Add a --exclude option for excluding subnets from routing.

Also, add 127.0.0.0/8 to the default list of excludes.  If you want to route
0/0, you almost certainly *don't* want to route localhost to the remote ssh
server's localhost!

Thanks to Edward for the suggestion.

README.md

@@ -161,3 +161,6 @@ later.  You're welcome.
 --
 Avery Pennarun <apenwarr@gmail.com>
 
+Mailing list:
+   Subscribe by sending a message to <sshuttle+subscribe@googlegroups.com>
+   List archives are at: http://groups.google.com/group/sshuttle

assembler.py

@@ -7,7 +7,7 @@ while 1:
     if name:
         nbytes = int(sys.stdin.readline())
         if verbosity >= 2:
-            sys.stderr.write('remote assembling %r (%d bytes)\n'
+            sys.stderr.write('server: assembling %r (%d bytes)\n'
                              % (name, nbytes))
         content = z.decompress(sys.stdin.read(nbytes))
         exec compile(content, name, "exec")

client.py

@@ -1,4 +1,4 @@
-import struct, socket, select, subprocess, errno
+import struct, socket, select, subprocess, errno, re
 import helpers, ssnet, ssh
 from ssnet import SockWrapper, Handler, Proxy, Mux, MuxWrapper
 from helpers import *
@@ -20,13 +20,14 @@ def original_dst(sock):
 
 
 class FirewallClient:
-    def __init__(self, port, subnets):
+    def __init__(self, port, subnets_include, subnets_exclude):
         self.port = port
-        self.subnets = subnets
-        subnets_str = ['%s/%d' % (ip,width) for ip,width in subnets]
+        self.auto_nets = []
+        self.subnets_include = subnets_include
+        self.subnets_exclude = subnets_exclude
         argvbase = ([sys.argv[0]] +
                     ['-v'] * (helpers.verbose or 0) +
-                    ['--firewall', str(port)] + subnets_str)
+                    ['--firewall', str(port)])
         argv_tries = [
             ['sudo'] + argvbase,
             ['su', '-c', ' '.join(argvbase)],
@@ -66,6 +67,11 @@ class FirewallClient:
             raise Fatal('%r returned %d' % (self.argv, rv))
 
     def start(self):
+        self.pfile.write('ROUTES\n')
+        for (ip,width) in self.subnets_include+self.auto_nets:
+            self.pfile.write('%d,0,%s\n' % (width, ip))
+        for (ip,width) in self.subnets_exclude:
+            self.pfile.write('%d,1,%s\n' % (width, ip))
         self.pfile.write('GO\n')
         self.pfile.flush()
         line = self.pfile.readline()
@@ -73,6 +79,12 @@ class FirewallClient:
         if line != 'STARTED\n':
             raise Fatal('%r expected STARTED, got %r' % (self.argv, line))
 
+    def sethostip(self, hostname, ip):
+        assert(not re.search(r'[^-\w]', hostname))
+        assert(not re.search(r'[^0-9.]', ip))
+        self.pfile.write('HOST %s,%s\n' % (hostname, ip))
+        self.pfile.flush()
+
     def done(self):
         self.pfile.close()
         rv = self.p.wait()
@@ -80,13 +92,14 @@ class FirewallClient:
             raise Fatal('cleanup: %r returned %d' % (self.argv, rv))
 
 
-def _main(listener, fw, use_server, remotename):
+def _main(listener, fw, use_server, remotename, seed_hosts, auto_nets):
     handlers = []
     if use_server:
         if helpers.verbose >= 1:
             helpers.logprefix = 'c : '
         else:
             helpers.logprefix = 'client: '
+        debug1('connecting to server...\n')
         (serverproc, serversock) = ssh.connect(remotename)
         mux = Mux(serversock, serversock)
         handlers.append(mux)
@@ -101,10 +114,32 @@ def _main(listener, fw, use_server, remotename):
         if initstring != expected:
             raise Fatal('expected server init string %r; got %r'
                             % (expected, initstring))
+        debug1('connected.\n')
 
