00001 """
00002 XML utilities.
00003
00004 $Id: xml_utils.py 2493 2009-06-04 18:30:40Z sra $
00005
00006 Copyright (C) 2009 Internet Systems Consortium ("ISC")
00007
00008 Permission to use, copy, modify, and distribute this software for any
00009 purpose with or without fee is hereby granted, provided that the above
00010 copyright notice and this permission notice appear in all copies.
00011
00012 THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
00013 REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
00014 AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
00015 INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
00016 LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
00017 OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
00018 PERFORMANCE OF THIS SOFTWARE.
00019
00020 Portions copyright (C) 2007--2008 American Registry for Internet Numbers ("ARIN")
00021
00022 Permission to use, copy, modify, and distribute this software for any
00023 purpose with or without fee is hereby granted, provided that the above
00024 copyright notice and this permission notice appear in all copies.
00025
00026 THE SOFTWARE IS PROVIDED "AS IS" AND ARIN DISCLAIMS ALL WARRANTIES WITH
00027 REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
00028 AND FITNESS. IN NO EVENT SHALL ARIN BE LIABLE FOR ANY SPECIAL, DIRECT,
00029 INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
00030 LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
00031 OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
00032 PERFORMANCE OF THIS SOFTWARE.
00033 """
00034
00035 import xml.sax, lxml.sax, lxml.etree, base64
00036 import rpki.exceptions
00037
00038 class sax_handler(xml.sax.handler.ContentHandler):
00039 """
00040 SAX handler for RPKI protocols.
00041
00042 This class provides some basic amenities for parsing protocol XML of
00043 the kind we use in the RPKI protocols, including whacking all the
00044 protocol element text into US-ASCII, simplifying accumulation of
00045 text fields, and hiding some of the fun relating to XML namespaces.
00046
00047 General assumption: by the time this parsing code gets invoked, the
00048 XML has already passed RelaxNG validation, so we only have to check
00049 for errors that the schema can't catch, and we don't have to play as
00050 many XML namespace games.
00051 """
00052
00053 def __init__(self):
00054 """
00055 Initialize SAX handler.
00056 """
00057 xml.sax.handler.ContentHandler.__init__(self)
00058 self.text = ""
00059 self.stack = []
00060
00061 def startElementNS(self, name, qname, attrs):
00062 """Redirect startElementNS() events to startElement()."""
00063 return self.startElement(name[1], attrs)
00064
00065 def endElementNS(self, name, qname):
00066 """Redirect endElementNS() events to endElement()."""
00067 return self.endElement(name[1])
00068
00069 def characters(self, content):
00070 """Accumulate a chuck of element content (text)."""
00071 self.text += content
00072
00073 def startElement(self, name, attrs):
00074 """
00075 Handle startElement() events.
00076
00077 We maintain a stack of nested elements under construction so that
00078 we can feed events directly to the current element rather than
00079 having to pass them through all the nesting elements.
00080
00081 If the stack is empty, this event is for the outermost element, so
00082 we call a virtual method to create the corresponding object and
00083 that's the object we'll be returning as our final result.
00084 """
00085
00086 a = dict()
00087 for k, v in attrs.items():
00088 if isinstance(k, tuple):
00089 if k == ("http://www.w3.org/XML/1998/namespace", "lang"):
00090 k = "xml:lang"
00091 else:
00092 assert k[0] is None
00093 k = k[1]
00094 a[k.encode("ascii")] = v.encode("ascii")
00095 if len(self.stack) == 0:
00096 assert not hasattr(self, "result")
00097 self.result = self.create_top_level(name, a)
00098 self.stack.append(self.result)
00099 self.stack[-1].startElement(self.stack, name, a)
00100
00101 def endElement(self, name):
00102 """
00103 Handle endElement() events. Mostly this means handling any
00104 accumulated element text.
00105 """
00106 text = self.text.encode("ascii").strip()
00107 self.text = ""
00108 self.stack[-1].endElement(self.stack, name, text)
00109
00110 @classmethod
00111 def saxify(cls, elt):
00112 """
00113 Create a one-off SAX parser, parse an ETree, return the result.
00114 """
00115 self = cls()
00116 lxml.sax.saxify(elt, self)
00117 return self.result
00118
00119 def create_top_level(self, name, attrs):
00120 """
00121 Handle top-level PDU for this protocol.
00122 """
00123 assert name == self.name and attrs["version"] == self.version
00124 return self.pdu()
00125
00126 class base_elt(object):
00127 """
00128 Virtual base class for XML message elements. The left-right and
00129 publication protocols use this. At least for now, the up-down
00130 protocol does not, due to different design assumptions.
