Synnefo » snf-ganeti

	lib/http/__init__.py \

	lib/http/client.py \

	lib/http/server.py

"""HTTP module.

class HttpError(Exception):

  """Internal exception for HTTP errors.

  This should only be used for internal error reporting.

  """

def ShutdownConnection(poller, sock, close_timeout, write_timeout, msgreader,

                       force):

  """Closes the connection.

  """

  poller = select.poll()

  #print msgreader.peer_will_close, force

  if msgreader and msgreader.peer_will_close and not force:

    # Wait for peer to close

    try:

      # Check whether it's actually closed

      if not SocketOperation(poller, sock, SOCKOP_RECV, 1, close_timeout):

        return

    except (socket.error, HttpError, HttpSocketTimeout):

      # Ignore errors at this stage

      pass

  # Close the connection from our side

  try:

    SocketOperation(poller, sock, SOCKOP_SHUTDOWN, socket.SHUT_RDWR,

                    write_timeout)

  except HttpSocketTimeout:

    raise HttpError("Timeout while shutting down connection")

  except socket.error, err:

    raise HttpError("Error while shutting down connection: %s" % err)

class HttpMessage(object):

  """Data structure for HTTP message.

  """

  def __init__(self):

    self.start_line = None

    self.headers = None

    self.body = None

    self.decoded_body = None

class HttpClientToServerStartLine(object):

  """Data structure for HTTP request start line.

  """

  def __init__(self, method, path, version):

    self.method = method

    self.path = path

    self.version = version

  def __str__(self):

    return "%s %s %s" % (self.method, self.path, self.version)

class HttpServerToClientStartLine(object):

  """Data structure for HTTP response start line.

  """

  def __init__(self, version, code, reason):

    self.version = version

    self.code = code

    self.reason = reason

  def __str__(self):

    return "%s %s %s" % (self.version, self.code, self.reason)

class HttpMessageWriter(object):

  """Writes an HTTP message to a socket.

  """

  def __init__(self, sock, msg, write_timeout):

    self._msg = msg

    self._PrepareMessage()

    buf = self._FormatMessage()

    poller = select.poll()

    while buf:

      # Send only 4 KB at a time

      data = buf[:4096]

      sent = SocketOperation(poller, sock, SOCKOP_SEND, data,

                             write_timeout)

      # Remove sent bytes

      buf = buf[sent:]

    assert not buf, "Message wasn't sent completely"

  def _PrepareMessage(self):

    """Prepares the HTTP message by setting mandatory headers.

    """

    # RFC2616, section 4.3: "The presence of a message-body in a request is

    # signaled by the inclusion of a Content-Length or Transfer-Encoding header

    # field in the request's message-headers."

    if self._msg.body:

      self._msg.headers[HTTP_CONTENT_LENGTH] = len(self._msg.body)

  def _FormatMessage(self):

    """Serializes the HTTP message into a string.

    """

    buf = StringIO()

    # Add start line

    buf.write(str(self._msg.start_line))

    buf.write("\r\n")

    # Add headers

    if self._msg.start_line.version != HTTP_0_9:

      for name, value in self._msg.headers.iteritems():

        buf.write("%s: %s\r\n" % (name, value))

    buf.write("\r\n")

    # Add message body if needed

    if self.HasMessageBody():

      buf.write(self._msg.body)

    elif self._msg.body:

      logging.warning("Ignoring message body")

    return buf.getvalue()

  def HasMessageBody(self):

    """Checks whether the HTTP message contains a body.

    Can be overriden by subclasses.

    """

    return bool(self._msg.body)

class HttpMessageReader(object):

  """Reads HTTP message from socket.

  """

  # Length limits

  START_LINE_LENGTH_MAX = None

  HEADER_LENGTH_MAX = None

  # Parser state machine

  PS_START_LINE = "start-line"

  PS_HEADERS = "headers"

  PS_BODY = "entity-body"

  PS_COMPLETE = "complete"

  def __init__(self, sock, msg, read_timeout):

    self.sock = sock

    self.msg = msg

    self.poller = select.poll()

    self.start_line_buffer = None

    self.header_buffer = StringIO()

    self.body_buffer = StringIO()

    self.parser_status = self.PS_START_LINE

    self.content_length = None

    self.peer_will_close = None

    buf = ""

    eof = False

    while self.parser_status != self.PS_COMPLETE:

      data = SocketOperation(self.poller, sock, SOCKOP_RECV, 4096,

                             read_timeout)

      if data:

        buf += data

      else:

        eof = True

      # Do some parsing and error checking while more data arrives

      buf = self._ContinueParsing(buf, eof)