-    # we definitely want to do this *after* starting ssh, or we might end
-    # up intercepting the ssh connection!
-    fw.start()
+    def onroutes(routestr):
+        if auto_nets:
+            for line in routestr.strip().split('\n'):
+                (ip,width) = line.split(',', 1)
+                fw.auto_nets.append((ip,int(width)))
+
+        # we definitely want to do this *after* starting ssh, or we might end
+        # up intercepting the ssh connection!
+        #
+        # Moreover, now that we have the --auto-nets option, we have to wait
+        # for the server to send us that message anyway.  Even if we haven't
+        # set --auto-nets, we might as well wait for the message first, then
+        # ignore its contents.
+        mux.got_routes = None
+        fw.start()
+    mux.got_routes = onroutes
+
+    def onhostlist(hostlist):
+        debug2('got host list: %r\n' % hostlist)
+        for line in hostlist.strip().split():
+            if line:
+                name,ip = line.split(',', 1)
+                fw.sethostip(name, ip)
+    mux.got_host_list = onhostlist
 
     def onaccept():
         sock,srcip = listener.accept()
@@ -123,6 +158,10 @@ def _main(listener, fw, use_server, remotename):
             outwrap = ssnet.connect_dst(dstip[0], dstip[1])
         handlers.append(Proxy(SockWrapper(sock, sock), outwrap))
     handlers.append(Handler([listener], onaccept))
+
+    if seed_hosts != None:
+        debug1('seed_hosts: %r\n' % seed_hosts)
+        mux.send(0, ssnet.CMD_HOST_REQ, '\n'.join(seed_hosts))
     
     while 1:
         if use_server:
@@ -149,7 +188,8 @@ def _main(listener, fw, use_server, remotename):
             mux.check_fullness()
 
 
-def main(listenip, use_server, remotename, subnets):
+def main(listenip, use_server, remotename, seed_hosts, auto_nets,
+         subnets_include, subnets_exclude):
     debug1('Starting sshuttle proxy.\n')
     listener = socket.socket()
     listener.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
@@ -176,9 +216,10 @@ def main(listenip, use_server, remotename, subnets):
     listenip = listener.getsockname()
     debug1('Listening on %r.\n' % (listenip,))
 
-    fw = FirewallClient(listenip[1], subnets)
+    fw = FirewallClient(listenip[1], subnets_include, subnets_exclude)
     
     try:
-        return _main(listener, fw, use_server, remotename)
+        return _main(listener, fw, use_server, remotename,
+                     seed_hosts, auto_nets)
     finally:
         fw.done()

firewall.py

@@ -1,4 +1,4 @@
-import subprocess, re
+import subprocess, re, errno
 import helpers
 from helpers import *
 
@@ -43,14 +43,23 @@ def do_iptables(port, subnets):
         ipt('-I', 'OUTPUT', '1', '-j', chain)
         ipt('-I', 'PREROUTING', '1', '-j', chain)
 
-        # create new subnet entries
-        for snet,swidth in subnets:
-            ipt('-A', chain, '-j', 'REDIRECT',
-                '--dest', '%s/%s' % (snet,swidth),
-                '-p', 'tcp',
-                '--to-ports', str(port),
-                '-m', 'ttl', '!', '--ttl', '42'  # to prevent infinite loops
-                )
+        # create new subnet entries.  Note that we're sorting in a very
+        # particular order: we need to go from most-specific (largest swidth)
+        # to least-specific, and at any given level of specificity, we want
+        # excludes to come first.  That's why the columns are in such a non-
+        # intuitive order.
+        for swidth,sexclude,snet in sorted(subnets, reverse=True):
+            if sexclude:
+                ipt('-A', chain, '-j', 'RETURN',
+                    '--dest', '%s/%s' % (snet,swidth),
+                    '-p', 'tcp')
+            else:
+                ipt('-A', chain, '-j', 'REDIRECT',
+                    '--dest', '%s/%s' % (snet,swidth),
+                    '-p', 'tcp',
+                    '--to-ports', str(port),
+                    '-m', 'ttl', '!', '--ttl', '42'  # to prevent infinite loops
+                    )
 
