Remove varbin usages

adapter/experimental.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/binary"
+	"io"
 	"time"
 
 	"github.com/sagernet/sing/common/observable"
@@ -68,7 +69,11 @@ func (s *SavedBinary) MarshalBinary() ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	err = varbin.Write(&buffer, binary.BigEndian, s.Content)
+	_, err = varbin.WriteUvarint(&buffer, uint64(len(s.Content)))
+	if err != nil {
+		return nil, err
+	}
+	_, err = buffer.Write(s.Content)
 	if err != nil {
 		return nil, err
 	}
@@ -76,7 +81,11 @@ func (s *SavedBinary) MarshalBinary() ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	err = varbin.Write(&buffer, binary.BigEndian, s.LastEtag)
+	_, err = varbin.WriteUvarint(&buffer, uint64(len(s.LastEtag)))
+	if err != nil {
+		return nil, err
+	}
+	_, err = buffer.WriteString(s.LastEtag)
 	if err != nil {
 		return nil, err
 	}
@@ -90,7 +99,12 @@ func (s *SavedBinary) UnmarshalBinary(data []byte) error {
 	if err != nil {
 		return err
 	}
-	err = varbin.Read(reader, binary.BigEndian, &s.Content)
+	contentLength, err := binary.ReadUvarint(reader)
+	if err != nil {
+		return err
+	}
+	s.Content = make([]byte, contentLength)
+	_, err = io.ReadFull(reader, s.Content)
 	if err != nil {
 		return err
 	}
@@ -100,10 +114,16 @@ func (s *SavedBinary) UnmarshalBinary(data []byte) error {
 		return err
 	}
 	s.LastUpdated = time.Unix(lastUpdated, 0)
-	err = varbin.Read(reader, binary.BigEndian, &s.LastEtag)
+	etagLength, err := binary.ReadUvarint(reader)
 	if err != nil {
 		return err
 	}
+	etagBytes := make([]byte, etagLength)
+	_, err = io.ReadFull(reader, etagBytes)
+	if err != nil {
+		return err
+	}
+	s.LastEtag = string(etagBytes)
 	return nil
 }
 

