Risto Paasila skrev 2011-05-03 03:13:
Hi,
I have an issue with asn2wrs.
In the ASN file, I have for example this definition:
correlationID [0] IMPLICIT OCTET STRING (SIZE(14))
This by default gets compiled into the following code:
{&hf_ivrasn_correlationID,
{ "correlationID", "ivrasn.correlationID",
FT_BYTES, BASE_NONE, NULL, 0,
"OCTET_STRING_SIZE_14", HFILL }},
And of course when the data is displayed, the string is in hex.
I have added an entry in the conformance file, and the debug output of
the compiler shows the following :
# Conformance values
File Line Table Key Value
----------------------------------------------------------------------------------------------------
./myasn.cnf 11 PDU MessageType {'export':
False, 'new': False, 'hidden': False, 'need_decl':False, 'reg': None}
./myasn.cnf 131 TYPE_ATTR OCTET_STRING_SIZE_14 {'TYPE':
'FT_STRING', 'DISPLAY': 'BASE_NONE'}
./myasn.cnf 128 TYPE_ATTR correlationID {'TYPE':
'FT_STRING', 'DISPLAY': 'BASE_NONE'}
./myasn.cnf 127 TYPE_ATTR errorCode {'TYPE':
'FT_INT32', 'DISPLAY': 'BASE_DEC', 'STRINGS': 'VALS(errorCodeNames)'}
./myasn.cnf 126 TYPE_ATTR operationCode {'TYPE':
'FT_INT32', 'DISPLAY': 'BASE_DEC', 'STRINGS':
'VALS(myOperationNames)'}
./myasn.cnf 130 TYPE_ATTR uIScriptResult {'TYPE':
'FT_STRING', 'DISPLAY': 'BASE_NONE'}
./myasn.cnf 129 TYPE_ATTR uIScriptSpecificInformation
{'TYPE': 'FT_STRING', 'DISPLAY': 'BASE_NONE'}
However, it still does the default code generation, and the output is hex.
The generated code should be something like the following, so that the
dissector display is in ascii text:
{&hf_myasn_correlationID,
{ "correlationID", "myasn.correlationID",
FT_STRING, BASE_NONE, NULL, 0,
"OCTET_STRING_SIZE_14", HFILL }},
So is there some other trick I may have missed?
Many thanks,
Risto
OCTET STRING means a sequence of octets opaque to the protocol nothing
to do with STRING as in text.
an implementation of the protocol can chose to put text in an OCTET STRING.
For example UserID := OCTET STRING can contain 0xfffff or "MyID".
You can use #.TYPE_ATTR to change hf definition but formally you should
probably put code in the conformance
file to check if the OCTET STRING contains printable characters and then
output it as a string. Unless theres
is something in the protocol description saying that the OCTET STRING
should contain text there is no
guarantee that it will.
Regards
Andes
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