# -*- coding: utf-8 -*-
##############################################################################
#
#    OpenERP, Open Source Management Solution
#    Copyright (C) 2011-2012 OpenERP s.a. (<http://openerp.com>).
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as
#    published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
##############################################################################

"""

WSGI stack, common code.

"""

import httplib
import urllib
import xmlrpclib
import StringIO

import errno
import logging
import os
import signal
import sys
import threading
import traceback

import openerp
import openerp.modules
import openerp.tools.config as config
from ..service import websrv_lib

_logger = logging.getLogger(__name__)

# XML-RPC fault codes. Some care must be taken when changing these: the
# constants are also defined client-side and must remain in sync.
# User code must use the exceptions defined in ``openerp.exceptions`` (not
# create directly ``xmlrpclib.Fault`` objects).
RPC_FAULT_CODE_CLIENT_ERROR = 1 # indistinguishable from app. error.
RPC_FAULT_CODE_APPLICATION_ERROR = 1
RPC_FAULT_CODE_WARNING = 2
RPC_FAULT_CODE_ACCESS_DENIED = 3
RPC_FAULT_CODE_ACCESS_ERROR = 4

# The new (6.1) versioned RPC paths.
XML_RPC_PATH = '/openerp/xmlrpc'
XML_RPC_PATH_1 = '/openerp/xmlrpc/1'
JSON_RPC_PATH = '/openerp/jsonrpc'
JSON_RPC_PATH_1 = '/openerp/jsonrpc/1'

def xmlrpc_return(start_response, service, method, params, legacy_exceptions=False):
    """
    Helper to call a service's method with some params, using a wsgi-supplied
    ``start_response`` callback.

    This is the place to look at to see the mapping between core exceptions
    and XML-RPC fault codes.
    """
    # Map OpenERP core exceptions to XML-RPC fault codes. Specific exceptions
    # defined in ``openerp.exceptions`` are mapped to specific fault codes;
    # all the other exceptions are mapped to the generic
    # RPC_FAULT_CODE_APPLICATION_ERROR value.
    # This also mimics SimpleXMLRPCDispatcher._marshaled_dispatch() for
    # exception handling.
    try:
        result = openerp.netsvc.dispatch_rpc(service, method, params)
        response = xmlrpclib.dumps((result,), methodresponse=1, allow_none=False, encoding=None)
    except Exception, e:
        if legacy_exceptions:
            response = xmlrpc_handle_exception_legacy(e)
        else:
            response = xmlrpc_handle_exception(e)
    start_response("200 OK", [('Content-Type','text/xml'), ('Content-Length', str(len(response)))])
    return [response]

def xmlrpc_handle_exception(e):
    if isinstance(e, openerp.osv.osv.except_osv): # legacy
        fault = xmlrpclib.Fault(RPC_FAULT_CODE_WARNING, openerp.tools.ustr(e.value))
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    elif isinstance(e, openerp.exceptions.Warning):
        fault = xmlrpclib.Fault(RPC_FAULT_CODE_WARNING, str(e))
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    elif isinstance (e, openerp.exceptions.AccessError):
        fault = xmlrpclib.Fault(RPC_FAULT_CODE_ACCESS_ERROR, str(e))
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    elif isinstance(e, openerp.exceptions.AccessDenied):
        fault = xmlrpclib.Fault(RPC_FAULT_CODE_ACCESS_DENIED, str(e))
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    elif isinstance(e, openerp.exceptions.DeferredException):
        info = e.traceback
        # Which one is the best ?
        formatted_info = "".join(traceback.format_exception(*info))
        #formatted_info = openerp.tools.exception_to_unicode(e) + '\n' + info
        fault = xmlrpclib.Fault(RPC_FAULT_CODE_APPLICATION_ERROR, formatted_info)
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    else:
        if hasattr(e, 'message') and e.message == 'AccessDenied': # legacy
            fault = xmlrpclib.Fault(RPC_FAULT_CODE_ACCESS_DENIED, str(e))
            response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
        else:
            info = sys.exc_info()
            # Which one is the best ?
            formatted_info = "".join(traceback.format_exception(*info))
            #formatted_info = openerp.tools.exception_to_unicode(e) + '\n' + info
            fault = xmlrpclib.Fault(RPC_FAULT_CODE_APPLICATION_ERROR, formatted_info)
            response = xmlrpclib.dumps(fault, allow_none=None, encoding=None)
    return response