common/geosite/compat_test.go

@@ -0,0 +1,234 @@
+package geosite
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/binary"
+	"strings"
+	"testing"
+
+	"github.com/sagernet/sing/common/varbin"
+
+	"github.com/stretchr/testify/require"
+)
+
+// Old implementation using varbin reflection-based serialization
+
+func oldWriteString(writer varbin.Writer, value string) error {
+	//nolint:staticcheck
+	return varbin.Write(writer, binary.BigEndian, value)
+}
+
+func oldWriteItem(writer varbin.Writer, item Item) error {
+	//nolint:staticcheck
+	return varbin.Write(writer, binary.BigEndian, item)
+}
+
+func oldReadString(reader varbin.Reader) (string, error) {
+	//nolint:staticcheck
+	return varbin.ReadValue[string](reader, binary.BigEndian)
+}
+
+func oldReadItem(reader varbin.Reader) (Item, error) {
+	//nolint:staticcheck
+	return varbin.ReadValue[Item](reader, binary.BigEndian)
+}
+
+func TestStringCompat(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name  string
+		input string
+	}{
+		{"empty", ""},
+		{"single_char", "a"},
+		{"ascii", "example.com"},
+		{"utf8", "测试域名.中国"},
+		{"special_chars", "\x00\xff\n\t"},
+		{"127_bytes", strings.Repeat("x", 127)},
+		{"128_bytes", strings.Repeat("x", 128)},
+		{"16383_bytes", strings.Repeat("x", 16383)},
+		{"16384_bytes", strings.Repeat("x", 16384)},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// Old write
+			var oldBuf bytes.Buffer
+			err := oldWriteString(&oldBuf, tc.input)
+			require.NoError(t, err)
+
+			// New write
+			var newBuf bytes.Buffer
+			err = writeString(&newBuf, tc.input)
+			require.NoError(t, err)
+
+			// Bytes must match
+			require.Equal(t, oldBuf.Bytes(), newBuf.Bytes(),
+				"mismatch for %q\nold: %x\nnew: %x", tc.name, oldBuf.Bytes(), newBuf.Bytes())
+
+			// New write -> old read
+			readBack, err := oldReadString(bufio.NewReader(bytes.NewReader(newBuf.Bytes())))
+			require.NoError(t, err)
+			require.Equal(t, tc.input, readBack)
+
+			// Old write -> new read
+			readBack2, err := readString(bufio.NewReader(bytes.NewReader(oldBuf.Bytes())))
+			require.NoError(t, err)
+			require.Equal(t, tc.input, readBack2)
+		})
+	}
+}
+
+func TestItemCompat(t *testing.T) {
+	t.Parallel()
+
+	// Note: varbin.Write has a bug where struct values (not pointers) don't write their fields
+	// because field.CanSet() returns false for non-addressable values.
+	// The old geosite code passed Item values to varbin.Write, which silently wrote nothing.
+	// The new code correctly writes Type + Value using manual serialization.
+	// This test verifies the new serialization format and round-trip correctness.
+
+	cases := []struct {
+		name  string
+		input Item
+	}{
+		{"domain_empty", Item{Type: RuleTypeDomain, Value: ""}},
+		{"domain_normal", Item{Type: RuleTypeDomain, Value: "example.com"}},
+		{"domain_suffix", Item{Type: RuleTypeDomainSuffix, Value: ".example.com"}},
+		{"domain_keyword", Item{Type: RuleTypeDomainKeyword, Value: "google"}},
+		{"domain_regex", Item{Type: RuleTypeDomainRegex, Value: `^.*\.example\.com$`}},
+		{"utf8_domain", Item{Type: RuleTypeDomain, Value: "测试.com"}},
+		{"long_domain", Item{Type: RuleTypeDomainSuffix, Value: strings.Repeat("a", 200) + ".com"}},
+		{"128_bytes_value", Item{Type: RuleTypeDomain, Value: strings.Repeat("x", 128)}},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// New write
+			var newBuf bytes.Buffer
+			err := newBuf.WriteByte(byte(tc.input.Type))
+			require.NoError(t, err)
+			err = writeString(&newBuf, tc.input.Value)
+			require.NoError(t, err)
+
+			// Verify format: Type (1 byte) + Value (uvarint len + bytes)
+			require.True(t, len(newBuf.Bytes()) >= 1, "output too short")
+			require.Equal(t, byte(tc.input.Type), newBuf.Bytes()[0], "type byte mismatch")
+
+			// New write -> old read (varbin can read correctly when given addressable target)
+			readBack, err := oldReadItem(bufio.NewReader(bytes.NewReader(newBuf.Bytes())))
+			require.NoError(t, err)
+			require.Equal(t, tc.input, readBack)
+
+			// New write -> new read
+			reader := bufio.NewReader(bytes.NewReader(newBuf.Bytes()))
+			typeByte, err := reader.ReadByte()
+			require.NoError(t, err)
+			value, err := readString(reader)
+			require.NoError(t, err)
+			require.Equal(t, tc.input, Item{Type: ItemType(typeByte), Value: value})
+		})
+	}
+}
+
+func TestGeositeWriteReadCompat(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name  string
+		input map[string][]Item
+	}{
+		{
+			"empty_map",
+			map[string][]Item{},
+		},
+		{
+			"single_code_empty_items",
+			map[string][]Item{"test": {}},
+		},
+		{
+			"single_code_single_item",
+			map[string][]Item{"test": {{Type: RuleTypeDomain, Value: "a.com"}}},
+		},
+		{
+			"single_code_multi_items",
+			map[string][]Item{
+				"test": {
+					{Type: RuleTypeDomain, Value: "a.com"},
+					{Type: RuleTypeDomainSuffix, Value: ".b.com"},
+					{Type: RuleTypeDomainKeyword, Value: "keyword"},
+					{Type: RuleTypeDomainRegex, Value: `^.*$`},
+				},
+			},
+		},
+		{
+			"multi_code",
+			map[string][]Item{
+				"cn": {{Type: RuleTypeDomain, Value: "baidu.com"}, {Type: RuleTypeDomainSuffix, Value: ".cn"}},
+				"us": {{Type: RuleTypeDomain, Value: "google.com"}},
+				"jp": {{Type: RuleTypeDomainSuffix, Value: ".jp"}},
+			},
+		},
+		{
+			"utf8_values",
+			map[string][]Item{
+				"test": {
+					{Type: RuleTypeDomain, Value: "测试.中国"},
+					{Type: RuleTypeDomainSuffix, Value: ".テスト"},
+				},
+			},
+		},
+		{
+			"large_items",
+			generateLargeItems(1000),
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// Write using new implementation
+			var buf bytes.Buffer
+			err := Write(&buf, tc.input)
+			require.NoError(t, err)
+
+			// Read back and verify
+			reader, codes, err := NewReader(bytes.NewReader(buf.Bytes()))
+			require.NoError(t, err)
+
+			// Verify all codes exist
+			codeSet := make(map[string]bool)
+			for _, code := range codes {
+				codeSet[code] = true
+			}
+			for code := range tc.input {
+				require.True(t, codeSet[code], "missing code: %s", code)
+			}
+
+			// Verify items match
+			for code, expectedItems := range tc.input {
+				items, err := reader.Read(code)
+				require.NoError(t, err)
+				require.Equal(t, expectedItems, items, "items mismatch for code: %s", code)
+			}
+		})
+	}
+}
+
+func generateLargeItems(count int) map[string][]Item {
+	items := make([]Item, count)
+	for i := 0; i < count; i++ {
+		items[i] = Item{
+			Type:  ItemType(i % 4),
+			Value: strings.Repeat("x", i%200) + ".com",
+		}
+	}
+	return map[string][]Item{"large": items}
+}

common/geosite/reader.go

@@ -9,7 +9,6 @@ import (
 	"sync/atomic"
 
 	E "github.com/sagernet/sing/common/exceptions"
-	"github.com/sagernet/sing/common/varbin"
 )
 
 type Reader struct {
@@ -78,7 +77,7 @@ func (r *Reader) readMetadata() error {
 			codeIndex  uint64
 			codeLength uint64
 		)
-		code, err = varbin.ReadValue[string](reader, binary.BigEndian)
+		code, err = readString(reader)
 		if err != nil {
 			return err
 		}
@@ -112,9 +111,16 @@ func (r *Reader) Read(code string) ([]Item, error) {
 	}
 	r.bufferedReader.Reset(r.reader)
 	itemList := make([]Item, r.domainLength[code])
-	err = varbin.Read(r.bufferedReader, binary.BigEndian, &itemList)
+	for i := range itemList {
-	if err != nil {
+		typeByte, err := r.bufferedReader.ReadByte()
-		return nil, err
+		if err != nil {
+			return nil, err
+		}
+		itemList[i].Type = ItemType(typeByte)
+		itemList[i].Value, err = readString(r.bufferedReader)
+		if err != nil {
+			return nil, err
+		}
 	}
 	return itemList, nil
 }
@@ -135,3 +141,18 @@ func (r *readCounter) Read(p []byte) (n int, err error) {
 	}
 	return
 }
+
+func readString(reader io.ByteReader) (string, error) {
+	length, err := binary.ReadUvarint(reader)
+	if err != nil {
+		return "", err
+	}
+	bytes := make([]byte, length)
+	for i := range bytes {
+		bytes[i], err = reader.ReadByte()
+		if err != nil {
+			return "", err
+		}
+	}
+	return string(bytes), nil
+}

common/geosite/writer.go

@@ -2,7 +2,6 @@ package geosite
 
 import (
 	"bytes"
-	"encoding/binary"
 	"sort"
 
