From 7026afdd7734bb4d4e7ec1e765f0c83da53dc69b Mon Sep 17 00:00:00 2001
From: xjasonlyu <xjasonlyu@gmail.com>
Date: Sat, 31 Aug 2024 16:46:49 -0400
Subject: [PATCH] aaa

pool

pool

buffer

ppp

buffer

up
---
 {internal/pool => buffer/allocator}/alloc.go  | 28 +++---
 .../pool => buffer/allocator}/alloc_test.go   |  8 +-
 buffer/pool.go                                | 29 +++++++
 internal/pool/buffer.go                       | 17 ----
 internal/pool/pool.go                         | 47 ++++++----
 internal/pool/pool_test.go                    | 85 +++++++++++++++++++
 proxy/relay.go                                |  6 +-
 transport/internal/bufferpool/bufferpool.go   | 25 ++++++
 transport/shadowsocks/shadowaead/packet.go    |  6 +-
 transport/shadowsocks/shadowaead/stream.go    | 18 ++--
 transport/shadowsocks/shadowstream/packet.go  |  6 +-
 transport/simple-obfs/http.go                 | 12 +--
 transport/simple-obfs/tls.go                  | 15 ++--
 transport/socks4/socks4.go                    |  8 +-
 transport/socks5/socks5.go                    | 17 +++-
 tunnel/tcp.go                                 |  6 +-
 tunnel/udp.go                                 |  6 +-
 17 files changed, 243 insertions(+), 96 deletions(-)
 rename {internal/pool => buffer/allocator}/alloc.go (64%)
 rename {internal/pool => buffer/allocator}/alloc_test.go (93%)
 create mode 100644 buffer/pool.go
 delete mode 100644 internal/pool/buffer.go
 create mode 100644 internal/pool/pool_test.go
 create mode 100644 transport/internal/bufferpool/bufferpool.go

diff --git a/internal/pool/alloc.go b/buffer/allocator/alloc.go
similarity index 64%
rename from internal/pool/alloc.go
rename to buffer/allocator/alloc.go
index 9a4cc106..ea12ac98 100644
--- a/internal/pool/alloc.go
+++ b/buffer/allocator/alloc.go
@@ -1,30 +1,29 @@
-package pool
+package allocator
 
 import (
 	"errors"
 	"math/bits"
-	"sync"
-)
 
-var _allocator = NewAllocator()
+	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
+)
 
 // Allocator for incoming frames, optimized to prevent overwriting
 // after zeroing.
 type Allocator struct {
-	buffers []sync.Pool
+	buffers []*pool.Pool[[]byte]
 }
 
-// NewAllocator initiates a []byte allocator for frames less than
-// 65536 bytes, the waste(memory fragmentation) of space allocation
-// is guaranteed to be no more than 50%.
-func NewAllocator() *Allocator {
+// New initiates a []byte allocator for frames less than 65536 bytes,
+// the waste(memory fragmentation) of space allocation is guaranteed
+// to be no more than 50%.
+func New() *Allocator {
 	alloc := &Allocator{}
-	alloc.buffers = make([]sync.Pool, 17) // 1B -> 64K
+	alloc.buffers = make([]*pool.Pool[[]byte], 17) // 1B -> 64K
 	for k := range alloc.buffers {
 		i := k
-		alloc.buffers[k].New = func() any {
+		alloc.buffers[k] = pool.New(func() []byte {
 			return make([]byte, 1<<uint32(i))
-		}
+		})
 	}
 	return alloc
 }
@@ -37,10 +36,10 @@ func (alloc *Allocator) Get(size int) []byte {
 
 	b := msb(size)
 	if size == 1<<b {
-		return alloc.buffers[b].Get().([]byte)[:size]
+		return alloc.buffers[b].Get()[:size]
 	}
 
-	return alloc.buffers[b+1].Get().([]byte)[:size]
+	return alloc.buffers[b+1].Get()[:size]
 }
 
 // Put returns a []byte to pool for future use,
@@ -51,7 +50,6 @@ func (alloc *Allocator) Put(buf []byte) error {
 		return errors.New("allocator Put() incorrect buffer size")
 	}
 
