Merge pull request #1231 from gpotter2/lldp-length

LLDP: support complex ID types

Author: guedou

scapy/contrib/lldp.py

@@ -42,11 +42,13 @@
 
 """
 from scapy.config import conf
-from scapy.layers.dot11 import Packet
-from scapy.layers.l2 import Ether, Dot1Q, bind_layers, \
-    BitField, StrLenField, ByteEnumField, BitEnumField, \
-    BitFieldLenField, ShortField, Scapy_Exception, \
-    XStrLenField, ByteField, EnumField, ThreeBytesField
+from scapy.error import log_runtime, Scapy_Exception
+from scapy.layers.l2 import Ether, Dot1Q
+from scapy.fields import MACField, IPField, BitField, \
+         StrLenField, ByteEnumField, BitEnumField, \
+         EnumField, ThreeBytesField, BitFieldLenField, \
+         ShortField, XStrLenField
+from scapy.packet import Packet, Padding, bind_layers
 from scapy.modules.six.moves import range
 from scapy.data import ETHER_TYPES
 from scapy.compat import orb
@@ -282,6 +284,48 @@ def dissection_done(self, pkt):
 
         super(LLDPDU, self).dissection_done(pkt)
 
+    def _check(self):
+        """Overwrited by LLDPU objects"""
+        pass
+
+    def post_dissect(self, s):
+        self._check()
+        return super(LLDPDU, self).post_dissect(s)
+
+    def do_build(self):
+        self._check()
+        return super(LLDPDU, self).do_build()
+
+class _LLDPidField(StrLenField):
+    """Class that selects the type of the ID field depending
+    on the type of `subtype`"""
+    __slots__ = StrLenField.__slots__ + ["subtypes_dict"]
+
+    def __init__(self, name, default, subtypes_dict, *args, **kargs):
+        self.subtypes_dict = subtypes_dict
+        super(_LLDPidField, self).__init__(name, default, *args, **kargs)
+
+    def m2i(self, pkt, x):
+        cls = self.subtypes_dict.get(pkt.subtype, StrLenField)
+        try:
+            return (cls.m2i.__func__ if six.PY2 else cls.m2i)(self, pkt, x)
+        except:
+            log_runtime.exception("Failed to dissect " + self.name + " ! ")
+            return StrLenField.m2i(self, pkt, x)
+
+    def i2m(self, pkt, x):
+        cls = self.subtypes_dict.get(pkt.subtype, StrLenField)
+        try:
+            return (cls.i2m.__func__ if six.PY2 else cls.i2m)(self, pkt, x)
+        except:
+            log_runtime.exception("Failed to build " + self.name + " ! ")
+            return StrLenField.i2m(self, pkt, x)
+
+def _ldp_id_adjustlen(pkt, x):
+    """Return the length of the `id` field,
+    according to its real encoded type"""
+    f, v = pkt.getfield_and_val('id')
+    return len(_LLDPidField.i2m(f, pkt, v)) + 1
 
 class LLDPDUChassisID(LLDPDU):
     """
@@ -299,6 +343,11 @@ class LLDPDUChassisID(LLDPDU):
         range(0x08, 0xff): 'reserved'
     }
 
+    LLDP_CHASSIS_ID_TLV_SUBTYPES_FIELDS = {
+        0x04: MACField,
+        0x05: IPField,
+    }
+
     SUBTYPE_RESERVED = 0x00
     SUBTYPE_CHASSIS_COMPONENT = 0x01
     SUBTYPE_INTERFACE_ALIAS = 0x02
@@ -311,9 +360,9 @@ class LLDPDUChassisID(LLDPDU):
     fields_desc = [
         BitEnumField('_type', 0x01, 7, LLDPDU.TYPES),
         BitFieldLenField('_length', None, 9, length_of='id',
-                         adjust=lambda pkt, x: len(pkt.id) + 1),
+                         adjust=lambda pkt, x: _ldp_id_adjustlen(pkt, x)),
         ByteEnumField('subtype', 0x00, LLDP_CHASSIS_ID_TLV_SUBTYPES),
-        XStrLenField('id', '', length_from=lambda pkt: pkt._length - 1)
+        _LLDPidField('id', '', LLDP_CHASSIS_ID_TLV_SUBTYPES_FIELDS, length_from=lambda pkt: pkt._length - 1)
     ]
 
     def _check(self):
@@ -323,14 +372,6 @@ def _check(self):
         if conf.contribs['LLDP'].strict_mode() and not self.id:
             raise LLDPInvalidLengthField('id must be >= 1 characters long')
 