 	"github.com/sagernet/sing/common/varbin"
@@ -20,7 +19,11 @@ func Write(writer varbin.Writer, domains map[string][]Item) error {
 	for _, code := range keys {
 		index[code] = content.Len()
 		for _, item := range domains[code] {
-			err := varbin.Write(content, binary.BigEndian, item)
+			err := content.WriteByte(byte(item.Type))
+			if err != nil {
+				return err
+			}
+			err = writeString(content, item.Value)
 			if err != nil {
 				return err
 			}
@@ -38,7 +41,7 @@ func Write(writer varbin.Writer, domains map[string][]Item) error {
 	}
 
 	for _, code := range keys {
-		err = varbin.Write(writer, binary.BigEndian, code)
+		err = writeString(writer, code)
 		if err != nil {
 			return err
 		}
@@ -59,3 +62,12 @@ func Write(writer varbin.Writer, domains map[string][]Item) error {
 
 	return nil
 }
+
+func writeString(writer varbin.Writer, value string) error {
+	_, err := varbin.WriteUvarint(writer, uint64(len(value)))
+	if err != nil {
+		return err
+	}
+	_, err = writer.Write([]byte(value))
+	return err
+}

common/srs/binary.go

@@ -6,6 +6,7 @@ import (
 	"encoding/binary"
 	"io"
 	"net/netip"
+	"unsafe"
 
 	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/option"
@@ -505,7 +506,24 @@ func writeDefaultRule(writer varbin.Writer, rule option.DefaultHeadlessRule, gen
 }
 
 func readRuleItemString(reader varbin.Reader) ([]string, error) {
-	return varbin.ReadValue[[]string](reader, binary.BigEndian)
+	length, err := binary.ReadUvarint(reader)
+	if err != nil {
+		return nil, err
+	}
+	result := make([]string, length)
+	for i := range result {
+		strLen, err := binary.ReadUvarint(reader)
+		if err != nil {
+			return nil, err
+		}
+		buf := make([]byte, strLen)
+		_, err = io.ReadFull(reader, buf)
+		if err != nil {
+			return nil, err
+		}
+		result[i] = string(buf)
+	}
+	return result, nil
 }
 
 func writeRuleItemString(writer varbin.Writer, itemType uint8, value []string) error {
@@ -513,11 +531,34 @@ func writeRuleItemString(writer varbin.Writer, itemType uint8, value []string) e
 	if err != nil {
 		return err
 	}
-	return varbin.Write(writer, binary.BigEndian, value)
+	_, err = varbin.WriteUvarint(writer, uint64(len(value)))
+	if err != nil {
+		return err
+	}
+	for _, s := range value {
+		_, err = varbin.WriteUvarint(writer, uint64(len(s)))
+		if err != nil {
+			return err
+		}
+		_, err = writer.Write([]byte(s))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
 }
 
 func readRuleItemUint8[E ~uint8](reader varbin.Reader) ([]E, error) {
-	return varbin.ReadValue[[]E](reader, binary.BigEndian)
+	length, err := binary.ReadUvarint(reader)
+	if err != nil {
+		return nil, err
+	}
+	result := make([]E, length)
+	_, err = io.ReadFull(reader, *(*[]byte)(unsafe.Pointer(&result)))
+	if err != nil {
+		return nil, err
+	}
+	return result, nil
 }
 
 func writeRuleItemUint8[E ~uint8](writer varbin.Writer, itemType uint8, value []E) error {
@@ -525,11 +566,25 @@ func writeRuleItemUint8[E ~uint8](writer varbin.Writer, itemType uint8, value []
 	if err != nil {
 		return err
 	}
-	return varbin.Write(writer, binary.BigEndian, value)
+	_, err = varbin.WriteUvarint(writer, uint64(len(value)))
+	if err != nil {
+		return err
+	}
+	_, err = writer.Write(*(*[]byte)(unsafe.Pointer(&value)))
+	return err
 }
 
 func readRuleItemUint16(reader varbin.Reader) ([]uint16, error) {
-	return varbin.ReadValue[[]uint16](reader, binary.BigEndian)
+	length, err := binary.ReadUvarint(reader)
+	if err != nil {
+		return nil, err
+	}
+	result := make([]uint16, length)
+	err = binary.Read(reader, binary.BigEndian, result)
+	if err != nil {
+		return nil, err
+	}
+	return result, nil
 }
 
 func writeRuleItemUint16(writer varbin.Writer, itemType uint8, value []uint16) error {
@@ -537,7 +592,11 @@ func writeRuleItemUint16(writer varbin.Writer, itemType uint8, value []uint16) e
 	if err != nil {
 		return err
 	}
-	return varbin.Write(writer, binary.BigEndian, value)
+	_, err = varbin.WriteUvarint(writer, uint64(len(value)))
+	if err != nil {
+		return err
+	}
+	return binary.Write(writer, binary.BigEndian, value)
 }
 
 func writeRuleItemCIDR(writer varbin.Writer, itemType uint8, value []string) error {