 
 def ipfw_rule_exists(n):
@@ -58,7 +67,7 @@ def ipfw_rule_exists(n):
     p = subprocess.Popen(argv, stdout = subprocess.PIPE)
     for line in p.stdout:
         if line.startswith('%05d ' % n):
-            if line[5:].find('ipttl 42') < 0:
+            if line.find('ipttl 42') < 0 and line.find('established') < 0:
                 raise Fatal('non-sshuttle ipfw rule #%d already exists!' % n)
             return True
     rv = p.wait()
@@ -103,6 +112,7 @@ def ipfw(*args):
 
 def do_ipfw(port, subnets):
     sport = str(port)
+    xsport = str(port+1)
 
     # cleanup any existing rules
     if ipfw_rule_exists(port):
@@ -115,13 +125,21 @@ def do_ipfw(port, subnets):
     if subnets:
         sysctl_set('net.inet.ip.fw.enable', 1)
         sysctl_set('net.inet.ip.forwarding', 1)
+
+        ipfw('add', sport, 'accept', 'ip',
+             'from', 'any', 'to', 'any', 'established')
         
         # create new subnet entries
-        for snet,swidth in subnets:
-            ipfw('add', sport, 'fwd', '127.0.0.1,%d' % port,
-                 'log', 'tcp',
-                 'from', 'any', 'to', '%s/%s' % (snet,swidth),
-                 'not', 'ipttl', '42')
+        for swidth,sexclude,snet in sorted(subnets, reverse=True):
+            if sexclude:
+                ipfw('add', sport, 'skipto', xsport,
+                     'log', 'tcp',
+                     'from', 'any', 'to', '%s/%s' % (snet,swidth))
+            else:
+                ipfw('add', sport, 'fwd', '127.0.0.1,%d' % port,
+                     'log', 'tcp',
+                     'from', 'any', 'to', '%s/%s' % (snet,swidth),
+                     'not', 'ipttl', '42')
 
 
 def program_exists(name):
@@ -131,6 +149,47 @@ def program_exists(name):
         if os.path.exists(fn):
             return not os.path.isdir(fn) and os.access(fn, os.X_OK)
 
+hostmap = {}
+def rewrite_etc_hosts(port):
+    HOSTSFILE='/etc/hosts'
+    BAKFILE='%s.sbak' % HOSTSFILE
+    APPEND='# sshuttle-firewall-%d AUTOCREATED' % port
+    old_content = ''
+    st = None
+    try:
+        old_content = open(HOSTSFILE).read()
+        st = os.stat(HOSTSFILE)
+    except IOError, e:
+        if e.errno == errno.ENOENT:
+            pass
+        else:
+            raise
+    if old_content.strip() and not os.path.exists(BAKFILE):
+        os.link(HOSTSFILE, BAKFILE)
+    tmpname = "%s.%d.tmp" % (HOSTSFILE, port)
+    f = open(tmpname, 'w')
+    for line in old_content.rstrip().split('\n'):
+        if line.find(APPEND) >= 0:
+            continue
+        f.write('%s\n' % line)
+    for (name,ip) in sorted(hostmap.items()):
+        f.write('%-30s %s\n' % ('%s %s' % (ip,name), APPEND))
+    f.close()
+
+    if st:
+        os.chown(tmpname, st.st_uid, st.st_gid)
+        os.chmod(tmpname, st.st_mode)
+    else:
+        os.chown(tmpname, 0, 0)
+        os.chmod(tmpname, 0644)
+    os.rename(tmpname, HOSTSFILE)
+
+
+def restore_etc_hosts(port):
+    global hostmap
+    hostmap = {}
+    rewrite_etc_hosts(port)
+
 
 # This is some voodoo for setting up the kernel's transparent
 # proxying stuff.  If subnets is empty, we just delete our sshuttle rules;
@@ -140,7 +199,7 @@ def program_exists(name):
 # exit.  In case that fails, it's not the end of the world; future runs will
 # supercede it in the transproxy list, at least, so the leftover rules
 # are hopefully harmless.
-def main(port, subnets):
+def main(port):
     assert(port > 0)
     assert(port <= 65535)
 
