# $Id$

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

import base64, lxml.etree, time
import rpki.sax_utils, rpki.resource_set, rpki.x509, rpki.exceptions

xmlns="http://www.apnic.net/specs/rescerts/up-down/"

nsmap = { None : xmlns }

oid2name = {
  (1, 2, 840, 113549, 1, 1, 11) : "sha256WithRSAEncryption",
  (1, 2, 840, 113549, 1, 1, 12) : "sha384WithRSAEncryption",
  (1, 2, 840, 113549, 1, 1, 13) : "sha512WithRSAEncryption",
  (2, 5, 29, 19)                : "basicConstraints",
  (2, 5, 29, 15)                : "keyUsage",
  (1, 3, 6, 1, 5, 5, 7, 1, 11)  : "subjectInfoAccess",
  (1, 3, 6, 1, 5, 5, 7, 48, 2)  : "caIssuers",
  (1, 3, 6, 1, 5, 5, 7, 48, 5)  : "caRepository",
  (1, 3, 6, 1, 5, 5, 7, 48, 9)  : "signedObjectRepository",
  (1, 3, 6, 1, 5, 5, 7, 48, 10) : "rpkiManifest",
}

name2oid = dict((v,k) for k,v in oid2name.items())

class base_elt(object):
  """Generic PDU object.

  Virtual class, just provides some default methods.
  """

  def startElement(self, stack, name, attrs):
    """Ignore startElement() if there's no specific handler.

    Some elements have no attributes and we only care about their
    text content.
    """
    pass

  def endElement(self, stack, name, text):
    """Ignore endElement() if there's no specific handler.

    If we don't need to do anything else, just pop the stack.
    """
    stack.pop()

  def make_elt(self, name, *attrs):
    """Construct a element, copying over a set of attributes."""
    elt = lxml.etree.Element("{%s}%s" % (xmlns, name), nsmap=nsmap)
    for key in attrs:
      val = getattr(self, key, None)
      if val is not None:
        elt.set(key, str(val))
    return elt

  def make_b64elt(self, elt, name, value=None):
    """Construct a sub-element with Base64 text content."""
    if value is None:
      value = getattr(self, name, None)
    if value is not None:
      lxml.etree.SubElement(elt, "{%s}%s" % (xmlns, name), nsmap=nsmap).text = base64.b64encode(value)

  def serve_pdu(self, gctx, q_msg, r_msg, child):
    raise rpki.exceptions.BadQuery, "Unexpected query type %s" % q_msg.type

class multi_uri(list):
  """Container for a set of URIs."""

  def __init__(self, ini):
    """Initialize a set of URIs, which includes basic some syntax checking."""
    if isinstance(ini, (list, tuple)):
      self[:] = ini
    elif isinstance(ini, str):
      self[:] = ini.split(",")
      for s in self:
        if s.strip() != s or s.find("://") < 0:
          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

class certificate_elt(base_elt):
  """Up-Down protocol representation of an issued certificate."""

  def startElement(self, stack, name, attrs):
    """Handle attributes of <certificate/> element."""
    assert name == "certificate", "Unexpected name %s, stack %s" % (name, stack)
    self.cert_url = multi_uri(attrs["cert_url"])
    self.req_resource_set_as   = rpki.resource_set.resource_set_as(attrs.get("req_resource_set_as"))
    self.req_resource_set_ipv4 = rpki.resource_set.resource_set_ipv4(attrs.get("req_resource_set_ipv4"))
    self.req_resource_set_ipv6 = rpki.resource_set.resource_set_ipv6(attrs.get("req_resource_set_ipv6"))

  def endElement(self, stack, name, text):
    """Handle text content of a <certificate/> element."""
    assert name == "certificate", "Unexpected name %s, stack %s" % (name, stack)
    self.cert = rpki.x509.X509(Base64=text)
    stack.pop()

  def toXML(self):
    """Generate a <certificate/> element."""
    elt = self.make_elt("certificate", "cert_url", "req_resource_set_as", "req_resource_set_ipv4", "req_resource_set_ipv6")
    elt.text = self.cert.get_Base64()
    return elt

class class_elt(base_elt):
  """Up-Down protocol representation of a resource class."""

