Adding upstream version 4.2.2.upstream/4.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 2108 insertions, 0 deletions

diff --git a/epan/dissectors/asn1/atn-ulcs/CMakeLists.txt b/epan/dissectors/asn1/atn-ulcs/CMakeLists.txt
new file mode 100644
index 00000000..c95e8025
--- /dev/null
+++ b/epan/dissectors/asn1/atn-ulcs/CMakeLists.txt
@@ -0,0 +1,41 @@
+# CMakeLists.txt
+#
+# Wireshark - Network traffic analyzer
+# By Gerald Combs <gerald@wireshark.org>
+# Copyright 1998 Gerald Combs
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+
+set( PROTOCOL_NAME atn-ulcs )
+
+set( PROTO_OPT )
+
+set( EXPORT_FILES
+)
+
+set( EXT_ASN_FILE_LIST
+)
+
+set( ASN_FILE_LIST
+	${PROTOCOL_NAME}.asn
+)
+
+set( EXTRA_DIST
+	${ASN_FILE_LIST}
+	packet-${PROTOCOL_NAME}-template.c
+	packet-${PROTOCOL_NAME}-template.h
+	${PROTOCOL_NAME}.cnf
+)
+
+set( SRC_FILES
+	${EXTRA_DIST}
+	${EXT_ASN_FILE_LIST}
+)
+
+set( A2W_FLAGS -u )
+
+set( EXTRA_CNF
+)
+
+ASN2WRS()
diff --git a/epan/dissectors/asn1/atn-ulcs/atn-ulcs.asn b/epan/dissectors/asn1/atn-ulcs/atn-ulcs.asn
new file mode 100644
index 00000000..de9b94e6
--- /dev/null
+++ b/epan/dissectors/asn1/atn-ulcs/atn-ulcs.asn
@@ -0,0 +1,508 @@
+-- File: atn-ulcs.asn
+-- Sub-Volume IV ASN.1 reference definitions for ICAO Doc. 9705,
+-- Second Edition
+-- Version 1.1, 03 Oct 2001
+
+-- The majority of the ULCS protocol definitions are specified in the ULCS
+-- Technical Provisions by reference to ISO/IEC Standards and/or ITU-T
+-- Recommendations.  The ASN.1 definitions are reproduced here for ease of
+-- reference and to allow explanatory annotations to be added. In the case of
+-- any discrepancy between the definitions here and the corresponding
+-- definitions defined in or referenced by the ULCS Technical Provisions,
+-- the latter are assumed to take precedence.
+
+-- The following ASN.1 modules are included here:
+
+-- * General ULCS types.  These are ASN.1 definitions used in the ULCS
+-- Technical Provisions, though there is no equivalent ASN.1 module
+-- defined there.  The definitions in this module would generally be
+-- incorporated into a wider "user" protocol module if using ASN.1 automated
+-- tools.  They are defined in a separate module here so that their syntax can
+-- easily be verified by an ASN.1 syntax checker.
+
+-- * Connection-oriented ACSE definitions.  This is equivalent to the "ACSE-1"
+-- module defined in the connection-oriented ACSE protocol standard.
+
+-- * Information Framework.  This is an extract of relevant definitions from the
+-- InformationFramework module in the OSI standard "Directory : Models".  The
+-- types defined in this module are not actively used in the ULCS protocol, but
+-- they are needed to satisfy IMPORTS statements in the ACSE definitions, and
+-- to allow certain CHOICE types in the ACSE definitions to be sorted correctly
+-- into canonical order.
+
+
+-- Note.- In the following definitions, the ASN.1 comment " X" indicates
+-- choice elements and optional elements in sequence types that are defined as
+-- "Excluded" in the ULCS profile.  That is, implementations of ULCS provisions
+-- are never required to encode values for such elements (though they are
+-- required to indicate the absence of these elements in all instances, by means
+-- of bits in the appropriate PER preamble or choice index).
+
+
+-- General ULCS types
+
+ULCS DEFINITIONS ::= BEGIN
+--  ***************************************************************************
+--  The following ASN.1 definitions are from Doc 9705 Sub-Volume IV,
+--  section 4.3.2.6.2
+--  ***************************************************************************
+
+--Presentation User Data is Fully-encoded-data from
+--ISO/IEC 8823-1:1994/Amd.1:1997 | ITU-T Rec. X.226/Amd. 1
+
+--Fully-encoded-data ::= SEQUENCE SIZE (1, ...) OF PDV-list
+Fully-encoded-data ::= SEQUENCE SIZE (1, ..., 2..MAX) OF PDV-list
+-- contains one or more presentation-data-value-list (PDV-list) values
+-- ATN commentary: The SIZE constraint above differs from the referenced
+-- standard, which specifies (in 8.2):
+-- Fully-encoded-data ::= SEQUENCE SIZE (1, ..., 2..MAX) OF PDV-list.
+-- The ULCS provisions specify a simplified, but compatible, efficiency
+-- constraint as there will never be more than one element in the SEQUENCE OF
+-- for the foreseeable future.
+-- This simplifies matters for some compilers.
+
+PDV-list ::= SEQUENCE  {
+    transfer-syntax-name              Transfer-syntax-name OPTIONAL,       -- X
+    presentation-context-identifier   Presentation-context-identifier,
+    presentation-data-values          CHOICE
+    { single-ASN1-type  [0] ABSTRACT-SYNTAX.&Type
+        (CONSTRAINED BY {
+        -- Type corresponding to presentation context identifier -- }) , -- X
+            octet-aligned  [1] IMPLICIT OCTET STRING,    -- X
+            arbitrary      [2] IMPLICIT BIT STRING }
+    -- contains one or more presentation data values from the same
+    -- presentation context.
+    -- ATN Commentary: only the arbitrary BIT STRING encoding choice is used.
+}
+
+Transfer-syntax-name ::= OBJECT IDENTIFIER -- ATN: not used for ATN Upper Layers
+
+Presentation-context-identifier::= INTEGER  -- ATN: the following values are
+                                            -- ATN-specific
+{   acse-apdu     (1),
+    reserved      (2),
+    user-ase-apdu (3) } (1..127, ... )
+-- ATN commentary: The SIZE constraint above differs from the referenced
+-- standard, which specifies (in 8.2):
+-- Presentation-context-identifier::= INTEGER (1..127, ..., 128..MAX ).
+-- The ULCS provisions specify a simplified, but compatible, efficiency
+-- constraint as there will never be more than 127 presentation contexts in
+-- ATN for the foreseeable future.
+-- This simplifies matters for some compilers.  The list of defined values is
+-- shown here for guidance only, and has no effect on the PER encoding.
+
+
+END -- of ULCS definitions
+
+--  Connection-oriented ACSE definitions
+--*************************************************************************
+-- The ACSE abstract syntax from ISO/IEC 8650-1/Amd.1 | ITU-T Rec. X.227/
+-- Amd. 1 is reproduced here for ease of reference.  In case of any discrepancy,
+-- the ISO/IEC standard takes precedence.
+--*************************************************************************
+
+ACSE-1 {joint-iso-itu-t association-control(2) modules(0) apdus(0) version1(1)}
+--  ACSE-1 refers to ACSE version 1
+DEFINITIONS ::=
+BEGIN
+    EXPORTS
+      acse-as-id, ACSE-apdu, aCSE-id, Application-context-name, AP-title,
+      AE-qualifier, -- AE-title, (ATN: AE-title is not needed)
+      AP-invocation-identifier,
+      AE-invocation-identifier, Mechanism-name, Authentication-value,
+      ACSE-requirements;
+    IMPORTS    Name, RelativeDistinguishedName
+      FROM InformationFramework
+        { joint-iso-ccitt ds(5) module(1) informationFramework(1)  2 };
+      -- The data types Name and RelativeDistinguishedName are imported
+      -- from ISO/IEC 9594-2 | ITU-T Rec. X.501.
+      -- ATN Commentary: The relevant InformationFramework extracts are given
+      -- below.
+
+-- *************************************************************************
+--  EXTERNAL
+-- *************************************************************************
+
+-- EXTERNAL is an ASN.1 UNIVERSAL type.  The definition in the PER standard
+-- ISO/IEC 8825-2 | ITU-T Rec. X.691 is assumed for ACSE.
+-- The type is used in ACSE user-information
+-- fields.  ASN.1 compilers will not in general allow EXTERNAL to be
+-- redefined (therefore 'EXTERNALt'),
+-- and it is invalid ASN.1 to define a type with tag [UNIVERSAL 8]
+--
+-- Workaround for bug in asn2wrs in the .cnf file
+-- to handle the lack of support for tagged assignments.
+-- remove that workaround once asn2wrs learns how to handle
+-- tagged assignments.
+--
+EXTERNALt ::= [8] IMPLICIT SEQUENCE {
+    direct-reference    OBJECT IDENTIFIER   OPTIONAL,       -- X
+    indirect-reference  INTEGER             OPTIONAL,
+    data-value-descriptor    ObjectDescriptor    OPTIONAL,  -- X
+    encoding       CHOICE {
+        single-ASN1-type    [0] ABSTRACT-SYNTAX.&Type,
+        octet-aligned  [1] IMPLICIT OCTET STRING,            -- X
+        arbitrary [2] IMPLICIT BIT STRING }}
+--   ATN: implementations are advised to use arbitrary (BIT STRING)
+--   encodings only (see Guidance Material section 2.6.5.21).
+--   BIT STRING values are not padded to octet boundaries.
+
+
+-- object identifier assignments
+acse-as-id OBJECT IDENTIFIER ::=
+{joint-iso-itu-t association-control(2) abstract-syntax(1) apdus(0) version1(1)}
+     -- may be used to reference the abstract syntax of the ACSE APDUs
+aCSE-id OBJECT IDENTIFIER ::=
+{ joint-iso-itu-t association-control(2) ase-id(3) acse-ase(1) version(1) }
+     --  may be used to identify the Association Control ASE.
+
+-- top level CHOICE
+ACSE-apdu  ::=  CHOICE
+{
+    aarq      AARQ-apdu,     -- ACSE associate request pdu
+    aare      AARE-apdu,     -- ACSE associate response pdu
+    rlrq      RLRQ-apdu,     -- ACSE release request pdu
+    rlre      RLRE-apdu,     -- ACSE release response pdu
+    abrt      ABRT-apdu,     -- ACSE abort pdu
+    ...