@@ -173,8 +232,22 @@ def main(port, subnets):
     line = sys.stdin.readline(128)
     if not line:
         return  # parent died; nothing to do
-    if line != 'GO\n':
-        raise Fatal('firewall: expected GO but got %r' % line)
+
+    subnets = []
+    if line != 'ROUTES\n':
+        raise Fatal('firewall: expected ROUTES but got %r' % line)
+    while 1:
+        line = sys.stdin.readline(128)
+        if not line:
+            raise Fatal('firewall: expected route but got %r' % line)
+        elif line == 'GO\n':
+            break
+        try:
+            (width,exclude,ip) = line.strip().split(',', 2)
+        except:
+            raise Fatal('firewall: expected route or GO but got %r' % line)
+        subnets.append((int(width), bool(int(exclude)), ip))
+        
     try:
         if line:
             debug1('firewall manager: starting transproxy.\n')
@@ -183,20 +256,28 @@ def main(port, subnets):
         
         try:
             sys.stdout.flush()
-            
-            # Now we wait until EOF or any other kind of exception.  We need
-            # to stay running so that we don't need a *second* password
-            # authentication at shutdown time - that cleanup is important!
-            while sys.stdin.readline(128):
-                pass
         except IOError:
             # the parent process died for some reason; he's surely been loud
             # enough, so no reason to report another error
             return
 
+        # Now we wait until EOF or any other kind of exception.  We need
+        # to stay running so that we don't need a *second* password
+        # authentication at shutdown time - that cleanup is important!
+        while 1:
+            line = sys.stdin.readline(128)
+            if line.startswith('HOST '):
+                (name,ip) = line[5:].strip().split(',', 1)
+                hostmap[name] = ip
+                rewrite_etc_hosts(port)
+            elif line:
+                raise Fatal('expected EOF, got %r' % line)
+            else:
+                break
     finally:
         try:
             debug1('firewall manager: undoing changes.\n')
         except:
             pass
         do_it(port, [])
+        restore_etc_hosts(port)

helpers.py

@@ -4,9 +4,14 @@ logprefix = ''
 verbose = 0
 
 def log(s):
-    sys.stdout.flush()
-    sys.stderr.write(logprefix + s)
-    sys.stderr.flush()
+    try:
+        sys.stdout.flush()
+        sys.stderr.write(logprefix + s)
+        sys.stderr.flush()
+    except IOError:
+        # this could happen if stderr gets forcibly disconnected, eg. because
+        # our tty closes.  That sucks, but it's no reason to abort the program.
+        pass
 
 def debug1(s):
     if verbose >= 1:
@@ -16,6 +21,10 @@ def debug2(s):
     if verbose >= 2:
         log(s)
 
