diff --git a/README.md b/README.md
index c0251d9..fcb670d 100644
--- a/README.md
+++ b/README.md
@@ -71,7 +71,7 @@ we can set up local listeners as proxy servers, and forward requests to internet
 Binary Download:
 - [https://github.com/nadoo/glider/releases](https://github.com/nadoo/glider/releases)
 
-Build from source code (requires **Go 1.14+** ):
+Build from source code (requires **Go 1.15+** ):
 ```bash
 git clone https://github.com/nadoo/glider
 cd glider && go build
diff --git a/common/conn/conn.go b/common/conn/conn.go
index e156fd4..e697bb2 100644
--- a/common/conn/conn.go
+++ b/common/conn/conn.go
@@ -2,22 +2,25 @@ package conn
 
 import (
 	"bufio"
+	"errors"
 	"io"
 	"net"
+	"os"
+	"sync"
 	"time"
 
 	"github.com/nadoo/glider/common/pool"
 )
 
 const (
-	// TCPBufSize is the size of tcp buffer
+	// TCPBufSize is the size of tcp buffer.
 	TCPBufSize = 16 << 10
 
-	// UDPBufSize is the size of udp buffer
+	// UDPBufSize is the size of udp buffer.
 	UDPBufSize = 64 << 10
 )
 
-// Conn is a base conn struct
+// Conn is a connection with buffered reader.
 type Conn struct {
 	r *bufio.Reader
 	net.Conn
@@ -43,35 +46,39 @@ func (c *Conn) Reader() *bufio.Reader {
 }
 
 // Relay relays between left and right.
-func Relay(left, right net.Conn) (int64, int64, error) {
-	type res struct {
-		N   int64
-		Err error
-	}
-	ch := make(chan res)
+func Relay(left, right net.Conn) error {
+	var err, err1 error
+	var wg sync.WaitGroup
+	var wait = 5 * time.Second
 
+	wg.Add(1)
 	go func() {
-		b := pool.GetBuffer(TCPBufSize)
-		n, err := io.CopyBuffer(right, left, b)
-		pool.PutBuffer(b)
-
-		right.SetDeadline(time.Now()) // wake up the other goroutine blocking on right
-		left.SetDeadline(time.Now())  // wake up the other goroutine blocking on left
-		ch <- res{n, err}
+		defer wg.Done()
+		_, err1 = Copy(right, left)
+		right.SetReadDeadline(time.Now().Add(wait)) // unblock read on right
 	}()
 
-	b := pool.GetBuffer(TCPBufSize)
-	n, err := io.CopyBuffer(left, right, b)
-	pool.PutBuffer(b)
+	_, err = Copy(left, right)
+	left.SetReadDeadline(time.Now().Add(wait)) // unblock read on left
+	wg.Wait()
 
-	right.SetDeadline(time.Now()) // wake up the other goroutine blocking on right
-	left.SetDeadline(time.Now())  // wake up the other goroutine blocking on left
-	rs := <-ch
-
-	if err == nil {
-		err = rs.Err
+	if err1 != nil && !errors.Is(err1, os.ErrDeadlineExceeded) { // requires Go 1.15+
+		return err1
 	}
-	return n, rs.N, err
+
+	if err != nil && !errors.Is(err, os.ErrDeadlineExceeded) {
+		return err
+	}
+
+	return nil
+}
+
+// Copy copies from src to dst.
+func Copy(dst io.Writer, src io.Reader) (written int64, err error) {
+	buf := pool.GetBuffer(TCPBufSize)
+	defer pool.PutBuffer(buf)
+
+	return io.CopyBuffer(dst, src, buf)
 }
 
 // RelayUDP copys from src to dst at target with read timeout.
diff --git a/dns/server.go b/dns/server.go
index d6c1556..6acf529 100644
--- a/dns/server.go
+++ b/dns/server.go
@@ -49,20 +49,20 @@ func (s *Server) Start() {
 
 // ListenAndServeUDP listen and serves on udp port.
 func (s *Server) ListenAndServeUDP(wg *sync.WaitGroup) {
-	c, err := net.ListenPacket("udp", s.addr)
+	pc, err := net.ListenPacket("udp", s.addr)
 	wg.Done()
 	if err != nil {
 		log.F("[dns] failed to listen on %s, error: %v", s.addr, err)
 		return
 	}
-	defer c.Close()
+	defer pc.Close()
 
 	log.F("[dns] listening UDP on %s", s.addr)
 
 	for {
 		reqBytes := pool.GetBuffer(UDPMaxLen)
 
-		n, caddr, err := c.ReadFrom(reqBytes[2:])
+		n, caddr, err := pc.ReadFrom(reqBytes[2:])
 		if err != nil {
 			log.F("[dns] local read error: %v", err)
 			pool.PutBuffer(reqBytes)
@@ -77,27 +77,28 @@ func (s *Server) ListenAndServeUDP(wg *sync.WaitGroup) {
 		}
 		binary.BigEndian.PutUint16(reqBytes[:2], reqLen)
 
-		go func() {
-			respBytes, err := s.Exchange(reqBytes[:2+n], caddr.String(), false)
-			defer func() {
-				pool.PutBuffer(reqBytes)
-				pool.PutBuffer(respBytes)
-			}()
+		go s.ServePacket(pc, caddr, reqBytes[:2+n])
+	}
+}
 
-			if err != nil {
-				log.F("[dns] error in exchange: %s", err)
-				return
-			}
+// ServePacket serves dns packet conn.
