diff --git a/.github/workflows/debug.yml b/.github/workflows/debug.yml
index c5378d2..f023f61 100644
--- a/.github/workflows/debug.yml
+++ b/.github/workflows/debug.yml
@@ -30,7 +30,7 @@ jobs:
         uses: actions/setup-go@v2
         with:
           go-version: ${{ steps.version.outputs.go_version }}
-      - name: Build
+      - name: Add cache to Go proxy
         run: |
           version=`git rev-parse HEAD`
           mkdir build
@@ -38,4 +38,9 @@ jobs:
           go mod init build
           go get -v github.com/sagernet/sing@$version
           popd
-          go build -v ./...
\ No newline at end of file
+        continue-on-error: true
+      - name: Build
+        run: |
+          make test
+          make lint_install
+          make lint
\ No newline at end of file
diff --git a/.golangci.yml b/.golangci.yml
index b81d894..5c439f7 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -3,14 +3,14 @@ linters:
   enable:
     - gofumpt
     - govet
-    - gci
+#    - gci
     - staticcheck
 
 linters-settings:
-  gci:
-    sections:
-      - standard
-      - prefix(github.com/sagernet/)
-      - default
+#  gci:
+#    sections:
+#      - standard
+#      - prefix(github.com/sagernet/)
+#      - default
   staticcheck:
-    go: '1.18'
+    go: '1.19'
diff --git a/Makefile b/Makefile
index a2950e2..6f7c6f1 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,11 @@
 fmt:
-	gofumpt -l -w .
-	gofmt -s -w .
-	gci write -s "standard,prefix(github.com/sagernet/),default" .
+	@gofumpt -l -w .
+	@gofmt -s -w .
+	@gci write -s "standard,prefix(github.com/sagernet/),default" .
 
-lint_install:
-	go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
+fmt_install:
+	go install -v mvdan.cc/gofumpt@latest
+	go install -v github.com/daixiang0/gci@v0.4.0
 
 lint:
 	GOOS=linux golangci-lint run ./...
@@ -12,10 +13,8 @@ lint:
 	GOOS=darwin golangci-lint run ./...
 	GOOS=freebsd golangci-lint run ./...
 
-test:
-	go test -v .
+lint_install:
+	go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
 
