK
           # Check whether client is still there
           self.rfile.read(0)
           try:
             try:
               result = self._server.HandleRequest(self)
               # TODO: Content-type
               encoder = HTTPJsonConverter()
               body = encoder.Encode(result)
               self.response_content_type = encoder.CONTENT_TYPE
               self.response_body = body
             except (HTTPException, KeyboardInterrupt, SystemExit):
               raise
             except Exception, err:
               logging.exception("Caught exception")
               raise HTTPInternalError(message=str(err))
             except:
               logging.exception("Unknown exception")
               raise HTTPInternalError(message="Unknown error")
           except HTTPException, err:
             self._SetErrorStatus(err)
         def SendResponse(self):
           """Sends response to the client.
           """
           # Check whether client is still there
           self.rfile.read(0)
           logging.info("%s:%s %s %s", self.client_addr[0], self.client_addr[1],
                        self.request_requestline, self.response_code)
           if self.response_code in self.responses:
             response_message = self.responses[self.response_code][0]
           else:
             response_message = ""
           if self.request_version != HTTP_0_9:
             self.wfile.write("%s %d %s\r\n" %
                              (self.request_version, self.response_code,
                               response_message))
             self._SendHeader(HTTP_SERVER, HTTP_GANETI_VERSION)
             self._SendHeader(HTTP_DATE, self._DateTimeHeader())
             self._SendHeader(HTTP_CONTENT_TYPE, self.response_content_type)
             self._SendHeader(HTTP_CONTENT_LENGTH, str(len(self.response_body)))
             for key, val in self.response_headers.iteritems():
               self._SendHeader(key, val)
             # We don't support keep-alive at this time
             self._SendHeader(HTTP_CONNECTION, "close")
             self.wfile.write("\r\n")
           if (self.request_method != HTTP_HEAD and
               self.response_code >= HTTP_OK and
               self.response_code not in (HTTP_NO_CONTENT, HTTP_NOT_MODIFIED)):
             self.wfile.write(self.response_body)
         def _SendHeader(self, name, value):
           if self.request_version != HTTP_0_9:
             self.wfile.write("%s: %s\r\n" % (name, value))
         def _ReadRequest(self):
           """Reads and parses request line
           """
           raw_requestline = self.rfile.readline()
           requestline = raw_requestline
           if requestline[-2:] == '\r\n':
             requestline = requestline[:-2]
           elif requestline[-1:] == '\n':
             requestline = requestline[:-1]
           if not requestline:
             raise HTTPBadRequest("Empty request line")
           self.request_requestline = requestline
           logging.debug("HTTP request: %s", raw_requestline.rstrip("\r\n"))
           words = requestline.split()
           if len(words) == 3:
             [method, path, version] = words
             if version[:5] != 'HTTP/':
               raise HTTPBadRequest("Bad request version (%r)" % version)
             try:
               base_version_number = version.split('/', 1)[1]
               version_number = base_version_number.split(".")
               # RFC 2145 section 3.1 says there can be only one "." and
               #   - major and minor numbers MUST be treated as
               #      separate integers;
               #   - HTTP/2.4 is a lower version than HTTP/2.13, which in
               #      turn is lower than HTTP/12.3;
               #   - Leading zeros MUST be ignored by recipients.
               if len(version_number) != 2:
                 raise HTTPBadRequest("Bad request version (%r)" % version)
               version_number = int(version_number[0]), int(version_number[1])
             except (ValueError, IndexError):
               raise HTTPBadRequest("Bad request version (%r)" % version)
             if version_number >= (2, 0):
               raise HTTPVersionNotSupported("Invalid HTTP Version (%s)" %
                                             base_version_number)
           elif len(words) == 2:
             version = HTTP_0_9
             [method, path] = words
             if method != HTTP_GET:
               raise HTTPBadRequest("Bad HTTP/0.9 request type (%r)" % method)
           else:
             raise HTTPBadRequest("Bad request syntax (%r)" % requestline)
           # Examine the headers and look for a Connection directive
           headers = mimetools.Message(self.rfile, 0)
           self.request_method = method
           self.request_path = path
           self.request_version = version
           self.request_headers = headers
         def _ReadPostData(self):
           """Reads POST/PUT data
           Quoting RFC1945, section 7.2 (HTTP/1.0): "The presence of an entity body in
           a request is signaled by the inclusion of a Content-Length header field in
           the request message headers. HTTP/1.0 requests containing an entity body
           must include a valid Content-Length header field."
