http3: add the qlog event schema to trace header (#5383)

http3/conn.go

@@ -66,7 +66,7 @@ func newConnection(
 	idleTimeout time.Duration,
 ) *Conn {
 	var qlogger qlogwriter.Recorder
-	if qlogTrace := quicConn.QlogTrace(); qlogTrace != nil {
+	if qlogTrace := quicConn.QlogTrace(); qlogTrace != nil && qlogTrace.SupportsSchemas(qlog.EventSchema) {
 		qlogger = qlogTrace.AddProducer()
 	}
 	c := &Conn{

http3/http3_helper_test.go

@@ -143,6 +143,8 @@ type qlogTrace struct {
 	recorder qlogwriter.Recorder
 }
 
+func (t *qlogTrace) SupportsSchemas(schema string) bool { return true }
+
 func (t *qlogTrace) AddProducer() qlogwriter.Recorder {
 	return t.recorder
 }

http3/qlog/qlog_dir.go

@@ -0,0 +1,15 @@
+package qlog
+
+import (
+	"context"
+
+	"github.com/quic-go/quic-go"
+	"github.com/quic-go/quic-go/qlog"
+	"github.com/quic-go/quic-go/qlogwriter"
+)
+
+const EventSchema = "urn:ietf:params:qlog:events:http3-12"
+
+func DefaultConnectionTracer(ctx context.Context, isClient bool, connID quic.ConnectionID) qlogwriter.Trace {
+	return qlog.DefaultConnectionTracerWithSchemas(ctx, isClient, connID, []string{qlog.EventSchema, EventSchema})
+}

http3/qlog/qlog_dir_test.go

@@ -0,0 +1,41 @@
+package qlog
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/quic-go/quic-go"
+	"github.com/quic-go/quic-go/qlog"
+	"github.com/stretchr/testify/require"
+)
+
+func TestQLOGDIRSet(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	connID := quic.ConnectionIDFromBytes([]byte{1, 2, 3, 4})
+	qlogDir := filepath.Join(tmpDir, "qlogs")
+	t.Setenv("QLOGDIR", qlogDir)
+
+	tracer := DefaultConnectionTracer(context.Background(), true, connID)
+	require.NotNil(t, tracer)
+
+	// adding and closing a producer makes the tracer close the file
+	recorder := tracer.AddProducer()
+	recorder.Close()
+
+	_, err := os.Stat(qlogDir)
+	qlogDirCreated := !os.IsNotExist(err)
+	require.True(t, qlogDirCreated)
+
+	entries, err := os.ReadDir(qlogDir)
+	require.NoError(t, err)
+	require.Len(t, entries, 1)
+
+	data, err := os.ReadFile(filepath.Join(qlogDir, entries[0].Name()))
+	require.NoError(t, err)
+
+	require.Contains(t, string(data), EventSchema)
+	require.Contains(t, string(data), qlog.EventSchema)
+}

http3/server.go

@@ -441,7 +441,7 @@ func (s *Server) removeListener(l *QUICListener) {
 // It blocks until all HTTP handlers for all streams have returned.
 func (s *Server) handleConn(conn *quic.Conn) error {
 	var qlogger qlogwriter.Recorder
-	if qlogTrace := conn.QlogTrace(); qlogTrace != nil {
+	if qlogTrace := conn.QlogTrace(); qlogTrace != nil && qlogTrace.SupportsSchemas(qlog.EventSchema) {
 		qlogger = qlogTrace.AddProducer()
 	}