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#!/usr/bin/python
# Notes
# -----
#
# 1. execute in a chroot jail
# 2. enforce resource limits
# 3. allow multiple connections
# 4. enforce some kind of auth.
#
# Another thing is to examine the commonality and difference between
# the console app and the python evaluator in the tutorial system.
import socket
import cStringIO
import codeop
import sys
import cjson
import signal
def recv_lines(sok):
buf = ''
s = sok.recv(4096)
while len(s) > 0:
buf = buf + s
i = buf.find('\r\n')
while i != -1:
l = buf[0:i]
yield l
buf = buf[i+2:]
i = buf.find('\r\n')
s = sok.recv(4096)
def auth_lines(lines, magic):
for line in lines:
digest = line[0:32]
txt = line[32:]
sum = md5.new(txt + magic).digest().encode('hex')
if sum != digest:
raise Exception, "digest failed!"
yeild txt
shutup_shop_on_timeout = False
keep_going = True
def timeout(signum, frame):
if shutup_shop_on_timeout:
keep_going = False
return
raise Exception, 'Timeout!'
# signal.signal(signal.SIGALRM, timeout)
#
# sok = socket.socket(socket.AF_INET)
# sok.bind(('localhost',9998))
# sok.listen(1)
# (new_sok,addr) = sok.accept()
#
# c = codeop.CommandCompiler()
#
# globs = {}
# locos = {}
# globs['__builtins__'] = globals()['__builtins__']
#
# out = cStringIO.StringIO()
# sys.stdout = out
# first = True
# for line in req_lines(new_sok):
# if first:
# src = line
# first = False
# else:
# src = src + '\n' + line
# cmd = c(src)
# if cmd is not None:
# signal.alarm(5)
# res = eval(cmd, globs, locos)
# signal.alarm(0)
# new_sok.send(cjson.encode((out.getvalue(),res)) + '\n')
# out = cStringIO.StringIO()
# sys.stdout = out
# first = True
#
# sok.shutdown(socket.SHUT_RDWR)
if __name__ == "__main__":
try:
uid = int(sys.argv[1])
except ValueError, v:
print >> sys.stderr, "uid must be an integer."
sys.exit(1)
jail = sys.argv[2]
cwd = sys.argv[3]
try:
port = int(sys.argv[4])
except ValueError, v:
print >> sys.stderr, "port must be an integer."
sys.exit(1)
magic = sys.argv[5]
# magic = raw_input()
try:
pid = os.fork()
if pid > 0:
sys.exit(0)
except OSError, e:
print >> sys.stderr, "fork #1 failed: %d (%s)" % (e.errno, e.strerror)
sys.exit(1)
# Okay, now decouple from the parent environment
os.chdir('/')
os.setsid()
os.umask(0)
# do second fork
try:
pid = os.fork()
if pid > 0:
sys.exit(0)
except OSError, e:
print >> sys.stderr, "fork #2 failed: %d (%s)" % (e.errno, e.strerror)
sys.exit(1)
# establish the chrooted environment
jail.setup(uid, jail, cwd)
signal.signal(signal.SIGALRM, timeout)
main_sok = socket.socket(socket.AF_INET)
main_sok.bind(('localhost',port))
main_sok.listen(1)
comp = codeop.CommandCompiler()
globs = {}
locos = {}
globs['__builtins__'] = globals()['__builtins__']
global keep_going
keep_going = True
while keep_going:
global shutup_shop_on_timeout
shutup_shop_on_timeout = True
signal.alarm(30 * 60) # timeout after 30 minutes
(sok,addr) = main_sok.accept()
signal.alarm(0)
shutup_shop_on_timeout = False
# FIXME do checks on addr
try:
first = True
# for line in auth_lines(req_lines(new_sok), magic):
for line in req_lines(new_sok):
if first:
src = line
first = False
else:
src = src + '\n' + line
try:
cmd = comp(src)
if cmd is not None:
signal.alarm(5)
res = eval(cmd, globs, locos)
signal.alarm(0)
rval = (out.getvalue(), res, None)
sok.send(cjson.encode(rval) + '\n')
out = cStringIO.StringIO()
sys.stdout = out
first = True
else:
sok.send(cjson.encode(None) + '\n')
except Exception, e:
rval = (None, None, str(e))
sok.send(cjson.encode(rval) + '\n')
out = cStringIO.StringIO()
sys.stdout = out
first = True
finally:
sok.close()
main_sok.shutdown(socket.SHUT_RDWR)
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