mirror of
https://github.com/sshuttle/sshuttle.git
synced 2024-11-25 01:13:37 +01:00
Improve hostwatch robustness and documentation.
If an exception occurs in hostwatch, sshuttle exits. Problems read/writing the ~/.sshuttle.hosts cache file on the remote machine would therefore cause sshuttle to exit. With this patch, we simply continue running without writing/reading the cache file in the remote home directory. This serves as an alternate fix for pull request #322 which proposed storing the cache file elsewhere. A list of included changes: - If we can't read or write the host cache file on the server, continue running. Hosts can be collected through the netstat, /etc/hosts, etc and the information can be reconstructed each run if a cache file isn't available to read. We write a log() message when this occurs. - Add additional types of exceptions to handle. - Continue even if we cannot read /etc/hosts on the server. - Update man page to mention the cache file on the remote host. - Indicate that messages are related to remote host instead of local host. - Add comments and descriptions to the code.
This commit is contained in:
Scott Kuhl
parent
a3cbf0885f
commit
560c6b4ce8
@ -89,6 +89,13 @@ Options
|
||||
few subnets over the VPN, you probably would prefer to
|
||||
keep using your local DNS server for everything else.
|
||||
|
||||
:program:`sshuttle` tries to store a cache of the hostnames in
|
||||
~/.sshuttle.hosts on the remote host. Similarly, it tries to read
|
||||
the file when you later reconnect to the host with --auto-hosts
|
||||
enabled to quickly populate the host list. When troubleshooting
|
||||
this feature, try removing this file on the remote host when
|
||||
sshuttle is not running.
|
||||
|
||||
.. option:: -N, --auto-nets
|
||||
|
||||
In addition to the subnets provided on the command
|
||||
@ -178,7 +185,7 @@ Options
|
||||
|
||||
A comma-separated list of hostnames to use to
|
||||
initialize the :option:`--auto-hosts` scan algorithm.
|
||||
:option:`--auto-hosts` does things like poll local SMB servers
|
||||
:option:`--auto-hosts` does things like poll netstat output
|
||||
for lists of local hostnames, but can speed things up
|
||||
if you use this option to give it a few names to start
|
||||
from.
|
||||
|
||||
@ -29,9 +29,12 @@ except IOError:
|
||||
def _is_ip(s):
|
||||
return re.match(r'\d+\.\d+\.\d+\.\d+$', s)
|
||||
|
||||
|
||||
CACHE_WRITE_FAILED = False
|
||||
def write_host_cache():
|
||||
"""If possible, write our hosts file to disk so future connections
|
||||
can reuse the hosts that we already found."""
|
||||
tmpname = '%s.%d.tmp' % (CACHEFILE, os.getpid())
|
||||
global CACHE_WRITE_FAILED
|
||||
try:
|
||||
f = open(tmpname, 'wb')
|
||||
for name, ip in sorted(hostnames.items()):
|
||||
@ -39,7 +42,15 @@ def write_host_cache():
|
||||
f.close()
|
||||
os.chmod(tmpname, 384) # 600 in octal, 'rw-------'
|
||||
os.rename(tmpname, CACHEFILE)
|
||||
finally:
|
||||
CACHE_WRITE_FAILED = False
|
||||
except (OSError, IOError):
|
||||
# Write message if we haven't yet or if we get a failure after
|
||||
# a previous success.
|
||||
if not CACHE_WRITE_FAILED:
|
||||
log("Failed to write host cache to temporary file "
|
||||
"%s and rename it to %s" % (tmpname, CACHEFILE))
|
||||
CACHE_WRITE_FAILED = True
|
||||
|
||||
try:
|
||||
os.unlink(tmpname)
|
||||
except BaseException:
|
||||
@ -47,25 +58,34 @@ def write_host_cache():
|
||||
|
||||
|
||||
def read_host_cache():
|
||||
"""If possible, read the cache file from disk to populate hosts that
|
||||
were found in a previous sshuttle run."""
