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checksum.go
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//go:build linux
package tunnel
import "encoding/binary"
func checksumNoFold(b []byte, initial uint64) uint64 {
ac := initial
for len(b) >= 128 {
ac += uint64(binary.BigEndian.Uint32(b[:4]))
ac += uint64(binary.BigEndian.Uint32(b[4:8]))
ac += uint64(binary.BigEndian.Uint32(b[8:12]))
ac += uint64(binary.BigEndian.Uint32(b[12:16]))
ac += uint64(binary.BigEndian.Uint32(b[16:20]))
ac += uint64(binary.BigEndian.Uint32(b[20:24]))
ac += uint64(binary.BigEndian.Uint32(b[24:28]))
ac += uint64(binary.BigEndian.Uint32(b[28:32]))
ac += uint64(binary.BigEndian.Uint32(b[32:36]))
ac += uint64(binary.BigEndian.Uint32(b[36:40]))
ac += uint64(binary.BigEndian.Uint32(b[40:44]))
ac += uint64(binary.BigEndian.Uint32(b[44:48]))
ac += uint64(binary.BigEndian.Uint32(b[48:52]))
ac += uint64(binary.BigEndian.Uint32(b[52:56]))
ac += uint64(binary.BigEndian.Uint32(b[56:60]))
ac += uint64(binary.BigEndian.Uint32(b[60:64]))
ac += uint64(binary.BigEndian.Uint32(b[64:68]))
ac += uint64(binary.BigEndian.Uint32(b[68:72]))
ac += uint64(binary.BigEndian.Uint32(b[72:76]))
ac += uint64(binary.BigEndian.Uint32(b[76:80]))
ac += uint64(binary.BigEndian.Uint32(b[80:84]))
ac += uint64(binary.BigEndian.Uint32(b[84:88]))
ac += uint64(binary.BigEndian.Uint32(b[88:92]))
ac += uint64(binary.BigEndian.Uint32(b[92:96]))
ac += uint64(binary.BigEndian.Uint32(b[96:100]))
ac += uint64(binary.BigEndian.Uint32(b[100:104]))
ac += uint64(binary.BigEndian.Uint32(b[104:108]))
ac += uint64(binary.BigEndian.Uint32(b[108:112]))
ac += uint64(binary.BigEndian.Uint32(b[112:116]))
ac += uint64(binary.BigEndian.Uint32(b[116:120]))
ac += uint64(binary.BigEndian.Uint32(b[120:124]))
ac += uint64(binary.BigEndian.Uint32(b[124:128]))
b = b[128:]
}
if len(b) >= 64 {
ac += uint64(binary.BigEndian.Uint32(b[:4]))
ac += uint64(binary.BigEndian.Uint32(b[4:8]))
ac += uint64(binary.BigEndian.Uint32(b[8:12]))
ac += uint64(binary.BigEndian.Uint32(b[12:16]))
ac += uint64(binary.BigEndian.Uint32(b[16:20]))
ac += uint64(binary.BigEndian.Uint32(b[20:24]))
ac += uint64(binary.BigEndian.Uint32(b[24:28]))
ac += uint64(binary.BigEndian.Uint32(b[28:32]))
ac += uint64(binary.BigEndian.Uint32(b[32:36]))
ac += uint64(binary.BigEndian.Uint32(b[36:40]))
ac += uint64(binary.BigEndian.Uint32(b[40:44]))
ac += uint64(binary.BigEndian.Uint32(b[44:48]))
ac += uint64(binary.BigEndian.Uint32(b[48:52]))
ac += uint64(binary.BigEndian.Uint32(b[52:56]))
ac += uint64(binary.BigEndian.Uint32(b[56:60]))
ac += uint64(binary.BigEndian.Uint32(b[60:64]))
b = b[64:]
}
if len(b) >= 32 {
ac += uint64(binary.BigEndian.Uint32(b[:4]))
ac += uint64(binary.BigEndian.Uint32(b[4:8]))
ac += uint64(binary.BigEndian.Uint32(b[8:12]))
ac += uint64(binary.BigEndian.Uint32(b[12:16]))
ac += uint64(binary.BigEndian.Uint32(b[16:20]))
ac += uint64(binary.BigEndian.Uint32(b[20:24]))
ac += uint64(binary.BigEndian.Uint32(b[24:28]))
ac += uint64(binary.BigEndian.Uint32(b[28:32]))
b = b[32:]
}
if len(b) >= 16 {
ac += uint64(binary.BigEndian.Uint32(b[:4]))
ac += uint64(binary.BigEndian.Uint32(b[4:8]))
ac += uint64(binary.BigEndian.Uint32(b[8:12]))
ac += uint64(binary.BigEndian.Uint32(b[12:16]))
b = b[16:]
}
if len(b) >= 8 {
ac += uint64(binary.BigEndian.Uint32(b[:4]))
ac += uint64(binary.BigEndian.Uint32(b[4:8]))
b = b[8:]
}
if len(b) >= 4 {
ac += uint64(binary.BigEndian.Uint32(b))
b = b[4:]
}
if len(b) >= 2 {
ac += uint64(binary.BigEndian.Uint16(b))
b = b[2:]
}
if len(b) == 1 {
ac += uint64(b[0]) << 8
}
return ac
}
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)
}
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)
}
func gsoNoneChecksum(buff []byte, start, off uint16) {
csum := start + off
initial := binary.BigEndian.Uint16(buff[csum:])
buff[csum], buff[csum+1] = 0, 0
binary.BigEndian.PutUint16(buff[csum:], ^checksum(buff[start:], uint64(initial)))
}
func checksumValid(pkt []byte, iphLen, proto uint8, isV6 bool) bool {
srcAddrAt := ipv4SrcAddrOffset
addrSize := 4
if isV6 {
srcAddrAt = ipv6SrcAddrOffset
addrSize = 16
}
lenForPseudo := uint16(len(pkt) - int(iphLen))
cSum := pseudoHeaderChecksumNoFold(proto,
pkt[srcAddrAt:srcAddrAt+addrSize],
pkt[srcAddrAt+addrSize:srcAddrAt+addrSize*2], lenForPseudo)
return ^checksum(pkt[iphLen:], cSum) == 0
}