+}
+
+AARQ-apdu  ::=  [ APPLICATION 0 ]  IMPLICIT SEQUENCE
+{   protocol-version                  [0] IMPLICIT BIT STRING { version1 (0) } DEFAULT { version1 }, -- X
+    application-context-name          [1] Application-context-name,
+    called-AP-title                   [2] AP-title                  OPTIONAL, -- X
+    called-AE-qualifier               [3] AE-qualifier              OPTIONAL, -- X
+    called-AP-invocation-identifier   [4] AP-invocation-identifier  OPTIONAL, -- X
+    called-AE-invocation-identifier   [5] AE-invocation-identifier  OPTIONAL, -- X
+    calling-AP-title                  [6] AP-title                  OPTIONAL,
+    calling-AE-qualifier              [7] AE-qualifier              OPTIONAL,
+    calling-AP-invocation-identifier  [8] AP-invocation-identifier  OPTIONAL, -- X
+    calling-AE-invocation-identifier  [9] AE-invocation-identifier  OPTIONAL, -- X
+    -- The following field is not present if only the Kernel is used.
+    -- ATN: For Doc 9705 ed 1/ed 2, only the Kernel is required.
+    sender-acse-requirements          [10]  IMPLICIT ACSE-requirements  OPTIONAL,
+    -- The following field is only present if the Authentication functional
+    -- unit is selected.  ATN: not used in Doc 9705 ed 1/ed 2.
+    mechanism-name                    [11]  IMPLICIT Mechanism-name   OPTIONAL,
+    -- The following field is only present if the Authentication functional
+    -- unit is selected.  ATN: use is deprecated in Doc 9705 ed 1/ed 2.
+    calling-authentication-value      [12]  EXPLICIT Authentication-value  OPTIONAL,
+    application-context-name-list     [13]  IMPLICIT Application-context-name-list  OPTIONAL, -- X
+    -- The above field is only present if the Application Context Negotiation
+    -- functional unit is selected - never for ATN
+    implementation-information        [29]  IMPLICIT Implementation-data  OPTIONAL, -- X
+    ..., ...,            -- ATN: Note use of extension marker pair
+    user-information             [30] IMPLICIT Association-information   OPTIONAL
+}
+
+
+AARE-apdu  ::=  [ APPLICATION 1 ]  IMPLICIT SEQUENCE
+{   protocol-version                    [0]   IMPLICIT BIT STRING{ version1 (0) }
+                                                      DEFAULT { version1 }, -- X
+    application-context-name            [1] Application-context-name,
+    result                              [2] Associate-result,
+    result-source-diagnostic            [3] Associate-source-diagnostic,
+    responding-AP-title                 [4] AP-title              OPTIONAL, -- X
+    responding-AE-qualifier             [5] AE-qualifier          OPTIONAL, -- X
+    responding-AP-invocation-identifier [6] AP-invocation-identifier  OPTIONAL, -- X
+    responding-AE-invocation-identifier [7] AE-invocation-identifier  OPTIONAL, -- X
+    -- The following field is not present if only the Kernel is used.
+    -- ATN: For Doc 9705 ed 1/ed 2, only the Kernel is required.
+    responder-acse-requirements         [8] IMPLICIT ACSE-requirements  OPTIONAL,
+    -- The following field is only present if the Authentication functional
+    -- unit is selected.  ATN: not used in Doc 9705 ed 1/ed 2.
+    mechanism-name                      [9] IMPLICIT Mechanism-name OPTIONAL,
+    -- The following field is only present if the Authentication functional
+    -- unit is selected.  ATN: use is deprecated in Doc 9705 ed 1/ed 2.
+    responding-authentication-value [10]  EXPLICIT  Authentication-value OPTIONAL,
+    application-context-name-list   [11]  IMPLICIT  Application-context-name-list
+                                                                      OPTIONAL, -- X
+    --  The above field is only present if the Application Context Negotiation
+    -- functional unit is selected - never for ATN
+    implementation-information    [29]  IMPLICIT  Implementation-data OPTIONAL, --X
+    ..., ...,   -- ATN: Note use of extension marker pair
+    user-information              [30]  IMPLICIT  Association-information OPTIONAL
+}
+
+
+RLRQ-apdu  ::=  [ APPLICATION 2 ] IMPLICIT SEQUENCE
+{   reason                      [0] IMPLICIT  Release-request-reason  OPTIONAL,
+    ..., ...,   -- ATN: Note use of extension marker pair
+    user-information            [30]  IMPLICIT Association-information  OPTIONAL
+}
+
+
+RLRE-apdu  ::=  [ APPLICATION 3 ] IMPLICIT SEQUENCE
+{   reason                      [0] IMPLICIT  Release-response-reason OPTIONAL,
+    ..., ..., -- ATN: Note use of extension marker pair
+    user-information            [30]  IMPLICIT  Association-information OPTIONAL
+}
+
+
+ABRT-apdu ::= [ APPLICATION 4 ] IMPLICIT SEQUENCE
+{   abort-source                [0]   IMPLICIT ABRT-source,
+    abort-diagnostic            [1]   IMPLICIT ABRT-diagnostic  OPTIONAL,
+    -- The above field is not present if only the Kernel is used.
+    -- ATN: For Doc 9705 ed 1/ed 2, only the Kernel is required.
+    ..., ...,     -- ATN: Note use of extension marker pair
+    user-information            [30]  IMPLICIT  Association-information OPTIONAL
+}
+
+
+ABRT-diagnostic ::= ENUMERATED
+{   no-reason-given (1),
+    protocol-error  (2),
+    authentication-mechanism-name-not-recognized (3),
+    authentication-mechanism-name-required (4),
+    authentication-failure (5),
+    authentication-required (6),
+    ... }
+
+ABRT-source   ::=   INTEGER { acse-service-user (0),  acse-service-provider (1)}  (0..1, ...)
+
+ACSE-requirements   ::=   BIT STRING
+{ authentication (0), application-context-negotiation(1) }
+-- ATN commentary: application-context-negotiation (bit 1) is
+-- never set for ATN ULCS.  Use of authentication is deprecated
+-- for Doc 9705 ed 1/ed 2.
+
+Application-context-name-list ::= SEQUENCE OF Application-context-name
+-- ATN Commentary: the above type is not used for ATN ULCS.
+
+Application-context-name ::= OBJECT IDENTIFIER
+
+--  ***************************************************************************
+--  Application-entity title productions follow (not in alphabetical order)
+--  ***************************************************************************
+-- MG: asn2wrs cannot handle untagged CHOICEs within either a SET or a SEQUENCE.
+-- https://gitlab.com/wireshark/wireshark/-/wikis/Asn2wrs_Handmassaging_the_ASN_file
+AP-title ::= CHOICE { -- ATN: See encoding guidance in 2.5.11
+                          -- "form2" is encoded as 0 and "form1" as 1
+    ap-title-form2 [0]  IMPLICIT  AP-title-form2,   -- Object Identifier form
+    ap-title-form1 [1]  IMPLICIT  AP-title-form1,   -- X (Directory name form)
+    ... }
+
+AE-qualifier ::= CHOICE {-- ATN: See encoding guidance in 2.5.11
+                          -- "form2" is encoded as 0 and "form1" as 1
+    ae-qualifier-form2  [0]  IMPLICIT   AE-qualifier-form2,   -- INTEGER form
+    ae-qualifier-form1  [1]  IMPLICIT   AE-qualifier-form1,   -- X (RDN form)
+    ... }
+-- ATN commentary: AE-qualifier is set to "app-type" in Doc 9705 1st and
+-- 2nd editions.  For forward compatibility, the value should not be
+-- analysed.
+
+--  When both AP-title and AE-qualifier data values are present in an AARQ or
+--  AARE APDU, both have the same form to allow the construction of an
+--  AE-title as discussed in CCITT Rec. X.665 | ISO/IEC 9834-6.
+
+AP-title-form1 ::= Name  -- ATN: Not used for ATN ULCS
+--   The value assigned to AP-title-form1 is The Directory Name of an
+--   application-process title.
+
+AE-qualifier-form1 ::= RelativeDistinguishedName  -- ATN: Not used for ULCS
+--   The value assigned to AE-qualifier-form1 is the relative distinguished name
+--   of a particular application-entity of the application-process identified by
+--   AP-title-form1.
+
+AP-title-form2 ::= OBJECT IDENTIFIER
+
+AE-qualifier-form2 ::= INTEGER
+
+-- ATN commentary: The AE-title productions below are commented out,
+-- as they are not required for ATN ULCS.
+-- AE-title ::= CHOICE {
+--     ae-title-form1    AE-title-form1,
+--     ae-title-form2    AE-title-form2,
+--     ... }
+--
+-- As defined in CCITT Rec. X.650 | ISO 7498-3, an application-entity title is
+-- composed of an application-process title and an application-entity qualifier.
+-- The ACSE protocol provides for the transfer of an application-entity title
+-- value by the transfer of its component values.  However, the following data
+-- type is provided for International Standards that reference a single
+-- syntactic structure for AE titles.  (Not used for ATN ULCS)
+--
+-- AE-title-form1 ::= Name
+--    For access to The Directory (ITU-T Rec. X.500-Series | ISO/IEC 9594), an
+--    AE title has AE-title-form1.
+--    This value can be constructed from AP-title-form1 and AE-qualifier-form1
+--    values contained in an AARQ or AARE APDU. A discussion of forming an
+--    AE-title-form1 from AP-title-form1 and AE-qualifier-form1 may be found in
+--    CCITT Rec. X.665 | ISO/IEC 9834-6.
+--
+-- AE-title-form2 ::= OBJECT IDENTIFIER
+--  A discussion of forming an AE-title-form2 from AP-title-form2 and
+--  AE-qualifier-form2 may be found in CCITT Rec. X.665 | ISO/IEC 9834-6.
+
+AE-invocation-identifier ::= INTEGER  -- ATN: not used in ULCS
+AP-invocation-identifier ::= INTEGER  -- ATN: not used in ULCS
+--  End of Application-entity title productions
+--  ***************************************************************************
+
+Associate-result  ::= INTEGER
+{   accepted              (0),
+    rejected-permanent    (1),
+    rejected-transient    (2)  } (0..2, ...)
