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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 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.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()

      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()