Base64cp » История » Версия 3
Андрей Волков, 2013-06-03 19:46
| 1 | 2 | Андрей Волков | h1. Передача бинарных файлов текстом |
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| 2 | 1 | Андрей Волков | |
| 3 | 2 | Андрей Волков | h2. Декодировщик средствами bash |
| 4 | |||
| 5 | *base64decode.sh* |
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| 6 | |||
| 7 | 1 | Андрей Волков | <pre> |
| 8 | #!/bin/bash |
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| 9 | |||
| 10 | # Base64 decoding routine written entirely in bash, with no external dependencies. |
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| 11 | # |
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| 12 | # Usage: |
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| 13 | # base64decode < input > output |
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| 14 | # |
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| 15 | # This code is absurly inefficient; it runs aproximately 12,000 times slower than |
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| 16 | # the perl-based decoder. The difference is that this code doesn't require you to |
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| 17 | # install any external programs, which may be important in some cases. |
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| 18 | # |
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| 19 | # To decode using perl instead, use the following: |
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| 20 | # |
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| 21 | # base64decode() { |
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| 22 | # perl -e 'use MIME::Base64 qw(decode_base64);$/=undef;print decode_base64(<>);' |
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| 23 | # } |
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| 24 | # |
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| 25 | |||
| 26 | base64decode() { |
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| 27 | L=0 |
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| 28 | A=0 |
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| 29 | P=0 |
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| 30 | while read -n1 C ; do |
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| 31 | printf -v N %i \'"$C" |
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| 32 | if (( $N == 61 )) ; then |
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| 33 | P=$(( $P + 1 )) # = (padding) |
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| 34 | V=0 |
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| 35 | elif (( $N == 43 )) ; then |
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| 36 | V=62 # + |
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| 37 | elif (( $N == 47 )) ; then |
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| 38 | V=63 # / |
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| 39 | elif (( $N < 48 )) ; then |
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| 40 | continue |
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| 41 | elif (( $N < 58 )) ; then |
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| 42 | V=$(( $N + 4 )) # -48 + 52 (0-9) |
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| 43 | elif (( $N < 65 )) ; then |
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| 44 | continue |
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| 45 | elif (( $N < 91 )) ; then |
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| 46 | V=$(( $N - 65 )) # -65 + 0 (A-Z) |
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| 47 | elif (( $N < 97 )) ; then |
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| 48 | continue |
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| 49 | elif (( $N < 123 )) ; then |
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| 50 | V=$(( $N - 71 )) # -97 + 26 (a-z) |
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| 51 | else |
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| 52 | continue |
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| 53 | fi |
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| 54 | |||
| 55 | A=$(( ($A << 6) | $V )) |
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| 56 | L=$(( $L + 1 )) |
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| 57 | |||
| 58 | if [ $L == 4 ] ; then |
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| 59 | printf -v X "%x" $(( ($A >> 16) & 0xFF )) |
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| 60 | printf "\x$X" |
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| 61 | if (( $P < 2 )) ; then |
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| 62 | printf -v X "%x" $(( ($A >> 8) & 0xFF )) |
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| 63 | printf "\x$X" |
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| 64 | fi |
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| 65 | if (( $P == 0 )) ; then |
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| 66 | printf -v X "%x" $(( $A & 0xFF )) |
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| 67 | printf "\x$X" |
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| 68 | fi |
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| 69 | A=0 |
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| 70 | L=0 |
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| 71 | P=0 |
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| 72 | fi |
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| 73 | done |
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| 74 | } |
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| 75 | |||
| 76 | 2 | Андрей Волков | base64decode |
| 77 | 1 | Андрей Волков | </pre> |
| 78 | 3 | Андрей Волков | |
| 79 | Прием файла |
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| 80 | |||
| 81 | read -d : data |
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| 82 | |||
| 83 | Вставляем текст и нажимаем ":" |
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| 84 | |||
| 85 | echo "${data}" > file.b64 |
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| 86 | |||
| 87 | . base64decode.sh < file.b64 > file.bin |