SimTX API v24/Packets/Handshake

Handshake

Packet ID	—
Direction	Client → server
Session	All roles
Body size	12 bytes + credential
Permission	None
Answered by	HandshakeResult
Answers

The Handshake is the first data a client sends on a new connection, immediately after the TLS handshake. It identifies the protocol, states the protocol version, selects the session role, and optionally carries a game ticket. Unlike every other packet, it has no packet ID byte.

Layout

Field	Type	Description
magic	i32	Always 0x53494D54, the ASCII bytes SIMT.
version	i32	Protocol version. Must be 24.
role	u8	Session role. See Roles.
authKind	u8	0 = ANONYMOUS, 1 = GAME_TICKET.
credential	UTF	Empty for anonymous connections. Otherwise the stx_gt1_ ticket. At most 512 characters, no control characters.

Roles

Byte	Role	Authentication
1	RECEIVER	Anonymous, or ticket role receiver
2	TX_AUDIO	Ticket role tx-audio
3	TX_GENERATED	Ticket role tx-generated
4	CONTROL	Anonymous, or ticket role control
5	MODERATION	Ticket role moderation
6	TIMESTAMPED_RECEIVER	Anonymous only

Validation

• authKind = 0 requires an empty credential; authKind = 1 requires a non-blank one.
• A wrong magic number, an unknown authKind, or an illegal credential (too long, control characters, or inconsistent with authKind) closes the connection without a reply.
• A wrong version is answered with HandshakeResult status VERSION_UNSUPPORTED.
• The handshake and the first session request must arrive within 5 seconds through the public gateway (15 seconds on a direct server).

Example

Transmitter handshake with a ticket (ticket shortened):

53 49 4D 54           magic       "SIMT"
00 00 00 18           version     24
02                    role        TX_AUDIO
01                    authKind    GAME_TICKET
00 48                 credential  length 72
73 74 78 5F 67 74 31 5F …         "stx_gt1_…"

See also

• SimTX API v24/Connection and handshake
• SimTX API v24/Game tickets