Add support for extended sequence numbers as specified in Annex A of Q.703.

svn path=/trunk/; revision=13042

1 files changed, 132 insertions, 60 deletions

diff --git a/epan/dissectors/packet-mtp2.c b/epan/dissectors/packet-mtp2.c
index 9dfc559b6c..e643f60dfa 100644
--- a/epan/dissectors/packet-mtp2.c
+++ b/epan/dissectors/packet-mtp2.c
@@ -1,9 +1,9 @@
 /* packet-mtp2.c
  * Routines for MTP2 dissection
  * It is hopefully (needs testing) compliant to
- * ITU-T Q.703
+ * ITU-T Q.703 and Q.703 Annex A.
  *
- * Copyright 2001, Michael Tuexen <tuexen [AT] fh-muenster.de>
+ * Copyright 2001, 2004 Michael Tuexen <tuexen [AT] fh-muenster.de>
  *
  * $Id$
  *
@@ -34,53 +34,91 @@
 
 #include <glib.h>
 #include <epan/packet.h>
+#include "epan/prefs.h"
 
 #define LITTLE_ENDIAN_BYTE_ORDER TRUE
 
 /* Initialize the protocol and registered fields */
-static int proto_mtp2      = -1;
-static int hf_mtp2_bsn     = -1;
-static int hf_mtp2_bib     = -1;
-static int hf_mtp2_fsn     = -1;
-static int hf_mtp2_fib     = -1;
-static int hf_mtp2_li      = -1;
-static int hf_mtp2_spare   = -1;
-static int hf_mtp2_sf      = -1;
-static int hf_mtp2_long_sf = -1;
+static int proto_mtp2        = -1;
+static int hf_mtp2_bsn       = -1;
+static int hf_mtp2_ext_bsn   = -1;
+static int hf_mtp2_ext_res   = -1;
+static int hf_mtp2_bib       = -1;
+static int hf_mtp2_ext_bib   = -1;
+static int hf_mtp2_fsn       = -1;
+static int hf_mtp2_ext_fsn   = -1;
+static int hf_mtp2_fib       = -1;
+static int hf_mtp2_ext_fib   = -1;
+static int hf_mtp2_li        = -1;
+static int hf_mtp2_ext_li    = -1;
+static int hf_mtp2_spare     = -1;
+static int hf_mtp2_ext_spare = -1;
+static int hf_mtp2_sf        = -1;
+static int hf_mtp2_long_sf   = -1;
 
 /* Initialize the subtree pointers */
 static gint ett_mtp2       = -1;
 
