Introduce 802.11 dissectors with wired-in "FCS present" indications.

For a number of protocols that encapsulate 802.11 frames inside packets,
whether the frame includes an FCS or not is specified by the protocol,
not by whether the link-layer frame carrying the packets *itself*
includes an FCS.  As we've done with Ethernet, add "_withfcs" and
"_withoutfcs" dissectors, which *don't* check the pseudo-header FCS
length indication, and call those, rather than dissectors that check the
pseudo-header length indication, from the dissectors for those protocols.

Change-Id: Ib8c8ecdd872e1782fdfc66e7573415d91911a62e
Reviewed-on: https://code.wireshark.org/review/1866
Reviewed-by: Guy Harris <guy@alum.mit.edu>

8 files changed, 56 insertions, 24 deletions

diff --git a/epan/dissectors/packet-aruba-erm.c b/epan/dissectors/packet-aruba-erm.c
index 6325b88d14..3cc9be1513 100644
--- a/epan/dissectors/packet-aruba-erm.c
+++ b/epan/dissectors/packet-aruba-erm.c
@@ -282,7 +282,7 @@ proto_reg_handoff_aruba_erm(void)
     static gboolean initialized = FALSE;
 
     if (!initialized) {
-        ieee80211_handle = find_dissector("wlan");
+        ieee80211_handle = find_dissector("wlan_withoutfcs");
         ppi_handle = find_dissector("ppi");
         peek_handle = find_dissector("peekremote");
         data_handle = find_dissector("data");
diff --git a/epan/dissectors/packet-capwap.c b/epan/dissectors/packet-capwap.c
index 38aea4db24..29e8bc5108 100644
--- a/epan/dissectors/packet-capwap.c
+++ b/epan/dissectors/packet-capwap.c
@@ -2607,7 +2607,7 @@ proto_reg_handoff_capwap(void)
         capwap_data_handle    = create_dissector_handle(dissect_capwap_data, proto_capwap);
         dtls_handle           = find_dissector("dtls");
         ieee8023_handle       = find_dissector("eth_withoutfcs");
-        ieee80211_handle      = find_dissector("wlan");
+        ieee80211_handle      = find_dissector("wlan_withoutfcs");
         ieee80211_bsfc_handle = find_dissector("wlan_bsfc");
         data_handle           = find_dissector("data");
 
diff --git a/epan/dissectors/packet-cisco-wids.c b/epan/dissectors/packet-cisco-wids.c
index 66f882b001..fe98b2b074 100644
--- a/epan/dissectors/packet-cisco-wids.c
+++ b/epan/dissectors/packet-cisco-wids.c
@@ -196,7 +196,7 @@ proto_reg_handoff_cwids(void)
 	if (!initialized) {
 		cwids_handle = create_dissector_handle(dissect_cwids, proto_cwids);
 		dissector_add_handle("udp.port", cwids_handle);
-		ieee80211_handle = find_dissector("wlan");
+		ieee80211_handle = find_dissector("wlan_withoutfcs");
 		initialized = TRUE;
 	} else {
 		if (saved_udp_port != 0) {
diff --git a/epan/dissectors/packet-ieee80211.c b/epan/dissectors/packet-ieee80211.c
index 3904880c27..7f78a5dbeb 100644
--- a/epan/dissectors/packet-ieee80211.c
+++ b/epan/dissectors/packet-ieee80211.c
@@ -17586,7 +17586,8 @@ dissect_ieee80211_common (tvbuff_t *tvb, packet_info *pinfo,
 }
 
 /*
- * Dissect 802.11 with a variable-length link-layer header.
+ * Dissect 802.11 with a variable-length link-layer header and with the FCS
+ * presence or absence indicated by the pseudo-header.
  */
 static void
 dissect_ieee80211 (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
@@ -17596,6 +17597,26 @@ dissect_ieee80211 (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 }
 
