feat: DPLPMTUD

neqo-bin/src/lib.rs

@@ -118,6 +118,10 @@ pub struct QuicParameters {
     /// Whether to disable pacing.
     pub no_pacing: bool,
 
+    #[arg(long)]
+    /// Whether to disable path MTU discovery.
+    pub no_pmtud: bool,
+
     #[arg(name = "preferred-address-v4", long)]
     /// An IPv4 address for the server preferred address.
     pub preferred_address_v4: Option<String>,
@@ -137,6 +141,7 @@ impl Default for QuicParameters {
             idle_timeout: 30,
             congestion_control: CongestionControlAlgorithm::NewReno,
             no_pacing: false,
+            no_pmtud: false,
             preferred_address_v4: None,
             preferred_address_v6: None,
         }
@@ -203,7 +208,8 @@ impl QuicParameters {
             .max_streams(StreamType::UniDi, self.max_streams_uni)
             .idle_timeout(Duration::from_secs(self.idle_timeout))
             .cc_algorithm(self.congestion_control)
-            .pacing(!self.no_pacing);
+            .pacing(!self.no_pacing)
+            .pmtud(!self.no_pmtud);
 
         if let Some(&first) = self.quic_version.first() {
             let all = if self.quic_version[1..].contains(&first) {

neqo-http3/src/features/extended_connect/tests/webtransport/mod.rs

@@ -12,7 +12,7 @@ use std::{cell::RefCell, rc::Rc, time::Duration};
 
 use neqo_common::event::Provider;
 use neqo_crypto::AuthenticationStatus;
-use neqo_transport::{ConnectionParameters, StreamId, StreamType, MIN_INITIAL_PACKET_SIZE};
+use neqo_transport::{ConnectionParameters, Pmtud, StreamId, StreamType};
 use test_fixture::{
     anti_replay, fixture_init, now, CountingConnectionIdGenerator, DEFAULT_ADDR, DEFAULT_ALPN_H3,
     DEFAULT_KEYS, DEFAULT_SERVER_NAME,
@@ -25,7 +25,8 @@ use crate::{
     WebTransportServerEvent, WebTransportSessionAcceptAction,
 };
 
-const DATAGRAM_SIZE: u64 = MIN_INITIAL_PACKET_SIZE as u64;
+// Leave space for large QUIC header.
+const DATAGRAM_SIZE: u64 = Pmtud::default_plpmtu(DEFAULT_ADDR.ip()) as u64 - 40;
 
 pub fn wt_default_parameters() -> Http3Parameters {
     Http3Parameters::default()

neqo-transport/Cargo.toml

@@ -24,6 +24,7 @@ neqo-common = { path = "../neqo-common" }
 neqo-crypto = { path = "../neqo-crypto" }
 qlog = { workspace = true }
 smallvec = { version = "1.11", default-features = false }
+static_assertions = { version = "1.1", default-features = false }
 
 [dev-dependencies]
 criterion = { version = "0.5", default-features = false, features = ["html_reports"] }