-    def post_dissect(self, s):
-        self._check()
-        return super(LLDPDUChassisID, self).post_dissect(s)
-
-    def do_build(self):
-        self._check()
-        return super(LLDPDUChassisID, self).do_build()
-
 
 class LLDPDUPortID(LLDPDU):
     """
@@ -348,6 +389,11 @@ class LLDPDUPortID(LLDPDU):
         range(0x08, 0xff): 'reserved'
     }
 
+    LLDP_PORT_ID_TLV_SUBTYPES = {
+        0x03: MACField,
+        0x04: IPField,
+    }
+
     SUBTYPE_RESERVED = 0x00
     SUBTYPE_INTERFACE_ALIAS = 0x01
     SUBTYPE_PORT_COMPONENT = 0x02
@@ -360,9 +406,9 @@ class LLDPDUPortID(LLDPDU):
     fields_desc = [
         BitEnumField('_type', 0x02, 7, LLDPDU.TYPES),
         BitFieldLenField('_length', None, 9, length_of='id',
-                         adjust=lambda pkt, x: len(pkt.id) + 1),
+                         adjust=lambda pkt, x: _ldp_id_adjustlen(pkt, x)),
         ByteEnumField('subtype', 0x00, LLDP_PORT_ID_TLV_SUBTYPES),
-        StrLenField('id', '', length_from=lambda pkt: pkt._length - 1)
+        _LLDPidField('id', '', LLDP_PORT_ID_TLV_SUBTYPES, length_from=lambda pkt: pkt._length - 1)
     ]
 
     def _check(self):
@@ -372,14 +418,6 @@ def _check(self):
         if conf.contribs['LLDP'].strict_mode() and not self.id:
             raise LLDPInvalidLengthField('id must be >= 1 characters long')
 
-    def post_dissect(self, s):
-        self._check()
-        return super(LLDPDUPortID, self).post_dissect(s)
-
-    def do_build(self):
-        self._check()
-        return super(LLDPDUPortID, self).do_build()
-
 
 class LLDPDUTimeToLive(LLDPDU):
     """
@@ -399,15 +437,6 @@ def _check(self):
             raise LLDPInvalidLengthField('length must be 2 - got '
                                          '{}'.format(self._length))
 
-    def post_dissect(self, s):
-        self._check()
-        return super(LLDPDUTimeToLive, self).post_dissect(s)
-
-    def do_build(self):
-        self._check()
-        return super(LLDPDUTimeToLive, self).do_build()
-
-
 class LLDPDUEndOfLLDPDU(LLDPDU):
     """
         ieee 802.1ab-2016 - sec. 8.5.1 / p. 26
@@ -428,14 +457,6 @@ def _check(self):
             raise LLDPInvalidLengthField('length must be 0 - got '
                                          '{}'.format(self._length))
 
-    def post_dissect(self, s):
-        self._check()
-        return super(LLDPDUEndOfLLDPDU, self).post_dissect(s)
-
-    def do_build(self):
-        self._check()
-        return super(LLDPDUEndOfLLDPDU, self).do_build()
-
 
 class LLDPDUPortDescription(LLDPDU):
     """
@@ -519,14 +540,6 @@ def _check(self):
             raise LLDPInvalidLengthField('length must be 4 - got '
                                          '{}'.format(self._length))
 
-    def post_dissect(self, s):
-        self._check()
-        return super(LLDPDUSystemCapabilities, self).post_dissect(s)
-
-    def do_build(self):
-        self._check()
-        return super(LLDPDUSystemCapabilities, self).do_build()
-
 
 class LLDPDUManagementAddress(LLDPDU):
     """
@@ -659,14 +672,6 @@ def _check(self):
                     'management address must be  1..31 characters long - '
                     'got string of size {}'.format(management_address_len))
 
-    def post_dissect(self, s):
-        self._check()
-        return super(LLDPDUManagementAddress, self).post_dissect(s)
-
-    def do_build(self):
-        self._check()
-        return super(LLDPDUManagementAddress, self).do_build()
-
 
 class ThreeBytesEnumField(EnumField, ThreeBytesField):
 

scapy/contrib/lldp.uts

@@ -31,23 +31,23 @@ frm = Ether(frm)
 conf.contribs['LLDP'].strict_mode_disable()
 frm = Ether(src='01:01:01:01:01:01', dst=LLDP_NEAREST_BRIDGE_MAC) / \
       LLDPDUPortID(subtype=LLDPDUPortID.SUBTYPE_INTERFACE_NAME, id='eth0') / \
-      LLDPDUChassisID(subtype=LLDPDUChassisID.SUBTYPE_MAC_ADDRESS, id=b'\x06\x05\x04\x03\x02\x01') / \
+      LLDPDUChassisID(subtype=LLDPDUChassisID.SUBTYPE_MAC_ADDRESS, id='06:05:04:03:02:01') / \
       LLDPDUTimeToLive() / \
       LLDPDUEndOfLLDPDU()
 assert(len(raw(frm)) == 60)
 assert(len(raw(Ether(raw(frm))[Padding])) == 24)
 
