Copy over r45545 from trunk:

  ------------------------------------------------------------------------
  r45545 | guy | 2012-10-14 15:38:58 -0700 (Sun, 14 Oct 2012) | 28 lines

  According to

	http://home.martin.cc/linux/prism

  there's a set of DID type values different from the ones we were using,
  and there are captures out there that use values from both sets. 
  Support both sets.

  That page also says that a "status" value of 0 means "supplied"; treat
  zero as meaning "supplied", and, if it's not zero for a field, don't
  include it.

  The "Mac Time" is, according to that page, the lower 32 bits of the MAC
  timestamp; report it as such.

  Fix some field names that were copied-and-pasted but not changed.

  The RSSI and signal quality values are numbers, so show them in decimal.

  The "signal" and "noise" values appear to be signed numbers, so make
  them signed rather than unsigned and show them in decimal.

  Show the data rate in the same style as it's shown in the radiotap
  dissector.

  Show the frame length in decimal; we probably have relatively few users
  with 16 fingers.

svn path=/trunk-1.8/; revision=45546

1 files changed, 174 insertions, 103 deletions

diff --git a/epan/dissectors/packet-ieee80211-prism.c b/epan/dissectors/packet-ieee80211-prism.c
index fbc1168445..0cb5c17a9f 100644
--- a/epan/dissectors/packet-ieee80211-prism.c
+++ b/epan/dissectors/packet-ieee80211-prism.c
@@ -117,39 +117,87 @@ static gint ett_prism_did = -1;
  *
  * XXX - what about other drivers that supply Prism headers, such as
  * old versions of the MadWifi driver?
+ *
+ * I'm not sure where these DID values come from, but they work with
+ * at least one capture file.  However, in
+ *
+ *    http://ask.wireshark.org/questions/14963/how-to-get-the-field-did-unknown-4041-into-the-column
+ *
+ * somebody reports a capture where *different* DID values, corresponding
+ * to
+ *
+ *    http://home.martin.cc/linux/prism
+ *
+ * are used (and that's not a byte-order issue, as those values are *not*
+ * just byte-swapped versions of the other values).
  */
 
 #define PRISM_HEADER_LENGTH     144             /* Default Prism Header Length */
-#define PRISM_DID_HOSTTIME      0x00010044      /* Host time element */
-#define PRISM_DID_MACTIME       0x00020044      /* Mac time element */
-#define PRISM_DID_CHANNEL       0x00030044      /* Channel element */
-#define PRISM_DID_RSSI          0x00040044      /* RSSI element */
-#define PRISM_DID_SQ            0x00050044      /* SQ element */
-#define PRISM_DID_SIGNAL        0x00060044      /* Signal element */
-#define PRISM_DID_NOISE         0x00070044      /* Noise element */
-#define PRISM_DID_RATE          0x00080044      /* Rate element */
-#define PRISM_DID_ISTX          0x00090044      /* Is Tx frame */
-#define PRISM_DID_FRMLEN        0x000A0044      /* Frame length */
+
+/*
+ * From the page cited above.  What's this?
+ */
+#define PRISM_MSGCODE            0x00000041      /* Monitor Frame */
+
+/*
+ * DID codes - PRISM_DID1_xxx are the non-home.martin.cc values, and
+ * PRISM_DID2_xxx are the home.martin.cc values.
+ */
+#define PRISM_DID1_HOSTTIME      0x00010044      /* Host time element */
+#define PRISM_DID2_HOSTTIME      0x00001041
+#define PRISM_DID1_MACTIME       0x00020044      /* Mac time element */
+#define PRISM_DID2_MACTIME       0x00002041
+#define PRISM_DID1_CHANNEL       0x00030044      /* Channel element */
+#define PRISM_DID2_CHANNEL       0x00003041 
+#define PRISM_DID1_RSSI          0x00040044      /* RSSI element */
+#define PRISM_DID2_RSSI          0x00004041
+#define PRISM_DID1_SQ            0x00050044      /* SQ element */
+#define PRISM_DID2_SQ            0x00005041
+#define PRISM_DID1_SIGNAL        0x00060044      /* Signal element */
+#define PRISM_DID2_SIGNAL        0x00006041
+#define PRISM_DID1_NOISE         0x00070044      /* Noise element */
+#define PRISM_DID2_NOISE         0x00007041
+#define PRISM_DID1_RATE          0x00080044      /* Rate element */
+#define PRISM_DID2_RATE          0x00008041
+#define PRISM_DID1_ISTX          0x00090044      /* Is Tx frame */
+#define PRISM_DID2_ISTX          0x00009041
+#define PRISM_DID1_FRMLEN        0x000A0044      /* Frame length */
+#define PRISM_DID2_FRMLEN        0x0000A041
 
