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

 *                                  _   _ ____  _

 *  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);

}

#define NOPE 0xff

#define _OK_ 0x1f /* octet not needing encoding but not a hexadecimal

                     character */

static const unsigned char hextable[256] = {

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, /* 00 */

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, /* 08 */

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, /* 10 */

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, /* 18 */

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, /* 20 */

  NOPE, NOPE, NOPE, NOPE, NOPE, _OK_, _OK_, NOPE, /* 28 */

  0,    1,    2,    3,    4,    5,    6,    7,    /* 30 */

  8,    9,    NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, /* 38 */

  NOPE, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, _OK_, /* 40 */

  _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, /* 48 */

  _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, /* 50 */

  _OK_, _OK_, _OK_, NOPE, NOPE, NOPE, NOPE, _OK_, /* 58 */

  NOPE, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, _OK_, /* 60 */

  _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, /* 68 */

  _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, _OK_, /* 70 */

  _OK_, _OK_, _OK_, NOPE, NOPE, NOPE, _OK_, NOPE, /* 78 */

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, /* 80 - not ASCII */

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE,

  NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE, NOPE

};

/* 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;

  const char *f = string;

  size_t nappend = 0;

  char *target;

  char *encoded;

  (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;

  encoded = target = curlx_malloc((len * 3) + 1);

  if(!target)

    return NULL;

  while(len--) {

    uint8_t in = (uint8_t)*string++;

    if(!(hextable[in] & 0x80))

      /* append this */

      nappend++;

    else {

      if(nappend) {

        memcpy(target, f, nappend);

        target += nappend;

        nappend = 0;

      }

      f = string;

      /* encode it */

      target[0] = '%';

      target[1] = Curl_udigits[in >> 4];

      target[2] = Curl_udigits[in & 0x0F];

      target += 3;

    }

  }

  if(nappend) {

    memcpy(target, f, nappend);

    target += nappend;

  }

  *target = '\0'; /* null terminate */

  return encoded;

}

/*

 * 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;

  uint8_t reject_limit;

  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;

  reject_limit = (ctrl == REJECT_CTRL) ? 0x20 :

    (ctrl == REJECT_ZERO) ? 1 : 0;

  while(alloc) {

    uint8_t in;

    if(*string == '%') {

      if(alloc > 2) {

        uint8_t h1 = hextable[(uint8_t)string[1]];

        uint8_t h2 = hextable[(uint8_t)string[2]];

        if(!((h1 | h2) & 0xf0)) {

          in = (uint8_t)((h1 << 4) | h2);

          string += 3;

          alloc -= 3;

          if(in < reject_limit)

            goto error;

          *ns++ = (char)in;

          continue;

        }

      }

      in = '%';

      string++;

      alloc--;

      *ns++ = (char)in;

      continue;

    }

    else {

      const char *p = memchr(string + 1, '%', alloc - 1);

      size_t n = p ? (size_t)(p - string) : alloc;

      if(reject_limit) {

        if(reject_limit == 1) {

          if(memchr(string, 0, n))

            goto error;

        }

        else {

          size_t i;

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

            if((uint8_t)string[i] < 0x20)

              goto error;

          }

        }

      }

      memcpy(ns, string, n);

      ns += n;

      string += n;

      alloc -= n;

    }

  }

  *ns = 0; /* terminate it */

  if(olen)

    /* store output size */

    *olen = (size_t)(ns - *ostring);

  return CURLE_OK;

error:

  curlx_safefree(*ostring);

  return CURLE_URL_MALFORMAT;

}

/*

 * 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];

}