+func (s *Server) ServePacket(pc net.PacketConn, caddr net.Addr, reqBytes []byte) {
+	respBytes, err := s.Exchange(reqBytes, caddr.String(), false)
+	defer func() {
+		pool.PutBuffer(reqBytes)
+		pool.PutBuffer(respBytes)
+	}()
 
-			_, err = c.WriteTo(respBytes[2:], caddr)
-			if err != nil {
-				log.F("[dns] error in local write: %s", err)
-				return
-			}
-
-		}()
+	if err != nil {
+		log.F("[dns] error in exchange: %s", err)
+		return
 	}
 
+	_, err = pc.WriteTo(respBytes[2:], caddr)
+	if err != nil {
+		log.F("[dns] error in local write: %s", err)
+		return
+	}
 }
 
 // ListenAndServeTCP listen and serves on tcp port.
@@ -122,7 +123,7 @@ func (s *Server) ListenAndServeTCP(wg *sync.WaitGroup) {
 	}
 }
 
-// ServeTCP serves a tcp connection.
+// ServeTCP serves a dns tcp connection.
 func (s *Server) ServeTCP(c net.Conn) {
 	defer c.Close()
 
diff --git a/go.mod b/go.mod
index f0eb814..58250fb 100644
--- a/go.mod
+++ b/go.mod
@@ -10,8 +10,8 @@ require (
 	github.com/xtaci/kcp-go/v5 v5.5.15
 	golang.org/x/crypto v0.0.0-20200820211705-5c72a883971a
 	golang.org/x/net v0.0.0-20200822124328-c89045814202 // indirect
-	golang.org/x/sys v0.0.0-20200821140526-fda516888d29 // indirect
-	golang.org/x/tools v0.0.0-20200822203824-307de81be3f4 // indirect
+	golang.org/x/sys v0.0.0-20200824131525-c12d262b63d8 // indirect
+	golang.org/x/tools v0.0.0-20200823205832-c024452afbcd // indirect
 	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
 )
 
diff --git a/go.sum b/go.sum
index 112f3cf..693dbf1 100644
--- a/go.sum
+++ b/go.sum
@@ -117,15 +117,15 @@ golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200501145240-bc7a7d42d5c3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200808120158-1030fc2bf1d9 h1:yi1hN8dcqI9l8klZfy4B8mJvFmmAxJEePIQQFNSd7Cs=
 golang.org/x/sys v0.0.0-20200808120158-1030fc2bf1d9/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200821140526-fda516888d29 h1:mNuhGagCf3lDDm5C0376C/sxh6V7fy9WbdEu/YDNA04=
-golang.org/x/sys v0.0.0-20200821140526-fda516888d29/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200824131525-c12d262b63d8 h1:AvbQYmiaaaza3cW3QXRyPo5kYgpFIzOAfeAAN7m3qQ4=
+golang.org/x/sys v0.0.0-20200824131525-c12d262b63d8/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20200425043458-8463f397d07c h1:iHhCR0b26amDCiiO+kBguKZom9aMF+NrFxh9zeKR/XU=
 golang.org/x/tools v0.0.0-20200425043458-8463f397d07c/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
 golang.org/x/tools v0.0.0-20200808161706-5bf02b21f123/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
-golang.org/x/tools v0.0.0-20200822203824-307de81be3f4 h1:r0nbB2EeRbGpnVeqxlkgiBpNi/bednpSg78qzZGOuv0=
-golang.org/x/tools v0.0.0-20200822203824-307de81be3f4/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
+golang.org/x/tools v0.0.0-20200823205832-c024452afbcd h1:KNSumuk5eGuQV7zbOrDDZ3MIkwsQr0n5oKiH4oE0/hU=
+golang.org/x/tools v0.0.0-20200823205832-c024452afbcd/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
diff --git a/proxy/http/server.go b/proxy/http/server.go
index 1fd9ce9..0b2f703 100644
--- a/proxy/http/server.go
+++ b/proxy/http/server.go
@@ -102,11 +102,7 @@ func (s *HTTP) servHTTPS(r *request, c net.Conn) {
 
 	log.F("[http] %s <-> %s [c] via %s", c.RemoteAddr(), r.uri, dialer.Addr())
 