           """
           # While not according to specification, we only support an entity body for
           # POST and PUT.
           if (not self.request_method or
               self.request_method.upper() not in (HTTP_POST, HTTP_PUT)):
             self.request_post_data = None
             return
           content_length = None
           try:
             if HTTP_CONTENT_LENGTH in self.request_headers:
               content_length = int(self.request_headers[HTTP_CONTENT_LENGTH])
           except TypeError:
             pass
           except ValueError:
             pass
           # 411 Length Required is specified in RFC2616, section 10.4.12 (HTTP/1.1)
           if content_length is None:
             raise HTTPLengthRequired("Missing Content-Length header or"
                                      " invalid format")
           data = self.rfile.read(content_length)
           # TODO: Content-type, error handling
           if data:
             self.request_post_data = HTTPJsonConverter().Decode(data)
           else:
             self.request_post_data = None
           logging.debug("HTTP POST data: %s", self.request_post_data)
       class HttpServer(_HttpSocketBase):
         """Generic HTTP server class
         Users of this class must subclass it and override the HandleRequest function.
         """
         MAX_CHILDREN = 20
         def __init__(self, mainloop, local_address, port,
                      ssl_key_path=None, ssl_cert_path=None, ssl_verify_peer=False):
           """Initializes the HTTP server
           @type mainloop: ganeti.daemon.Mainloop
           @param mainloop: Mainloop used to poll for I/O events
           @type local_addess: string
           @param local_address: Local IP address to bind to
           @type port: int
           @param port: TCP port to listen on
           @type ssl_key_path: string
           @param ssl_key_path: Path to file containing SSL key in PEM format
           @type ssl_cert_path: string
           @param ssl_cert_path: Path to file containing SSL certificate in PEM format
           @type ssl_verify_peer: bool
           @param ssl_verify_peer: Whether to require client certificate and compare
                                   it with our certificate
           """
           _HttpSocketBase.__init__(self)
           self.mainloop = mainloop
           self.local_address = local_address
           self.port = port
           self.socket = self._CreateSocket(ssl_key_path, ssl_cert_path, ssl_verify_peer)
           # Allow port to be reused
           self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
           if self._using_ssl:
             self._fileio_class = _SSLFileObject
           else:
             self._fileio_class = socket._fileobject
           self._children = []
           mainloop.RegisterIO(self, self.socket.fileno(), select.POLLIN)
           mainloop.RegisterSignal(self)
         def Start(self):
           self.socket.bind((self.local_address, self.port))
           self.socket.listen(5)
         def Stop(self):
           self.socket.close()
         def OnIO(self, fd, condition):
           if condition & select.POLLIN:
             self._IncomingConnection()
         def OnSignal(self, signum):
           if signum == signal.SIGCHLD:
             self._CollectChildren(True)
         def _CollectChildren(self, quick):
           """Checks whether any child processes are done
           @type quick: bool
           @param quick: Whether to only use non-blocking functions
           """
           if not quick:
             # Don't wait for other processes if it should be a quick check
             while len(self._children) > self.MAX_CHILDREN:
               try:
                 # Waiting without a timeout brings us into a potential DoS situation.
                 # As soon as too many children run, we'll not respond to new
                 # requests. The real solution would be to add a timeout for children
                 # and killing them after some time.
                 pid, status = os.waitpid(0, 0)
               except os.error:
                 pid = None
               if pid and pid in self._children:
                 self._children.remove(pid)
           for child in self._children:
             try:
               pid, status = os.waitpid(child, os.WNOHANG)
             except os.error:
               pid = None
             if pid and pid in self._children:
               self._children.remove(pid)
         def _IncomingConnection(self):
           """Called for each incoming connection
           """
           (connection, client_addr) = self.socket.accept()
           self._CollectChildren(False)
           pid = os.fork()
           if pid == 0:
             # Child process
             logging.info("Connection from %s:%s", client_addr[0], client_addr[1])
             try:
               try:
                 try:
                   handler = None
                   try:
                     # Read, parse and handle request
                     handler = _HttpConnectionHandler(self, connection, client_addr,
                                                      self._fileio_class)
                     handler.HandleRequest()
                   finally:
                     # Try to send a response
                     if handler:
                       handler.SendResponse()
                       handler.Close()
                 except SocketClosed:
                   pass
               finally:
                 logging.info("Disconnected %s:%s", client_addr[0], client_addr[1])
             except:
               logging.exception("Error while handling request from %s:%s",
                                 client_addr[0], client_addr[1])
               os._exit(1)
             os._exit(0)
           else:
             self._children.append(pid)
         def HandleRequest(self, req):
           raise NotImplementedError()
       class HttpClientRequest(object):
         def __init__(self, host, port, method, path, headers=None, post_data=None,
                      ssl_key_path=None, ssl_cert_path=None, ssl_verify_peer=False):
           """Describes an HTTP request.
