daemon/escape.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * LADI Session Handler (ladish)
   4  *
   5  * Copyright (C) 2009 Nedko Arnaudov <nedko@arnaudov.name>
   6  *
   7  **************************************************************************
   8  * This file contains implementation of the escape helper functions
   9  **************************************************************************
  10  *
  11  * LADI Session Handler is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * LADI Session Handler is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with LADI Session Handler. If not, see <http://www.gnu.org/licenses/>
  23  * or write to the Free Software Foundation, Inc.,
  24  * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  25  */
  26
  27 #include "escape.h"
  28
  29 static char hex_digits[] = "0123456789ABCDEF";
  30
  31 #define HEX_TO_INT(hexchar) ((hexchar) <= '9' ? hexchar - '0' : 10 + (hexchar - 'A'))
  32
  33 void escape(const char ** src_ptr, char ** dst_ptr)
  34 {
  35   const char * src;
  36   char * dst;
  37
  38   src = *src_ptr;
  39   dst = *dst_ptr;
  40
  41   while (*src != 0)
  42   {
  43     switch (*src)
  44     {
  45     case '/':               /* used as separator for address components */
  46     case '<':               /* invalid attribute value char (XML spec) */
  47     case '&':               /* invalid attribute value char (XML spec) */
  48     case '"':               /* we store attribute values in double quotes - invalid attribute value char (XML spec) */
  49     case '\'':
  50     case '>':
  51     case '%':
  52       dst[0] = '%';
  53       dst[1] = hex_digits[*src >> 4];
  54       dst[2] = hex_digits[*src & 0x0F];
  55       dst += 3;
  56       src++;
  57       break;
  58     default:
  59       *dst++ = *src++;
  60     }
  61   }
  62
  63   *src_ptr = src;
  64   *dst_ptr = dst;
  65 }
  66
  67 size_t unescape(const char * src, size_t src_len, char * dst)
  68 {
  69   size_t dst_len;
  70
  71   dst_len = 0;
  72
  73   while (src_len)
  74   {
  75     if (src_len >= 3 &&
  76         src[0] == '%' &&
  77         ((src[1] >= '0' && src[1] <= '9') ||
  78          (src[1] >= 'A' && src[1] <= 'F')) &&
  79         ((src[2] >= '0' && src[2] <= '9') ||
  80          (src[2] >= 'A' && src[2] <= 'F')))
  81     {
  82       *dst = (HEX_TO_INT(src[1]) << 4) | HEX_TO_INT(src[2]);
  83       //lash_info("unescaping %c%c%c to '%c'", src[0], src[1], src[2], *dst);
  84       src_len -= 3;
  85       src += 3;
  86     }
  87     else
  88     {
  89       *dst = *src;
  90       src_len--;
  91       src++;
  92     }
  93     dst++;
  94     dst_len++;
  95   }
  96
  97   return dst_len;
  98 }