      # Must be done only after the buffer has been evaluated

      # TODO: Connection-length < len(data read) and connection closed

      if (eof and

          self.parser_status in (self.PS_START_LINE,

                                 self.PS_HEADERS)):

        raise HttpError("Connection closed prematurely")

    # Parse rest

    buf = self._ContinueParsing(buf, True)

    assert self.parser_status == self.PS_COMPLETE

    assert not buf, "Parser didn't read full response"

    msg.body = self.body_buffer.getvalue()

    # TODO: Content-type, error handling

    if msg.body:

      msg.decoded_body = HttpJsonConverter().Decode(msg.body)

    else:

      msg.decoded_body = None

    if msg.decoded_body:

      logging.debug("Message body: %s", msg.decoded_body)

  def _ContinueParsing(self, buf, eof):

    """Main function for HTTP message 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_START_LINE:

      # Expect start line

      while True:

        idx = buf.find("\r\n")

        # RFC2616, section 4.1: "In the interest of robustness, servers SHOULD

        # ignore any empty line(s) received where a Request-Line is expected.

        # In other words, if the server is reading the protocol stream at the

        # beginning of a message and receives a CRLF first, it should ignore

        # the CRLF."

        if idx == 0:

          # TODO: Limit number of CRLFs for safety?

          buf = buf[:2]

          continue

        if idx > 0:

          self.start_line_buffer = buf[:idx]

          self._CheckStartLineLength(len(self.start_line_buffer))

          # Remove status line, including CRLF

          buf = buf[idx + 2:]

          self.msg.start_line = self.ParseStartLine(self.start_line_buffer)

          self.parser_status = self.PS_HEADERS

        else:

          # Check whether incoming data is getting too large, otherwise we just

          # fill our read buffer.

          self._CheckStartLineLength(len(buf))

        break

    # TODO: Handle messages without headers

    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:

      # TODO: Implement max size for body_buffer

      self.body_buffer.write(buf)

      buf = ""

      # Check whether we've read everything

      #

      # RFC2616, section 4.4: "When a message-body is included with a message,

      # the transfer-length of that body is determined by one of the following

      # [...] 5. By the server closing the connection. (Closing the connection

      # cannot be used to indicate the end of a request body, since that would

      # leave no possibility for the server to send back a response.)"

      if (eof or

          self.content_length is None or

          (self.content_length is not None and

           self.body_buffer.tell() >= self.content_length)):

        self.parser_status = self.PS_COMPLETE

    return buf

  def _CheckStartLineLength(self, length):

    """Limits the start line buffer size.

    @type length: int

    @param length: Buffer size

    """

    if (self.START_LINE_LENGTH_MAX is not None and

        length > self.START_LINE_LENGTH_MAX):

      raise HttpError("Start line longer than %d chars" %

                       self.START_LINE_LENGTH_MAX)

  def _CheckHeaderLength(self, length):

    """Limits the header buffer size.

    @type length: int

    @param length: Buffer size

    """

    if (self.HEADER_LENGTH_MAX is not None and

        length > self.HEADER_LENGTH_MAX):

      raise HttpError("Headers longer than %d chars" % self.HEADER_LENGTH_MAX)

  def ParseStartLine(self, start_line):

    """Parses the start line of a message.

    Must be overriden by subclass.

    @type start_line: string

    @param start_line: Start line string

    """

    raise NotImplementedError()

  def _WillPeerCloseConnection(self):

    """Evaluate whether peer will close the connection.

    @rtype: bool

    @return: Whether peer will close the connection

    """

    # RFC2616, section 14.10: "HTTP/1.1 defines the "close" connection option

    # for the sender to signal that the connection will be closed after

    # completion of the response. For example,

    #

    #        Connection: close

    #

    # in either the request or the response header fields indicates that the

    # connection SHOULD NOT be considered `persistent' (section 8.1) after the

    # current request/response is complete."

    hdr_connection = self.msg.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.msg.start_line.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.msg.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.

    This function also adjusts internal variables based on header values.

    RFC2616, section 4.3: "The presence of a message-body in a request is

    signaled by the inclusion of a Content-Length or Transfer-Encoding header

    field in the request's message-headers."

