/*

 * Functions for RFC 3986 percent-encoding.

 *

 * NOTE:

 *

 * This file was originally imported from the Squid project but has been

 * significantly altered. The licence below is reproduced intact, but refers

 * to files in Squid's repository, not in Samba. See COPYING for the GPLv3

 * notice (being the later version mentioned below).

 */

/*

 * $Id$

 *

 * 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 "replace.h"

#include <talloc.h>

#include "lib/util/samba_util.h"

#define RFC1738_ENCODE 1

#define RFC1738_RESERVED 2

/*

 * According to RFC 1738, "$-_.+!*'()," are not reserved or unsafe, but as

 * that has been obsolete since 2004, we sm instead for RFC 3986, where:

 *

 *  reserved =    : / ? # [ ] @ ! $ & ' ( ) * + , ; =

 *  unreserved = ALPHA DIGIT - . _ ~

 *

 * and whatever is not in either of those are what RFC 1738 called "unsafe",

 * meaning that they should are canonically but not mandatorily escaped.

 *

 * Characters below 0x20 or above 0x7E are always encoded.

 */

static const unsigned char escapees[127] = {

  [' '] = RFC1738_ENCODE,

  ['"'] = RFC1738_ENCODE,

  ['%'] = RFC1738_ENCODE,

  ['<'] = RFC1738_ENCODE,

  ['>'] = RFC1738_ENCODE,

  ['\\'] = RFC1738_ENCODE,

  ['^'] = RFC1738_ENCODE,

  ['`'] = RFC1738_ENCODE,

  ['{'] = RFC1738_ENCODE,

  ['|'] = RFC1738_ENCODE,

  ['}'] = RFC1738_ENCODE,

  /* reserved : / ? # [ ] @ ! $ & ' ( ) * + , ; = */

  [':'] = RFC1738_RESERVED,

  ['/'] = RFC1738_RESERVED,

  ['?'] = RFC1738_RESERVED,

  ['#'] = RFC1738_RESERVED,

  ['['] = RFC1738_RESERVED,

  [']'] = RFC1738_RESERVED,

  ['@'] = RFC1738_RESERVED,

  ['!'] = RFC1738_RESERVED,

  ['$'] = RFC1738_RESERVED,

  ['&'] = RFC1738_RESERVED,

  ['\''] = RFC1738_RESERVED,

  ['('] = RFC1738_RESERVED,

  [')'] = RFC1738_RESERVED,

  ['*'] = RFC1738_RESERVED,

  ['+'] = RFC1738_RESERVED,

  [','] = RFC1738_RESERVED,

  [';'] = RFC1738_RESERVED,

  ['='] = RFC1738_RESERVED,

};

/*

 *  rfc1738_do_escape - fills a preallocated buffer with an escaped version of

 *  the given string.

 *

 *  For canonical escaping, mask should be RFC1738_ENCODE | RFC1738_RESERVED.

 *  For mandatory escaping, mask should be RFC1738_RESERVED.

 */

static char *

rfc1738_do_escape(char *buf, size_t bufsize,

      const char *url, size_t len, unsigned char mask)

{

  size_t i;

  size_t j = 0;

  for (i = 0; i < len; i++) {

    unsigned int c = (unsigned char) url[i];

    if (c > 126 || c < 32 || (escapees[c] & mask)) {

      if (j + 3 >= bufsize) {

        return NULL;

      }

      (void) snprintf(&buf[j], 4, "%%%02X", c);

      j += 3;

    } else {

      if (j + 1 >= bufsize) {

        return NULL;

      }

      buf[j] = c;

      j++;

    }

  }

  buf[j] = '\0';

  return buf;

}

/*

 * rfc1738_escape_part - Returns a talloced buffer that contains the RFC 3986

 * compliant, escaped version of the given url segment.

 */

char *

rfc1738_escape_part(TALLOC_CTX *mem_ctx, const char *url)

{

  size_t bufsize = 0;

  char *buf = NULL;

  size_t len = strlen(url);

  if (len >= SIZE_MAX / 3) {

    return NULL;

  }

  bufsize = len * 3 + 1;

  buf = talloc_array(mem_ctx, char, bufsize);

  if (buf == NULL) {

    return NULL;

  }

  talloc_set_name_const(buf, buf);

  return rfc1738_do_escape(buf, bufsize, url, len,

         RFC1738_ENCODE | RFC1738_RESERVED);

}

/*

 * rfc1738_unescape() - Converts url-escaped characters in the string.

 *

 * The two characters following a '%' in a string should be hex digits that

 * describe an encoded byte. For example, "%25" is hex 0x25 or '%' in ASCII;

 * this is the only way to include a % in the unescaped string. Any character

 * can be escaped, including plain letters (e.g. "%61" for "a"). Anything

 * other than 2 hex characters following the % is an error.

 *

 * The conversion is done in-place, which is always safe as unescapes can only

 * shorten the string.

 *

 * Returns a pointer to the end of the string (that is, the '\0' byte), or

 * NULL on error, at which point s is in an undefined state.

 *

 * Note that after `char *e = rfc_unescape(s)`, `strlen(s)` will not equal

 * `e - s` if s originally contained "%00". You might want to check for this.

 */

_PUBLIC_ char *rfc1738_unescape(char *s)

{

  size_t i, j;      /* i is write, j is read */

  for (i = 0, j = 0; s[j] != '\0'; i++, j++) {

    if (s[j] == '%') {

      uint8_t v;

      bool ok;

      ok = hex_byte(&s[j+1], &v);

      if (!ok) {

        return NULL;

      }

      j += 2; /* OK; hex_byte() has checked ahead */

      s[i] = (unsigned char)v;

    } else {

      s[i] = s[j];

    }

  }

  s[i] = '\0';

  return s + i;

}