+def debug3(s):
+    if verbose >= 3:
+        log(s)
+
 
 class Fatal(Exception):
     pass

hostwatch.py

@@ -0,0 +1,276 @@
+import subprocess, time, socket, re, select
+if not globals().get('skip_imports'):
+    import helpers
+    from helpers import *
+
+POLL_TIME = 60*15
+NETSTAT_POLL_TIME = 30
+CACHEFILE=os.path.expanduser('~/.sshuttle.hosts')
+
+
+_nmb_ok = True
+_smb_ok = True
+hostnames = {}
+queue = {}
+null = open('/dev/null', 'rb+')
+
+
+def _is_ip(s):
+    return re.match(r'\d+\.\d+\.\d+\.\d+$', s)
+
+
+def write_host_cache():
+    tmpname = '%s.%d.tmp' % (CACHEFILE, os.getpid())
+    try:
+        f = open(tmpname, 'wb')
+        for name,ip in sorted(hostnames.items()):
+            f.write('%s,%s\n' % (name, ip))
+        f.close()
+        os.rename(tmpname, CACHEFILE)
+    finally:
+        try:
+            os.unlink(tmpname)
+        except:
+            pass
+
+
+def read_host_cache():
+    try:
+        f = open(CACHEFILE)
+    except IOError, e:
+        if e.errno == errno.ENOENT:
+            return
+        else:
+            raise
+    for line in f:
+        words = line.strip().split(',')
+        if len(words) == 2:
+            (name,ip) = words
+            name = re.sub(r'[^-\w]', '-', name).strip()
+            ip = re.sub(r'[^0-9.]', '', ip).strip()
+            if name and ip:
+                found_host(name, ip)
+                
+
+def found_host(hostname, ip):
+    hostname = re.sub(r'\..*', '', hostname)
+    hostname = re.sub(r'[^-\w]', '_', hostname)
+    if (ip.startswith('127.') or ip.startswith('255.') 
+        or hostname == 'localhost'):
+        return
+    oldip = hostnames.get(hostname)
+    if oldip != ip:
+        hostnames[hostname] = ip
+        debug1('Found: %s: %s\n' % (hostname, ip))
+        sys.stdout.write('%s,%s\n' % (hostname, ip))
+        write_host_cache()
+
+
+def _check_etc_hosts():
+    debug2(' > hosts\n')
+    for line in open('/etc/hosts'):
+        line = re.sub(r'#.*', '', line)
+        words = line.strip().split()
+        if not words:
+            continue
+        ip = words[0]
+        names = words[1:]
+        if _is_ip(ip):
+            debug3('<    %s %r\n' % (ip, names))
+            for n in names:
+                check_host(n)
+                found_host(n, ip)
+
+
+def _check_revdns(ip):
+    debug2(' > rev: %s\n' % ip)
+    try:
+        r = socket.gethostbyaddr(ip)
+        debug3('<    %s\n' % r[0])
+        check_host(r[0])
+        found_host(r[0], ip)
+    except socket.herror, e:
+        pass
+
+
+def _check_dns(hostname):
+    debug2(' > dns: %s\n' % hostname)
+    try:
+        ip = socket.gethostbyname(hostname)
+        debug3('<    %s\n' % ip)
+        check_host(ip)
+        found_host(hostname, ip)
+    except socket.gaierror, e:
+        pass
+
+
+def _check_netstat():
+    debug2(' > netstat\n')
+    argv = ['netstat', '-n']
+    try:
+        p = subprocess.Popen(argv, stdout=subprocess.PIPE, stderr=null)
+        content = p.stdout.read()
+        p.wait()
+    except OSError, e:
+        log('%r failed: %r\n' % (argv, e))
+        return
+
+    for ip in re.findall(r'\d+\.\d+\.\d+\.\d+', content):
+        debug3('<    %s\n' % ip)
+        check_host(ip)
+        
+
+def _check_smb(hostname):
+    return
+    global _smb_ok
+    if not _smb_ok:
+        return
+    argv = ['smbclient', '-U', '%', '-L', hostname]
+    debug2(' > smb: %s\n' % hostname)
+    try:
+        p = subprocess.Popen(argv, stdout=subprocess.PIPE, stderr=null)
+        lines = p.stdout.readlines()
+        p.wait()
+    except OSError, e:
+        log('%r failed: %r\n' % (argv, e))
+        _smb_ok = False
+        return
+
+    lines.reverse()
+
+    # junk at top
+    while lines:
+        line = lines.pop().strip()