+
+Associate-source-diagnostic  ::=  CHOICE
+{ acse-service-user           [1]  INTEGER
+    {   null  (0),
+        no-reason-given  (1),
+        application-context-name-not-supported  (2),
+        calling-AP-title-not-recognized  (3),
+        calling-AP-invocation-identifier-not-recognized  (4),
+        calling-AE-qualifier-not-recognized  (5),
+        calling-AE-invocation-identifier-not-recognized  (6),
+        called-AP-title-not-recognized  (7),
+        called-AP-invocation-identifier-not-recognized  (8),
+        called-AE-qualifier-not-recognized  (9),
+        called-AE-invocation-identifier-not-recognized  (10),
+        authentication-mechanism-name-not-recognized  (11),
+        authentication-mechanism-name-required  (12),
+        authentication-failure  (13),
+        authentication-required  (14)      }     (0..14 ,  ...),
+        acse-service-provider    [2]    INTEGER
+      {   null  (0),
+          no-reason-given  (1),
+          no-common-acse-version  (2) }    (0..2 , ...)
+}
+
+Association-information ::=  SEQUENCE SIZE (1, ..., 0 | 2..MAX) OF EXTERNALt
+-- ATN: No SIZE extensions are defined, only one EXTERNAL element is present
+
+
+
+Implementation-data ::=  OCTET STRING      -- ATN: Not used for ULCS
+
+Mechanism-name ::= OBJECT IDENTIFIER         -- ATN: Not used for ULCS
+
+MECHANISM-NAME ::=TYPE-IDENTIFIER  -- ATN: Not used for ULCS
+
+ObjectSet MECHANISM-NAME ::= {...}      -- ATN: Not used for ULCS
+
+Release-request-reason  ::= INTEGER {normal (0), urgent (1), user-defined (30)} (0 | 1 | 30, ...)
+
+Release-response-reason  ::= INTEGER {normal (0), not-finished (1), user-defined (30)} (0 | 1 | 30, ...)
+-- ATN commentary: For the above two types, see the encoding guidance in 2.5.10
+-- Values are encoded in 5 bits, not 3 as might be expected.
+
+Authentication-value  ::=   CHOICE      -- ATN: use is deprecated in ed 1/ed 2
+{   charstring   [0]  IMPLICIT OCTET STRING,
+    bitstring    [1]  IMPLICIT BIT STRING,
+    external     [2]  IMPLICIT EXTERNAL,
+    other        [3]  IMPLICIT SEQUENCE {
+--        other-mechanism-name  MECHANISM-NAME.&id ({ObjectSet}),
+          other-mechanism-name  OBJECT IDENTIFIER,
+--        other-mechanism-value  MECHANISM-NAME.&Type ({ObjectSet}{@.other-mechanism-name})
+          other-mechanism-value  ANY
+          }     -- X
+}
+-- The abstract syntax of (calling/responding) authentication-value is
+-- determined by the authentication mechanism used during association
+-- establishment.  The authentication mechanism is either explicitly
+-- denoted by the &id field (of type OBJECT IDENTIFIER) for a mechanism
+-- belonging to the class MECHANISM-NAME, or it is known implicitly by
+-- prior agreement between the communicating partners.  If the "other"
+-- component is chosen, then the "mechanism-name" component is present
+-- in accordance with ITU-T Rec. X.680|ISO/IEC 8824. If the value
+-- "mechanism-name" occurs in the AARQ-apdu or the AARE-apdu, then that
+-- value is the same as the value for "other-mechanism-name"
+END -- of Connection-Oriented ACSE definitions
+
+
+-- *************************************************************************
+-- The following definitions are adapted from the Directory standard
+-- ISO/IEC 9594-2:1993 | ITU-T Rec. X.501 (1993 E).  In case of any discrepancy,
+-- the ISO/IEC standard takes precedence.
+-- *************************************************************************
+
+InformationFramework {joint-iso-ccitt ds(5) module(1) informationFramework(1) 2}
+DEFINITIONS ::=
+BEGIN
+EXPORTS Name, RelativeDistinguishedName;
+
+Name     ::= CHOICE {rdnSequence  RDNSequence}
+-- only one CHOICE defined
+
+RDNSequence  ::= SEQUENCE OF RelativeDistinguishedName
+
+RelativeDistinguishedName ::= SET SIZE (1 .. MAX) OF AttributeTypeAndValue
+
+AttributeTypeAndValue ::= SEQUENCE {
+-- ATN commentary: The following line has been inserted to allow the Name and
+-- RelativeDistinguishedName types, as used by ACSE, to be resolved by an
+-- ASN.1 compiler, without introducing the unnecessary complexity
+-- Of the ATTRIBUTE information object class, which is used in the
+-- Directory standards.
+      null NULL}
+-- The "real" components of AttributeTypeAndValue follow.  They have been
+-- commented out here, but could be restored if required, for example, for
+-- sharing data types with a Directory implementation.  The syntax has been
+-- verified by the OSS syntax checker.
+--   type      ATTRIBUTE.&id ({SupportedAttributes}),
+--   value     ATTRIBUTE.&Type ({SupportedAttributes} {@type})
+--}
+
+--SupportedAttributes    ATTRIBUTE ::=
+--   {objectClass | aliasedEntryName, ...}
+
+-- ATN Commentary: ATTRIBUTE is an information object class, specified in
+-- ISO/IEC 9594-2 | ITU-T Rec. X.501, using the notation defined in
+-- ISO/IEC 8824-2 | ITU-T Rec. X.681.  However, for ULCS implementation, it
+-- is only necessary to note that the ACSE CHOICE types AP-title,
+-- AE-qualifier and AE-title are all constrained to be the "form 2" variants,
+-- with types Object Identifier, Integer and Object Identifier, respectively.
+-- It is however necessary to know the syntax of the "form 1" variants (Name,
+-- RelativeDistinguishedName and Name, respectively) so that the CHOICE
+-- elements can be sorted into canonical order, based on their ASN.1 types,
+-- for PER encoding (see 2.5.11).
+--
+--ATTRIBUTE    ::= CLASS {
+--   &derivation    ATTRIBUTE OPTIONAL,
+--   &Type                         OPTIONAL,
+--   &equality-match     MATCHING-RULE  OPTIONAL,
+--   &ordering-match     MATCHING-RULE  OPTIONAL,
+--   &substrings-match   MATCHING-RULE  OPTIONAL,
+--   &single-valued BOOLEAN   DEFAULT FALSE,
+--   &collective    BOOLEAN   DEFAULT FALSE,
+--   &no-user-modification    BOOLEAN DEFAULT FALSE,
+--   &usage         AttributeUsage DEFAULT userApplications,
+--   &id            OBJECT IDENTIFIER UNIQUE }
+--
+--MATCHING-RULE     ::= CLASS {
+--   &AssertionType      OPTIONAL,
+--   &id            OBJECT IDENTIFIER UNIQUE }
+
+--objectClass ATTRIBUTE ::= {
+--   &Type          OBJECT IDENTIFIER,
+--   &id            id-at-objectClass
+--}
+--
+--aliasedEntryName ATTRIBUTE ::= {
+--   &Type          OBJECT IDENTIFIER,
+--   &id            id-at-aliasedEntryName
+--}
+--
+--AttributeUsage ::= ENUMERATED {
+--   userApplications (0),
+--   directoryOperation (1),
+--   distributedOperation (2),
+--   dSAOperation (3) }
+--
+--id-at-objectClass           OBJECT IDENTIFIER ::= {id-at 0}
+--id-at-aliasedEntryName OBJECT IDENTIFIER ::= {id-at 1}
+--id-at        OBJECT IDENTIFIER ::= {joint-iso-ccitt ds(5) attributeType(4)}
+
+END -- of Directory Information Framework extracts
+--
+-- Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+--
+-- Local variables:
+-- c-basic-offset: 4
+-- tab-width: 8
+-- indent-tabs-mode: nil
+-- End:
+--
+-- vi: set shiftwidth=4 tabstop=8 expandtab:
+-- :indentSize=4:tabSize=8:noTabs=true:
+--
diff --git a/epan/dissectors/asn1/atn-ulcs/atn-ulcs.cnf b/epan/dissectors/asn1/atn-ulcs/atn-ulcs.cnf
new file mode 100644
index 00000000..793a4509
--- /dev/null
+++ b/epan/dissectors/asn1/atn-ulcs/atn-ulcs.cnf
@@ -0,0 +1,587 @@
+#.MODULE_IMPORT
+
+#.FIELD_RENAME
+AARQ-apdu/protocol-version  aarq-apdu_protocol-version
+AARE-apdu/protocol-version  aare-apdu_protocol-version
+RLRE-apdu/reason  rlre-apdu_response_reason
+RLRQ-apdu/reason  rlrq-apdu_request_reason
+EXTERNALt/encoding/single-ASN1-type externalt_encoding_single-asn1-type
+EXTERNALt/encoding/arbitrary  externalt_encoding_arbitrary
+EXTERNALt/encoding/octet-aligned  externalt_encoding_octet-aligned
+PDV-list/presentation-data-values/single-ASN1-type  pdv-list_presentation-data-values_single-asn1-type
+PDV-list/presentation-data-values/arbitrary pdv-list_presentation-data-values_arbitrary
+#.END
+
+#.PDU
+  Fully-encoded-data
+  ACSE-apdu
+#.END
+
+
+#.FN_PARS Release-request-reason
+  VAL_PTR=&reason
+#.END
+
+
+#.FN_BODY Presentation-context-identifier
+
+    offset = dissect_per_constrained_integer(
+        tvb,
+        offset,
+        actx,
+        tree,
+        hf_index,
+        1U,
+        127U,
+        &ulcs_context_value,
+        TRUE);
+
+#.END
+
+#.FN_BODY PDV-list/presentation-data-values/arbitrary
+
+    packet_info * pinfo = actx->pinfo;
+    tvbuff_t *tvb_usr = NULL;
+    proto_tree *atn_ulcs_tree = NULL;
+    atn_conversation_t *atn_cv = NULL;
+    heur_dtbl_entry_t *hdtbl_entry;
+
+    /* extract bitstring into new tvb buffer */
+    offset = dissect_per_bit_string(
+        tvb,
+        offset,
+        actx,
+        tree,
+        hf_index,
+        NO_BOUND,
+        NO_BOUND,
+        FALSE,
+        NULL,
+        0,
+        &tvb_usr,
+        NULL);
+
+    if (tvb_usr) {
+      /* call appropiate dissector for bitstring data */
+      switch(ulcs_context_value){
+          case  1: /* ACSE PDU*/
+              atn_ulcs_tree = proto_tree_add_subtree(
+                  root_tree, tvb, offset, 0,
+                  ett_atn_acse, NULL, ATN_ACSE_PROTO );
+
+              dissect_ACSE_apdu_PDU(
+                  tvb_new_subset_remaining(tvb_usr, 0),
+                  pinfo,
+                  atn_ulcs_tree, NULL);
+              break;
+            case  3: /* USER data; call subdissector for CM, CPDLC ...  */
+
+                /* using dstref for PDV-list only occurrs in DT */
+                atn_cv = find_atn_conversation(
+                    &pinfo->dst,
+                    pinfo->clnp_dstref,
+                    &pinfo->src);
+
+                if(atn_cv) {
+                    switch(atn_cv->ae_qualifier){
+                        case cma: /* contact management */
+                            call_dissector_with_data(
+                                atn_cm_handle,
+                                tvb_new_subset_remaining(tvb_usr, 0),
+                                pinfo,
+                                root_tree,
+                                NULL);
+                            break;
+                        case cpdlc: /* plain old cpdlc */
+                        case pmcpdlc: /* protected mode cpdlc */
+                            call_dissector_with_data(
+                                atn_cpdlc_handle,
+                                tvb_new_subset_remaining(tvb_usr, 0),