           @type host: string
           @param host: Hostname
           @type port: int
           @param port: Port
           @type method: string
           @param method: Method name
           @type path: string
           @param path: Request path
           @type headers: dict or None
           @param headers: Additional headers to send
           @type post_data: string or None
           @param post_data: Additional data to send
           """
           if post_data is not None:
             assert method.upper() in (HTTP_POST, HTTP_PUT), \
               "Only POST and GET requests support sending data"
           assert path.startswith("/"), "Path must start with slash (/)"
           self.host = host
           self.port = port
           self.ssl_key_path = ssl_key_path
           self.ssl_cert_path = ssl_cert_path
           self.ssl_verify_peer = ssl_verify_peer
           self.method = method
           self.path = path
           self.headers = headers
           self.post_data = post_data
           self.success = None
           self.error = None
           self.resp_status_line = None
           self.resp_version = None
           self.resp_status = None
           self.resp_reason = None
           self.resp_headers = None
           self.resp_body = None
       class HttpClientRequestExecutor(_HttpSocketBase):
         # Default headers
         DEFAULT_HEADERS = {
           HTTP_USER_AGENT: HTTP_GANETI_VERSION,
           # TODO: For keep-alive, don't send "Connection: close"
           HTTP_CONNECTION: "close",
+          }
         # Length limits
         STATUS_LINE_LENGTH_MAX = 512
         HEADER_LENGTH_MAX = 4 * 1024
         # Timeouts in seconds for socket layer
         # TODO: Make read timeout configurable per OpCode
         CONNECT_TIMEOUT = 5.0
         WRITE_TIMEOUT = 10
         READ_TIMEOUT = None
         CLOSE_TIMEOUT = 1
         # Parser state machine
         PS_STATUS_LINE = "status-line"
         PS_HEADERS = "headers"
         PS_BODY = "body"
         PS_COMPLETE = "complete"
         # Socket operations
         (OP_SEND,
          OP_RECV,
          OP_CLOSE_CHECK,
          OP_SHUTDOWN) = range(4)
         def __init__(self, req):
           """Initializes the HttpClientRequestExecutor class.
           @type req: HttpClientRequest
           @param req: Request object
           """
           _HttpSocketBase.__init__(self)
           self.request = req
           self.parser_status = self.PS_STATUS_LINE
           self.header_buffer = StringIO()
           self.body_buffer = StringIO()
           self.content_length = None
           self.server_will_close = None
           self.poller = select.poll()
           try:
             # TODO: Implement connection caching/keep-alive
             self.sock = self._CreateSocket(req.ssl_key_path,
                                            req.ssl_cert_path,
                                            req.ssl_verify_peer)
             # Disable Python's timeout
             self.sock.settimeout(None)
             # Operate in non-blocking mode
             self.sock.setblocking(0)
             force_close = True
             self._Connect()
             try:
               self._SendRequest()
               self._ReadResponse()
               # Only wait for server to close if we didn't have any exception.
               force_close = False
             finally:
               self._CloseConnection(force_close)
             self.sock.close()
             self.sock = None
             req.resp_body = self.body_buffer.getvalue()
             req.success = True
             req.error = None
           except _HttpClientError, err:
             req.success = False
             req.error = str(err)
         def _BuildRequest(self):
           """Build HTTP request.
           @rtype: string
           @return: Complete request
           """
           # Headers
           send_headers = self.DEFAULT_HEADERS.copy()
           if self.request.headers:
             send_headers.update(self.request.headers)
           send_headers[HTTP_HOST] = "%s:%s" % (self.request.host, self.request.port)
           if self.request.post_data:
             send_headers[HTTP_CONTENT_LENGTH] = len(self.request.post_data)
           buf = StringIO()
           # Add request line. We only support HTTP/1.0 (no chunked transfers and no
           # keep-alive).
           # TODO: For keep-alive, change to HTTP/1.1
           buf.write("%s %s %s\r\n" % (self.request.method.upper(),
                                       self.request.path, HTTP_1_0))
           # Add headers
           for name, value in send_headers.iteritems():
             buf.write("%s: %s\r\n" % (name, value))
           buf.write("\r\n")
           if self.request.post_data:
             buf.write(self.request.post_data)
           return buf.getvalue()
         def _ParseStatusLine(self):
           """Parses the status line sent by the server.
