/*
 * $Id: rfc1738.c,v 1.5.62.1 2003/06/19 02:13:57 squidadm Exp $
 *
 * DEBUG:
 * AUTHOR: Harvest Derived
 *
 * SQUID Web Proxy Cache          http://www.squid-cache.org/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from
 *  the Internet community; see the CONTRIBUTORS file for full
 *  details.   Many organizations have provided support for Squid's
 *  development; see the SPONSORS file for full details.  Squid is
 *  Copyrighted (C) 2001 by the Regents of the University of
 *  California; see the COPYRIGHT file for full details.  Squid
 *  incorporates software developed and/or copyrighted by other
 *  sources; 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 rfc1738_unsafe_chars[] =
{
    (char) 0x3C,               /* < */
    (char) 0x3E,               /* > */
    (char) 0x22,               /* " */
    (char) 0x23,               /* # */
#if 0                          /* done in code */
    (char) 0x25,               /* % */
#endif
    (char) 0x7B,               /* { */
    (char) 0x7D,               /* } */
    (char) 0x7C,               /* | */
    (char) 0x5C,               /* \ */
    (char) 0x5E,               /* ^ */
    (char) 0x7E,               /* ~ */
    (char) 0x5B,               /* [ */
    (char) 0x5D,               /* ] */
    (char) 0x60,               /* ` */
    (char) 0x27,               /* ' */
    (char) 0x20                        /* space */
};

static char rfc1738_reserved_chars[] =
{
    (char) 0x3b,               /* ; */
    (char) 0x2f,               /* / */
    (char) 0x3f,               /* ? */
    (char) 0x3a,               /* : */
    (char) 0x40,               /* @ */
    (char) 0x3d,               /* = */
    (char) 0x26                        /* & */
};

/*
 *  rfc1738_escape - Returns a static buffer contains the RFC 1738
 *  compliant, escaped version of the given url.
 */
static char *
rfc1738_do_escape(const char *url, int encode_reserved)
{
    static char *buf;
    static size_t bufsize = 0;
    const char *p;
    char *q;
    unsigned int i, do_escape;

    if (buf == NULL || strlen(url) * 3 > bufsize) {
       xfree(buf);
       bufsize = strlen(url) * 3 + 1;
       buf = (char *) xcalloc(bufsize, 1);
    }
    for (p = url, q = buf; *p != '\0'; 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;
           }
       }
       /* Handle % separately */
       if (encode_reserved >= 0 && *p == '%')
           do_escape = 1;
       /* RFC 1738 defines these chars as reserved */
       for (i = 0; i < sizeof(rfc1738_reserved_chars) && encode_reserved > 0; i++) {
           if (*p == rfc1738_reserved_chars[i]) {
               do_escape = 1;
               break;
           }
       }
       /* RFC 1738 says any control chars (0x00-0x1F) are encoded */
       if ((unsigned char) *p <= (unsigned 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 (((unsigned char) *p >= (unsigned char) 0x80)) {
           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, "%%%02x", (unsigned char) *p);
           q += sizeof(char) * 2;
       } else {
           *q = *p;
       }
    }
    *q = '\0';
    return (buf);
}

/*
 * rfc1738_escape - Returns a static buffer that contains the RFC
 * 1738 compliant, escaped version of the given url.
 */
char *
rfc1738_escape(const char *url)
{
    return rfc1738_do_escape(url, 0);
}

/*
 * rfc1738_escape_unescaped - Returns a static buffer that contains
 * the RFC 1738 compliant, escaped version of the given url.
 */
char *
rfc1738_escape_unescaped(const char *url)
{
    return rfc1738_do_escape(url, -1);
}

/*
 * rfc1738_escape_part - Returns a static buffer that contains the
 * RFC 1738 compliant, escaped version of the given url segment.
 */
char *
rfc1738_escape_part(const char *url)
{
    return rfc1738_do_escape(url, 1);
}

/*
 *  rfc1738_unescape() - Converts escaped characters (%xy numbers) in
 *  given the string.  %% is a %. %ab is the 8-bit hexadecimal number "ab"
 */
void
rfc1738_unescape(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] != '%')
           continue;
       if (s[j + 1] == '%') {  /* %% case */
           j++;
           continue;
       }
       if (s[j + 1] && s[j + 2]) {
           hexnum[0] = s[j + 1];
           hexnum[1] = s[j + 2];
           hexnum[2] = '\0';
           if (1 == sscanf(hexnum, "%x", &x)) {
               s[i] = (char) (0x0ff & x);
               j += 2;
           }
       }
    }
    s[i] = '\0';
}