  def __init__(self):
    self.certs = []

  def startElement(self, stack, name, attrs):
    """Handle <class/> elements and their children."""
    if name == "certificate":
      cert = certificate_elt()
      self.certs.append(cert)
      stack.append(cert)
      cert.startElement(stack, name, attrs)
    elif name != "issuer":
      assert name == "class", "Unexpected name %s, stack %s" % (name, stack)
      self.class_name = attrs["class_name"]
      self.cert_url = multi_uri(attrs["cert_url"])
      self.suggested_sia_head = attrs.get("suggested_sia_head")
      self.resource_set_as   = rpki.resource_set.resource_set_as(attrs["resource_set_as"])
      self.resource_set_ipv4 = rpki.resource_set.resource_set_ipv4(attrs["resource_set_ipv4"])
      self.resource_set_ipv6 = rpki.resource_set.resource_set_ipv6(attrs["resource_set_ipv6"])

  def endElement(self, stack, name, text):
    """Handle <class/> elements and their children."""
    if name == "issuer":
      self.issuer = rpki.x509.X509(Base64=text)
    else:
      assert name == "class", "Unexpected name %s, stack %s" % (name, stack)
      stack.pop()

  def toXML(self):
    """Generate a <class/> element."""
    elt = self.make_elt("class", "class_name", "cert_url", "resource_set_as", "resource_set_ipv4", "resource_set_ipv6", "suggested_sia_head")
    elt.extend([i.toXML() for i in self.certs])
    self.make_b64elt(elt, "issuer", self.issuer.get_DER())
    return elt

class list_pdu(base_elt):
  """Up-Down protocol "list" PDU."""

  def toXML(self):
    """Generate (empty) payload of "list" PDU."""
    return []

  def serve_pdu(self, gctx, q_msg, r_msg, child):
    """Serve one "list" PDU."""
    r_msg.payload = list_response_pdu()
    irdb_as, irdb_v4, irdb_v6 = rpki.left_right.irdb_query(gctx, child.self_id, child.child_id)
    for ca_id in rpki.sql.fetch_column(gctx, "SELECT ca_id FROM ca WHERE ca.parent_id = parent.parent_id AND parent.self_id = %s" % child.self_id):
      ca_detail = rpki.sql.ca_detail_obj.sql_fetch_active(gctx, ca_id)
      if not ca_detail:
        continue
      rc_as, rc_v4, rc_v6 = ca_detail.latest_ca_cert.get_3779resources(irdb_as, irdb_v4, irdb_v6)
      if not rc_as and not rc_v4 and not rc_v6:
        continue
      rc = class_elt()
      rc.class_name = str(ca_id)
      rc.cert_url = multi_uri(ca_detail.ca_cert_uri)
      rc.resource_set_as, rc.resource_set_ipv4, rc.resource_set_ipv6 = rc_as, rc_v4, rc_v6
      for child_cert in rpki.sql.child_cert_obj.sql_fetch_where(gctx, "child_id = %s AND ca_detail_id = %s" % (child.child_id, ca_detail.ca_detail_id)):
        c = certificate_elt()
        c.cert_url = multi_uri(ca.sia_uri + child_cert.cert.gSKI() + ".cer")
        c.cert = child_cert.cert
        rc.certs.append(c)
      rc.issuer = ca_detail.latest_ca_cert
      r_msg.payload.classes.append(rc)

  @classmethod
  def query(cls, gctx, parent):
    """Send a "list" query to parent."""
    self = cls()
    return parent.query_up_down(gctx, self)

class class_response_syntax(base_elt):
  """Syntax for Up-Down protocol "list_response" and "issue_response" PDUs."""

  def __init__(self):
    self.classes = []

  def startElement(self, stack, name, attrs):
    """Handle "list_response" and "issue_response" PDUs."""
    assert name == "class", "Unexpected name %s, stack %s" % (name, stack)
    c = class_elt()
    self.classes.append(c)
    stack.append(c)
    c.startElement(stack, name, attrs)
      
  def toXML(self):
    """Generate payload of "list_response" and "issue_response" PDUs."""
    return [c.toXML() for c in self.classes]

class list_response_pdu(class_response_syntax):
    """Up-Down protocol "list_response" PDU."""

    pass

class issue_pdu(base_elt):
  """Up-Down protocol "issue" PDU."""

  def startElement(self, stack, name, attrs):
    """Handle "issue" PDU."""
    assert name == "request", "Unexpected name %s, stack %s" % (name, stack)
    self.class_name = attrs["class_name"]
    self.req_resource_set_as   = rpki.resource_set.resource_set_as(attrs.get("req_resource_set_as"))
    self.req_resource_set_ipv4 = rpki.resource_set.resource_set_ipv4(attrs.get("req_resource_set_ipv4"))
    self.req_resource_set_ipv6 = rpki.resource_set.resource_set_ipv6(attrs.get("req_resource_set_ipv6"))

  def endElement(self, stack, name, text):
    """Handle "issue" PDU."""
    assert name == "request", "Unexpected name %s, stack %s" % (name, stack)
    self.pkcs10 = rpki.x509.PKCS10(Base64=text)
    stack.pop()

  def toXML(self):
    """Generate payload of "issue" PDU."""
    elt = self.make_elt("request", "class_name", "req_resource_set_as", "req_resource_set_ipv4", "req_resource_set_ipv6")
    elt.text = self.pkcs10.get_Base64()
    return [elt]

