Struct PathBuilder

pub(super) struct PathBuilder<'n, 'a, RT: Runtime, R: Rng> {
    hops: Vec<MaybeOwnedRelay<'n>>,
    netdir: &'n NetDir,
    vanguards: &'a VanguardMgr<RT>,
    rng: &'a mut R,
    last_hop_kind: HopKind,
}

Available on crate features hs-common and vanguards only.

A vanguard path builder.

A PathBuilder is a state machine whose current state is the HopKind of its last hop. Not all state transitions are valid. For the permissible state transitions, see update_last_hop_kind.

This type is an implementation detail that should remain private. Used by VanguardHsPathBuilder.

Fields

hops: Vec<MaybeOwnedRelay<'n>>

The relays in the path.

netdir: &'n NetDir

The network directory.

vanguards: &'a VanguardMgr<RT>

The vanguard manager.

rng: &'a mut R

An RNG for selecting vanguards and middle relays.

last_hop_kind: HopKind

The HopKind of the last hop in the path.

Implementations

impl<'n, 'a, RT: Runtime, R: Rng> PathBuilder<'n, 'a, RT, R>

pub(super) fn new( rng: &'a mut R, netdir: &'n NetDir, vanguards: &'a VanguardMgr<RT>, l1_guard: MaybeOwnedRelay<'n>, ) -> Self

Create a new PathBuilder.

pub(super) fn add_vanguard( self, selector: &RelaySelector<'n>, layer: Layer, ) -> Result<Self>

Extend the path with a vanguard.

pub(super) fn add_middle(self, selector: &RelaySelector<'n>) -> Result<Self>

Extend the path with a middle relay.

pub(super) fn build(self) -> Result<TorPath<'n>>

Return a TorPath built using the hops from this PathBuilder.

fn add_hop( &mut self, hop: MaybeOwnedRelay<'n>, hop_kind: HopKind, ) -> StdResult<(), Bug>

Try to append hop to the end of the path.

This also causes the PathBuilder to transition to the state represented by hop_kind, if the transition is valid.

Returns an error if the hop_kind is incompatible with the HopKind of the last hop.

fn update_last_hop_kind(&mut self, kind: HopKind) -> StdResult<(), Bug>

Transition to the state specified by kind.

The state of the PathBuilder is represented by the HopKind of its last hop. This function should be called whenever a new hop is added (e.g. in add_hop), to set the current state to the HopKind of the new hop.

Not all transitions are valid. The permissible state transitions are:

• G -> L2
• L2 -> L3
• L2 -> M
• L3 -> M