119 lines
4.2 KiB
Go
119 lines
4.2 KiB
Go
package tun
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import "encoding/binary"
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// TODO: Explore SIMD and/or other assembly optimizations.
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// TODO: Test native endian loads. See RFC 1071 section 2 part B.
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func checksumNoFold(b []byte, initial uint64) uint64 {
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ac := initial
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for len(b) >= 128 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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ac += uint64(binary.BigEndian.Uint32(b[8:12]))
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ac += uint64(binary.BigEndian.Uint32(b[12:16]))
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ac += uint64(binary.BigEndian.Uint32(b[16:20]))
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ac += uint64(binary.BigEndian.Uint32(b[20:24]))
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ac += uint64(binary.BigEndian.Uint32(b[24:28]))
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ac += uint64(binary.BigEndian.Uint32(b[28:32]))
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ac += uint64(binary.BigEndian.Uint32(b[32:36]))
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ac += uint64(binary.BigEndian.Uint32(b[36:40]))
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ac += uint64(binary.BigEndian.Uint32(b[40:44]))
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ac += uint64(binary.BigEndian.Uint32(b[44:48]))
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ac += uint64(binary.BigEndian.Uint32(b[48:52]))
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ac += uint64(binary.BigEndian.Uint32(b[52:56]))
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ac += uint64(binary.BigEndian.Uint32(b[56:60]))
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ac += uint64(binary.BigEndian.Uint32(b[60:64]))
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ac += uint64(binary.BigEndian.Uint32(b[64:68]))
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ac += uint64(binary.BigEndian.Uint32(b[68:72]))
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ac += uint64(binary.BigEndian.Uint32(b[72:76]))
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ac += uint64(binary.BigEndian.Uint32(b[76:80]))
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ac += uint64(binary.BigEndian.Uint32(b[80:84]))
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ac += uint64(binary.BigEndian.Uint32(b[84:88]))
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ac += uint64(binary.BigEndian.Uint32(b[88:92]))
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ac += uint64(binary.BigEndian.Uint32(b[92:96]))
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ac += uint64(binary.BigEndian.Uint32(b[96:100]))
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ac += uint64(binary.BigEndian.Uint32(b[100:104]))
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ac += uint64(binary.BigEndian.Uint32(b[104:108]))
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ac += uint64(binary.BigEndian.Uint32(b[108:112]))
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ac += uint64(binary.BigEndian.Uint32(b[112:116]))
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ac += uint64(binary.BigEndian.Uint32(b[116:120]))
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ac += uint64(binary.BigEndian.Uint32(b[120:124]))
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ac += uint64(binary.BigEndian.Uint32(b[124:128]))
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b = b[128:]
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}
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if len(b) >= 64 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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ac += uint64(binary.BigEndian.Uint32(b[8:12]))
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ac += uint64(binary.BigEndian.Uint32(b[12:16]))
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ac += uint64(binary.BigEndian.Uint32(b[16:20]))
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ac += uint64(binary.BigEndian.Uint32(b[20:24]))
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ac += uint64(binary.BigEndian.Uint32(b[24:28]))
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ac += uint64(binary.BigEndian.Uint32(b[28:32]))
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ac += uint64(binary.BigEndian.Uint32(b[32:36]))
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ac += uint64(binary.BigEndian.Uint32(b[36:40]))
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ac += uint64(binary.BigEndian.Uint32(b[40:44]))
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ac += uint64(binary.BigEndian.Uint32(b[44:48]))
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ac += uint64(binary.BigEndian.Uint32(b[48:52]))
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ac += uint64(binary.BigEndian.Uint32(b[52:56]))
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ac += uint64(binary.BigEndian.Uint32(b[56:60]))
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ac += uint64(binary.BigEndian.Uint32(b[60:64]))
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b = b[64:]
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}
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if len(b) >= 32 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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ac += uint64(binary.BigEndian.Uint32(b[8:12]))
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ac += uint64(binary.BigEndian.Uint32(b[12:16]))
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ac += uint64(binary.BigEndian.Uint32(b[16:20]))
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ac += uint64(binary.BigEndian.Uint32(b[20:24]))
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ac += uint64(binary.BigEndian.Uint32(b[24:28]))
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ac += uint64(binary.BigEndian.Uint32(b[28:32]))
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b = b[32:]
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}
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if len(b) >= 16 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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ac += uint64(binary.BigEndian.Uint32(b[8:12]))
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ac += uint64(binary.BigEndian.Uint32(b[12:16]))
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b = b[16:]
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}
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if len(b) >= 8 {
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ac += uint64(binary.BigEndian.Uint32(b[:4]))
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ac += uint64(binary.BigEndian.Uint32(b[4:8]))
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b = b[8:]
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}
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if len(b) >= 4 {
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ac += uint64(binary.BigEndian.Uint32(b))
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b = b[4:]
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}
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if len(b) >= 2 {
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ac += uint64(binary.BigEndian.Uint16(b))
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b = b[2:]
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}
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if len(b) == 1 {
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ac += uint64(b[0]) << 8
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}
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return ac
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}
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func checksum(b []byte, initial uint64) uint16 {
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ac := checksumNoFold(b, initial)
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ac = (ac >> 16) + (ac & 0xffff)
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ac = (ac >> 16) + (ac & 0xffff)
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ac = (ac >> 16) + (ac & 0xffff)
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ac = (ac >> 16) + (ac & 0xffff)
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return uint16(ac)
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}
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func pseudoHeaderChecksumNoFold(protocol uint8, srcAddr, dstAddr []byte, totalLen uint16) uint64 {
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sum := checksumNoFold(srcAddr, 0)
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sum = checksumNoFold(dstAddr, sum)
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sum = checksumNoFold([]byte{0, protocol}, sum)
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tmp := make([]byte, 2)
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binary.BigEndian.PutUint16(tmp, totalLen)
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return checksumNoFold(tmp, sum)
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}
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