source: fedd/remote_service.py @ a94cb0a

#!/usr/local/bin/python

import copy

import M2Crypto.httpslib
from M2Crypto.m2xmlrpclib import SSL_Transport
from ZSI import ParseException, FaultException, SoapWriter

from service_error import *
from xmlrpclib import ServerProxy, dumps, loads, Fault, Error, Binary

from fedd_util import fedd_ssl_context
from fedid import fedid


# Used by the remote_service_base class.
def to_binary(o):
    """
    A function that converts an object into an xmlrpclib.Binary using
    either its internal packing method, or the standard Binary constructor.
    """
    pack = getattr(o, 'pack_xmlrpc', None)
    if callable(pack): return Binary(pack())
    else: return Binary(o)

# Classes that encapsulate the process of making and dealing with requests to
# WSDL-generated and XMLRPC remote accesses.  

class remote_service_base:
    """
    This invisible base class encapsulates the functions used to massage the
    dictionaries used to pass parameters into and out of the RPC formats.  It's
    mostly a container for the static methods to do that work, but defines some
    maps sued by sub classes on apply_to_tags
    """
    # A map used to convert fedid fields to fedid objects (when the field is
    # already a string)
    fedid_to_object = ( ('fedid', lambda x: fedid(bits=x)),)
    # A map used by apply_to_tags to convert fedids from xmlrpclib.Binary
    # objects to fedid objects in one sweep.
    decap_fedids = (('fedid', lambda x: fedid(bits=x.data)),)
    # A map used to encapsulate fedids into xmlrpclib.Binary objects
    encap_fedids = (('fedid', to_binary),)

    @staticmethod
    def pack_soap(container, name, contents):
        """
        Convert the dictionary in contents into a tree of ZSI classes.

        The holder classes are constructed from factories in container and
        assigned to either the element or attribute name.  This is used to
        recursively create the SOAP message.
        """
        if getattr(contents, "__iter__", None) != None:
            attr =getattr(container, "new_%s" % name, None)
            if attr: obj = attr()
            else:
                raise TypeError("%s does not have a new_%s attribute" % \
                        (container, name))
            for e, v in contents.iteritems():
                assign = getattr(obj, "set_element_%s" % e, None) or \
                        getattr(obj, "set_attribute_%s" % e, None)
                if isinstance(v, type(dict())):
                    assign(remote_service_base.pack_soap(obj, e, v))
                elif getattr(v, "__iter__", None) != None:
                    assign([ remote_service_base.pack_soap(obj, e, val ) \
                            for val in v])
                elif getattr(v, "pack_soap", None) != None:
                    assign(v.pack_soap())
                else:
                    assign(v)
            return obj
        else: return contents

    @staticmethod
    def unpack_soap(element):
        """
        Convert a tree of ZSI SOAP classes intro a hash.  The inverse of
        pack_soap

        Elements or elements that are empty are ignored.
        """
        methods = [ m for m in dir(element) \
                if m.startswith("get_element") or m.startswith("get_attribute")]
        if len(methods) > 0:
            rv = { }
            for m in methods:
                if m.startswith("get_element_"):
                    n = m.replace("get_element_","",1)
                else:
                    n = m.replace("get_attribute_", "", 1)
                sub = getattr(element, m)()
                if sub != None:
                    if isinstance(sub, basestring):
                        rv[n] = sub
                    elif getattr(sub, "__iter__", None) != None:
                        if len(sub) > 0: rv[n] = \
                                [remote_service_base.unpack_soap(e) \
                                    for e in sub]
                    else:
                        rv[n] = remote_service_base.unpack_soap(sub)
            return rv
        else: 
            return element

    @staticmethod
    def apply_to_tags(e, map):
        """
        Map is an iterable of ordered pairs (tuples) that map a key to a
        function.
        This function walks the given message and replaces any object with a
        key in the map with the result of applying that function to the object.
        """
        if isinstance(e, dict):
            for k in e.keys():
                for tag, fcn in map:
                    if k == tag:
                        if isinstance(e[k], list):
                            e[k] = [ fcn(b) for b in e[k]]
                        else:
                            e[k] = fcn(e[k])
                    elif isinstance(e[k], dict):
                        remote_service_base.apply_to_tags(e[k], map)
                    elif isinstance(e[k], list):
                        for ee in e[k]:
                            remote_service_base.apply_to_tags(ee, map)
        # Other types end the recursion - they should be leaves
        return e

