Parameter Values (PV)

class icspacket.proto.iso_ses.values.PI_Code(*values)

Common Parameter Identifier (PI) codes. (See X.225, 8.3)

Note

• Not all PI codes are mapped to PV implementations here; only those with common, structured bitfield encodings are represented.

• Other PIs may be treated as raw byte values in other parts of the parser.

class icspacket.proto.iso_ses.values.PV_VersionNumber(reserved: int = 0, version2: bool = True, version1: bool = False)

Version Number PV. (See X.225)

Flags which protocol version(s) this endpoint is willing to run; sent in the CONNECT SPDU and echoed back in the ACCEPT SPDU once the peer has picked one.

version2: bool = True

True if Protocol Version 2 is proposed.

version1: bool = False

True if Protocol Version 1 is proposed.

class icspacket.proto.iso_ses.values.PV_TokenSettingPairType(*values)

The four values a 2-bit token-setting slot can take.

Each slot fixes where one of the session’s tokens starts out:

• 0 - held by the initiator from the start

• 1 - held by the responder from the start

• 2 - left for the SS-user to decide (“user’s choice”)

• 3 - reserved, not currently assigned a meaning

class icspacket.proto.iso_ses.values.PV_TokenSetting(release: PV_TokenSettingPairType = PV_TokenSettingPairType.INITIATOR, activity: PV_TokenSettingPairType = PV_TokenSettingPairType.INITIATOR, sync: PV_TokenSettingPairType = PV_TokenSettingPairType.INITIATOR, data: PV_TokenSettingPairType = PV_TokenSettingPairType.INITIATOR)

Token Setting Item PV. (See X.225)

When present, assigns a starting holder to each of the four session tokens listed below, using the slot values from PV_TokenSettingPairType.

release: PV_TokenSettingPairType = 0

Initial position of the release token.

activity: PV_TokenSettingPairType = 0

Initial position of the activity token.

sync: PV_TokenSettingPairType = 0

Initial position of the synchronization token.

data: PV_TokenSettingPairType = 0

Initial position of the data token.

class icspacket.proto.iso_ses.values.PV_TokenItem(_reserved_1: bool = 0, release_token: bool = False, _reserved_2: bool = 0, activity_token: bool = False, _reserved_3: bool = 0, sync_minor_token: bool = False, _reserved_4: bool = 0, data_token: bool = False)

Token Item PV. (See X.225)

Each bit is a request flag the called SS-user sets to claim one of the four session tokens listed below.

release_token: bool = False

Request for the release token.

activity_token: bool = False

Request for the activity token.

sync_minor_token: bool = False

Request for the minor sync token.

data_token: bool = False

Request for the data token.

class icspacket.proto.iso_ses.values.PV_TransportDisconnect(_reserved: int = 0, implementation_restriction: bool = False, no_reason: bool = False, protocol_error: bool = False, user_abort: bool = False, release_transport: bool = True)

Transport Disconnect PV. (See X.225)

Carried in the ABORT SPDU: one bit says whether the transport connection should be released or kept alive, and the rest record which abort reason triggered the message.

class icspacket.proto.iso_ses.values.PV_SessionRequirements(_reserved: int = 0, data_separation: bool = False, symmetric_sync: bool = False, typed: bool = False, exceptions: bool = False, capability_data_exchange: bool = False, negotiated_release: bool = False, activity_management: bool = False, resync: bool = False, major_sync: bool = False, minor_sync: bool = False, expedited: bool = False, duplex: bool = False, half_duplex: bool = False)

Session Requirements PV. (See X.225)

Sent by the calling SS-user in the CONNECT SPDU to advertise which optional functional units (listed below) it wants active for the session; the responder echoes back the subset it accepts in the ACCEPT SPDU.

data_separation: bool = False

Functional unit: Data separation

symmetric_sync: bool = False

Functional unit: Symmetric synchronization

typed: bool = False

Functional unit: Typed data

exceptions: bool = False

Functional unit: Exceptions

capability_data_exchange: bool = False

Functional unit: Capability data exchange

negotiated_release: bool = False

Functional unit: Negotiated release

activity_management: bool = False

Functional unit: Activity management

resync: bool = False

Functional unit: Resynchronization

major_sync: bool = False

Functional unit: Major synchronization

minor_sync: bool = False

Functional unit: Minor synchronization

expedited: bool = False

Functional unit: Expedited data

duplex: bool = False

Functional unit: Full-duplex

half_duplex: bool = False

Functional unit: Half-duplex

classmethod default() → PV_SessionRequirements

Return the default client functional-unit proposal.

update(accepted: PV_SessionRequirements) → PV_SessionRequirements

Return the functional units selected by both peers.

property is_empty: bool

Whether no functional units are proposed.

class icspacket.proto.iso_ses.values.PV_EnclosureItem(_reserved: int = 0, end: bool = False, start: bool = False)

Enclosure Item PV. (See X.225)

Two independent flags marking whether the carrying SPDU is the start and/or the end of an SSDU.

end: bool = False

True if this SPDU is the end of the SSDU.

start: bool = False

True if this SPDU is the start of the SSDU.

class icspacket.proto.iso_ses.values.PV_ProtocolOptions(_reserved: int = 0, extended: bool = False)

Protocol Options PV. (See X.225, §8.3.19)

Single capability flag sent in the CONNECT SPDU and echoed in the ACCEPT SPDU, advertising support for receiving extended concatenated SPDUs.

extended: bool = False

True if extended concatenated SPDUs are supported.

class icspacket.proto.iso_ses.values.PV_DataOverflow(_reserved: int = 0, overflow: bool = True)

Data Overflow PV. (See X.225)

icspacket.proto.iso_ses.values.PV_TYPES = {PI_Code.TOKEN_ITEM: <class 'icspacket.proto.iso_ses.values.PV_TokenItem'>, PI_Code.TRANSPORT_DISCONNECT: <class 'icspacket.proto.iso_ses.values.PV_TransportDisconnect'>, PI_Code.PROTOCOL_OPTIONS: <class 'icspacket.proto.iso_ses.values.PV_ProtocolOptions'>, PI_Code.SESSION_REQUIREMENT: <class 'icspacket.proto.iso_ses.values.PV_SessionRequirements'>, PI_Code.TSDU_MAXIMUM_SIZE: <int32>, PI_Code.VERSION_NUMBER: <class 'icspacket.proto.iso_ses.values.PV_VersionNumber'>, PI_Code.ENCLOSUREITEM: <class 'icspacket.proto.iso_ses.values.PV_EnclosureItem'>, PI_Code.TOKEN_SETTING_ITEM: <class 'icspacket.proto.iso_ses.values.PV_TokenSetting'>, PI_Code.DATA_OVERFLOW: <class 'icspacket.proto.iso_ses.values.PV_DataOverflow'>}

Mapping from PI codes to their associated Parameter Value types.

This table is used during SPDU parameter decoding to instantiate the right PV object.