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112 lines
3.8 KiB
C
112 lines
3.8 KiB
C
/*
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Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
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This file is part of 0MQ.
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0MQ is free software; you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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0MQ is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "zmq_z85.h"
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/* Z85 codec, taken from 0MQ RFC project, implements RFC32 Z85 encoding */
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/* Maps base 256 to base 85 */
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static char encoder [85 + 1] = {
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"0123456789" "abcdefghij" "klmnopqrst" "uvwxyzABCD"
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"EFGHIJKLMN" "OPQRSTUVWX" "YZ.-:+=^!/" "*?&<>()[]{"
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"}@%$#"
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};
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/* Maps base 85 to base 256 */
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/* We chop off lower 32 and higher 128 ranges */
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static uint8_t decoder [96] = {
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0x00, 0x44, 0x00, 0x54, 0x53, 0x52, 0x48, 0x00,
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0x4B, 0x4C, 0x46, 0x41, 0x00, 0x3F, 0x3E, 0x45,
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0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x40, 0x00, 0x49, 0x42, 0x4A, 0x47,
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0x51, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A,
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0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32,
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0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A,
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0x3B, 0x3C, 0x3D, 0x4D, 0x00, 0x4E, 0x43, 0x00,
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0x00, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10,
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0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
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0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20,
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0x21, 0x22, 0x23, 0x4F, 0x00, 0x50, 0x00, 0x00
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};
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/* -------------------------------------------------------------------------- */
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/* Encode a binary frame as a string; destination string MUST be at least */
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/* size * 5 / 4 bytes long plus 1 byte for the null terminator. Returns */
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/* dest. Size must be a multiple of 4. */
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char *zmq_z85_encode (char *dest, uint8_t *data, size_t size)
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{
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if (size % 4 != 0)
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return NULL; /* !assert */
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unsigned int char_nbr = 0;
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unsigned int byte_nbr = 0;
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uint32_t value = 0;
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while (byte_nbr < size) {
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/* Accumulate value in base 256 (binary) */
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value = value * 256 + data [byte_nbr++];
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if (byte_nbr % 4 == 0) {
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/* Output value in base 85 */
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unsigned int divisor = 85 * 85 * 85 * 85;
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while (divisor) {
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dest [char_nbr++] = encoder [value / divisor % 85];
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divisor /= 85;
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}
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value = 0;
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}
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}
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if (char_nbr != size * 5 / 4)
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return NULL; /* !assert */
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dest [char_nbr] = 0;
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return dest;
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}
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/* -------------------------------------------------------------------------- */
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/* Decode an encoded string into a binary frame; dest must be at least */
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/* strlen (string) * 4 / 5 bytes long. Returns dest. strlen (string) */
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/* must be a multiple of 5. */
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uint8_t *zmq_z85_decode (uint8_t *dest, char *string)
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{
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if (strlen (string) % 5 != 0)
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return NULL; /* !assert */
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unsigned int byte_nbr = 0;
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unsigned int char_nbr = 0;
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uint32_t value = 0;
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size_t string_len = strlen (string);
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while (char_nbr < string_len) {
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/* Accumulate value in base 85 */
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value = value * 85 + decoder [(uint8_t) string [char_nbr++] - 32];
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if (char_nbr % 5 == 0) {
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/* Output value in base 256 */
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unsigned int divisor = 256 * 256 * 256;
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while (divisor) {
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dest [byte_nbr++] = value / divisor % 256;
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divisor /= 256;
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}
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value = 0;
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}
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}
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if (byte_nbr != strlen (string) * 4 / 5)
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return NULL; /* !assert */
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return dest;
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}
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