162 lines
4.7 KiB
C
162 lines
4.7 KiB
C
/*-
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* Copyright (c) 2013 Universitetet i Oslo
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id$
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <errno.h>
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#include <stdint.h>
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#include "oath.h"
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/* amount of space necessary to store base32-encoded data */
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#define base32_enclen(l) (((l + 4) / 5) * 8)
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/* maximum decoded length of base32-encoded data */
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#define base32_declen(l) (((l + 7) / 8) * 5)
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static const char b32 =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
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/*
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* Encode data in RFC 3548 base 32 representation. The target buffer must
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* have room for base32_enclen(len) characters and a terminating NUL.
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*/
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static int
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base32_enc(const uint8_t *in, size_t ilen, char *out, size_t *olen)
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{
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uint64_t bits;
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if (*olen <= base32_enclen(ilen))
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return (-1);
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*olen = 0;
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while (ilen >= 5) {
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bits = 0;
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bits = bits << 8 | in[0];
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bits = bits << 8 | in[1];
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bits = bits << 8 | in[2];
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bits = bits << 8 | in[3];
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bits = bits << 8 | in[4];
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ilen -= 5;
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in += 5;
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out[0] = b32[bits >> 5*7 & 0x1f];
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out[1] = b32[bits >> 5*6 & 0x1f];
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out[2] = b32[bits >> 5*5 & 0x1f];
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out[3] = b32[bits >> 5*4 & 0x1f];
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out[4] = b32[bits >> 5*3 & 0x1f];
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out[5] = b32[bits >> 5*2 & 0x1f];
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out[6] = b32[bits >> 5*1 & 0x1f];
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out[7] = b32[bits >> 5*0 & 0x1f];
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olen += 8;
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out += 8;
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}
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if (ilen > 0) {
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bits = 0;
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switch (ilen) {
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case 4:
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bits |= (uint64_t)in[3] << 8;
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case 3:
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bits |= (uint64_t)in[2] << 16;
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case 2:
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bits |= (uint64_t)in[1] << 24;
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case 1:
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bits |= (uint64_t)in[1] << 32;
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}
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out[0] = b32[bits >> 5*7 & 0x1f];
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out[1] = b32[bits >> 5*6 & 0x1f];
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out[2] = ilen > 1 ? b32[bits >> 5*5 & 0x1f] : '=';
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out[3] = ilen > 1 ? b32[bits >> 5*4 & 0x1f] : '=';
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out[4] = ilen > 2 ? b32[bits >> 5*3 & 0x1f] : '=';
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out[5] = ilen > 3 ? b32[bits >> 5*2 & 0x1f] : '=';
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out[6] = ilen > 3 ? b32[bits >> 5*1 & 0x1f] : '=';
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out[7] = '=';
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olen += 8;
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out += 8;
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}
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out[0] = '\0';
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return (0);
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}
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/*
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* Decode data in RFC 2548 base 32 representation, stopping at the
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* terminating NUL, the first invalid (non-base32, non-whitespace)
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* character or after len characters, whichever comes first.
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*
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* The olen argument is used by the caller to pass the size of the buffer
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* and by base32_dec() to return the amount of data successfully decoded.
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* If the buffer is too small, base32_dec() discards the excess data, but
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* returns the total amount.
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*/
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static int
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base32_dec(const char *in, size_t ilen, uint8_t *out, size_t *olen)
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{
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size_t len;
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uint64_t bits;
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int shift;
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for (len = 0, bits = 0, shift = 40; ilen && *in; --ilen, ++in) {
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if (*in == ' ' || *in == '\t' || *in == '\r' || *in == '\n') {
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continue;
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} else if (*in >= 'A' && *in <= 'Z') {
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shift -= 5;
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bits |= (uint64_t)(*in - 'A') << shift;
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} else if (*in >= 'a' && *in <= 'z') {
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shift -= 5;
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bits |= (uint64_t)(*in - 'a') << shift;
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} else if (*in >= '2' && *in <= '7') {
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shift -= 5;
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bits |= (uint64_t)(*in - '2' + 26) << shift;
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} else {
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*olen = 0;
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return (-1);
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}
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if (shift == 0) {
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if ((len += 5) <= *olen) {
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out[0] = (bits >> 32) & 0xff;
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out[1] = (bits >> 24) & 0xff;
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out[2] = (bits >> 16) & 0xff;
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out[3] = (bits >> 8) & 0xff;
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out[4] = bits & 0xff;
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out += 5;
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}
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bits = 0;
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shift = 40;
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}
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}
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if (len > *olen) {
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*olen = len;
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return (-1);
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}
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*olen = len;
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return (0);
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}
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