/lib/http/server.py - snf-ganeti - Greek Research and Technology Network's projects

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+      #
+      #
       # Copyright (C) 2007, 2008 Google Inc.
+      #
       # 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 os
       import socket
       import time
       import signal
       import asyncore
       from ganeti import http
       from ganeti import utils
       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 = """\
       <html>
       <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>
       </html>
       """
       def _DateTimeHeader(gmnow=None):
         """Return the current date and time formatted for a message header.
         The time MUST be in the GMT timezone.
         """
         if gmnow is None:
           gmnow = time.gmtime()
         (year, month, day, hh, mm, ss, wd, _, _) = gmnow
         return ("%s, %02d %3s %4d %02d:%02d:%02d GMT" %
                 (WEEKDAYNAME[wd], day, MONTHNAME[month], year, hh, mm, ss))
       class _HttpServerRequest(object):
         """Data structure for HTTP request on server side.
         """
         def __init__(self, method, path, headers, body):
           # Request attributes
           self.request_method = method
           self.request_path = path
           self.request_headers = headers
           self.request_body = body
           # Response attributes
           self.resp_headers = {}
           # Private data for request handler (useful in combination with
           # authentication)
           self.private = None
         def __repr__(self):
           status = ["%s.%s" % (self.__class__.__module__, self.__class__.__name__),
                     self.request_method, self.request_path,
                     "headers=%r" % str(self.request_headers),
                     "body=%r" % (self.request_body, )]
           return "<%s at %#x>" % (" ".join(status), id(self))
       class _HttpServerToClientMessageWriter(http.HttpMessageWriter):
         """Writes an HTTP response to client.
         """
         def __init__(self, sock, request_msg, response_msg, write_timeout):
           """Writes the response to the client.
           @type sock: socket
           @param sock: Target socket
           @type request_msg: http.HttpMessage
           @param request_msg: Request message, required to determine whether
               response may have a message body
           @type response_msg: http.HttpMessage
           @param response_msg: Response message
           @type write_timeout: float
           @param write_timeout: Write timeout for socket
           """
           self._request_msg = request_msg
           self._response_msg = response_msg
           http.HttpMessageWriter.__init__(self, sock, response_msg, write_timeout)
         def HasMessageBody(self):
           """Logic to detect whether response should contain a message body.
           """
           if self._request_msg.start_line:
             request_method = self._request_msg.start_line.method
           else:
             request_method = None
           response_code = self._response_msg.start_line.code
           # RFC2616, section 4.3: "A message-body MUST NOT be included in a request
           # if the specification of the request method (section 5.1.1) does not allow
           # sending an entity-body in requests"
+          #
           # RFC2616, section 9.4: "The HEAD method is identical to GET except that
           # the server MUST NOT return a message-body in the response."
+          #
           # RFC2616, section 10.2.5: "The 204 response MUST NOT include a
           # message-body [...]"
+          #
           # RFC2616, section 10.3.5: "The 304 response MUST NOT contain a
           # message-body, [...]"
           return (http.HttpMessageWriter.HasMessageBody(self) and
                   (request_method is not None and
                    request_method != http.HTTP_HEAD) and
                   response_code >= http.HTTP_OK and
                   response_code not in (http.HTTP_NO_CONTENT,
                                         http.HTTP_NOT_MODIFIED))
       class _HttpClientToServerMessageReader(http.HttpMessageReader):
         """Reads an HTTP request sent by client.
         """
         # Length limits
         START_LINE_LENGTH_MAX = 4096
         HEADER_LENGTH_MAX = 4096
         def ParseStartLine(self, start_line):
           """Parses the start line sent by client.
