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Pascal Quantin changed bug 8841

What	Removed	Added
Status	UNCONFIRMED	CONFIRMED
Summary	dissect_per_normally_small_nonnegative_whole_number	PER normally small non-negative whole number decoding is wrong when >= 64
Ever confirmed		1

Comment # 8 on bug 8841 from Pascal Quantin

I read the X.691 spec again and you are right: in case "n" >= 64, then it
should be encoded as a semi-constrained whole number with "lb" equal to 0,
following the rules for length determinant.
The following patch *might* work for aligned variant, but I've not checked its
impact on unaligned variant:

Index: epan/dissectors/packet-per.c
===================================================================
--- epan/dissectors/packet-per.c    (r‚vision 50435)
+++ epan/dissectors/packet-per.c    (copie de travail)
@@ -63,6 +63,7 @@
 static int hf_per_real_length = -1;
 static int hf_per_octet_string_length = -1;
 static int hf_per_bit_string_length = -1;
+static int hf_per_normally_small_nonnegative_whole_number_length = -1;
 static int hf_per_const_int_len = -1;
 static int hf_per_direct_reference = -1;          /* T_direct_reference */
 static int hf_per_indirect_reference = -1;        /* T_indirect_reference */
@@ -410,7 +411,7 @@
 dissect_per_normally_small_nonnegative_whole_number(tvbuff_t *tvb, guint32
offset, asn1_ctx_t *actx, proto_tree *tree, int hf_index, guint32 *length)
 {
     gboolean small_number, length_bit;
-    guint32 len;
+    guint32 len, length_determinant;
     proto_item *pi;

 DEBUG_ENTRY("dissect_per_normally_small_nonnegative_whole_number");
@@ -439,7 +440,37 @@
     }

     /* 10.6.2 */
-    offset=dissect_per_length_determinant(tvb, offset, actx, tree, hf_index,
length);
+    offset=dissect_per_length_determinant(tvb, offset, actx, tree,
hf_per_normally_small_nonnegative_whole_number_length, &length_determinant);
+    switch (length_determinant) {
+        case 0:
+            *length = 0;
+            break;
+        case 1:
+            *length = tvb_get_bits8(tvb, offset, 8);
+            offset += 8;
+            break;
+        case 2:
+            *length = tvb_get_bits16(tvb, offset, 16, ENC_BIG_ENDIAN);
+            offset += 16;
+            break;
+        case 3:
+            *length = tvb_get_bits32(tvb, offset, 24, ENC_BIG_ENDIAN);
+            offset += 24;
+            break;
+        case 4:
+            *length = tvb_get_bits32(tvb, offset, 32, ENC_BIG_ENDIAN);
+            offset += 32;
+            break;
+        default:
+            PER_NOT_DECODED_YET("too long
integer(per_normally_small_nonnegative_whole_number)");
+            offset += 8*length_determinant;
+            *length = 0;
+            return offset;
+    }
+    if(hf_index!=-1){
+        pi = proto_tree_add_uint(tree, hf_index, tvb,
(offset-(8*length_determinant))>>3, offset>>3, *length);
+        if (!display_internal_per_fields) PROTO_ITEM_SET_HIDDEN(pi);
+    }

     return offset;
 }
@@ -1079,7 +1110,7 @@
     /* gassert here? */
     if(length>8){
 PER_NOT_DECODED_YET("too long integer (64b)");
-        length=4;
+        length=8;
     }

     val=0;
@@ -2526,6 +2557,9 @@
     { &hf_per_bit_string_length,
         { "Bit String Length", "per.bit_string_length", FT_UINT32, BASE_DEC,
         NULL, 0, "Number of bits in the Bit String", HFILL }},
+    { &hf_per_normally_small_nonnegative_whole_number_length,
+        { "Normally Small Non-negative Whole Number Length",
"per.normally_small_nonnegative_whole_number_length", FT_UINT32, BASE_DEC,
+        NULL, 0, "Number of bytes in the Normally Small Non-negative Whole
Number", HFILL }},
     { &hf_per_const_int_len,
         { "Constrained Integer Length", "per.const_int_len", FT_UINT32,
BASE_DEC,
         NULL, 0, "Number of bytes in the Constrained Integer", HFILL }},

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