Fixes in netstat parsing... back !

Hi all,

I'm back with the "netmask bug" ;-) :

Under (Open)BSD, I have this bug when reading the system routes if there 
are netmasks different from /0, /8, /16, /24, and /32.

The same bug may be shown under Linux :


lalet@euclide ~/work/python/scapy $ ./scapy.py.orig
Welcome to Scapy (1.0.0.47beta)
>>> conf.route.add(net="10.1.0.0/22",gw="172.16.0.3")
>>> conf.route
Network       Netmask         Gateway         Iface    Output IP
                                  [...]
10.1.0.0      255.255.63.0    172.16.0.3      eth0     172.16.0.7


The netmask is 255.255.63.0, which makes no sense.

The patch attached fixed this issue, and also removes the useless routes 
present in "netstat -rn" output (one for each IP/MAC association in the 
cache, at least under OpenBSD).

The new itom(x) function computes the netmask value (as stored in scapy 
routing table) from the number of bits to 1 (i.e., the value after the '/').

Unlike the previous patch I've posted here for the same bug, as I've had 
a little more time, this one fixes this bug everywhere (unless I've 
missed something, of course). So even under Linux, we now have:


lalet@euclide ~/work/python/scapy $ ./scapy.py
Welcome to Scapy (1.0.0.47beta)
>>> conf.route.add(net="10.1.0.0/22",gw="172.16.0.3")
>>> conf.route
Network       Netmask         Gateway         Iface    Output IP
                                  [...]
10.1.0.0      255.255.252.0   172.16.0.3      eth0     172.16.0.7


255.255.252.0 sounds better to me.

Pierre
--- scapy.py.orig       2005-10-06 15:04:08.000000000 +0200
+++ scapy.py    2005-10-08 13:39:55.000000000 +0200
@@ -1373,7 +1373,8 @@ def atol(x):
     return struct.unpack("I", ip)[0]
 def ltoa(x):
     return socket.inet_ntoa(struct.pack("I", x))
-
+def itom(x):
+    return socket.htonl((1L << x) - 1 << 32 - x)
 
 def do_graph(graph,type="svg",target="| display"):
     """do_graph(graph, type="svg",target="| display"):
@@ -1510,7 +1511,7 @@ class Route:
             dev,ifaddr,x = self.route(nhop)
         else:
             ifaddr = get_if_addr(dev)
-        return (atol(thenet),(1L<<msk)-1, gw, dev, ifaddr)
+        return (atol(thenet), itom(msk), gw, dev, ifaddr)
 
     def add(self, *args, **kargs):
         """Ex:
@@ -1529,7 +1530,7 @@ class Route:
              
     def ifchange(self, iff, addr):
         the_addr,the_msk = (addr.split("/")+["32"])[:2]
-        the_msk = (1L << int(the_msk))-1
+        the_msk = itom(int(the_msk))
         the_rawaddr, = struct.unpack("I",inet_aton(the_addr))
         the_net = the_rawaddr & the_msk
         
@@ -1556,7 +1557,7 @@ class Route:
         
     def ifadd(self, iff, addr):
         the_addr,the_msk = (addr.split("/")+["32"])[:2]
-        the_msk = (1L << int(the_msk))-1
+        the_msk = itom(int(the_msk))
         the_rawaddr, = struct.unpack("I",inet_aton(the_addr))
         the_net = the_rawaddr & the_msk
         self.routes.append((the_net,the_msk,'0.0.0.0',iff,the_addr))
@@ -1721,15 +1722,17 @@ if not LINUX:
                 dest,gw,fl,ref,use,mtu,netif = l.split()[:7]
             else:
                 dest,gw,fl,ref,use,netif = l.split()[:6]
+            if fl.find("Lc") >= 0:
+                continue
             if dest == "default":
                 dest = 0L
                 netmask = 0L
             else:
                 if "/" in dest:
                     dest,netmask = dest.split("/")
-                    netmask = (1L << int(netmask))-1
+                    netmask = itom(int(netmask))
                 else:
-                    netmask = (1L << ((dest.count(".")+1)*8))-1
+                    netmask = itom((dest.count(".") + 1) * 8)
                 dest += ".0"*(3-dest.count("."))
                 dest, = struct.unpack("I",inet_aton(dest))
             if not "G" in fl:

---------------------------------------------------------------------
Desinscription: envoyez un message a: scapy.ml-unsubscribe@xxxxxxxxxx
Pour obtenir de l'aide, ecrivez a: scapy.ml-help@xxxxxxxxxx