+                                pinfo,
+                                root_tree,
+                                NULL);
+                            break;
+                        default: /* unknown or unhandled datalink application */
+                            dissector_try_heuristic(
+                                atn_ulcs_heur_subdissector_list,
+                                tvb_new_subset_remaining(tvb_usr,0),
+                                actx->pinfo,
+                                root_tree,
+                                &hdtbl_entry,
+                                NULL);
+                            break;
+                    }
+                }
+                else{
+                    dissector_try_heuristic(
+                        atn_ulcs_heur_subdissector_list,
+                        tvb_new_subset_remaining(tvb_usr,0),
+                        actx->pinfo,
+                        root_tree,
+                        &hdtbl_entry,
+                        NULL);
+                }
+                break;
+            default:
+                break;
+      } /* switch(ulcs_context_value) */
+    }
+
+#.END
+
+
+#.FN_BODY Authentication-value/other/other-mechanism-value
+
+    offset=call_ber_oid_callback(
+        object_identifier_id,
+        tvb,
+        offset,
+        actx->pinfo,
+        tree, NULL);
+
+#.END
+
+#.FN_BODY       Mechanism-name
+
+    offset = dissect_per_object_identifier(
+        tvb,
+        offset,
+        actx,
+        tree,
+        hf_index,
+        NULL);
+
+#.END
+
+
+#.FN_BODY Authentication-value/other/other-mechanism-value
+
+    offset=call_ber_oid_callback(
+        object_identifier_id,
+        tvb,
+        offset,
+        actx->pinfo,
+        tree, NULL);
+
+#.END
+
+#.FN_BODY AE-qualifier-form2
+    packet_info * pinfo = actx->pinfo;
+    atn_conversation_t *atn_cv = NULL;
+    guint32 ae_qualifier = 0;
+
+    /* dissect  ae-qualifier */
+    offset = dissect_per_integer(
+        tvb,
+        offset,
+        actx,
+        tree,
+        hf_index,
+        &ae_qualifier);
+
+
+    /*note: */
+    /* the field "calling-AE-qualifier" is optional, */
+    /* which means that we can exploit it only if it is present. */
+    /* We still depend on heuristical decoding of CM, CPDLC PDU's otherwise. */
+
+    /* AARQ/DT: dstref present, srcref is always zero */
+    if((pinfo->clnp_dstref) && (!pinfo->clnp_srcref)){
+        atn_cv = find_atn_conversation(&pinfo->dst,
+            pinfo->clnp_dstref,
+            &pinfo->src );
+    }
+
+    /* AARQ/CR: srcref present, dstref is always zero */
+    if((!pinfo->clnp_dstref) && (pinfo->clnp_srcref)){
+        atn_cv = find_atn_conversation(&pinfo->src,
+            pinfo->clnp_srcref,
+            &pinfo->dst );
+  }
+
+  if(atn_cv){
+      atn_cv->ae_qualifier = ae_qualifier;
+  }
+#.END
+
+#.FN_BODY AARQ-apdu
+    packet_info * pinfo = actx->pinfo;
+    aarq_data_t *aarq_data = NULL;
+    atn_conversation_t *atn_cv = NULL;
+    guint32 aircraft_24_bit_address = 0;
+
+    /* AARQ/DT: dstref present, srcref is always zero */
+    if((pinfo->clnp_dstref) && (!pinfo->clnp_srcref)){
+
+        atn_cv = find_atn_conversation(
+            &pinfo->dst,
+            pinfo->clnp_dstref,
+            &pinfo->src );
+        if(!atn_cv){
+            atn_cv = wmem_new(wmem_file_scope(), atn_conversation_t);
+            atn_cv->ae_qualifier = unknown;
+            create_atn_conversation(&pinfo->dst,
+                pinfo->clnp_dstref,
+                &pinfo->src ,
+                atn_cv);
+        }
+    }
+
+  /* AARQ/CR: srcref present, dstref is always zero */
+    if((!pinfo->clnp_dstref) && (pinfo->clnp_srcref)){
+        atn_cv = find_atn_conversation(&pinfo->src,
+            pinfo->clnp_srcref,
+            &pinfo->dst );
+        if(!atn_cv){
+            atn_cv = wmem_new(wmem_file_scope(), atn_conversation_t);
+            atn_cv->ae_qualifier = unknown;
+            create_atn_conversation(&pinfo->src,
+                pinfo->clnp_srcref,
+                &pinfo->dst ,
+                atn_cv);
+        }
+    }
+
+    /* conversation is to be created prior to decoding */
+    /* of "AE-qualifier-form2" which takes place here: */
+    %(DEFAULT_BODY)s
+
+
+    /* save AARQ packet data to create a conversation  */
+    /* when decoding the following AARE PDU */
+    /* ATN applications CM and CPDLC are air/ground applications */
+    /* so there is always an aircraft (with its 24-bit address) */
+    /* and a ground facility. */
+    /* the assumption is that there is only one open AARQ/AARE */
+    /* dialog per aircraft at a time. */
+    /* the aircraft's 24-bit address is used as a key to each AARQ */
+    /* data. AARQ data is used to create a conversation with */
+    /* air and ground endpoints (based on NSAP's and transport references) */
+    /* when decoding AARE.*/
+    /* note: */
+    /* it may be more robust to create the conversation */
+    /* in the "ositp" dissector an to merely use the conversation here */
+    aircraft_24_bit_address =
+        get_aircraft_24_bit_address_from_nsap(pinfo);
+
+    /* search for aarq entry */
+    aarq_data = (aarq_data_t *) wmem_tree_lookup32(
+        aarq_data_tree,
+        aircraft_24_bit_address);
+
+    if(!aarq_data){  /* aarq data not found, create new record */
+
+        /* alloc aarq data */
+        aarq_data = wmem_new(wmem_file_scope(), aarq_data_t);
+        aarq_data-> aarq_pending = FALSE;
+
+        /* insert aarq data */
+        wmem_tree_insert32(aarq_data_tree ,aircraft_24_bit_address,(void*)aarq_data);
+    }
+
+    /* check for pending AARQ/AARE sequences */
+    /* if "aarq_data-> aarq_pending" is set this means that there is already one  */
+    /* AARQ/AARE sequence pending (is unwise to overwrite AARE/AARQ) */
+    if (aarq_data-> aarq_pending == FALSE ) {
+
+      /* init aarq data */
+      memset(aarq_data,0,sizeof(aarq_data_t));
+
+      aarq_data->cv = atn_cv;
+      aarq_data-> aarq_pending = TRUE;
+    }
+
+#.END
+
+
+#.FN_BODY AARE-apdu
+  packet_info * pinfo = actx->pinfo;
+  guint32 aircraft_24_bit_address = 0 ;
+  atn_conversation_t *atn_cv = NULL;
+  aarq_data_t *aarq_data = NULL;
+
+  /* get AARQ data and use it to create a new conversation, */
+  /* the conversation is used along with  */
+  /* AARQ's "calling ae qualifier" to determine the */
+  /* type of air/ground application of each subsequent frame.*/
+  /* we use this information to invoke the correct application dissector. */
+  /* note: */
+  /* heuristical decoding of ASN1 will not work for all cases, */
+  /* for there may be CM PDU's which will exactly look like CPDLC PDU'S */
+
+  /* get 24-bit icao address */
+  aircraft_24_bit_address = get_aircraft_24_bit_address_from_nsap(pinfo);
+
+  /* search for aarq entry */
+  aarq_data = (aarq_data_t *) wmem_tree_lookup32(
+      aarq_data_tree,
+      aircraft_24_bit_address);
+
+  /* no aarq data present, do nothing  */
+  /* without both ends of the conversation and without */
+  /* the "calling ae-qualifier there is no point in setting up "*/
+  /* a conversation */
+  if(!aarq_data) {
+
+    return offset;
+  }
+
+  /* AARE/DT: dstref present, srcref is always zero */
+  if((pinfo->clnp_dstref) && (!pinfo->clnp_srcref)){
+
+    atn_cv = find_atn_conversation(&pinfo->dst,
+                          pinfo->clnp_dstref,
+                          &pinfo->src );
+
+    if(!atn_cv){ /* conversation not fond */
+
+      /* DT has only dstref - create new conversation */
+      create_atn_conversation(&pinfo->dst,
+                              pinfo->clnp_dstref,
+                              &pinfo->src ,
+                              aarq_data->cv);
+    }
+  }
+
+  /* AARE/CC: srcref and dstref present  */
+  if((pinfo->clnp_dstref) && (pinfo->clnp_srcref)){
+
+    atn_cv = find_atn_conversation(
+        &pinfo->src,
+        pinfo->clnp_srcref,
+        &pinfo->dst);
+
+    if(atn_cv){ /* conversation found. */
+
+      /* create new conversation for dstref */
+      create_atn_conversation(&pinfo->dst,
+                              pinfo->clnp_dstref,
+                              &pinfo->src ,
+                              aarq_data->cv);
+
+    }else { /* no conversation found  */
+      /* as CC contains srcref *and* dstref we use both to create new records  */
+      create_atn_conversation(&pinfo->src,
+                              pinfo->clnp_srcref,
+                              &pinfo->dst ,
+                              aarq_data->cv);
+      create_atn_conversation(&pinfo->dst,
+                              pinfo->clnp_dstref,
+                              &pinfo->src ,
+                              aarq_data->cv);
+    }
+  }
+
+  /* clear aarq data */
+  memset(aarq_data,0,sizeof(aarq_data_t));
+  aarq_data-> aarq_pending  =  FALSE;
+
+  %(DEFAULT_BODY)s
+
+
+#.END
+
+
+#.FN_BODY Associate-result
+ /* extension present: last param set to true. asn2wrs didn't take notice of that */
+ offset = dissect_per_constrained_integer(tvb, offset, actx, tree, hf_index,
+                                                            0U, 2U, NULL, TRUE);
+#.END
+
+#.FN_BODY Release-request-reason
+ /* extension present: last param set to true. asn2wrs didn't take notice of that */
+ offset = dissect_per_constrained_integer(tvb, offset, actx, tree, hf_index,
+                                                            0U, 30U, NULL, TRUE);
+#.END
+
+#.FN_BODY Release-response-reason
+
+ /* extension present: last param set to true. asn2wrs didn't take notice of that */
+ offset = dissect_per_constrained_integer(
+    tvb,
+    offset,
+    actx,
+    tree,
+    hf_index,
+    0U,
+    30U,
+    NULL,
+    TRUE);
+
+#.END
+
+#.FN_BODY Mechanism-name
+
+  offset = dissect_per_object_identifier(
+      tvb,
+      offset,
+      actx,
+      tree,
+      hf_index,
+      NULL);
+
+#.END
+
+#.FN_BODY RDNSequence
+
+  /*
+   * atn-ulcs.asn currently defines
+   *
+   * RDNSequence  ::= SEQUENCE OF RelativeDistinguishedName
+   * RelativeDistinguishedName ::= SET SIZE (1 .. MAX) OF AttributeTypeAndValue
+   * AttributeTypeAndValue ::= SEQUENCE { null NULL}
+   *
+   * which makes it easy to spam the dissection tree with null items. Dissect
+   * the first item only.
