diff options
Diffstat (limited to 'pkg/tcpip/header')
| -rw-r--r-- | pkg/tcpip/header/BUILD | 6 | ||||
| -rw-r--r-- | pkg/tcpip/header/checksum.go | 50 | ||||
| -rw-r--r-- | pkg/tcpip/header/checksum_test.go | 109 |
3 files changed, 153 insertions, 12 deletions
diff --git a/pkg/tcpip/header/BUILD b/pkg/tcpip/header/BUILD index de3c7e2c3..7b3189303 100644 --- a/pkg/tcpip/header/BUILD +++ b/pkg/tcpip/header/BUILD @@ -36,10 +36,14 @@ go_test( name = "header_x_test", size = "small", srcs = [ + "checksum_test.go", "ipversion_test.go", "tcp_test.go", ], - deps = [":header"], + deps = [ + ":header", + "//pkg/tcpip/buffer", + ], ) go_test( diff --git a/pkg/tcpip/header/checksum.go b/pkg/tcpip/header/checksum.go index 39a4d69be..9749c7f4d 100644 --- a/pkg/tcpip/header/checksum.go +++ b/pkg/tcpip/header/checksum.go @@ -23,11 +23,17 @@ import ( "gvisor.dev/gvisor/pkg/tcpip/buffer" ) -func calculateChecksum(buf []byte, initial uint32) uint16 { +func calculateChecksum(buf []byte, odd bool, initial uint32) (uint16, bool) { v := initial + if odd { + v += uint32(buf[0]) + buf = buf[1:] + } + l := len(buf) - if l&1 != 0 { + odd = l&1 != 0 + if odd { l-- v += uint32(buf[l]) << 8 } @@ -36,7 +42,7 @@ func calculateChecksum(buf []byte, initial uint32) uint16 { v += (uint32(buf[i]) << 8) + uint32(buf[i+1]) } - return ChecksumCombine(uint16(v), uint16(v>>16)) + return ChecksumCombine(uint16(v), uint16(v>>16)), odd } // Checksum calculates the checksum (as defined in RFC 1071) of the bytes in the @@ -44,7 +50,8 @@ func calculateChecksum(buf []byte, initial uint32) uint16 { // // The initial checksum must have been computed on an even number of bytes. func Checksum(buf []byte, initial uint16) uint16 { - return calculateChecksum(buf, uint32(initial)) + s, _ := calculateChecksum(buf, false, uint32(initial)) + return s } // ChecksumVV calculates the checksum (as defined in RFC 1071) of the bytes in @@ -52,19 +59,40 @@ func Checksum(buf []byte, initial uint16) uint16 { // // The initial checksum must have been computed on an even number of bytes. func ChecksumVV(vv buffer.VectorisedView, initial uint16) uint16 { - var odd bool + return ChecksumVVWithOffset(vv, initial, 0, vv.Size()) +} + +// ChecksumVVWithOffset calculates the checksum (as defined in RFC 1071) of the +// bytes in the given VectorizedView. +// +// The initial checksum must have been computed on an even number of bytes. +func ChecksumVVWithOffset(vv buffer.VectorisedView, initial uint16, off int, size int) uint16 { + odd := false sum := initial for _, v := range vv.Views() { if len(v) == 0 { continue } - s := uint32(sum) - if odd { - s += uint32(v[0]) - v = v[1:] + + if off >= len(v) { + off -= len(v) + continue + } + v = v[off:] + + l := len(v) + if l > size { + l = size + } + v = v[:l] + + sum, odd = calculateChecksum(v, odd, uint32(sum)) + + size -= len(v) + if size == 0 { + break } - odd = len(v)&1 != 0 - sum = calculateChecksum(v, s) + off = 0 } return sum } diff --git a/pkg/tcpip/header/checksum_test.go b/pkg/tcpip/header/checksum_test.go new file mode 100644 index 000000000..86b466c1c --- /dev/null +++ b/pkg/tcpip/header/checksum_test.go @@ -0,0 +1,109 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +// Package header provides the implementation of the encoding and decoding of +// network protocol headers. +package header_test + +import ( + "testing" + + "gvisor.dev/gvisor/pkg/tcpip/buffer" + "gvisor.dev/gvisor/pkg/tcpip/header" +) + +func TestChecksumVVWithOffset(t *testing.T) { + testCases := []struct { + name string + vv buffer.VectorisedView + off, size int + initial uint16 + want uint16 + }{ + { + name: "empty", + vv: buffer.NewVectorisedView(0, []buffer.View{ + buffer.NewViewFromBytes([]byte{1, 9, 0, 5, 4}), + }), + off: 0, + size: 0, + want: 0, + }, + { + name: "OneView", + vv: buffer.NewVectorisedView(0, []buffer.View{ + buffer.NewViewFromBytes([]byte{1, 9, 0, 5, 4}), + }), + off: 0, + size: 5, + want: 1294, + }, + { + name: "TwoViews", + vv: buffer.NewVectorisedView(0, []buffer.View{ + buffer.NewViewFromBytes([]byte{1, 9, 0, 5, 4}), + buffer.NewViewFromBytes([]byte{4, 3, 7, 1, 2, 123}), + }), + off: 0, + size: 11, + want: 33819, + }, + { + name: "TwoViewsWithOffset", + vv: buffer.NewVectorisedView(0, []buffer.View{ + buffer.NewViewFromBytes([]byte{98, 1, 9, 0, 5, 4}), + buffer.NewViewFromBytes([]byte{4, 3, 7, 1, 2, 123}), + }), + off: 1, + size: 11, + want: 33819, + }, + { + name: "ThreeViewsWithOffset", + vv: buffer.NewVectorisedView(0, []buffer.View{ + buffer.NewViewFromBytes([]byte{98, 1, 9, 0, 5, 4}), + buffer.NewViewFromBytes([]byte{98, 1, 9, 0, 5, 4}), + buffer.NewViewFromBytes([]byte{4, 3, 7, 1, 2, 123}), + }), + off: 7, + size: 11, + want: 33819, + }, + { + name: "ThreeViewsWithInitial", + vv: buffer.NewVectorisedView(0, []buffer.View{ + buffer.NewViewFromBytes([]byte{77, 11, 33, 0, 55, 44}), + buffer.NewViewFromBytes([]byte{98, 1, 9, 0, 5, 4}), + buffer.NewViewFromBytes([]byte{4, 3, 7, 1, 2, 123, 99}), + }), + initial: 77, + off: 7, + size: 11, + want: 33896, + }, + } + for _, tc := range testCases { + t.Run(tc.name, func(t *testing.T) { + if got, want := header.ChecksumVVWithOffset(tc.vv, tc.initial, tc.off, tc.size), tc.want; got != want { + t.Errorf("header.ChecksumVVWithOffset(%v) = %v, want: %v", tc, got, tc.want) + } + v := tc.vv.ToView() + v.TrimFront(tc.off) + v.CapLength(tc.size) + if got, want := header.Checksum(v, tc.initial), tc.want; got != want { + t.Errorf("header.Checksum(%v) = %v, want: %v", tc, got, tc.want) + } + }) + } +} |