+        if re.match(r'Server\s+', line):
+            break
+
+    # server list section:
+    #    Server   Comment
+    #    ------   -------
+    while lines:
+        line = lines.pop().strip()
+        if not line or re.match(r'-+\s+-+', line):
+            continue
+        if re.match(r'Workgroup\s+Master', line):
+            break
+        words = line.split()
+        hostname = words[0].lower()
+        debug3('<    %s\n' % hostname)
+        check_host(hostname)
+
+    # workgroup list section:
+    #   Workgroup  Master
+    #   ---------  ------
+    while lines:
+        line = lines.pop().strip()
+        if re.match(r'-+\s+', line):
+            continue
+        if not line:
+            break
+        words = line.split()
+        (workgroup, hostname) = (words[0].lower(), words[1].lower())
+        debug3('<    group(%s) -> %s\n' % (workgroup, hostname))
+        check_host(hostname)
+        check_workgroup(workgroup)
+
+    if lines:
+        assert(0)
+
+
+def _check_nmb(hostname, is_workgroup, is_master):
+    return
+    global _nmb_ok
+    if not _nmb_ok:
+        return
+    argv = ['nmblookup'] + ['-M']*is_master + ['--', hostname]
+    debug2(' > n%d%d: %s\n' % (is_workgroup, is_master, hostname))
+    try:
+        p = subprocess.Popen(argv, stdout=subprocess.PIPE, stderr=null)
+        lines = p.stdout.readlines()
+        rv = p.wait()
+    except OSError, e:
+        log('%r failed: %r\n' % (argv, e))
+        _nmb_ok = False
+        return
+    if rv:
+        log('%r returned %d\n' % (argv, rv))
+        return
+    for line in lines:
+        m = re.match(r'(\d+\.\d+\.\d+\.\d+) (\w+)<\w\w>\n', line)
+        if m:
+            g = m.groups()
+            (ip, name) = (g[0], g[1].lower())
+            debug3('<    %s -> %s\n' % (name, ip))
+            if is_workgroup:
+                _enqueue(_check_smb, ip)
+            else:
+                found_host(name, ip)
+                check_host(name)
+
+
+def check_host(hostname):
+    if _is_ip(hostname):
+        _enqueue(_check_revdns, hostname)
+    else:
+        _enqueue(_check_dns, hostname)
+    _enqueue(_check_smb, hostname)
+    _enqueue(_check_nmb, hostname, False, False)
+
+
+def check_workgroup(hostname):
+    _enqueue(_check_nmb, hostname, True, False)
+    _enqueue(_check_nmb, hostname, True, True)
+
+
+def _enqueue(op, *args):
+    t = (op,args)
+    if queue.get(t) == None:
+        queue[t] = 0
+
+
+def _stdin_still_ok(timeout):
+    r,w,x = select.select([sys.stdin.fileno()], [], [], timeout)
+    if r:
+        b = os.read(sys.stdin.fileno(), 4096)
+        if not b:
+            return False
+    return True
+
+
+def hw_main(seed_hosts):
+    if helpers.verbose >= 2:
+        helpers.logprefix = 'HH: '
+    else:
+        helpers.logprefix = 'hostwatch: '
+
+    read_host_cache()
+        
+    _enqueue(_check_etc_hosts)
+    _enqueue(_check_netstat)
+    check_host('localhost')
+    check_host(socket.gethostname())
+    check_workgroup('workgroup')
+    check_workgroup('-')
+    for h in seed_hosts:
+        check_host(h)
+
+    while 1:
+        now = time.time()
+        for t,last_polled in queue.items():
+            (op,args) = t
+            if not _stdin_still_ok(0):
+                break
+            maxtime = POLL_TIME
+            if op == _check_netstat:
+                maxtime = NETSTAT_POLL_TIME
+            if now - last_polled > maxtime:
+                queue[t] = time.time()
+                op(*args)
+            try:
+                sys.stdout.flush()
+            except IOError:
+                break
+                
+        # FIXME: use a smarter timeout based on oldest last_polled
+        if not _stdin_still_ok(1):
+            break