  def serve_pdu(self, gctx, q_msg, r_msg, child):
    #
    # Step 1: Check the request
    if not self.class_name.isdigit():
      raise rpki.exceptions.BadClassNameSyntax, "Bad class name %s" % self.class_name
    ca_id = long(self.class_name)
    ca = rpki.sql.ca_obj.sql_fetch(gctx, ca_id)
    ca_detail = rpki.sql.ca_detail_obj.sql_fetch_active(gctx, ca_id)
    if ca is None or ca_detail is None:
      raise rpki.exceptions.NotInDatabase
    self.pkcs10.check_valid_rpki()
    #
    # Step 2: See whether we can just return the current child cert
    rc_as, rc_v4, rc_v6 = ca_detail.latest_ca_cert.get_3779resources(rpki.left_right.irdb_query(gctx, child.self_id, child.child_id))
    pubkey = self.pkcs10.getPublicKey()
    req_sia = self.pkcs10.get_SIA()
    #
    # This next search loop might be an argument for a child_cert.ski column
    for child_cert in rpki.sql.child_cert_obj.sql_fetch_where(gctx, "child_id = %s AND ca_detail_id = %s" % (child.child_id, ca_detail.ca_detail_id)):
      if child_cert.cert.getPublicKey() == pubkey:
        break
    else:
      child_cert = None
    if child_cert is not None and ((rc_as, rc_v4, rc_v6) != child_cert.cert.get_3779resources()):
      child_cert = None
    if child_cert is not None and child_cert.cert.get_SIA() != req_sia:
      child_cert = None
    # Do we need to check certificate expiration here too?  Maybe we
    # can just trust the cron job that handles renewals for that?
    #
    # Step 3: If we didn't find a reusable cert, generate a new one.
    if child_cert is None:
      # Some of this code probably should become a method of rpki.sql.ca_obj
      child_cert = rpki.sql.child_cert_obj()
      child_cert.child_id = child.child_id
      child_cert.ca_detail_id = ca_detail.ca_detail_id
      child_cert.cert = ca_detail.latest_ca_cert.issue(keypair = ca_detail.private_key_id,
                                                       subject_key = pubkey,
                                                       serial = ca.next_serial(),
                                                       aia = ca_detail.ca_cert_uri,
                                                       crldp = ca.sia_uri + ca_detail.latest_ca_cert.gSKI() + ".crl",
                                                       sia = req_sia,
                                                       as = rc_as,
                                                       v4 = rc_v4,
                                                       v6 = rc_v6)
      child_cert.sql_mark_dirty()

      raise NotImplementedError, "Should generate a new manifest, should publish newly-created certificate"

    # Save anything we modified and generate response
    rpki.sql.sql_sweep(gctx)
    assert child_cert and child_cert.sql_in_db
    c = certificate_elt()
    c.cert_url = multi_uri(ca.sia_uri + child_cert.cert.gSKI() + ".cer")
    c.cert = child_cert.cert
    rc = class_elt()
    rc.cert_url = multi_uri(ca_detail.ca_cert_uri)
    rc.resource_set_as, rc.resource_set_ipv4, rc.resource_set_ipv6 = rc_as, rc_v4, rc_v6
    rc.certs.append(c)
    rc.issuer = ca_detail.latest_ca_cert
    r_msg.payload = issue_response_pdu()
    r_msg.payload.classes.append(rc)

  @classmethod
  def query(cls, gctx, parent, ca, ca_detail):
    """Send an "issue" request to parent associated with ca."""
    assert ca_detail is not None and ca_detail.state != "deprecated"
    sia = (((1, 3, 6, 1, 5, 5, 7, 48, 5),  ("uri", ca.sia_uri)),
           ((1, 3, 6, 1, 5, 5, 7, 48, 10), ("uri", ca.sia_uri + ca_detail.public_key.gSKI() + ".mnf")))
    self = cls()
    self.class_name = ca.parent_resource_class
    self.pkcs10 = rpki.x509.PKCS10.create_ca(ca_detail.private_key_id, sia)
    return parent.query_up_down(gctx, self)

class issue_response_pdu(class_response_syntax):
  """Up-Down protocol "issue_response" PDU."""

  def check(self):
    """Check whether this looks like a reasonable issue_response PDU.
    XML schema should be tighter for this response.
    """
    if len(self.classes) != 1 or len(self.classes[0].certs) != 1:
      raise rpki.exceptions.BadIssueResponse

class revoke_syntax(base_elt):
  """Syntax for Up-Down protocol "revoke" and "revoke_response" PDUs."""

  def startElement(self, stack, name, attrs):
    """Handle "revoke" PDU."""
    self.class_name = attrs["class_name"]
    self.ski = attrs["ski"]

  def toXML(self):
    """Generate payload of "revoke" PDU."""
    return [self.make_elt("key", "class_name", "ski")]

class revoke_pdu(revoke_syntax):
  """Up-Down protocol "revoke" PDU."""