-	//nolint:staticcheck
 	alloc.buffers[b].Put(buf)
 	return nil
 }
diff --git a/internal/pool/alloc_test.go b/buffer/allocator/alloc_test.go
similarity index 93%
rename from internal/pool/alloc_test.go
rename to buffer/allocator/alloc_test.go
index 429b7c40..f4926029 100644
--- a/internal/pool/alloc_test.go
+++ b/buffer/allocator/alloc_test.go
@@ -1,4 +1,4 @@
-package pool
+package allocator
 
 import (
 	"math/rand"
@@ -8,7 +8,7 @@ import (
 )
 
 func TestAllocGet(t *testing.T) {
-	alloc := NewAllocator()
+	alloc := New()
 	assert.Nil(t, alloc.Get(0))
 	assert.Equal(t, 1, len(alloc.Get(1)))
 	assert.Equal(t, 2, len(alloc.Get(2)))
@@ -23,7 +23,7 @@ func TestAllocGet(t *testing.T) {
 }
 
 func TestAllocPut(t *testing.T) {
-	alloc := NewAllocator()
+	alloc := New()
 	assert.NotNil(t, alloc.Put(nil), "put nil misbehavior")
 	assert.NotNil(t, alloc.Put(make([]byte, 3)), "put elem:3 []bytes misbehavior")
 	assert.Nil(t, alloc.Put(make([]byte, 4)), "put elem:4 []bytes misbehavior")
@@ -33,7 +33,7 @@ func TestAllocPut(t *testing.T) {
 }
 
 func TestAllocPutThenGet(t *testing.T) {
-	alloc := NewAllocator()
+	alloc := New()
 	data := alloc.Get(4)
 	_ = alloc.Put(data)
 	newData := alloc.Get(4)
diff --git a/buffer/pool.go b/buffer/pool.go
new file mode 100644
index 00000000..0b243d72
--- /dev/null
+++ b/buffer/pool.go
@@ -0,0 +1,29 @@
+// Package buffer provides a pool of []byte.
+package buffer
+
+import (
+	"github.com/xjasonlyu/tun2socks/v2/buffer/allocator"
+)
+
+const (
+	// MaxSegmentSize is the largest possible UDP datagram size.
+	MaxSegmentSize = (1 << 16) - 1
+
+	// RelayBufferSize is a buffer of 20 KiB to reduce the memory
+	// of each TCP relay as io.Copy default buffer size is 32 KiB,
+	// but the maximum packet size of vmess/shadowsocks is about
+	// 16 KiB, so define .
+	RelayBufferSize = 20 << 10
+)
+
+var _allocator = allocator.New()
+
+// Get gets a []byte from default allocator with most appropriate cap.
+func Get(size int) []byte {
+	return _allocator.Get(size)
+}
+
+// Put returns a []byte to default allocator for future use.
+func Put(buf []byte) error {
+	return _allocator.Put(buf)
+}
diff --git a/internal/pool/buffer.go b/internal/pool/buffer.go
deleted file mode 100644
index 9762b087..00000000
--- a/internal/pool/buffer.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package pool
-
-import (
-	"bytes"
-	"sync"
-)
-
-var _bufferPool = sync.Pool{New: func() any { return &bytes.Buffer{} }}
-
-func GetBuffer() *bytes.Buffer {
-	return _bufferPool.Get().(*bytes.Buffer)
-}
-
-func PutBuffer(buf *bytes.Buffer) {
-	buf.Reset()
-	_bufferPool.Put(buf)
-}
diff --git a/internal/pool/pool.go b/internal/pool/pool.go
index b85e4440..e05ff6ef 100644
--- a/internal/pool/pool.go
+++ b/internal/pool/pool.go
@@ -1,23 +1,38 @@
-// Package pool provides a pool of []byte.
+// Package pool provides internal pool utilities.
 package pool
 
