lib/roken/hex.c

   1 /*
   2  * Copyright (c) 2004-2005 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34
  35 #include <config.h>
  36 #include "roken.h"
  37 #include <ctype.h>
  38 #include "hex.h"
  39
  40 const static char hexchar[] = "0123456789ABCDEF";
  41
  42 static int
  43 pos(char c)
  44 {
  45     const char *p;
  46     c = toupper((unsigned char)c);
  47     for (p = hexchar; *p; p++)
  48         if (*p == c)
  49             return p - hexchar;
  50     return -1;
  51 }
  52
  53 ROKEN_LIB_FUNCTION ssize_t ROKEN_LIB_CALL
  54 hex_encode(const void *data, size_t size, char **str)
  55 {
  56     const unsigned char *q = data;
  57     size_t i;
  58     char *p;
  59
  60     /* check for overflow */
  61     if (size * 2 < size) {
  62         *str = NULL;
  63         return -1;
  64     }
  65
  66     p = malloc(size * 2 + 1);
  67     if (p == NULL) {
  68         *str = NULL;
  69         return -1;
  70     }
  71
  72     for (i = 0; i < size; i++) {
  73         p[i * 2] = hexchar[(*q >> 4) & 0xf];
  74         p[i * 2 + 1] = hexchar[*q & 0xf];
  75         q++;
  76     }
  77     p[i * 2] = '\0';
  78     *str = p;
  79
  80     return i * 2;
  81 }
  82
  83 ROKEN_LIB_FUNCTION ssize_t ROKEN_LIB_CALL
  84 hex_decode(const char *str, void *data, size_t len)
  85 {
  86     size_t l;
  87     unsigned char *p = data;
  88     size_t i;
  89
  90     l = strlen(str);
  91
  92     /* check for overflow, same as (l+1)/2 but overflow safe */
  93     if ((l/2) + (l&1) > len)
  94         return -1;
  95
  96     i = 0;
  97     if (l & 1) {
  98         p[0] = pos(str[0]);
  99         str++;
 100         p++;
 101     }
 102     for (i = 0; i < l / 2; i++)
 103         p[i] = pos(str[i * 2]) << 4 | pos(str[(i * 2) + 1]);
 104     return i + (l & 1);
 105 }