'''Cobalt component base classes'''
__revision__ = '$Revision$'

import atexit, logging, select, signal, socket, sys, time, urlparse, xmlrpclib, cPickle, ConfigParser, os
from base64 import decodestring

import BaseHTTPServer, SimpleXMLRPCServer
import Bcfg2.tlslite.errors
import Bcfg2.tlslite.api

import Bcfg2.Client.Proxy as Proxy
from Bcfg2.tlslite.TLSConnection import TLSConnection

from Bcfg2.Settings import settings

log = logging.getLogger('Component')

class ComponentInitError(Exception):
    '''Raised in case of component initialization failure'''
    pass

class ComponentKeyError(Exception):
    '''raised in case of key parse fails'''
    pass

class ForkedChild(Exception):
    '''raised after child has been forked'''
    pass

class CobaltXMLRPCRequestHandler(SimpleXMLRPCServer.SimpleXMLRPCRequestHandler):
    '''CobaltXMLRPCRequestHandler takes care of ssl xmlrpc requests'''

    def do_POST(self):
        '''Overload do_POST to pass through client address information'''
        try:
            self.cleanup = True
            # get arguments
            data = self.rfile.read(int(self.headers["content-length"]))

            authenticated = False
            #try x509 cert auth (will have been completed, just checking status)
            authenticated = self.request.authenticated
            #TLSConnection can be accessed by self.request?
            
            #try httpauth
            if not authenticated and "Authorization" in self.headers:
                #need more checking here in case its all garbled
                namepass = decodestring(self.headers["Authorization"].strip("Basic ")).split(":")
                if self.server._authenticate_connection("bogus-method",
                                                        namepass[0],
                                                        namepass[1],
                                                        self.client_address):
                    authenticated = True

            response = self.server._cobalt_marshalled_dispatch(data, self.client_address, authenticated)
        except ForkedChild:
            self.cleanup = False
            return
        except: # This should only happen if the module is buggy
            # internal error, report as HTTP server error
            log.error("Unexcepted handler failure in do_POST", exc_info=1)
            self.send_response(500)
            self.end_headers()
        else:
            # got a valid XML RPC response
            try:
                self.send_response(200)
                self.send_header("Content-type", "text/xml")
                self.send_header("Content-length", str(len(response)))
                self.end_headers()
                self.wfile.write(response)
                
                # shut down the connection
                self.wfile.flush()
                #self.connection.shutdown()
            except socket.error:
                pass

    def setup(self):
        '''Setup a working connection'''
        self.connection = self.request
        self.rfile = socket._fileobject(self.request, "rb", self.rbufsize)
        self.wfile = socket._fileobject(self.request, "wb", self.wbufsize)

class TLSServer(Bcfg2.tlslite.api.TLSSocketServerMixIn,
                BaseHTTPServer.HTTPServer):
    '''This class is an tlslite-using SSLServer'''
    def __init__(self, address, keyfile, handler, checker=None,
                 reqCert=False):
        self.sc = Bcfg2.tlslite.api.SessionCache()
        self.rc = reqCert
        self.master = os.getpid()
        x509 = Bcfg2.tlslite.api.X509()
        s = open(keyfile).read()
        x509.parse(s)
        self.checker = checker
        try:
            self.key = Bcfg2.tlslite.api.parsePEMKey(s, private=True)
        except:
            raise ComponentKeyError
        self.chain = Bcfg2.tlslite.api.X509CertChain([x509])
        BaseHTTPServer.HTTPServer.__init__(self, address, handler)

    def finish_request(self, sock, address):
        sock.settimeout(90)
        tlsConnection = TLSConnection(sock)
        if self.handshake(tlsConnection) == True:
            req = self.RequestHandlerClass(tlsConnection, address, self)
            if req.cleanup:
                tlsConnection.close()
            if os.getpid() != self.master:
                os._exit(0)