common/srs/compat_test.go

@@ -0,0 +1,494 @@
+package srs
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/binary"
+	"net/netip"
+	"strings"
+	"testing"
+	"unsafe"
+
+	M "github.com/sagernet/sing/common/metadata"
+	"github.com/sagernet/sing/common/varbin"
+
+	"github.com/stretchr/testify/require"
+	"go4.org/netipx"
+)
+
+// Old implementations using varbin reflection-based serialization
+
+func oldWriteStringSlice(writer varbin.Writer, value []string) error {
+	//nolint:staticcheck
+	return varbin.Write(writer, binary.BigEndian, value)
+}
+
+func oldReadStringSlice(reader varbin.Reader) ([]string, error) {
+	//nolint:staticcheck
+	return varbin.ReadValue[[]string](reader, binary.BigEndian)
+}
+
+func oldWriteUint8Slice[E ~uint8](writer varbin.Writer, value []E) error {
+	//nolint:staticcheck
+	return varbin.Write(writer, binary.BigEndian, value)
+}
+
+func oldReadUint8Slice[E ~uint8](reader varbin.Reader) ([]E, error) {
+	//nolint:staticcheck
+	return varbin.ReadValue[[]E](reader, binary.BigEndian)
+}
+
+func oldWriteUint16Slice(writer varbin.Writer, value []uint16) error {
+	//nolint:staticcheck
+	return varbin.Write(writer, binary.BigEndian, value)
+}
+
+func oldReadUint16Slice(reader varbin.Reader) ([]uint16, error) {
+	//nolint:staticcheck
+	return varbin.ReadValue[[]uint16](reader, binary.BigEndian)
+}
+
+func oldWritePrefix(writer varbin.Writer, prefix netip.Prefix) error {
+	//nolint:staticcheck
+	err := varbin.Write(writer, binary.BigEndian, prefix.Addr().AsSlice())
+	if err != nil {
+		return err
+	}
+	return binary.Write(writer, binary.BigEndian, uint8(prefix.Bits()))
+}
+
+type oldIPRangeData struct {
+	From []byte
+	To   []byte
+}
+
+// Note: The old writeIPSet had a bug where varbin.Write(writer, binary.BigEndian, data)
+// with a struct VALUE (not pointer) silently wrote nothing because field.CanSet() returned false.
+// This caused IP range data to be missing from the output.
+// The new implementation correctly writes all range data.
+//
+// The old readIPSet used varbin.Read with a pre-allocated slice, which worked because
+// slice elements are addressable and CanSet() returns true for them.
+//
+// For compatibility testing, we verify:
+// 1. New write produces correct output with range data
+// 2. New read can parse the new format correctly
+// 3. Round-trip works correctly
+
+func oldReadIPSet(reader varbin.Reader) (*netipx.IPSet, error) {
+	version, err := reader.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+	if version != 1 {
+		return nil, err
+	}
+	var length uint64
+	err = binary.Read(reader, binary.BigEndian, &length)
+	if err != nil {
+		return nil, err
+	}
+	ranges := make([]oldIPRangeData, length)
+	//nolint:staticcheck
+	err = varbin.Read(reader, binary.BigEndian, &ranges)
+	if err != nil {
+		return nil, err
+	}
+	mySet := &myIPSet{
+		rr: make([]myIPRange, len(ranges)),
+	}
+	for i, rangeData := range ranges {
+		mySet.rr[i].from = M.AddrFromIP(rangeData.From)
+		mySet.rr[i].to = M.AddrFromIP(rangeData.To)
+	}
+	return (*netipx.IPSet)(unsafe.Pointer(mySet)), nil
+}
+
+// New write functions (without itemType prefix for testing)
+
+func newWriteStringSlice(writer varbin.Writer, value []string) error {
+	_, err := varbin.WriteUvarint(writer, uint64(len(value)))
+	if err != nil {
+		return err
+	}
+	for _, s := range value {
+		_, err = varbin.WriteUvarint(writer, uint64(len(s)))
+		if err != nil {
+			return err
+		}
+		_, err = writer.Write([]byte(s))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func newWriteUint8Slice[E ~uint8](writer varbin.Writer, value []E) error {
+	_, err := varbin.WriteUvarint(writer, uint64(len(value)))
+	if err != nil {
+		return err
+	}
+	_, err = writer.Write(*(*[]byte)(unsafe.Pointer(&value)))
+	return err
+}
+
+func newWriteUint16Slice(writer varbin.Writer, value []uint16) error {
+	_, err := varbin.WriteUvarint(writer, uint64(len(value)))
+	if err != nil {
+		return err
+	}
+	return binary.Write(writer, binary.BigEndian, value)
+}
+
+func newWritePrefix(writer varbin.Writer, prefix netip.Prefix) error {
+	addrSlice := prefix.Addr().AsSlice()
+	_, err := varbin.WriteUvarint(writer, uint64(len(addrSlice)))
+	if err != nil {
+		return err
+	}
+	_, err = writer.Write(addrSlice)
+	if err != nil {
+		return err
+	}
+	return writer.WriteByte(uint8(prefix.Bits()))
+}
+
+// Tests
+
+func TestStringSliceCompat(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name  string
+		input []string
+	}{
+		{"nil", nil},
+		{"empty", []string{}},
+		{"single_empty", []string{""}},
+		{"single", []string{"test"}},
+		{"multi", []string{"a", "b", "c"}},
+		{"with_empty", []string{"a", "", "c"}},
+		{"utf8", []string{"测试", "テスト", "тест"}},