-	_, _, err = conn.Relay(c, rc)
-	if err != nil {
-		if err, ok := err.(net.Error); ok && err.Timeout() {
-			return // ignore i/o timeout
-		}
+	if err = conn.Relay(c, rc); err != nil {
 		log.F("[http] relay error: %v", err)
 		s.proxy.Record(dialer, false)
 	}
diff --git a/proxy/redir/redir_linux.go b/proxy/redir/redir_linux.go
index 227bf99..8dc0aea 100644
--- a/proxy/redir/redir_linux.go
+++ b/proxy/redir/redir_linux.go
@@ -113,11 +113,7 @@ func (s *RedirProxy) Serve(c net.Conn) {
 
 	log.F("[redir] %s <-> %s via %s", c.RemoteAddr(), tgt, dialer.Addr())
 
-	_, _, err = conn.Relay(c, rc)
-	if err != nil {
-		if err, ok := err.(net.Error); ok && err.Timeout() {
-			return // ignore i/o timeout
-		}
+	if err = conn.Relay(c, rc); err != nil {
 		log.F("[redir] relay error: %v", err)
 		s.proxy.Record(dialer, false)
 	}
diff --git a/proxy/socks5/socks5.go b/proxy/socks5/socks5.go
index 5354438..a018d45 100644
--- a/proxy/socks5/socks5.go
+++ b/proxy/socks5/socks5.go
@@ -141,11 +141,7 @@ func (s *Socks5) Serve(c net.Conn) {
 
 	log.F("[socks5] %s <-> %s via %s", c.RemoteAddr(), tgt, dialer.Addr())
 
-	_, _, err = conn.Relay(c, rc)
-	if err != nil {
-		if err, ok := err.(net.Error); ok && err.Timeout() {
-			return // ignore i/o timeout
-		}
+	if err = conn.Relay(c, rc); err != nil {
 		log.F("[socks5] relay error: %v", err)
 		s.proxy.Record(dialer, false)
 	}
diff --git a/proxy/ss/ss.go b/proxy/ss/ss.go
index 9f8a209..a6694f7 100644
--- a/proxy/ss/ss.go
+++ b/proxy/ss/ss.go
@@ -160,11 +160,7 @@ func (s *SS) Serve(c net.Conn) {
 
 	log.F("[ss] %s <-> %s via %s", c.RemoteAddr(), tgt, dialer.Addr())
 
-	_, _, err = conn.Relay(c, rc)
-	if err != nil {
-		if err, ok := err.(net.Error); ok && err.Timeout() {
-			return // ignore i/o timeout
-		}
+	if err = conn.Relay(c, rc); err != nil {
 		log.F("[ss] relay error: %v", err)
 		s.proxy.Record(dialer, false)
 	}
diff --git a/proxy/tcptun/tcptun.go b/proxy/tcptun/tcptun.go
index 3c87a64..4ade827 100644
--- a/proxy/tcptun/tcptun.go
+++ b/proxy/tcptun/tcptun.go
@@ -90,12 +90,8 @@ func (s *TCPTun) Serve(c net.Conn) {
 
 	log.F("[tcptun] %s <-> %s via %s", c.RemoteAddr(), s.raddr, dialer.Addr())
 
-	_, _, err = conn.Relay(c, rc)
-	if err != nil {
-		if err, ok := err.(net.Error); ok && err.Timeout() {
-			return // ignore i/o timeout
-		}
-		log.F("relay error: %v", err)
+	if err = conn.Relay(c, rc); err != nil {
+		log.F("[tcptun] relay error: %v", err)
 		s.proxy.Record(dialer, false)
 	}
 }
diff --git a/proxy/udptun/udptun.go b/proxy/udptun/udptun.go
index 0bee32a..9aef394 100644
--- a/proxy/udptun/udptun.go
+++ b/proxy/udptun/udptun.go
@@ -87,11 +87,11 @@ func (s *UDPTun) ListenAndServe() {
 
 			nm.Store(raddr.String(), pc)
 
-			go func() {
+			go func(c, pc net.PacketConn, raddr net.Addr) {
 				conn.RelayUDP(c, raddr, pc, 2*time.Minute)
 				pc.Close()
 				nm.Delete(raddr.String())
-			}()
+			}(c, pc, raddr)
 
 		} else {
 			pc = v.(net.PacketConn)
diff --git a/proxy/vmess/chunk.go b/proxy/vmess/chunk.go
index 828869b..0f6ec7a 100644
--- a/proxy/vmess/chunk.go
+++ b/proxy/vmess/chunk.go
@@ -25,8 +25,7 @@ func (w *chunkedWriter) Write(b []byte) (n int, err error) {