 static const value_string prism_did_vals[] =
 {
-  { PRISM_DID_HOSTTIME,   "Host Time" },
-  { PRISM_DID_MACTIME,    "Mac Time" },
-  { PRISM_DID_CHANNEL,    "Channel" },
-  { PRISM_DID_RSSI,       "RSSI" },
-  { PRISM_DID_SQ,         "SQ" },
-  { PRISM_DID_SIGNAL,     "Signal" },
-  { PRISM_DID_NOISE,      "Noise" },
-  { PRISM_DID_RATE,       "Rate" },
-  { PRISM_DID_ISTX,       "Is Tx" },
-  { PRISM_DID_FRMLEN,     "Frame Length" },
+  { PRISM_DID1_HOSTTIME,   "Host Time" },
+  { PRISM_DID2_HOSTTIME,   "Host Time" },
+  { PRISM_DID1_MACTIME,    "Mac Time" },
+  { PRISM_DID2_MACTIME,    "Mac Time" },
+  { PRISM_DID1_CHANNEL,    "Channel" },
+  { PRISM_DID2_CHANNEL,    "Channel" },
+  { PRISM_DID1_RSSI,       "RSSI" },
+  { PRISM_DID2_RSSI,       "RSSI" },
+  { PRISM_DID1_SQ,         "SQ" },
+  { PRISM_DID2_SQ,         "SQ" },
+  { PRISM_DID1_SIGNAL,     "Signal" },
+  { PRISM_DID2_SIGNAL,     "Signal" },
+  { PRISM_DID1_NOISE,      "Noise" },
+  { PRISM_DID2_NOISE,      "Noise" },
+  { PRISM_DID1_RATE,       "Rate" },
+  { PRISM_DID2_RATE,       "Rate" },
+  { PRISM_DID1_ISTX,       "Is Tx" },
+  { PRISM_DID2_ISTX,       "Is Tx" },
+  { PRISM_DID1_FRMLEN,     "Frame Length" },
+  { PRISM_DID2_FRMLEN,     "Frame Length" },
   { 0, NULL}
 };
 
+/*
+ * The header file mentioned above says 0 means "supplied" and 1 means
+ * "not supplied".  I haven't seen a capture file with anything other
+ * than 0 there.
+ */
 static const value_string prism_status_vals[] =
 {
-  { 0,   "Not Supplied" },
-  { 1,   "Supplied" },
+  { 0,   "Supplied" },
+  { 1,   "Not Supplied" },
   { 0, NULL}
 };
 
@@ -215,6 +263,7 @@ dissect_prism(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
     tvbuff_t *next_tvb;
     int offset;
     guint32 msgcode, msglen, did;
+    guint16 status;
     guint8 *devname;
 
     offset = 0;
@@ -275,6 +324,7 @@ dissect_prism(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 
 
         /* Status */
+        status = tvb_get_letohs(tvb, offset);
         if(tree) {
             proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_status, tvb, offset, 2, ENC_LITTLE_ENDIAN);
         }
@@ -286,77 +336,98 @@ dissect_prism(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
         }
         offset += 2;
 