 static dissector_handle_t mtp3_handle;
 static int mtp3_proto_id;
-
-#define BSN_BIB_LENGTH 1
-#define FSN_FIB_LENGTH 1
-#define LI_LENGTH      1
-#define HEADER_LENGTH  (BSN_BIB_LENGTH + FSN_FIB_LENGTH + LI_LENGTH)
-
-#define BSN_BIB_OFFSET 0
-#define FSN_FIB_OFFSET (BSN_BIB_OFFSET + BSN_BIB_LENGTH)
-#define LI_OFFSET      (FSN_FIB_OFFSET + FSN_FIB_LENGTH)
-#define SIO_OFFSET     (LI_OFFSET + LI_LENGTH)
-
-#define BSN_MASK       0x7f
-#define BIB_MASK       0x80
-#define FSN_MASK       0x7f
-#define FIB_MASK       0x80
-#define LI_MASK        0x3f
-#define SPARE_MASK     0xc0
+static gboolean use_extended_sequence_numbers = FALSE;
+
+#define BSN_BIB_LENGTH          1
+#define FSN_FIB_LENGTH          1
+#define LI_LENGTH               1
+#define HEADER_LENGTH           (BSN_BIB_LENGTH + FSN_FIB_LENGTH + LI_LENGTH)
+
+#define EXTENDED_BSN_BIB_LENGTH 2
+#define EXTENDED_FSN_FIB_LENGTH 2
+#define EXTENDED_LI_LENGTH      2
+#define EXTENDED_HEADER_LENGTH  (EXTENDED_BSN_BIB_LENGTH + EXTENDED_FSN_FIB_LENGTH + EXTENDED_LI_LENGTH)
+
+#define BSN_BIB_OFFSET          0
+#define FSN_FIB_OFFSET          (BSN_BIB_OFFSET + BSN_BIB_LENGTH)
+#define LI_OFFSET               (FSN_FIB_OFFSET + FSN_FIB_LENGTH)
+#define SIO_OFFSET              (LI_OFFSET + LI_LENGTH)
+
+#define EXTENDED_BSN_BIB_OFFSET 0
+#define EXTENDED_FSN_FIB_OFFSET (EXTENDED_BSN_BIB_OFFSET + EXTENDED_BSN_BIB_LENGTH)
+#define EXTENDED_LI_OFFSET      (EXTENDED_FSN_FIB_OFFSET + EXTENDED_FSN_FIB_LENGTH)
+#define EXTENDED_SIO_OFFSET     (EXTENDED_LI_OFFSET + EXTENDED_LI_LENGTH)
+
+#define BSN_MASK                0x7f
+#define BIB_MASK                0x80
+#define FSN_MASK                0x7f
+#define FIB_MASK                0x80
+#define LI_MASK                 0x3f
+#define SPARE_MASK              0xc0
+
+#define EXTENDED_BSN_MASK       0x0fff
+#define EXTENDED_RES_MASK       0x7000
+#define EXTENDED_BIB_MASK       0x8000
+#define EXTENDED_FSN_MASK       0x0fff
+#define EXTENDED_FIB_MASK       0x8000
+#define EXTENDED_LI_MASK        0x01ff
+#define EXTENDED_SPARE_MASK     0xfe00
 
 static void
 dissect_mtp2_header(tvbuff_t *su_tvb, proto_item *mtp2_tree)
 {
   if (mtp2_tree) {
-    proto_tree_add_item(mtp2_tree, hf_mtp2_bsn,   su_tvb, BSN_BIB_OFFSET, BSN_BIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
-    proto_tree_add_item(mtp2_tree, hf_mtp2_bib,   su_tvb, BSN_BIB_OFFSET, BSN_BIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
-    proto_tree_add_item(mtp2_tree, hf_mtp2_fsn,   su_tvb, FSN_FIB_OFFSET, FSN_FIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
-    proto_tree_add_item(mtp2_tree, hf_mtp2_fib,   su_tvb, FSN_FIB_OFFSET, FSN_FIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
-    proto_tree_add_item(mtp2_tree, hf_mtp2_li,    su_tvb, LI_OFFSET,      LI_LENGTH,      LITTLE_ENDIAN_BYTE_ORDER);
-    proto_tree_add_item(mtp2_tree, hf_mtp2_spare, su_tvb, LI_OFFSET,      LI_LENGTH,      LITTLE_ENDIAN_BYTE_ORDER);
+    if (use_extended_sequence_numbers) {
+      proto_tree_add_item(mtp2_tree, hf_mtp2_ext_bsn,   su_tvb, EXTENDED_BSN_BIB_OFFSET, EXTENDED_BSN_BIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_ext_res,   su_tvb, EXTENDED_BSN_BIB_OFFSET, EXTENDED_BSN_BIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_ext_bib,   su_tvb, EXTENDED_BSN_BIB_OFFSET, EXTENDED_BSN_BIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_ext_fsn,   su_tvb, EXTENDED_FSN_FIB_OFFSET, EXTENDED_FSN_FIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_ext_res,   su_tvb, EXTENDED_BSN_BIB_OFFSET, EXTENDED_BSN_BIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_ext_fib,   su_tvb, EXTENDED_FSN_FIB_OFFSET, EXTENDED_FSN_FIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_ext_li,    su_tvb, EXTENDED_LI_OFFSET,      EXTENDED_LI_LENGTH,      LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_ext_spare, su_tvb, EXTENDED_LI_OFFSET,      EXTENDED_LI_LENGTH,      LITTLE_ENDIAN_BYTE_ORDER);
+    } else {
+      proto_tree_add_item(mtp2_tree, hf_mtp2_bsn,   su_tvb, BSN_BIB_OFFSET, BSN_BIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_bib,   su_tvb, BSN_BIB_OFFSET, BSN_BIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_fsn,   su_tvb, FSN_FIB_OFFSET, FSN_FIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_fib,   su_tvb, FSN_FIB_OFFSET, FSN_FIB_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_li,    su_tvb, LI_OFFSET,      LI_LENGTH,      LITTLE_ENDIAN_BYTE_ORDER);
+      proto_tree_add_item(mtp2_tree, hf_mtp2_spare, su_tvb, LI_OFFSET,      LI_LENGTH,      LITTLE_ENDIAN_BYTE_ORDER);
+    }
   }
 }
 
