text: /***************************************************************************
   *                                  _   _ ____  _
   *  Project                     ___| | | |  _ \| |
   *                             / __| | | | |_) | |
   *                            | (__| |_| |  _ <| |___
   *                             \___|\___/|_| \_\_____|
   *
   * Copyright (C) 1998 - 2017, 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.haxx.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.
   *
   ***************************************************************************/
  
  /* 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 "non-ascii.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://tools.ietf.org/html/rfc3986#section-2.3
  */
  static 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);
  }
  
  char *curl_easy_escape(struct Curl_easy *data, const char *string,
                         int inlength)
  {
    size_t alloc;
    char *ns;
    char *testing_ptr = NULL;
    unsigned char in; /* we need to treat the characters unsigned */
    size_t newlen;
    size_t strindex = 0;
    size_t length;
    CURLcode result;
  
    if(inlength < 0)
      return NULL;
  
    alloc = (inlength?(size_t)inlength:strlen(string)) + 1;
    newlen = alloc;
  
    ns = malloc(alloc);
    if(!ns)
      return NULL;
  
    length = alloc-1;
    while(length--) {
      in = *string;
  
      if(Curl_isunreserved(in))
        /* just copy this */
        ns[strindex++] = in;
      else {
        /* encode it */
        newlen += 2; /* the size grows with two, since this'll become a %XX */
        if(newlen > alloc) {
          alloc *= 2;
          testing_ptr = Curl_saferealloc(ns, alloc);
          if(!testing_ptr)
            return NULL;
          ns = testing_ptr;
        }
  
        result = Curl_convert_to_network(data, (char *)&in, 1);
        if(result) {
          /* Curl_convert_to_network calls failf if unsuccessful */
          free(ns);
          return NULL;
        }
  
        snprintf(&ns[strindex], 4, "%%%02X", in);
  
        strindex += 3;
      }
      string++;
    }
    ns[strindex] = 0; /* terminate it */
    return ns;
  }
  
  /*
   * Curl_urldecode() URL decodes the given string.
   *
   * Optionally detects control characters (byte codes lower than 32) in the
   * data and rejects such data.
   *
   * 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).
   *
   */
  CURLcode Curl_urldecode(struct Curl_easy *data,
                          const char *string, size_t length,
                          char **ostring, size_t *olen,
                          bool reject_ctrl)
  {
    size_t alloc = (length?length:strlen(string)) + 1;
    char *ns = malloc(alloc);
    unsigned char in;
    size_t strindex = 0;
    unsigned long hex;
    CURLcode result;
  
    if(!ns)
      return CURLE_OUT_OF_MEMORY;
  
    while(--alloc > 0) {
      in = *string;
      if(('%' == in) && (alloc > 2) &&
         ISXDIGIT(string[1]) && ISXDIGIT(string[2])) {
        /* this is two hexadecimal digits following a '%' */
        char hexstr[3];
        char *ptr;
        hexstr[0] = string[1];
        hexstr[1] = string[2];
        hexstr[2] = 0;
  
        hex = strtoul(hexstr, &ptr, 16);
  
        in = curlx_ultouc(hex); /* this long is never bigger than 255 anyway */
  
        result = Curl_convert_from_network(data, (char *)&in, 1);
        if(result) {
          /* Curl_convert_from_network calls failf if unsuccessful */
          free(ns);
          return result;
        }
  
        string += 2;
        alloc -= 2;
      }
  
      if(reject_ctrl && (in < 0x20)) {
        free(ns);
        return CURLE_URL_MALFORMAT;
      }
  
      ns[strindex++] = in;
      string++;
    }
    ns[strindex] = 0; /* terminate it */
  
    if(olen)
      /* store output size */
      *olen = strindex;
  
    /* store output string */
    *ostring = ns;
  
    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.
   */
  char *curl_easy_unescape(struct Curl_easy *data, const char *string,
                           int length, int *olen)
  {
    char *str = NULL;
    if(length >= 0) {
      size_t inputlen = length;
      size_t outputlen;
      CURLcode res = Curl_urldecode(data, string, inputlen, &str, &outputlen,
                                    FALSE);
      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);
  }
  