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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 client module.

"""

import os

import select

import socket

import errno

import threading

from ganeti import workerpool

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 (TypeError, ValueError):

      status = -1

    if status == -1:

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

    return http.HttpServerToClientStartLine(version, status, reason)

class HttpClientRequestExecutor(http.HttpBase):

  # 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.HttpBase.__init__(self)

    self.request = req

    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.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.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.

    # Do the secret SSL handshake

    if self.using_ssl:

      self.sock.set_connect_state() # pylint: disable-msg=E1103

      try:

        http.Handshake(self.sock, self.WRITE_TIMEOUT)

      except http.HttpSessionHandshakeUnexpectedEOF:

        raise http.HttpError("Server closed connection during SSL handshake")

  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

    @return: 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()