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

 *                                  _   _ ____  _

 *  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"

struct Curl_easy;

#include "urldata.h"

#include "escape.h"

#include "curlx/strparse.h"

#include "curl_printf.h"

/* for ABI-compatibility with previous versions */

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

{

  return curl_easy_escape(NULL, string, length);

}

/* 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(CURL *curl, const char *string, int length)

{

  size_t len;

  struct dynbuf d;

  (void)curl;

  if(!string || (length < 0))

    return NULL;

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

  if(!len)

    return curlx_strdup("");

  if(len > SIZE_MAX / 16)

    return NULL;

  curlx_dyn_init(&d, (len * 3) + 1);

  while(len--) {

    /* treat the characters unsigned */

    unsigned char in = (unsigned char)*string++;

    if(ISUNRESERVED(in)) {

      /* append this */

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

        return NULL;

    }

    else {

      /* encode it */

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

      Curl_hexbyte(&out[1], in);

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

        return NULL;

    }

  }

  return curlx_dyn_ptr(&d);

}

/*

 * 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 = curlx_malloc(alloc + 1);

  if(!ns)

    return CURLE_OUT_OF_MEMORY;

  /* store output string */

  *ostring = ns;

  while(alloc) {

    unsigned char in = (unsigned char)*string;

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

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

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

      in = (unsigned char)((curlx_hexval(string[1]) << 4) |

                           curlx_hexval(string[2]));

      string += 3;

      alloc -= 3;

    }

    else {

      string++;

      alloc--;

    }

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

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

      curlx_safefree(*ostring);

      return CURLE_URL_MALFORMAT;

    }

    *ns++ = (char)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(CURL *curl, const char *string, int inlength,

                         int *outlength)

{

  char *str = NULL;

  (void)curl;

  if(string && (inlength >= 0)) {

    size_t inputlen = (size_t)inlength;

    size_t outputlen;

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

                                  REJECT_NADA);

    if(res)

      return NULL;

    if(outlength) {

      if(outputlen <= (size_t)INT_MAX)

        *outlength = curlx_uztosi(outputlen);

      else

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

        curlx_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)

{

  curlx_free(p);

}

/*

 * Curl_hexencode()

 *

 * Converts binary input to lowercase hex-encoded ASCII output.

 * Null-terminated.

 */

void Curl_hexencode(const unsigned char *src, size_t len, /* input length */

                    unsigned char *out, size_t olen) /* output buffer size */

{

  DEBUGASSERT(src && len && (olen >= 3));

  if(src && len && (olen >= 3)) {

    while(len-- && (olen >= 3)) {

      out[0] = Curl_ldigits[*src >> 4];

      out[1] = Curl_ldigits[*src & 0x0F];

      ++src;

      out += 2;

      olen -= 2;

    }

    *out = 0;

  }

  else if(olen)

    *out = 0;

}

/* Curl_hexbyte

 *

 * Output a single unsigned char as a two-digit UPPERCASE hex number.

 */

void Curl_hexbyte(unsigned char *dest, /* must fit two bytes */

                  unsigned char val)

{

  dest[0] = Curl_udigits[val >> 4];

  dest[1] = Curl_udigits[val & 0x0F];

}