    @staticmethod
    def strip_unicode(obj):
        """Walk through a message and convert all strings to non-unicode
        strings"""
        if isinstance(obj, dict):
            for k in obj.keys():
                obj[k] = remote_service_base.strip_unicode(obj[k])
            return obj
        elif isinstance(obj, basestring) and not isinstance(obj, str):
            return str(obj)
        elif getattr(obj, "__iter__", None):
            return [ remote_service_base.strip_unicode(x) for x in obj]
        else:
            return obj

    @staticmethod
    def make_unicode(obj):
        """Walk through a message and convert all strings to unicode"""
        if isinstance(obj, dict):
            for k in obj.keys():
                obj[k] = remote_service_base.make_unicode(obj[k])
            return obj
        elif isinstance(obj, basestring) and not isinstance(obj, unicode):
            return unicode(obj)
        elif getattr(obj, "__iter__", None):
            return [ remote_service_base.make_unicode(x) for x in obj]
        else:
            return obj



class soap_handler(remote_service_base):
    """
    Encapsulate the handler code to unpack and pack SOAP requests and responses
    and call the given method.

    The code to decapsulate and encapsulate parameters encoded in SOAP is the
    same modulo a few parameters.  This is a functor that calls a fedd service
    trhough a soap interface.  The parameters are the typecode of the request
    parameters, the method to call (usually a bound instance of a method on a
    fedd service providing class), the constructor of a response packet and the
    name of the body element of that packet.  The handler takes a ParsedSoap
    object (the request) and returns an instance of the class created by
    constructor containing the response.  Failures of the constructor or badly
    created constructors will result in None being returned.
    """
    def __init__(self, typecode, method, constructor, body_name):
        self.typecode = typecode
        self.method = method
        self.constructor = constructor
        self.body_name = body_name

    def __call__(self, ps, fid):
        req = ps.Parse(self.typecode)
        # Convert the message to a dict with the fedid strings converted to
        # fedid objects
        req = self.apply_to_tags(self.unpack_soap(req), self.fedid_to_object)

        msg = self.method(req, fid)

        resp = self.constructor()
        set_element = getattr(resp, "set_element_%s" % self.body_name, None)
        if set_element and callable(set_element):
            try:
                set_element(self.pack_soap(resp, self.body_name, msg))
                return resp
            except (NameError, TypeError):
                return None
        else:
            return None

class xmlrpc_handler(remote_service_base):
    """
    Generate the handler code to unpack and pack XMLRPC requests and responses
    and call the given method.

    The code to marshall and unmarshall XMLRPC parameters to and from a fedd
    service is largely the same.  This helper creates such a handler.  The
    parameters are the method name, and the name of the body struct that
    contains the response.  A handler is created that takes the params response
    from an xmlrpclib.loads on the incoming rpc and a fedid and responds with
    a hash representing the struct ro be returned to the other side.  On error
    None is returned.  Fedid fields are decapsulated from binary and converted
    to fedid objects on input and encapsulated as Binaries on output.
    """
    def __init__(self, method, body_name):
        self.method = method
        self.body_name = body_name

    def __call__(self, params, fid):
        msg = None

        p = self.apply_to_tags(params[0], self.decap_fedids)
        try:
            msg = self.method(p, fid)
        except service_error, e:
            raise Fault(e.code_string(), e.desc)
        if msg != None:
            return self.make_unicode(self.apply_to_tags(\
                    { self.body_name: msg }, self.encap_fedids))
        else:
            return None

class service_caller(remote_service_base):
    def __init__(self, service_name, port_name, locator, request_message, 
            request_body_name, tracefile=None):
        self.service_name = service_name
        self.port_name = port_name
        self.locator = locator
        self.request_message = request_message
        self.request_body_name = request_body_name
        self.tracefile = tracefile
        self.__call__ = self.call_service

    def serialize_soap(self, req):
        """
        Return a string containing the message that would be sent to call this
        service with the given request.
        """
        msg = self.request_message()
        set_element = getattr(msg, "set_element_%s" % self.request_body_name,
                None)
        if not set_element:
            raise service_error(service_error.internal,
                    "Cannot get element setting method for %s" % \
                            self.request_body_name)
        set_element(self.pack_soap(msg, self.request_body_name, req))
        sw = SoapWriter()
        sw.serialize(msg)
        return unicode(sw)

    def call_xmlrpc_service(self, url, req, cert_file=None, cert_pwd=None, 
            trusted_certs=None, context=None, tracefile=None):
        """Send an XMLRPC request.  """