           """
           line = self.request.resp_status_line
           if not line:
             raise _HttpClientError("Empty status line")
           try:
             [version, status, reason] = line.split(None, 2)
           except ValueError:
             try:
               [version, status] = line.split(None, 1)
               reason = ""
             except ValueError:
               version = HTTP_9_0
           if version:
             version = version.upper()
           if version not in (HTTP_1_0, HTTP_1_1):
             # We do not support HTTP/0.9, despite the specification requiring it
             # (RFC2616, section 19.6)
             raise _HttpClientError("Only HTTP/1.0 and HTTP/1.1 are supported (%r)" %
                                    line)
           # The status code is a three-digit number
           try:
             status = int(status)
             if status < 100 or status > 999:
               status = -1
           except ValueError:
             status = -1
           if status == -1:
             raise _HttpClientError("Invalid status code (%r)" % line)
           self.request.resp_version = version
           self.request.resp_status = status
           self.request.resp_reason = reason
         def _WillServerCloseConnection(self):
           """Evaluate whether server will close the connection.
           @rtype: bool
           @return: Whether server will close the connection
           """
           hdr_connection = self.request.resp_headers.get(HTTP_CONNECTION, None)
           if hdr_connection:
             hdr_connection = hdr_connection.lower()
           # An HTTP/1.1 server is assumed to stay open unless explicitly closed.
           if self.request.resp_version == HTTP_1_1:
             return (hdr_connection and "close" in hdr_connection)
           # Some HTTP/1.0 implementations have support for persistent connections,
           # using rules different than HTTP/1.1.
           # For older HTTP, Keep-Alive indicates persistent connection.
           if self.request.resp_headers.get(HTTP_KEEP_ALIVE):
             return False
           # At least Akamai returns a "Connection: Keep-Alive" header, which was
           # supposed to be sent by the client.
           if hdr_connection and "keep-alive" in hdr_connection:
             return False
           return True
         def _ParseHeaders(self):
           """Parses the headers sent by the server.
           This function also adjusts internal variables based on the header values.
           """
           req = self.request
           # Parse headers
           self.header_buffer.seek(0, 0)
           req.resp_headers = mimetools.Message(self.header_buffer, 0)
           self.server_will_close = self._WillServerCloseConnection()
           # Do we have a Content-Length header?
           hdr_content_length = req.resp_headers.get(HTTP_CONTENT_LENGTH, None)
           if hdr_content_length:
             try:
               self.content_length = int(hdr_content_length)
             except ValueError:
               pass
             if self.content_length is not None and self.content_length < 0:
               self.content_length = None
           # does the body have a fixed length? (of zero)
           if (req.resp_status in (HTTP_NO_CONTENT, HTTP_NOT_MODIFIED) or
 <= req.resp_status < 200 or req.method == HTTP_HEAD):
             self.content_length = 0
           # if the connection remains open and a content-length was not provided,
           # then assume that the connection WILL close.
           if self.content_length is None:
             self.server_will_close = True
         def _CheckStatusLineLength(self, length):
           if length > self.STATUS_LINE_LENGTH_MAX:
             raise _HttpClientError("Status line longer than %d chars" %
                                    self.STATUS_LINE_LENGTH_MAX)
         def _CheckHeaderLength(self, length):
           if length > self.HEADER_LENGTH_MAX:
             raise _HttpClientError("Headers longer than %d chars" %
                                    self.HEADER_LENGTH_MAX)
         def _ParseBuffer(self, buf, eof):
           """Main function for HTTP response state machine.
