# $Id$
#
# Copyright (C) 2014  Dragon Research Labs ("DRL")
#
# 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 DRL DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS.  IN NO EVENT SHALL DRL 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.

"""
HTTP using Python standard libraries, for RPKI programs that don't
need the full-blown rpki.http asynchronous code.
"""

import logging
import httplib
import urlparse
import BaseHTTPServer

logger = logging.getLogger(__name__)


default_content_type = "application/x-rpki"


class HTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
  """
  HTTP request handler simple RPKI servers.
  """

  def do_POST(self):
    try:
      content_type   = self.headers.get("Content-Type")
      content_length = self.headers.get("Content-Length")
      for h in self.rpki_handlers:
        if self.path.startswith(h[0]):
          break
      else:
        self.send_error(404, "No handler for path %s" % self.path)
      if content_type not in (h[2] if len(h) > 2 else (default_content_type,)):
        self.send_error(415, "No handler for Content-Type %s" % content_type)
      h[1](self, (self.rfile.read()
                  if content_length is None else
                  self.rfile.read(int(content_length))))
    except Exception, e:
      logger.exception("Unhandled exception")
      self.send_error(501, "Unhandled exception")

  def send_cms_response(self, der):
    self.send_response(200)
    self.send_header("Content-Type", default_content_type)
    self.send_header("Content-Length", str(len(der)))
    self.end_headers()
    self.wfile.write(der)

  def log_message(self, *args):
    logger.info(*args, extra = dict(context = "%s:%s" % self.client_address))

  def send_error(self, code, message = None):
    # BaseHTTPRequestHandler.send_error() generates HTML error messages,
    # which we don't want, so we override the method to suppress this.
    self.send_response(code, message)
    self.send_header("Content-Type", default_content_type)
    self.send_header("Connection", "close")
    self.end_headers()


def server(handlers, port, host = ""):
  """
  Run an HTTP server and wait (forever) for connections.
  """

  if not isinstance(handlers, (tuple, list)):
    handlers = (("/", handlers),)

  class RequestHandler(HTTPRequestHandler):
    rpki_handlers = handlers

  BaseHTTPServer.HTTPServer((host, port), RequestHandler).serve_forever()


class BadURL(Exception):
  "Bad contact URL"

class RequestFailed(Exception):
  "HTTP returned failure"

class BadContentType(Exception):
  "Wrong HTTP Content-Type"


def client(proto_cms_msg, client_key, client_cert, server_ta, server_cert, url, q_msg,
           debug = False, replay_track = None, client_crl = None, content_type = default_content_type):
  """
  Issue single a query and return the response, handling all the CMS and XML goo.
  """

  u = urlparse.urlparse(url)

  if u.scheme not in ("", "http") or u.username or u.password or u.params or u.query or u.fragment:
    raise BadURL("Unusable URL %s", url)

  q_cms = proto_cms_msg()
  q_der = q_cms.wrap(q_msg, client_key, client_cert, client_crl)

  if debug:
    debug.write("<!-- Query -->\n" + q_cms.pretty_print_content() + "\n")

  http = httplib.HTTPConnection(u.hostname, u.port or httplib.HTTP_PORT)
  http.request("POST", u.path, q_der, {"Content-Type" : content_type})
  r = http.getresponse()

  if r.status != 200:
    raise RequestFailed("HTTP request failed with status %r reason %r" % (r.status, r.reason))

  if r.getheader("Content-Type") != content_type:
    raise BadContentType("HTTP Content-Type %r, expected %r" % (r.getheader("Content-Type"), content_type))

  r_der = r.read()
  r_cms = proto_cms_msg(DER = r_der)
  r_msg = r_cms.unwrap((server_ta, server_cert))

  if replay_track is not None:
    replay_track.cms_timestamp = r_cms.check_replay(replay_track.cms_timestamp, url)

  if debug:
    debug.write("<!-- Reply -->\n" + r_cms.pretty_print_content() + "\n")

  return r_msg