lib/html_quote.c

   1 /*
   2  * DEBUG:
   3  * AUTHOR: Robert Collins
   4  *
   5  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   6  * ----------------------------------------------------------
   7  *
   8  *  Squid is the result of efforts by numerous individuals from
   9  *  the Internet community; see the CONTRIBUTORS file for full
  10  *  details.   Many organizations have provided support for Squid's
  11  *  development; see the SPONSORS file for full details.  Squid is
  12  *  Copyrighted (C) 2001 by the Regents of the University of
  13  *  California; see the COPYRIGHT file for full details.  Squid
  14  *  incorporates software developed and/or copyrighted by other
  15  *  sources; see the CREDITS file for full details.
  16  *
  17  *  This program is free software; you can redistribute it and/or modify
  18  *  it under the terms of the GNU General Public License as published by
  19  *  the Free Software Foundation; either version 2 of the License, or
  20  *  (at your option) any later version.
  21  *
  22  *  This program is distributed in the hope that it will be useful,
  23  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25  *  GNU General Public License for more details.
  26  *
  27  *  You should have received a copy of the GNU General Public License
  28  *  along with this program; if not, write to the Free Software
  29  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  30  *
  31  */
  32
  33 #include "squid.h"
  34 #include "html_quote.h"
  35
  36 #if HAVE_STRING_H
  37 #include <string.h>
  38 #endif
  39
  40 /*
  41  *  HTML defines these characters as special entities that should be quoted.
  42  */
  43 static struct {
  44     unsigned char code;
  45     const char *quote;
  46 } htmlstandardentities[] =
  47
  48 {
  49     /* NOTE: The quoted form MUST not be larger than 6 character.
  50      * see close to the MemPool commend below
  51      */
  52     {
  53         '<', "&lt;"
  54     },
  55     {
  56         '>', "&gt;"
  57     },
  58     {
  59         '"', "&quot;"
  60     },
  61     {
  62         '&', "&amp;"
  63     },
  64     {
  65         '\'', "&#39;"
  66     },
  67     {
  68         0, NULL
  69     }
  70 };
  71
  72 /*
  73  *  html_do_quote - Returns a static buffer containing the quoted
  74  *  string.
  75  */
  76 char *
  77 html_quote(const char *string)
  78 {
  79     static char *buf;
  80     static size_t bufsize = 0;
  81     const char *src;
  82     char *dst;
  83     int i;
  84
  85     /* XXX This really should be implemented using a MemPool, but
  86      * MemPools are not yet available in lib...
  87      */
  88     if (buf == NULL || strlen(string) * 6 > bufsize) {
  89         xfree(buf);
  90         bufsize = strlen(string) * 6 + 1;
  91         buf = xcalloc(bufsize, 1);
  92     }
  93     for (src = string, dst = buf; *src; src++) {
  94         const char *escape = NULL;
  95         const unsigned char ch = *src;
  96
  97         /* Walk thru the list of HTML Entities that must be quoted to
  98          * display safely
  99          */
 100         for (i = 0; htmlstandardentities[i].code; i++) {
 101             if (ch == htmlstandardentities[i].code) {
 102                 escape = htmlstandardentities[i].quote;
 103                 break;
 104             }
 105         }
 106         /* Encode control chars just to be on the safe side, and make
 107          * sure all 8-bit characters are encoded to protect from buggy
 108          * clients
 109          */
 110         if (!escape && (ch <= 0x1F || ch >= 0x7f) && ch != '\n' && ch != '\r' && ch != '\t') {
 111             static char dec_encoded[7];
 112             snprintf(dec_encoded, sizeof dec_encoded, "&#%3d;", (int) ch);
 113             escape = dec_encoded;
 114         }
 115         if (escape) {
 116             /* Ok, An escaped form was found above. Use it */
 117             strncpy(dst, escape, 6);
 118             dst += strlen(escape);
 119         } else {
 120             /* Apparently there is no need to escape this character */
 121             *dst++ = ch;
 122         }
 123     }
 124     /* Nullterminate and return the result */
 125     *dst = '\0';
 126     return (buf);
 127 }