           @type buf: string
           @param buf: Receive buffer
           @type eof: bool
           @param eof: Whether we've reached EOF on the socket
           @rtype: string
           @return: Updated receive buffer
           """
           if self.parser_status == self.PS_STATUS_LINE:
             # Expect status line
             idx = buf.find("\r\n")
             if idx >= 0:
               self.request.resp_status_line = buf[:idx]
               self._CheckStatusLineLength(len(self.request.resp_status_line))
               # Remove status line, including CRLF
               buf = buf[idx + 2:]
               self._ParseStatusLine()
               self.parser_status = self.PS_HEADERS
             else:
               # Check whether incoming data is getting too large, otherwise we just
               # fill our read buffer.
               self._CheckStatusLineLength(len(buf))
           if self.parser_status == self.PS_HEADERS:
             # Wait for header end
             idx = buf.find("\r\n\r\n")
             if idx >= 0:
               self.header_buffer.write(buf[:idx + 2])
               self._CheckHeaderLength(self.header_buffer.tell())
               # Remove headers, including CRLF
               buf = buf[idx + 4:]
               self._ParseHeaders()
               self.parser_status = self.PS_BODY
             else:
               # Check whether incoming data is getting too large, otherwise we just
               # fill our read buffer.
               self._CheckHeaderLength(len(buf))
           if self.parser_status == self.PS_BODY:
             self.body_buffer.write(buf)
             buf = ""
             # Check whether we've read everything
             if (eof or
                 (self.content_length is not None and
                  self.body_buffer.tell() >= self.content_length)):
               self.parser_status = self.PS_COMPLETE
           return buf
         def _WaitForCondition(self, event, timeout):
           """Waits for a condition to occur on the socket.
           @type event: int
           @param event: ORed condition (see select module)
           @type timeout: float or None
           @param timeout: Timeout in seconds
           @rtype: int or None
           @return: None for timeout, otherwise occured conditions
           """
           check = (event | select.POLLPRI |
                    select.POLLNVAL | select.POLLHUP | select.POLLERR)
           if timeout is not None:
             # Poller object expects milliseconds
             timeout *= 1000
           self.poller.register(self.sock, event)
           try:
             while True:
               # TODO: If the main thread receives a signal and we have no timeout, we
               # could wait forever. This should check a global "quit" flag or
               # something every so often.
               io_events = self.poller.poll(timeout)
               if io_events:
                 for (evfd, evcond) in io_events:
                   if evcond & check:
                     return evcond
               else:
                 # Timeout
                 return None
           finally:
             self.poller.unregister(self.sock)
         def _SocketOperation(self, op, arg1, error_msg, timeout_msg):
           """Wrapper around socket functions.
           This function abstracts error handling for socket operations, especially
           for the complicated interaction with OpenSSL.
           """
           if op == self.OP_SEND:
             event_poll = select.POLLOUT
             event_check = select.POLLOUT
             timeout = self.WRITE_TIMEOUT
           elif op in (self.OP_RECV, self.OP_CLOSE_CHECK):
             event_poll = select.POLLIN
             event_check = select.POLLIN | select.POLLPRI
             if op == self.OP_CLOSE_CHECK:
               timeout = self.CLOSE_TIMEOUT
             else:
               timeout = self.READ_TIMEOUT
           elif op == self.OP_SHUTDOWN:
             event_poll = None
             event_check = None
             # The timeout is only used when OpenSSL requests polling for a condition.
             # It is not advisable to have no timeout for shutdown.
             timeout = self.WRITE_TIMEOUT
           else:
             raise AssertionError("Invalid socket operation")
           # No override by default
           event_override = 0
           while True:
             # Poll only for certain operations and when asked for by an override
             if (event_override or
                 op in (self.OP_SEND, self.OP_RECV, self.OP_CLOSE_CHECK)):
               if event_override:
                 wait_for_event = event_override
               else:
                 wait_for_event = event_poll
               event = self._WaitForCondition(wait_for_event, timeout)
               if event is None:
                 raise _HttpClientTimeout(timeout_msg)
               if (op == self.OP_RECV and
                   event & (select.POLLNVAL | select.POLLHUP | select.POLLERR)):
                 return ""
               if not event & wait_for_event:
                 continue
             # Reset override
             event_override = 0
             try:
               try:
                 if op == self.OP_SEND:
                   return self.sock.send(arg1)
                 elif op in (self.OP_RECV, self.OP_CLOSE_CHECK):
                   return self.sock.recv(arg1)
                 elif op == self.OP_SHUTDOWN:
                   if self._using_ssl:
                     # PyOpenSSL's shutdown() doesn't take arguments
                     return self.sock.shutdown()
                   else:
                     return self.sock.shutdown(arg1)
               except OpenSSL.SSL.WantWriteError:
                 # OpenSSL wants to write, poll for POLLOUT
                 event_override = select.POLLOUT
                 continue
               except OpenSSL.SSL.WantReadError:
                 # OpenSSL wants to read, poll for POLLIN
                 event_override = select.POLLIN | select.POLLPRI
                 continue
               except OpenSSL.SSL.WantX509LookupError:
                 continue
               except OpenSSL.SSL.SysCallError, err:
                 if op == self.OP_SEND:
                   # arg1 is the data when writing
                   if err.args and err.args[0] == -1 and arg1 == "":
                     # errors when writing empty strings are expected
                     # and can be ignored
                     return 0
                 elif op == self.OP_RECV:
                   if err.args == (-1, _SSL_UNEXPECTED_EOF):
                     return ""
                 raise socket.error(err.args)
               except OpenSSL.SSL.Error, err:
                 raise socket.error(err.args)
             except socket.error, err:
               if err.args and err.args[0] == errno.EAGAIN:
                 # Ignore EAGAIN
                 continue
               raise _HttpClientError("%s: %s" % (error_msg, str(err)))
         def _Connect(self):
           """Non-blocking connect to host with timeout.