00131 """
00132
00133
00134
00135 attributes = ()
00136
00137
00138
00139 elements = ()
00140
00141
00142
00143 booleans = ()
00144
00145 def startElement(self, stack, name, attrs):
00146 """
00147 Default startElement() handler: just process attributes.
00148 """
00149 if name not in self.elements:
00150 assert name == self.element_name, "Unexpected name %s, stack %s" % (name, stack)
00151 self.read_attrs(attrs)
00152
00153 def endElement(self, stack, name, text):
00154 """
00155 Default endElement() handler: just pop the stack.
00156 """
00157 assert name == self.element_name, "Unexpected name %s, stack %s" % (name, stack)
00158 stack.pop()
00159
00160 def toXML(self):
00161 """
00162 Default toXML() element generator.
00163 """
00164 return self.make_elt()
00165
00166 def read_attrs(self, attrs):
00167 """
00168 Template-driven attribute reader.
00169 """
00170 for key in self.attributes:
00171 val = attrs.get(key, None)
00172 if isinstance(val, str) and val.isdigit():
00173 val = long(val)
00174 setattr(self, key, val)
00175 for key in self.booleans:
00176 setattr(self, key, attrs.get(key, False))
00177
00178 def make_elt(self):
00179 """
00180 XML element constructor.
00181 """
00182 elt = lxml.etree.Element("{%s}%s" % (self.xmlns, self.element_name), nsmap = self.nsmap)
00183 for key in self.attributes:
00184 val = getattr(self, key, None)
00185 if val is not None:
00186 elt.set(key, str(val))
00187 for key in self.booleans:
00188 if getattr(self, key, False):
00189 elt.set(key, "yes")
00190 return elt
00191
00192 def make_b64elt(self, elt, name, value = None):
00193 """
00194 Constructor for Base64-encoded subelement.
00195 """
00196 if value is None:
00197 value = getattr(self, name, None)
00198 if value is not None:
00199 lxml.etree.SubElement(elt, "{%s}%s" % (self.xmlns, name), nsmap = self.nsmap).text = base64.b64encode(value)
00200
00201 def __str__(self):
00202 """
00203 Convert a base_elt object to string format.
00204 """
00205 lxml.etree.tostring(self.toXML(), pretty_print = True, encoding = "us-ascii")
00206
00207 @classmethod
00208 def make_pdu(cls, **kargs):
00209 """
00210 Generic PDU constructor.
00211 """
00212 self = cls()
00213 for k, v in kargs.items():
00214 if isinstance(v, bool):
00215 v = 1 if v else 0
00216 setattr(self, k, v)
00217 return self
00218
00219 class data_elt(base_elt):
00220 """
00221 Virtual base class for PDUs that map to SQL objects. These objects
00222 all implement the create/set/get/list/destroy action attribute.
00223 """
00224
00225 def endElement(self, stack, name, text):
00226 """
00227 Default endElement handler for SQL-based objects. This assumes
00228 that sub-elements are Base64-encoded using the sql_template
00229 mechanism.
00230 """
00231 if name in self.elements:
00232 elt_type = self.sql_template.map.get(name)
00233 assert elt_type is not None, "Couldn't find element type for %s, stack %s" % (name, stack)
00234 setattr(self, name, elt_type(Base64 = text))
00235 else:
00236 assert name == self.element_name, "Unexpected name %s, stack %s" % (name, stack)
00237 stack.pop()
00238
00239 def toXML(self):
00240 """
00241 Default element generator for SQL-based objects. This assumes
00242 that sub-elements are Base64-encoded DER objects.
00243 """
00244 elt = self.make_elt()
00245 for i in self.elements:
00246 x = getattr(self, i, None)
00247 if x and not x.empty():
00248 self.make_b64elt(elt, i, x.get_DER())
00249 return elt
00250
00251 def make_reply(self, r_pdu = None):
00252 """
00253 Construct a reply PDU.
00254 """
00255 if r_pdu is None:
00256 r_pdu = self.__class__()
00257 self.make_reply_clone_hook(r_pdu)
00258 handle_name = self.element_name + "_handle"
00259 setattr(r_pdu, handle_name, getattr(self, handle_name, None))
00260 else:
00261 for b in r_pdu.booleans:
00262 setattr(r_pdu, b, False)
00263 r_pdu.action = self.action
00264 r_pdu.tag = self.tag
00265 return r_pdu
00266
00267 def make_reply_clone_hook(self, r_pdu):
00268 """Overridable hook."""
00269 pass
00270
00271 def serve_fetch_one(self):
00272 """
00273 Find the object on which a get, set, or destroy method should
00274 operate.
00275 """
00276 r = self.serve_fetch_one_maybe()
00277 if r is None:
00278 raise rpki.exceptions.NotFound
00279 return r
00280
00281 def serve_pre_save_hook(self, q_pdu, r_pdu, cb, eb):
00282 """Overridable hook."""
