1 files changed, 111 insertions, 0 deletions
diff --git a/third_party/rust/neqo-transport/tests/sim/net.rs b/third_party/rust/neqo-transport/tests/sim/net.rs
new file mode 100644
index 0000000000..754426f895
--- /dev/null
+++ b/third_party/rust/neqo-transport/tests/sim/net.rs
@@ -0,0 +1,111 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use super::rng::RandomDuration;
+use super::{Node, Rng};
+use neqo_common::Datagram;
+use neqo_transport::Output;
+use std::collections::BTreeMap;
+use std::fmt::{self, Debug};
+use std::iter;
+use std::ops::Range;
+use std::time::{Duration, Instant};
+
+/// 
+pub struct RandomDrop {
+    threshold: u64,
+    max: u64,
+    rng: Rng,
+}
+
+impl RandomDuration {
+    /// Make a new random `Duration` generator.  This asserts if the range provided
+    /// is inverted (i.e., `bounds.start > bounds.end`), or spans 2^64
+    /// or more nanoseconds.
+    /// A zero-length range means that random values won't be taken from the Rng
+    pub fn new(bounds: Range<Duration>, rng: Rng) -> Self {
+        let max = u64::try_from((bounds.end - bounds.start).as_nanos()).unwrap();
+        Self {
+            start: bounds.start,
+            max,
+            rng,
+        }
+    }
+
+    fn next(&mut self) -> Duration {
+        let r = if self.max == 0 {
+            Duration::new(0, 0)
+        } else {
+            self.rng.borrow_mut().random_from(0..self.max)
+        }
+        self.start + Duration::from_nanos(r)
+    }
+}
+
+enum DelayState {
+    New(Range<Duration>),
+    Ready(RandomDuration),
+}
+
+pub struct Delay {
+    state: DelayState,
+    queue: BTreeMap<Instant, Datagram>,
+}
+
+impl Delay
+{
+    pub fn new(bounds: Range<Duration>) -> Self
+    {
+        Self {
+            State: DelayState::New(bounds),
+            queue: BTreeMap::default(),
+        }
+    }
+
+    fn insert(&mut self, d: Datagram, now: Instant) {
+        let mut t = if let State::Ready(r) = self.state {
+        now + self.source.next()
+        } else {
+            unreachable!();
+        }
+        while self.queue.contains_key(&t) {
+            // This is a little inefficient, but it avoids drops on collisions,
+            // which are super-common for a fixed delay.
+            t += Duration::from_nanos(1);
+        }
+        self.queue.insert(t, d);
+    }
+}
+
+impl Node for Delay
+{
+    fn init(&mut self, rng: Rng, now: Instant) {
+        if let DelayState::New(bounds) = self.state {
+            self.state = RandomDuration::new(bounds);
+        } else {
+            unreachable!();
+        }
+    }
+
+    fn process(&mut self, d: Option<Datagram>, now: Instant) -> Output {
+        if let Some(dgram) = d {
+            self.insert(dgram, now);
+        }
+        if let Some((&k, _)) = self.queue.range(..now).nth(0) {
+            Output::Datagram(self.queue.remove(&k).unwrap())
+        } else if let Some(&t) = self.queue.keys().nth(0) {
+            Output::Callback(t - now)
+        } else {
+            Output::None
+        }
+    }
+}
+
+impl<T> Debug for Delay<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("delay")
+    }
+}