-        /* Data... */
-        switch(did){
-          case PRISM_DID_HOSTTIME:
-            if(tree){
-                proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_hosttime, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                proto_item_append_text(ti_did, " %d", tvb_get_letohl(tvb, offset) );
-            }
-          break;
-          case PRISM_DID_MACTIME:
-            if(tree){
-                proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_mactime, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                proto_item_append_text(ti_did, " %d", tvb_get_letohl(tvb, offset) );
-            }
-          break;
-          case PRISM_DID_CHANNEL:
-            if(tree){
-                proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_channel, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                proto_item_append_text(ti_did, " %d", tvb_get_letohl(tvb, offset) );
-            }
-            col_add_fstr(pinfo->cinfo, COL_FREQ_CHAN, "%u", tvb_get_letohl(tvb, offset));
-          break;
-          case PRISM_DID_RSSI:
-            if(tree){
-                proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_rssi, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
-            }
-            col_add_fstr(pinfo->cinfo, COL_RSSI, "%d", tvb_get_letohl(tvb, offset));
-          break;
-          case PRISM_DID_SQ:
-            if(tree){
-                  proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_sq, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                  proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
-            }
-          break;
-          case PRISM_DID_SIGNAL:
-            if(tree){
-                proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_signal, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
-            }
-          break;
-          case PRISM_DID_NOISE:
-            if(tree){
-                proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_noise, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
-            }
-          break;
-          case PRISM_DID_RATE:
-            if(tree){
-                proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_rate, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                proto_item_append_text(ti_did, " %s Mb/s", prism_rate_return(tvb_get_letohl(tvb, offset)) );
-            }
-            col_add_fstr(pinfo->cinfo, COL_TX_RATE, "%s", prism_rate_return(tvb_get_letohl(tvb, offset)) );
-
-          break;
-          case PRISM_DID_ISTX:
-            if(tree){
-                proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_istx, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
-            }
-          break;
-          case PRISM_DID_FRMLEN:
-            if(tree){
-                proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_frmlen, tvb, offset, 4, ENC_LITTLE_ENDIAN);
-                proto_item_append_text(ti_did, " %d", tvb_get_letohl(tvb, offset) );
-            }
-          break;
-          default:
-            if(tree){
-                  proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_unknown, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+        /* Data, if present... */
+        if (status == 0) {
+            switch(did){
+              case PRISM_DID1_HOSTTIME:
+              case PRISM_DID2_HOSTTIME:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_hosttime, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                    proto_item_append_text(ti_did, " %d", tvb_get_letohl(tvb, offset) );
+                }
+              break;
+
+              case PRISM_DID1_MACTIME:
+              case PRISM_DID2_MACTIME:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_mactime, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                    proto_item_append_text(ti_did, " %d", tvb_get_letohl(tvb, offset) );
+                }
+              break;
+
+              case PRISM_DID1_CHANNEL:
+              case PRISM_DID2_CHANNEL:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_channel, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                    proto_item_append_text(ti_did, " %d", tvb_get_letohl(tvb, offset) );
+                }
+                col_add_fstr(pinfo->cinfo, COL_FREQ_CHAN, "%u", tvb_get_letohl(tvb, offset));
+              break;
+
+              case PRISM_DID1_RSSI:
+              case PRISM_DID2_RSSI:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_rssi, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                    proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
+                }
+                col_add_fstr(pinfo->cinfo, COL_RSSI, "%d", tvb_get_letohl(tvb, offset));
+              break;
+
+              case PRISM_DID1_SQ:
+              case PRISM_DID2_SQ:
+                 if(tree){
+                      proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_sq, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                      proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
+                }
+              break;
+
+              case PRISM_DID1_SIGNAL:
+              case PRISM_DID2_SIGNAL:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_signal, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                    proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
+                }
+              break;
+
+              case PRISM_DID1_NOISE:
+              case PRISM_DID2_NOISE:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_noise, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                    proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
+                }
+              break;
+
+              case PRISM_DID1_RATE:
+              case PRISM_DID2_RATE:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_rate, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                    proto_item_append_text(ti_did, " %s Mb/s", prism_rate_return(tvb_get_letohl(tvb, offset)) );
+                }
+                col_add_fstr(pinfo->cinfo, COL_TX_RATE, "%s", prism_rate_return(tvb_get_letohl(tvb, offset)) );
+              break;
+
+              case PRISM_DID1_ISTX:
+              case PRISM_DID2_ISTX:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_istx, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                    proto_item_append_text(ti_did, " 0x%x", tvb_get_letohl(tvb, offset) );
+                }
+              break;
+
+              case PRISM_DID1_FRMLEN:
+              case PRISM_DID2_FRMLEN:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_frmlen, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                    proto_item_append_text(ti_did, " %d", tvb_get_letohl(tvb, offset) );
+                }
+              break;
+
+              default:
+                if(tree){
+                    proto_tree_add_item(prism_did_tree, hf_ieee80211_prism_did_unknown, tvb, offset, 4, ENC_LITTLE_ENDIAN);
+                }
+              break;
             }
-          break;
         }
         offset += 4;
     }
@@ -402,39 +473,39 @@ static hf_register_info hf_prism[] = {
       "In jiffies - for our system this is in 10ms units", HFILL }},
 
