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import os
import subprocess as ssubprocess
from sshuttle.methods import BaseMethod
from sshuttle.helpers import log, debug1, debug2, debug3, \
Fatal, family_to_string, get_env, which
import socket
IP_BINDANY = 24
IP_RECVDSTADDR = 7
SOL_IPV6 = 41
IPV6_RECVDSTADDR = 74
def recv_udp(listener, bufsize):
debug3('Accept UDP python using recvmsg.')
data, ancdata, _, srcip = listener.recvmsg(4096,
socket.CMSG_SPACE(4))
dstip = None
for cmsg_level, cmsg_type, cmsg_data in ancdata:
if cmsg_level == socket.SOL_IP and cmsg_type == IP_RECVDSTADDR:
port = 53
ip = socket.inet_ntop(socket.AF_INET, cmsg_data[0:4])
dstip = (ip, port)
break
return (srcip, dstip, data)
def ipfw_rule_exists(n):
argv = ['ipfw', 'list', '%d' % n]
p = ssubprocess.Popen(argv, stdout=ssubprocess.PIPE, env=get_env())
found = False
for line in p.stdout:
if line.startswith(b'%05d ' % n):
if 'check-state :sshuttle' not in line:
log('non-sshuttle ipfw rule: %r' % line.strip())
raise Fatal('non-sshuttle ipfw rule #%d already exists!' % n)
found = True
break
rv = p.wait()
if rv:
raise Fatal('%r returned %d' % (argv, rv))
return found
_oldctls = {}
def _fill_oldctls(prefix):
argv = ['sysctl', prefix]
p = ssubprocess.Popen(argv, stdout=ssubprocess.PIPE, env=get_env())
for line in p.stdout:
line = line.decode()
assert line[-1] == '\n'
(k, v) = line[:-1].split(': ', 1)
_oldctls[k] = v.strip()
rv = p.wait()
if rv:
raise Fatal('%r returned %d' % (argv, rv))
if not line:
raise Fatal('%r returned no data' % (argv,))
def _sysctl_set(name, val):
argv = ['sysctl', '-w', '%s=%s' % (name, val)]
debug1('>> %s' % ' '.join(argv))
return ssubprocess.call(argv, stdout=open(os.devnull, 'w'), env=get_env())
# No env: No output. (Or error that won't be parsed.)
_changedctls = []
def sysctl_set(name, val, permanent=False):
PREFIX = 'net.inet.ip'
assert name.startswith(PREFIX + '.')
val = str(val)
if not _oldctls:
_fill_oldctls(PREFIX)
if not (name in _oldctls):
debug1('>> No such sysctl: %r' % name)
return False
oldval = _oldctls[name]
if val != oldval:
rv = _sysctl_set(name, val)
if rv == 0 and permanent:
debug1('>> ...saving permanently in /etc/sysctl.conf')
f = open('/etc/sysctl.conf', 'a')
f.write('\n'
'# Added by sshuttle\n'
'%s=%s\n' % (name, val))
f.close()
else:
_changedctls.append(name)
return True
def ipfw(*args):
argv = ['ipfw', '-q'] + list(args)
debug1('>> %s' % ' '.join(argv))
rv = ssubprocess.call(argv, env=get_env())
# No env: No output. (Or error that won't be parsed.)
if rv:
raise Fatal('%r returned %d' % (argv, rv))
def ipfw_noexit(*args):
argv = ['ipfw', '-q'] + list(args)
debug1('>> %s' % ' '.join(argv))
ssubprocess.call(argv, env=get_env())
# No env: No output. (Or error that won't be parsed.)
class Method(BaseMethod):
def get_supported_features(self):
result = super(Method, self).get_supported_features()
result.ipv6 = False
result.udp = False # NOTE: Almost there, kernel patch needed
result.dns = True
return result
def get_tcp_dstip(self, sock):
return sock.getsockname()
def recv_udp(self, udp_listener, bufsize):
srcip, dstip, data = recv_udp(udp_listener, bufsize)
if not dstip:
debug1(
"-- ignored UDP from %r: "
"couldn't determine destination IP address" % (srcip,))
return None
return srcip, dstip, data
def send_udp(self, sock, srcip, dstip, data):
if not srcip:
debug1(
"-- ignored UDP to %r: "
"couldn't determine source IP address" % (dstip,))
return
# debug3('Sending SRC: %r DST: %r' % (srcip, dstip))
sender = socket.socket(sock.family, socket.SOCK_DGRAM)
sender.setsockopt(socket.SOL_IP, IP_BINDANY, 1)
sender.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sender.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
sender.bind(srcip)
sender.sendto(data, dstip)
sender.close()
def setup_udp_listener(self, udp_listener):
if udp_listener.v4 is not None:
udp_listener.v4.setsockopt(socket.SOL_IP, IP_RECVDSTADDR, 1)
# if udp_listener.v6 is not None:
# udp_listener.v6.setsockopt(SOL_IPV6, IPV6_RECVDSTADDR, 1)
def setup_firewall(self, port, dnsport, nslist, family, subnets, udp,
user, tmark):
# IPv6 not supported
if family not in [socket.AF_INET]:
raise Exception(
'Address family "%s" unsupported by ipfw method_name'
% family_to_string(family))
# XXX: Any risk from this?
ipfw_noexit('delete', '1')
while _changedctls:
name = _changedctls.pop()
oldval = _oldctls[name]
_sysctl_set(name, oldval)
if subnets or dnsport:
sysctl_set('net.inet.ip.fw.enable', 1)
ipfw('add', '1', 'check-state', ':sshuttle')
ipfw('add', '1', 'skipto', '2',
'tcp',
'from', 'any', 'to', 'table(125)')
ipfw('add', '1', 'fwd', '127.0.0.1,%d' % port,
'tcp',
'from', 'any', 'to', 'table(126)',
'setup', 'keep-state', ':sshuttle')
ipfw_noexit('table', '124', 'flush')
dnscount = 0
for _, ip in [i for i in nslist if i[0] == family]:
ipfw('table', '124', 'add', '%s' % (ip))
dnscount += 1
if dnscount > 0:
ipfw('add', '1', 'fwd', '127.0.0.1,%d' % dnsport,
'udp',
'from', 'any', 'to', 'table(124)',
'keep-state', ':sshuttle')
ipfw('add', '1', 'allow',
'udp',
'from', 'any', 'to', 'any')
if subnets:
# create new subnet entries
for _, swidth, sexclude, snet, fport, lport \
in sorted(subnets, key=lambda s: s[1], reverse=True):
if sexclude:
ipfw('table', '125', 'add', '%s/%s' % (snet, swidth))
else:
ipfw('table', '126', 'add', '%s/%s' % (snet, swidth))
def restore_firewall(self, port, family, udp, user):
if family not in [socket.AF_INET]:
raise Exception(
'Address family "%s" unsupported by ipfw method'
% family_to_string(family))
ipfw_noexit('delete', '1')
ipfw_noexit('table', '124', 'flush')
ipfw_noexit('table', '125', 'flush')
ipfw_noexit('table', '126', 'flush')
def is_supported(self):
if which("ipfw"):
return True
debug2("ipfw method not supported because 'ipfw' command is "
"missing.")
return False
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