@@ -101,24 +139,30 @@ static const value_string status_field_vals[] = {
   { 0,   NULL}
 };
 
-#define SF_OFFSET      (LI_OFFSET + LI_LENGTH)
-#define SF_LENGTH      1
-#define LONG_SF_LENGTH 2
+#define SF_OFFSET          (LI_OFFSET + LI_LENGTH)
+#define EXTENDED_SF_OFFSET (EXTENDED_LI_OFFSET + EXTENDED_LI_LENGTH)
+
+#define SF_LENGTH          1
+#define LONG_SF_LENGTH     2
 
 static void
 dissect_mtp2_lssu(tvbuff_t *su_tvb, packet_info *pinfo, proto_item *mtp2_tree)
 {
-  guint8  li;
-
   if (check_col(pinfo->cinfo, COL_INFO))
     col_set_str(pinfo->cinfo, COL_INFO, "LSSU ");
   
   if (mtp2_tree) {
-    li = tvb_get_guint8(su_tvb, LI_OFFSET);
-    if ((li & LI_MASK) == 1)
-      proto_tree_add_item(mtp2_tree, hf_mtp2_sf,      su_tvb, SF_OFFSET, SF_LENGTH,      LITTLE_ENDIAN_BYTE_ORDER);
-    else
-      proto_tree_add_item(mtp2_tree, hf_mtp2_long_sf, su_tvb, SF_OFFSET, LONG_SF_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+    if (use_extended_sequence_numbers) {
+      if ((tvb_get_letohs(su_tvb, EXTENDED_LI_OFFSET) & EXTENDED_LI_MASK) == 1)
+        proto_tree_add_item(mtp2_tree, hf_mtp2_sf,      su_tvb, EXTENDED_SF_OFFSET, SF_LENGTH,      LITTLE_ENDIAN_BYTE_ORDER);
+      else
+        proto_tree_add_item(mtp2_tree, hf_mtp2_long_sf, su_tvb, EXTENDED_SF_OFFSET, LONG_SF_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+    } else {
+      if ((tvb_get_guint8(su_tvb, LI_OFFSET) & LI_MASK) == 1)
+        proto_tree_add_item(mtp2_tree, hf_mtp2_sf,      su_tvb, SF_OFFSET,          SF_LENGTH,      LITTLE_ENDIAN_BYTE_ORDER);
+      else
+        proto_tree_add_item(mtp2_tree, hf_mtp2_long_sf, su_tvb, SF_OFFSET,          LONG_SF_LENGTH, LITTLE_ENDIAN_BYTE_ORDER);
+    }
   }
 }
 
@@ -131,23 +175,34 @@ dissect_mtp2_msu(tvbuff_t *su_tvb, packet_info *pinfo, proto_item *mtp2_item, pr
   if (check_col(pinfo->cinfo, COL_INFO))
     col_set_str(pinfo->cinfo, COL_INFO, "MSU ");
 
