Add 802.11 Microsoft WME element support

scapy/layers/dot11.py

@@ -1476,14 +1476,15 @@ class Dot11EltMicrosoftWPA(Dot11EltVendorSpecific):
     @classmethod
     def dispatch_hook(cls, _pkt=None, *args, **kargs):
         if _pkt:
+            if len(_pkt) < 6:
+                return Dot11EltVendorSpecific
             type_ = orb(_pkt[5])
             if type_ == 0x01:
                 # MS WPA IE
                 return Dot11EltMicrosoftWPA
             elif type_ == 0x02:
-                # MS WME IE TODO
-                # return Dot11EltMicrosoftWME
-                pass
+                # MS WME IE
+                return Dot11EltMicrosoftWME
             elif type_ == 0x04:
                 # MS WPS IE TODO
                 # return Dot11EltWPS
@@ -1492,6 +1493,95 @@ def dispatch_hook(cls, _pkt=None, *args, **kargs):
         return cls
 
 
+_dot11_wme_subtypes = {
+    0: "Information",
+    1: "Parameter",
+}
+
+
+_dot11_wme_ac_aci = {
+    0: "Best Effort",
+    1: "Background",
+    2: "Video",
+    3: "Voice",
+}
+
+
+def _dot11_wme_remaining_len(pkt):
+    subtype = getattr(pkt, "subtype", None)
+    if subtype == 1 and pkt.len >= 24:
+        consumed = 24
+    elif subtype == 1 and pkt.len >= 8:
+        consumed = 8
+    elif pkt.len >= 5:
+        consumed = min(pkt.len, 7)
+    else:
+        consumed = 4
+    return max(pkt.len - consumed, 0)
+
+
+class Dot11WMEACParameter(Packet):
+    name = "802.11 WME AC Parameter"
+    fields_desc = [
+        BitField("reserved", 0, 1, tot_size=-1),
+        BitEnumField("aci", 0, 2, _dot11_wme_ac_aci),
+        BitField("acm", 0, 1),
+        BitField("aifsn", 0, 4, end_tot_size=-1),
+        BitField("ecw_max", 0, 4, tot_size=-1),
+        BitField("ecw_min", 0, 4, end_tot_size=-1),
+        LEShortField("txop_limit", 0),
+    ]
+
+    def extract_padding(self, s):
+        return b"", s
+
+
+class Dot11EltMicrosoftWME(Dot11EltVendorSpecific):
+    name = "802.11 Microsoft WMM WME"
+    match_subclass = True
+    ID = 221
+    oui = 0x0050f2
+    fields_desc = Dot11EltVendorSpecific.fields_desc[:3] + [
+        XByteField("type", 0x02),
+        ConditionalField(
+            ByteEnumField("subtype", 0, _dot11_wme_subtypes),
+            lambda pkt: pkt.len >= 5
+        ),
+        ConditionalField(
+            ByteField("version", 1),
+            lambda pkt: pkt.len >= 6
+        ),
+        ConditionalField(
+            ByteField("qos_info", 0),
+            lambda pkt: pkt.len >= 7
+        ),
+        ConditionalField(
+            ByteField("reserved", 0),
+            lambda pkt: (
+                getattr(pkt, "subtype", None) == 1 and
+                pkt.len >= 8
+            )
+        ),
+        ConditionalField(
+            PacketListField(
+                "ac_params",
+                [],
+                Dot11WMEACParameter,
+                count_from=lambda pkt: 4
+            ),
+            lambda pkt: (
+                getattr(pkt, "subtype", None) == 1 and
+                pkt.len >= 24
+            )
+        ),
+        StrLenField(
+            "info",
+            b"",
+            length_from=_dot11_wme_remaining_len
+        )
+    ]
+
+
 # 802.11-2016 9.4.2.19
 
 class Dot11EltCSA(Dot11Elt):

test/scapy/layers/dot11.uts

@@ -282,6 +282,47 @@ assert ms_wpa_ie[Dot11EltMicrosoftWPA].nb_akm_suites == 0x01
 assert ms_wpa_ie[Dot11EltMicrosoftWPA].akm_suites[0].suite == 0x01
 assert Dot11Elt in ms_wpa_ie
 
+= Dot11EltMicrosoftWME
+ms_wme_info_ie = Dot11Elt(b'\xdd\x07\x00P\xf2\x02\x00\x01\x80\x00\x04test')
+assert Dot11EltMicrosoftWME in ms_wme_info_ie
+assert ms_wme_info_ie[Dot11EltMicrosoftWME].type == 0x02
+assert ms_wme_info_ie[Dot11EltMicrosoftWME].subtype == 0x00
+assert ms_wme_info_ie[Dot11EltMicrosoftWME].version == 0x01
+assert ms_wme_info_ie[Dot11EltMicrosoftWME].qos_info == 0x80
+assert ms_wme_info_ie[Dot11EltMicrosoftWME].getfieldval("info") == b""
+assert Dot11Elt in ms_wme_info_ie
+assert raw(ms_wme_info_ie) == b'\xdd\x07\x00P\xf2\x02\x00\x01\x80\x00\x04test'
+
+ms_wme_param_ie = Dot11Elt(
+    b'\xdd\x18\x00P\xf2\x02\x01\x01\x80\x00'
+    b'\x03\xa4\x00\x00\x27\xa4\x00\x00\x42\x43\x5e\x00\x62\x32\x2f\x00'
+    b'\x00\x04test'
+)
+assert Dot11EltMicrosoftWME in ms_wme_param_ie
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].subtype == 0x01
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].version == 0x01
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].qos_info == 0x80
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].reserved == 0
+assert len(ms_wme_param_ie[Dot11EltMicrosoftWME].ac_params) == 4
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].ac_params[0].aci == 0
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].ac_params[0].aifsn == 3
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].ac_params[0].ecw_min == 4
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].ac_params[0].ecw_max == 10
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].ac_params[1].aci == 1
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].ac_params[2].aci == 2
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].ac_params[3].aci == 3
+assert ms_wme_param_ie[Dot11EltMicrosoftWME].getfieldval("info") == b""
+assert Dot11Elt in ms_wme_param_ie
+assert raw(ms_wme_param_ie) == (
+    b'\xdd\x18\x00P\xf2\x02\x01\x01\x80\x00'
+    b'\x03\xa4\x00\x00\x27\xa4\x00\x00\x42\x43\x5e\x00\x62\x32\x2f\x00'
+    b'\x00\x04test'
+)
+
+short_ms_vendor_ie = Dot11Elt(b'\xdd\x03\x00P\xf2')
+assert short_ms_vendor_ie.__class__ == Dot11EltVendorSpecific
+assert raw(short_ms_vendor_ie) == b'\xdd\x03\x00P\xf2'
+
 = Dot11EltVendorSpecific
 assert bytes(Dot11EltVendorSpecific()) == b'\xdd\x03\x00\x00\x00'
 vendor_specific_ie = Dot11EltVendorSpecific(b'\xdd\t\x00\x03\x7f\x01\x01\x00\x00\xff\x7f')