feat(client): add --timeouts option for session-opening retry schedule

crates/irtt-app/src/shared/client/args.rs

@@ -22,6 +22,10 @@ pub struct CommonClientArgs {
     #[arg(short = 'i', long, default_value = "1s", value_parser = parse_duration)]
     pub interval: Duration,
 
+    /// Comma-separated session-opening timeouts, one per attempt (each >= 200ms).
+    #[arg(long, value_name = "DURATIONS", value_delimiter = ',', value_parser = parse_duration, long_help = "Comma-separated session-opening receive timeouts, one per attempt (each at least 200ms), e.g. 1s,2s,4s,8s. Omit to use the library default retry schedule.")]
+    pub timeouts: Vec<Duration>,
+
     /// UDP payload length.
     #[arg(short = 'l', long, default_value_t = 0, value_parser = parse_length)]
     pub length: u32,
@@ -116,6 +120,7 @@ impl fmt::Debug for CommonClientArgs {
             .field("ipv6", &self.ipv6)
             .field("dual_stack", &self.dual_stack)
             .field("interval", &self.interval)
+            .field("timeouts", &self.timeouts)
             .field("length", &self.length)
             .field("hmac", &self.hmac.as_ref().map(|_| "[REDACTED]"))
             .field("clock", &self.clock)

crates/irtt-app/src/shared/client/config.rs

@@ -22,16 +22,21 @@ impl CommonClientArgs {
     ///
     /// The config is endpoint-independent; managed targets own their addresses.
     pub fn to_client_config(&self, duration: Duration) -> Result<ClientConfig, String> {
+        let mut open = OpenPolicy {
+            negotiation: if self.loose {
+                NegotiationPolicy::Loose
+            } else {
+                NegotiationPolicy::Strict
+            },
+            ..Default::default()
+        };
+        if !self.timeouts.is_empty() {
+            open.timeouts.clone_from(&self.timeouts);
+        }
+
         Ok(ClientConfig {
             address_family: self.address_family(),
-            open: OpenPolicy {
+            open,
-                negotiation: if self.loose {
-                    NegotiationPolicy::Loose
-                } else {
-                    NegotiationPolicy::Strict
-                },
-                ..Default::default()
-            },
             request: SessionRequest {
                 duration: (!duration.is_zero()).then_some(duration),
                 interval: self.interval,

docs/irtt-client.md

@@ -180,6 +180,12 @@ expansion: a hostname producing both families consumes two target slots.
 be greater than zero; a zero test duration, including `0s`, selects continuous
 mode.
 
+`--timeouts 1s,2s,4s,8s` sets the session-opening retry schedule. Each
+comma-separated duration is the receive timeout for one open attempt; attempts
+stop when a valid open reply arrives. The list must be nonempty, with each
+value at least `200ms`, and uses the same duration syntax as `--interval`.
+Omitting the option preserves the library default schedule.
+
 `--duration` controls the run length:
 
 - Any nonzero duration (default `10s`) is a **finite** run: probing stops

docs/irtt-tui.md

@@ -16,9 +16,9 @@ At least one target is required.
 
 Target syntax, multiple targets, and pacing are identical to
 `irtt-client(1)` — see that manual for `[LABEL=]TARGET` syntax and the
-`--pacing staggered|burst` option. The full set of negotiation flags
+`--pacing staggered|burst` option. The client configuration flags
-(`--interval`, `--length`, `--hmac`, `--clock`, `--tstamp`, `--stats`,
+(`--interval`, `--timeouts`, `--length`, `--hmac`, `--clock`, `--tstamp`,
-`--sfill`, `--dscp`, `--ttl`, `--loose`) is shared with `irtt-client` as
+`--stats`, `--sfill`, `--dscp`, `--ttl`, `--loose`) are shared with `irtt-client` as
 well; consult that manual for their meaning.
 
 Address-family controls are shared too: `-4` / `--ipv4` uses IPv4 only,