-  sif_sio_length = tvb_length(su_tvb) - HEADER_LENGTH;
-  sif_sio_tvb = tvb_new_subset(su_tvb, SIO_OFFSET, sif_sio_length, sif_sio_length);
+  if (use_extended_sequence_numbers) {
+    sif_sio_length = tvb_length(su_tvb) - EXTENDED_HEADER_LENGTH;
+    sif_sio_tvb = tvb_new_subset(su_tvb, EXTENDED_SIO_OFFSET, sif_sio_length, sif_sio_length);
+  } else {
+    sif_sio_length = tvb_length(su_tvb) - HEADER_LENGTH;
+    sif_sio_tvb = tvb_new_subset(su_tvb, SIO_OFFSET, sif_sio_length, sif_sio_length);
+  }
   call_dissector(mtp3_handle, sif_sio_tvb, pinfo, tree);
 
-  if (tree)
-    proto_item_set_len(mtp2_item, HEADER_LENGTH);
-
+  if (tree) {
+    if (use_extended_sequence_numbers)
+      proto_item_set_len(mtp2_item, EXTENDED_HEADER_LENGTH);
+    else
+      proto_item_set_len(mtp2_item, HEADER_LENGTH);
+  }
 }
 
 static void
 dissect_mtp2_su(tvbuff_t *su_tvb, packet_info *pinfo, proto_item *mtp2_item, proto_item *mtp2_tree, proto_tree *tree)
 {
-  guint8 li;
+  guint16 li;
 
   dissect_mtp2_header(su_tvb, mtp2_tree);
-  li = tvb_get_guint8(su_tvb, LI_OFFSET);
-  switch(li & LI_MASK) {
+  if (use_extended_sequence_numbers)
+    li = tvb_get_letohs(su_tvb, EXTENDED_LI_OFFSET) & EXTENDED_LI_MASK;
+  else
+    li = tvb_get_guint8(su_tvb, LI_OFFSET) & LI_MASK;
+  switch(li) {
   case 0:
     dissect_mtp2_fisu(pinfo);
     break;
@@ -183,25 +238,42 @@ proto_register_mtp2(void)
 {
 