     { &hf_ieee80211_prism_did_mactime,
-     {"Mac Time", "prism.did.hosttime", FT_UINT32, BASE_DEC, NULL, 0x0,
-      "In micro-seconds", HFILL }},
+     {"MAC timestamp (lower 32 bits)", "prism.did.mactime", FT_UINT32, BASE_DEC, NULL, 0x0,
+      "Lower 32 bits of value in microseconds of the MAC's Time Synchronization Function timer when the first bit of the MPDU arrived at the MAC.", HFILL }},
 
     { &hf_ieee80211_prism_did_channel,
-     {"Channel", "prism.did.hosttime", FT_UINT32, BASE_DEC, NULL, 0x0,
+     {"Channel", "prism.did.channel", FT_UINT32, BASE_DEC, NULL, 0x0,
       NULL, HFILL }},
 
     { &hf_ieee80211_prism_did_rssi,
-     {"RSSI", "prism.did.rssi", FT_UINT32, BASE_HEX, NULL, 0x0,
+     {"RSSI", "prism.did.rssi", FT_INT32, BASE_DEC, NULL, 0x0,
       NULL, HFILL }},
 
     { &hf_ieee80211_prism_did_sq,
-     {"SQ", "prism.did.sq", FT_UINT32, BASE_HEX, NULL, 0x0,
+     {"Signal Quality", "prism.did.sq", FT_UINT32, BASE_DEC, NULL, 0x0,
       NULL, HFILL }},
 
     { &hf_ieee80211_prism_did_signal,
-     {"Signal", "prism.did.signal", FT_UINT32, BASE_HEX, NULL, 0x0,
+     {"Signal", "prism.did.signal", FT_INT32, BASE_DEC, NULL, 0x0,
       NULL, HFILL }},
 
     { &hf_ieee80211_prism_did_noise,
-     {"Noise", "prism.did.noise", FT_UINT32, BASE_HEX, NULL, 0x0,
+     {"Noise", "prism.did.noise", FT_INT32, BASE_DEC, NULL, 0x0,
       NULL, HFILL }},
 
     { &hf_ieee80211_prism_did_rate,
-     {"Rate (In Mb/s)", "prism.did.rate", FT_UINT32, BASE_CUSTOM, prism_rate_base_custom, 0x0,
-      "In Mb/s", HFILL }},
+     {"Data rate (Mb/s)", "prism.did.rate", FT_UINT32, BASE_CUSTOM, prism_rate_base_custom, 0x0,
+      "Speed this frame was sent/received at", HFILL }},
 
     { &hf_ieee80211_prism_did_istx,
      {"IsTX", "prism.did.istx", FT_UINT32, BASE_HEX, VALS(prism_istx_vals), 0x0,
-      "Type of packet (RX or TX ?)", HFILL }},
+      "Type of packet (RX or TX?)", HFILL }},
 
     { &hf_ieee80211_prism_did_frmlen,
-     {"Frame Length", "prism.did.frmlen", FT_UINT32, BASE_HEX_DEC, NULL, 0x0,
+     {"Frame Length", "prism.did.frmlen", FT_UINT32, BASE_DEC, NULL, 0x0,
       "Length of the following frame in bytes", HFILL }},
 
     { &hf_ieee80211_prism_did_unknown,