           Example: "GET /index.html HTTP/1.1"
           @type start_line: string
           @param start_line: Start line
           """
           # Empty lines are skipped when reading
           assert start_line
           logging.debug("HTTP request: %s", start_line)
           words = start_line.split()
           if len(words) == 3:
             [method, path, version] = words
             if version[:5] != 'HTTP/':
               raise http.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 http.HttpBadRequest("Bad request version (%r)" % version)
               version_number = (int(version_number[0]), int(version_number[1]))
             except (ValueError, IndexError):
               raise http.HttpBadRequest("Bad request version (%r)" % version)
             if version_number >= (2, 0):
               raise http.HttpVersionNotSupported("Invalid HTTP Version (%s)" %
                                             base_version_number)
           elif len(words) == 2:
             version = http.HTTP_0_9
             [method, path] = words
             if method != http.HTTP_GET:
               raise http.HttpBadRequest("Bad HTTP/0.9 request type (%r)" % method)
           else:
             raise http.HttpBadRequest("Bad request syntax (%r)" % start_line)
           return http.HttpClientToServerStartLine(method, path, version)
       class HttpServerRequestExecutor(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.HTTP_0_9
         # Error message settings
         error_message_format = DEFAULT_ERROR_MESSAGE
         error_content_type = DEFAULT_ERROR_CONTENT_TYPE
         responses = BaseHTTPServer.BaseHTTPRequestHandler.responses
         # Timeouts in seconds for socket layer
         WRITE_TIMEOUT = 10
         READ_TIMEOUT = 10
         CLOSE_TIMEOUT = 1
         def __init__(self, server, sock, client_addr):
           """Initializes this class.
           """
           self.server = server
           self.sock = sock
           self.client_addr = client_addr
           self.request_msg = http.HttpMessage()
           self.response_msg = http.HttpMessage()
           self.response_msg.start_line = \
             http.HttpServerToClientStartLine(version=self.default_request_version,
                                              code=None, reason=None)
           # Disable Python's timeout
           self.sock.settimeout(None)
           # Operate in non-blocking mode
           self.sock.setblocking(0)
           logging.debug("Connection from %s:%s", client_addr[0], client_addr[1])
           try:
             request_msg_reader = None
             force_close = True
             try:
               # Do the secret SSL handshake
               if self.server.using_ssl:
                 self.sock.set_accept_state()
                 try:
                   http.Handshake(self.sock, self.WRITE_TIMEOUT)
                 except http.HttpSessionHandshakeUnexpectedEOF:
                   # Ignore rest
                   return
               try:
                 try:
                   request_msg_reader = self._ReadRequest()
                   # RFC2616, 14.23: All Internet-based HTTP/1.1 servers MUST respond
                   # with a 400 (Bad Request) status code to any HTTP/1.1 request
                   # message which lacks a Host header field.
                   if (self.request_msg.start_line.version == http.HTTP_1_1 and
                       http.HTTP_HOST not in self.request_msg.headers):
                     raise http.HttpBadRequest(message="Missing Host header")
                   self._HandleRequest()
                   # Only wait for client to close if we didn't have any exception.
                   force_close = False
                 except http.HttpException, err:
                   self._SetErrorStatus(err)
               finally:
                 # Try to send a response
                 self._SendResponse()
             finally:
               http.ShutdownConnection(sock, self.CLOSE_TIMEOUT, self.WRITE_TIMEOUT,
                                       request_msg_reader, force_close)
             self.sock.close()
             self.sock = None
           finally:
             logging.debug("Disconnected %s:%s", client_addr[0], client_addr[1])
         def _ReadRequest(self):
           """Reads a request sent by client.
           """
           try:
             request_msg_reader = \
               _HttpClientToServerMessageReader(self.sock, self.request_msg,
                                                self.READ_TIMEOUT)
           except http.HttpSocketTimeout:
             raise http.HttpError("Timeout while reading request")
           except socket.error, err:
             raise http.HttpError("Error reading request: %s" % err)
           self.response_msg.start_line.version = self.request_msg.start_line.version
           return request_msg_reader
         def _HandleRequest(self):
           """Calls the handler function for the current request.
           """
           handler_context = _HttpServerRequest(self.request_msg.start_line.method,
                                                self.request_msg.start_line.path,
                                                self.request_msg.headers,
                                                self.request_msg.body)
           logging.debug("Handling request %r", handler_context)
           try:
             try:
               # Authentication, etc.
               self.server.PreHandleRequest(handler_context)
               # Call actual request handler
               result = self.server.HandleRequest(handler_context)
             except (http.HttpException, KeyboardInterrupt, SystemExit):
               raise
             except Exception, err:
               logging.exception("Caught exception")
               raise http.HttpInternalServerError(message=str(err))
             except:
               logging.exception("Unknown exception")
               raise http.HttpInternalServerError(message="Unknown error")
             if not isinstance(result, basestring):
               raise http.HttpError("Handler function didn't return string type")
             self.response_msg.start_line.code = http.HTTP_OK
             self.response_msg.headers = handler_context.resp_headers
             self.response_msg.body = result
           finally:
             # No reason to keep this any longer, even for exceptions
             handler_context.private = None
         def _SendResponse(self):
           """Sends the response to the client.