00283 cb()
00284
00285 def serve_post_save_hook(self, q_pdu, r_pdu, cb, eb):
00286 """Overridable hook."""
00287 cb()
00288
00289 def serve_create(self, r_msg, cb, eb):
00290 """
00291 Handle a create action.
00292 """
00293
00294 r_pdu = self.make_reply()
00295
00296 def one():
00297 self.sql_store()
00298 setattr(r_pdu, self.sql_template.index, getattr(self, self.sql_template.index))
00299 self.serve_post_save_hook(self, r_pdu, two, eb)
00300
00301 def two():
00302 r_msg.append(r_pdu)
00303 cb()
00304
00305 if self.serve_fetch_one_maybe() is not None:
00306 raise rpki.exceptions.DuplicateObject
00307
00308 self.serve_pre_save_hook(self, r_pdu, one, eb)
00309
00310 def serve_set(self, r_msg, cb, eb):
00311 """
00312 Handle a set action.
00313 """
00314
00315 db_pdu = self.serve_fetch_one()
00316 r_pdu = self.make_reply()
00317 for a in db_pdu.sql_template.columns[1:]:
00318 v = getattr(self, a)
00319 if v is not None:
00320 setattr(db_pdu, a, v)
00321 db_pdu.sql_mark_dirty()
00322
00323 def one():
00324 db_pdu.sql_store()
00325 db_pdu.serve_post_save_hook(self, r_pdu, two, eb)
00326
00327 def two():
00328 r_msg.append(r_pdu)
00329 cb()
00330
00331 db_pdu.serve_pre_save_hook(self, r_pdu, one, eb)
00332
00333 def serve_get(self, r_msg, cb, eb):
00334 """
00335 Handle a get action.
00336 """
00337 r_pdu = self.serve_fetch_one()
00338 self.make_reply(r_pdu)
00339 r_msg.append(r_pdu)
00340 cb()
00341
00342 def serve_list(self, r_msg, cb, eb):
00343 """
00344 Handle a list action for non-self objects.
00345 """
00346 for r_pdu in self.serve_fetch_all():
00347 self.make_reply(r_pdu)
00348 r_msg.append(r_pdu)
00349 cb()
00350
00351 def serve_destroy(self, r_msg, cb, eb):
00352 """
00353 Handle a destroy action.
00354 """
00355 db_pdu = self.serve_fetch_one()
00356 db_pdu.sql_delete()
00357 r_msg.append(self.make_reply())
00358 cb()
00359
00360 def serve_dispatch(self, r_msg, cb, eb):
00361 """
00362 Action dispatch handler.
00363 """
00364 dispatch = { "create" : self.serve_create,
00365 "set" : self.serve_set,
00366 "get" : self.serve_get,
00367 "list" : self.serve_list,
00368 "destroy" : self.serve_destroy }
00369 if self.action not in dispatch:
00370 raise rpki.exceptions.BadQuery, "Unexpected query: action %s" % self.action
00371 dispatch[self.action](r_msg, cb, eb)
00372
00373 def unimplemented_control(self, *controls):
00374 """
00375 Uniform handling for unimplemented control operations.
00376 """
00377 unimplemented = [x for x in controls if getattr(self, x, False)]
00378 if unimplemented:
00379 raise rpki.exceptions.NotImplementedYet, "Unimplemented control %s" % ", ".join(unimplemented)
00380
00381 class msg(list):
00382 """
00383 Generic top-level PDU.
00384 """
00385
00386 def startElement(self, stack, name, attrs):
00387 """
00388 Handle top-level PDU.
00389 """
00390 if name == "msg":
00391 assert self.version == int(attrs["version"])
00392 self.type = attrs["type"]
00393 else:
00394 elt = self.pdus[name]()
00395 self.append(elt)
00396 stack.append(elt)
00397 elt.startElement(stack, name, attrs)
00398
00399 def endElement(self, stack, name, text):
00400 """
00401 Handle top-level PDU.
00402 """
00403 assert name == "msg", "Unexpected name %s, stack %s" % (name, stack)
00404 assert len(stack) == 1
00405 stack.pop()
00406
00407 def __str__(self):
00408 """Convert msg object to string."""
00409 lxml.etree.tostring(self.toXML(), pretty_print = True, encoding = "us-ascii")
00410
00411 def toXML(self):
00412 """
00413 Generate top-level PDU.
00414 """
00415 elt = lxml.etree.Element("{%s}msg" % (self.xmlns), nsmap = self.nsmap, version = str(self.version), type = self.type)
00416 elt.extend([i.toXML() for i in self])
00417 return elt