Appendix 2.A Message Reference

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2.A.1 Messages #

2.A.1.1 On `/run/logon.sock` #

`msg_type`	Message	Direction	Defined in
`0x0001`	`LogonStart`	client → authority	§2.7
`0x0002`	`CredentialResponse`	client → authority	§2.8
`0x8001`	`CredentialRequest`	authority → client	§2.8
`0x8002`	`AccessGranted`	authority → client	§2.9
`0x8003`	`AccessDenied`	authority → client	§2.10

2.A.1.2 On `/run/ident.sock` #

`msg_type`	Message	Direction	Defined in
`0x0010`	`Lookup`	client → authority	§2.16
`0x0011`	`Enumerate`	client → authority	§2.17
`0x8010`	`LookupReply`	authority → client	§2.16
`0x8011`	`EnumerateReply`	authority → client	§2.17

The high bit marks a message sent by the authority (§2.6). The two ranges are disjoint, and a message of one range MUST be refused on the other socket (§2.14).

2.A.2 Protocol constants #

Constant	Value	Defined in
Logon socket path	`/run/logon.sock`	§2.5
Identity socket path	`/run/ident.sock`	§2.14
Magic	`PGSL` (`50 47 53 4c`)	§2.6
Version	`1`	§2.6
Header size	12 bytes	§2.6
Maximum message size	65536 bytes	§2.6

2.A.3 Field limits #

Field	Maximum	Defined in
`identifier`	1024 bytes	§2.7
`tty`	128 bytes	§2.7
`remote_host`	256 bytes	§2.7
`supported_credential_types`	32 entries	§2.7
`messages`	8 entries	§2.8
`prompts`	16 entries	§2.8
`answers`	16 entries	§2.8
`text`	512 bytes	§2.8
`credential_name`	128 bytes	§2.8
`data`	32768 bytes	§2.8
`home`	4096 bytes	§2.9
`shell`	4096 bytes	§2.9
`display_name`	256 bytes	§2.9
`reason`	512 bytes	§2.10
`name` (lookup key)	256 bytes	§2.16
`sid`	68 bytes	§2.16
`qualified_name`	512 bytes	§2.16
`withheld`	32 entries	§2.16
`values`	32 entries	§2.16
reference `name`	512 bytes	§2.16
`HOME`, `SHELL`	4096 bytes	§2.16
`DISPLAY_NAME`	256 bytes	§2.16
`GROUPS`	128 entries	§2.16
`MEMBERS`	256 entries	§2.16
`CLAIMS`	64 entries	§2.16
`of_name`	256 bytes	§2.17
`cursor`, `next`	256 bytes	§2.17
`entries`	256 entries	§2.17
`incomplete`	32 entries	§2.17
`incomplete` source name	32 bytes	§2.17

The 68-byte SID maximum is a property of the SID encoding rather than of this chapter: an eight-byte prelude plus the fifteen sub-authorities the one-byte count admits. It is specified in PCDS.

An encoder MUST refuse to produce a field exceeding its maximum; a decoder MUST reject one it receives (§2.6).

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