-const (
-	// MaxSegmentSize is the largest possible UDP datagram size.
-	MaxSegmentSize = (1 << 16) - 1
-
-	// RelayBufferSize is a buffer of 20 KiB to reduce the memory
-	// of each TCP relay as io.Copy default buffer size is 32 KiB,
-	// but the maximum packet size of vmess/shadowsocks is about
-	// 16 KiB, so define .
-	RelayBufferSize = 20 << 10
+import (
+	"sync"
 )
 
-// Get gets a []byte from default allocator with most appropriate cap.
-func Get(size int) []byte {
-	return _allocator.Get(size)
+// A Pool is a generic wrapper around [sync.Pool] to provide strongly-typed
+// object pooling.
+//
+// Note that SA6002 (ref: https://staticcheck.io/docs/checks/#SA6002) will
+// not be detected, so all internal pool use must take care to only store
+// pointer types.
+type Pool[T any] struct {
+	pool sync.Pool
+}
+
+// New returns a new [Pool] for T, and will use fn to construct new Ts when
+// the pool is empty.
+func New[T any](fn func() T) *Pool[T] {
+	return &Pool[T]{
+		pool: sync.Pool{
+			New: func() any {
+				return fn()
+			},
+		},
+	}
+}
+
+// Get gets a T from the pool, or creates a new one if the pool is empty.
+func (p *Pool[T]) Get() T {
+	return p.pool.Get().(T)
 }
 
-// Put returns a []byte to default allocator for future use.
-func Put(buf []byte) error {
-	return _allocator.Put(buf)
+// Put returns x into the pool.
+func (p *Pool[T]) Put(x T) {
+	p.pool.Put(x)
 }
diff --git a/internal/pool/pool_test.go b/internal/pool/pool_test.go
new file mode 100644
index 00000000..4a6c4a18
--- /dev/null
+++ b/internal/pool/pool_test.go
@@ -0,0 +1,85 @@
+package pool
+
+import (
+	"runtime/debug"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+type pooledValue[T any] struct {
+	value T
+}
+
+func TestNew(t *testing.T) {
+	// Disable GC to avoid the victim cache during the test.
+	defer debug.SetGCPercent(debug.SetGCPercent(-1))
+
+	p := New(func() *pooledValue[string] {
+		return &pooledValue[string]{
+			value: "new",
+		}
+	})
+
+	// Probabilistically, 75% of sync.Pool.Put calls will succeed when -race
+	// is enabled (see ref below); attempt to make this quasi-deterministic by
+	// brute force (i.e., put significantly more objects in the pool than we
+	// will need for the test) in order to avoid testing without race enabled.
+	//
+	// ref: https://cs.opensource.google/go/go/+/refs/tags/go1.20.2:src/sync/pool.go;l=100-103
+	for i := 0; i < 1_000; i++ {
+		p.Put(&pooledValue[string]{
+			value: t.Name(),
+		})
+	}
+
+	// Ensure that we always get the expected value. Note that this must only
+	// run a fraction of the number of times that Put is called above.
+	for i := 0; i < 10; i++ {
+		func() {
+			x := p.Get()
+			defer p.Put(x)
+			require.Equal(t, t.Name(), x.value)
+		}()
+	}
+
+	// Depool all objects that might be in the pool to ensure that it's empty.
+	for i := 0; i < 1_000; i++ {
+		p.Get()
+	}
+
+	// Now that the pool is empty, it should use the value specified in the
+	// underlying sync.Pool.New func.
+	require.Equal(t, "new", p.Get().value)
+}
+
+func TestNew_Race(t *testing.T) {
+	p := New(func() *pooledValue[int] {
+		return &pooledValue[int]{
+			value: -1,
+		}
+	})
+
+	var wg sync.WaitGroup
+	defer wg.Wait()
+
+	// Run a number of goroutines that read and write pool object fields to
+	// tease out races.
+	for i := 0; i < 1_000; i++ {
+		i := i
+
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+
+			x := p.Get()
+			defer p.Put(x)
+
+			// Must both read and write the field.
+			if n := x.value; n >= -1 {
+				x.value = i
+			}
+		}()
+	}
+}
diff --git a/proxy/relay.go b/proxy/relay.go
index 87343e7a..7dadc975 100644
--- a/proxy/relay.go
+++ b/proxy/relay.go
@@ -13,8 +13,8 @@ import (
 