-update:
-	git fetch
-	git reset FETCH_HEAD --hard
-	git clean -fdx
\ No newline at end of file
+test:
+	go test -v ./...
\ No newline at end of file
diff --git a/common/ranges/range.go b/common/ranges/range.go
new file mode 100644
index 0000000..28fdf24
--- /dev/null
+++ b/common/ranges/range.go
@@ -0,0 +1,112 @@
+package ranges
+
+import (
+	"sort"
+
+	"github.com/sagernet/sing/common/x/constraints"
+)
+
+type Range[N comparable] struct {
+	Start N
+	End   N
+}
+
+func New[N constraints.Integer](start N, end N) Range[N] {
+	return Range[N]{start, end}
+}
+
+func NewSingle[N constraints.Integer](index N) Range[N] {
+	return Range[N]{index, index}
+}
+
+func Merge[N constraints.Integer](ranges []Range[N]) (mergedRanges []Range[N]) {
+	if len(ranges) == 0 {
+		return
+	}
+	sort.Slice(ranges, func(i, j int) bool {
+		return ranges[i].Start < ranges[j].Start
+	})
+	mergedRanges = ranges[:1]
+	var rangeIndex N
+	for _, r := range ranges[1:] {
+		if r.Start > mergedRanges[rangeIndex].End+1 {
+			mergedRanges = append(mergedRanges, r)
+			rangeIndex++
+		} else if r.End > mergedRanges[rangeIndex].End {
+			mergedRanges[rangeIndex].End = r.End
+		}
+	}
+	return
+}
+
+func Revert[N constraints.Integer](start, end N, ranges []Range[N]) (revertedRanges []Range[N]) {
+	if len(ranges) == 0 {
+		return
+	}
+	ranges = Merge(ranges)
+	if ranges[0].Start > start {
+		revertedRanges = append(revertedRanges, Range[N]{start, ranges[0].Start - 1})
+	}
+	rangeEnd := ranges[0].End
+	for _, r := range ranges[1:] {
+		if r.Start > rangeEnd+1 {
+			revertedRanges = append(revertedRanges, Range[N]{rangeEnd + 1, r.Start - 1})
+		}
+		rangeEnd = r.End
+	}
+	if end > rangeEnd {
+		revertedRanges = append(revertedRanges, Range[N]{rangeEnd + 1, end})
+	}
+	return
+}
+
+func Exclude[N constraints.Integer](ranges []Range[N], targetRanges []Range[N]) []Range[N] {
+	ranges = Merge(ranges)
+	if len(ranges) == 0 {
+		return nil
+	}
+	targetRanges = Merge(targetRanges)
+	if len(targetRanges) == 0 {
+		return ranges
+	}
+	var mergedRanges []Range[N]
+	rangeStart := ranges[0].Start
+	rangeEnd := ranges[0].End
+	rangeIndex := rangeStart
+	ranges = ranges[1:]
+	targetStart := targetRanges[0].Start
+	targetEnd := targetRanges[0].End
+	targetRanges = targetRanges[1:]
+	for {
+		if targetStart > rangeEnd {
+			if rangeIndex <= rangeEnd {
+				mergedRanges = append(mergedRanges, Range[N]{rangeIndex, rangeEnd})
+			}
+			if len(ranges) == 0 {
+				break
+			}
+			rangeStart = ranges[0].Start
+			rangeEnd = ranges[0].End
+			rangeIndex = rangeStart
+			ranges = ranges[1:]
+			continue
+		}
+		if targetStart > rangeIndex {
+			mergedRanges = append(mergedRanges, Range[N]{rangeIndex, targetStart - 1})
+			rangeIndex = targetStart + 1
+		}
+		if targetEnd <= rangeEnd {
+			rangeIndex = targetEnd + 1
+			if len(targetRanges) == 0 {
+				break
+			}
+			targetStart = targetRanges[0].Start
+			targetEnd = targetRanges[0].End
+			targetRanges = targetRanges[1:]
+		}
+	}
+	if rangeIndex <= rangeEnd {
+		mergedRanges = append(mergedRanges, Range[N]{rangeIndex, rangeEnd})
+	}
+	return Merge(append(mergedRanges, ranges...))
+}
diff --git a/common/ranges/range_test.go b/common/ranges/range_test.go
new file mode 100644
index 0000000..d4dad35
--- /dev/null
+++ b/common/ranges/range_test.go
@@ -0,0 +1,194 @@
+package ranges
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestRevertRanges(t *testing.T) {
+	for _, testRange := range []struct {
+		start, end int
+		ranges     []Range[int]
+		expected   []Range[int]
+	}{
+		{
+			start: 0,
+			end:   10,
+			ranges: []Range[int]{
+				{0, 1},
+			},
+			expected: []Range[int]{
+				{2, 10},
+			},
+		},
+		{
+			start: 0,
+			end:   10,
+			ranges: []Range[int]{
+				{9, 10},
+			},
+			expected: []Range[int]{
+				{0, 8},
+			},
+		},
+		{
+			start: 0,
+			end:   10,
+			ranges: []Range[int]{
+				{0, 1},
+				{9, 10},
+			},
+			expected: []Range[int]{
+				{2, 8},
+			},
+		},
+		{
+			start: 0,
+			end:   10,
+			ranges: []Range[int]{
+				{2, 4},
+				{6, 8},
+			},
+			expected: []Range[int]{
+				{0, 1},
+				{5, 5},
+				{9, 10},
+			},
+		},
+		{
+			start: 0,
+			end:   10,
+			ranges: []Range[int]{
+				{2, 4},
+				{8, 9},
+			},
+			expected: []Range[int]{
+				{0, 1},
+				{5, 7},
+				{10, 10},
+			},
+		},
+	} {
+		result := Revert(testRange.start, testRange.end, testRange.ranges)
+		if !reflect.DeepEqual(result, testRange.expected) {
+			t.Fatal("expected", testRange.expected, "\ngot", result)
+		}
+	}
+}
+
+func TestMergeRanges(t *testing.T) {
+	for _, testRange := range []struct {
+		ranges   []Range[int]
+		expected []Range[int]
+	}{
+		{
+			ranges: []Range[int]{
+				{0, 1},
+				{1, 2},
+			},
+			expected: []Range[int]{
+				{0, 2},
+			},
+		},
+		{
+			ranges: []Range[int]{
+				{0, 3},
+				{5, 7},
+				{8, 9},
+				{10, 10},
+			},
+			expected: []Range[int]{
+				{0, 3},
+				{5, 10},
+			},
+		},
+		{
+			ranges: []Range[int]{
+				{1, 3},
+				{2, 6},
+				{8, 10},
+				{15, 18},
+			},
+			expected: []Range[int]{
+				{1, 6},
+				{8, 10},
+				{15, 18},
+			},
+		},
+		{
+			ranges: []Range[int]{
+				{1, 3},
+				{2, 7},
+				{2, 6},
+			},
+			expected: []Range[int]{
+				{1, 7},
+			},
+		},
+		{
+			ranges: []Range[int]{
+				{1, 3},
+				{2, 6},
+				{2, 7},
+			},
+			expected: []Range[int]{
+				{1, 7},
+			},
+		},
+	} {
+		result := Merge(testRange.ranges)
+		if !reflect.DeepEqual(result, testRange.expected) {
+			t.Fatal("input", testRange.ranges, "\nexpected", testRange.expected, "\ngot", result)
+		}
+	}
+}
+
+func TestExcludeRanges(t *testing.T) {
+	for _, testRange := range []struct {
+		ranges   []Range[int]
+		exclude  []Range[int]
+		expected []Range[int]
+	}{
+		{
+			ranges: []Range[int]{
+				{0, 100},
+			},
+			exclude: []Range[int]{
+				{0, 10},
+				{20, 30},
+				{55, 55},
+			},
+			expected: []Range[int]{
+				{11, 19},
+				{31, 54},
+				{56, 100},
+			},
+		},
+		{
+			ranges: []Range[int]{
+				{0, 100},
+				{200, 300},
+			},
+			exclude: []Range[int]{
+				{0, 10},
+				{20, 30},
+				{55, 55},
+				{250, 250},
+				{299, 299},
+			},
+			expected: []Range[int]{
+				{11, 19},
+				{31, 54},
+				{56, 100},
+				{200, 249},
+				{251, 298},
+				{300, 300},
+			},
+		},
+	} {
+		result := Exclude(testRange.ranges, testRange.exclude)
+		if !reflect.DeepEqual(result, testRange.expected) {
+			t.Fatal("input", testRange.ranges, testRange.exclude, "\nexpected", testRange.expected, "\ngot", result)
+		}
+	}
+}