diff --git a/common/buf/buffer.go b/common/buf/buffer.go
index 4306d05..6bcde17 100644
--- a/common/buf/buffer.go
+++ b/common/buf/buffer.go
@@ -2,7 +2,6 @@ package buf
 
 import (
 	"crypto/rand"
-	"fmt"
 	"io"
 	"net"
 	"strconv"
@@ -258,10 +257,6 @@ func (b *Buffer) WriteString(s string) (int, error) {
 	return b.Write([]byte(s))
 }
 
-func (b *Buffer) WriteSprint(s ...any) (int, error) {
-	return b.WriteString(fmt.Sprint(s...))
-}
-
 func (b *Buffer) WriteZero() error {
 	if b.IsFull() {
 		return io.ErrShortBuffer
diff --git a/common/cache/lrucache.go b/common/cache/lrucache.go
index edbe403..e3e1cf2 100644
--- a/common/cache/lrucache.go
+++ b/common/cache/lrucache.go
@@ -6,7 +6,7 @@ import (
 	"sync"
 	"time"
 
-	"github.com/sagernet/sing/common/list"
+	"github.com/sagernet/sing/common/x/list"
 )
 
 type Option[K comparable, V any] func(*LruCache[K, V])
diff --git a/common/exceptions/error.go b/common/exceptions/error.go
index 5450b9f..8527b16 100644
--- a/common/exceptions/error.go
+++ b/common/exceptions/error.go
@@ -3,10 +3,11 @@ package exceptions
 import (
 	"context"
 	"errors"
-	"fmt"
 	"io"
 	"net"
 	"os"
+
+	F "github.com/sagernet/sing/common/format"
 )
 
 type causeError struct {
@@ -42,15 +43,15 @@ func (e *extendedError) Unwrap() error {
 }
 
 func New(message ...any) error {
-	return errors.New(fmt.Sprint(message...))
+	return errors.New(F.ToString(message...))
 }
 
 func Cause(cause error, message ...any) error {
-	return &causeError{fmt.Sprint(message...), cause}
+	return &causeError{F.ToString(message...), cause}
 }
 
 func Extend(cause error, message ...any) error {
-	return &extendedError{fmt.Sprint(message...), cause}
+	return &extendedError{F.ToString(message...), cause}
 }
 
 type HasInnerError interface {
diff --git a/common/format/fmt.go b/common/format/fmt.go
new file mode 100644
index 0000000..dfd8976
--- /dev/null
+++ b/common/format/fmt.go
@@ -0,0 +1,54 @@
+package format
+
+import (
+	"strconv"
+)
+
+type Stringer interface {
+	String() string
+}
+
+func ToString(messages ...any) string {
+	var output string
+	for _, rawMessage := range messages {
+		if rawMessage == nil {
+			output += "nil"
+			continue
+		}
+		switch message := rawMessage.(type) {
+		case string:
+			output += message
+		case bool:
+			if message {
+				output += "true"
+			} else {
+				output += "false"
+			}
+		case uint8:
+			output += strconv.FormatUint(uint64(message), 10)
+		case uint16:
+			output += strconv.FormatUint(uint64(message), 10)
+		case uint32:
+			output += strconv.FormatUint(uint64(message), 10)
+		case uint64:
+			output += strconv.FormatUint(message, 10)
+		case int8:
+			output += strconv.FormatInt(int64(message), 10)
+		case int16:
+			output += strconv.FormatInt(int64(message), 10)
+		case int32:
+			output += strconv.FormatInt(int64(message), 10)
+		case int64:
+			output += strconv.FormatInt(message, 10)
+		case uintptr:
+			output += strconv.FormatUint(uint64(message), 10)
+		case error:
+			output += message.Error()
+		case Stringer:
+			output += message.String()
+		default:
+			panic("unknown value")
+		}
+	}
+	return output
+}
diff --git a/common/net.go b/common/net.go
index d454713..a8e4135 100644
--- a/common/net.go
+++ b/common/net.go
@@ -1,17 +1,9 @@
 package common
 
 import (
-	"os"
 	"syscall"
 )
 
