/*
 * $Id: rfc1738.c,v 1.2 2000/10/21 15:16:11 hno Exp $
 *
 * DEBUG: 
 * AUTHOR: Harvest Derived
 *
 * SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from the
 *  Internet community.  Development is led by Duane Wessels of the
 *  National Laboratory for Applied Network Research and funded by the
 *  National Science Foundation.  Squid is Copyrighted (C) 1998 by
 *  the Regents of the University of California.  Please see the
 *  COPYRIGHT file for full details.  Squid incorporates software
 *  developed and/or copyrighted by other sources.  Please see the
 *  CREDITS file for full details.
 *
 *  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 of the License, 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; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

#include "config.h"

#if HAVE_STDIO_H
#include <stdio.h>
#endif
#if HAVE_STRING_H
#include <string.h>
#endif

#include "util.h"
#include "snprintf.h"

/*  
 *  RFC 1738 defines that these characters should be escaped, as well
 *  any non-US-ASCII character or anything between 0x00 - 0x1F.
 */
static char htmlstandardentities[] =
{
    (char) 0x3C,		/* < */
    (char) 0x3E,		/* > */
    (char) 0x22,		/* " */
    (char) 0x26			/* & */
};

/*
 *  html_do_quote - Returns a static buffer containing the quoted 
 *  string.
 */
static char *
html_do_quote(const char *string)
{
    static char *buf;
    static size_t bufsize = 0;
    const char *p;
    char *q;
    int i, do_escape;

    if (buf == NULL || strlen(string) * 6 > bufsize) {
	xfree(buf);
	bufsize = strlen(string) * 6 + 1;
	buf = xcalloc(bufsize, 1);
    }
    for (p = string, q = buf; *p != '\0'; p++, q++) {
	do_escape = 0;

	/* These are HTML Entities that must be quoted to display safelu */
	for (i = 0; i < sizeof(htmlstandardentities); i++) {
	    if (*p == htmlstandardentities[i]) {
		do_escape = 1;
		break;
	    }
	}
	/* HTML doesn't require control chars to be quoted... but it seems sensible */
	if ((unsigned char) *p <= (unsigned char) 0x1F) {
	    do_escape = 1;
	}
	/* Do the triplet encoding, or just copy the char */
	/* note: we do not need snprintf here as q is appropriately
	 * allocated - KA */

	if (do_escape == 1) {
	    (void) sprintf(q, "&#%03d;", (unsigned char) *p);
	    q += sizeof(char) * 5;
	} else {
	    *q = *p;
	}
    }
    *q = '\0';
    return (buf);
}

/*
 * htmlquote - Returns a static buffer that contains the html 4
 * compliant, quoted version of the given string;
 */
char *
html_quote(const char *string)
{
    return html_do_quote(string);
}