+		{"long_string", []string{strings.Repeat("x", 128)}},
+		{"many_elements", generateStrings(128)},
+		{"many_elements_256", generateStrings(256)},
+		{"127_byte_string", []string{strings.Repeat("x", 127)}},
+		{"128_byte_string", []string{strings.Repeat("x", 128)}},
+		{"mixed_lengths", []string{"a", strings.Repeat("b", 100), "", strings.Repeat("c", 200)}},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// Old write
+			var oldBuf bytes.Buffer
+			err := oldWriteStringSlice(&oldBuf, tc.input)
+			require.NoError(t, err)
+
+			// New write
+			var newBuf bytes.Buffer
+			err = newWriteStringSlice(&newBuf, tc.input)
+			require.NoError(t, err)
+
+			// Bytes must match
+			require.Equal(t, oldBuf.Bytes(), newBuf.Bytes(),
+				"mismatch for %q\nold: %x\nnew: %x", tc.name, oldBuf.Bytes(), newBuf.Bytes())
+
+			// New write -> old read
+			readBack, err := oldReadStringSlice(bufio.NewReader(bytes.NewReader(newBuf.Bytes())))
+			require.NoError(t, err)
+			requireStringSliceEqual(t, tc.input, readBack)
+
+			// Old write -> new read
+			readBack2, err := readRuleItemString(bufio.NewReader(bytes.NewReader(oldBuf.Bytes())))
+			require.NoError(t, err)
+			requireStringSliceEqual(t, tc.input, readBack2)
+		})
+	}
+}
+
+func TestUint8SliceCompat(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name  string
+		input []uint8
+	}{
+		{"nil", nil},
+		{"empty", []uint8{}},
+		{"single_zero", []uint8{0}},
+		{"single_max", []uint8{255}},
+		{"multi", []uint8{0, 1, 127, 128, 255}},
+		{"boundary", []uint8{0x00, 0x7f, 0x80, 0xff}},
+		{"sequential", generateUint8Slice(256)},
+		{"127_elements", generateUint8Slice(127)},
+		{"128_elements", generateUint8Slice(128)},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// Old write
+			var oldBuf bytes.Buffer
+			err := oldWriteUint8Slice(&oldBuf, tc.input)
+			require.NoError(t, err)
+
+			// New write
+			var newBuf bytes.Buffer
+			err = newWriteUint8Slice(&newBuf, tc.input)
+			require.NoError(t, err)
+
+			// Bytes must match
+			require.Equal(t, oldBuf.Bytes(), newBuf.Bytes(),
+				"mismatch for %q\nold: %x\nnew: %x", tc.name, oldBuf.Bytes(), newBuf.Bytes())
+
+			// New write -> old read
+			readBack, err := oldReadUint8Slice[uint8](bufio.NewReader(bytes.NewReader(newBuf.Bytes())))
+			require.NoError(t, err)
+			requireUint8SliceEqual(t, tc.input, readBack)
+
+			// Old write -> new read
+			readBack2, err := readRuleItemUint8[uint8](bufio.NewReader(bytes.NewReader(oldBuf.Bytes())))
+			require.NoError(t, err)
+			requireUint8SliceEqual(t, tc.input, readBack2)
+		})
+	}
+}
+
+func TestUint16SliceCompat(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name  string
+		input []uint16
+	}{
+		{"nil", nil},
+		{"empty", []uint16{}},
+		{"single_zero", []uint16{0}},
+		{"single_max", []uint16{65535}},
+		{"multi", []uint16{0, 255, 256, 32767, 32768, 65535}},
+		{"ports", []uint16{80, 443, 8080, 8443}},
+		{"127_elements", generateUint16Slice(127)},
+		{"128_elements", generateUint16Slice(128)},
+		{"256_elements", generateUint16Slice(256)},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// Old write
+			var oldBuf bytes.Buffer
+			err := oldWriteUint16Slice(&oldBuf, tc.input)
+			require.NoError(t, err)
+
+			// New write
+			var newBuf bytes.Buffer
+			err = newWriteUint16Slice(&newBuf, tc.input)
+			require.NoError(t, err)
+
+			// Bytes must match
+			require.Equal(t, oldBuf.Bytes(), newBuf.Bytes(),
+				"mismatch for %q\nold: %x\nnew: %x", tc.name, oldBuf.Bytes(), newBuf.Bytes())
+
+			// New write -> old read
+			readBack, err := oldReadUint16Slice(bufio.NewReader(bytes.NewReader(newBuf.Bytes())))
+			require.NoError(t, err)
+			requireUint16SliceEqual(t, tc.input, readBack)
+
+			// Old write -> new read
+			readBack2, err := readRuleItemUint16(bufio.NewReader(bytes.NewReader(oldBuf.Bytes())))
+			require.NoError(t, err)
+			requireUint16SliceEqual(t, tc.input, readBack2)
+		})
+	}
+}
+
+func TestPrefixCompat(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name  string
+		input netip.Prefix
+	}{
+		{"ipv4_0", netip.MustParsePrefix("0.0.0.0/0")},
+		{"ipv4_8", netip.MustParsePrefix("10.0.0.0/8")},
+		{"ipv4_16", netip.MustParsePrefix("192.168.0.0/16")},
+		{"ipv4_24", netip.MustParsePrefix("192.168.1.0/24")},
+		{"ipv4_32", netip.MustParsePrefix("1.2.3.4/32")},
+		{"ipv6_0", netip.MustParsePrefix("::/0")},
+		{"ipv6_64", netip.MustParsePrefix("2001:db8::/64")},
+		{"ipv6_128", netip.MustParsePrefix("::1/128")},
+		{"ipv6_full", netip.MustParsePrefix("2001:0db8:85a3:0000:0000:8a2e:0370:7334/128")},
+		{"ipv4_private", netip.MustParsePrefix("172.16.0.0/12")},
