/***************************************************************************

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

 *                             / __| | | | |_) | |

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * are also available at https://curl.se/docs/copyright.html.

 *

 * You may opt to use, copy, modify, merge, publish, distribute and/or sell

 * copies of the Software, and permit persons to whom the Software is

 * furnished to do so, under the terms of the COPYING file.

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY

 * KIND, either express or implied.

 *

 * SPDX-License-Identifier: curl

 *

 ***************************************************************************/

/* Escape and unescape URL encoding in strings. The functions return a new

 * allocated string or NULL if an error occurred.  */

#include "curl_setup.h"

#include <curl/curl.h>

#include "urldata.h"

#include "warnless.h"

#include "escape.h"

#include "strdup.h"

/* The last 3 #include files should be in this order */

#include "curl_printf.h"

#include "curl_memory.h"

#include "memdebug.h"

/* Portable character check (remember EBCDIC). Do not use isalnum() because

   its behavior is altered by the current locale.

   See https://datatracker.ietf.org/doc/html/rfc3986#section-2.3

*/

bool Curl_isunreserved(unsigned char in)

{

  switch(in) {

    case '0': case '1': case '2': case '3': case '4':

    case '5': case '6': case '7': case '8': case '9':

    case 'a': case 'b': case 'c': case 'd': case 'e':

    case 'f': case 'g': case 'h': case 'i': case 'j':

    case 'k': case 'l': case 'm': case 'n': case 'o':

    case 'p': case 'q': case 'r': case 's': case 't':

    case 'u': case 'v': case 'w': case 'x': case 'y': case 'z':

    case 'A': case 'B': case 'C': case 'D': case 'E':

    case 'F': case 'G': case 'H': case 'I': case 'J':

    case 'K': case 'L': case 'M': case 'N': case 'O':

    case 'P': case 'Q': case 'R': case 'S': case 'T':

    case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':

    case '-': case '.': case '_': case '~':

      return TRUE;

    default:

      break;

  }

  return FALSE;

}

/* for ABI-compatibility with previous versions */

char *curl_escape(const char *string, int inlength)

{

  return curl_easy_escape(NULL, string, inlength);

}

/* for ABI-compatibility with previous versions */

char *curl_unescape(const char *string, int length)

{

  return curl_easy_unescape(NULL, string, length, NULL);

}

/* Escapes for URL the given unescaped string of given length.

 * 'data' is ignored since 7.82.0.

 */

char *curl_easy_escape(struct Curl_easy *data, const char *string,

                       int inlength)

{

  size_t length;

  struct dynbuf d;

  (void)data;

  if(inlength < 0)

    return NULL;

  Curl_dyn_init(&d, CURL_MAX_INPUT_LENGTH * 3);

  length = (inlength?(size_t)inlength:strlen(string));

  if(!length)

    return strdup("");

  while(length--) {

    unsigned char in = *string++; /* treat the characters unsigned */

    if(Curl_isunreserved(in)) {

      /* append this */

      if(Curl_dyn_addn(&d, &in, 1))

        return NULL;

    }

    else {

      /* encode it */

      const char hex[] = "0123456789ABCDEF";

      char out[3]={'%'};

      out[1] = hex[in>>4];

      out[2] = hex[in & 0xf];

      if(Curl_dyn_addn(&d, out, 3))

        return NULL;

    }

  }

  return Curl_dyn_ptr(&d);

}

static const unsigned char hextable[] = {

  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0,       /* 0x30 - 0x3f */

  0, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x40 - 0x4f */

  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,       /* 0x50 - 0x5f */

  0, 10, 11, 12, 13, 14, 15                             /* 0x60 - 0x66 */

};

/* the input is a single hex digit */

#define onehex2dec(x) hextable[x - '0']

/*

 * Curl_urldecode() URL decodes the given string.

 *

 * Returns a pointer to a malloced string in *ostring with length given in

 * *olen. If length == 0, the length is assumed to be strlen(string).

 *

 * ctrl options:

 * - REJECT_NADA: accept everything

 * - REJECT_CTRL: rejects control characters (byte codes lower than 32) in

 *                the data

 * - REJECT_ZERO: rejects decoded zero bytes

 *

 * The values for the enum starts at 2, to make the assert detect legacy

 * invokes that used TRUE/FALSE (0 and 1).

 */

CURLcode Curl_urldecode(const char *string, size_t length,

                        char **ostring, size_t *olen,

                        enum urlreject ctrl)

{

  size_t alloc;

  char *ns;

  DEBUGASSERT(string);

  DEBUGASSERT(ctrl >= REJECT_NADA); /* crash on TRUE/FALSE */

  alloc = (length?length:strlen(string));

  ns = malloc(alloc + 1);

  if(!ns)

    return CURLE_OUT_OF_MEMORY;

  /* store output string */

  *ostring = ns;

  while(alloc) {

    unsigned char in = *string;

    if(('%' == in) && (alloc > 2) &&

       ISXDIGIT(string[1]) && ISXDIGIT(string[2])) {

      /* this is two hexadecimal digits following a '%' */

      in = (unsigned char)(onehex2dec(string[1]) << 4) | onehex2dec(string[2]);

      string += 3;

      alloc -= 3;

    }

    else {

      string++;

      alloc--;

    }

    if(((ctrl == REJECT_CTRL) && (in < 0x20)) ||

       ((ctrl == REJECT_ZERO) && (in == 0))) {

      Curl_safefree(*ostring);

      return CURLE_URL_MALFORMAT;

    }

    *ns++ = in;

  }

  *ns = 0; /* terminate it */

  if(olen)

    /* store output size */

    *olen = ns - *ostring;

  return CURLE_OK;

}

/*

 * Unescapes the given URL escaped string of given length. Returns a

 * pointer to a malloced string with length given in *olen.

 * If length == 0, the length is assumed to be strlen(string).

 * If olen == NULL, no output length is stored.

 * 'data' is ignored since 7.82.0.

 */

char *curl_easy_unescape(struct Curl_easy *data, const char *string,

                         int length, int *olen)

{

  char *str = NULL;

  (void)data;

  if(length >= 0) {

    size_t inputlen = (size_t)length;

    size_t outputlen;

    CURLcode res = Curl_urldecode(string, inputlen, &str, &outputlen,

                                  REJECT_NADA);

    if(res)

      return NULL;

    if(olen) {

      if(outputlen <= (size_t) INT_MAX)

        *olen = curlx_uztosi(outputlen);

      else

        /* too large to return in an int, fail! */

        Curl_safefree(str);

    }

  }

  return str;

}

/* For operating systems/environments that use different malloc/free

   systems for the app and for this library, we provide a free that uses

   the library's memory system */

void curl_free(void *p)

{

  free(p);

}