 /*
+ * Dissect 802.11 with a variable-length link-layer header and with an
+ * FCS.
+ */
+static void
+dissect_ieee80211_withfcs (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+  dissect_ieee80211_common (tvb, pinfo, tree, FALSE, 4, FALSE, FALSE, FALSE, FALSE);
+}
+
+/*
+ * Dissect 802.11 with a variable-length link-layer header and without an
+ * FCS.
+ */
+static void
+dissect_ieee80211_withoutfcs (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+  dissect_ieee80211_common (tvb, pinfo, tree, FALSE, 0, FALSE, FALSE, FALSE, FALSE);
+}
+
+/*
  * Dissect 802.11 with a variable-length link-layer header.
  */
 static void
@@ -17606,19 +17627,29 @@ dissect_ieee80211_centrino(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 }
 
 /*
- * Dissect 802.11 with a variable-length link-layer header and data padding.
+ * Dissect 802.11 with a variable-length link-layer header and data padding
+ * and with an FCS.
  */
 static void
-dissect_ieee80211_datapad (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+dissect_ieee80211_datapad_withfcs (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 {
-  dissect_ieee80211_common (tvb, pinfo, tree, FALSE,
-                            pinfo->pseudo_header->ieee_802_11.fcs_len, FALSE, TRUE, FALSE, FALSE);
+  dissect_ieee80211_common (tvb, pinfo, tree, FALSE, 4, FALSE, TRUE, FALSE, FALSE);
+}
+
+/*
+ * Dissect 802.11 with a variable-length link-layer header and data padding
+ * and without an FCS.
+ */
+static void
+dissect_ieee80211_datapad_withoutfcs (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+  dissect_ieee80211_common (tvb, pinfo, tree, FALSE, 0, FALSE, TRUE, FALSE, FALSE);
 }
 
 /*
  * Dissect 802.11 with a variable-length link-layer header and a byte-swapped
- * control field (some hardware sends out LWAPP-encapsulated 802.11
- * packets with the control field byte swapped).
+ * control field and with no FCS (some hardware sends out LWAPP-encapsulated
+ * 802.11 packets with the control field byte swapped).
  */
 static void
 dissect_ieee80211_bsfc (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
@@ -17628,7 +17659,7 @@ dissect_ieee80211_bsfc (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 
 /*
  * Dissect 802.11 with a fixed-length link-layer header (padded to the
- * maximum length).
+ * maximum length) and no FCS.
  */
 static void
 dissect_ieee80211_fixed (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
@@ -25873,11 +25904,14 @@ proto_register_ieee80211 (void)
   expert_ieee80211 = expert_register_protocol(proto_wlan);
   expert_register_field_array(expert_ieee80211, ei, array_length(ei));
 
-  register_dissector("wlan",         dissect_ieee80211,         proto_wlan);
-  register_dissector("wlan_fixed",   dissect_ieee80211_fixed,   proto_wlan);
-  register_dissector("wlan_bsfc",    dissect_ieee80211_bsfc,    proto_wlan);
-  register_dissector("wlan_datapad", dissect_ieee80211_datapad, proto_wlan);
-  register_dissector("wlan_ht",      dissect_ieee80211_ht,      proto_wlan);
+  register_dissector("wlan",                    dissect_ieee80211,            proto_wlan);
+  register_dissector("wlan_withfcs",            dissect_ieee80211_withfcs,    proto_wlan);
+  register_dissector("wlan_withoutfcs",         dissect_ieee80211_withoutfcs, proto_wlan);
+  register_dissector("wlan_fixed",              dissect_ieee80211_fixed,      proto_wlan);
+  register_dissector("wlan_bsfc",               dissect_ieee80211_bsfc,       proto_wlan);
+  register_dissector("wlan_datapad_withfcs",    dissect_ieee80211_datapad_withfcs,    proto_wlan);
+  register_dissector("wlan_datapad_withoutfcs", dissect_ieee80211_datapad_withoutfcs, proto_wlan);
+  register_dissector("wlan_ht",                 dissect_ieee80211_ht,         proto_wlan);
 