    def handshake(self, tlsConnection):
        try:
            tlsConnection.handshakeServer(certChain=self.chain,
                                          privateKey=self.key,
                                          sessionCache=self.sc,
                                          checker=self.checker,
                                          reqCert=self.rc)
            tlsConnection.ignoreAbruptClose = True
            #Connection authenticated during TLS handshake, no need for passwords
            if not self.checker == None:
                tlsConnection.authenticated = True
            else:
                tlsConnection.authenticated = False
            return True
        except Bcfg2.tlslite.errors.TLSError, error:
            return False
        except socket.error:
            return False
                
class Component(TLSServer,
                SimpleXMLRPCServer.SimpleXMLRPCDispatcher):
    """Cobalt component providing XML-RPC access"""
    __name__ = 'Component'
    __implementation__ = 'Generic'
    __statefields__ = []
    async_funcs = ['assert_location']
    fork_funcs = []
    child_limit = 32

    def __init__(self, setup):
        # need to get addr
        self.setup = setup
        self.shut = False
        signal.signal(signal.SIGINT, self.start_shutdown)
        signal.signal(signal.SIGTERM, self.start_shutdown)
        self.logger = logging.getLogger('Component')
        self.children = []
        self.static = True

        location = settings.COMPONENTS_BCFG2
        if settings.COMPONENTS_BCFG2_STATIC:
            location = urlparse.urlparse(settings.COMPONENTS_BCFG2)[1].split(':')
            location = (location[0], int(location[1]))

        if not settings.COMMUNICATION_KEY:
            print "No key specified in '%s'" % settings.CONFIG_FILE
            raise SystemExit, 1
        keyfile = settings.COMMUNICATION_KEY

        self.password = settings.COMMUNICATION_PASSWORD

        try:
            TLSServer.__init__(self, location, keyfile, CobaltXMLRPCRequestHandler)
        except socket.error:
            self.logger.error("Failed to bind to socket")
            raise ComponentInitError
        except ComponentKeyError:
            self.logger.error("Failed to parse key" % (keyfile))
            raise ComponentInitError
        except:
            self.logger.error("Failed to load ssl key '%s'" % (keyfile), exc_info=1)
            raise ComponentInitError
        try:
            SimpleXMLRPCServer.SimpleXMLRPCDispatcher.__init__(self)
        except TypeError:
            SimpleXMLRPCServer.SimpleXMLRPCDispatcher.__init__(self, False, None)
        self.logRequests = 0
        self.port = self.socket.getsockname()[1]
        self.url = "https://%s:%s" % (socket.gethostname(), self.port)
        self.logger.info("Bound to port %s" % self.port)
        self.funcs.update({'system.listMethods':self.addr_system_listMethods})
        self.atime = 0
        self.assert_location()
        atexit.register(self.deassert_location)

    def _cobalt_marshalled_dispatch(self, data, address, authenticated=False):
        """Decode and dispatch XMLRPC requests. Overloaded to pass through
        client address information
        """
        try:
            rawparams, method = xmlrpclib.loads(data)
        except:
            self.logger.error("Failed to parse request from %s" \
                              % (address[0]))
            #open('/tmp/badreq', 'w').write(data)
            return xmlrpclib.dumps(xmlrpclib.Fault(4, "Bad Request"))
        if not authenticated:
            if len(rawparams) < 2:
                self.logger.error("No authentication included with request from %s" % address[0])
                return xmlrpclib.dumps(xmlrpclib.Fault(2, "No Authentication Info"))
            user = rawparams[0]
            password = rawparams[1]
            params = rawparams[2:]
            # check authentication
            if not self._authenticate_connection(method, user, password, address):
                return xmlrpclib.dumps(xmlrpclib.Fault(3, "Authentication Failure"))
        else:
            #there is no prefixed auth info in this case
            params = rawparams[0:]
        # generate response
        try:
            # need to add waitpid code here to enforce maxchild
            if method in self.fork_funcs:
                self.clean_up_children()
                pid = os.fork()
                if pid:
                    self.children.append(pid)
                    raise ForkedChild
            # all handlers must take address as the first argument
            response = self._dispatch(method, (address, ) + params)
            # wrap response in a singleton tuple
            response = (response,)
            response = xmlrpclib.dumps(response, methodresponse=1)
        except xmlrpclib.Fault, fault:
            response = xmlrpclib.dumps(fault)
        except TypeError, terror:
            self.logger.error("Client %s called function %s with wrong argument count" %
                           (address[0], method), exc_info=1)
            response = xmlrpclib.dumps(xmlrpclib.Fault(4, terror.args[0]))
        except ForkedChild:
            raise
        except:
            self.logger.error("Unexpected handler failure", exc_info=1)
            # report exception back to server
            response = xmlrpclib.dumps(xmlrpclib.Fault(1,
                                   "%s:%s" % (sys.exc_type, sys.exc_value)))
        return response