+		{"ipv6_link_local", netip.MustParsePrefix("fe80::/10")},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// Old write
+			var oldBuf bytes.Buffer
+			err := oldWritePrefix(&oldBuf, tc.input)
+			require.NoError(t, err)
+
+			// New write
+			var newBuf bytes.Buffer
+			err = newWritePrefix(&newBuf, tc.input)
+			require.NoError(t, err)
+
+			// Bytes must match
+			require.Equal(t, oldBuf.Bytes(), newBuf.Bytes(),
+				"mismatch for %q\nold: %x\nnew: %x", tc.name, oldBuf.Bytes(), newBuf.Bytes())
+
+			// New write -> new read (no old read for prefix)
+			readBack, err := readPrefix(bufio.NewReader(bytes.NewReader(newBuf.Bytes())))
+			require.NoError(t, err)
+			require.Equal(t, tc.input, readBack)
+
+			// Old write -> new read
+			readBack2, err := readPrefix(bufio.NewReader(bytes.NewReader(oldBuf.Bytes())))
+			require.NoError(t, err)
+			require.Equal(t, tc.input, readBack2)
+		})
+	}
+}
+
+func TestIPSetCompat(t *testing.T) {
+	t.Parallel()
+
+	// Note: The old writeIPSet was buggy (varbin.Write with struct values wrote nothing).
+	// This test verifies the new implementation writes correct data and round-trips correctly.
+
+	cases := []struct {
+		name  string
+		input *netipx.IPSet
+	}{
+		{"single_ipv4", buildIPSet("1.2.3.4")},
+		{"ipv4_range", buildIPSet("192.168.0.0/16")},
+		{"multi_ipv4", buildIPSet("10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16")},
+		{"single_ipv6", buildIPSet("::1")},
+		{"ipv6_range", buildIPSet("2001:db8::/32")},
+		{"mixed", buildIPSet("10.0.0.0/8", "::1", "2001:db8::/32")},
+		{"large", buildLargeIPSet(100)},
+		{"adjacent_ranges", buildIPSet("192.168.0.0/24", "192.168.1.0/24", "192.168.2.0/24")},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// New write
+			var newBuf bytes.Buffer
+			err := writeIPSet(&newBuf, tc.input)
+			require.NoError(t, err)
+
+			// Verify format starts with version byte (1) + uint64 count
+			require.True(t, len(newBuf.Bytes()) >= 9, "output too short")
+			require.Equal(t, byte(1), newBuf.Bytes()[0], "version byte mismatch")
+
+			// New write -> old read (varbin.Read with pre-allocated slice works correctly)
+			readBack, err := oldReadIPSet(bufio.NewReader(bytes.NewReader(newBuf.Bytes())))
+			require.NoError(t, err)
+			requireIPSetEqual(t, tc.input, readBack)
+
+			// New write -> new read
+			readBack2, err := readIPSet(bufio.NewReader(bytes.NewReader(newBuf.Bytes())))
+			require.NoError(t, err)
+			requireIPSetEqual(t, tc.input, readBack2)
+		})
+	}
+}
+
+// Helper functions
+
+func generateStrings(count int) []string {
+	result := make([]string, count)
+	for i := range result {
+		result[i] = strings.Repeat("x", i%50)
+	}
+	return result
+}
+
+func generateUint8Slice(count int) []uint8 {
+	result := make([]uint8, count)
+	for i := range result {
+		result[i] = uint8(i % 256)
+	}
+	return result
+}
+
+func generateUint16Slice(count int) []uint16 {
+	result := make([]uint16, count)
+	for i := range result {
+		result[i] = uint16(i * 257)
+	}
+	return result
+}
+
+func buildIPSet(cidrs ...string) *netipx.IPSet {
+	var builder netipx.IPSetBuilder
+	for _, cidr := range cidrs {
+		prefix, err := netip.ParsePrefix(cidr)
+		if err != nil {
+			addr, err := netip.ParseAddr(cidr)
+			if err != nil {
+				panic(err)
+			}
+			builder.Add(addr)
+		} else {
+			builder.AddPrefix(prefix)
+		}
+	}
+	set, _ := builder.IPSet()
+	return set
+}
+
+func buildLargeIPSet(count int) *netipx.IPSet {
+	var builder netipx.IPSetBuilder
+	for i := 0; i < count; i++ {
+		prefix := netip.PrefixFrom(netip.AddrFrom4([4]byte{10, byte(i / 256), byte(i % 256), 0}), 24)
+		builder.AddPrefix(prefix)
+	}
+	set, _ := builder.IPSet()
+	return set
+}
+
+func requireStringSliceEqual(t *testing.T, expected, actual []string) {
+	t.Helper()
+	if len(expected) == 0 && len(actual) == 0 {
+		return
+	}
+	require.Equal(t, expected, actual)
+}
+
+func requireUint8SliceEqual(t *testing.T, expected, actual []uint8) {
+	t.Helper()
+	if len(expected) == 0 && len(actual) == 0 {
+		return
+	}
+	require.Equal(t, expected, actual)
+}
+
+func requireUint16SliceEqual(t *testing.T, expected, actual []uint16) {
+	t.Helper()
+	if len(expected) == 0 && len(actual) == 0 {
+		return
+	}
+	require.Equal(t, expected, actual)
+}
+
+func requireIPSetEqual(t *testing.T, expected, actual *netipx.IPSet) {
+	t.Helper()
+	expectedRanges := expected.Ranges()
+	actualRanges := actual.Ranges()
+	require.Equal(t, len(expectedRanges), len(actualRanges), "range count mismatch")
+	for i := range expectedRanges {
+		require.Equal(t, expectedRanges[i].From(), actualRanges[i].From(), "range[%d].from mismatch", i)
+		require.Equal(t, expectedRanges[i].To(), actualRanges[i].To(), "range[%d].to mismatch", i)
+	}
+}

