daemon/escape.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * LADI Session Handler (ladish)
   4  *
   5  * Copyright (C) 2009, 2010 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, unsigned int flags)
  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 '\'':
  47     case '>':
  48     case '%':
  49       if ((flags & LADISH_ESCAPE_FLAG_OTHER) == 0)
  50       {
  51         break;
  52       }
  53       /* fall through intentionally, some compilers are parsing comments */
  54     case '<':               /* invalid attribute value char (XML spec) */
  55     case '&':               /* invalid attribute value char (XML spec) */
  56     case '"':               /* we store attribute values in double quotes - invalid attribute value char (XML spec) */
  57       if ((flags & LADISH_ESCAPE_FLAG_XML_ATTR) == 0)
  58       {
  59         break;
  60       }
  61       dst[0] = '%';
  62       dst[1] = hex_digits[*src >> 4];
  63       dst[2] = hex_digits[*src & 0x0F];
  64       dst += 3;
  65       src++;
  66       continue;
  67     }
  68
  69     *dst++ = *src++;
  70   }
  71
  72   *src_ptr = src;
  73   *dst_ptr = dst;
  74 }
  75
  76 void escape_simple(const char * src_ptr, char * dst_ptr, unsigned int flags)
  77 {
  78   escape(&src_ptr, &dst_ptr, flags);
  79   *dst_ptr = 0;
  80 }
  81
  82 size_t unescape(const char * src, size_t src_len, char * dst)
  83 {
  84   size_t dst_len;
  85
  86   dst_len = 0;
  87
  88   while (src_len)
  89   {
  90     if (src_len >= 3 &&
  91         src[0] == '%' &&
  92         ((src[1] >= '0' && src[1] <= '9') ||
  93          (src[1] >= 'A' && src[1] <= 'F')) &&
  94         ((src[2] >= '0' && src[2] <= '9') ||
  95          (src[2] >= 'A' && src[2] <= 'F')))
  96     {
  97       *dst = (HEX_TO_INT(src[1]) << 4) | HEX_TO_INT(src[2]);
  98       //lash_info("unescaping %c%c%c to '%c'", src[0], src[1], src[2], *dst);
  99       src_len -= 3;
 100       src += 3;
 101     }
 102     else
 103     {
 104       *dst = *src;
 105       src_len--;
 106       src++;
 107     }
 108     dst++;
 109     dst_len++;
 110   }
 111
 112   return dst_len;
 113 }
 114
 115 void unescape_simple(char * buffer)
 116 {
 117   unescape(buffer, strlen(buffer) + 1, buffer);
 118 }
 119
 120 char * unescape_dup(const char * src)
 121 {
 122   size_t len;
 123   char * dst;
 124
 125   len = strlen(src) + 1;
 126
 127   dst = malloc(len);
 128   if (dst != NULL)
 129   {
 130     unescape(src, len, dst);
 131   }
 132
 133   return dst;
 134 }