use batched reads

conn_helper_darwin.go

@@ -15,3 +15,7 @@ const (
 	msgTypeIPv4PKTINFO = unix.IP_PKTINFO
 	msgTypeIPv6PKTINFO = 0x2e
 )
+
+// ReadBatch only returns a single packet on OSX,
+// see https://godoc.org/golang.org/x/net/ipv4#PacketConn.ReadBatch.
+const batchSize = 1

conn_helper_freebsd.go

@@ -15,3 +15,5 @@ const (
 	msgTypeIPv4PKTINFO = 0x7
 	msgTypeIPv6PKTINFO = 0x2e
 )
+
+const batchSize = 8

conn_helper_linux.go

@@ -15,3 +15,5 @@ const (
 	msgTypeIPv4PKTINFO = unix.IP_PKTINFO
 	msgTypeIPv6PKTINFO = unix.IPV6_PKTINFO
 )
+
+const batchSize = 8 // needs to smaller than MaxUint8 (otherwise the type of oobConn.readPos has to be changed)

conn_oob.go

@@ -12,13 +12,27 @@ import (
 	"time"
 	"unsafe"
 
+	"golang.org/x/net/ipv4"
+	"golang.org/x/net/ipv6"
 	"golang.org/x/sys/unix"
 
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 )
 
-const ecnMask uint8 = 0x3
+const (
+	ecnMask       = 0x3
+	oobBufferSize = 128
+)
+
+// Contrary to what the naming suggests, the ipv{4,6}.Message is not dependent on the IP version.
+// They're both just aliases for x/net/internal/socket.Message.
+// This means we can use this struct to read from a socket that receives both IPv4 and IPv6 messages.
+var _ ipv4.Message = ipv6.Message{}
+
+type batchConn interface {
+	ReadBatch(ms []ipv4.Message, flags int) (int, error)
+}
 
 func inspectReadBuffer(c interface{}) (int, error) {
 	conn, ok := c.(interface {
@@ -43,7 +57,12 @@ func inspectReadBuffer(c interface{}) (int, error) {
 
 type oobConn struct {
 	OOBCapablePacketConn
-	oobBuffer []byte
+	batchConn batchConn
+
+	readPos uint8
+	// Packets received from the kernel, but not yet returned by ReadPacket().
+	messages []ipv4.Message
+	buffers  [batchSize]*packetBuffer
 }
 
 var _ connection = &oobConn{}
@@ -94,23 +113,41 @@ func newConn(c OOBCapablePacketConn) (*oobConn, error) {
 			return nil, errors.New("activating packet info failed for both IPv4 and IPv6")
 		}
 	}
-	return &oobConn{
+	oobConn := &oobConn{
 		OOBCapablePacketConn: c,
-		oobBuffer:            make([]byte, 128),
-	}, nil
+		batchConn:            ipv4.NewPacketConn(c),
+		messages:             make([]ipv4.Message, batchSize),
+		readPos:              batchSize,
+	}
+	for i := 0; i < batchSize; i++ {
+		oobConn.messages[i].OOB = make([]byte, oobBufferSize)
+	}
+	return oobConn, nil
 }
 
 func (c *oobConn) ReadPacket() (*receivedPacket, error) {
-	buffer := getPacketBuffer()
-	// The packet size should not exceed protocol.MaxPacketBufferSize bytes
-	// If it does, we only read a truncated packet, which will then end up undecryptable
-	buffer.Data = buffer.Data[:protocol.MaxPacketBufferSize]
-	c.oobBuffer = c.oobBuffer[:cap(c.oobBuffer)]
-	n, oobn, _, addr, err := c.OOBCapablePacketConn.ReadMsgUDP(buffer.Data, c.oobBuffer)
-	if err != nil {
-		return nil, err
+	if len(c.messages) == int(c.readPos) { // all messages read. Read the next batch of messages.
+		c.messages = c.messages[:batchSize]
+		// replace buffers data buffers up to the packet that has been consumed during the last ReadBatch call
+		for i := uint8(0); i < c.readPos; i++ {
+			buffer := getPacketBuffer()
+			buffer.Data = buffer.Data[:protocol.MaxPacketBufferSize]
+			c.buffers[i] = buffer
+			c.messages[i].Buffers = [][]byte{c.buffers[i].Data}
+		}
+		c.readPos = 0
+
+		n, err := c.batchConn.ReadBatch(c.messages, 0)
+		if n == 0 || err != nil {
+			return nil, err
+		}
+		c.messages = c.messages[:n]
 	}
-	ctrlMsgs, err := unix.ParseSocketControlMessage(c.oobBuffer[:oobn])
+
+	msg := c.messages[c.readPos]
+	buffer := c.buffers[c.readPos]
+	c.readPos++
+	ctrlMsgs, err := unix.ParseSocketControlMessage(msg.OOB[:msg.NN])
 	if err != nil {
 		return nil, err
 	}
@@ -129,13 +166,15 @@ func (c *oobConn) ReadPacket() (*receivedPacket, error) {
 				// 	struct in_addr ipi_addr;     /* Header Destination
 				// 									address */
 				// };
+				ip := make([]byte, 4)
 				if len(ctrlMsg.Data) == 12 {
 					ifIndex = binary.LittleEndian.Uint32(ctrlMsg.Data)
-					destIP = net.IP(ctrlMsg.Data[8:12])
+					copy(ip, ctrlMsg.Data[8:12])
 				} else if len(ctrlMsg.Data) == 4 {
 					// FreeBSD
-					destIP = net.IP(ctrlMsg.Data)
+					copy(ip, ctrlMsg.Data)
 				}
+				destIP = net.IP(ip)
 			}
 		}
 		if ctrlMsg.Header.Level == unix.IPPROTO_IPV6 {
@@ -148,7 +187,9 @@ func (c *oobConn) ReadPacket() (*receivedPacket, error) {
 				// 	unsigned int    ipi6_ifindex; /* send/recv interface index */
 				// };
 				if len(ctrlMsg.Data) == 20 {
-					destIP = net.IP(ctrlMsg.Data[:16])
+					ip := make([]byte, 16)
+					copy(ip, ctrlMsg.Data[:16])
+					destIP = net.IP(ip)
 					ifIndex = binary.LittleEndian.Uint32(ctrlMsg.Data[16:])
 				}
 			}
@@ -162,9 +203,9 @@ func (c *oobConn) ReadPacket() (*receivedPacket, error) {
 		}
 	}
 	return &receivedPacket{
-		remoteAddr: addr,
+		remoteAddr: msg.Addr,
 		rcvTime:    time.Now(),
-		data:       buffer.Data[:n],
+		data:       msg.Buffers[0][:msg.N],
 		ecn:        ecn,
 		info:       info,
 		buffer:     buffer,