def xmlrpc_handle_exception_legacy(e):
    if isinstance(e, openerp.osv.osv.except_osv):
        fault = xmlrpclib.Fault('warning -- ' + e.name + '\n\n' + e.value, '')
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    elif isinstance(e, openerp.exceptions.Warning):
        fault = xmlrpclib.Fault('warning -- Warning\n\n' + str(e), '')
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    elif isinstance(e, openerp.exceptions.AccessError):
        fault = xmlrpclib.Fault('warning -- AccessError\n\n' + str(e), '')
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    elif isinstance(e, openerp.exceptions.AccessDenied):
        fault = xmlrpclib.Fault('AccessDenied', str(e))
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    elif isinstance(e, openerp.exceptions.DeferredException):
        info = e.traceback
        formatted_info = "".join(traceback.format_exception(*info))
        fault = xmlrpclib.Fault(openerp.tools.ustr(e.message), formatted_info)
        response = xmlrpclib.dumps(fault, allow_none=False, encoding=None)
    else:
        info = sys.exc_info()
        formatted_info = "".join(traceback.format_exception(*info))
        fault = xmlrpclib.Fault(openerp.tools.exception_to_unicode(e), formatted_info)
        response = xmlrpclib.dumps(fault, allow_none=None, encoding=None)
    return response

def wsgi_xmlrpc_1(environ, start_response):
    """ The main OpenERP WSGI handler."""
    if environ['REQUEST_METHOD'] == 'POST' and environ['PATH_INFO'].startswith(XML_RPC_PATH_1):
        length = int(environ['CONTENT_LENGTH'])
        data = environ['wsgi.input'].read(length)

        params, method = xmlrpclib.loads(data)

        path = environ['PATH_INFO'][len(XML_RPC_PATH_1):]
        if path.startswith('/'): path = path[1:]
        if path.endswith('/'): path = path[:-1]
        path = path.split('/')

        # All routes are hard-coded.

        # No need for a db segment.
        if len(path) == 1:
            service = path[0]

            if service == 'common':
                if method in ('server_version',):
                    service = 'db'
            return xmlrpc_return(start_response, service, method, params)

        # A db segment must be given.
        elif len(path) == 2:
            service, db_name = path
            params = (db_name,) + params

            return xmlrpc_return(start_response, service, method, params)

        # A db segment and a model segment must be given.
        elif len(path) == 3 and path[0] == 'model':
            service, db_name, model_name = path
            params = (db_name,) + params[:2] + (model_name,) + params[2:]
            service = 'object'
            return xmlrpc_return(start_response, service, method, params)

        # The body has been read, need to raise an exception (not return None).
        fault = xmlrpclib.Fault(RPC_FAULT_CODE_CLIENT_ERROR, '')
        response = xmlrpclib.dumps(fault, allow_none=None, encoding=None)
        start_response("200 OK", [('Content-Type','text/xml'), ('Content-Length', str(len(response)))])
        return [response]

def wsgi_xmlrpc(environ, start_response):
    """ WSGI handler to return the versions."""
    if environ['REQUEST_METHOD'] == 'POST' and environ['PATH_INFO'].startswith(XML_RPC_PATH):
        length = int(environ['CONTENT_LENGTH'])
        data = environ['wsgi.input'].read(length)

        params, method = xmlrpclib.loads(data)

        path = environ['PATH_INFO'][len(XML_RPC_PATH):]
        if path.startswith('/'): path = path[1:]
        if path.endswith('/'): path = path[:-1]
        path = path.split('/')

        # All routes are hard-coded.

        if len(path) == 1 and path[0] == '' and method in ('version',):
            return xmlrpc_return(start_response, 'common', method, ())

