Fix MultipleTypeField default values handling

doc/scapy/build_dissect.rst

@@ -1071,7 +1071,6 @@ TCP/IP
     MACField
     DestMACField(MACField)
     SourceMACField(MACField)
-    ARPSourceMACField(MACField)
 
     ICMPTimeStampField
 

scapy/arch/windows/__init__.py

@@ -723,6 +723,8 @@ def reload(self):
             from scapy.arch.pcapdnet import load_winpcapy
             load_winpcapy()
         self.load()
+        # Reload conf.iface
+        conf.iface = get_working_if()
 
     def show(self, resolve_mac=True, print_result=True):
         """Print list of available network interfaces in human readable form"""

scapy/fields.py

@@ -275,31 +275,41 @@ def __init__(self, flds, dflt):
         self.dflt = dflt
         self.name = self.dflt.name
 
+    def _iterate_fields_cond(self, pkt, val, use_val):
+        """Internal function used by _find_fld_pkt & _find_fld_pkt_val"""
+        # Iterate through the fields
+        for fld, cond in self.flds:
+            if isinstance(cond, tuple):
+                if use_val:
+                    if cond[1](pkt, val):
+                        return fld
+                    continue
+                else:
+                    cond = cond[0]
+            if cond(pkt):
+                return fld
+        return self.dflt
+
     def _find_fld_pkt(self, pkt):
         """Given a Packet instance `pkt`, returns the Field subclass to be
 used. If you know the value to be set (e.g., in .addfield()), use
 ._find_fld_pkt_val() instead.
 
         """
-        for fld, cond in self.flds:
-            if isinstance(cond, tuple):
-                cond = cond[0]
-            if cond(pkt):
-                return fld
-        return self.dflt
+        return self._iterate_fields_cond(pkt, None, False)
 
     def _find_fld_pkt_val(self, pkt, val):
         """Given a Packet instance `pkt` and the value `val` to be set,
-returns the Field subclass to be used.
+returns the Field subclass to be used, and the updated `val` if necessary.
 
         """
-        for fld, cond in self.flds:
-            if isinstance(cond, tuple):
-                if cond[1](pkt, val):
-                    return fld
-            elif cond(pkt):
-                return fld
-        return self.dflt
+        fld = self._iterate_fields_cond(pkt, val, True)
+        # Default ? (in this case, let's make sure it's up-do-date)
+        dflts_pkt = pkt.default_fields
+        if val == dflts_pkt[self.name] and self.name not in pkt.fields:
+            dflts_pkt[self.name] = fld.default
+            val = fld.default
+        return fld, val
 
     def _find_fld(self):
         """Returns the Field subclass to be used, depending on the Packet
@@ -331,25 +341,32 @@ def getfield(self, pkt, s):
         return self._find_fld_pkt(pkt).getfield(pkt, s)
 
     def addfield(self, pkt, s, val):
-        return self._find_fld_pkt_val(pkt, val).addfield(pkt, s, val)
+        fld, val = self._find_fld_pkt_val(pkt, val)
+        return fld.addfield(pkt, s, val)
 
     def any2i(self, pkt, val):
-        return self._find_fld_pkt_val(pkt, val).any2i(pkt, val)
+        fld, val = self._find_fld_pkt_val(pkt, val)
+        return fld.any2i(pkt, val)
 
     def h2i(self, pkt, val):
-        return self._find_fld_pkt_val(pkt, val).h2i(pkt, val)
+        fld, val = self._find_fld_pkt_val(pkt, val)
+        return fld.h2i(pkt, val)
 
     def i2h(self, pkt, val):
-        return self._find_fld_pkt_val(pkt, val).i2h(pkt, val)
+        fld, val = self._find_fld_pkt_val(pkt, val)
+        return fld.i2h(pkt, val)
 
     def i2m(self, pkt, val):
-        return self._find_fld_pkt_val(pkt, val).i2m(pkt, val)
+        fld, val = self._find_fld_pkt_val(pkt, val)
+        return fld.i2m(pkt, val)
 
