/*
*
*  This software was developed by the Thermal Modeling and Analysis
*  Project(TMAP) of the National Oceanographic and Atmospheric
*  Administration's (NOAA) Pacific Marine Environmental Lab(PMEL),
*  hereafter referred to as NOAA/PMEL/TMAP.
*
*  Access and use of this software shall impose the following
*  obligations and understandings on the user. The user is granted the
*  right, without any fee or cost, to use, copy, modify, alter, enhance
*  and distribute this software, and any derivative works thereof, and
*  its supporting documentation for any purpose whatsoever, provided
*  that this entire notice appears in all copies of the software,
*  derivative works and supporting documentation.  Further, the user
*  agrees to credit NOAA/PMEL/TMAP in any publications that result from
*  the use of this software or in any product that includes this
*  software. The names TMAP, NOAA and/or PMEL, however, may not be used
*  in any advertising or publicity to endorse or promote any products
*  or commercial entity unless specific written permission is obtained
*  from NOAA/PMEL/TMAP. The user also understands that NOAA/PMEL/TMAP
*  is not obligated to provide the user with any support, consulting,
*  training or assistance of any kind with regard to the use, operation
*  and performance of this software nor to provide the user with any
*  updates, revisions, new versions or "bug fixes".
*
*  THIS SOFTWARE IS PROVIDED BY NOAA/PMEL/TMAP "AS IS" AND ANY EXPRESS
*  OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
*  ARE DISCLAIMED. IN NO EVENT SHALL NOAA/PMEL/TMAP BE LIABLE FOR ANY SPECIAL,
*  INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
*  RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
*  CONTRACT, NEGLIGENCE OR OTHER TORTUOUS ACTION, ARISING OUT OF OR IN
*  CONNECTION WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.  
*
*/

#include <string.h>

/* Code from http://geekhideout.com/urlcode.shtml
Comments:

URL Encoding/Decoding in C
Recently I had the need to encode and decode URL-encoded strings. After doing a 
brief search of what was available, I found that most of the code I was seeing 
wasn't terribly efficient and/or was rather poorly written. I decided to whip 
up my own routines and am sharing them here.

Public Domain

To the extent possible under law, Fred Bulback has waived all copyright and 
related or neighboring rights to URL Encoding/Decoding in C. This work is 
published from: United States.

ACM 2/2013: v6.85 For addition of LET/REMOTE qualifier. 
url_encode was edited to send input string and output string as 
arguments and to return the length of the encoded string.
*/

/* Converts a hex character to its integer value */
char from_hex(char ch) {
  return isdigit(ch) ? ch - '0' : tolower(ch) - 'a' + 10;
}

/* Converts an integer value to its hex character*/
char to_hex(char code) {
  static char hex[] = "0123456789abcdef";
  return hex[code & 15];
}

/* Returns a url-encoded version of str */
/* IMPORTANT: be sure to free() the returned string after use */
void *url_encode_(char *str, char *outstr, int *outlen) {
  char *pstr = str, *pbuf = outstr;
  while (*pstr) {
    if (isalnum(*pstr) || *pstr == '-' || *pstr == '_' || *pstr == '.' || *pstr == '~') 
      *pbuf++ = *pstr;
    else if (*pstr == ' ') 
      *pbuf++ = '+';
    else 
      *pbuf++ = '%', *pbuf++ = to_hex(*pstr >> 4), *pbuf++ = to_hex(*pstr & 15);
    pstr++;
  }
  *outlen = strlen(outstr);
  *pbuf = '\0';
  return 0;
}

/* Returns a url-decoded version of str */
/* IMPORTANT: be sure to free() the returned string after use */
int *url_decode(char *str, char *outstr) {
  char *pstr = str, *pbuf = outstr;
  while (*pstr) {
    if (*pstr == '%') {
      if (pstr[1] && pstr[2]) {
        *pbuf++ = from_hex(pstr[1]) << 4 | from_hex(pstr[2]);
        pstr += 2;
      }
    } else if (*pstr == '+') { 
      *pbuf++ = ' ';
    } else {
      *pbuf++ = *pstr;
    }
    pstr++;
  }
  *pbuf = '\0';
  return 0;
}