 	"github.com/go-gost/relay"
 
+	"github.com/xjasonlyu/tun2socks/v2/buffer"
 	"github.com/xjasonlyu/tun2socks/v2/dialer"
-	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
 	M "github.com/xjasonlyu/tun2socks/v2/metadata"
 	"github.com/xjasonlyu/tun2socks/v2/proxy/proto"
 )
@@ -169,8 +169,8 @@ func (rc *relayConn) Read(b []byte) (n int, err error) {
 		return io.ReadFull(rc.Conn, b[:dLen])
 	}
 
-	buf := pool.Get(dLen)
-	defer pool.Put(buf)
+	buf := buffer.Get(dLen)
+	defer buffer.Put(buf)
 	_, err = io.ReadFull(rc.Conn, buf)
 	n = copy(b, buf)
 
diff --git a/transport/internal/bufferpool/bufferpool.go b/transport/internal/bufferpool/bufferpool.go
new file mode 100644
index 00000000..170ca9d3
--- /dev/null
+++ b/transport/internal/bufferpool/bufferpool.go
@@ -0,0 +1,25 @@
+package bufferpool
+
+import (
+	"bytes"
+
+	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
+)
+
+const _size = 1024 // by default, create 1 KiB buffers
+
+var _pool = pool.New(func() *bytes.Buffer {
+	buf := &bytes.Buffer{}
+	buf.Grow(_size)
+	return buf
+})
+
+func Get() *bytes.Buffer {
+	buf := _pool.Get()
+	buf.Reset()
+	return buf
+}
+
+func Put(b *bytes.Buffer) {
+	_pool.Put(b)
+}
diff --git a/transport/shadowsocks/shadowaead/packet.go b/transport/shadowsocks/shadowaead/packet.go
index 91b0bf4c..25fb1dc6 100755
--- a/transport/shadowsocks/shadowaead/packet.go
+++ b/transport/shadowsocks/shadowaead/packet.go
@@ -6,7 +6,7 @@ import (
 	"io"
 	"net"
 
-	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
+	"github.com/xjasonlyu/tun2socks/v2/buffer"
 )
 
 // ErrShortPacket means that the packet is too short for a valid encrypted packet.
@@ -70,8 +70,8 @@ func NewPacketConn(c net.PacketConn, ciph Cipher) *PacketConn {
 
 // WriteTo encrypts b and write to addr using the embedded PacketConn.
 func (c *PacketConn) WriteTo(b []byte, addr net.Addr) (int, error) {
-	buf := pool.Get(maxPacketSize)
-	defer pool.Put(buf)
+	buf := buffer.Get(maxPacketSize)
+	defer buffer.Put(buf)
 	buf, err := Pack(buf, b, c)
 	if err != nil {
 		return 0, err
diff --git a/transport/shadowsocks/shadowaead/stream.go b/transport/shadowsocks/shadowaead/stream.go
index 83cc6410..3a13ba55 100755
--- a/transport/shadowsocks/shadowaead/stream.go
+++ b/transport/shadowsocks/shadowaead/stream.go
@@ -7,7 +7,7 @@ import (
 	"io"
 	"net"
 
-	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
+	"github.com/xjasonlyu/tun2socks/v2/buffer"
 )
 
 const (
@@ -29,8 +29,8 @@ func NewWriter(w io.Writer, aead cipher.AEAD) *Writer { return &Writer{Writer: w
 