    def clean_up_children(self):
        while True:
            try:
                pid = os.waitpid(0, os.WNOHANG)[0]
                if pid:
                    self.logger.debug("process %d exited" % pid)
                    if pid in self.children:
                        self.children.remove(pid)
                else:
                    break
            except OSError:
                break
        if len(self.children) >= self.child_limit:
            self.logger.info("Reached child_limit; waiting for child exit")
            pid = os.waitpid(0, 0)[0]
            self.children.remove(pid)
            self.logger.debug("process %d exited" % pid)

    def _authenticate_connection(self, method, user, password, address):
        '''Authenticate new connection'''
        (user, address, method)
        return password == self.password

    def save_state(self):
        '''Save fields defined in __statefields__ in /var/spool/cobalt/__implementation__'''
        if self.__statefields__:
            savedata = tuple([getattr(self, field) for field in self.__statefields__])
        try:
            statefile = open("/var/spool/cobalt/%s" % self.__implementation__, 'w')
            # need to flock here
            statefile.write(cPickle.dumps(savedata))
        except:
            self.logger.info("Statefile save failed; data persistence disabled")
            self.__statefields__ = []

    def load_state(self):
        '''Load fields defined in __statefields__ from /var/spool/cobalt/__implementation__'''
        if self.__statefields__:
            try:
                loaddata = cPickle.loads(open("/var/spool/cobalt/%s" % self.__implementation__).read())
            except:
                self.logger.info("Statefile load failed")
                return
            for field in self.__statefields__:
                setattr(self, field, loaddata[self.__statefields__.index(field)])
                
    def addr_system_listMethods(self, address):
        """get rid of the address argument and call the underlying dispatcher method"""
        return SimpleXMLRPCServer.SimpleXMLRPCDispatcher.system_listMethods(self)

    def get_request(self):
        '''We need to do work between requests, so select with timeout instead of blocking in accept'''
        rsockinfo = []
        while self.socket not in rsockinfo:
            if self.shut:
                raise socket.error
            for funcname in self.async_funcs:
                func = getattr(self, funcname, False)
                if callable(func):
                    func()
                else:
                    self.logger.error("Cannot call uncallable method %s" % (funcname))
            try:
                rsockinfo = select.select([self.socket], [], [], 10)[0]
            except select.error:
                continue
            if self.socket in rsockinfo:
                return self.socket.accept()

    def assert_location(self):
        '''Assert component location with slp'''
        if self.__name__ == 'service-location' or self.static:
            return
        if (time.time() - self.atime) > 240:
            slp = Proxy.service_location()
            slp.AssertService({'tag':'location', 'name':self.__name__, 'url':self.url})
            self.atime = time.time()

    def deassert_location(self):
        '''remove registration from slp'''
        if self.__name__ == 'service-location' or self.static:
            return
        slp = Proxy.service_location()
        try:
            slp.DeassertService([{'tag':'location', 'name':self.__name__, 'url':self.url}])
        except xmlrpclib.Fault, fault:
            if fault.faultCode == 11:
                self.logger.error("Failed to deregister self; no matching component")

    def serve_forever(self):
        """Handle one request at a time until doomsday."""
        while not self.shut:
            self.handle_request()

    def start_shutdown(self, signum, frame):
        '''Shutdown on unexpected signals'''
        self.shut = True