diff options
Diffstat (limited to 'tun/checksum.go')
| -rw-r--r-- | tun/checksum.go | 100 |
1 files changed, 88 insertions, 12 deletions
diff --git a/tun/checksum.go b/tun/checksum.go index f4f8471..29a8fc8 100644 --- a/tun/checksum.go +++ b/tun/checksum.go @@ -3,23 +3,99 @@ package tun import "encoding/binary" // TODO: Explore SIMD and/or other assembly optimizations. +// TODO: Test native endian loads. See RFC 1071 section 2 part B. func checksumNoFold(b []byte, initial uint64) uint64 { ac := initial - i := 0 - n := len(b) - for n >= 4 { - ac += uint64(binary.BigEndian.Uint32(b[i : i+4])) - n -= 4 - i += 4 + + 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:] } - for n >= 2 { - ac += uint64(binary.BigEndian.Uint16(b[i : i+2])) - n -= 2 - i += 2 + if len(b) >= 8 { + ac += uint64(binary.BigEndian.Uint32(b[:4])) + ac += uint64(binary.BigEndian.Uint32(b[4:8])) + b = b[8:] } - if n == 1 { - ac += uint64(b[i]) << 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 } |