 // Write encrypts p and writes to the embedded io.Writer.
 func (w *Writer) Write(p []byte) (n int, err error) {
-	buf := pool.Get(bufSize)
-	defer pool.Put(buf)
+	buf := buffer.Get(bufSize)
+	defer buffer.Put(buf)
 	nonce := w.nonce[:w.NonceSize()]
 	tag := w.Overhead()
 	off := 2 + tag
@@ -65,8 +65,8 @@ func (w *Writer) Write(p []byte) (n int, err error) {
 // writes to the embedded io.Writer. Returns number of bytes read from r and
 // any error encountered.
 func (w *Writer) ReadFrom(r io.Reader) (n int64, err error) {
-	buf := pool.Get(bufSize)
-	defer pool.Put(buf)
+	buf := buffer.Get(bufSize)
+	defer buffer.Put(buf)
 	nonce := w.nonce[:w.NonceSize()]
 	tag := w.Overhead()
 	off := 2 + tag
@@ -142,7 +142,7 @@ func (r *Reader) Read(p []byte) (int, error) {
 		if len(p) >= payloadSizeMask+r.Overhead() {
 			return r.read(p)
 		}
-		b := pool.Get(bufSize)
+		b := buffer.Get(bufSize)
 		n, err := r.read(b)
 		if err != nil {
 			return 0, err
@@ -154,7 +154,7 @@ func (r *Reader) Read(p []byte) (int, error) {
 	n := copy(p, r.buf[r.off:])
 	r.off += n
 	if r.off == len(r.buf) {
-		pool.Put(r.buf[:cap(r.buf)])
+		buffer.Put(r.buf[:cap(r.buf)])
 		r.buf = nil
 	}
 	return n, nil
@@ -165,7 +165,7 @@ func (r *Reader) Read(p []byte) (int, error) {
 // bytes written to w and any error encountered.
 func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
 	if r.buf == nil {
-		r.buf = pool.Get(bufSize)
+		r.buf = buffer.Get(bufSize)
 		r.off = len(r.buf)
 	}
 
@@ -176,7 +176,7 @@ func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
 			n += int64(nw)
 			if ew != nil {
 				if r.off == len(r.buf) {
-					pool.Put(r.buf[:cap(r.buf)])
+					buffer.Put(r.buf[:cap(r.buf)])
 					r.buf = nil
 				}
 				err = ew
diff --git a/transport/shadowsocks/shadowstream/packet.go b/transport/shadowsocks/shadowstream/packet.go
index 082a6d59..732474f9 100755
--- a/transport/shadowsocks/shadowstream/packet.go
+++ b/transport/shadowsocks/shadowstream/packet.go
@@ -6,7 +6,7 @@ import (
 	"io"
 	"net"
 
-	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
+	"github.com/xjasonlyu/tun2socks/v2/buffer"
 )
 
 // ErrShortPacket means the packet is too short to be a valid encrypted packet.
@@ -55,8 +55,8 @@ func NewPacketConn(c net.PacketConn, ciph Cipher) *PacketConn {
 const maxPacketSize = 64 * 1024
 
 func (c *PacketConn) WriteTo(b []byte, addr net.Addr) (int, error) {
-	buf := pool.Get(maxPacketSize)
-	defer pool.Put(buf)
+	buf := buffer.Get(maxPacketSize)
+	defer buffer.Put(buf)
 	buf, err := Pack(buf, b, c.Cipher)
 	if err != nil {
 		return 0, err
diff --git a/transport/simple-obfs/http.go b/transport/simple-obfs/http.go
index bdae1a35..9c71d78b 100644
--- a/transport/simple-obfs/http.go
+++ b/transport/simple-obfs/http.go
@@ -10,7 +10,7 @@ import (
 	"net"
 	"net/http"
 
-	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
+	"github.com/xjasonlyu/tun2socks/v2/buffer"
 )
 
 // HTTPObfs is shadowsocks http simple-obfs implementation
@@ -29,22 +29,22 @@ func (ho *HTTPObfs) Read(b []byte) (int, error) {
 		n := copy(b, ho.buf[ho.offset:])
 		ho.offset += n
 		if ho.offset == len(ho.buf) {
-			pool.Put(ho.buf)
+			buffer.Put(ho.buf)
 			ho.buf = nil
 		}
 		return n, nil
 	}
 
