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fix(wt_bridge): default QUIC initial packet size to 1200 for VPN paths #373

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Merged
osamu620 merged 1 commit into from
May 11, 2026
Merged

fix(wt_bridge): default QUIC initial packet size to 1200 for VPN paths #373

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7 changes: 5 additions & 2 deletions tools/wt_bridge/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -32,12 +32,16 @@ func main() {
certPath = flag.String("cert", "", "PEM cert chain (use instead of --dev for a CA-issued cert)")
keyPath = flag.String("key", "", "PEM private key matching --cert")
dev = flag.Bool("dev", false, "Generate an ephemeral self-signed cert and print SHA-256 hash")
initialMTU = flag.Int("initial-mtu", 1200, "Initial QUIC packet size in bytes (1200-1452); lower for VPN/tunnel paths")
)
flag.Parse()

if !*dev && (*certPath == "" || *keyPath == "") {
log.Fatalf("either --dev or both --cert and --key are required")
}
if *initialMTU < 1200 || *initialMTU > 1452 {
log.Fatalf("--initial-mtu must be between 1200 and 1452")
}
log.SetFlags(log.LstdFlags | log.Lmicroseconds)

udpAddr, err := net.ResolveUDPAddr("udp", *listenUDP)
Expand Down Expand Up @@ -83,11 +87,10 @@ func main() {
NextProtos: []string{http3.NextProtoH3},
}
quicConf := &quic.Config{
// Generous datagram allowance — even though we use streams for the
// data path, control-plane flow benefits from a steady idle timeout.
MaxIdleTimeout: 30 * time.Second,
KeepAlivePeriod: 10 * time.Second,
EnableDatagrams: true,
InitialPacketSize: uint16(*initialMTU),
}

wtServer := &webtransport.Server{
Expand Down
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