Checkpoint. Refactor to avoid circular module dependency.

svn path=/rpkid/rpki/left_right.py; revision=1831

1 files changed, 278 insertions, 0 deletions

diff --git a/rpkid/rpki/xml_utils.py b/rpkid/rpki/xml_utils.py
new file mode 100644
index 00000000..9a2f6f61
--- /dev/null
+++ b/rpkid/rpki/xml_utils.py
@@ -0,0 +1,278 @@
+# $Id$
+
+# Copyright (C) 2007--2008  American Registry for Internet Numbers ("ARIN")
+#
+# Permission to use, copy, modify, and distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND ARIN DISCLAIMS ALL WARRANTIES WITH
+# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+# AND FITNESS.  IN NO EVENT SHALL ARIN BE LIABLE FOR ANY SPECIAL, DIRECT,
+# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+# OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+# PERFORMANCE OF THIS SOFTWARE.
+
+"""XML utilities."""
+
+import xml.sax, lxml.sax, lxml.etree, base64
+
+class sax_handler(xml.sax.handler.ContentHandler):
+  """SAX handler for RPKI protocols.
+
+  This class provides some basic amenities for parsing protocol XML of
+  the kind we use in the RPKI protocols, including whacking all the
+  protocol element text into US-ASCII, simplifying accumulation of
+  text fields, and hiding some of the fun relating to XML namespaces.
+
+  General assumption: by the time this parsing code gets invoked, the
+  XML has already passed RelaxNG validation, so we only have to check
+  for errors that the schema can't catch, and we don't have to play as
+  many XML namespace games.
+  """
+
+  def __init__(self):
+    """Initialize SAX handler."""
+    self.text = ""
+    self.stack = []
+
+  def startElementNS(self, name, qname, attrs):
+    """Redirect startElementNS() events to startElement()."""
+    return self.startElement(name[1], attrs)
+
+  def endElementNS(self, name, qname):
+    """Redirect endElementNS() events to endElement()."""
+    return self.endElement(name[1])
+
+  def characters(self, content):
+    """Accumulate a chuck of element content (text)."""
+    self.text += content
+
+  def startElement(self, name, attrs):
+    """Handle startElement() events.
+
+    We maintain a stack of nested elements under construction so that
+    we can feed events directly to the current element rather than
+    having to pass them through all the nesting elements.
+
+    If the stack is empty, this event is for the outermost element, so
+    we call a virtual method to create the corresponding object and
+    that's the object we'll be returning as our final result.
+    """
+    a = dict()
+    for k,v in attrs.items():
+      if isinstance(k, tuple):
+        if k == ("http://www.w3.org/XML/1998/namespace", "lang"):
+          k = "xml:lang"
+        else:
+          assert k[0] is None
+          k = k[1]
+      a[k.encode("ascii")] = v.encode("ascii")
+    if len(self.stack) == 0:
+      assert not hasattr(self, "result")
+      self.result = self.create_top_level(name, a)
+      self.stack.append(self.result)
+    self.stack[-1].startElement(self.stack, name, a)
+
+  def endElement(self, name):
+    """Handle endElement() events.
+
+    Mostly this means handling any accumulated element text.
+    """
+    text = self.text.encode("ascii").strip()
+    self.text = ""
+    self.stack[-1].endElement(self.stack, name, text)
+
+  @classmethod
+  def saxify(cls, elt):
+    """Create a one-off SAX parser, parse an ETree, return the result.
+    """
+    self = cls()
+    lxml.sax.saxify(elt, self)
+    return self.result
+
+  def create_top_level(self, name, attrs):
+    """Handle top-level PDU for this protocol."""
+    assert name == self.name and attrs["version"] == self.version
+    return self.pdu()
+
+class base_elt(object):
+  """Virtual base class for XML message elements.  The left-right and
+  publication protocols use this.  At least for now, the up-down
+  protocol does not, due to different design assumptions.
+  """
+
+  attributes = ()
+  elements = ()
+  booleans = ()
+
+  def startElement(self, stack, name, attrs):
+    """Default startElement() handler: just process attributes."""
+    self.read_attrs(attrs)
+
+  def endElement(self, stack, name, text):
+    """Default endElement() handler: just pop the stack."""
+    stack.pop()
+
+  def read_attrs(self, attrs):
+    """Template-driven attribute reader."""
+    for key in self.attributes:
+      val = attrs.get(key, None)
+      if isinstance(val, str) and val.isdigit():
+        val = long(val)
+      setattr(self, key, val)
+    for key in self.booleans:
+      setattr(self, key, attrs.get(key, False))
+
+  def make_elt(self):
+    """XML element constructor."""
+    elt = lxml.etree.Element("{%s}%s" % (self.xmlns, self.element_name), nsmap = self.nsmap)
+    for key in self.attributes:
+      val = getattr(self, key, None)
+      if val is not None:
+        elt.set(key, str(val))
+    for key in self.booleans:
+      if getattr(self, key, False):
+        elt.set(key, "yes")
+    return elt
+
+  def make_b64elt(self, elt, name, value = None):
+    """Constructor for Base64-encoded subelement."""
+    if value is None:
+      value = getattr(self, name, None)
+    if value is not None:
+      lxml.etree.SubElement(elt, "{%s}%s" % (self.xmlns, name), nsmap = self.nsmap).text = base64.b64encode(value)
+
+  def __str__(self):
+    """Convert a base_elt object to string format."""
+    lxml.etree.tostring(self.toXML(), pretty_print = True, encoding = "us-ascii")
+
+  @classmethod
+  def make_pdu(cls, **kargs):
+    """Generic PDU constructor."""
+    self = cls()
+    for k,v in kargs.items():
+      if isinstance(v, bool):
+        v = 1 if v else 0
+      setattr(self, k, v)
+    return self
+
+class data_elt(base_elt):
+  """Virtual base class for PDUs that map to SQL objects.  These
+  objects all implement the create/set/get/list/destroy action
+  attribute.
+  """
+
+  def make_reply(self, r_pdu = None):
+    """Construct a reply PDU."""
+    if r_pdu is None:
+      r_pdu = self.__class__()
+      self.make_reply_clone_hook(r_pdu)
+      setattr(r_pdu, self.sql_template.index, getattr(self, self.sql_template.index))
+    else:
+      for b in r_pdu.booleans:
+        setattr(r_pdu, b, False)
+    r_pdu.action = self.action
+    r_pdu.tag = self.tag
+    return r_pdu
+
+  def make_reply_clone_hook(self, r_pdu):
+    """Overridable hook."""
+    pass
+
+  def serve_pre_save_hook(self, q_pdu, r_pdu):
+    """Overridable hook."""
+    pass
+
+  def serve_post_save_hook(self, q_pdu, r_pdu):
+    """Overridable hook."""
+    pass
+
+  def serve_create(self, r_msg):
+    """Handle a create action."""
+    r_pdu = self.make_reply()
+    self.serve_pre_save_hook(self, r_pdu)
+    self.sql_store()
+    setattr(r_pdu, self.sql_template.index, getattr(self, self.sql_template.index))
+    self.serve_post_save_hook(self, r_pdu)
+    r_msg.append(r_pdu)
+
+  def serve_set(self, r_msg):
+    """Handle a set action."""
+    db_pdu = self.serve_fetch_one()
+    r_pdu = self.make_reply()
+    for a in db_pdu.sql_template.columns[1:]:
+      v = getattr(self, a)
+      if v is not None:
+        setattr(db_pdu, a, v)
+    db_pdu.sql_mark_dirty()
+    db_pdu.serve_pre_save_hook(self, r_pdu)
+    db_pdu.sql_store()
+    db_pdu.serve_post_save_hook(self, r_pdu)
+    r_msg.append(r_pdu)
+
+  def serve_get(self, r_msg):
+    """Handle a get action."""
+    r_pdu = self.serve_fetch_one()
+    self.make_reply(r_pdu)
+    r_msg.append(r_pdu)
+
+  def serve_list(self, r_msg):
+    """Handle a list action for non-self objects."""
+    for r_pdu in self.serve_fetch_all():
+      self.make_reply(r_pdu)
+      r_msg.append(r_pdu)
+
+  def serve_destroy(self, r_msg):
+    """Handle a destroy action."""
+    db_pdu = self.serve_fetch_one()
+    db_pdu.sql_delete()
+    r_msg.append(self.make_reply())
+
+  def serve_dispatch(self, r_msg):
+    """Action dispatch handler."""
+    dispatch = { "create"  : self.serve_create,
+                 "set"     : self.serve_set,
+                 "get"     : self.serve_get,
+                 "list"    : self.serve_list,
+                 "destroy" : self.serve_destroy }
+    if self.action not in dispatch:
+      raise rpki.exceptions.BadQuery, "Unexpected query: action %s" % self.action
+    dispatch[self.action](r_msg)
+  
+  def unimplemented_control(self, *controls):
+    """Uniform handling for unimplemented control operations."""
+    unimplemented = [x for x in controls if getattr(self, x, False)]
+    if unimplemented:
+      raise rpki.exceptions.NotImplementedYet, "Unimplemented control %s" % ", ".join(unimplemented)
+
+class msg(list):
+  """Generic top-level PDU."""
+
+  def startElement(self, stack, name, attrs):
+    """Handle top-level PDU."""
+    if name == "msg":
+      assert self.version == int(attrs["version"])
+      self.type = attrs["type"]
+    else:
+      elt = self.pdus[name]()
+      self.append(elt)
+      stack.append(elt)
+      elt.startElement(stack, name, attrs)
+
+  def endElement(self, stack, name, text):
+    """Handle top-level PDU."""
+    assert name == "msg", "Unexpected name %s, stack %s" % (name, stack)
+    assert len(stack) == 1
+    stack.pop()
+
+  def __str__(self):
+    """Convert msg object to string."""
+    lxml.etree.tostring(self.toXML(), pretty_print = True, encoding = "us-ascii")
+
+  def toXML(self):
+    """Generate top-level PDU."""
+    elt = lxml.etree.Element("{%s}msg" % (self.xmlns), nsmap = self.nsmap, version = str(self.version), type = self.type)
+    elt.extend([i.toXML() for i in self])
+    return elt