    """

    # Parse headers

    self.header_buffer.seek(0, 0)

    self.msg.headers = mimetools.Message(self.header_buffer, 0)

    self.peer_will_close = self._WillPeerCloseConnection()

    # Do we have a Content-Length header?

    hdr_content_length = self.msg.headers.get(HTTP_CONTENT_LENGTH, None)

    if hdr_content_length:

      try:

        self.content_length = int(hdr_content_length)

      except ValueError:

        self.content_length = None

      if self.content_length is not None and self.content_length < 0:

        self.content_length = None

    # 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.peer_will_close = True

#

#

# 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 client module.

"""

import BaseHTTPServer

import cgi

import logging

import OpenSSL

import os

import select

import socket

import sys

import time

import signal

import errno

import threading

from ganeti import constants

from ganeti import serializer

from ganeti import workerpool

from ganeti import utils

from ganeti import http

HTTP_CLIENT_THREADS = 10

class HttpClientRequest(object):

  def __init__(self, host, port, method, path, headers=None, post_data=None,

               ssl_params=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

    @type ssl_params: HttpSslParams

    @param ssl_params: SSL key and certificate

    @type ssl_verify_peer: bool

    @param ssl_verify_peer: Whether to compare our certificate with server's

                            certificate

    """

    if post_data is not None:

      assert method.upper() in (http.HTTP_POST, http.HTTP_PUT), \

        "Only POST and GET requests support sending data"

    assert path.startswith("/"), "Path must start with slash (/)"

    # Request attributes

    self.host = host

    self.port = port

    self.ssl_params = ssl_params

    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

    # Raw response

    self.response = None

    # Response attributes

    self.resp_version = None

    self.resp_status_code = None

    self.resp_reason = None

    self.resp_headers = None

    self.resp_body = None

class _HttpClientToServerMessageWriter(http.HttpMessageWriter):

  pass

class _HttpServerToClientMessageReader(http.HttpMessageReader):

  # Length limits

  START_LINE_LENGTH_MAX = 512

  HEADER_LENGTH_MAX = 4096

  def ParseStartLine(self, start_line):

    """Parses the status line sent by the server.

    """

    # Empty lines are skipped when reading

    assert start_line

    try:

      [version, status, reason] = start_line.split(None, 2)

    except ValueError:

      try:

        [version, status] = start_line.split(None, 1)

        reason = ""

      except ValueError:

        version = http.HTTP_0_9

    if version:

      version = version.upper()

    # 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 http.HttpError("Invalid status code (%r)" % start_line)

    return http.HttpServerToClientStartLine(version, status, reason)

class HttpClientRequestExecutor(http.HttpSocketBase):

  # Default headers

  DEFAULT_HEADERS = {

    http.HTTP_USER_AGENT: http.HTTP_GANETI_VERSION,

    # TODO: For keep-alive, don't send "Connection: close"

    http.HTTP_CONNECTION: "close",

    }

  # Timeouts in seconds for socket layer

  # TODO: Soft timeout instead of only socket timeout?

  # TODO: Make read timeout configurable per OpCode?

  CONNECT_TIMEOUT = 5

  WRITE_TIMEOUT = 10

  READ_TIMEOUT = None

  CLOSE_TIMEOUT = 1

  def __init__(self, req):

    """Initializes the HttpClientRequestExecutor class.

    @type req: HttpClientRequest

    @param req: Request object

    """

    http.HttpSocketBase.__init__(self)

    self.request = req

    self.poller = select.poll()

    try:

      # TODO: Implement connection caching/keep-alive

      self.sock = self._CreateSocket(req.ssl_params,

                                     req.ssl_verify_peer)

      # Disable Python's timeout

      self.sock.settimeout(None)

      # Operate in non-blocking mode

      self.sock.setblocking(0)

      response_msg_reader = None

      response_msg = None

      force_close = True

      self._Connect()

      try:

        self._SendRequest()

        (response_msg_reader, response_msg) = self._ReadResponse()

        # Only wait for server to close if we didn't have any exception.

        force_close = False

      finally:

        # TODO: Keep-alive is not supported, always close connection

        force_close = True

        http.ShutdownConnection(self.poller, self.sock,

                                self.CLOSE_TIMEOUT, self.WRITE_TIMEOUT,

                                response_msg_reader, force_close)

      self.sock.close()

      self.sock = None

      req.response = response_msg

      req.resp_version = req.response.start_line.version

      req.resp_status_code = req.response.start_line.code

      req.resp_reason = req.response.start_line.reason

      req.resp_headers = req.response.headers

      req.resp_body = req.response.body

      req.success = True

      req.error = None

    except http.HttpError, err:

      req.success = False

      req.error = 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 http.HttpError("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 http.HttpError("Connection failed (%s: %s)" %

                             (connect_error, os.strerror(connect_error)))

    if not connected:

      # Wait for connection

      event = http.WaitForSocketCondition(self.poller, self.sock,

                                          select.POLLOUT, self.CONNECT_TIMEOUT)

      if event is None:

        raise http.HttpError("Timeout while connecting to server")

      # Get error code

      connect_error = self.sock.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)

      if connect_error != 0:

        raise http.HttpError("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.