        # The body has been read, need to raise an exception (not return None).
        fault = xmlrpclib.Fault(RPC_FAULT_CODE_CLIENT_ERROR, '')
        response = xmlrpclib.dumps(fault, allow_none=None, encoding=None)
        start_response("200 OK", [('Content-Type','text/xml'), ('Content-Length', str(len(response)))])
        return [response]

def wsgi_xmlrpc_legacy(environ, start_response):
    if environ['REQUEST_METHOD'] == 'POST' and environ['PATH_INFO'].startswith('/xmlrpc/'):
        length = int(environ['CONTENT_LENGTH'])
        data = environ['wsgi.input'].read(length)
        path = environ['PATH_INFO'][len('/xmlrpc/'):] # expected to be one of db, object, ...

        params, method = xmlrpclib.loads(data)
        return xmlrpc_return(start_response, path, method, params, True)

def wsgi_jsonrpc(environ, start_response):
    pass

def wsgi_webdav(environ, start_response):
    pi = environ['PATH_INFO']
    if environ['REQUEST_METHOD'] == 'OPTIONS' and pi in ['*','/']:
        return return_options(environ, start_response)
    elif pi.startswith('/webdav'):
        http_dir = websrv_lib.find_http_service(pi)
        if http_dir:
            path = pi[len(http_dir.path):]
            if path.startswith('/'):
                environ['PATH_INFO'] = path
            else:
                environ['PATH_INFO'] = '/' + path
            return http_to_wsgi(http_dir)(environ, start_response)

def return_options(environ, start_response):
    # Microsoft specific header, see
    # http://www.ibm.com/developerworks/rational/library/2089.html
    if 'Microsoft' in environ.get('User-Agent', ''):
        options = [('MS-Author-Via', 'DAV')]
    else:
        options = []
    options += [('DAV', '1 2'), ('Allow', 'GET HEAD PROPFIND OPTIONS REPORT')]
    start_response("200 OK", [('Content-Length', str(0))] + options)
    return []

def http_to_wsgi(http_dir):
    """
    Turn a BaseHTTPRequestHandler into a WSGI entry point.

    Actually the argument is not a bare BaseHTTPRequestHandler but is wrapped
    (as a class, so it needs to be instanciated) in a HTTPDir.

    This code is adapted from wbsrv_lib.MultiHTTPHandler._handle_one_foreign().
    It is a temporary solution: the HTTP sub-handlers (in particular the
    document_webdav addon) have to be WSGIfied.
    """
    def wsgi_handler(environ, start_response):

        headers = {}
        for key, value in environ.items():
            if key.startswith('HTTP_'):
                key = key[5:].replace('_', '-').title()
                headers[key] = value
            if key == 'CONTENT_LENGTH':
                key = key.replace('_', '-').title()
                headers[key] = value
        if environ.get('Content-Type'):
            headers['Content-Type'] = environ['Content-Type']

        path = urllib.quote(environ.get('PATH_INFO', ''))
        if environ.get('QUERY_STRING'):
            path += '?' + environ['QUERY_STRING']

        request_version = 'HTTP/1.1' # TODO
        request_line = "%s %s %s\n" % (environ['REQUEST_METHOD'], path, request_version)

        class Dummy(object):
            pass

        # Let's pretend we have a server to hand to the handler.
        server = Dummy()
        server.server_name = environ['SERVER_NAME']
        server.server_port = int(environ['SERVER_PORT'])

        # Initialize the underlying handler and associated auth. provider.
        con = openerp.service.websrv_lib.noconnection(environ['wsgi.input'])
        handler = http_dir.instanciate_handler(con, environ['REMOTE_ADDR'], server)

        # Populate the handler as if it is called by a regular HTTP server
        # and the request is already parsed.
        handler.wfile = StringIO.StringIO()
        handler.rfile = environ['wsgi.input']
        handler.headers = headers
        handler.command = environ['REQUEST_METHOD']
        handler.path = path
        handler.request_version = request_version
        handler.close_connection = 1
        handler.raw_requestline = request_line
        handler.requestline = request_line