 	buf := pool.GetBuffer(lenSize + chunkSize)
 	defer pool.PutBuffer(buf)
 
-	left := len(b)
-	for left != 0 {
+	for left := len(b); left != 0; {
 		writeLen := left
 		if writeLen > chunkSize {
 			writeLen = chunkSize
@@ -49,6 +48,7 @@ func (w *chunkedWriter) Write(b []byte) (n int, err error) {
 
 type chunkedReader struct {
 	io.Reader
+	buf  [lenSize]byte
 	left int
 }
 
@@ -60,13 +60,11 @@ func ChunkedReader(r io.Reader) io.Reader {
 func (r *chunkedReader) Read(b []byte) (int, error) {
 	if r.left == 0 {
 		// get length
-		buf := pool.GetBuffer(lenSize)
-		_, err := io.ReadFull(r.Reader, buf[:lenSize])
+		_, err := io.ReadFull(r.Reader, r.buf[:lenSize])
 		if err != nil {
 			return 0, err
 		}
-		r.left = int(binary.BigEndian.Uint16(buf[:lenSize]))
-		pool.PutBuffer(buf)
+		r.left = int(binary.BigEndian.Uint16(r.buf[:lenSize]))
 
 		// if left == 0, then this is the end
 		if r.left == 0 {
diff --git a/proxy/ws/client.go b/proxy/ws/client.go
index cdb5013..3fe861b 100644
--- a/proxy/ws/client.go
+++ b/proxy/ws/client.go
@@ -93,7 +93,6 @@ func (c *Conn) Write(b []byte) (n int, err error) {
 	if c.writer == nil {
 		c.writer = FrameWriter(c.Conn)
 	}
-
 	return c.writer.Write(b)
 }
 
@@ -101,7 +100,6 @@ func (c *Conn) Read(b []byte) (n int, err error) {
 	if c.reader == nil {
 		c.reader = FrameReader(c.Conn)
 	}
-
 	return c.reader.Read(b)
 }
 
diff --git a/proxy/ws/frame.go b/proxy/ws/frame.go
index 7682cf8..e28cbc0 100644
--- a/proxy/ws/frame.go
+++ b/proxy/ws/frame.go
@@ -126,20 +126,17 @@ func (w *frameWriter) ReadFrom(r io.Reader) (n int64, err error) {
 
 type frameReader struct {
 	io.Reader
-	buf       []byte
-	leftBytes int64
+	buf  [8]byte
+	left int64
 }
 
 // FrameReader returns a chunked reader.
 func FrameReader(r io.Reader) io.Reader {
-	return &frameReader{
-		Reader: r,
-		buf:    make([]byte, maxFrameHeaderSize), // NOTE: buf only used to save header bytes now
-	}
+	return &frameReader{Reader: r}
 }
 
 func (r *frameReader) Read(b []byte) (int, error) {
-	if r.leftBytes == 0 {
+	if r.left == 0 {
 		// get msg header
 		_, err := io.ReadFull(r.Reader, r.buf[:2])
 		if err != nil {
@@ -149,26 +146,26 @@ func (r *frameReader) Read(b []byte) (int, error) {
 		// final := r.buf[0]&finalBit != 0
 		// frameType := int(r.buf[0] & 0xf)
 		// mask := r.buf[1]&maskBit != 0
-		r.leftBytes = int64(r.buf[1] & 0x7f)
-		switch r.leftBytes {
+		r.left = int64(r.buf[1] & 0x7f)
+		switch r.left {
 		case 126:
 			_, err := io.ReadFull(r.Reader, r.buf[:2])
 			if err != nil {
 				return 0, err
 			}
-			r.leftBytes = int64(binary.BigEndian.Uint16(r.buf[0:]))
+			r.left = int64(binary.BigEndian.Uint16(r.buf[:2]))
 		case 127:
 			_, err := io.ReadFull(r.Reader, r.buf[:8])
 			if err != nil {
 				return 0, err
 			}
-			r.leftBytes = int64(binary.BigEndian.Uint64(r.buf[0:]))
+			r.left = int64(binary.BigEndian.Uint64(r.buf[:8]))
 		}
 	}
 
 	readLen := int64(len(b))
-	if readLen > r.leftBytes {
-		readLen = r.leftBytes
+	if readLen > r.left {
+		readLen = r.left
 	}
 
 	m, err := r.Reader.Read(b[:readLen])
@@ -176,6 +173,6 @@ func (r *frameReader) Read(b []byte) (int, error) {
 		return 0, err
 	}
 
-	r.leftBytes -= int64(m)
+	r.left -= int64(m)
 	return m, err
 }