           """
           if self.response_msg.start_line.code is None:
             return
           if not self.response_msg.headers:
             self.response_msg.headers = {}
           self.response_msg.headers.update({
             # TODO: Keep-alive is not supported
             http.HTTP_CONNECTION: "close",
             http.HTTP_DATE: _DateTimeHeader(),
             http.HTTP_SERVER: http.HTTP_GANETI_VERSION,
             })
           # Get response reason based on code
           response_code = self.response_msg.start_line.code
           if response_code in self.responses:
             response_reason = self.responses[response_code][0]
           else:
             response_reason = ""
           self.response_msg.start_line.reason = response_reason
           logging.info("%s:%s %s %s", self.client_addr[0], self.client_addr[1],
                        self.request_msg.start_line, response_code)
           try:
             _HttpServerToClientMessageWriter(self.sock, self.request_msg,
                                              self.response_msg, self.WRITE_TIMEOUT)
           except http.HttpSocketTimeout:
             raise http.HttpError("Timeout while sending response")
           except socket.error, err:
             raise http.HttpError("Error sending response: %s" % err)
         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_msg.start_line.code = err.code
           headers = {}
           if err.headers:
             headers.update(err.headers)
           headers[http.HTTP_CONTENT_TYPE] = self.error_content_type
           self.response_msg.headers = headers
           self.response_msg.body = self._FormatErrorMessage(values)
         def _FormatErrorMessage(self, values):
           """Formats the body of an error message.
           @type values: dict
           @param values: dictionary with keys code, message and explain.
           @rtype: string
           @return: the body of the message
           """
           return self.error_message_format % values
       class HttpServer(http.HttpBase, asyncore.dispatcher):
         """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_params=None, ssl_verify_peer=False,
                      request_executor_class=None):
           """Initializes the HTTP server
           @type mainloop: ganeti.daemon.Mainloop
           @param mainloop: Mainloop used to poll for I/O events
           @type local_address: string
           @param local_address: Local IP address to bind to
           @type port: int
           @param port: TCP port to listen on
           @type ssl_params: HttpSslParams
           @param ssl_params: SSL key and certificate
           @type ssl_verify_peer: bool
           @param ssl_verify_peer: Whether to require client certificate
               and compare it with our certificate
           @type request_executor_class: class
           @param request_executor_class: an class derived from the
               HttpServerRequestExecutor class
           """
           http.HttpBase.__init__(self)
           asyncore.dispatcher.__init__(self)
           if request_executor_class is None:
             self.request_executor = HttpServerRequestExecutor
           else:
             self.request_executor = request_executor_class
           self.mainloop = mainloop
           self.local_address = local_address
           self.port = port
           self.socket = self._CreateSocket(ssl_params, ssl_verify_peer)
           # Allow port to be reused
           self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
           self._children = []
           self.set_socket(self.socket)
           self.accepting = True
           mainloop.RegisterSignal(self)
         def Start(self):
           self.socket.bind((self.local_address, self.port))
           self.socket.listen(1024)
         def Stop(self):
           self.socket.close()
         def handle_accept(self):
           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, _ = 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, _ = 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
           """
           # pylint: disable-msg=W0212
           (connection, client_addr) = self.socket.accept()
           self._CollectChildren(False)
           pid = os.fork()
           if pid == 0:
             # Child process
             try:
               # The client shouldn't keep the listening socket open. If the parent
               # process is restarted, it would fail when there's already something
               # listening (in this case its own child from a previous run) on the
               # same port.
               try:
                 self.socket.close()
               except socket.error:
                 pass
               self.socket = None
               # In case the handler code uses temporary files
               utils.ResetTempfileModule()
               self.request_executor(self, connection, client_addr)
             except Exception: # pylint: disable-msg=W0703
               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 PreHandleRequest(self, req):
           """Called before handling a request.
           Can be overridden by a subclass.
           """
         def HandleRequest(self, req):
           """Handles a request.
           Must be overridden by subclass.
           """
           raise NotImplementedError()

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