+   */
+  offset = dissect_per_constrained_sequence_of(tvb, offset, actx, tree, hf_index,
+                                      ett_atn_ulcs_RDNSequence, RDNSequence_sequence_of,
+                                      1, 1, FALSE);
+
+#.END
+
+#.FN_BODY RelativeDistinguishedName
+
+  /*
+   * Dissect the first null item only, similar to RDNSequence.
+   */
+  offset = dissect_per_constrained_set_of(tvb, offset, actx, tree, hf_index,
+                                             ett_atn_ulcs_RelativeDistinguishedName, RelativeDistinguishedName_set_of,
+                                             1, 1, FALSE);
+
+#.END
+
+#.FN_BODY EXTERNALt/data-value-descriptor
+
+  offset = dissect_per_octet_string(
+      tvb,
+      offset,
+      actx,
+      tree,
+      hf_index,
+      -1,
+      -1,
+      FALSE,
+      &actx->external.data_value_descriptor);
+  actx->external.data_value_descr_present = TRUE;
+
+#.END
+
+#.FN_BODY EXTERNALt/encoding/single-ASN1-type
+
+  %(DEFAULT_BODY)s
+
+#.END
+
+#.FN_BODY EXTERNALt/encoding/octet-aligned
+
+  %(DEFAULT_BODY)s
+
+#.END
+
+#.FN_BODY EXTERNALt/encoding/arbitrary
+  tvbuff_t *tvb_usr = NULL;
+  packet_info * pinfo = actx->pinfo;
+  atn_conversation_t *atn_cv = NULL;
+  heur_dtbl_entry_t *hdtbl_entry;
+
+  /* decode bit-string user data within ACSE  */
+  offset = dissect_per_bit_string(
+    tvb,
+    offset,
+    actx,
+    tree, hf_index,
+    NO_BOUND,
+    NO_BOUND,
+    FALSE,
+    NULL,
+    0,
+    &tvb_usr,
+    NULL);
+
+  if (tvb_usr) {
+    /* DT: dstref present, srcref is always zero */
+    if((pinfo->clnp_dstref) && (!pinfo->clnp_srcref)){
+
+      atn_cv = find_atn_conversation(
+          &pinfo->dst,
+          pinfo->clnp_dstref,
+          &pinfo->src);
+    }
+    /* CR: srcref present, dstref always zero */
+    if((pinfo->clnp_srcref) && (!pinfo->clnp_dstref)){
+
+      atn_cv = find_atn_conversation(
+          &pinfo->src,
+          pinfo->clnp_srcref,
+          &pinfo->dst);
+    }
+    /* CC: srcref and dstref present */
+    if((pinfo->clnp_srcref) && (pinfo->clnp_dstref)){
+
+      atn_cv = find_atn_conversation(
+          &pinfo->src,
+          pinfo->clnp_srcref,
+          &pinfo->dst);
+    }
+
+    if(atn_cv) {
+        switch(atn_cv->ae_qualifier){
+          case cma: /* contact management */
+
+              call_dissector_with_data(
+                    atn_cm_handle,
+                    tvb_new_subset_remaining(tvb_usr, 0),
+                    pinfo,
+                    root_tree,
+                    NULL);
+              break;
+          case cpdlc: /* plain old cpdlc */
+          case pmcpdlc: /* protected mode cpdlc */
+
+              call_dissector_with_data(
+                    atn_cpdlc_handle,
+                    tvb_new_subset_remaining(tvb_usr, 0),
+                    pinfo,
+                    root_tree,
+                    NULL);
+              break;
+          default: /* unknown or unhandled datalink application */
+
+              dissector_try_heuristic(
+                  atn_ulcs_heur_subdissector_list,
+                  tvb_new_subset_remaining(tvb_usr,0),
+                  actx->pinfo,
+                  root_tree,
+                  &hdtbl_entry,
+                  NULL);
+                break;
+          }
+    }else {
+
+      dissector_try_heuristic(
+              atn_ulcs_heur_subdissector_list,
+              tvb_new_subset_remaining(tvb_usr,0),
+              actx->pinfo,
+              root_tree,
+              &hdtbl_entry,
+              NULL);
+    }
+  }
+
+  offset += tvb_reported_length_remaining(tvb, offset);
+
+#.END
+
+#
+# Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+#
+# Local variables:
+# c-basic-offset: 4
+# tab-width: 8
+# indent-tabs-mode: nil
+# End:
+#
+# vi: set shiftwidth=4 tabstop=8 expandtab:
+# :indentSize=4:tabSize=8:noTabs=true:
+#
diff --git a/epan/dissectors/asn1/atn-ulcs/packet-atn-ulcs-template.c b/epan/dissectors/asn1/atn-ulcs/packet-atn-ulcs-template.c
new file mode 100644
index 00000000..18e32836
--- /dev/null
+++ b/epan/dissectors/asn1/atn-ulcs/packet-atn-ulcs-template.c
@@ -0,0 +1,891 @@
+/* packet-atn-ulcs.c
+ * By Mathias Guettler <guettler@web.de>
+ * Copyright 2013
+ *
+ * Routines for ATN upper layer
+ * protocol packet disassembly
+
+ * ATN upper layers are embedded within OSI Layer 4 (COTP).
+ *
+ * ATN upper layers contain:
+ * Session Layer (NUL protocol option)
+ * Presentation Layer (NUL protocol option)
+ * ATN upper Layer/Application (ACSE PDU or PDV-list PDU)
+
+ * ATN applications protocols (i.e. CM or CPDLC) are contained within
+ * ACSE user-information or PDV presentation data.
+
+ * details see:
+ * http://en.wikipedia.org/wiki/CPDLC
+ * http://members.optusnet.com.au/~cjr/introduction.htm
+
+ * standards:
+ * http://legacy.icao.int/anb/panels/acp/repository.cfm
+
+ * note:
+ * We are dealing with ATN/ULCS aka ICAO Doc 9705 Ed2 here
+ * (don't think there is an ULCS equivalent for "FANS-1/A ").
+
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+/*
+ developer comments:
+why not using existing ses, pres and acse dissectors ?
+    ATN upper layers are derived from OSI standards for session,
+    presentation and application but the encoding differs
+    (it's PER instead of BER encoding to save bandwith).
+    Session and presentation use the "null" encoding option,
+    meaning that they are only present at connection establishment
+    and ommitted otherwise.
+    Instead of adapting existing dissectors it seemed simpler and cleaner
+    to implement everything the new atn-ulcs dissector.
+
+why using conversations ?
+    PER encoded user data is ambigous; the same encoding may apply to a CM or
+    CPDLC PDU. The workaround is to decode on a transport connection basis.
+    I use my own version of conversations to identify
+    the transport connection the PDU belongs to for the standard functions
+    from "conversation.h" didn't work out.
+
+what is the use of AARQ/AARE data ?
+    Converstions should be maintained on the COTP layer in a standard way
+    for there are usually more packets available than in the layers above.
+    In the worst case my dissector is called from a DT packet which
+    has destination references but no source reference.
+    I have to guess the reference used the other way round
+    (curently I am using ACSE PDU'S used during OSI connection establishment for that).
+    The idea is that each ACSE AARQ is answered by ACSE AARE and having this sequence
+    I have all the source/destination references for this transport connection.
+    I use AARQ/AARE data to store the source/destination reference of AARQ as well
+    as the optional ae-qualifier which tells me the application and
+    the dissector I have to use.
+    This approach donesn't work well when there are interleaving AARQ/AARE sequences for
+    the same aircraft.
+
+which ATN standard is supported ?
+    The dissector has been tested with ICAO doc9705 Edition2 compliant traffic.
+    No ATN Secutity is supported.
+    note:
+    The ATN upper layers are derived from OSI standards (ICAO DOC 9705)
+    while ATN/IPS (ICAO DOC 9896) which is entirely based on IPV6.