 	if ho.firstResponse {
-		buf := pool.Get(pool.RelayBufferSize)
+		buf := buffer.Get(buffer.RelayBufferSize)
 		n, err := ho.Conn.Read(buf)
 		if err != nil {
-			pool.Put(buf)
+			buffer.Put(buf)
 			return 0, err
 		}
 		idx := bytes.Index(buf[:n], []byte("\r\n\r\n"))
 		if idx == -1 {
-			pool.Put(buf)
+			buffer.Put(buf)
 			return 0, io.EOF
 		}
 		ho.firstResponse = false
@@ -54,7 +54,7 @@ func (ho *HTTPObfs) Read(b []byte) (int, error) {
 			ho.buf = buf[:idx+4+length]
 			ho.offset = idx + 4 + n
 		} else {
-			pool.Put(buf)
+			buffer.Put(buf)
 		}
 		return n, nil
 	}
diff --git a/transport/simple-obfs/tls.go b/transport/simple-obfs/tls.go
index a9a39263..e91e6bc4 100644
--- a/transport/simple-obfs/tls.go
+++ b/transport/simple-obfs/tls.go
@@ -1,14 +1,14 @@
 package obfs
 
 import (
-	"bytes"
 	"crypto/rand"
 	"encoding/binary"
 	"io"
 	"net"
 	"time"
 
-	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
+	"github.com/xjasonlyu/tun2socks/v2/buffer"
+	"github.com/xjasonlyu/tun2socks/v2/transport/internal/bufferpool"
 )
 
 const (
@@ -25,12 +25,12 @@ type TLSObfs struct {
 }
 
 func (to *TLSObfs) read(b []byte, discardN int) (int, error) {
-	buf := pool.Get(discardN)
+	buf := buffer.Get(discardN)
 	_, err := io.ReadFull(to.Conn, buf)
 	if err != nil {
 		return 0, err
 	}
-	pool.Put(buf)
+	buffer.Put(buf)
 
 	sizeBuf := make([]byte, 2)
 	_, err = io.ReadFull(to.Conn, sizeBuf)
@@ -99,8 +99,8 @@ func (to *TLSObfs) write(b []byte) (int, error) {
 		return len(b), err
 	}
 
-	buf := pool.GetBuffer()
-	defer pool.PutBuffer(buf)
+	buf := bufferpool.Get()
+	defer bufferpool.Put(buf)
 	buf.Write([]byte{0x17, 0x03, 0x03})
 	binary.Write(buf, binary.BigEndian, uint16(len(b)))
 	buf.Write(b)
@@ -124,7 +124,8 @@ func makeClientHelloMsg(data []byte, server string) []byte {
 	rand.Read(random)
 	rand.Read(sessionID)
 
-	buf := &bytes.Buffer{}
+	buf := bufferpool.Get()
+	defer bufferpool.Put(buf)
 
 	// handshake, TLS 1.0 version, length
 	buf.WriteByte(22)
diff --git a/transport/socks4/socks4.go b/transport/socks4/socks4.go
index 514f2d54..e096da14 100644
--- a/transport/socks4/socks4.go
+++ b/transport/socks4/socks4.go
@@ -2,13 +2,14 @@
 package socks4
 
 import (
-	"bytes"
 	"encoding/binary"
 	"errors"
 	"io"
 	"net"
 	"net/netip"
 	"strconv"
+
+	"github.com/xjasonlyu/tun2socks/v2/transport/internal/bufferpool"
 )
 
 const Version = 0x04
@@ -64,13 +65,14 @@ func ClientHandshake(rw io.ReadWriter, addr string, command Command, userID stri
 		return errIPv6NotSupported
 	}
 
-	req := &bytes.Buffer{}
+	req := bufferpool.Get()
+	defer bufferpool.Put(req)
 	req.WriteByte(Version)
 	req.WriteByte(command)
 	_ = binary.Write(req, binary.BigEndian, port)
 	req.Write(ip.AsSlice())
 	req.WriteString(userID)
-	req.WriteByte(0) /* NULL */
+	req.WriteByte(0x00) /* NULL */
 
 	if isReservedIP(ip) /* SOCKS4A */ {
 		req.WriteString(host)
diff --git a/transport/socks5/socks5.go b/transport/socks5/socks5.go
index 43bab41d..f8acbf69 100644
--- a/transport/socks5/socks5.go
+++ b/transport/socks5/socks5.go
@@ -10,6 +10,8 @@ import (
 	"net"
 	"net/netip"
 	"strconv"
+
+	"github.com/xjasonlyu/tun2socks/v2/transport/internal/bufferpool"
 )
 
