static char rcsid[] = "$Id: rfc1738.c,v 2.2 1997/06/12 22:26:27 sxw Exp $";
/*
 *  rfc1738.c - code to comply with RFC 1738 
 *
 *  DEBUG: none
 *  AUTHOR: Harvest derived
 *
 *  Harvest Indexer http://www.tardis.ed.ac.uk/harvest/
 *  ---------------------------------------------------
 *
 *  The Harvest Indexer is a continued development of code developed by
 *  the Harvest Project. Development is carried out by numerous individuals
 *  in the Internet community, and is not officially connected with the
 *  original Harvest Project or its funding sources.
 * 
 *  Please mail harvest@tardis.ed.ac.uk if you are interested in participating
 *  in the development effort.
 *
 *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
/*  ----------------------------------------------------------------------
 *  Copyright (c) 1994, 1995.  All rights reserved.
 *  
 *    The Harvest software was developed by the Internet Research Task
 *    Force Research Group on Resource Discovery (IRTF-RD):
 *  
 *          Mic Bowman of Transarc Corporation.
 *          Peter Danzig of the University of Southern California.
 *          Darren R. Hardy of the University of Colorado at Boulder.
 *          Udi Manber of the University of Arizona.
 *          Michael F. Schwartz of the University of Colorado at Boulder.
 *          Duane Wessels of the University of Colorado at Boulder.
 *  
 *    This copyright notice applies to software in the Harvest
 *    ``src/'' directory only.  Users should consult the individual
 *    copyright notices in the ``components/'' subdirectories for
 *    copyright information about other software bundled with the
 *    Harvest source code distribution.
 *  
 *  TERMS OF USE
 *    
 *    The Harvest software may be used and re-distributed without
 *    charge, provided that the software origin and research team are
 *    cited in any use of the system.  Most commonly this is
 *    accomplished by including a link to the Harvest Home Page
 *    (http://harvest.cs.colorado.edu/) from the query page of any
 *    Broker you deploy, as well as in the query result pages.  These
 *    links are generated automatically by the standard Broker
 *    software distribution.
 *    
 *    The Harvest software is provided ``as is'', without express or
 *    implied warranty, and with no support nor obligation to assist
 *    in its use, correction, modification or enhancement.  We assume
 *    no liability with respect to the infringement of copyrights,
 *    trade secrets, or any patents, and are not responsible for
 *    consequential damages.  Proper use of the Harvest software is
 *    entirely the responsibility of the user.
 *  
 *  DERIVATIVE WORKS
 *  
 *    Users may make derivative works from the Harvest software, subject 
 *    to the following constraints:
 *  
 *      - You must include the above copyright notice and these 
 *        accompanying paragraphs in all forms of derivative works, 
 *        and any documentation and other materials related to such 
 *        distribution and use acknowledge that the software was 
 *        developed at the above institutions.
 *  
 *      - You must notify IRTF-RD regarding your distribution of 
 *        the derivative work.
 *  
 *      - You must clearly notify users that your are distributing 
 *        a modified version and not the original Harvest software.
 *  
 *      - Any derivative product is also subject to these copyright 
 *        and use restrictions.
 *  
 *    Note that the Harvest software is NOT in the public domain.  We
 *    retain copyright, as specified above.
 *  
 *  HISTORY OF FREE SOFTWARE STATUS
 *  
 *    Originally we required sites to license the software in cases
 *    where they were going to build commercial products/services
 *    around Harvest.  In June 1995 we changed this policy.  We now
 *    allow people to use the core Harvest software (the code found in
 *    the Harvest ``src/'' directory) for free.  We made this change
 *    in the interest of encouraging the widest possible deployment of
 *    the technology.  The Harvest software is really a reference
 *    implementation of a set of protocols and formats, some of which
 *    we intend to standardize.  We encourage commercial
 *    re-implementations of code complying to this set of standards.  
 *  
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "util.h"
#define BIG_BUFSIZ (BUFSIZ * 8)

/*  
 *  RFC 1738 defines that these characters should be escaped, as well
 *  any non-US-ASCII character or anything between 0x00 - 0x1F.
 */
static char rfc1738_unsafe_chars[] =
{
    (char) 0x3C,		/* < */
    (char) 0x3E,		/* > */
    (char) 0x22,		/* " */
    (char) 0x23,		/* # */
    (char) 0x25,		/* % */
    (char) 0x7B,		/* { */
    (char) 0x7D,		/* } */
    (char) 0x7C,		/* | */
    (char) 0x5C,		/* \ */
    (char) 0x5E,		/* ^ */
    (char) 0x7E,		/* ~ */
    (char) 0x5B,		/* [ */
    (char) 0x5D,		/* ] */
    (char) 0x60,		/* ` */
    (char) 0x27,		/* ' */
    (char) 0x20			/* space */
};

/*
 *  rfc1738_escape - Returns a static buffer contains the RFC 1738 
 *  compliant, escaped version of the given url.
 */
char *rfc1738_escape(url)
     char *url;
{
	static char buf[BIG_BUFSIZ];
	char *p, *q;
	int i, do_escape;

	for (p = url, q = &buf[0]; *p != '\0' && q<&buf[0]+BIG_BUFSIZ-1; 
	     p++, q++) {
		do_escape = 0;

		/* RFC 1738 defines these chars as unsafe */
		for (i = 0; i < sizeof(rfc1738_unsafe_chars); i++) {
			if (*p == rfc1738_unsafe_chars[i]) {
				do_escape = 1;
				break;
			}
		}
		/* RFC 1738 says any control chars (0x00-0x1F) are encoded */
		if (*p <= (char) 0x1F) {
			do_escape = 1;
		}
		/* RFC 1738 says 0x7f is encoded */
		if (*p == (char) 0x7F) {
			do_escape = 1;
		}
		/* RFC 1738 says any non-US-ASCII are encoded */
		if ((*p >= (char) 0x80) && (*p <= (char) 0xFF)) {
			do_escape = 1;
		}
		/* Do the triplet encoding, or just copy the char */
		if (do_escape == 1) {
			(void) sprintf(q, "%%%02x", (unsigned char) *p);
			q += sizeof(char) * 2;
		} else {
			*q = *p;
		}
	}
	*q = '\0';
	return (buf);
}

/*
 *  rfc1738_unescape() - Converts escaped characters (%xy numbers) in 
 *  given the string.  %% is a %. %ab is the 8-bit hexadecimal number "ab"
 *  Adapted to cope with single %s and with invalid %ab's
 */
void rfc1738_unescape(s)
     char *s;
{
	char hexnum[3];
	int i, j;		/* i is write, j is read */
	unsigned int x;

	for (i = j = 0; s[j]; i++, j++) {
		s[i] = s[j];
		if (s[i] == '%' && s[j+1]!='\0' && s[j+2]!='\0' &&
		    isxdigit(s[j+1]) && isxdigit(s[j+2])) {
			hexnum[0] = s[++j];
			if (hexnum[0] != '%') {
				hexnum[1] = s[++j];
				hexnum[2] = '\0';
				sscanf(hexnum, "%x", &x);
				s[i] = (char) (0x0ff & x);
			} else {
				s[i] = '%';
			}
		}
	}
	s[i] = '\0';
}