-func TryFileDescriptor(conn any) (uintptr, error) {
-	if rawConn, isRaw := conn.(syscall.Conn); isRaw {
-		return GetFileDescriptor(rawConn)
-	}
-	return 0, os.ErrInvalid
-}
-
 func GetFileDescriptor(conn syscall.Conn) (uintptr, error) {
 	rawConn, err := conn.SyscallConn()
 	if err != nil {
diff --git a/common/network/http.go b/common/network/http.go
deleted file mode 100644
index fa908fe..0000000
--- a/common/network/http.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package network
-
-import (
-	"context"
-	"io/ioutil"
-	"net"
-	"net/http"
-)
-
-func HTTPClientWithNetwork(network string) *http.Client {
-	return &http.Client{
-		Transport: &http.Transport{
-			DialContext: func(ctx context.Context, _, addr string) (net.Conn, error) {
-				var dialer net.Dialer
-				return dialer.DialContext(ctx, network, addr)
-			},
-		},
-	}
-}
-
-func Get(url string) ([]byte, error) {
-	response, err := http.Get(url)
-	if err != nil {
-		return nil, err
-	}
-	defer response.Body.Close()
-	return ioutil.ReadAll(response.Body)
-}
-
-func GetContext(ctx context.Context, client *http.Client, url string) ([]byte, error) {
-	request, err := http.NewRequestWithContext(ctx, "GET", url, nil)
-	if err != nil {
-		return nil, err
-	}
-	response, err := client.Do(request)
-	if err != nil {
-		return nil, err
-	}
-	defer response.Body.Close()
-	return ioutil.ReadAll(response.Body)
-}
diff --git a/common/network/pem.go b/common/network/pem.go
deleted file mode 100644
index c8accd7..0000000
--- a/common/network/pem.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package network
-
-import (
-	"crypto/ecdsa"
-	"crypto/rsa"
-	"crypto/x509"
-	"encoding/pem"
-)
-
-func PEMBlock(data interface{}) *pem.Block {
-	var pemBlock *pem.Block
-	switch key := data.(type) {
-	case *ecdsa.PrivateKey:
-		keyBytes, _ := x509.MarshalECPrivateKey(key)
-		pemBlock = &pem.Block{Type: "EC PRIVATE KEY", Bytes: keyBytes}
-	case *rsa.PrivateKey:
-		pemBlock = &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(key)}
-	case *x509.CertificateRequest:
-		pemBlock = &pem.Block{Type: "CERTIFICATE REQUEST", Bytes: key.Raw}
-	}
-
-	return pemBlock
-}
diff --git a/common/os.go b/common/os.go
deleted file mode 100644
index 4e8771a..0000000
--- a/common/os.go
+++ /dev/null
@@ -1,52 +0,0 @@
-package common
-
-import (
-	"encoding/json"
-	"io/ioutil"
-	"os"
-	"strings"
-)
-
-func FileExists(path string) bool {
-	return Error(os.Stat(path)) == nil
-}
-
-func WriteFile(path string, content []byte) error {
-	if strings.Contains(path, "/") {
-		parent := path[:strings.LastIndex(path, "/")]
-		if !FileExists(parent) {
-			err := os.MkdirAll(parent, 0o755)
-			if err != nil {
-				return err
-			}
-		}
-	}
-
-	file, err := os.Create(path)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-	_, err = file.Write(content)
-	return err
-}
-
-func ReadJSON(path string, data any) error {
-	content, err := ioutil.ReadFile(path)
-	if err != nil {
-		return err
-	}
-	err = json.Unmarshal(content, data)
-	if err != nil {
-		return err
-	}
-	return nil
-}
-
-func WriteJSON(path string, data any) error {
-	content, err := json.Marshal(data)
-	if err != nil {
-		return err
-	}
-	return WriteFile(path, content)
-}
diff --git a/common/redir/tproxy_linux.go b/common/redir/tproxy_linux.go
index 3c310c3..0984332 100644
--- a/common/redir/tproxy_linux.go
+++ b/common/redir/tproxy_linux.go
@@ -2,7 +2,6 @@ package redir
 
 import (
 	"encoding/binary"
-	"fmt"
 	"net"
 	"net/netip"
 	"os"
@@ -10,6 +9,7 @@ import (
 	"syscall"
 
