#!/usr/bin/env python

#

# Copyright 2007 Google Inc.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#     http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

#

"""Tool for performing authenticated RPCs against App Engine."""

import cookielib

import logging

import os

import re

import socket

import sys

import urllib

import urllib2

https_handler = urllib2.HTTPSHandler

uses_cert_verification = False

certpath = os.path.join(os.path.dirname(__file__), "cacerts.txt")

cert_file_available = os.path.exists(certpath)

try:

  import https_wrapper

  if cert_file_available:

    https_handler = lambda: https_wrapper.CertValidatingHTTPSHandler(

        ca_certs=certpath)

    uses_cert_verification = True

except ImportError:

  pass

logger = logging.getLogger('google.appengine.tools.appengine_rpc')

def GetPlatformToken(os_module=os, sys_module=sys, platform=sys.platform):

  """Returns a 'User-agent' token for the host system platform.

  Args:

    os_module, sys_module, platform: Used for testing.

  Returns:

    String containing the platform token for the host system.

  """

  if hasattr(sys_module, "getwindowsversion"):

    windows_version = sys_module.getwindowsversion()

    version_info = ".".join(str(i) for i in windows_version[:4])

    return platform + "/" + version_info

  elif hasattr(os_module, "uname"):

    uname = os_module.uname()

    return "%s/%s" % (uname[0], uname[2])

  else:

    return "unknown"

def HttpRequestToString(req, include_data=True):

  """Converts a urllib2.Request to a string.

  Args:

    req: urllib2.Request

  Returns:

    Multi-line string representing the request.

  """

  headers = ""

  for header in req.header_items():

    headers += "%s: %s\n" % (header[0], header[1])

  template = ("%(method)s %(selector)s %(type)s/1.1\n"

              "Host: %(host)s\n"

              "%(headers)s")

  if include_data:

    template = template + "\n%(data)s"

  return template % {

      'method' : req.get_method(),

      'selector' : req.get_selector(),

      'type' : req.get_type().upper(),

      'host' : req.get_host(),

      'headers': headers,

      'data': req.get_data(),

      }

class ClientLoginError(urllib2.HTTPError):

  """Raised to indicate there was an error authenticating with ClientLogin."""

  def __init__(self, url, code, msg, headers, args):

    urllib2.HTTPError.__init__(self, url, code, msg, headers, None)

    self.args = args

    self.reason = args["Error"]

  def read(self):

    return '%d %s: %s' % (self.code, self.msg, self.reason)

class AbstractRpcServer(object):

  """Provides a common interface for a simple RPC server."""

  def __init__(self, host, auth_function, user_agent, source,

               host_override=None, extra_headers=None, save_cookies=False,

               auth_tries=3, account_type=None, debug_data=True, secure=True):

    """Creates a new HttpRpcServer.

    Args:

      host: The host to send requests to.

      auth_function: A function that takes no arguments and returns an

        (email, password) tuple when called. Will be called if authentication

        is required.

      user_agent: The user-agent string to send to the server. Specify None to

        omit the user-agent header.

      source: The source to specify in authentication requests.

      host_override: The host header to send to the server (defaults to host).

      extra_headers: A dict of extra headers to append to every request. Values

        supplied here will override other default headers that are supplied.

      save_cookies: If True, save the authentication cookies to local disk.

        If False, use an in-memory cookiejar instead.  Subclasses must

        implement this functionality.  Defaults to False.

      auth_tries: The number of times to attempt auth_function before failing.

      account_type: One of GOOGLE, HOSTED_OR_GOOGLE, or None for automatic.

      debug_data: Whether debugging output should include data contents.

    """

    if secure:

      self.scheme = "https"

    else:

      self.scheme = "http"

    self.host = host

    self.host_override = host_override

    self.auth_function = auth_function

    self.source = source

    self.authenticated = False

    self.auth_tries = auth_tries

    self.debug_data = debug_data

    self.account_type = account_type

    self.extra_headers = {}

    if user_agent:

      self.extra_headers["User-Agent"] = user_agent

    if extra_headers:

      self.extra_headers.update(extra_headers)

    self.save_cookies = save_cookies

    self.cookie_jar = cookielib.MozillaCookieJar()

    self.opener = self._GetOpener()

    if self.host_override:

      logger.info("Server: %s; Host: %s", self.host, self.host_override)

    else:

      logger.info("Server: %s", self.host)

    if ((self.host_override and self.host_override == "localhost") or

        self.host == "localhost" or self.host.startswith("localhost:")):

      self._DevAppServerAuthenticate()

  def _GetOpener(self):

    """Returns an OpenerDirector for making HTTP requests.

    Returns:

      A urllib2.OpenerDirector object.

