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import re, struct, socket, select, traceback, time
if not globals().get('skip_imports'):
import ssnet, helpers, hostwatch
import compat.ssubprocess as ssubprocess
from ssnet import SockWrapper, Handler, Proxy, Mux, MuxWrapper
from helpers import *
def _ipmatch(ipstr):
if ipstr == 'default':
ipstr = '0.0.0.0/0'
m = re.match(r'^(\d+(\.\d+(\.\d+(\.\d+)?)?)?)(?:/(\d+))?$', ipstr)
if m:
g = m.groups()
ips = g[0]
width = int(g[4] or 32)
if g[1] == None:
ips += '.0.0.0'
width = min(width, 8)
elif g[2] == None:
ips += '.0.0'
width = min(width, 16)
elif g[3] == None:
ips += '.0'
width = min(width, 24)
return (struct.unpack('!I', socket.inet_aton(ips))[0], width)
def _ipstr(ip, width):
if width >= 32:
return ip
else:
return "%s/%d" % (ip, width)
def _maskbits(netmask):
if not netmask:
return 32
for i in range(32):
if netmask[0] & _shl(1, i):
return 32-i
return 0
def _shl(n, bits):
return n * int(2**bits)
def _list_routes():
argv = ['netstat', '-rn']
p = ssubprocess.Popen(argv, stdout=ssubprocess.PIPE)
routes = []
for line in p.stdout:
cols = re.split(r'\s+', line)
ipw = _ipmatch(cols[0])
if not ipw:
continue # some lines won't be parseable; never mind
maskw = _ipmatch(cols[2]) # linux only
mask = _maskbits(maskw) # returns 32 if maskw is null
width = min(ipw[1], mask)
ip = ipw[0] & _shl(_shl(1, width) - 1, 32-width)
routes.append((socket.inet_ntoa(struct.pack('!I', ip)), width))
rv = p.wait()
if rv != 0:
log('WARNING: %r returned %d\n' % (argv, rv))
log('WARNING: That prevents --auto-nets from working.\n')
return routes
def list_routes():
for (ip,width) in _list_routes():
if not ip.startswith('0.') and not ip.startswith('127.'):
yield (ip,width)
def _exc_dump():
exc_info = sys.exc_info()
return ''.join(traceback.format_exception(*exc_info))
def start_hostwatch(seed_hosts):
s1,s2 = socket.socketpair()
pid = os.fork()
if not pid:
# child
rv = 99
try:
try:
s2.close()
os.dup2(s1.fileno(), 1)
os.dup2(s1.fileno(), 0)
s1.close()
rv = hostwatch.hw_main(seed_hosts) or 0
except Exception, e:
log('%s\n' % _exc_dump())
rv = 98
finally:
os._exit(rv)
s1.close()
return pid,s2
class Hostwatch:
def __init__(self):
self.pid = 0
self.sock = None
class DnsProxy(Handler):
def __init__(self, mux, chan, request):
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
Handler.__init__(self, [sock])
self.timeout = time.time()+30
self.mux = mux
self.chan = chan
self.tries = 0
self.peer = None
self.request = request
self.sock = sock
self.sock.setsockopt(socket.SOL_IP, socket.IP_TTL, 42)
self.try_send()
def try_send(self):
if self.tries >= 3:
return
self.tries += 1
self.peer = resolvconf_random_nameserver()
self.sock.connect((self.peer, 53))
debug2('DNS: sending to %r\n' % self.peer)
try:
self.sock.send(self.request)
except socket.error, e:
if e.args[0] in ssnet.NET_ERRS:
# might have been spurious; try again.
# Note: these errors sometimes are reported by recv(),
# and sometimes by send(). We have to catch both.
debug2('DNS send to %r: %s\n' % (self.peer, e))
self.try_send()
return
else:
log('DNS send to %r: %s\n' % (self.peer, e))
return
def callback(self):
try:
data = self.sock.recv(4096)
except socket.error, e:
if e.args[0] in ssnet.NET_ERRS:
# might have been spurious; try again.
# Note: these errors sometimes are reported by recv(),
# and sometimes by send(). We have to catch both.
debug2('DNS recv from %r: %s\n' % (self.peer, e))
self.try_send()
return
else:
log('DNS recv from %r: %s\n' % (self.peer, e))
return
debug2('DNS response: %d bytes\n' % len(data))
self.mux.send(self.chan, ssnet.CMD_DNS_RESPONSE, data)
self.ok = False
def main():
if helpers.verbose >= 1:
helpers.logprefix = ' s: '
else:
helpers.logprefix = 'server: '
debug1('latency control setting = %r\n' % latency_control)
routes = list(list_routes())
debug1('available routes:\n')
for r in routes:
debug1(' %s/%d\n' % r)
# synchronization header
sys.stdout.write('\0\0SSHUTTLE0001')
sys.stdout.flush()
handlers = []
mux = Mux(socket.fromfd(sys.stdin.fileno(),
socket.AF_INET, socket.SOCK_STREAM),
socket.fromfd(sys.stdout.fileno(),
socket.AF_INET, socket.SOCK_STREAM))
handlers.append(mux)
routepkt = ''
for r in routes:
routepkt += '%s,%d\n' % r
mux.send(0, ssnet.CMD_ROUTES, routepkt)
hw = Hostwatch()
hw.leftover = ''
def hostwatch_ready():
assert(hw.pid)
content = hw.sock.recv(4096)
if content:
lines = (hw.leftover + content).split('\n')
if lines[-1]:
# no terminating newline: entry isn't complete yet!
hw.leftover = lines.pop()
lines.append('')
else:
hw.leftover = ''
mux.send(0, ssnet.CMD_HOST_LIST, '\n'.join(lines))
else:
raise Fatal('hostwatch process died')
def got_host_req(data):
if not hw.pid:
(hw.pid,hw.sock) = start_hostwatch(data.strip().split())
handlers.append(Handler(socks = [hw.sock],
callback = hostwatch_ready))
mux.got_host_req = got_host_req
def new_channel(channel, data):
(dstip,dstport) = data.split(',', 1)
dstport = int(dstport)
outwrap = ssnet.connect_dst(dstip,dstport)
handlers.append(Proxy(MuxWrapper(mux, channel), outwrap))
mux.new_channel = new_channel
dnshandlers = {}
def dns_req(channel, data):
debug2('Incoming DNS request.\n')
h = DnsProxy(mux, channel, data)
handlers.append(h)
dnshandlers[channel] = h
mux.got_dns_req = dns_req
while mux.ok:
if hw.pid:
assert(hw.pid > 0)
(rpid, rv) = os.waitpid(hw.pid, os.WNOHANG)
if rpid:
raise Fatal('hostwatch exited unexpectedly: code 0x%04x\n' % rv)
ssnet.runonce(handlers, mux)
if latency_control:
mux.check_fullness()
mux.callback()
if dnshandlers:
now = time.time()
for channel,h in dnshandlers.items():
if h.timeout < now or not h.ok:
del dnshandlers[channel]
h.ok = False
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