Struct SessionSetup 

pub struct SessionSetup {
    pub src_coords: TreeCoordinate,
    pub dest_coords: TreeCoordinate,
    pub flags: SessionFlags,
    pub handshake_payload: Vec<u8>,
}

Session setup to establish cached coordinate state.

Carried inside a SessionDatagram envelope which provides src_addr and dest_addr. The SessionSetup payload contains coordinates, session flags, and the Noise XK handshake message for session establishment.

SessionSetup, SessionAck, and SessionMsg3 are identified by the phase field in the FSP common prefix (0x1, 0x2, 0x3), not by a message-type byte. The msg_type field in the encrypted inner header applies only to established-phase (0x0) messages.

Wire Format

Encoded with FSP common prefix: [ver_phase:1][flags:1][payload_len:2 LE][body], where ver_phase = 0x01 (version 0, phase MSG1) and flags = 0 for handshake.

Body (after 4-byte FSP prefix):

Offset	Field	Size	Description
0	flags	1 byte	Bit 0: REQUEST_ACK, Bit 1: BIDIRECTIONAL
1	src_coords_count	2 bytes LE	Number of source coordinate entries
3	src_coords	16 × n	Source’s ancestry (NodeAddr, self → root)
…	dest_coords_count	2 bytes LE	Number of dest coordinate entries
…	dest_coords	16 × m	Destination’s ancestry
…	handshake_len	2 bytes LE	Noise payload length
…	handshake_payload	variable	Noise XK msg1 (33 bytes — ephemeral key only)

Fields

src_coords: TreeCoordinate

Source coordinates (for return path caching).

dest_coords: TreeCoordinate

Destination coordinates (for forward routing).

flags: SessionFlags

Session options.

handshake_payload: Vec<u8>

Noise IK handshake message 1.

Implementations

impl SessionSetup

pub fn new(src_coords: TreeCoordinate, dest_coords: TreeCoordinate) -> Self

Create a new session setup message.

pub fn with_flags(self, flags: SessionFlags) -> Self

Set session flags.

pub fn with_handshake(self, payload: Vec<u8>) -> Self

Set the Noise handshake payload.

pub fn encode(&self) -> Vec<u8>

Encode as wire format (4-byte FSP prefix + flags + coords + handshake).

The 4-byte prefix: [ver_phase:1][flags:1][payload_len:2 LE] where ver_phase = 0x01 (version 0, phase MSG1).

pub fn decode(payload: &[u8]) -> Result<Self, ProtocolError>

Decode from wire format (after 4-byte FSP prefix has been consumed).

Trait Implementations

impl Clone for SessionSetup

fn clone(&self) -> SessionSetup

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SessionSetup

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.