    """

    raise NotImplemented()

  def _CreateRequest(self, url, data=None):

    """Creates a new urllib request."""

    req = urllib2.Request(url, data=data)

    if self.host_override:

      req.add_header("Host", self.host_override)

    for key, value in self.extra_headers.iteritems():

      req.add_header(key, value)

    return req

  def _GetAuthToken(self, email, password):

    """Uses ClientLogin to authenticate the user, returning an auth token.

    Args:

      email:    The user's email address

      password: The user's password

    Raises:

      ClientLoginError: If there was an error authenticating with ClientLogin.

      HTTPError: If there was some other form of HTTP error.

    Returns:

      The authentication token returned by ClientLogin.

    """

    account_type = self.account_type

    if not account_type:

      if (self.host.split(':')[0].endswith(".google.com")

          or (self.host_override

              and self.host_override.split(':')[0].endswith(".google.com"))):

        account_type = "HOSTED_OR_GOOGLE"

      else:

        account_type = "GOOGLE"

    data = {

        "Email": email,

        "Passwd": password,

        "service": "ah",

        "source": self.source,

        "accountType": account_type

    }

    req = self._CreateRequest(

        url="https://www.google.com/accounts/ClientLogin",

        data=urllib.urlencode(data))

    try:

      response = self.opener.open(req)

      response_body = response.read()

      response_dict = dict(x.split("=")

                           for x in response_body.split("\n") if x)

      return response_dict["Auth"]

    except urllib2.HTTPError, e:

      if e.code == 403:

        body = e.read()

        response_dict = dict(x.split("=", 1) for x in body.split("\n") if x)

        raise ClientLoginError(req.get_full_url(), e.code, e.msg,

                               e.headers, response_dict)

      else:

        raise

  def _GetAuthCookie(self, auth_token):

    """Fetches authentication cookies for an authentication token.

    Args:

      auth_token: The authentication token returned by ClientLogin.

    Raises:

      HTTPError: If there was an error fetching the authentication cookies.

    """

    continue_location = "http://localhost/"

    args = {"continue": continue_location, "auth": auth_token}

    login_path = os.environ.get("APPCFG_LOGIN_PATH", "/_ah")

    req = self._CreateRequest("%s://%s%s/login?%s" %

                              (self.scheme, self.host, login_path,

                               urllib.urlencode(args)))

    try:

      response = self.opener.open(req)

    except urllib2.HTTPError, e:

      response = e

    if (response.code != 302 or

        response.info()["location"] != continue_location):

      raise urllib2.HTTPError(req.get_full_url(), response.code, response.msg,

                              response.headers, response.fp)

    self.authenticated = True

  def _Authenticate(self):

    """Authenticates the user.

    The authentication process works as follows:

     1) We get a username and password from the user

     2) We use ClientLogin to obtain an AUTH token for the user

        (see http://code.google.com/apis/accounts/AuthForInstalledApps.html).

     3) We pass the auth token to /_ah/login on the server to obtain an

        authentication cookie. If login was successful, it tries to redirect

        us to the URL we provided.

    If we attempt to access the upload API without first obtaining an

    authentication cookie, it returns a 401 response and directs us to

    authenticate ourselves with ClientLogin.

    """

    for unused_i in range(self.auth_tries):

      credentials = self.auth_function()

      try:

        auth_token = self._GetAuthToken(credentials[0], credentials[1])

      except ClientLoginError, e:

        if e.reason == "BadAuthentication":

          print >>sys.stderr, "Invalid username or password."

          continue

        if e.reason == "CaptchaRequired":

          print >>sys.stderr, (

              "Please go to\n"

              "https://www.google.com/accounts/DisplayUnlockCaptcha\n"

              "and verify you are a human.  Then try again.")

          break

        if e.reason == "NotVerified":

          print >>sys.stderr, "Account not verified."

          break

        if e.reason == "TermsNotAgreed":

          print >>sys.stderr, "User has not agreed to TOS."

          break

        if e.reason == "AccountDeleted":

          print >>sys.stderr, "The user account has been deleted."

          break

        if e.reason == "AccountDisabled":

          print >>sys.stderr, "The user account has been disabled."

          break

        if e.reason == "ServiceDisabled":

          print >>sys.stderr, ("The user's access to the service has been "

                               "disabled.")

          break

        if e.reason == "ServiceUnavailable":

          print >>sys.stderr, "The service is not available; try again later."

          break

        raise

      self._GetAuthCookie(auth_token)

      return

  def _DevAppServerAuthenticate(self):

    """Authenticates the user on the dev_appserver."""

    credentials = self.auth_function()

    self.extra_headers["Cookie"] = ('dev_appserver_login="%s:True"; Path=/;'  %

                                    (credentials[0],))

  def Send(self, request_path, payload="",

           content_type="application/octet-stream",

           timeout=None,

           **kwargs):

    """Sends an RPC and returns the response.