   register_init_routine(wlan_defragment_init);
   register_init_routine(wlan_retransmit_init);
diff --git a/epan/dissectors/packet-lwapp.c b/epan/dissectors/packet-lwapp.c
index 50ca5e4a02..5ff54d1355 100644
--- a/epan/dissectors/packet-lwapp.c
+++ b/epan/dissectors/packet-lwapp.c
@@ -1,7 +1,7 @@
 /* packet-lwapp.c
  *
  * Routines for LWAPP encapsulated packet disassembly
- * draft-ohara-capwap-lwapp-N (the current draft is 0)
+ * RFC 5412
  *
  * Copyright (c) 2003 by David Frascone <dave@frascone.com>
  *
@@ -547,7 +547,7 @@ proto_reg_handoff_lwapp(void)
      * Get handles for the Ethernet and wireless dissectors.
      */
     eth_withoutfcs_handle = find_dissector("eth_withoutfcs");
-    wlan_handle = find_dissector("wlan");
+    wlan_handle = find_dissector("wlan_withoutfcs");
     wlan_bsfc_handle = find_dissector("wlan_bsfc");
     data_handle = find_dissector("data");
 
diff --git a/epan/dissectors/packet-peekremote.c b/epan/dissectors/packet-peekremote.c
index 42be430875..be4e32e913 100644
--- a/epan/dissectors/packet-peekremote.c
+++ b/epan/dissectors/packet-peekremote.c
@@ -450,7 +450,6 @@ dissect_peekremote_new(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void
 
   proto_item_set_end(ti, tvb, offset);
   next_tvb = tvb_new_subset_remaining(tvb, offset);
-  pinfo->pseudo_header->ieee_802_11.fcs_len = 4;
   call_dissector(ieee80211_handle, next_tvb, pinfo, tree);
   return TRUE;
 }
@@ -492,7 +491,6 @@ dissect_peekremote_legacy(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, v
   }
   proto_item_set_end(ti, tvb, 20);
   next_tvb = tvb_new_subset_remaining(tvb, 20);
-  pinfo->pseudo_header->ieee_802_11.fcs_len = 4;
   return 20 + call_dissector(ieee80211_handle, next_tvb, pinfo, tree);
 }
 
@@ -575,7 +573,7 @@ proto_reg_handoff_peekremote(void)
 {
   dissector_handle_t peekremote_handle;
 
-  ieee80211_handle = find_dissector("wlan_datapad");
+  ieee80211_handle = find_dissector("wlan_datapad_withfcs");
 
   peekremote_handle = new_create_dissector_handle(dissect_peekremote_legacy, proto_peekremote);
   dissector_add_uint("udp.port", 5000, peekremote_handle);
diff --git a/epan/dissectors/packet-sflow.c b/epan/dissectors/packet-sflow.c
index 14a6824ba4..53686c0a96 100644
--- a/epan/dissectors/packet-sflow.c
+++ b/epan/dissectors/packet-sflow.c
@@ -3661,7 +3661,7 @@ proto_reg_handoff_sflow_245(void) {
         /* wireshark does not have POS dissector yet */
         pos_handle = data_handle;
 #endif
-        ieee80211_mac_handle = find_dissector("wlan");
+        ieee80211_mac_handle = find_dissector("wlan_withoutfcs");
 #if 0
         ieee80211_ampdu_handle = find_dissector("ampdu");
         ieee80211_amsdu_subframe_handle = find_dissector("wlan_aggregate");
diff --git a/epan/dissectors/packet-wassp.c b/epan/dissectors/packet-wassp.c
index e6bb373e0f..a822c5320d 100644
--- a/epan/dissectors/packet-wassp.c
+++ b/epan/dissectors/packet-wassp.c
@@ -24,7 +24,7 @@
  */
 
 /*
-  http://ietfreport.isoc.org/all-ids/draft-singh-capwap-ctp-02.txt
+  https://tools.ietf.org/html/draft-singh-capwap-ctp-02
   looks very similar (but not always identical).
 
   AC: Access Controller
@@ -2113,6 +2113,6 @@ proto_reg_handoff_wassp(void)
 #endif
 
 	snmp_handle = find_dissector("snmp");
-	ieee80211_handle = find_dissector("wlan");
+	ieee80211_handle = find_dissector("wlan_withoutfcs");
 }