 frm = Ether(src='01:01:01:01:01:01', dst=LLDP_NEAREST_BRIDGE_MAC) / \
       LLDPDUPortID(subtype=LLDPDUPortID.SUBTYPE_INTERFACE_NAME, id='eth012345678901234567890123') / \
-      LLDPDUChassisID(subtype=LLDPDUChassisID.SUBTYPE_MAC_ADDRESS, id=b'\x06\x05\x04\x03\x02\x01') / \
+      LLDPDUChassisID(subtype=LLDPDUChassisID.SUBTYPE_MAC_ADDRESS, id='06:05:04:03:02:01') / \
       LLDPDUTimeToLive() / \
       LLDPDUEndOfLLDPDU()
 assert (len(raw(frm)) == 60)
 assert (len(raw(Ether(raw(frm))[Padding])) == 1)
 
 frm = Ether(src='01:01:01:01:01:01', dst=LLDP_NEAREST_BRIDGE_MAC) / \
       LLDPDUPortID(subtype=LLDPDUPortID.SUBTYPE_INTERFACE_NAME, id='eth0123456789012345678901234') / \
-      LLDPDUChassisID(subtype=LLDPDUChassisID.SUBTYPE_MAC_ADDRESS, id=b'\x06\x05\x04\x03\x02\x01') / \
+      LLDPDUChassisID(subtype=LLDPDUChassisID.SUBTYPE_MAC_ADDRESS, id='06:05:04:03:02:01') / \
       LLDPDUTimeToLive() / \
       LLDPDUEndOfLLDPDU()
 assert (len(raw(frm)) == 60)
@@ -58,6 +58,13 @@ except IndexError:
       pass
 
 
+= Advanced test: check length of complex IDs
+
+pkt = Ether()/LLDPDUChassisID(id="ff:dd:ee:bb:aa:99", subtype=0x04)/LLDPDUPortID(subtype=0x03, id="aa:bb:cc:dd:ee:ff")/LLDPDUTimeToLive(ttl=120)/LLDPDUEndOfLLDPDU()
+pkt = Ether(raw(pkt))
+assert pkt[LLDPDUChassisID]._length == 7
+assert pkt[LLDPDUPortID]._length == 7
+
 + strict mode handling - build
 = basic frame structure
 
@@ -168,8 +175,8 @@ frm = Ether(frm.build())
 conf.contribs['LLDP'].strict_mode_enable()
 
 frm = Ether(src='01:01:01:01:01:01', dst=LLDP_NEAREST_BRIDGE_MAC)/ \
-      LLDPDUChassisID(subtype=LLDPDUChassisID.SUBTYPE_MAC_ADDRESS, id=b'\x06\x05\x04\x03\x02\x01') / \
-      LLDPDUPortID(subtype=LLDPDUPortID.SUBTYPE_MAC_ADDRESS, id=b'\x01\x02\x03\x04\x05\x06')/\
+      LLDPDUChassisID(subtype=LLDPDUChassisID.SUBTYPE_MAC_ADDRESS, id='06:05:04:03:02:01') / \
+      LLDPDUPortID(subtype=LLDPDUPortID.SUBTYPE_MAC_ADDRESS, id='01:02:03:04:05:06')/\
       LLDPDUTimeToLive()/\
       LLDPDUSystemName(system_name='things will')/\
       LLDPDUSystemCapabilities(telephone_available=1,
@@ -188,8 +195,8 @@ frm = Ether(src='01:01:01:01:01:01', dst=LLDP_NEAREST_BRIDGE_MAC)/ \
 
 frm = Ether(frm.build())
 
-assert str2mac(frm[LLDPDUChassisID].id) == '06:05:04:03:02:01'
-assert str2mac(frm[LLDPDUPortID].id) == '01:02:03:04:05:06'
+assert frm[LLDPDUChassisID].id == '06:05:04:03:02:01'
+assert frm[LLDPDUPortID].id == '01:02:03:04:05:06'
 sys_capabilities = frm[LLDPDUSystemCapabilities]
 assert sys_capabilities.reserved_5_available == 0
 assert sys_capabilities.reserved_4_available == 0

scapy/utils.py

@@ -368,7 +368,7 @@ def fletcher16_checkbytes(binbuf, offset):
 
 
 def mac2str(mac):
-    return b"".join(chb(int(x, 16)) for x in mac.split(':'))
+    return b"".join(chb(int(x, 16)) for x in plain_str(mac).split(':'))
 
 def str2mac(s):
     if isinstance(s, str):