chore: reduce data copying in quic sniffer and better handle data fragmentation and overlap

common/utils/ranges.go

@@ -3,6 +3,7 @@ package utils
 import (
 	"errors"
 	"fmt"
+	"sort"
 	"strconv"
 	"strings"
 
@@ -149,3 +150,24 @@ func (ranges IntRanges[T]) Range(f func(t T) bool) {
 		}
 	}
 }
+
+func (ranges IntRanges[T]) Merge() (mergedRanges IntRanges[T]) {
+	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 int
+	for _, r := range ranges[1:] {
+		if mergedRanges[rangeIndex].End()+1 > mergedRanges[rangeIndex].End() && // integer overflow
+			r.Start() > mergedRanges[rangeIndex].End()+1 {
+			mergedRanges = append(mergedRanges, r)
+			rangeIndex++
+		} else if r.End() > mergedRanges[rangeIndex].End() {
+			mergedRanges[rangeIndex].end = r.End()
+		}
+	}
+	return
+}

common/utils/ranges_test.go

@@ -0,0 +1,82 @@
+package utils
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestMergeRanges(t *testing.T) {
+	t.Parallel()
+	for _, testRange := range []struct {
+		ranges   IntRanges[uint16]
+		expected IntRanges[uint16]
+	}{
+		{
+			ranges: IntRanges[uint16]{
+				NewRange[uint16](0, 1),
+				NewRange[uint16](1, 2),
+			},
+			expected: IntRanges[uint16]{
+				NewRange[uint16](0, 2),
+			},
+		},
+		{
+			ranges: IntRanges[uint16]{
+				NewRange[uint16](0, 3),
+				NewRange[uint16](5, 7),
+				NewRange[uint16](8, 9),
+				NewRange[uint16](10, 10),
+			},
+			expected: IntRanges[uint16]{
+				NewRange[uint16](0, 3),
+				NewRange[uint16](5, 10),
+			},
+		},
+		{
+			ranges: IntRanges[uint16]{
+				NewRange[uint16](1, 3),
+				NewRange[uint16](2, 6),
+				NewRange[uint16](8, 10),
+				NewRange[uint16](15, 18),
+			},
+			expected: IntRanges[uint16]{
+				NewRange[uint16](1, 6),
+				NewRange[uint16](8, 10),
+				NewRange[uint16](15, 18),
+			},
+		},
+		{
+			ranges: IntRanges[uint16]{
+				NewRange[uint16](1, 3),
+				NewRange[uint16](2, 7),
+				NewRange[uint16](2, 6),
+			},
+			expected: IntRanges[uint16]{
+				NewRange[uint16](1, 7),
+			},
+		},
+		{
+			ranges: IntRanges[uint16]{
+				NewRange[uint16](1, 3),
+				NewRange[uint16](2, 6),
+				NewRange[uint16](2, 7),
+			},
+			expected: IntRanges[uint16]{
+				NewRange[uint16](1, 7),
+			},
+		},
+		{
+			ranges: IntRanges[uint16]{
+				NewRange[uint16](1, 3),
+				NewRange[uint16](2, 65535),
+				NewRange[uint16](2, 7),
+				NewRange[uint16](3, 16),
+			},
+			expected: IntRanges[uint16]{
+				NewRange[uint16](1, 65535),
+			},
+		},
+	} {
+		assert.Equal(t, testRange.expected, testRange.ranges.Merge())
+	}
+}