add a method to retrieve non-QUIC packets from the Transport (#3992)

integrationtests/self/multiplex_test.go

@@ -2,9 +2,11 @@ package self_test
 
 import (
 	"context"
+	"crypto/rand"
 	"io"
 	"net"
 	"runtime"
+	"sync/atomic"
 	"time"
 
 	"github.com/quic-go/quic-go"
@@ -210,4 +212,67 @@ var _ = Describe("Multiplexing", func() {
 			})
 		}
 	})
+
+	It("sends and receives non-QUIC packets", func() {
+		addr1, err := net.ResolveUDPAddr("udp", "localhost:0")
+		Expect(err).ToNot(HaveOccurred())
+		conn1, err := net.ListenUDP("udp", addr1)
+		Expect(err).ToNot(HaveOccurred())
+		defer conn1.Close()
+		tr1 := &quic.Transport{Conn: conn1}
+
+		addr2, err := net.ResolveUDPAddr("udp", "localhost:0")
+		Expect(err).ToNot(HaveOccurred())
+		conn2, err := net.ListenUDP("udp", addr2)
+		Expect(err).ToNot(HaveOccurred())
+		defer conn2.Close()
+		tr2 := &quic.Transport{Conn: conn2}
+
+		server, err := tr1.Listen(getTLSConfig(), getQuicConfig(nil))
+		Expect(err).ToNot(HaveOccurred())
+		runServer(server)
+		defer server.Close()
+
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		var sentPackets, rcvdPackets atomic.Int64
+		const packetLen = 128
+		// send a non-QUIC packet every 100µs
+		go func() {
+			defer GinkgoRecover()
+			ticker := time.NewTicker(time.Millisecond / 10)
+			defer ticker.Stop()
+			for {
+				select {
+				case <-ticker.C:
+				case <-ctx.Done():
+					return
+				}
+				b := make([]byte, packetLen)
+				rand.Read(b[1:]) // keep the first byte set to 0, so it's not classified as a QUIC packet
+				_, err := tr1.WriteTo(b, tr2.Conn.LocalAddr())
+				Expect(err).ToNot(HaveOccurred())
+				sentPackets.Add(1)
+			}
+		}()
+
+		// receive and count non-QUIC packets
+		go func() {
+			defer GinkgoRecover()
+			for {
+				b := make([]byte, 1024)
+				n, addr, err := tr2.ReadNonQUICPacket(ctx, b)
+				if err != nil {
+					Expect(err).To(MatchError(context.Canceled))
+					return
+				}
+				Expect(addr).To(Equal(tr1.Conn.LocalAddr()))
+				Expect(n).To(Equal(packetLen))
+				rcvdPackets.Add(1)
+			}
+		}()
+		dial(tr2, server.Addr())
+		Eventually(func() int64 { return sentPackets.Load() }).Should(BeNumerically(">", 10))
+		Eventually(func() int64 { return rcvdPackets.Load() }).Should(BeNumerically(">=", sentPackets.Load()*4/5))
+	})
 })