           """
           connected = False
           while True:
             try:
               connect_error = self.sock.connect_ex((self.request.host,
                                                     self.request.port))
             except socket.gaierror, err:
               raise _HttpClientError("Connection failed: %s" % str(err))
             if connect_error == errno.EINTR:
               # Mask signals
               pass
             elif connect_error == 0:
               # Connection established
               connected = True
               break
             elif connect_error == errno.EINPROGRESS:
               # Connection started
               break
             raise _HttpClientError("Connection failed (%s: %s)" %
                                    (connect_error, os.strerror(connect_error)))
           if not connected:
             # Wait for connection
             event = self._WaitForCondition(select.POLLOUT, self.CONNECT_TIMEOUT)
             if event is None:
               raise _HttpClientError("Timeout while connecting to server")
             # Get error code
             connect_error = self.sock.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
             if connect_error != 0:
               raise _HttpClientError("Connection failed (%s: %s)" %
                                      (connect_error, os.strerror(connect_error)))
           # Enable TCP keep-alive
           self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
           # If needed, Linux specific options are available to change the TCP
           # keep-alive settings, see "man 7 tcp" for TCP_KEEPCNT, TCP_KEEPIDLE and
           # TCP_KEEPINTVL.
         def _SendRequest(self):
           """Sends request to server.
           """
           buf = self._BuildRequest()
           while buf:
             # Send only 4 KB at a time
             data = buf[:4096]
             sent = self._SocketOperation(self.OP_SEND, data,
                                          "Error while sending request",
                                          "Timeout while sending request")
             # Remove sent bytes
             buf = buf[sent:]
           assert not buf, "Request wasn't sent completely"
         def _ReadResponse(self):
           """Read response from server.
           Calls the parser function after reading a chunk of data.
           """
           buf = ""
           eof = False
           while self.parser_status != self.PS_COMPLETE:
             data = self._SocketOperation(self.OP_RECV, 4096,
                                          "Error while reading response",
                                          "Timeout while reading response")
             if data:
               buf += data
             else:
               eof = True
             # Do some parsing and error checking while more data arrives
             buf = self._ParseBuffer(buf, eof)
             # Must be done only after the buffer has been evaluated
             if (eof and
                 self.parser_status in (self.PS_STATUS_LINE,
                                        self.PS_HEADERS)):
               raise _HttpClientError("Connection closed prematurely")
           # Parse rest
           buf = self._ParseBuffer(buf, True)
           assert self.parser_status == self.PS_COMPLETE
           assert not buf, "Parser didn't read full response"
         def _CloseConnection(self, force):
           """Closes the connection.
           """
           if self.server_will_close and not force:
             # Wait for server to close
             try:
               # Check whether it's actually closed
               if not self._SocketOperation(self.OP_CLOSE_CHECK, 1,
                                            "Error", "Timeout"):
                 return
             except (socket.error, _HttpClientError):
               # Ignore errors at this stage
               pass
           # Close the connection from our side
           self._SocketOperation(self.OP_SHUTDOWN, socket.SHUT_RDWR,
                                 "Error while shutting down connection",
                                 "Timeout while shutting down connection")
       class _HttpClientPendingRequest(object):
         """Data class for pending requests.