    Args:

      request_path: The path to send the request to, eg /api/appversion/create.

      payload: The body of the request, or None to send an empty request.

      content_type: The Content-Type header to use.

      timeout: timeout in seconds; default None i.e. no timeout.

        (Note: for large requests on OS X, the timeout doesn't work right.)

      kwargs: Any keyword arguments are converted into query string parameters.

    Returns:

      The response body, as a string.

    """

    old_timeout = socket.getdefaulttimeout()

    socket.setdefaulttimeout(timeout)

    try:

      tries = 0

      auth_tried = False

      while True:

        tries += 1

        args = dict(kwargs)

        url = "%s://%s%s?%s" % (self.scheme, self.host, request_path,

                                urllib.urlencode(args))

        req = self._CreateRequest(url=url, data=payload)

        req.add_header("Content-Type", content_type)

        req.add_header("X-appcfg-api-version", "1")

        try:

          logger.debug('Sending HTTP request:\n%s' %

                       HttpRequestToString(req, include_data=self.debug_data))

          f = self.opener.open(req)

          response = f.read()

          f.close()

          return response

        except urllib2.HTTPError, e:

          logger.debug("Got http error, this is try #%s" % tries)

          if tries > self.auth_tries:

            raise

          elif e.code == 401:

            if auth_tried:

              raise

            auth_tried = True

            self._Authenticate()

          elif e.code >= 500 and e.code < 600:

            continue

          elif e.code == 302:

            if auth_tried:

              raise

            auth_tried = True

            loc = e.info()["location"]

            logger.debug("Got 302 redirect. Location: %s" % loc)

            if loc.startswith("https://www.google.com/accounts/ServiceLogin"):

              self._Authenticate()

            elif re.match(r"https://www.google.com/a/[a-z0-9.-]+/ServiceLogin",

                          loc):

              self.account_type = "HOSTED"

              self._Authenticate()

            elif loc.startswith("http://%s/_ah/login" % (self.host,)):

              self._DevAppServerAuthenticate()

          else:

            raise

    finally:

      socket.setdefaulttimeout(old_timeout)

class HttpRpcServer(AbstractRpcServer):

  """Provides a simplified RPC-style interface for HTTP requests."""

  DEFAULT_COOKIE_FILE_PATH = "~/.appcfg_cookies"

  def _Authenticate(self):

    """Save the cookie jar after authentication."""

    if cert_file_available and not uses_cert_verification:

      logger.warn("ssl module not found. Without this the identity of the "

                  "remote host cannot be verified, and connections are NOT "

                  "secure. To fix this, please install the ssl module from "

                  "http://pypi.python.org/pypi/ssl")

    super(HttpRpcServer, self)._Authenticate()

    if self.cookie_jar.filename is not None and self.save_cookies:

      logger.info("Saving authentication cookies to %s" %

                  self.cookie_jar.filename)

      self.cookie_jar.save()

  def _GetOpener(self):

    """Returns an OpenerDirector that supports cookies and ignores redirects.

    Returns:

      A urllib2.OpenerDirector object.

    """

    opener = urllib2.OpenerDirector()

    opener.add_handler(urllib2.ProxyHandler())

    opener.add_handler(urllib2.UnknownHandler())

    opener.add_handler(urllib2.HTTPHandler())

    opener.add_handler(urllib2.HTTPDefaultErrorHandler())

    opener.add_handler(https_handler())

    opener.add_handler(urllib2.HTTPErrorProcessor())

    if self.save_cookies:

      self.cookie_jar.filename = os.path.expanduser(

          HttpRpcServer.DEFAULT_COOKIE_FILE_PATH)

      if os.path.exists(self.cookie_jar.filename):

        try:

          self.cookie_jar.load()

          self.authenticated = True

          logger.info("Loaded authentication cookies from %s" %

                      self.cookie_jar.filename)

        except (OSError, IOError, cookielib.LoadError), e:

          logger.debug("Could not load authentication cookies; %s: %s",

                       e.__class__.__name__, e)

          self.cookie_jar.filename = None

      else:

        try:

          fd = os.open(self.cookie_jar.filename, os.O_CREAT, 0600)

          os.close(fd)

        except (OSError, IOError), e:

          logger.debug("Could not create authentication cookies file; %s: %s",

                       e.__class__.__name__, e)

          self.cookie_jar.filename = None

    opener.add_handler(urllib2.HTTPCookieProcessor(self.cookie_jar))

    return opener