   static hf_register_info hf[] = {
-    { &hf_mtp2_bsn,     { "Backward sequence number", "mtp2.bsn",   FT_UINT8,  BASE_DEC, NULL,                    BSN_MASK,   "", HFILL } },
-    { &hf_mtp2_bib,     { "Backward indicator bit",   "mtp2.bib",   FT_UINT8,  BASE_DEC, NULL,                    BIB_MASK,   "", HFILL } },
-    { &hf_mtp2_fsn,     { "Forward sequence number",  "mtp2.fsn",   FT_UINT8,  BASE_DEC, NULL,                    FSN_MASK,   "", HFILL } },
-    { &hf_mtp2_fib,     { "Forward indicator bit",    "mtp2.fib",   FT_UINT8,  BASE_DEC, NULL,                    FIB_MASK,   "", HFILL } },
-    { &hf_mtp2_li,      { "Length Indicator",         "mtp2.li",    FT_UINT8,  BASE_DEC, NULL,                    LI_MASK,    "", HFILL } },
-    { &hf_mtp2_spare,   { "Spare",                    "mtp2.spare", FT_UINT8,  BASE_DEC, NULL,                    SPARE_MASK, "", HFILL } },
-    { &hf_mtp2_sf,      { "Status field",             "mtp2.sf",    FT_UINT8,  BASE_DEC, VALS(status_field_vals), 0x0,        "", HFILL } },
-    { &hf_mtp2_long_sf, { "Status field",             "mtp2.sf",    FT_UINT16, BASE_HEX, NULL,                    0x0,        "", HFILL } }
+    { &hf_mtp2_bsn,       { "Backward sequence number", "mtp2.bsn",   FT_UINT8,  BASE_DEC, NULL,                    BSN_MASK,            "", HFILL } },
+    { &hf_mtp2_ext_bsn,   { "Backward sequence number", "mtp2.bsn",   FT_UINT16, BASE_DEC, NULL,                    EXTENDED_BSN_MASK,   "", HFILL } },
+    { &hf_mtp2_ext_res,   { "Reserved",                 "mtp2.res",   FT_UINT16, BASE_DEC, NULL,                    EXTENDED_RES_MASK,   "", HFILL } },
+    { &hf_mtp2_bib,       { "Backward indicator bit",   "mtp2.bib",   FT_UINT8,  BASE_DEC, NULL,                    BIB_MASK,            "", HFILL } },
+    { &hf_mtp2_ext_bib,   { "Backward indicator bit",   "mtp2.bib",   FT_UINT16, BASE_DEC, NULL,                    EXTENDED_BIB_MASK,   "", HFILL } },
+    { &hf_mtp2_fsn,       { "Forward sequence number",  "mtp2.fsn",   FT_UINT8,  BASE_DEC, NULL,                    FSN_MASK,            "", HFILL } },
+    { &hf_mtp2_ext_fsn,   { "Forward sequence number",  "mtp2.fsn",   FT_UINT16, BASE_DEC, NULL,                    EXTENDED_FSN_MASK,   "", HFILL } },
+    { &hf_mtp2_fib,       { "Forward indicator bit",    "mtp2.fib",   FT_UINT8,  BASE_DEC, NULL,                    FIB_MASK,            "", HFILL } },
+    { &hf_mtp2_ext_fib,   { "Forward indicator bit",    "mtp2.fib",   FT_UINT16, BASE_DEC, NULL,                    EXTENDED_FIB_MASK,   "", HFILL } },
+    { &hf_mtp2_li,        { "Length Indicator",         "mtp2.li",    FT_UINT8,  BASE_DEC, NULL,                    LI_MASK,             "", HFILL } },
+    { &hf_mtp2_ext_li,    { "Length Indicator",         "mtp2.li",    FT_UINT16, BASE_DEC, NULL,                    EXTENDED_LI_MASK,    "", HFILL } },
+    { &hf_mtp2_spare,     { "Spare",                    "mtp2.spare", FT_UINT8,  BASE_DEC, NULL,                    SPARE_MASK,          "", HFILL } },
+    { &hf_mtp2_ext_spare, { "Spare",                    "mtp2.spare", FT_UINT16, BASE_DEC, NULL,                    EXTENDED_SPARE_MASK, "", HFILL } },
+    { &hf_mtp2_sf,        { "Status field",             "mtp2.sf",    FT_UINT8,  BASE_DEC, VALS(status_field_vals), 0x0,                 "", HFILL } },
+    { &hf_mtp2_long_sf,   { "Status field",             "mtp2.sf",    FT_UINT16, BASE_HEX, NULL,                    0x0,                 "", HFILL } }
   };
 
   static gint *ett[] = {
     &ett_mtp2
   };
 
+  module_t *mtp2_module;
+
   proto_mtp2 = proto_register_protocol("Message Transfer Part Level 2", "MTP2", "mtp2");
   register_dissector("mtp2", dissect_mtp2, proto_mtp2);
 
   proto_register_field_array(proto_mtp2, hf, array_length(hf));
   proto_register_subtree_array(ett, array_length(ett));
+  
+  mtp2_module = prefs_register_protocol(proto_mtp2, NULL);
+  prefs_register_bool_preference(mtp2_module, 
+                                 "use_extended_sequence_numbers",
+                                 "Use extended sequence numbers",
+                                 "Whether the MTP2 dissector should use extended sequence numbers as described in Q.703, Annex A",
+                                 &use_extended_sequence_numbers);
+
 
 }