+
+*/
+
+/*
+ known defects/deficiencies:
+
+- user-information within AARE is sometines not decoded due to an unset flag
+    (the field is optional). As far as I can tell asn2wrs is right here,
+    but on the other hand I know that in all of this cases user-information
+    is present and is processed by the ATN end system.
+    Maybe a true ATN expert may help me out here.
+
+  - The conversation handling is based on src/dst addresses as well as
+    source or destination references depending on the TP4 packet type.
+    This means that after some time these references get reused for
+    new conversations. This almost certain happens for traces longer
+    than one day rendering this dissector unsuitable for captures exceeding
+    this one day.
+
+*/
+
+#include "config.h"
+
+#ifndef _MSC_VER
+#include <stdint.h>
+#endif
+
+
+#include <epan/packet.h>
+#include <epan/address.h>
+#include <epan/conversation.h>
+#include <epan/osi-utils.h>
+#include "packet-ber.h"
+#include "packet-per.h"
+#include "packet-atn-ulcs.h"
+
+#define ATN_ACSE_PROTO "ICAO Doc9705 ULCS ACSE (ISO 8649/8650-1:1996)"
+#define ATN_ULCS_PROTO "ICAO Doc9705 ULCS"
+
+void proto_register_atn_ulcs(void);
+void proto_reg_handoff_atn_ulcs(void);
+
+static heur_dissector_list_t atn_ulcs_heur_subdissector_list;
+
+/* presentation subdissectors i.e. CM, CPDLC */
+static dissector_handle_t atn_cm_handle = NULL;
+static dissector_handle_t atn_cpdlc_handle = NULL;
+
+static int proto_atn_ulcs          = -1;
+static guint32 ulcs_context_value = 0;
+static const char *object_identifier_id;
+
+static wmem_tree_t *aarq_data_tree = NULL;
+static wmem_tree_t *atn_conversation_tree = NULL;
+
+
+static proto_tree *root_tree = NULL;
+
+/* forward declarations for functions generated from asn1 */
+static int dissect_atn_ulcs_T_externalt_encoding_single_asn1_type(
+    tvbuff_t *tvb _U_,
+    int offset _U_,
+    asn1_ctx_t *actx _U_,
+    proto_tree *tree _U_,
+    int hf_index
+    _U_);
+
+static int dissect_atn_ulcs_T_externalt_encoding_octet_aligned(
+    tvbuff_t *tvb _U_,
+    int offset _U_,
+    asn1_ctx_t *actx _U_,
+    proto_tree *tree _U_,
+    int hf_index _U_);
+
+static int dissect_atn_ulcs_T_externalt_encoding_arbitrary(
+    tvbuff_t *tvb _U_,
+    int offset _U_,
+    asn1_ctx_t *actx _U_,
+    proto_tree *tree _U_,
+    int hf_index _U_);
+
+static int dissect_ACSE_apdu_PDU(
+    tvbuff_t *tvb _U_,
+    packet_info *pinfo _U_,
+    proto_tree *tree _U_,
+    void *data _U_);
+
+guint32 dissect_per_object_descriptor_t(
+    tvbuff_t *tvb,
+    guint32 offset,
+    asn1_ctx_t *actx,
+    proto_tree *tree,
+    int hf_index,
+    tvbuff_t **value_tvb);
+
+static gint dissect_atn_ulcs(
+    tvbuff_t *tvb,
+    packet_info *pinfo,
+    proto_tree  *tree,
+    void *data _U_);
+
+#include "packet-atn-ulcs-hf.c"
+
+#include "packet-atn-ulcs-ett.c"
+static gint ett_atn_ulcs = -1;
+static gint ett_atn_acse = -1;
+
+#include "packet-atn-ulcs-fn.c"
+
+#if 0
+/* re-implementing external data: packet-per.c */
+static const value_string per_External_encoding_vals[] = {
+{   0, "single-ASN1-type" },
+{   1, "octet-aligned" },
+{   2, "arbitrary" },
+{ 0, NULL }
+};
+
+/* re-implementing external data: packet-per.c */
+static const per_choice_t External_encoding_choice[] =
+{
+    {   0,
+        &hf_atn_ulcs_externalt_encoding_single_asn1_type,
+        ASN1_NO_EXTENSIONS,
+        dissect_atn_ulcs_T_externalt_encoding_single_asn1_type
+    },
+    {   1,
+        &hf_atn_ulcs_externalt_encoding_octet_aligned,
+        ASN1_NO_EXTENSIONS,
+        dissect_atn_ulcs_T_externalt_encoding_octet_aligned
+    },
+    {   2,
+        &hf_atn_ulcs_externalt_encoding_arbitrary,
+        ASN1_NO_EXTENSIONS,
+        dissect_atn_ulcs_T_externalt_encoding_arbitrary
+    },
+    {   0,
+        NULL,
+        0,
+        NULL
+    }
+};
+#endif
+
+/* ATN Session layer */
+#define SES_PDU_TYPE_MASK     0xf8
+#define SES_PARAM_IND_MASK    0x04
+#define SES_PARAM_B2_MASK     0x02
+#define SES_PARAM_B1_MASK     0x01
+
+static int hf_atn_ses_type = -1;
+static int hf_atn_ses_param_ind = -1;
+static int hf_atn_ses_param_b1 = -1;
+static int hf_atn_ses_param_b2 = -1;
+
+static gint ett_atn_ses = -1;
+
+#define ATN_SES_PROTO "ICAO Doc9705 ULCS Session (ISO 8326/8327-1:1994)"
+
+const value_string atn_ses_param_ind[] =
+{
+    {0, "No Parameter Indication "},
+    {1, "Parameter Indication "},
+    {0, NULL }
+};
+
+const value_string srf_b2[] =
+{
+    {0, "Transport Connection is kept"},
+    {1, "Transport Connection is released" },
+    {0, NULL }
+};
+
+const value_string srf_b1[] =
+{
+    {0, "Transport Connection is transient"},
+    {1, "Transport Connection is persistent"},
+    {0, NULL }
+};
+
+#define SES_ATN_SCN       0xe8
+#define SES_ATN_SCNC      0xf8
+#define SES_ATN_SAC       0xf0
+#define SES_ATN_SACC      0xd8
+#define SES_ATN_SRF       0xe0
+#define SES_ATN_SRFC      0xa0
+
+const value_string atn_ses_type[] =
+{
+    { 0x1d, "Short Connect (SCN) SPDU" },
+    { 0x1f, "Short Connect Accept (SAC) SPDU" },
+    { 0x1e, "Short Connect Accept Continue (SACC) SPDU" },
+    { 0x1c, "Short Refuse (SRF) SPDU" },
+    { 0x14, "Short Refuse Continue (SRFC) SPDU" },
+    {0, NULL }
+};
+
+/* ATN Presentation layer */
+#define ATN_PRES_PROTO "ICAO Doc9705 ULCS Presentation (ISO 8822/8823-1:1994)"
+
+static int hf_atn_pres_err   = -1;
+static int hf_atn_pres_pdu_type = -1;
+static gint ett_atn_pres    = -1;
+
+#define ATN_SES_PRES_MASK 0xf803
+#define PRES_CPR_ER_MASK    0x70
+
+/* type determined by SPDU and PPDU */
+const value_string atn_pres_vals[] =
+{
+    { 0xe802, "Short Presentation Connect PPDU (CP) " },
+    { 0xf802, "Short Presentation Connect PPDU (CP) " },
+    { 0xf002, "Short Presentation Connect Accept PPDU (CPA)" },
+    { 0xd802, "Short Presentation Connect Accept PPDU (CPA)" },
+    { 0xe002, "Short Presentation Connect Reject PPDU (CPR)" },
+    { 0xa002, "Short Presentation Connect Reject PPDU (CPR)" },
+    {0,         NULL }
+};
+
+/* Short Presentation Connect Reject PPDU's 0yyy 00zz */
+const value_string atn_pres_err[] =
+{
+    { 0x00, "Presentation-user" },
+    { 0x01, "Reason not specified (transient)"},
+    { 0x02, "Temporary congestion (transient)"},
+    { 0x03, "Local limit exceeded (transient)"},
+    { 0x04, "Called presentation-address unknown (permanent)"},
+    { 0x05, "Protocol version not supported (permanent)"},
+    { 0x06, "Default context not supported (permanent)"},
+    { 0x07, "User data not readable (permanent)"},
+    { 0,          NULL }
+};
+
+#if 0
+/* re-implementing external data: packet-per.c */
+static int  atn_ulcs_Externalt_encoding(
+    tvbuff_t *tvb _U_,
+    int offset _U_,
+    asn1_ctx_t *actx _U_,
+    proto_tree *tree _U_,
+    int hf_index _U_)
+{
+    offset = dissect_per_choice(
+        tvb,
+        offset,
+        actx,
+        tree,
+        hf_index,
+        ett_atn_ulcs_EXTERNALt,
+        External_encoding_choice,
+        &actx->external.encoding);
+
+    return offset;
+}
+
+/* re-implementing external data: packet-per.c */
+static guint32  atn_per_external_type(
+    tvbuff_t *tvb _U_,
+    guint32 offset,
+    asn1_ctx_t *actx,
+    proto_tree *tree _U_,
+    int hf_index _U_,
+    per_type_fn type_cb)
+{
+    memset(&actx->external, '\0', sizeof(actx->external));
+    actx->external.hf_index = -1;
+    actx->external.encoding = -1;
+
+    actx->external.u.per.type_cb = type_cb;
+    offset = atn_ulcs_Externalt_encoding(
+        tvb,
+        offset,
+        actx,
+        tree,
+        hf_index);
+
+    memset(
+        &actx->external,
+        '\0',
+        sizeof(actx->external));
+
+    actx->external.hf_index = -1;
+    actx->external.encoding = -1;
+
+    return offset;
+}
+#endif
+
+/* determine 24-bit aircraft address(ARS) */
+/* from 20-byte ATN NSAP. */
+guint32 get_aircraft_24_bit_address_from_nsap(
+    packet_info *pinfo)
+{
+    const guint8* addr = NULL;
+    guint32 ars =0;
+    guint32 adr_prefix =0;
+
+    /* check NSAP address type*/
+    if( (pinfo->src.type != get_osi_address_type()) ||
+        (pinfo->dst.type != get_osi_address_type())) {
+        return ars; }
+
+    /* 20 octets address length required */
+    /* for ATN */
+    if( (pinfo->src.len != 20) ||
+        (pinfo->dst.len != 20)) {
+        return ars; }
+
+    /* first try source address */
+    /* if the src address originates */
+    /* from an aircraft it's downlink */
+
+    /* convert addr into 32-bit integer */
+    addr = (const guint8 *)pinfo->src.data;
+    adr_prefix =
+        ((addr[0]<<24) |
