urldecode.cpp

/* from 
http://www.oreillynet.com/pub/a/network/excerpt/spcookbook_chap03/index2.html

$Id: urldecode.cpp,v 1.3 2008/04/20 03:03:06 laffer1 Exp $
*/

#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#include "urldecode.h"

#define SPC_BASE16_TO_10(x) (((x) >= '0' && (x) <= '9') ? ((x) - '0') : \
                             (toupper((x)) - 'A' + 10))


/**
*	spc_decode_url
*       Covert funky mime encoded characters into real ascii
*      @note returns dynamic memory.. use free
*/
char *spc_decode_url( const char *url, size_t *nbytes ) 
{
    char       *out, *ptr;
    const char *c;

    if (!(out = ptr = strdup(url))) 
        return 0;

    for (c = url;  *c;  c++) 
    {
        if (*c != '%' || !isxdigit(c[1]) || !isxdigit(c[2])) 
           *ptr++ = *c;
        else 
        {
            *ptr++ = (SPC_BASE16_TO_10(c[1]) * 16) + (SPC_BASE16_TO_10(c[2]));
            c += 2;
        }
    }
    *ptr = 0;
    if (nbytes) 
        *nbytes = (ptr - out); /* does not include null byte */
 
  return out;
}