113 lines
4.2 KiB
Go
113 lines
4.2 KiB
Go
package tun
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"math/bits"
|
|
)
|
|
|
|
// TODO: Explore SIMD and/or other assembly optimizations.
|
|
func checksumNoFold(b []byte, initial uint64) uint64 {
|
|
tmp := make([]byte, 8)
|
|
binary.NativeEndian.PutUint64(tmp, initial)
|
|
ac := binary.BigEndian.Uint64(tmp)
|
|
var carry uint64
|
|
|
|
for len(b) >= 128 {
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[:8]), 0)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[8:16]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[16:24]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[24:32]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[32:40]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[40:48]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[48:56]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[56:64]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[64:72]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[72:80]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[80:88]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[88:96]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[96:104]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[104:112]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[112:120]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[120:128]), carry)
|
|
ac += carry
|
|
b = b[128:]
|
|
}
|
|
if len(b) >= 64 {
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[:8]), 0)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[8:16]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[16:24]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[24:32]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[32:40]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[40:48]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[48:56]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[56:64]), carry)
|
|
ac += carry
|
|
b = b[64:]
|
|
}
|
|
if len(b) >= 32 {
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[:8]), 0)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[8:16]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[16:24]), carry)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[24:32]), carry)
|
|
ac += carry
|
|
b = b[32:]
|
|
}
|
|
if len(b) >= 16 {
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[:8]), 0)
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[8:16]), carry)
|
|
ac += carry
|
|
b = b[16:]
|
|
}
|
|
if len(b) >= 8 {
|
|
ac, carry = bits.Add64(ac, binary.NativeEndian.Uint64(b[:8]), 0)
|
|
ac += carry
|
|
b = b[8:]
|
|
}
|
|
if len(b) >= 4 {
|
|
ac, carry = bits.Add64(ac, uint64(binary.NativeEndian.Uint32(b[:4])), 0)
|
|
ac += carry
|
|
b = b[4:]
|
|
}
|
|
if len(b) >= 2 {
|
|
ac, carry = bits.Add64(ac, uint64(binary.NativeEndian.Uint16(b[:2])), 0)
|
|
ac += carry
|
|
b = b[2:]
|
|
}
|
|
if len(b) == 1 {
|
|
tmp := binary.NativeEndian.Uint16([]byte{b[0], 0})
|
|
ac, carry = bits.Add64(ac, uint64(tmp), 0)
|
|
ac += carry
|
|
}
|
|
|
|
binary.NativeEndian.PutUint64(tmp, ac)
|
|
return binary.BigEndian.Uint64(tmp)
|
|
}
|
|
|
|
func checksum(b []byte, initial uint64) uint16 {
|
|
ac := checksumNoFold(b, initial)
|
|
ac = (ac >> 16) + (ac & 0xffff)
|
|
ac = (ac >> 16) + (ac & 0xffff)
|
|
ac = (ac >> 16) + (ac & 0xffff)
|
|
ac = (ac >> 16) + (ac & 0xffff)
|
|
return uint16(ac)
|
|
}
|
|
|
|
// Checksum computes an IP checksum starting with the provided initial value.
|
|
func Checksum(data []byte, initial uint16) uint16 {
|
|
return checksum(data, uint64(initial))
|
|
}
|
|
|
|
func pseudoHeaderChecksumNoFold(protocol uint8, srcAddr, dstAddr []byte, totalLen uint16) uint64 {
|
|
sum := checksumNoFold(srcAddr, 0)
|
|
sum = checksumNoFold(dstAddr, sum)
|
|
sum = checksumNoFold([]byte{0, protocol}, sum)
|
|
tmp := make([]byte, 2)
|
|
binary.BigEndian.PutUint16(tmp, totalLen)
|
|
return checksumNoFold(tmp, sum)
|
|
}
|
|
|
|
// PseudoHeaderChecksum computes an IP pseudo-header checksum. srcAddr and
|
|
// dstAddr must be 4 or 16 bytes in length.
|
|
func PseudoHeaderChecksum(protocol uint8, srcAddr, dstAddr []byte, totalLen uint16) uint16 {
|
|
return checksum([]byte{}, pseudoHeaderChecksumNoFold(protocol, srcAddr, dstAddr, totalLen))
|
|
}
|