+        (addr[1]<<16) |
+        (addr[2]<<8) |
+        addr[3] );
+
+    /* according to ICAO doc9507 Ed2 SV5  */
+    /* clause 5.4.3.8.1.5 and  5.4.3.8.1.3 */
+    /* mobile addresses contain "c1" of "41" */
+    /* in the VER subfield of the NSAP */
+    if((adr_prefix == 0x470027c1) ||
+        (adr_prefix == 0x47002741)) {
+      /* ICAO doc9507 Ed2 SV5 5.4.3.8.4.4 */
+      /* states that the ARS subfield containes */
+      /* the  24-bitaddress of the aircraft */
+        ars = ((addr[8])<<16) |
+            ((addr[9])<<8) |
+            (addr[10]);
+    }
+
+    /* try destination address */
+    /* if the src address originates */
+    /* from an aircraft it's downlink */
+
+    /* convert addr into 32-bit integer */
+    addr = (const guint8 *)pinfo->dst.data;
+    adr_prefix = ((addr[0]<<24) |
+        (addr[1]<<16) |
+        (addr[2]<<8) |
+        addr[3] );
+
+    /* according to ICAO doc9507 Ed2 SV5  */
+    /* clause 5.4.3.8.1.5 and  5.4.3.8.1.3 */
+    /* mobile addresses contain "c1" of "41" */
+    /* in the VER subfield of the NSAP */
+    if((adr_prefix == 0x470027c1) ||
+        (adr_prefix == 0x47002741)) {
+      /* ICAO doc9507 Ed2 SV5 5.4.3.8.4.4 */
+      /* states that the ARS subfield containes */
+      /* the  24-bitaddress of the aircraft */
+      ars = ((addr[8])<<16) |
+            ((addr[9])<<8) |
+            (addr[10]);
+    }
+    return ars;
+}
+
+/* determine whether a PDU is uplink or downlink */
+/* by checking for known aircraft  address prefices*/
+int check_heur_msg_type(packet_info *pinfo  _U_)
+{
+    int t = no_msg;
+    const guint8* addr = NULL;
+    guint32 adr_prefix =0;
+
+    /* check NSAP address type*/
+    if( (pinfo->src.type != get_osi_address_type()) || (pinfo->dst.type != get_osi_address_type())) {
+        return t; }
+
+    /* check NSAP address length; 20 octets address length required */
+    if( (pinfo->src.len != 20) || (pinfo->dst.len != 20)) {
+        return t; }
+
+    addr = (const guint8 *)pinfo->src.data;
+
+    /* convert address to 32-bit integer  */
+    adr_prefix = ((addr[0]<<24) | (addr[1]<<16) | (addr[2]<<8) | addr[3] );
+
+    /* According to the published ATN NSAP adddressing scheme */
+    /* in ICAO doc9705 Ed2 SV5 5.4.3.8.1.3 and 5.4.3.8.1.5  */
+    /* the "VER" field shall be 0x41 ("all Mobile AINSC") or */
+    /* 0xc1 ("all Mobile ATSC") for mobile stations (aka aircraft).*/
+    if((adr_prefix == 0x470027c1) || (adr_prefix == 0x47002741)) {
+        t = dm; /* source is an aircraft: it's a downlink PDU */
+    }
+
+    addr = (const guint8 *)pinfo->dst.data;
+
+    /* convert address to 32-bit integer  */
+    adr_prefix = ((addr[0]<<24) | (addr[1]<<16) | (addr[2]<<8) | addr[3] );
+
+    /* According to the published ATN NSAP adddressing scheme */
+    /* in ICAO doc9705 Ed2 SV5 5.4.3.8.1.3 and 5.4.3.8.1.5  */
+    /* the "VER" field shall be 0x41 ("all Mobile AINSC") or */
+    /* 0xc1 ("all Mobile ATSC") for mobile stations (aka aircraft).*/
+    if((adr_prefix == 0x470027c1) || (adr_prefix == 0x47002741)) {
+        t = um; /* destination is aircraft: uplink PDU */
+    }
+
+    return t;
+}
+
+/* conversation may be used by other dissectors  */
+wmem_tree_t *get_atn_conversation_tree(void){
+    return atn_conversation_tree;
+}
+
+
+/* find a atn conversation tree node by an endpoint  */
+/* an endpoint is identified by atn src and dst addresses */
+/* and srcref or dstref (depends on the transport packet type) */
+/* IMHO it's a hack - conversations should be maintained */
+/* at transport layer (cotp) but this isn't working yet. */
+atn_conversation_t * find_atn_conversation(
+    address *address1,
+    guint16 clnp_ref1,
+    address *address2 )
+{
+    atn_conversation_t *cv = NULL;
+    guint32 key = 0;
+    guint32 tmp = 0;
+
+    tmp = add_address_to_hash( tmp, address1);
+    key = (tmp << 16) | clnp_ref1 ;
+
+    tmp = add_address_to_hash( tmp, address2);
+    key = (tmp << 24) | key ;
+
+    /* search for atn conversation */
+    cv = (atn_conversation_t *)
+        wmem_tree_lookup32(get_atn_conversation_tree(),key);
+
+    return cv;
+}
+
+/* create a atn conversation tree node  */
+/* conversation data is to be allocated externally */
+/* a conversation may be referenced from both endpoints */
+atn_conversation_t * create_atn_conversation(
+    address *address1,
+    guint16 clnp_ref1,
+    address *address2,
+    atn_conversation_t *conversation)
+{
+    atn_conversation_t *cv = NULL;
+    guint32 key = 0;
+    guint32 tmp = 0;
+
+    tmp = add_address_to_hash( tmp, address1);
+    key = (tmp << 16) | clnp_ref1 ;
+
+    tmp = add_address_to_hash( tmp, address2);
+    key = (tmp << 24) | key ;
+
+    /* search for aircraft entry */
+    cv = (atn_conversation_t *)
+    wmem_tree_lookup32(
+        get_atn_conversation_tree(),
+        key);
+
+    /* tree node  already present  */
+    if(cv) {
+      return NULL; }
+
+    /* insert conversation data in tree*/
+    wmem_tree_insert32(
+        get_atn_conversation_tree(),
+        key,
+        (void*)conversation);
+
+    return conversation;
+}
+
+static int
+dissect_atn_ulcs(
+    tvbuff_t *tvb,
+    packet_info *pinfo,
+    proto_tree *tree,
+    void *data _U_)
+{
+    int offset = 0;
+    proto_item *ti = NULL;
+    proto_tree *atn_ulcs_tree = NULL;
+    guint8 value_pres = 0;
+    guint8 value_ses = 0;
+    guint16 value_ses_pres = 0;
+
+    root_tree = tree;
+
+    /* data pointer */
+    /* decode as PDV-list */
+    if ( (int)(intptr_t)  data == FALSE )
+    {
+        ti = proto_tree_add_item(
+            tree,
+            proto_atn_ulcs,
+            tvb,
+            0,
+            0 ,
+            ENC_NA);
+
+        atn_ulcs_tree = proto_item_add_subtree(
+            ti,
+            ett_atn_ulcs);
+
+        dissect_Fully_encoded_data_PDU(
+            tvb,
+            pinfo,
+            atn_ulcs_tree, NULL);
+
+        return offset +
+          tvb_reported_length_remaining(tvb, offset ) ;
+    }
+
+    /* decode as SPDU, PPDU and ACSE PDU */
+    if ( (int)(intptr_t)  data == TRUE )
+    {
+        /* get session and presentation PDU's */
+        value_ses_pres = tvb_get_ntohs(tvb, offset);
+
+        /* SPDU: dissect session layer */
+        atn_ulcs_tree = proto_tree_add_subtree(
+            tree, tvb, offset, 0,
+            ett_atn_ses, NULL, ATN_SES_PROTO );
+
+        /* get SPDU (1 octet) */
+        value_ses = tvb_get_guint8(tvb, offset);
+
+        /* SPDU type/identifier  */
+        proto_tree_add_item(atn_ulcs_tree,
+            hf_atn_ses_type,
+            tvb,
+            offset,
+            1,
+            ENC_BIG_ENDIAN );
+
+        /* SPDU parameters may be present in Short Refuse */
+        /* or Short Refuse Continue SPDU's */
+        switch(value_ses & SES_PDU_TYPE_MASK){
+            case SES_ATN_SRF:
+            case SES_ATN_SRFC:
+
+                /* SPDU parameter presence */
+                proto_tree_add_item(atn_ulcs_tree,
+                    hf_atn_ses_param_ind,
+                    tvb,
+                    offset,
+                    1,
+                    ENC_BIG_ENDIAN );
+
+                /* parameter B2 */
+                proto_tree_add_item(atn_ulcs_tree,
+                    hf_atn_ses_param_b2,
+                    tvb,
+                    offset,
+                    1,
+                    ENC_BIG_ENDIAN );
+
+                /* parameter B1 */
+                proto_tree_add_item(atn_ulcs_tree,
+                    hf_atn_ses_param_b1,
+                    tvb,
+                    offset,
+                    1,
+                    ENC_BIG_ENDIAN );
+
+              break;
+            default:
+              break;
+        }
+        offset++;
+
+        /* PPDU: dissect presentation layer */
+        atn_ulcs_tree = proto_tree_add_subtree(
+            tree, tvb, offset, 0,
+            ett_atn_pres, NULL, ATN_PRES_PROTO );
+
+        value_pres = tvb_get_guint8(tvb, offset);
+
+        /* need session context to identify PPDU type */
+        /* note: */
+        proto_tree_add_uint_format(atn_ulcs_tree, hf_atn_pres_pdu_type,
+            tvb,
+            offset,
+            1,
+            value_ses_pres,
+            "%s (0x%02x)",
+            val_to_str_const( value_ses_pres & ATN_SES_PRES_MASK, atn_pres_vals, "?"),
+            value_pres);
+
+        /* PPDU errorcode in case of SRF/CPR */
+        switch(value_ses & SES_PDU_TYPE_MASK){
+            case SES_ATN_SRF:
+            case SES_ATN_SRFC:
+                proto_tree_add_item(
+                    atn_ulcs_tree,