    """

    # Headers

    send_headers = self.DEFAULT_HEADERS.copy()

    if self.request.headers:

      send_headers.update(self.request.headers)

    send_headers[http.HTTP_HOST] = "%s:%s" % (self.request.host, self.request.port)

    # Response message

    msg = http.HttpMessage()

    # Combine request line. We only support HTTP/1.0 (no chunked transfers and

    # no keep-alive).

    # TODO: For keep-alive, change to HTTP/1.1

    msg.start_line = \

      http.HttpClientToServerStartLine(method=self.request.method.upper(),

                                       path=self.request.path, version=http.HTTP_1_0)

    msg.headers = send_headers

    msg.body = self.request.post_data

    try:

      _HttpClientToServerMessageWriter(self.sock, msg, self.WRITE_TIMEOUT)

    except http.HttpSocketTimeout:

      raise http.HttpError("Timeout while sending request")

    except socket.error, err:

      raise http.HttpError("Error sending request: %s" % err)

  def _ReadResponse(self):

    """Read response from server.

    """

    response_msg = http.HttpMessage()

    try:

      response_msg_reader = \

        _HttpServerToClientMessageReader(self.sock, response_msg,

                                         self.READ_TIMEOUT)

    except http.HttpSocketTimeout:

      raise http.HttpError("Timeout while reading response")

    except socket.error, err:

      raise http.HttpError("Error reading response: %s" % err)

    return (response_msg_reader, response_msg)

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()

#

#

# 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 select

import socket

import time

import signal

from ganeti import constants

from ganeti import serializer

from ganeti import utils

from ganeti import http

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():

  """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))

class _HttpServerRequest(object):

  """Data structure for HTTP request on server side.

  """

  def __init__(self, request_msg):

    # Request attributes

    self.request_method = request_msg.start_line.method

    self.request_path = request_msg.start_line.path

    self.request_headers = request_msg.headers

    self.request_body = request_msg.decoded_body

    # Response attributes

    self.resp_headers = {}

class _HttpServerToClientMessageWriter(http.HttpMessageWriter):

  """Writes an HTTP response to client.

  """

  def __init__(self, sock, request_msg, response_msg, write_timeout):

    """TODO

    """

    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.poller = select.poll()

    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.info("Connection from %s:%s", client_addr[0], client_addr[1])

    try:

      request_msg_reader = None

      force_close = True

      try:

        try:

          try:

            request_msg_reader = self._ReadRequest()

            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(self.poller, sock,

                                self.CLOSE_TIMEOUT, self.WRITE_TIMEOUT,

                                request_msg_reader, force_close)

      self.sock.close()

      self.sock = None

    finally:

      logging.info("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)

    try:

      result = self.server.HandleRequest(handler_context)

    except (http.HttpException, KeyboardInterrupt, SystemExit):

      raise

    except Exception, err:

      logging.exception("Caught exception")

      raise http.HttpInternalError(message=str(err))

    except:

      logging.exception("Unknown exception")

      raise http.HttpInternalError(message="Unknown error")

    # TODO: Content-type

    encoder = http.HttpJsonConverter()

    self.response_msg.start_line.code = http.HTTP_OK

    self.response_msg.body = encoder.Encode(result)

    self.response_msg.headers = handler_context.resp_headers

    self.response_msg.headers[http.HTTP_CONTENT_TYPE] = encoder.CONTENT_TYPE

  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

    self.response_msg.headers = {

      http.HTTP_CONTENT_TYPE: self.error_content_type,

      }

    self.response_msg.body = self.error_message_format % values

class HttpServer(http.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_params=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_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

    """

    http.HttpSocketBase.__init__(self)

    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 = []

    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

      try:

        _HttpServerRequestExecutor(self, connection, client_addr)

      except Exception:

        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):

    """Handles a request.

    Must be overriden by subclass.

    """

    raise NotImplementedError()