        # Handle authentication if there is an auth. provider associated to
        # the handler.
        if hasattr(handler, 'auth_provider'):
            try:
                handler.auth_provider.checkRequest(handler, path)
            except websrv_lib.AuthRequiredExc, ae:
                # Darwin 9.x.x webdav clients will report "HTTP/1.0" to us, while they support (and need) the
                # authorisation features of HTTP/1.1 
                if request_version != 'HTTP/1.1' and ('Darwin/9.' not in handler.headers.get('User-Agent', '')):
                    start_response("403 Forbidden", [])
                    return []
                start_response("401 Authorization required", [
                    ('WWW-Authenticate', '%s realm="%s"' % (ae.atype,ae.realm)),
                    # ('Connection', 'keep-alive'),
                    ('Content-Type', 'text/html'),
                    ('Content-Length', 4), # len(self.auth_required_msg)
                    ])
                return ['Blah'] # self.auth_required_msg
            except websrv_lib.AuthRejectedExc,e:
                start_response("403 %s" % (e.args[0],), [])
                return []

        method_name = 'do_' + handler.command

        # Support the OPTIONS method even when not provided directly by the
        # handler. TODO I would prefer to remove it and fix the handler if
        # needed.
        if not hasattr(handler, method_name):
            if handler.command == 'OPTIONS':
                return return_options(environ, start_response)
            start_response("501 Unsupported method (%r)" % handler.command, [])
            return []

        # Finally, call the handler's method.
        try:
            method = getattr(handler, method_name)
            method()
            # The DAV handler buffers its output and provides a _flush()
            # method.
            getattr(handler, '_flush', lambda: None)()
            response = parse_http_response(handler.wfile.getvalue())
            response_headers = response.getheaders()
            body = response.read()
            start_response(str(response.status) + ' ' + response.reason, response_headers)
            return [body]
        except (websrv_lib.AuthRejectedExc, websrv_lib.AuthRequiredExc):
            raise
        except Exception, e:
            start_response("500 Internal error", [])
            return []

    return wsgi_handler

def parse_http_response(s):
    """ Turn a HTTP response string into a httplib.HTTPResponse object."""
    class DummySocket(StringIO.StringIO):
        """
        This is used to provide a StringIO to httplib.HTTPResponse
        which, instead of taking a file object, expects a socket and
        uses its makefile() method.
        """
        def makefile(self, *args, **kw):
            return self
    response = httplib.HTTPResponse(DummySocket(s))
    response.begin()
    return response

# WSGI handlers registered through the register_wsgi_handler() function below.
module_handlers = []

def register_wsgi_handler(handler):
    """ Register a WSGI handler.

    Handlers are tried in the order they are added. We might provide a way to
    register a handler for specific routes later.
    """
    module_handlers.append(handler)

def application(environ, start_response):
    """ WSGI entry point."""

    # Try all handlers until one returns some result (i.e. not None).
    wsgi_handlers = [
        wsgi_xmlrpc_1,
        wsgi_xmlrpc,
        wsgi_jsonrpc,
        wsgi_xmlrpc_legacy,
        wsgi_webdav
        ] + module_handlers
    for handler in wsgi_handlers:
        result = handler(environ, start_response)
        if result is None:
            continue
        return result

    # We never returned from the loop.
    response = 'No handler found.\n'
    start_response('404 Not Found', [('Content-Type', 'text/plain'), ('Content-Length', str(len(response)))])
    return [response]

# The WSGI server, started by start_server(), stopped by stop_server().
httpd = None

def serve():
    """ Serve HTTP requests via werkzeug development server.

    If werkzeug can not be imported, we fall back to wsgiref's simple_server.

    Calling this function is blocking, you might want to call it in its own
    thread.
    """

    global httpd

    # TODO Change the xmlrpc_* options to http_*
    interface = config['xmlrpc_interface'] or '0.0.0.0'
    port = config['xmlrpc_port']
    try:
        import werkzeug.serving
        if config['proxy_mode']:
            from werkzeug.contrib.fixers import ProxyFix
            app = ProxyFix(application)
            suffix = ' (in proxy mode)'
        else:
            app = application
            suffix = ''
        httpd = werkzeug.serving.make_server(interface, port, app, threaded=True)
        _logger.info('HTTP service (werkzeug) running on %s:%s%s', interface, port, suffix)
    except ImportError:
        import wsgiref.simple_server
        _logger.warning('Werkzeug module unavailable, falling back to wsgiref.')
        if config['proxy_mode']:
            _logger.warning('Werkzeug module unavailable, not using proxy mode.')
        httpd = wsgiref.simple_server.make_server(interface, port, application)
        _logger.info('HTTP service (wsgiref) running on %s:%s', interface, port)

    httpd.serve_forever()

def start_server():
    """ Call serve() in its own thread.