+                    hf_atn_pres_err,
+                    tvb,
+                    offset,
+                    1,
+                    ENC_BIG_ENDIAN );
+                break;
+            default:
+                break;
+        }
+
+        offset++;
+
+        /* ACSE PDU: dissect application layer */
+        atn_ulcs_tree = proto_tree_add_subtree(
+            tree, tvb, offset, 0,
+            ett_atn_acse, NULL, ATN_ACSE_PROTO );
+
+        dissect_ACSE_apdu_PDU(
+            tvb_new_subset_remaining(tvb, offset),
+            pinfo,
+            atn_ulcs_tree, NULL);
+
+        return offset +
+            tvb_reported_length_remaining(tvb, offset );
+    }
+    return offset;
+}
+
+static gboolean dissect_atn_ulcs_heur(
+    tvbuff_t *tvb,
+    packet_info *pinfo,
+    proto_tree *tree,
+    void *data _U_)
+{
+    /* do we have enough data*/
+    /* at least session + presentation data or pdv-list */
+    if (tvb_captured_length(tvb) < 2){
+        return FALSE; }
+
+    /* check for session/presentation/ACSE PDU's  */
+    /* SPDU and PPDU are one octet each */
+    switch( tvb_get_ntohs(tvb, 0) & 0xf8ff ){
+        case 0xe802: /* SCN + CP*/
+        case 0xf802: /* SCNC + CP */
+        case 0xf002: /* SAC + CPA */
+        case 0xd802: /* SACC + CPA */
+        case 0xe002: /* SRF + CPR + R0 */
+        case 0xe012: /* SRF + CPR + R1 */
+        case 0xe022: /* SRF + CPR + R2 */
+        case 0xe032: /* SRF + CPR + R3 */
+        case 0xe042: /* SRF + CPR + R4 */
+        case 0xe052: /* SRF + CPR + R5 */
+        case 0xe062: /* SRF + CPR + R6 */
+        case 0xe072: /* SRF + CPR + R7 */
+        case 0xa002: /* SRFC + CPR + R0*/
+        case 0xa012: /* SRFC + CPR + R1*/
+        case 0xa022: /* SRFC + CPR + R2*/
+        case 0xa032: /* SRFC + CPR + R3*/
+        case 0xa042: /* SRFC + CPR + R4*/
+        case 0xa052: /* SRFC + CPR + R5*/
+        case 0xa062: /* SRFC + CPR + R6*/
+        case 0xa072: /* SRFC + CPR + R7*/
+            /* indicate to dissector routine */
+            /* that a least SPDU, PPDU and */
+            /* ACSE PDU is present */
+            dissect_atn_ulcs(
+                tvb,
+                pinfo,
+                tree,
+                (void*) TRUE);
+            return TRUE;
+        default:  /* no SPDU */
+            break;
+    }
+
+    /* try to detect "Fully-encoded-data" heuristically */
+    /* the constants listed match the ASN.1 PER encoding */
+    /* of PDV-List */
+    switch(  tvb_get_ntohs(tvb, 0) & 0xfff0 ){
+        case 0x0020: /* acse-apdu */
+        case 0x00a0: /* user-ase-apdu */
+        /* indicate to dissector routine */
+        /* that a PDV-list PDU is present */
+        /*  */
+        /* PDV-list PDU may contain */
+        /* application protocol data (CM, CPDLC) */
+        /* or an ACSE PDU */
+            dissect_atn_ulcs(tvb, pinfo, tree, (void*) FALSE);
+            return TRUE;
+            break;
+        default:  /* no or unsupported PDU */
+            break;
+    }
+    return FALSE;
+}
+
+void proto_register_atn_ulcs (void)
+{
+    static hf_register_info hf_atn_ulcs[] = {
+        #include "packet-atn-ulcs-hfarr.c"
+        {&hf_atn_ses_type,
+        { "SPDU Type",
+          "atn-ulcs.ses.type",
+          FT_UINT8,
+          BASE_HEX,
+          VALS(atn_ses_type),
+          0xf8,
+          "Indicates presence of session parameters",
+          HFILL}},
+        {&hf_atn_ses_param_ind,
+        { "SPDU Parameter Indication",
+          "atn-ulcs.ses.parameter-indication",
+          FT_UINT8,
+          BASE_HEX,
+          VALS(atn_ses_param_ind),
+          SES_PARAM_IND_MASK,
+          "Indicates presence of session parameters",
+          HFILL}},
+      {&hf_atn_ses_param_b1,
+        { "SRF Parameter B1",
+          "atn-ulcs.ses.srf-b1",
+          FT_UINT8,
+          BASE_HEX,
+          VALS(srf_b1),
+          0x01,
+          "Determines if transport connection reject is transient or persistent",
+          HFILL}},
+      {&hf_atn_ses_param_b2,
+        { "SRF Parameter B2",
+          "atn-ulcs.ses.srf-b2",
+          FT_UINT8,
+          BASE_HEX,
+          VALS(srf_b2),
+          0x02,
+          "Determines if transport connection is retained or released",
+          HFILL}},
+      { &hf_atn_pres_err,
+        { "Error Code", "atn-ulcs.pres.cpr-error",
+          FT_UINT8,
+          BASE_HEX,
+          VALS(atn_pres_err),
+          PRES_CPR_ER_MASK,
+          NULL,
+          HFILL}},
+      { &hf_atn_pres_pdu_type,
+        { "PDU type", "atn-ulcs.pres.pdu_type",
+          FT_UINT16,
+          BASE_HEX,
+          NULL,
+          ATN_SES_PRES_MASK,
+          NULL,
+          HFILL}},
+    };
+
+    static gint *ett[] = {
+        #include "packet-atn-ulcs-ettarr.c"
+        &ett_atn_ses,
+        &ett_atn_pres,
+        &ett_atn_acse,
+        &ett_atn_ulcs
+    };
+
+    proto_atn_ulcs = proto_register_protocol (
+        ATN_ULCS_PROTO ,
+        "ATN-ULCS",
+        "atn-ulcs");
+
+    proto_register_field_array (
+        proto_atn_ulcs,
+        hf_atn_ulcs,
+        array_length(hf_atn_ulcs));
+
+    proto_register_subtree_array (
+        ett,
+        array_length (ett));
+
+    register_dissector(
+        "atn-ulcs",
+        dissect_atn_ulcs,
+        proto_atn_ulcs);
+
+    /* initiate sub dissector list */
+    atn_ulcs_heur_subdissector_list = register_heur_dissector_list("atn-ulcs", proto_atn_ulcs);
+
+    /* init aare/aare data */
+    aarq_data_tree = wmem_tree_new_autoreset(wmem_epan_scope(), wmem_file_scope());
+
+    atn_conversation_tree = wmem_tree_new_autoreset(wmem_epan_scope(), wmem_file_scope());
+}
+
+void proto_reg_handoff_atn_ulcs(void)
+{
+    atn_cm_handle = find_dissector_add_dependency("atn-cm", proto_atn_ulcs);
+    atn_cpdlc_handle = find_dissector_add_dependency("atn-cpdlc", proto_atn_ulcs);
+
+    /* add session dissector to cotp dissector list dissector list*/
+    heur_dissector_add(
+        "cotp",
+        dissect_atn_ulcs_heur,
+        "ATN-ULCS over COTP",
+        "atn-ucls_cotp",
+        proto_atn_ulcs, HEURISTIC_ENABLE);
+}
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 4
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=4 tabstop=8 expandtab:
+ * :indentSize=4:tabSize=8:noTabs=true:
+ */
diff --git a/epan/dissectors/asn1/atn-ulcs/packet-atn-ulcs-template.h b/epan/dissectors/asn1/atn-ulcs/packet-atn-ulcs-template.h
new file mode 100644
index 00000000..872403f8
--- /dev/null
+++ b/epan/dissectors/asn1/atn-ulcs/packet-atn-ulcs-template.h
@@ -0,0 +1,81 @@
+/* packet-atn-ulcs.h
+ * Definitions for atn packet disassembly structures and routines
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#ifndef PACKET_ATN_ULCS_H
+#define PACKET_ATN_ULCS_H
+
+#include "packet.h"
+
+#include <epan/wmem_scopes.h>
+
+enum msg_type {
+    um,
+    dm,
+    no_msg
+};
+
+enum ae_qualifier {
+    ads = 0,
+    cma =1, /* contact management (CM) */
+    cpdlc = 2, /* "plain old" CPDLC */
+    ati = 3 ,
+    arf =10 ,
+    met =11,
+    gac =12,
+    pmcpdlc =22,  /* "protected mode" CPDLC */
+    unknown = -1
+};
+
+typedef struct atn_conversation_t {
+    gint ae_qualifier; /* A/G application type  */
+} atn_conversation_t;
+
+atn_conversation_t * create_atn_conversation(
+    address*,
+    guint16,
+    address*,
+    atn_conversation_t*);
+
+atn_conversation_t * find_atn_conversation(
+    address*,
+    guint16,
+    address*);
+
+/* struct for conversation data reconstruction used in AARQ and AARE */
+/* if transport data is larger than 32 octets AARQ/AARE is contained */
+/* within DT frames which have only dest_ref, but no src_ref */
+/* if AARQ/AARQ is contained within CR/CC only src_ref is present in CR */
+/* while CC provides src_ref and dstref */
+typedef struct aarq_data_t {
+    gboolean aarq_pending; /* flag tells whether AARQ/sequence is pending (true)  */
+                           /* required not to mix up different AARQ/AARE sequences */
+                           /* during simoultanous establishment of transport connections */
+                           /* i.e. GND facility initialises cpcstart and cmcontact at the same time */
+    atn_conversation_t* cv; /* pointer to AARQ conversation */
+} aarq_data_t;
+
+wmem_tree_t *get_atn_conversation_tree(void);
+
+guint32 get_aircraft_24_bit_address_from_nsap(packet_info *);
+int check_heur_msg_type(packet_info *);
+
+#endif
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 4
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=4 tabstop=8 expandtab:
+ * :indentSize=4:tabSize=8:noTabs=true:
+ */