Make gtcpip public for external use

internal/gtcpip/checksum/checksum.go

@@ -1,45 +0,0 @@
-// Copyright 2018 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 checksum provides the implementation of the encoding and decoding of
-// network protocol headers.
-package checksum
-
-import (
-	"encoding/binary"
-)
-
-// Size is the size of a checksum.
-//
-// The checksum is held in a uint16 which is 2 bytes.
-const Size = 2
-
-// Put puts the checksum in the provided byte slice.
-func Put(b []byte, xsum uint16) {
-	binary.BigEndian.PutUint16(b, xsum)
-}
-
-// Combine combines the two uint16 to form their checksum. This is done
-// by adding them and the carry.
-//
-// Note that checksum a must have been computed on an even number of bytes.
-func Combine(a, b uint16) uint16 {
-	v := uint32(a) + uint32(b)
-	return uint16(v + v>>16)
-}
-
-func ChecksumDefault(buf []byte, initial uint16) uint16 {
-	s, _ := calculateChecksum(buf, false, initial)
-	return s
-}