main.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 import sys, os, re
-import helpers, options, client, server, firewall
+import helpers, options, client, server, firewall, hostwatch
 from helpers import *
 
 
@@ -50,11 +50,16 @@ sshuttle --firewall <port> <subnets...>
 sshuttle --server
 --
 l,listen=  transproxy to this ip address and port number [default=0]
+H,auto-hosts scan for remote hostnames and update local /etc/hosts
+N,auto-nets  automatically determine subnets to route
 r,remote=  ssh hostname (and optional username) of remote sshuttle server
+x,exclude= exclude this subnet (can be used more than once)
 v,verbose  increase debug message verbosity
+seed-hosts= with -H, use these hostnames for initial scan (comma-separated)
 noserver   don't use a separate server process (mostly for debugging)
 server     [internal use only]
 firewall   [internal use only]
+hostwatch  [internal use only]
 """
 o = options.Options('sshuttle', optspec)
 (opt, flags, extra) = o.parse(sys.argv[1:])
@@ -63,22 +68,41 @@ helpers.verbose = opt.verbose
 
 try:
     if opt.server:
+        if len(extra) != 0:
+            o.fatal('no arguments expected')
         sys.exit(server.main())
     elif opt.firewall:
-        if len(extra) < 1:
-            o.fatal('at least one argument expected')
-        sys.exit(firewall.main(int(extra[0]),
-                               parse_subnets(extra[1:])))
+        if len(extra) != 1:
+            o.fatal('exactly one argument expected')
+        sys.exit(firewall.main(int(extra[0])))
+    elif opt.hostwatch:
+        sys.exit(hostwatch.hw_main(extra))
     else:
-        if len(extra) < 1:
-            o.fatal('at least one subnet expected')
+        if len(extra) < 1 and not opt.auto_nets:
+            o.fatal('at least one subnet (or -N) expected')
+        includes = extra
+        excludes = ['127.0.0.0/8']
+        for k,v in flags:
+            if k in ('-x','--exclude'):
+                excludes.append(v)
         remotename = opt.remote
         if remotename == '' or remotename == '-':
             remotename = None
+        if opt.seed_hosts and not opt.auto_hosts:
+            o.fatal('--seed-hosts only works if you also use -H')
+        if opt.seed_hosts:
+            sh = re.split(r'[\s,]+', (opt.seed_hosts or "").strip())
+        elif opt.auto_hosts:
+            sh = []
+        else:
+            sh = None
         sys.exit(client.main(parse_ipport(opt.listen or '0.0.0.0:0'),
                              not opt.noserver,
                              remotename,
-                             parse_subnets(extra)))
+                             sh,
+                             opt.auto_nets,
+                             parse_subnets(includes),
+                             parse_subnets(excludes)))
 except Fatal, e:
     log('fatal: %s\n' % e)
     sys.exit(99)

server.py

@@ -1,15 +1,115 @@
-import struct, socket, select
+import re, struct, socket, select, subprocess, traceback
 if not globals().get('skip_imports'):
-    import ssnet, helpers
+    import ssnet, helpers, hostwatch
     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] & (1<<i):
+            return 32-i
+    return 0
+
+
+def _list_routes():
+    argv = ['netstat', '-rn']
+    p = subprocess.Popen(argv, stdout=subprocess.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] & (((1<<width)-1) << (32-width))
+        routes.append((socket.inet_ntoa(struct.pack('!I', ip)), width))
+    rv = p.wait()
+    if rv != 0:
+        raise Fatal('%r returned %d' % (argv, rv))
+    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
+
+
 def main():
     if helpers.verbose >= 1:
         helpers.logprefix = ' s: '
     else:
         helpers.logprefix = 'server: '
+
+    routes = list(list_routes())
+    debug1('available routes:\n')
+    for r in routes:
+        debug1('  %s/%d\n' % r)
         
     # synchronization header
     sys.stdout.write('SSHUTTLE0001')
@@ -21,16 +121,40 @@ def main():
               socket.fromfd(sys.stdout.fileno(),
                             socket.AF_INET, socket.SOCK_STREAM))
     handlers.append(mux)
+    routepkt = ''.join('%s,%d\n' % r
+                       for r in routes)
+    mux.send(0, ssnet.CMD_ROUTES, routepkt)
+
+    hw = Hostwatch()
+
+    def hostwatch_ready():
+        assert(hw.pid)
+        content = hw.sock.recv(4096)
+        if content:
+            mux.send(0, ssnet.CMD_HOST_LIST, content)
+        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
 
     while mux.ok:
+        if hw.pid:
+            (rpid, rv) = os.waitpid(hw.pid, os.WNOHANG)
+            if rpid:
+                raise Fatal('hostwatch exited unexpectedly: code 0x%04x\n' % rv)
+        
         r = set()
         w = set()
         x = set()

ssh.py

@@ -5,8 +5,12 @@ from helpers import *
 
 def readfile(name):
     basedir = os.path.dirname(os.path.abspath(sys.argv[0]))
-    fullname = os.path.join(basedir, name)
-    return open(fullname, 'rb').read()
+    path = [basedir] + sys.path
+    for d in path:
+        fullname = os.path.join(d, name)
+        if os.path.exists(fullname):
+            return open(fullname, 'rb').read()
+    raise Exception("can't find file %r in any of %r" % (name, path))
 