  def serve_pdu(self, gctx, q_msg, r_msg, child):
    if not self.class_name.isdigit():
      raise rpki.exceptions.BadClassNameSyntax, "Bad class name %s" % self.class_name
    ca_id = long(self.class_name)
    ca = rpki.sql.ca_obj.sql_fetch(gctx, ca_id)
    ca_detail = rpki.sql.ca_detail_obj.sql_fetch_active(gctx, ca_id)
    if ca is None or ca_detail is None:
      raise rpki.exceptions.NotInDatabase
    ski = base64.b64decode(self.ski.replace("_", "/").replace("-", "+"))
    # This next search loop might be an argument for a child_cert.ski column
    for c in rpki.sql.child_cert_obj.sql_fetch_where(gctx, "child_id = %s AND ca_detail_id = %s" % (child.child_id, ca_detail.ca_detail_id)):
      if c.cert.get_SKI() == ski:
        c.sql_delete()
    r_msg.payload = revoke_response_pdu()
    r_msg.payload.class_name = self.class_name
    r_msg.payload.ski = self.ski

  @classmethod
  def query(cls, gctx, ca_detail):
    """Send a "revoke" request to parent associated with ca_detail."""
    ca = rpki.sql.ca_obj.sql_fetch(gctx, ca_detail.ca_id)
    parent = rpki.left_right.parent_elt.sql_fetch(gctx, ca.parent_id)
    self = cls()
    self.class_name = ca.parent_resource_class
    self.ski = ca_detail.latest_ca_cert.gSKI()
    return parent.query_up_down(gctx, self)

class revoke_response_pdu(revoke_syntax):
  """Up-Down protocol "revoke_response" PDU."""

  pass

class error_response_pdu(base_elt):
  """Up-Down protocol "error_response" PDU."""

  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" }

  def endElement(self, stack, name, text):
    """Handle "error_response" PDU."""
    if name == "status":
      code = int(text)
      if code not in self.codes:
        raise rpki.exceptions.BadStatusCode, "%s is not a known status code"
      self.status = code
    elif name == "last_message_processed":
      self.last_message_processed = text
    elif name == "description":
      self.description = text
    else:
      assert name == "message", "Unexpected name %s, stack %s" % (name, stack)
      stack.pop()
      stack[-1].endElement(stack, name, text)

  def toXML(self):
    """Generate payload of "error_response" PDU."""
    assert self.status in self.codes
    elt = self.make_elt("status")
    elt.text = str(self.status)
    return [elt]

class message_pdu(base_elt):
  """Up-Down protocol message wrapper PDU."""

  version = 1

  name2type = {
    "list"            : list_pdu,
    "list_response"   : list_response_pdu,
    "issue"           : issue_pdu,
    "issue_response"  : issue_response_pdu,
    "revoke"          : revoke_pdu,
    "revoke_response" : revoke_response_pdu,
    "error_response"  : error_response_pdu }

  type2name = dict((v,k) for k,v in name2type.items())

  def toXML(self):
    """Generate payload of message PDU."""
    elt = self.make_elt("message", "version", "sender", "recipient", "type")
    elt.extend(self.payload.toXML())
    return elt

  def startElement(self, stack, name, attrs):
    """Handle message PDU.

    Payload of the <message/> element varies depending on the "type"
    attribute, so after some basic checks we have to instantiate the
    right class object to handle whatever kind of PDU this is.
    """
    assert name == "message", "Unexpected name %s, stack %s" % (name, stack)
    assert self.version == int(attrs["version"])
    self.sender = attrs["sender"]
    self.recipient = attrs["recipient"]
    self.type = attrs["type"]
    self.payload = self.name2type[attrs["type"]]()
    stack.append(self.payload)

  def __str__(self):
    lxml.etree.tostring(self.toXML(), pretty_print=True, encoding="UTF-8")

  def serve_top_level(self, gctx, child):
    r_msg = message_pdu()
    r_msg.sender = self.receiver
    r_msg.receiver = self.sender
    self.payload.serve_pdu(gctx, self, r_msg, child)
    return r_msg

  @classmethod
  def make_query(cls, payload, sender = "tweedledee", recipient = "tweedledum"):
    assert not self.type2name[type(payload)].endswith("_response")
    self = cls()
    self.sender = sender
    self.recipient = recipient
    self.payload = payload
    self.type = self.type2name[type(payload)]
    return self

class sax_handler(rpki.sax_utils.handler):
  """SAX handler for Up-Down protocol."""

  def create_top_level(self, name, attrs):
    """Top-level PDU for this protocol is <message/>."""
    return message_pdu()