         """
         def __init__(self, request):
           self.request = request
           # Thread synchronization
           self.done = threading.Event()
       class HttpClientWorker(workerpool.BaseWorker):
         """HTTP client worker class.
         """
         def RunTask(self, pend_req):
           try:
             HttpClientRequestExecutor(pend_req.request)
           finally:
             pend_req.done.set()
       class HttpClientWorkerPool(workerpool.WorkerPool):
         def __init__(self, manager):
           workerpool.WorkerPool.__init__(self, HTTP_CLIENT_THREADS,
                                          HttpClientWorker)
           self.manager = manager
       class HttpClientManager(object):
         """Manages HTTP requests.
         """
         def __init__(self):
           self._wpool = HttpClientWorkerPool(self)
         def __del__(self):
           self.Shutdown()
         def ExecRequests(self, requests):
           """Execute HTTP requests.
           This function can be called from multiple threads at the same time.
           @type requests: List of HttpClientRequest instances
           @param requests: The requests to execute
           @rtype: List of HttpClientRequest instances
           @returns: The list of requests passed in
           """
           # _HttpClientPendingRequest is used for internal thread synchronization
           pending = [_HttpClientPendingRequest(req) for req in requests]
           try:
             # Add requests to queue
             for pend_req in pending:
               self._wpool.AddTask(pend_req)
           finally:
             # In case of an exception we should still wait for the rest, otherwise
             # another thread from the worker pool could modify the request object
             # after we returned.
             # And wait for them to finish
             for pend_req in pending:
               pend_req.done.wait()
           # Return original list
           return requests
         def Shutdown(self):
           self._wpool.Quiesce()
           self._wpool.TerminateWorkers()
       class _SSLFileObject(object):
         """Wrapper around socket._fileobject
         This wrapper is required to handle OpenSSL exceptions.
         """
         def _RequireOpenSocket(fn):
           def wrapper(self, *args, **kwargs):
             if self.closed:
               raise SocketClosed("Socket is closed")
             return fn(self, *args, **kwargs)
           return wrapper
         def __init__(self, sock, mode='rb', bufsize=-1):
           self._base = socket._fileobject(sock, mode=mode, bufsize=bufsize)
         def _ConnectionLost(self):
           self._base = None
         def _getclosed(self):
           return self._base is None or self._base.closed
         closed = property(_getclosed, doc="True if the file is closed")
         @_RequireOpenSocket
         def close(self):
           return self._base.close()
         @_RequireOpenSocket
         def flush(self):
           return self._base.flush()
         @_RequireOpenSocket
         def fileno(self):
           return self._base.fileno()
         @_RequireOpenSocket
         def read(self, size=-1):
           return self._ReadWrapper(self._base.read, size=size)
         @_RequireOpenSocket
         def readline(self, size=-1):
           return self._ReadWrapper(self._base.readline, size=size)
         def _ReadWrapper(self, fn, *args, **kwargs):
           while True:
             try:
               return fn(*args, **kwargs)
             except OpenSSL.SSL.ZeroReturnError, err:
               self._ConnectionLost()
               return ""
             except OpenSSL.SSL.WantReadError:
               continue
             #except OpenSSL.SSL.WantWriteError:
             # TODO
             except OpenSSL.SSL.SysCallError, (retval, desc):
               if ((retval == -1 and desc == _SSL_UNEXPECTED_EOF)
                   or retval > 0):
                 self._ConnectionLost()
                 return ""
               logging.exception("Error in OpenSSL")
               self._ConnectionLost()
               raise socket.error(err.args)
             except OpenSSL.SSL.Error, err:
               self._ConnectionLost()
               raise socket.error(err.args)
         @_RequireOpenSocket
         def write(self, data):
           return self._WriteWrapper(self._base.write, data)
         def _WriteWrapper(self, fn, *args, **kwargs):
           while True:
             try:
               return fn(*args, **kwargs)
             except OpenSSL.SSL.ZeroReturnError, err:
               self._ConnectionLost()
               return 0
             except OpenSSL.SSL.WantWriteError:
               continue
             #except OpenSSL.SSL.WantReadError:
             # TODO
             except OpenSSL.SSL.SysCallError, err:
               if err.args[0] == -1 and data == "":
                 # errors when writing empty strings are expected
                 # and can be ignored
                 return 0
               self._ConnectionLost()
               raise socket.error(err.args)
             except OpenSSL.SSL.Error, err:
               self._ConnectionLost()
               raise socket.error(err.args)

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