Commit eedee518 authored by Nick Mathewson's avatar Nick Mathewson 🦀
Browse files

Initial functions to determine and expose a clock skew estimate. 

(This is just a placeholder; I'm going to make the functions
smarter in the next commit.)
parent ae92f626

Cargo.lock

+1 −0
Original line number Diff line number Diff line
@@ -3463,6 +3463,7 @@ dependencies = [ 
 "derive_more",

 "educe",

 "futures",

 "humantime 2.1.0",

 "humantime-serde",

 "itertools",

 "pin-project",

crates/tor-guardmgr/Cargo.toml

+1 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ derive_builder = "0.11" 
derive_more = "0.99"

educe = "0.4.6"

futures = "0.3.14"

humantime = "2"

humantime-serde = "1.1.1"

itertools = "0.10.1"

pin-project = "1"

crates/tor-guardmgr/src/fallback/set.rs

+7 −0
Original line number Diff line number Diff line
@@ -215,6 +215,13 @@ impl FallbackState { 
            entry.status.clock_skew = Some(observation);

        }

    }



    /// Return an iterator over all the clock skew observations we've made for fallback directories

    pub(crate) fn skew_observations(&self) -> impl Iterator<Item = &SkewObservation> {

        self.fallbacks

            .iter()

            .filter_map(|fb| fb.status.clock_skew.as_ref())

    }

}



#[cfg(test)]

crates/tor-guardmgr/src/guard.rs

+6 −0
Original line number Diff line number Diff line
@@ -673,6 +673,12 @@ impl Guard { 
        self.clock_skew = Some(observation);

    }



    /// Return the most recent clock skew observation for this guard, if we have

    /// made one.

    pub(crate) fn skew(&self) -> Option<&SkewObservation> {

        self.clock_skew.as_ref()

    }



    /// Testing only: Return true if this guard was ever contacted successfully.

    #[cfg(test)]

    pub(crate) fn confirmed(&self) -> bool {

crates/tor-guardmgr/src/lib.rs

+17 −0
Original line number Diff line number Diff line
@@ -163,6 +163,7 @@ pub use err::{GuardMgrError, PickGuardError}; 
pub use filter::GuardFilter;

pub use ids::FirstHopId;

pub use pending::{GuardMonitor, GuardStatus, GuardUsable};

pub use skew::SkewEstimate;



use pending::{PendingRequest, RequestId};

use sample::GuardSet;
@@ -568,6 +569,14 @@ impl<R: Runtime> GuardMgr<R> { 
        );

    }



    /// Return our best estimate of our current clock skew, based on reports from the

    /// guards and fallbacks we have contacted.

    pub fn skew_estimate(&self) -> Option<SkewEstimate> {

        let inner = self.inner.lock().expect("Poisoned lock");

        let now = self.runtime.now();

        SkewEstimate::estimate_skew(inner.skew_observations(), now)

    }



    /// Ensure that the message queue is flushed before proceeding to

    /// the next step.  Used for testing.

    #[cfg(test)]
@@ -835,6 +844,14 @@ impl GuardMgrInner { 
        }

    }



    /// Return an iterator over all of the clock skew observations we've made

    /// for guards or fallbacks.

    fn skew_observations(&self) -> impl Iterator<Item = &skew::SkewObservation> {

        self.fallbacks

            .skew_observations()

            .chain(self.guards.active_guards().skew_observations())

    }



    /// If the circuit built because of a given [`PendingRequest`] may

    /// now be used (or discarded), return `Some(true)` or

    /// `Some(false)` respectively.