File: fp-reg-decryptd

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flashproxy 1.7-4
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#!/usr/bin/env python
"""
Accepts encrypted client registrations and forwards them to the facilitator.
"""

import SocketServer
import getopt
import os
import socket
import sys
import threading
import time

from flashproxy import fac
from flashproxy import proc
from flashproxy.util import format_addr

from M2Crypto import RSA

# Generating an RSA keypair for use by this program:
# openssl genrsa -out /etc/flashproxy/reg-daemon.key 2048
# chmod 600 /etc/flashproxy/reg-daemon.key

LISTEN_ADDRESS = "127.0.0.1"
DEFAULT_LISTEN_PORT = 9003
FACILITATOR_ADDR = ("127.0.0.1", 9002)
DEFAULT_LOG_FILENAME = "fp-reg-decryptd.log"

# Don't indulge clients for more than this many seconds.
CLIENT_TIMEOUT = 1.0
# Buffer no more than this many bytes per connection.
MAX_LENGTH = 40 * 1024

LOG_DATE_FORMAT = "%Y-%m-%d %H:%M:%S"

class options(object):
    key_filename = None
    listen_port = DEFAULT_LISTEN_PORT
    log_filename = DEFAULT_LOG_FILENAME
    log_file = sys.stdout
    daemonize = True
    pid_filename = None
    privdrop_username = None
    safe_logging = True

def usage(f = sys.stdout):
    print >> f, """\
Usage: %(progname)s --key=KEYFILE
Facilitator-side daemon that reads base64-encoded encrypted client
registrations and registers them with a local facilitator. This program
exists on its own in order to isolate the reading of key material in a
single process.

  -d, --debug               don't daemonize, log to stdout.
  -h, --help                show this help.
  -k, --key=KEYFILE         read the private key from KEYFILE (required).
  -l, --log FILENAME        write log to FILENAME (default \"%(log)s\").
  -p, --port PORT           listen on PORT (default %(port)d).
      --pidfile FILENAME    write PID to FILENAME after daemonizing.
      --privdrop-user USER  switch UID and GID to those of USER.
      --unsafe-logging      don't scrub IP addresses from logs.\
""" % {
    "progname": sys.argv[0],
    "log": DEFAULT_LOG_FILENAME,
    "port": DEFAULT_LISTEN_PORT,
}

def safe_str(s):
    """Return "[scrubbed]" if options.safe_logging is true, and s otherwise."""
    if options.safe_logging:
        return "[scrubbed]"
    else:
        return s

log_lock = threading.Lock()
def log(msg):
    log_lock.acquire()
    try:
        print >> options.log_file, (u"%s %s" % (time.strftime(LOG_DATE_FORMAT), msg)).encode("UTF-8")
        options.log_file.flush()
    finally:
        log_lock.release()

class Handler(SocketServer.StreamRequestHandler):
    def __init__(self, *args, **kwargs):
        self.deadline = time.time() + CLIENT_TIMEOUT
        self.buffer = ""
        SocketServer.StreamRequestHandler.__init__(self, *args, **kwargs)

    def recv(self):
        timeout = self.deadline - time.time()
        self.connection.settimeout(timeout)
        return self.connection.recv(1024)

    def read_input(self):
        while True:
            data = self.recv()
            if not data:
                break
            self.buffer += data
            buflen = len(self.buffer)
            if buflen > MAX_LENGTH:
                raise socket.error("refusing to buffer %d bytes (last read was %d bytes)" % (buflen, len(data)))
        return self.buffer

    @proc.catch_epipe
    def handle(self):
        try:
            b64_ciphertext = self.read_input()
        except socket.error, e:
            log("socket error reading input: %s" % str(e))
            return
        try:
            ciphertext = b64_ciphertext.decode("base64")
            plaintext = rsa.private_decrypt(ciphertext, RSA.pkcs1_oaep_padding)
            for client_reg in fac.read_client_registrations(plaintext):
                log(u"registering %s" % safe_str(format_addr(client_reg.addr)))
                if not fac.put_reg(FACILITATOR_ADDR, client_reg.addr, client_reg.transport):
                    print >> self.wfile, "FAIL"
                    break
            else:
                print >> self.wfile, "OK"
        except Exception, e:
            log("error registering: %s" % str(e))
            print >> self.wfile, "FAIL"
            raise

    finish = proc.catch_epipe(SocketServer.StreamRequestHandler.finish)

class Server(SocketServer.ThreadingMixIn, SocketServer.TCPServer):
    allow_reuse_address = True

def main():
    global rsa

    opts, args = getopt.gnu_getopt(sys.argv[1:], "dhk:l:p:",
        ["debug", "help", "key=", "log=", "port=", "pidfile=", "privdrop-user=", "unsafe-logging"])
    for o, a in opts:
        if o == "-d" or o == "--debug":
            options.daemonize = False
            options.log_filename = None
        elif o == "-h" or o == "--help":
            usage()
            sys.exit()
        elif o == "-k" or o == "--key":
            options.key_filename = a
        elif o == "-l" or o == "--log":
            options.log_filename = a
        elif o == "-p" or o == "--pass":
            options.listen_port = int(a)
        elif o == "--pidfile":
            options.pid_filename = a
        elif o == "--privdrop-user":
            options.privdrop_username = a
        elif o == "--unsafe-logging":
            options.safe_logging = False

    if len(args) != 0:
        usage(sys.stderr)
        sys.exit(1)

    # Load the private key.
    if options.key_filename is None:
        print >> sys.stderr, "The --key option is required."
        sys.exit(1)
    try:
        key_file = open(options.key_filename)
    except Exception, e:
        print >> sys.stderr, "Failed to open private key file \"%s\": %s." % (options.key_filename, str(e))
        sys.exit(1)
    try:
        if not proc.check_perms(key_file.fileno()):
            print >> sys.stderr, "Refusing to run with group- or world-readable private key file. Try"
            print >> sys.stderr, "\tchmod 600 %s" % options.key_filename
            sys.exit(1)
        rsa = RSA.load_key_string(key_file.read())
    finally:
        key_file.close()

    if options.log_filename:
        options.log_file = open(options.log_filename, "a")
        # Send error tracebacks to the log.
        sys.stderr = options.log_file
    else:
        options.log_file = sys.stdout

    addrinfo = socket.getaddrinfo(LISTEN_ADDRESS, options.listen_port, 0, socket.SOCK_STREAM, socket.IPPROTO_TCP)[0]

    server = Server(addrinfo[4], Handler)

    log(u"start on %s" % format_addr(addrinfo[4]))

    if options.daemonize:
        log(u"daemonizing")
        pid = os.fork()
        if pid != 0:
            if options.pid_filename:
                f = open(options.pid_filename, "w")
                print >> f, pid
                f.close()
            sys.exit(0)

    if options.privdrop_username is not None:
        log(u"dropping privileges to those of user %s" % options.privdrop_username)
        try:
            proc.drop_privs(options.privdrop_username)
        except BaseException, e:
            print >> sys.stderr, "Can't drop privileges:", str(e)
            sys.exit(1)

    try:
        server.serve_forever()
    except KeyboardInterrupt:
        sys.exit(0)

if __name__ == "__main__":
    main()