/usr/lib/python2.7/dist-packages/kdcproxy/__init__.py is in python-kdcproxy 0.3.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# All rights reserved.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
import io
import logging
import select
import socket
import struct
import sys
import time
try: # Python 3.x
import http.client as httplib
import urllib.parse as urlparse
except ImportError: # Python 2.x
import httplib
import urlparse
import kdcproxy.codec as codec
from kdcproxy.config import MetaResolver
class HTTPException(Exception):
def __init__(self, code, msg, headers=[]):
headers = list(filter(lambda h: h[0] != 'Content-Length', headers))
if 'Content-Type' not in dict(headers):
headers.append(('Content-Type', 'text/plain; charset=utf-8'))
if sys.version_info.major == 3 and isinstance(msg, str):
msg = bytes(msg, "utf-8")
headers.append(('Content-Length', str(len(msg))))
super(HTTPException, self).__init__(code, msg, headers)
self.code = code
self.message = msg
self.headers = headers
def __str__(self):
return "%d %s" % (self.code, httplib.responses[self.code])
class Application:
MAX_LENGTH = 128 * 1024
SOCKTYPES = {
"tcp": socket.SOCK_STREAM,
"udp": socket.SOCK_DGRAM,
}
def __init__(self):
self.__resolver = MetaResolver()
def __await_reply(self, pr, rsocks, wsocks, timeout):
extra = 0
read_buffers = {}
while (timeout + extra) > time.time():
if not wsocks and not rsocks:
break
r, w, x = select.select(rsocks, wsocks, rsocks + wsocks,
(timeout + extra) - time.time())
for sock in x:
sock.close()
try:
rsocks.remove(sock)
except ValueError:
pass
try:
wsocks.remove(sock)
except ValueError:
pass
for sock in w:
try:
if self.sock_type(sock) == socket.SOCK_DGRAM:
# If we proxy over UDP, remove the 4-byte length
# prefix since it is TCP only.
sock.sendall(pr.request[4:])
else:
sock.sendall(pr.request)
extra = 10 # New connections get 10 extra seconds
except Exception:
logging.exception('Error in recv() of %s', sock)
continue
rsocks.append(sock)
wsocks.remove(sock)
for sock in r:
try:
reply = self.__handle_recv(sock, read_buffers)
except Exception:
logging.exception('Error in recv() of %s', sock)
if self.sock_type(sock) == socket.SOCK_STREAM:
# Remove broken TCP socket from readers
rsocks.remove(sock)
else:
if reply is not None:
return reply
return None
def __handle_recv(self, sock, read_buffers):
if self.sock_type(sock) == socket.SOCK_DGRAM:
# For UDP sockets, recv() returns an entire datagram
# package. KDC sends one datagram as reply.
reply = sock.recv(1048576)
# If we proxy over UDP, we will be missing the 4-byte
# length prefix. So add it.
reply = struct.pack("!I", len(reply)) + reply
return reply
else:
# TCP is a different story. The reply must be buffered
# until the full answer is accumulated.
buf = read_buffers.get(sock)
part = sock.recv(1048576)
if buf is None:
if len(part) > 4:
# got enough data in the initial package. Now check
# if we got the full package in the first run.
(length, ) = struct.unpack("!I", part[0:4])
if length + 4 == len(part):
return part
read_buffers[sock] = buf = io.BytesIO()
if part:
# data received, accumulate it in a buffer
buf.write(part)
return None
else:
# EOF received
read_buffers.pop(sock)
reply = buf.getvalue()
return reply
def __filter_addr(self, addr):
if addr[0] not in (socket.AF_INET, socket.AF_INET6):
return False
if addr[1] not in (socket.SOCK_STREAM, socket.SOCK_DGRAM):
return False
if addr[2] not in (socket.IPPROTO_TCP, socket.IPPROTO_UDP):
return False
return True
def sock_type(self, sock):
try:
return sock.type & ~socket.SOCK_NONBLOCK
except AttributeError:
return sock.type
def __call__(self, env, start_response):
try:
# Validate the method
method = env["REQUEST_METHOD"].upper()
if method != "POST":
raise HTTPException(405, "Method not allowed (%s)." % method)
# Parse the request
try:
length = int(env["CONTENT_LENGTH"])
except AttributeError:
raise HTTPException(411, "Length required.")
if length < 0:
raise HTTPException(411, "Length required.")
if length > self.MAX_LENGTH:
raise HTTPException(413, "Request entity too large.")
try:
pr = codec.decode(env["wsgi.input"].read(length))
except codec.ParsingError as e:
raise HTTPException(400, e.message)
# Find the remote proxy
servers = self.__resolver.lookup(
pr.realm,
kpasswd=isinstance(pr, codec.KPASSWDProxyRequest)
)
if not servers:
raise HTTPException(503, "Can't find remote (%s)." % pr)
# Contact the remote server
reply = None
wsocks = []
rsocks = []
for server in map(urlparse.urlparse, servers):
# Enforce valid, supported URIs
scheme = server.scheme.lower().split("+", 1)
if scheme[0] not in ("kerberos", "kpasswd"):
continue
if len(scheme) > 1 and scheme[1] not in ("tcp", "udp"):
continue
# Do the DNS lookup
try:
port = server.port
if port is None:
port = scheme[0]
addrs = socket.getaddrinfo(server.hostname, port)
except socket.gaierror:
continue
# Sort addresses so that we get TCP first.
#
# Stick a None address on the end so we can get one
# more attempt after all servers have been contacted.
addrs = tuple(sorted(filter(self.__filter_addr, addrs)))
for addr in addrs + (None,):
if addr is not None:
# Bypass unspecified socktypes
if (len(scheme) > 1
and addr[1] != self.SOCKTYPES[scheme[1]]):
continue
# Create the socket
sock = socket.socket(*addr[:3])
sock.setblocking(0)
# Connect
try:
# In Python 2.x, non-blocking connect() throws
# socket.error() with errno == EINPROGRESS. In
# Python 3.x, it throws io.BlockingIOError().
sock.connect(addr[4])
except socket.error as e:
if e.errno != 115: # errno != EINPROGRESS
sock.close()
continue
except io.BlockingIOError:
pass
wsocks.append(sock)
# Resend packets to UDP servers
for sock in tuple(rsocks):
if self.sock_type(sock) == socket.SOCK_DGRAM:
wsocks.append(sock)
rsocks.remove(sock)
# Call select()
timeout = time.time() + (15 if addr is None else 2)
reply = self.__await_reply(pr, rsocks, wsocks, timeout)
if reply is not None:
break
if reply is not None:
break
for sock in rsocks + wsocks:
sock.close()
if reply is None:
raise HTTPException(503, "Remote unavailable (%s)." % pr)
# Return the result to the client
raise HTTPException(200, codec.encode(reply),
[("Content-Type", "application/kerberos")])
except HTTPException as e:
start_response(str(e), e.headers)
return [e.message]
application = Application()
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