urlcode.c

/** urlcode.c ---
 *
 * Copyright (C) 2010 PhoeniX11 Kayo
 *
 * Author: PhoeniX11 Kayo <phoenix11@users.sf.net>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "urlcode.h"

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

/* Converts a hex character to its integer value */
static char from_hex(char ch) {
  return isdigit(ch) ? ch-'0' : tolower(ch)-'a'+10;
}

/* Converts an integer value to its hex character*/
static char to_hex(char code) {
  static char hex[]="0123456789abcdef";
  return hex[code & 15];
}

/* Returns a url-encoded version of str */
/* IMPORTANT: be sure to free() the returned string after use */
char *url_encode(const char *str) {
  const char *pstr = str;
  char *buf = malloc(strlen(str) * 3 + 1), *pbuf = buf;
  while (*pstr) {
    if (isalnum(*pstr) || *pstr == '-' || *pstr == '_' || *pstr == '.' || *pstr == '~') 
      *pbuf++ = *pstr;
    else if (*pstr == ' ') 
      *pbuf++ = '+';
    else 
      *pbuf++ = '%', *pbuf++ = to_hex(*pstr >> 4), *pbuf++ = to_hex(*pstr & 15);
    pstr++;
  }
  *pbuf = '\0';
  return buf;
}

/* Returns a url-decoded version of str */
/* IMPORTANT: be sure to free() the returned string after use */
char *url_decode(const char *str)
{
  const char *pstr = str;
  char *buf = malloc(strlen(str) + 1), *pbuf = buf;
  while (*pstr)
  {
    switch (*pstr)
    {
    case '%':
      if (pstr[1] && pstr[2])
      {
        *pbuf++ = from_hex(pstr[1]) << 4 | from_hex(pstr[2]);
        pstr += 2;
      }
      break;

    case '+':
      *pbuf++ = ' ';
      break;

    default:
      *pbuf++ = *pstr;
      break;
    }
    pstr++;
  }
  *pbuf = '\0';
  return buf;
}

void url_free(char *str)
{
  free(str);
}