     def i2len(self, pkt, val):
-        return self._find_fld_pkt_val(pkt, val).i2len(pkt, val)
+        fld, val = self._find_fld_pkt_val(pkt, val)
+        return fld.i2len(pkt, val)
 
     def i2repr(self, pkt, val):
-        return self._find_fld_pkt_val(pkt, val).i2repr(pkt, val)
+        fld, val = self._find_fld_pkt_val(pkt, val)
+        return fld.i2repr(pkt, val)
 
     def register_owner(self, cls):
         for fld, _ in self.flds:

scapy/layers/l2.py

@@ -148,11 +148,6 @@ def i2m(self, pkt, x):
         return MACField.i2m(self, pkt, self.i2h(pkt, x))
 
 
-class ARPSourceMACField(SourceMACField):
-    def __init__(self, name):
-        super(ARPSourceMACField, self).__init__(name)
-
-
 # Layers
 
 ETHER_TYPES['802_AD'] = 0x88a8
@@ -326,7 +321,7 @@ class ARP(Packet):
         }),
         MultipleTypeField(
             [
-                (ARPSourceMACField("hwsrc"),
+                (SourceMACField("hwsrc"),
                  (lambda pkt: pkt.hwtype == 1 and pkt.hwlen == 6,
                   lambda pkt, val: pkt.hwtype == 1 and (
                       pkt.hwlen == 6 or (pkt.hwlen is None and
@@ -400,10 +395,16 @@ def answers(self, other):
         return self_psrc[:len(other_pdst)] == other_pdst[:len(self_psrc)]
 
     def route(self):
-        dst = self.pdst
+        fld, dst = self.getfield_and_val("pdst")
+        fld, dst = fld._find_fld_pkt_val(self, dst)
         if isinstance(dst, Gen):
             dst = next(iter(dst))
-        return conf.route.route(dst)
+        if isinstance(fld, IP6Field):
+            return conf.route6.route(dst)
+        elif isinstance(fld, IPField):
+            return conf.route.route(dst)
+        else:
+            return None
 
     def extract_padding(self, s):
         return "", s

test/fields.uts

@@ -37,7 +37,7 @@ r = m.addfield(None, b"FOO", "c0:01:be:ef:ba:be")
 r
 assert(r == b"FOO\xc0\x01\xbe\xef\xba\xbe" )
 
-= SourceMACField, ARPSourceMACField
+= SourceMACField, SourceMACField
 conf.route.add(net="1.2.3.4/32", dev=conf.iface)
 p = Ether() / ARP(pdst="1.2.3.4")
 assert p.src == p.hwsrc == p[ARP].hwsrc == get_if_hwaddr(conf.iface)
@@ -1283,6 +1283,35 @@ a = DebugPacket(addr="scapy.net", atyp=0x3)
 a = DebugPacket(raw(a))
 assert a.addr == b"scapy.net."
 
+= Test default values auto-update
+
+class SweetPacket(Packet):
+    name = 'Sweet Celestian Packet'
+    fields_desc = [
+        IntField('switch', 0),
+        MultipleTypeField([
+            (XShortField('subfield', 0xDEAD), lambda pkt: pkt.switch == 1),
+            (XIntField('subfield',  0xBEEFBEEF), lambda pkt: pkt.switch == 2)],
+            XByteField('subfield', 0x88)
+        )
+    ]
+
+o = SweetPacket()
+assert o.subfield == 0x88
+
+o = SweetPacket(switch=1)
+assert o.subfield == 0xDEAD
+
+o = SweetPacket(switch=2)
+assert o.subfield == 0xBEEFBEEF
+
+o = SweetPacket()
+assert o.subfield == 0x88
+o.switch = 1
+assert o.subfield == 0xDEAD
+o.switch = 2
+assert o.subfield == 0xBEEFBEEF
+
 ########
 ########
 + FlagsField