feat: calculate forward and backward loss (#860) - WIP

crates/trippy-core/src/state.rs

@@ -171,6 +171,10 @@ pub struct Hop {
     total_recv: usize,
     /// The total probes that failed for this hop.
     total_failed: usize,
+    /// The total forward loss for this hop.
+    total_forward_lost: usize,
+    /// The total backward loss for this hop.
+    total_backward_lost: usize,
     /// The total round trip time for this hop across all rounds.
     total_time: Duration,
     /// The round trip time for this hop in the current round.
@@ -239,6 +243,18 @@ impl Hop {
         self.total_recv
     }
 
+    /// The total number of probes with forward loss.
+    #[must_use]
+    pub const fn total_forward_loss(&self) -> usize {
+        self.total_forward_lost
+    }
+
+    /// The total number of probes with backward loss.
+    #[must_use]
+    pub const fn total_backward_loss(&self) -> usize {
+        self.total_backward_lost
+    }
+
     /// The total number of probes that failed.
     #[must_use]
     pub const fn total_failed(&self) -> usize {
@@ -256,6 +272,17 @@ impl Hop {
         }
     }
 
+    /// The adjusted % of packets that are lost.
+    #[must_use]
+    pub fn adjusted_loss_pct(&self) -> f64 {
+        if self.total_sent > 0 {
+            let lost = self.total_forward_lost;
+            lost as f64 / self.total_sent as f64 * 100f64
+        } else {
+            0_f64
+        }
+    }
+
     /// The duration of the last probe.
     #[must_use]
     pub fn last_ms(&self) -> Option<f64> {
@@ -367,6 +394,8 @@ impl Default for Hop {
             addrs: IndexMap::default(),
             total_sent: 0,
             total_recv: 0,
+            total_forward_lost: 0,
+            total_backward_lost: 0,
             total_failed: 0,
             total_time: Duration::default(),
             last: None,
@@ -471,12 +500,24 @@ impl FlowState {
         self.highest_ttl = std::cmp::max(self.highest_ttl, round.largest_ttl.0);
         self.highest_ttl_for_round = round.largest_ttl.0;
         let mut prev_hop_checksum = None;
+        let mut prev_hop_carry = false;
         for probe in round.probes {
-            self.update_from_probe(probe, &mut prev_hop_checksum);
+            self.update_from_probe(
+                round.probes,
+                probe,
+                &mut prev_hop_checksum,
+                &mut prev_hop_carry,
+            );
         }
     }
 
-    fn update_from_probe(&mut self, probe: &ProbeStatus, prev_hop_checksum: &mut Option<u16>) {
+    fn update_from_probe(
+        &mut self,
+        probes: &[ProbeStatus],
+        probe: &ProbeStatus,
+        prev_hop_checksum: &mut Option<u16>,
+        prev_hop_carry: &mut bool,
+    ) {
         match probe {
             ProbeStatus::Complete(complete) => {
                 self.update_lowest_ttl(complete.ttl);
@@ -541,6 +582,22 @@ impl FlowState {
                 self.hops[index].last_src_port = awaited.src_port.0;
                 self.hops[index].last_dest_port = awaited.dest_port.0;
                 self.hops[index].last_sequence = awaited.sequence.0;
+                if *prev_hop_carry {
+                    self.hops[index].total_backward_lost += 1;
+                } else if awaited.ttl.0 <= self.highest_ttl_for_round {
+                    // TODO panicked: range end index 17 out of range for slice of length 5
+                    let remaining = &probes[index..usize::from(self.highest_ttl_for_round)];
+                    if remaining.len() > 1 {
+                        let all_awaited = remaining
+                            .iter()
+                            .skip(1)
+                            .all(|p| matches!(p, ProbeStatus::Awaited(_)));
+                        if all_awaited {
+                            self.hops[index].total_forward_lost += 1;
+                            *prev_hop_carry = true;
+                        }
+                    }
+                }
             }
             ProbeStatus::Failed(failed) => {
                 self.update_lowest_ttl(failed.ttl);

crates/trippy-core/tests/resources/simulation/ipv4_icmp_loss.yaml

@@ -0,0 +1,37 @@
+name: IPv4/ICMP with 9 hops, 2 of which do not respond
+target: 10.0.0.109
+protocol: Icmp
+icmp_identifier: 3
+hops:
+  - ttl: 1
+    resp: !SingleHost
+      addr: 10.0.0.101
+      rtt_ms: 10
+  - ttl: 2
+    resp: NoResponse
+  - ttl: 3
+    resp: !SingleHost
+      addr: 10.0.0.103
+      rtt_ms: 20
+  - ttl: 4
+    resp: !SingleHost
+      addr: 10.0.0.104
+      rtt_ms: 20
+  - ttl: 5
+    resp: !SingleHost
+      addr: 10.0.0.105
+      rtt_ms: 20
+  - ttl: 6
+    resp: !SingleHost
+      addr: 10.0.0.106
+      rtt_ms: 20
+  - ttl: 7
+    resp: !SingleHost
+      addr: 10.0.0.107
+      rtt_ms: 20
+  - ttl: 8
+    resp: NoResponse
+  - ttl: 9
+    resp: !SingleHost
+      addr: 10.0.0.109
+      rtt_ms: 20