conn_oob_test.go

@@ -3,11 +3,14 @@
 package quic
 
 import (
+	"fmt"
 	"net"
 	"time"
 
+	"golang.org/x/net/ipv4"
 	"golang.org/x/sys/unix"
 
+	"github.com/golang/mock/gomock"
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 
@@ -21,14 +24,14 @@ var _ = Describe("OOB Conn Test", func() {
 		Expect(err).ToNot(HaveOccurred())
 		udpConn, err := net.ListenUDP(network, addr)
 		Expect(err).ToNot(HaveOccurred())
-		ecnConn, err := newConn(udpConn)
+		oobConn, err := newConn(udpConn)
 		Expect(err).ToNot(HaveOccurred())
 
 		packetChan := make(chan *receivedPacket)
 		go func() {
 			defer GinkgoRecover()
 			for {
-				p, err := ecnConn.ReadPacket()
+				p, err := oobConn.ReadPacket()
 				if err != nil {
 					return
 				}
@@ -197,4 +200,43 @@ var _ = Describe("OOB Conn Test", func() {
 			Expect(p.info.addr).To(Equal(ip6))
 		})
 	})
+
+	Context("Batch Reading", func() {
+		var batchConn *MockBatchConn
+
+		BeforeEach(func() {
+			batchConn = NewMockBatchConn(mockCtrl)
+		})
+
+		It("reads multiple messages in one batch", func() {
+			const numMsgRead = batchSize/2 + 1
+			var counter int
+			batchConn.EXPECT().ReadBatch(gomock.Any(), gomock.Any()).DoAndReturn(func(ms []ipv4.Message, flags int) (int, error) {
+				Expect(ms).To(HaveLen(batchSize))
+				for i := 0; i < numMsgRead; i++ {
+					Expect(ms[i].Buffers).To(HaveLen(1))
+					Expect(ms[i].Buffers[0]).To(HaveLen(int(protocol.MaxPacketBufferSize)))
+					data := []byte(fmt.Sprintf("message %d", counter))
+					counter++
+					ms[i].Buffers[0] = data
+					ms[i].N = len(data)
+				}
+				return numMsgRead, nil
+			}).Times(2)
+
+			addr, err := net.ResolveUDPAddr("udp", "localhost:0")
+			Expect(err).ToNot(HaveOccurred())
+			udpConn, err := net.ListenUDP("udp", addr)
+			Expect(err).ToNot(HaveOccurred())
+			oobConn, err := newConn(udpConn)
+			Expect(err).ToNot(HaveOccurred())
+			oobConn.batchConn = batchConn
+
+			for i := 0; i < batchSize+1; i++ {
+				p, err := oobConn.ReadPacket()
+				Expect(err).ToNot(HaveOccurred())
+				Expect(string(p.data)).To(Equal(fmt.Sprintf("message %d", i)))
+			}
+		})
+	})
 })

mockgen.go

@@ -22,5 +22,6 @@ package quic
 //go:generate sh -c "./mockgen_private.sh quic mock_unknown_packet_handler_test.go github.com/lucas-clemente/quic-go unknownPacketHandler"
 //go:generate sh -c "./mockgen_private.sh quic mock_packet_handler_manager_test.go github.com/lucas-clemente/quic-go packetHandlerManager"
 //go:generate sh -c "./mockgen_private.sh quic mock_multiplexer_test.go github.com/lucas-clemente/quic-go multiplexer"
+//go:generate sh -c "./mockgen_private.sh quic mock_batch_conn_test.go github.com/lucas-clemente/quic-go batchConn"
 //go:generate sh -c "mockgen -package quic -self_package github.com/lucas-clemente/quic-go -destination mock_token_store_test.go github.com/lucas-clemente/quic-go TokenStore && goimports -w mock_token_store_test.go"
 //go:generate sh -c "mockgen -package quic -self_package github.com/lucas-clemente/quic-go -destination mock_packetconn_test.go net PacketConn && goimports -w mock_packetconn_test.go"