    The WSGI server can be shutdown with stop_server() below.
    """
    threading.Thread(target=serve).start()

def stop_server():
    """ Initiate the shutdown of the WSGI server.

    The server is supposed to have been started by start_server() above.
    """
    if httpd:
        httpd.shutdown()

# Master process id, can be used for signaling.
arbiter_pid = None

# Application setup before we can spawn any worker process.
# This is suitable for e.g. gunicorn's on_starting hook.
def on_starting(server):
    global arbiter_pid
    arbiter_pid = os.getpid() # TODO check if this is true even after replacing the executable
    #openerp.tools.cache = kill_workers_cache
    openerp.netsvc.init_logger()
    openerp.osv.osv.start_object_proxy()
    openerp.service.web_services.start_web_services()
    openerp.modules.module.initialize_sys_path()
    openerp.modules.loading.open_openerp_namespace()
    for m in openerp.conf.server_wide_modules:
        try:
            openerp.modules.module.load_openerp_module(m)
        except Exception:
            msg = ''
            if m == 'web':
                msg = """
The `web` module is provided by the addons found in the `openerp-web` project.
Maybe you forgot to add those addons in your addons_path configuration."""
            _logger.exception('Failed to load server-wide module `%s`.%s', m, msg)

# Install our own signal handler on the master process.
def when_ready(server):
    # Hijack gunicorn's SIGWINCH handling; we can choose another one.
    signal.signal(signal.SIGWINCH, make_winch_handler(server))

# Install limits on virtual memory and CPU time consumption.
def pre_request(worker, req):
    import os
    import psutil
    import resource
    import signal
    # VMS and RLIMIT_AS are the same thing: virtual memory, a.k.a. address space
    rss, vms = psutil.Process(os.getpid()).get_memory_info()
    soft, hard = resource.getrlimit(resource.RLIMIT_AS)
    resource.setrlimit(resource.RLIMIT_AS, (config['virtual_memory_limit'], hard))

    r = resource.getrusage(resource.RUSAGE_SELF)
    cpu_time = r.ru_utime + r.ru_stime
    signal.signal(signal.SIGXCPU, time_expired)
    soft, hard = resource.getrlimit(resource.RLIMIT_CPU)
    resource.setrlimit(resource.RLIMIT_CPU, (cpu_time + config['cpu_time_limit'], hard))

# Reset the worker if it consumes too much memory (e.g. caused by a memory leak).
def post_request(worker, req, environ):
    import os
    import psutil
    rss, vms = psutil.Process(os.getpid()).get_memory_info()
    if vms > config['virtual_memory_reset']:
        _logger.info('Virtual memory consumption '
            'too high, rebooting the worker.')
        worker.alive = False # Commit suicide after the request.

# Our signal handler will signal a SGIQUIT to all workers.
def make_winch_handler(server):
    def handle_winch(sig, fram):
        server.kill_workers(signal.SIGQUIT) # This is gunicorn specific.
    return handle_winch

# SIGXCPU (exceeded CPU time) signal handler will raise an exception.
def time_expired(n, stack):
    _logger.info('CPU time limit exceeded.')
    raise Exception('CPU time limit exceeded.') # TODO one of openerp.exception

# Kill gracefuly the workers (e.g. because we want to clear their cache).
# This is done by signaling a SIGWINCH to the master process, so it can be
# called by the workers themselves.
def kill_workers():
    try:
        os.kill(arbiter_pid, signal.SIGWINCH)
    except OSError, e:
        if e.errno == errno.ESRCH: # no such pid
            return
        raise

class kill_workers_cache(openerp.tools.ormcache):
    def clear(self, dbname, *args, **kwargs):
        kill_workers()

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