URL:
https://code.wireshark.org/review/gitweb?p=wireshark.git;a=commit;h=2046666b970ff37353a6776d2d903bff5ee36d1a
Submitter: "Anders Broman <a.broma...@gmail.com>"
Changed: branch: master
Repository: wireshark
Commits:
2046666 by Vadim Yanitskiy (vyanits...@sysmocom.de):
csn1: fix M_UINT_OFFSET: show value after applying the offset
Some integer fields in CSN.1 structures can be encoded with an offset.
A good example is GPRS Mobile Allocation IE defined in 3GPP TS 44.060,
section 12.10a, table 12.10a.1:
< GPRS Mobile Allocation IE > ::=
< HSN : bit (6) >
{ 0 | 1 < RFL number list : < RFL number list struct > > }
{ 0 < MA_LENGTH : bit (6) >
< MA_BITMAP : bit (val(MA_LENGTH) + 1) >
| 1 { 0 | 1 < ARFCN index list : < ARFCN index list struct > > }
} ;
so in this case the variable-length MA_BITMAP is defined as follows:
< MA_BITMAP : bit (val(MA_LENGTH) + 1) >
what basically means that its bit length shall be encoded with
a negative offset 1, therefore the following statements apply:
MA_LENGTH=0 defines MA_BITMAP of bit length 1
MA_LENGTH=1 defines MA_BITMAP of bit length 2
...
MA_LENGTH=63 defines MA_BITMAP of bit length 64
== What's wrong? ==
For some reason, Wireshark shows the raw values without applying
the offset. Here is an example of GPRS Mobile Allocation IE:
GPRS_Mobile_Allocation
.... .101 010. .... = HSN: 42
...0 .... = RFL_NUMBER Exist: 0
.... 0... = Mobile Allocation: (Union)
u.MA
.... .001 111. .... = Bit length: 15
...0 .... = Bitmap: 0 // 1st
.... 1... = Bitmap: 1
.... .0.. = Bitmap: 0
.... ..1. = Bitmap: 1
.... ...0 = Bitmap: 0
1... .... = Bitmap: 1
.0.. .... = Bitmap: 0
..1. .... = Bitmap: 1 // 8th
...0 .... = Bitmap: 0
.... 1... = Bitmap: 1
.... .0.. = Bitmap: 0
.... ..1. = Bitmap: 1
.... ...0 = Bitmap: 0
1... .... = Bitmap: 1
.0.. .... = Bitmap: 0
..1. .... = Bitmap: 1 // 16th
== Solution ==
Let's use proto_tree_add_uint_bits_format_value(), so we can print
the final value with the offset applied, as well as the original
one and the offset itself:
GPRS_Mobile_Allocation
.... .101 010. .... = HSN: 42
...0 .... = RFL_NUMBER Exist: 0
.... 0... = Mobile Allocation: (Union)
u.MA
.... .001 111. .... = Bit length: 16 (Raw 15 + Offset 1)
Change-Id: Ic4eaf2d8a3c2fedca855726e4175ddf47d16c5af
Reviewed-on: https://code.wireshark.org/review/37931
Petri-Dish: Anders Broman <a.broma...@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broma...@gmail.com>
Actions performed:
from 26c4120 GTP: extend TPDU Heuristic for ethernet frames
add 2046666 csn1: fix M_UINT_OFFSET: show value after applying the
offset
Summary of changes:
epan/dissectors/packet-csn1.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
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