read packets with the maximum packet size

fixes #467

buffer_pool.go

@@ -13,7 +13,7 @@ func getPacketBuffer() []byte {
 }
 
 func putPacketBuffer(buf []byte) {
-	if cap(buf) != int(protocol.MaxPacketSize) {
+	if cap(buf) != int(protocol.MaxReceivePacketSize) {
 		panic("putPacketBuffer called with packet of wrong size!")
 	}
 	bufferPool.Put(buf[:0])
@@ -21,6 +21,6 @@ func putPacketBuffer(buf []byte) {
 
 func init() {
 	bufferPool.New = func() interface{} {
-		return make([]byte, 0, protocol.MaxPacketSize)
+		return make([]byte, 0, protocol.MaxReceivePacketSize)
 	}
 }

buffer_pool_test.go

@@ -11,7 +11,7 @@ var _ = Describe("Buffer Pool", func() {
 	It("returns buffers of correct len and cap", func() {
 		buf := getPacketBuffer()
 		Expect(buf).To(HaveLen(0))
-		Expect(buf).To(HaveCap(int(protocol.MaxPacketSize)))
+		Expect(buf).To(HaveCap(int(protocol.MaxReceivePacketSize)))
 	})
 
 	It("zeroes put buffers' length", func() {
@@ -20,7 +20,7 @@ var _ = Describe("Buffer Pool", func() {
 			putPacketBuffer(buf[0:10])
 			buf = getPacketBuffer()
 			Expect(buf).To(HaveLen(0))
-			Expect(buf).To(HaveCap(int(protocol.MaxPacketSize)))
+			Expect(buf).To(HaveCap(int(protocol.MaxReceivePacketSize)))
 		}
 	})
 

client.go

@@ -115,7 +115,7 @@ func (c *client) listen() {
 		var n int
 		var addr net.Addr
 		data := getPacketBuffer()
-		data = data[:protocol.MaxPacketSize]
+		data = data[:protocol.MaxReceivePacketSize]
 
 		n, addr, err = c.conn.Read(data)
 		if err != nil {
@@ -141,7 +141,7 @@ func (c *client) listen() {
 }
 
 func (c *client) handlePacket(remoteAddr net.Addr, packet []byte) error {
-	if protocol.ByteCount(len(packet)) > protocol.MaxPacketSize {
+	if protocol.ByteCount(len(packet)) > protocol.MaxReceivePacketSize {
 		return qerr.PacketTooLarge
 	}
 

client_test.go

@@ -112,11 +112,6 @@ var _ = Describe("Client", func() {
 		Expect(err.(*qerr.QuicError).ErrorCode).To(Equal(qerr.InvalidPacketHeader))
 	})
 
-	It("errors on large packets", func() {
-		err := cl.handlePacket(nil, bytes.Repeat([]byte{'a'}, int(protocol.MaxPacketSize)+1))
-		Expect(err).To(MatchError(qerr.PacketTooLarge))
-	})
-
 	// this test requires a real session (because it calls the close callback) and a real UDP conn (because it unblocks and errors when it is closed)
 	It("properly closes", func(done Done) {
 		udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1)})
@@ -152,7 +147,7 @@ var _ = Describe("Client", func() {
 
 	Context("handling packets", func() {
 		It("errors on too large packets", func() {
-			err := cl.handlePacket(nil, bytes.Repeat([]byte{'f'}, int(protocol.MaxPacketSize+1)))
+			err := cl.handlePacket(nil, bytes.Repeat([]byte{'f'}, int(protocol.MaxReceivePacketSize+1)))
 			Expect(err).To(MatchError(qerr.PacketTooLarge))
 		})
 

protocol/protocol.go

@@ -36,12 +36,14 @@ type ByteCount uint64
 // MaxByteCount is the maximum value of a ByteCount
 const MaxByteCount = math.MaxUint64
 
-// MaxPacketSize is the maximum packet size, including the public header
+// CryptoStreamID is the ID of the crypto stream
-// This is the value used by Chromium for a QUIC packet sent using IPv6 (for IPv4 it would be 1370)
+const CryptoStreamID StreamID = 1
-const MaxPacketSize ByteCount = 1350
 
-// MaxFrameAndPublicHeaderSize is the maximum size of a QUIC frame plus PublicHeader
+// MaxReceivePacketSize maximum packet size of any QUIC packet, based on
-const MaxFrameAndPublicHeaderSize = MaxPacketSize - 12 /*crypto signature*/
+// ethernet's max size, minus the IP and UDP headers. IPv6 has a 40 byte header,
+// UDP adds an additional 8 bytes.  This is a total overhead of 48 bytes.
+// Ethernet's max packet size is 1500 bytes,  1500 - 48 = 1452.
+const MaxReceivePacketSize ByteCount = 1452
 
 // DefaultTCPMSS is the default maximum packet size used in the Linux TCP implementation.
 // Used in QUIC for congestion window computations in bytes.

protocol/server_parameters.go

@@ -2,6 +2,13 @@ package protocol
 
 import "time"
 
+// MaxPacketSize is the maximum packet size, including the public header, that we use for sending packets
+// This is the value used by Chromium for a QUIC packet sent using IPv6 (for IPv4 it would be 1370)
+const MaxPacketSize ByteCount = 1350
+
+// MaxFrameAndPublicHeaderSize is the maximum size of a QUIC frame plus PublicHeader
+const MaxFrameAndPublicHeaderSize = MaxPacketSize - 12 /*crypto signature*/
+
 // NonForwardSecurePacketSizeReduction is the number of bytes a non forward-secure packet has to be smaller than a forward-secure packet
 // This makes sure that those packets can always be retransmitted without splitting the contained StreamFrames
 const NonForwardSecurePacketSizeReduction = 50

server.go

@@ -83,7 +83,7 @@ func Listen(conn net.PacketConn, config *Config) (Listener, error) {
 func (s *server) Serve() error {
 	for {
 		data := getPacketBuffer()
-		data = data[:protocol.MaxPacketSize]
+		data = data[:protocol.MaxReceivePacketSize]
 		n, remoteAddr, err := s.conn.ReadFrom(data)
 		if err != nil {
 			if strings.HasSuffix(err.Error(), "use of closed network connection") {
@@ -122,7 +122,7 @@ func (s *server) Addr() net.Addr {
 }
 
 func (s *server) handlePacket(pconn net.PacketConn, remoteAddr net.Addr, packet []byte) error {
-	if protocol.ByteCount(len(packet)) > protocol.MaxPacketSize {
+	if protocol.ByteCount(len(packet)) > protocol.MaxReceivePacketSize {
 		return qerr.PacketTooLarge
 	}
 

server_test.go

@@ -253,7 +253,7 @@ var _ = Describe("Server", func() {
 		})
 
 		It("errors on large packets", func() {
-			err := serv.handlePacket(nil, nil, bytes.Repeat([]byte{'a'}, int(protocol.MaxPacketSize)+1))
+			err := serv.handlePacket(nil, nil, bytes.Repeat([]byte{'a'}, int(protocol.MaxReceivePacketSize)+1))
 			Expect(err).To(MatchError(qerr.PacketTooLarge))
 		})