crates/trippy-tui/src/config/columns.rs

@@ -93,6 +93,12 @@ pub enum TuiColumn {
     LastNatStatus,
     /// The number of probes that failed for a hop.
     Failed,
+    /// The number of probes with forward loss.
+    Floss,
+    /// The number of probes with backward loss.
+    Bloss,
+    /// The loss percentage adjusted for back and forward loss.
+    AdjustedLossPct,
 }
 
 impl TryFrom<char> for TuiColumn {
@@ -122,6 +128,9 @@ impl TryFrom<char> for TuiColumn {
             'C' => Ok(Self::LastIcmpPacketCode),
             'N' => Ok(Self::LastNatStatus),
             'f' => Ok(Self::Failed),
+            'F' => Ok(Self::Floss),
+            'B' => Ok(Self::Bloss),
+            'A' => Ok(Self::AdjustedLossPct),
             c => Err(anyhow!(format!("unknown column code: {c}"))),
         }
     }
@@ -152,6 +161,9 @@ impl Display for TuiColumn {
             Self::LastIcmpPacketCode => write!(f, "C"),
             Self::LastNatStatus => write!(f, "N"),
             Self::Failed => write!(f, "f"),
+            Self::Floss => write!(f, "F"),
+            Self::Bloss => write!(f, "B"),
+            Self::AdjustedLossPct => write!(f, "A"),
         }
     }
 }

crates/trippy-tui/src/frontend/columns.rs

@@ -186,6 +186,12 @@ pub enum ColumnType {
     LastNatStatus,
     /// The number of probes that failed for a hop.
     Failed,
+    /// The number of probes with forward loss.
+    Floss,
+    /// The number of probes with backward loss.
+    Bloss,
+    /// The loss percentage adjusted for back and forward loss.
+    AdjustedLossPct,
 }
 
 impl From<ColumnType> for char {
@@ -213,6 +219,9 @@ impl From<ColumnType> for char {
             ColumnType::LastIcmpPacketCode => 'C',
             ColumnType::LastNatStatus => 'N',
             ColumnType::Failed => 'f',
+            ColumnType::Floss => 'F',
+            ColumnType::Bloss => 'B',
+            ColumnType::AdjustedLossPct => 'A',
         }
     }
 }
@@ -242,6 +251,9 @@ impl From<TuiColumn> for Column {
             TuiColumn::LastIcmpPacketCode => Self::new_shown(ColumnType::LastIcmpPacketCode),
             TuiColumn::LastNatStatus => Self::new_shown(ColumnType::LastNatStatus),
             TuiColumn::Failed => Self::new_shown(ColumnType::Failed),
+            TuiColumn::Floss => Self::new_shown(ColumnType::Floss),
+            TuiColumn::Bloss => Self::new_shown(ColumnType::Bloss),
+            TuiColumn::AdjustedLossPct => Self::new_shown(ColumnType::AdjustedLossPct),
         }
     }
 }
@@ -271,6 +283,9 @@ impl Display for ColumnType {
             Self::LastIcmpPacketCode => write!(f, "Code"),
             Self::LastNatStatus => write!(f, "Nat"),
             Self::Failed => write!(f, "Fail"),
+            Self::Floss => write!(f, "Floss"),
+            Self::Bloss => write!(f, "Bloss"),
+            Self::AdjustedLossPct => write!(f, "ALoss%"),
         }
     }
 }
@@ -302,6 +317,9 @@ impl ColumnType {
             Self::LastIcmpPacketCode => ColumnWidth::Fixed(7),
             Self::LastNatStatus => ColumnWidth::Fixed(7),
             Self::Failed => ColumnWidth::Fixed(7),
+            Self::Floss => ColumnWidth::Fixed(7),
+            Self::Bloss => ColumnWidth::Fixed(7),
+            Self::AdjustedLossPct => ColumnWidth::Fixed(8),
         }
     }
 }

crates/trippy-tui/src/frontend/render/table.rs

@@ -169,6 +169,9 @@ fn new_cell(
         ColumnType::LastIcmpPacketType => render_icmp_packet_type_cell(hop.last_icmp_packet_type()),
         ColumnType::LastIcmpPacketCode => render_icmp_packet_code_cell(hop.last_icmp_packet_type()),
         ColumnType::LastNatStatus => render_nat_cell(hop.last_nat_status()),
+        ColumnType::Floss => render_usize_cell(hop.total_forward_loss()),
+        ColumnType::Bloss => render_usize_cell(hop.total_backward_loss()),
+        ColumnType::AdjustedLossPct => render_adjusted_loss_pct_cell(hop),
     }
 }
 
@@ -188,6 +191,10 @@ fn render_loss_pct_cell(hop: &Hop) -> Cell<'static> {
     Cell::from(format!("{:.1}%", hop.loss_pct()))
 }
 
+fn render_adjusted_loss_pct_cell(hop: &Hop) -> Cell<'static> {
+    Cell::from(format!("{:.1}%", hop.adjusted_loss_pct()))
+}
+
 fn render_avg_cell(hop: &Hop) -> Cell<'static> {
     Cell::from(if hop.total_recv() > 0 {
         format!("{:.1}", hop.avg_ms())

trippy-config-sample.toml

@@ -282,6 +282,8 @@ tui-as-mode = "asn"
 #   C - Last icmp packet code
 #   N - Last NAT status
 #   f - Probes failed
+#   F = Probe forward loss
+#   B = Probe backward loss
 #
 # The columns will be shown in the order specified.
 tui-custom-columns = "holsravbwdt"