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import os
import subprocess as ssubprocess
from sshuttle.methods import BaseMethod
from sshuttle.helpers import log, debug1, debug3, \
Fatal, family_to_string
recvmsg = None
try:
# try getting recvmsg from python
import socket as pythonsocket
getattr(pythonsocket.socket, "recvmsg")
socket = pythonsocket
recvmsg = "python"
except AttributeError:
# try getting recvmsg from socket_ext library
try:
import socket_ext
getattr(socket_ext.socket, "recvmsg")
socket = socket_ext
recvmsg = "socket_ext"
except ImportError:
import socket
IP_BINDANY = 24
IP_RECVDSTADDR = 7
SOL_IPV6 = 41
IPV6_RECVDSTADDR = 74
if recvmsg == "python":
def recv_udp(listener, bufsize):
debug3('Accept UDP python using recvmsg.\n')
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)
elif recvmsg == "socket_ext":
def recv_udp(listener, bufsize):
debug3('Accept UDP using socket_ext recvmsg.\n')
srcip, data, adata, _ = \
listener.recvmsg((bufsize,), socket.CMSG_SPACE(4))
dstip = None
for a in adata:
if a.cmsg_level == socket.SOL_IP and a.cmsg_type == IP_RECVDSTADDR:
port = 53
ip = socket.inet_ntop(socket.AF_INET, a.cmsg_data[0:4])
dstip = (ip, port)
break
return (srcip, dstip, data[0])
else:
def recv_udp(listener, bufsize):
debug3('Accept UDP using recvfrom.\n')
data, srcip = listener.recvfrom(bufsize)
return (srcip, None, data)
def ipfw_rule_exists(n):
argv = ['ipfw', 'list']
env = {
'PATH': os.environ['PATH'],
'LC_ALL': "C",
}
p = ssubprocess.Popen(argv, stdout=ssubprocess.PIPE, env=env)
found = False
for line in p.stdout:
if line.startswith(b'%05d ' % n):
if not ('ipttl 42' in line or 'check-state' in line):
log('non-sshuttle ipfw rule: %r\n' % line.strip())
raise Fatal('non-sshuttle ipfw rule #%d already exists!' % n)
found = True
rv = p.wait()
if rv:
raise Fatal('%r returned %d' % (argv, rv))
return found
_oldctls = {}
def _fill_oldctls(prefix):
argv = ['sysctl', prefix]
env = {
'PATH': os.environ['PATH'],
'LC_ALL': "C",
}
p = ssubprocess.Popen(argv, stdout=ssubprocess.PIPE, env=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\n' % ' '.join(argv))
return ssubprocess.call(argv, stdout=open('/dev/null', 'w'))
_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\n' % 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\n')
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\n' % ' '.join(argv))
rv = ssubprocess.call(argv)
if rv:
raise Fatal('%r returned %d' % (argv, rv))
def ipfw_noexit(*args):
argv = ['ipfw', '-q'] + list(args)
debug1('>> %s\n' % ' '.join(argv))
ssubprocess.call(argv)
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\n" % (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\n" % (dstip,))
return
#debug3('Sending SRC: %r DST: %r\n' % (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.setsockopt(socket.SOL_IP, socket.IP_TTL, 42)
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):
# 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', 'ip',
'from', 'any', 'to', 'any')
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)',
'not', 'ipttl', '42', 'keep-state', 'setup')
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)',
'not', 'ipttl', '42')
ipfw('add', '1', 'allow',
'udp',
'from', 'any', 'to', 'any',
'ipttl', '42')
if subnets:
# create new subnet entries
for _, swidth, sexclude, snet \
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 tproxy method'
% family_to_string(family))
ipfw_noexit('delete', '1')
ipfw_noexit('table', '124', 'flush')
ipfw_noexit('table', '125', 'flush')
ipfw_noexit('table', '126', 'flush')
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