 
 def empackage(z, filename):
@@ -30,6 +34,7 @@ def connect(rhostport):
     content = readfile('assembler.py')
     content2 = (empackage(z, 'helpers.py') +
                 empackage(z, 'ssnet.py') +
+                empackage(z, 'hostwatch.py') +
                 empackage(z, 'server.py') +
                 "\n")
     

ssnet.py

@@ -12,6 +12,9 @@ CMD_CONNECT = 0x4203
 CMD_CLOSE = 0x4204
 CMD_EOF = 0x4205
 CMD_DATA = 0x4206
+CMD_ROUTES = 0x4207
+CMD_HOST_REQ = 0x4208
+CMD_HOST_LIST = 0x4209
 
 cmd_to_name = {
     CMD_EXIT: 'EXIT',
@@ -21,6 +24,9 @@ cmd_to_name = {
     CMD_CLOSE: 'CLOSE',
     CMD_EOF: 'EOF',
     CMD_DATA: 'DATA',
+    CMD_ROUTES: 'ROUTES',
+    CMD_HOST_REQ: 'HOST_REQ',
+    CMD_HOST_LIST: 'HOST_LIST',
 }
     
 
@@ -83,7 +89,9 @@ class SockWrapper:
             elif e.args[0] == errno.EISCONN:
                 # connected successfully (BSD)
                 self.connect_to = None
-            elif e.args[0] in [errno.ECONNREFUSED, errno.ETIMEDOUT]:
+            elif e.args[0] in [errno.ECONNREFUSED, errno.ETIMEDOUT,
+                               errno.EHOSTUNREACH, errno.ENETUNREACH,
+                               errno.EACCES, errno.EPERM]:
                 # a "normal" kind of error
                 self.connect_to = None
                 self.seterr(e)
@@ -218,7 +226,8 @@ class Mux(Handler):
         Handler.__init__(self, [rsock, wsock])
         self.rsock = rsock
         self.wsock = wsock
-        self.new_channel = None
+        self.new_channel = self.got_routes = None
+        self.got_host_req = self.got_host_list = None
         self.channels = {}
         self.chani = 0
         self.want = 0
@@ -257,12 +266,13 @@ class Mux(Handler):
         p = struct.pack('!ccHHH', 'S', 'S', channel, cmd, len(data)) + data
         self.outbuf.append(p)
         debug2(' > channel=%d cmd=%s len=%d (fullness=%d)\n'
-               % (channel, cmd_to_name[cmd], len(data), self.fullness))
+               % (channel, cmd_to_name.get(cmd,hex(cmd)),
+                  len(data), self.fullness))
         self.fullness += len(data)
 
     def got_packet(self, channel, cmd, data):
         debug2('<  channel=%d cmd=%s len=%d\n' 
-               % (channel, cmd_to_name[cmd], len(data)))
+               % (channel, cmd_to_name.get(cmd,hex(cmd)), len(data)))
         if cmd == CMD_PING:
             self.send(0, CMD_PONG, data)
         elif cmd == CMD_PONG:
@@ -275,6 +285,21 @@ class Mux(Handler):
             assert(not self.channels.get(channel))
             if self.new_channel:
                 self.new_channel(channel, data)
+        elif cmd == CMD_ROUTES:
+            if self.got_routes:
+                self.got_routes(data)
+            else:
+                raise Exception('got CMD_ROUTES without got_routes?')
+        elif cmd == CMD_HOST_REQ:
+            if self.got_host_req:
+                self.got_host_req(data)
+            else:
+                raise Exception('got CMD_HOST_REQ without got_host_req?')
+        elif cmd == CMD_HOST_LIST:
+            if self.got_host_list:
+                self.got_host_list(data)
+            else:
+                raise Exception('got CMD_HOST_LIST without got_host_list?')
         else:
             callback = self.channels[channel]
             callback(cmd, data)