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., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <stdint.h>
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24 #include <errno.h>
  25 #include <gpxe/base16.h>
  26
  27 /** @file
  28  *
  29  * Base16 encoding
  30  *
  31  */
  32
  33 /**
  34  * Base16-encode data
  35  *
  36  * @v raw               Raw data
  37  * @v len               Length of raw data
  38  * @v encoded           Buffer for encoded string
  39  *
  40  * The buffer must be the correct length for the encoded string.  Use
  41  * something like
  42  *
  43  *     char buf[ base16_encoded_len ( len ) + 1 ];
  44  *
  45  * (the +1 is for the terminating NUL) to provide a buffer of the
  46  * correct size.
  47  */
  48 void base16_encode ( const uint8_t *raw, size_t len, char *encoded ) {
  49         const uint8_t *raw_bytes = raw;
  50         char *encoded_bytes = encoded;
  51         size_t remaining = len;
  52
  53         for ( ; remaining-- ; encoded_bytes += 2 ) {
  54                 sprintf ( encoded_bytes, "%02x", *(raw_bytes++) );
  55         }
  56
  57         DBG ( "Base16-encoded to \"%s\":\n", encoded );
  58         DBG_HDA ( 0, raw, len );
  59         assert ( strlen ( encoded ) == base16_encoded_len ( len ) );
  60 }
  61
  62 /**
  63  * Base16-decode data
  64  *
  65  * @v encoded           Encoded string
  66  * @v raw               Raw data
  67  * @ret len             Length of raw data, or negative error
  68  *
  69  * The buffer must be large enough to contain the decoded data.  Use
  70  * something like
  71  *
  72  *     char buf[ base16_decoded_max_len ( encoded ) ];
  73  *
  74  * to provide a buffer of the correct size.
  75  */
  76 int base16_decode ( const char *encoded, uint8_t *raw ) {
  77         const char *encoded_bytes = encoded;
  78         uint8_t *raw_bytes = raw;
  79         char buf[3];
  80         char *endp;
  81         size_t len;
  82
  83         while ( encoded_bytes[0] ) {
  84                 if ( ! encoded_bytes[1] ) {
  85                         DBG ( "Base16-encoded string \"%s\" has invalid "
  86                               "length\n", encoded );
  87                         return -EINVAL;
  88                 }
  89                 memcpy ( buf, encoded_bytes, 2 );
  90                 buf[2] = '\0';
  91                 *(raw_bytes++) = strtoul ( buf, &endp, 16 );
  92                 if ( *endp != '\0' ) {
  93                         DBG ( "Base16-encoded string \"%s\" has invalid "
  94                               "byte \"%s\"\n", encoded, buf );
  95                         return -EINVAL;
  96                 }
  97                 encoded_bytes += 2;
  98         }
  99         len = ( raw_bytes - raw );
 100
 101         DBG ( "Base16-decoded \"%s\" to:\n", encoded );
 102         DBG_HDA ( 0, raw, len );
 103         assert ( len <= base16_decoded_max_len ( encoded ) );
 104
 105         return ( len );
 106 }