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-rw-r--r--pkg/tcpip/header/checksum.go124
-rw-r--r--pkg/tcpip/header/checksum_test.go62
2 files changed, 186 insertions, 0 deletions
diff --git a/pkg/tcpip/header/checksum.go b/pkg/tcpip/header/checksum.go
index 9749c7f4d..ce57b581a 100644
--- a/pkg/tcpip/header/checksum.go
+++ b/pkg/tcpip/header/checksum.go
@@ -45,6 +45,121 @@ func calculateChecksum(buf []byte, odd bool, initial uint32) (uint16, bool) {
return ChecksumCombine(uint16(v), uint16(v>>16)), odd
}
+func unrolledCalculateChecksum(buf []byte, odd bool, initial uint32) (uint16, bool) {
+ v := initial
+
+ if odd {
+ v += uint32(buf[0])
+ buf = buf[1:]
+ }
+
+ l := len(buf)
+ odd = l&1 != 0
+ if odd {
+ l--
+ v += uint32(buf[l]) << 8
+ }
+ for (l - 64) >= 0 {
+ i := 0
+ v += (uint32(buf[i]) << 8) + uint32(buf[i+1])
+ v += (uint32(buf[i+2]) << 8) + uint32(buf[i+3])
+ v += (uint32(buf[i+4]) << 8) + uint32(buf[i+5])
+ v += (uint32(buf[i+6]) << 8) + uint32(buf[i+7])
+ v += (uint32(buf[i+8]) << 8) + uint32(buf[i+9])
+ v += (uint32(buf[i+10]) << 8) + uint32(buf[i+11])
+ v += (uint32(buf[i+12]) << 8) + uint32(buf[i+13])
+ v += (uint32(buf[i+14]) << 8) + uint32(buf[i+15])
+ i += 16
+ v += (uint32(buf[i]) << 8) + uint32(buf[i+1])
+ v += (uint32(buf[i+2]) << 8) + uint32(buf[i+3])
+ v += (uint32(buf[i+4]) << 8) + uint32(buf[i+5])
+ v += (uint32(buf[i+6]) << 8) + uint32(buf[i+7])
+ v += (uint32(buf[i+8]) << 8) + uint32(buf[i+9])
+ v += (uint32(buf[i+10]) << 8) + uint32(buf[i+11])
+ v += (uint32(buf[i+12]) << 8) + uint32(buf[i+13])
+ v += (uint32(buf[i+14]) << 8) + uint32(buf[i+15])
+ i += 16
+ v += (uint32(buf[i]) << 8) + uint32(buf[i+1])
+ v += (uint32(buf[i+2]) << 8) + uint32(buf[i+3])
+ v += (uint32(buf[i+4]) << 8) + uint32(buf[i+5])
+ v += (uint32(buf[i+6]) << 8) + uint32(buf[i+7])
+ v += (uint32(buf[i+8]) << 8) + uint32(buf[i+9])
+ v += (uint32(buf[i+10]) << 8) + uint32(buf[i+11])
+ v += (uint32(buf[i+12]) << 8) + uint32(buf[i+13])
+ v += (uint32(buf[i+14]) << 8) + uint32(buf[i+15])
+ i += 16
+ v += (uint32(buf[i]) << 8) + uint32(buf[i+1])
+ v += (uint32(buf[i+2]) << 8) + uint32(buf[i+3])
+ v += (uint32(buf[i+4]) << 8) + uint32(buf[i+5])
+ v += (uint32(buf[i+6]) << 8) + uint32(buf[i+7])
+ v += (uint32(buf[i+8]) << 8) + uint32(buf[i+9])
+ v += (uint32(buf[i+10]) << 8) + uint32(buf[i+11])
+ v += (uint32(buf[i+12]) << 8) + uint32(buf[i+13])
+ v += (uint32(buf[i+14]) << 8) + uint32(buf[i+15])
+ buf = buf[64:]
+ l = l - 64
+ }
+ if (l - 32) >= 0 {
+ i := 0
+ v += (uint32(buf[i]) << 8) + uint32(buf[i+1])
+ v += (uint32(buf[i+2]) << 8) + uint32(buf[i+3])
+ v += (uint32(buf[i+4]) << 8) + uint32(buf[i+5])
+ v += (uint32(buf[i+6]) << 8) + uint32(buf[i+7])
+ v += (uint32(buf[i+8]) << 8) + uint32(buf[i+9])
+ v += (uint32(buf[i+10]) << 8) + uint32(buf[i+11])
+ v += (uint32(buf[i+12]) << 8) + uint32(buf[i+13])
+ v += (uint32(buf[i+14]) << 8) + uint32(buf[i+15])
+ i += 16
+ v += (uint32(buf[i]) << 8) + uint32(buf[i+1])
+ v += (uint32(buf[i+2]) << 8) + uint32(buf[i+3])
+ v += (uint32(buf[i+4]) << 8) + uint32(buf[i+5])
+ v += (uint32(buf[i+6]) << 8) + uint32(buf[i+7])
+ v += (uint32(buf[i+8]) << 8) + uint32(buf[i+9])
+ v += (uint32(buf[i+10]) << 8) + uint32(buf[i+11])
+ v += (uint32(buf[i+12]) << 8) + uint32(buf[i+13])
+ v += (uint32(buf[i+14]) << 8) + uint32(buf[i+15])
+ buf = buf[32:]
+ l = l - 32
+ }
+ if (l - 16) >= 0 {
+ i := 0
+ v += (uint32(buf[i]) << 8) + uint32(buf[i+1])
+ v += (uint32(buf[i+2]) << 8) + uint32(buf[i+3])
+ v += (uint32(buf[i+4]) << 8) + uint32(buf[i+5])
+ v += (uint32(buf[i+6]) << 8) + uint32(buf[i+7])
+ v += (uint32(buf[i+8]) << 8) + uint32(buf[i+9])
+ v += (uint32(buf[i+10]) << 8) + uint32(buf[i+11])
+ v += (uint32(buf[i+12]) << 8) + uint32(buf[i+13])
+ v += (uint32(buf[i+14]) << 8) + uint32(buf[i+15])
+ buf = buf[16:]
+ l = l - 16
+ }
+ if (l - 8) >= 0 {
+ i := 0
+ v += (uint32(buf[i]) << 8) + uint32(buf[i+1])
+ v += (uint32(buf[i+2]) << 8) + uint32(buf[i+3])
+ v += (uint32(buf[i+4]) << 8) + uint32(buf[i+5])
+ v += (uint32(buf[i+6]) << 8) + uint32(buf[i+7])
+ buf = buf[8:]
+ l = l - 8
+ }
+ if (l - 4) >= 0 {
+ i := 0
+ v += (uint32(buf[i]) << 8) + uint32(buf[i+1])
+ v += (uint32(buf[i+2]) << 8) + uint32(buf[i+3])
+ buf = buf[4:]
+ l = l - 4
+ }
+
+ // At this point since l was even before we started unrolling
+ // there can be only two bytes left to add.