        # If a context is given, use it.  Otherwise construct one from
        # components.  The construction shouldn't call out for passwords.
        if context:
            ctx = context
        else:
            try:
                ctx = fedd_ssl_context(cert_file, trusted_certs, 
                        password=cert_pwd)
            except SSL.SSLError:
                raise service_error(service_error.server_config,
                        "Certificates misconfigured")

        # Of all the dumbass things.  The XMLRPC library in use here won't
        # properly encode unicode strings, so we make a copy of req with
        # the unicode objects converted.  We also convert the url to a
        # basic string if it isn't one already.
        r = self.strip_unicode(copy.deepcopy(req))
        url = str(url)
        
        transport = SSL_Transport(ctx)
        port = ServerProxy(url, transport=transport)
        # Make the call, and convert faults back to service_errors
        try:
            remote_method = getattr(port, self.service_name, None)
            resp = remote_method(self.apply_to_tags(\
                    { self.request_body_name: r}, self.encap_fedids))
        except Fault, f:
            raise service_error(None, f.faultString, f.faultCode)
        except Error, e:
            raise service_error(service_error.protocol, 
                    "Remote XMLRPC Fault: %s" % e)

        return self.apply_to_tags(resp, self.decap_fedids) 

    def call_soap_service(self, url, req, cert_file=None, cert_pwd=None,
            trusted_certs=None, context=None, tracefile=None):
        """
        Send req on to the real destination in dt and return the response

        Req is just the requestType object.  This function re-wraps it.  It
        also rethrows any faults.
        """

        tf = tracefile or self.tracefile or None

        # If a context is given, use it.  Otherwise construct one from
        # components.  The construction shouldn't call out for passwords.
        if context:
            ctx = context
        else:
            try:
                ctx = fedd_ssl_context(cert_file, trusted_certs, 
                        password=cert_pwd)
            except SSL.SSLError:
                raise service_error(service_error.server_config,
                        "Certificates misconfigured")
        loc = self.locator()
        get_port = getattr(loc, self.port_name, None)
        if not get_port:
            raise service_error(service_error.internal, 
                    "Cannot get port %s from locator" % self.port_name)
        port = get_port(url,
                transport=M2Crypto.httpslib.HTTPSConnection, 
                transdict={ 'ssl_context' : ctx },
                tracefile=tf)
        remote_method = getattr(port, self.service_name, None)
        if not remote_method:
            raise service_error(service_error.internal,
                    "Cannot get service from SOAP port")

        # Reconstruct the full request message
        msg = self.request_message()
        set_element = getattr(msg, "set_element_%s" % self.request_body_name,
                None)
        if not set_element:
            raise service_error(service_error.internal,
                    "Cannot get element setting method for %s" % \
                            self.request_body_name)
        set_element(self.pack_soap(msg, self.request_body_name, req))
        try:
            resp = remote_method(msg)
        except ParseException, e:
            raise service_error(service_error.protocol,
                    "Bad format message (XMLRPC??): %s" % e)
        except FaultException, e:
            ee = self.unpack_soap(e.fault.detail[0]).get('FeddFaultBody', { })
            if ee:
                raise service_error(ee['code'], ee['desc'])
            else:
                raise service_error(service_error.internal,
                        "Unexpected fault body")
        # Unpack and convert fedids to objects
        r = self.apply_to_tags(self.unpack_soap(resp), self.fedid_to_object)
        #  Make sure all strings are unicode
        r = self.make_unicode(r)
        return r

    def call_service(self, url, req, cert_file=None, cert_pwd=None, 
        trusted_certs=None, context=None, tracefile=None):
        p_fault = None  # Any SOAP failure (sent unless XMLRPC works)
        resp = None
        try:
            # Try the SOAP request
            resp = self.call_soap_service(url, req, 
                    cert_file, cert_pwd, trusted_certs, context, tracefile)
            return resp
        except service_error, e:
            if e.code == service_error.protocol: p_fault = None
            else: raise
        except FaultException, f:
            p_fault = f.fault.detail[0]
                

        # If we could not get a valid SOAP response to the request above,
        # try the same address using XMLRPC and let any faults flow back
        # out.
        if p_fault == None:
            resp = self.call_xmlrpc_service(url, req, cert_file,
                    cert_pwd, trusted_certs, context, tracefile)
            return resp
        else:
            # Build the fault
            ee = unpack_soap(p_fault).get('FeddFaultBody', { })
            if ee:
                raise service_error(ee['code'], ee['desc'])
            else:
                raise service_error(service_error.internal,
                        "Unexpected fault body")