common/srs/ip_cidr.go

@@ -2,6 +2,7 @@ package srs
 
 import (
 	"encoding/binary"
+	"io"
 	"net/netip"
 
 	M "github.com/sagernet/sing/common/metadata"
@@ -9,11 +10,16 @@ import (
 )
 
 func readPrefix(reader varbin.Reader) (netip.Prefix, error) {
-	addrSlice, err := varbin.ReadValue[[]byte](reader, binary.BigEndian)
+	addrLen, err := binary.ReadUvarint(reader)
 	if err != nil {
 		return netip.Prefix{}, err
 	}
-	prefixBits, err := varbin.ReadValue[uint8](reader, binary.BigEndian)
+	addrSlice := make([]byte, addrLen)
+	_, err = io.ReadFull(reader, addrSlice)
+	if err != nil {
+		return netip.Prefix{}, err
+	}
+	prefixBits, err := reader.ReadByte()
 	if err != nil {
 		return netip.Prefix{}, err
 	}
@@ -21,11 +27,16 @@ func readPrefix(reader varbin.Reader) (netip.Prefix, error) {
 }
 
 func writePrefix(writer varbin.Writer, prefix netip.Prefix) error {
-	err := varbin.Write(writer, binary.BigEndian, prefix.Addr().AsSlice())
+	addrSlice := prefix.Addr().AsSlice()
+	_, err := varbin.WriteUvarint(writer, uint64(len(addrSlice)))
 	if err != nil {
 		return err
 	}
-	err = binary.Write(writer, binary.BigEndian, uint8(prefix.Bits()))
+	_, err = writer.Write(addrSlice)
+	if err != nil {
+		return err
+	}
+	err = writer.WriteByte(uint8(prefix.Bits()))
 	if err != nil {
 		return err
 	}

common/srs/ip_set.go

@@ -2,11 +2,11 @@ package srs
 
 import (
 	"encoding/binary"
+	"io"
 	"net/netip"
 	"os"
 	"unsafe"
 
-	"github.com/sagernet/sing/common"
 	M "github.com/sagernet/sing/common/metadata"
 	"github.com/sagernet/sing/common/varbin"
 
@@ -22,11 +22,6 @@ type myIPRange struct {
 	to   netip.Addr
 }
 
-type myIPRangeData struct {
-	From []byte
-	To   []byte
-}
-
 func readIPSet(reader varbin.Reader) (*netipx.IPSet, error) {
 	version, err := reader.ReadByte()
 	if err != nil {
@@ -41,17 +36,30 @@ func readIPSet(reader varbin.Reader) (*netipx.IPSet, error) {
 	if err != nil {
 		return nil, err
 	}
-	ranges := make([]myIPRangeData, length)
-	err = varbin.Read(reader, binary.BigEndian, &ranges)
-	if err != nil {
-		return nil, err
-	}
 	mySet := &myIPSet{
-		rr: make([]myIPRange, len(ranges)),
+		rr: make([]myIPRange, length),
 	}
-	for i, rangeData := range ranges {
+	for i := range mySet.rr {
-		mySet.rr[i].from = M.AddrFromIP(rangeData.From)
+		fromLen, err := binary.ReadUvarint(reader)
-		mySet.rr[i].to = M.AddrFromIP(rangeData.To)
+		if err != nil {
+			return nil, err
+		}
+		fromBytes := make([]byte, fromLen)
+		_, err = io.ReadFull(reader, fromBytes)
+		if err != nil {
+			return nil, err
+		}
+		toLen, err := binary.ReadUvarint(reader)
+		if err != nil {
+			return nil, err
+		}
+		toBytes := make([]byte, toLen)
+		_, err = io.ReadFull(reader, toBytes)
+		if err != nil {
+			return nil, err
+		}
+		mySet.rr[i].from = M.AddrFromIP(fromBytes)
+		mySet.rr[i].to = M.AddrFromIP(toBytes)
 	}
 	return (*netipx.IPSet)(unsafe.Pointer(mySet)), nil
 }
@@ -61,18 +69,27 @@ func writeIPSet(writer varbin.Writer, set *netipx.IPSet) error {
 	if err != nil {
 		return err
 	}
-	dataList := common.Map((*myIPSet)(unsafe.Pointer(set)).rr, func(rr myIPRange) myIPRangeData {
+	mySet := (*myIPSet)(unsafe.Pointer(set))
-		return myIPRangeData{
+	err = binary.Write(writer, binary.BigEndian, uint64(len(mySet.rr)))
-			From: rr.from.AsSlice(),
-			To:   rr.to.AsSlice(),
-		}
-	})
-	err = binary.Write(writer, binary.BigEndian, uint64(len(dataList)))
 	if err != nil {
 		return err
 	}
-	for _, data := range dataList {
+	for _, rr := range mySet.rr {
-		err = varbin.Write(writer, binary.BigEndian, data)
+		fromBytes := rr.from.AsSlice()
+		_, err = varbin.WriteUvarint(writer, uint64(len(fromBytes)))
+		if err != nil {
+			return err
+		}
+		_, err = writer.Write(fromBytes)
+		if err != nil {
+			return err
+		}
+		toBytes := rr.to.AsSlice()
+		_, err = varbin.WriteUvarint(writer, uint64(len(toBytes)))
+		if err != nil {
+			return err
+		}
+		_, err = writer.Write(toBytes)
 		if err != nil {
 			return err
 		}

experimental/libbox/profile_import.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"compress/gzip"
 	"encoding/binary"
+	"io"
 
 	E "github.com/sagernet/sing/common/exceptions"
 	"github.com/sagernet/sing/common/varbin"
@@ -35,7 +36,7 @@ type ErrorMessage struct {
 func (e *ErrorMessage) Encode() []byte {
 	var buffer bytes.Buffer
 	buffer.WriteByte(MessageTypeError)
-	varbin.Write(&buffer, binary.BigEndian, e.Message)
+	writeString(&buffer, e.Message)
 	return buffer.Bytes()
 }
 
