# $Id$
#
# Copyright (C) 2013--2014  Dragon Research Labs ("DRL")
# Portions copyright (C) 2009--2012  Internet Systems Consortium ("ISC")
# Portions 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 notices and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND DRL, ISC, AND ARIN DISCLAIM ALL
# WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL DRL,
# ISC, OR 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.

"""
RPKI "up-down" protocol.
"""

import base64
import logging
import lxml.etree
import rpki.resource_set
import rpki.x509
import rpki.exceptions
import rpki.log
import rpki.xml_utils
import rpki.relaxng

from lxml.etree import Element, SubElement, tostring as ElementToString

logger = logging.getLogger(__name__)


xmlns   = rpki.relaxng.up_down.xmlns
nsmap   = rpki.relaxng.up_down.nsmap
version = "1"

tag_certificate = xmlns + "certificate"
tag_class       = xmlns + "class"
tag_description = xmlns + "description"
tag_issuer      = xmlns + "issuer"
tag_message     = xmlns + "message"
tag_request     = xmlns + "request"
tag_status      = xmlns + "status"


class multi_uri(list):
  """
  Container for a set of URIs.  This probably could be simplified.
  """

  def __init__(self, ini):
    list.__init__(self)
    if isinstance(ini, (list, tuple)):
      self[:] = ini
    elif isinstance(ini, str):
      self[:] = ini.split(",")
      for s in self:
        if s.strip() != s or "://" not in s:
          raise rpki.exceptions.BadURISyntax("Bad URI \"%s\"" % s)
    else:
      raise TypeError

  def __str__(self):
    return ",".join(self)

  def rsync(self):
    """
    Find first rsync://... URI in self.
    """

    for s in self:
      if s.startswith("rsync://"):
        return s
    return None


error_response_codes = {
  1101 : "Already processing request",
  1102 : "Version number error",
  1103 : "Unrecognised request type",
  1201 : "Request - no such resource class",
  1202 : "Request - no resources allocated in resource class",
  1203 : "Request - badly formed certificate request",
  1301 : "Revoke - no such resource class",
  1302 : "Revoke - no such key",
  2001 : "Internal Server Error - Request not performed" }


exception_map = {
  rpki.exceptions.NoActiveCA                    : 1202,
  (rpki.exceptions.ClassNameUnknown, "revoke")  : 1301,
  rpki.exceptions.ClassNameUnknown              : 1201,
  (rpki.exceptions.NotInDatabase,    "revoke")  : 1302 }


def check_response(r_msg, q_type):
  """
  Additional checks beyond the XML schema for whether this looks like
  a reasonable up-down response message.
  """

  r_type = r_msg.get("type")

  if r_type == "error_response":
    raise rpki.exceptions.UpstreamError(error_response_codes[int(r_msg.findtext(tag_status))])

  if r_type != q_type + "_response":
    raise UnexpectedUpDownResponse

  if r_type == "issue_response" and (len(r_msg) != 1 or len(r_msg[0]) != 2):
    logger.debug("Weird issue_response %r: len(r_msg) %s len(r_msg[0]) %s",
                 r_msg, len(r_msg), len(r_msg[0]) if len(r_msg) else None)
    logger.debug("Offending message\n%s", ElementToString(r_msg))
    raise rpki.exceptions.BadIssueResponse


def generate_error_response(r_msg, status = 2001, description = None):
  """
  Generate an error response.  If status is given, it specifies the
  numeric code to use, otherwise we default to "internal error".
  If description is specified, we use it as the description, otherwise
  we just use the default string associated with status.
  """

  assert status in error_response_codes
  del r_msg[:]
  r_msg.set("type", "error_response")
  SubElement(r_msg, tag_status).text = str(status)
  se = SubElement(r_msg, tag_description)
  se.set("{http://www.w3.org/XML/1998/namespace}lang", "en-US")
  se.text = str(description or error_response_codes[status])


def generate_error_response_from_exception(r_msg, e, q_type):
  """
  Construct an error response from an exception.  q_type
  specifies the kind of query to which this is a response, since the
  same exception can generate different codes in response to different
  queries.
  """

  t = type(e)
  code = (exception_map.get((t, q_type)) or exception_map.get(t) or 2001)
  generate_error_response(r_msg, code, e)


class cms_msg_no_sax(rpki.x509.XML_CMS_object):
  """
  Class to hold a CMS-signed up-down PDU.

  Name is a transition kludge: once we ditch SAX, this will become cms_msg.
  """

  encoding = "UTF-8"
  schema = rpki.relaxng.up_down
  allow_extra_certs = True
  allow_extra_crls = True