|
||||
try:
|
||||
f = open(CACHEFILE)
|
||||
except IOError:
|
||||
except (OSError, IOError):
|
||||
_, e = sys.exc_info()[:2]
|
||||
if e.errno == errno.ENOENT:
|
||||
return
|
||||
else:
|
||||
raise
|
||||
log("Failed to read existing host cache file %s on remote host"
|
||||
% CACHEFILE)
|
||||
return
|
||||
for line in f:
|
||||
words = line.strip().split(',')
|
||||
if len(words) == 2:
|
||||
(name, ip) = words
|
||||
name = re.sub(r'[^-\w\.]', '-', name).strip()
|
||||
# Remove characters that shouldn't be in IP
|
||||
ip = re.sub(r'[^0-9.]', '', ip).strip()
|
||||
if name and ip:
|
||||
found_host(name, ip)
|
||||
|
||||
|
||||
def found_host(name, ip):
|
||||
"""The provided name maps to the given IP. Add the host to the
|
||||
hostnames list, send the host to the sshuttle client via
|
||||
stdout, and write the host to the cache file.
|
||||
"""
|
||||
hostname = re.sub(r'\..*', '', name)
|
||||
hostname = re.sub(r'[^-\w\.]', '_', hostname)
|
||||
if (ip.startswith('127.') or ip.startswith('255.') or
|
||||
@ -84,29 +104,37 @@ def found_host(name, ip):
|
||||
|
||||
|
||||
def _check_etc_hosts():
|
||||
debug2(' > hosts')
|
||||
for line in open('/etc/hosts'):
|
||||
line = re.sub(r'#.*', '', line)
|
||||
"""If possible, read /etc/hosts to find hosts."""
|
||||
filename = '/etc/hosts'
|
||||
debug2(' > Reading %s on remote host' % filename)
|
||||
try:
|
||||
for line in open(filename):
|
||||
line = re.sub(r'#.*', '', line) # remove comments
|
||||
words = line.strip().split()
|
||||
if not words:
|
||||
continue
|
||||
ip = words[0]
|
||||
names = words[1:]
|
||||
if _is_ip(ip):
|
||||
names = words[1:]
|
||||
debug3('< %s %r' % (ip, names))
|
||||
for n in names:
|
||||
check_host(n)
|
||||
found_host(n, ip)
|
||||
except (OSError, IOError):
|
||||
debug1("Failed to read %s on remote host" % filename)
|
||||
|
||||
|
||||
def _check_revdns(ip):
|
||||
"""Use reverse DNS to try to get hostnames from an IP addresses."""
|
||||
debug2(' > rev: %s' % ip)
|
||||
try:
|
||||
r = socket.gethostbyaddr(ip)
|
||||
debug3('< %s' % r[0])
|
||||
check_host(r[0])
|
||||
found_host(r[0], ip)
|
||||
except (socket.herror, UnicodeError):
|
||||
except (OSError, socket.error, UnicodeError):
|
||||
# This case is expected to occur regularly.
|
||||
#debug3('< %s gethostbyaddr failed on remote host' % ip)
|
||||
pass
|
||||
|
||||
|
||||
@ -134,7 +162,14 @@ def _check_netstat():
|
||||
log('%r failed: %r' % (argv, e))
|
||||
return
|
||||
|
||||
# The same IPs may appear multiple times. Consolidate them so the
|
||||
# debug message doesn't print the same IP repeatedly.
|
||||
ip_list = []
|
||||
for ip in re.findall(r'\d+\.\d+\.\d+\.\d+', content):
|
||||
if ip not in ip_list:
|
||||
ip_list.append(ip)
|
||||
|
||||
for ip in sorted(ip_list):
|
||||
debug3('< %s' % ip)
|
||||
check_host(ip)
|
||||
|
||||
@ -179,13 +214,19 @@ def hw_main(seed_hosts, auto_hosts):
|
||||
|
||||
while 1:
|
||||
now = time.time()
|
||||
# For each item in the queue
|
||||
for t, last_polled in list(queue.items()):
|
||||
(op, args) = t
|
||||
if not _stdin_still_ok(0):
|
||||
break
|
||||
|
||||
# Determine if we need to run.
|
||||
maxtime = POLL_TIME
|
||||
# netstat runs more often than other jobs
|
||||
if op == _check_netstat:
|
||||
maxtime = NETSTAT_POLL_TIME
|
||||
|
||||
# Check if this jobs needs to run.
|
||||
if now - last_polled > maxtime:
|
||||
queue[t] = time.time()
|
||||
op(*args)
|
||||
@ -195,5 +236,5 @@ def hw_main(seed_hosts, auto_hosts):
|
||||
break
|
||||
|
||||
# FIXME: use a smarter timeout based on oldest last_polled
|
||||
if not _stdin_still_ok(1):
|
||||
if not _stdin_still_ok(1): # sleeps for up to 1 second
|
||||
break
|
||||
|
||||
Loading…
Reference in New Issue
Block a user