src/core/base16.c

   1 /*
   2  * Copyright (C) 2010 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA.
  18  *
  19  * You can also choose to distribute this program under the terms of
  20  * the Unmodified Binary Distribution Licence (as given in the file
  21  * COPYING.UBDL), provided that you have satisfied its requirements.
  22  */
  23
  24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  25
  26 #include <stdint.h>
  27 #include <stdio.h>
  28 #include <errno.h>
  29 #include <assert.h>
  30 #include <ipxe/string.h>
  31 #include <ipxe/vsprintf.h>
  32 #include <ipxe/base16.h>
  33
  34 /** @file
  35  *
  36  * Base16 encoding
  37  *
  38  */
  39
  40 /**
  41  * Encode hexadecimal string (with optional byte separator character)
  42  *
  43  * @v separator         Byte separator character, or 0 for no separator
  44  * @v raw               Raw data
  45  * @v raw_len           Length of raw data
  46  * @v data              Buffer
  47  * @v len               Length of buffer
  48  * @ret len             Encoded length
  49  */
  50 size_t hex_encode ( char separator, const void *raw, size_t raw_len,
  51                     char *data, size_t len ) {
  52         const uint8_t *bytes = raw;
  53         const char delimiter[2] = { separator, '\0' };
  54         size_t used = 0;
  55         unsigned int i;
  56
  57         if ( len )
  58                 data[0] = 0; /* Ensure that a terminating NUL exists */
  59         for ( i = 0 ; i < raw_len ; i++ ) {
  60                 used += ssnprintf ( ( data + used ), ( len - used ),
  61                                     "%s%02x", ( used ? delimiter : "" ),
  62                                     bytes[i] );
  63         }
  64         return used;
  65 }
  66
  67 /**
  68  * Decode hexadecimal string (with optional byte separator character)
  69  *
  70  * @v separator         Byte separator character, or 0 for no separator
  71  * @v encoded           Encoded string
  72  * @v data              Buffer
  73  * @v len               Length of buffer
  74  * @ret len             Length of data, or negative error
  75  */
  76 int hex_decode ( char separator, const char *encoded, void *data, size_t len ) {
  77         uint8_t *out = data;
  78         unsigned int count = 0;
  79         unsigned int sixteens;
  80         unsigned int units;
  81
  82         while ( *encoded ) {
  83
  84                 /* Check separator, if applicable */
  85                 if ( count && separator && ( ( *(encoded++) != separator ) ) )
  86                         return -EINVAL;
  87
  88                 /* Extract digits.  Note that either digit may be NUL,
  89                  * which would be interpreted as an invalid value by
  90                  * digit_value(); there is therefore no need for an
  91                  * explicit end-of-string check.
  92                  */
  93                 sixteens = digit_value ( *(encoded++) );
  94                 if ( sixteens >= 16 )
  95                         return -EINVAL;
  96                 units = digit_value ( *(encoded++) );
  97                 if ( units >= 16 )
  98                         return -EINVAL;
  99
 100                 /* Store result */
 101                 if ( count < len )
 102                         out[count] = ( ( sixteens << 4 ) | units );
 103                 count++;
 104
 105         }
 106         return count;
 107 }