 // AuthMethod is the authentication method as defined in RFC 1928 section 3.
@@ -206,10 +208,9 @@ func ClientHandshake(rw io.ReadWriter, addr Addr, command Command, user *User) (
 			return nil, errors.New("auth username/password too long")
 		}
 
-		authMsgLen := 1 + 1 + uLen + 1 + pLen
-
 		// password protocol version
-		authMsg := bytes.NewBuffer(make([]byte, 0, authMsgLen))
+		authMsg := bufferpool.Get()
+		defer bufferpool.Put(authMsg)
 		authMsg.WriteByte(0x01 /* VER */)
 		authMsg.WriteByte(byte(uLen) /* ULEN */)
 		authMsg.WriteString(user.Username /* UNAME */)
@@ -233,7 +234,15 @@ func ClientHandshake(rw io.ReadWriter, addr Addr, command Command, user *User) (
 	}
 
 	// VER, CMD, RSV, ADDR
-	if _, err := rw.Write(bytes.Join([][]byte{{Version, byte(command), 0x00 /* RSV */}, addr}, nil)); err != nil {
+	req := bufferpool.Get()
+	defer bufferpool.Put(req)
+	req.Grow(3 + MaxAddrLen)
+	req.WriteByte(Version)
+	req.WriteByte(byte(command))
+	req.WriteByte(0x00 /* RSV */)
+	req.Write(addr)
+
+	if _, err := rw.Write(req.Bytes()); err != nil {
 		return nil, err
 	}
 
diff --git a/tunnel/tcp.go b/tunnel/tcp.go
index 6ac563dc..be7b4fc6 100644
--- a/tunnel/tcp.go
+++ b/tunnel/tcp.go
@@ -7,8 +7,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/xjasonlyu/tun2socks/v2/buffer"
 	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
-	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
 	"github.com/xjasonlyu/tun2socks/v2/log"
 	M "github.com/xjasonlyu/tun2socks/v2/metadata"
 	"github.com/xjasonlyu/tun2socks/v2/tunnel/statistic"
@@ -56,11 +56,11 @@ func pipe(origin, remote net.Conn) {
 
 func unidirectionalStream(dst, src net.Conn, dir string, wg *sync.WaitGroup) {
 	defer wg.Done()
-	buf := pool.Get(pool.RelayBufferSize)
+	buf := buffer.Get(buffer.RelayBufferSize)
 	if _, err := io.CopyBuffer(dst, src, buf); err != nil {
 		log.Debugf("[TCP] copy data for %s: %v", dir, err)
 	}
-	pool.Put(buf)
+	buffer.Put(buf)
 	// Do the upload/download side TCP half-close.
 	if cr, ok := src.(interface{ CloseRead() error }); ok {
 		cr.CloseRead()
diff --git a/tunnel/udp.go b/tunnel/udp.go
index 03c5e3eb..87973862 100644
--- a/tunnel/udp.go
+++ b/tunnel/udp.go
@@ -6,8 +6,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/xjasonlyu/tun2socks/v2/buffer"
 	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
-	"github.com/xjasonlyu/tun2socks/v2/internal/pool"
 	"github.com/xjasonlyu/tun2socks/v2/log"
 	M "github.com/xjasonlyu/tun2socks/v2/metadata"
 	"github.com/xjasonlyu/tun2socks/v2/tunnel/statistic"
@@ -66,8 +66,8 @@ func unidirectionalPacketStream(dst, src net.PacketConn, to net.Addr, dir string
 }
 
 func copyPacketData(dst, src net.PacketConn, to net.Addr, timeout time.Duration) error {
-	buf := pool.Get(pool.MaxSegmentSize)
-	defer pool.Put(buf)
+	buf := buffer.Get(buffer.MaxSegmentSize)
+	defer buffer.Put(buf)
 
 	for {
 		src.SetReadDeadline(time.Now().Add(timeout))