@@ -49,7 +50,7 @@ func DecodeErrorMessage(data []byte) (*ErrorMessage, error) {
 		return nil, E.New("invalid message")
 	}
 	var message ErrorMessage
-	message.Message, err = varbin.ReadValue[string](reader, binary.BigEndian)
+	message.Message, err = readString(reader)
 	if err != nil {
 		return nil, err
 	}
@@ -87,7 +88,7 @@ func (e *ProfileEncoder) Encode() []byte {
 	binary.Write(&buffer, binary.BigEndian, uint16(len(e.profiles)))
 	for _, preview := range e.profiles {
 		binary.Write(&buffer, binary.BigEndian, preview.ProfileID)
-		varbin.Write(&buffer, binary.BigEndian, preview.Name)
+		writeString(&buffer, preview.Name)
 		binary.Write(&buffer, binary.BigEndian, preview.Type)
 	}
 	return buffer.Bytes()
@@ -117,7 +118,7 @@ func (d *ProfileDecoder) Decode(data []byte) error {
 		if err != nil {
 			return err
 		}
-		profile.Name, err = varbin.ReadValue[string](reader, binary.BigEndian)
+		profile.Name, err = readString(reader)
 		if err != nil {
 			return err
 		}
@@ -178,11 +179,11 @@ func (c *ProfileContent) Encode() []byte {
 	buffer.WriteByte(1)
 	gWriter := gzip.NewWriter(buffer)
 	writer := bufio.NewWriter(gWriter)
-	varbin.Write(writer, binary.BigEndian, c.Name)
+	writeStringBuffered(writer, c.Name)
 	binary.Write(writer, binary.BigEndian, c.Type)
-	varbin.Write(writer, binary.BigEndian, c.Config)
+	writeStringBuffered(writer, c.Config)
 	if c.Type != ProfileTypeLocal {
-		varbin.Write(writer, binary.BigEndian, c.RemotePath)
+		writeStringBuffered(writer, c.RemotePath)
 	}
 	if c.Type == ProfileTypeRemote {
 		binary.Write(writer, binary.BigEndian, c.AutoUpdate)
@@ -214,7 +215,7 @@ func DecodeProfileContent(data []byte) (*ProfileContent, error) {
 	}
 	bReader := varbin.StubReader(gReader)
 	var content ProfileContent
-	content.Name, err = varbin.ReadValue[string](bReader, binary.BigEndian)
+	content.Name, err = readString(bReader)
 	if err != nil {
 		return nil, err
 	}
@@ -222,12 +223,12 @@ func DecodeProfileContent(data []byte) (*ProfileContent, error) {
 	if err != nil {
 		return nil, err
 	}
-	content.Config, err = varbin.ReadValue[string](bReader, binary.BigEndian)
+	content.Config, err = readString(bReader)
 	if err != nil {
 		return nil, err
 	}
 	if content.Type != ProfileTypeLocal {
-		content.RemotePath, err = varbin.ReadValue[string](bReader, binary.BigEndian)
+		content.RemotePath, err = readString(bReader)
 		if err != nil {
 			return nil, err
 		}
@@ -250,3 +251,28 @@ func DecodeProfileContent(data []byte) (*ProfileContent, error) {
 	}
 	return &content, nil
 }
+
+func readString(reader io.ByteReader) (string, error) {
+	length, err := binary.ReadUvarint(reader)
+	if err != nil {
+		return "", err
+	}
+	buf := make([]byte, length)
+	for i := range buf {
+		buf[i], err = reader.ReadByte()
+		if err != nil {
+			return "", err
+		}
+	}
+	return string(buf), nil
+}
+
+func writeString(buffer *bytes.Buffer, value string) {
+	varbin.WriteUvarint(buffer, uint64(len(value)))
+	buffer.WriteString(value)
+}
+
+func writeStringBuffered(writer *bufio.Writer, value string) {
+	varbin.WriteUvarint(writer, uint64(len(value)))
+	writer.WriteString(value)
+}

go.mod

@@ -33,7 +33,7 @@ require (
 	github.com/sagernet/gomobile v0.1.11
 	github.com/sagernet/gvisor v0.0.0-20250811.0-sing-box-mod.1
 	github.com/sagernet/quic-go v0.59.0-sing-box-mod.2
-	github.com/sagernet/sing v0.8.0-beta.11
+	github.com/sagernet/sing v0.8.0-beta.12
 	github.com/sagernet/sing-mux v0.3.4
 	github.com/sagernet/sing-quic v0.6.0-beta.11
 	github.com/sagernet/sing-shadowsocks v0.2.8

go.sum

@@ -210,8 +210,8 @@ github.com/sagernet/nftables v0.3.0-beta.4 h1:kbULlAwAC3jvdGAC1P5Fa3GSxVwQJibNen
 github.com/sagernet/nftables v0.3.0-beta.4/go.mod h1:OQXAjvjNGGFxaTgVCSTRIhYB5/llyVDeapVoENYBDS8=
 github.com/sagernet/quic-go v0.59.0-sing-box-mod.2 h1:hJUL+HtxEOjxsa0CsucbBVqI/AMS4k52NwNU637zmdw=
 github.com/sagernet/quic-go v0.59.0-sing-box-mod.2/go.mod h1:OqILvS182CyOol5zNNo6bguvOGgXzV459+chpRaUC+4=
-github.com/sagernet/sing v0.8.0-beta.11 h1:nn/2Uod61b5rLHnXCuaFcbDxI1oRCodaxjzjt7Mobe4=
+github.com/sagernet/sing v0.8.0-beta.12 h1:Xt0MNk6i6vI9f2vV6QkwhgiLB0g53fZSVsCCBEtQ8qQ=
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