 	E "github.com/sagernet/sing/common/exceptions"
+	F "github.com/sagernet/sing/common/format"
 	M "github.com/sagernet/sing/common/metadata"
 	"golang.org/x/sys/unix"
 )
@@ -88,7 +88,7 @@ func DialUDP(network string, lAddr *net.UDPAddr, rAddr *net.UDPAddr) (*net.UDPCo
 		return nil, err
 	}
 
-	fdFile := os.NewFile(uintptr(fd), fmt.Sprintf("net-udp-dial-%s", rAddr.String()))
+	fdFile := os.NewFile(uintptr(fd), F.ToString("net-udp-dial-", rAddr))
 	defer fdFile.Close()
 
 	c, err := net.FileConn(fdFile)
diff --git a/common/x/list/README.md b/common/x/list/README.md
new file mode 100644
index 0000000..0ac5af7
--- /dev/null
+++ b/common/x/list/README.md
@@ -0,0 +1,5 @@
+# x/list
+
+`list` with generic type
+
+upstream: go1.18
\ No newline at end of file
diff --git a/common/list/cond.go b/common/x/list/cond.go
similarity index 100%
rename from common/list/cond.go
rename to common/x/list/cond.go
diff --git a/common/list/list.go b/common/x/list/list.go
similarity index 100%
rename from common/list/list.go
rename to common/x/list/list.go
diff --git a/go.mod b/go.mod
index 5a21e74..fd587ee 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,4 @@ module github.com/sagernet/sing
 
 go 1.18
 
-require golang.org/x/sys v0.0.0-20220610221304-9f5ed59c137d
+require golang.org/x/sys v0.0.0-20220615213510-4f61da869c0c
diff --git a/go.sum b/go.sum
index 057668c..f140671 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,2 @@
-golang.org/x/sys v0.0.0-20220610221304-9f5ed59c137d h1:Zu/JngovGLVi6t2J3nmAf3AoTDwuzw85YZ3b9o4yU7s=
-golang.org/x/sys v0.0.0-20220610221304-9f5ed59c137d/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220615213510-4f61da869c0c h1:aFV+BgZ4svzjfabn8ERpuB4JI4N6/rdy1iusx77G3oU=
+golang.org/x/sys v0.0.0-20220615213510-4f61da869c0c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
diff --git a/protocol/http/listener.go b/protocol/http/listener.go
index 0cd0059..9a45fd6 100644
--- a/protocol/http/listener.go
+++ b/protocol/http/listener.go
@@ -4,7 +4,6 @@ import (
 	"bufio"
 	"context"
 	"encoding/base64"
-	"fmt"
 	"net"
 	"net/http"
 	"strings"
@@ -14,6 +13,7 @@ import (
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/auth"
 	E "github.com/sagernet/sing/common/exceptions"
+	F "github.com/sagernet/sing/common/format"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 )
@@ -49,7 +49,7 @@ func HandleRequest(ctx context.Context, request *http.Request, conn net.Conn, au
 				portStr = "80"
 			}
 			destination := M.ParseSocksaddrHostPortStr(request.URL.Hostname(), portStr)
-			_, err := fmt.Fprintf(conn, "HTTP/%d.%d %03d %s\r\n\r\n", request.ProtoMajor, request.ProtoMinor, http.StatusOK, "Connection established")
+			_, err := conn.Write([]byte(F.ToString("HTTP/", request.ProtoMajor, ".", request.ProtoMinor, " 200 Connection established\r\n\r\n")))
 			if err != nil {
 				return E.Cause(err, "write http response")
 			}
diff --git a/protocol/trojan/service.go b/protocol/trojan/service.go
index 72b3096..81b5c8d 100644
--- a/protocol/trojan/service.go
+++ b/protocol/trojan/service.go
@@ -2,13 +2,13 @@ package trojan
 
 import (
 	"context"
-	"fmt"
 	"io"
 	"net"
 
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/buf"
 	E "github.com/sagernet/sing/common/exceptions"
+	F "github.com/sagernet/sing/common/format"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 	"github.com/sagernet/sing/common/rw"
@@ -156,7 +156,7 @@ type Error struct {
 }
 
 func (e *Error) Error() string {
-	return fmt.Sprint("process connection from ", e.Metadata.Source, ": ", e.Inner.Error())
+	return F.ToString("process connection from ", e.Metadata.Source, ": ", e.Inner)
 }
 
 func (e *Error) Unwrap() error {