+ if l != 0 {
+ v += (uint32(buf[0]) << 8) + uint32(buf[1])
+ }
+
+ return ChecksumCombine(uint16(v), uint16(v>>16)), odd
+}
+
// Checksum calculates the checksum (as defined in RFC 1071) of the bytes in the
// given byte array.
//
@@ -54,6 +169,15 @@ func Checksum(buf []byte, initial uint16) uint16 {
return s
}
+// UnrolledChecksum calculates the checksum (as defined in RFC 1071) of the
+// bytes in the given byte array.
+//
+// The initial checksum must have been computed on an even number of bytes.
+func UnrolledChecksum(buf []byte, initial uint16) uint16 {
+ s, _ := unrolledCalculateChecksum(buf, false, uint32(initial))
+ return s
+}
+
// ChecksumVV calculates the checksum (as defined in RFC 1071) of the bytes in
// the given VectorizedView.
//
diff --git a/pkg/tcpip/header/checksum_test.go b/pkg/tcpip/header/checksum_test.go
index 86b466c1c..2fbd16a65 100644
--- a/pkg/tcpip/header/checksum_test.go
+++ b/pkg/tcpip/header/checksum_test.go
@@ -17,6 +17,8 @@
package header_test
import (
+ "fmt"
+ "math/rand"
"testing"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
@@ -107,3 +109,63 @@ func TestChecksumVVWithOffset(t *testing.T) {
})
}
}
+
+func TestChecksum(t *testing.T) {
+ var bufSizes = []int{0, 1, 2, 3, 4, 7, 8, 15, 16, 31, 32, 63, 64, 127, 128, 255, 256, 257, 1023, 1024}
+ type testCase struct {
+ buf []byte
+ initial uint16
+ csumOrig uint16
+ csumNew uint16
+ }
+ testCases := make([]testCase, 100000)
+ // Ensure same buffer generation for test consistency.
+ rnd := rand.New(rand.NewSource(42))
+ for i := range testCases {
+ testCases[i].buf = make([]byte, bufSizes[i%len(bufSizes)])
+ testCases[i].initial = uint16(rnd.Intn(65536))
+ rnd.Read(testCases[i].buf)
+ }
+
+ for i := range testCases {
+ testCases[i].csumOrig = header.Checksum(testCases[i].buf, testCases[i].initial)
+ testCases[i].csumNew = header.UnrolledChecksum(testCases[i].buf, testCases[i].initial)
+ if got, want := testCases[i].csumNew, testCases[i].csumOrig; got != want {
+ t.Fatalf("new checksum for (buf = %x, initial = %d) does not match old got: %d, want: %d", testCases[i].buf, testCases[i].initial, got, want)
+ }
+ }
+}
+
+func BenchmarkChecksum(b *testing.B) {
+ var bufSizes = []int{64, 128, 256, 512, 1024, 1500, 2048, 4096, 8192, 16384, 32767, 32768, 65535, 65536}
+
+ checkSumImpls := []struct {
+ fn func([]byte, uint16) uint16
+ name string
+ }{
+ {header.Checksum, fmt.Sprintf("checksum")},
+ {header.UnrolledChecksum, fmt.Sprintf("unrolled_checksum")},
+ }
+
+ for _, csumImpl := range checkSumImpls {
+ // Ensure same buffer generation for test consistency.
+ rnd := rand.New(rand.NewSource(42))
+ for _, bufSz := range bufSizes {
+ b.Run(fmt.Sprintf("%s_%d", csumImpl.name, bufSz), func(b *testing.B) {
+ tc := struct {
+ buf []byte
+ initial uint16
+ csum uint16
+ }{
+ buf: make([]byte, bufSz),
+ initial: uint16(rnd.Intn(65536)),
+ }
+ rnd.Read(tc.buf)
+ b.ResetTimer()
+ for i := 0; i < b.N; i++ {
+ tc.csum = csumImpl.fn(tc.buf, tc.initial)
+ }
+ })
+ }
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-06 03:31:46 +0000