escape.c

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 *  The contents of this file are subject to the Mozilla Public License
 *  Version 1.0 (the "License"); you may not use this file except in
 *  compliance with the License. You may obtain a copy of the License at
 *  http://www.mozilla.org/MPL/
 *
 *  Software distributed under the License is distributed on an "AS IS"
 *  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
 *  License for the specific language governing rights and limitations
 *  under the License.
 *
 *  The Original Code is Curl.
 *
 *  The Initial Developer of the Original Code is Daniel Stenberg.
 *
 *  Portions created by the Initial Developer are Copyright (C) 1998.
 *  All Rights Reserved.
 *
 * ------------------------------------------------------------
 * Main author:
 * - Daniel Stenberg <daniel@haxx.se>
 *
 * 	http://curl.haxx.se
 *
 * $Source$
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 * $Date$
 * $Author$
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 * $Locker$
 *
 * ------------------------------------------------------------
 ****************************************************************************/

/* Escape and unescape URL encoding in strings. The functions return a new
 * allocated string or NULL if an error occurred.  */

#include "setup.h"
#include <curl/curl.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* The last #include file should be: */
#ifdef MALLOCDEBUG
#include "memdebug.h"
#endif

char *curl_escape(char *string)
{
   int alloc=strlen(string)+1;
   char *ns = malloc(alloc);
   unsigned char in;
   int newlen = alloc;
   int index=0;

   while(*string) {
      in = *string;
      if(' ' == in)
	 ns[index++] = '+';
      else if(!(in >= 'a' && in <= 'z') &&
	      !(in >= 'A' && in <= 'Z') &&
	      !(in >= '0' && in <= '9')) {
	 /* encode it */
	 newlen += 2; /* the size grows with two, since this'll become a %XX */
	 if(newlen > alloc) {
	    alloc *= 2;
	    ns = realloc(ns, alloc);
	    if(!ns)
	       return NULL;
	 }
	 sprintf(&ns[index], "%%%02X", in);
	 index+=3;
      }
      else {
	 /* just copy this */
	 ns[index++]=in;
      }
      string++;
   }
   ns[index]=0; /* terminate it */
   return ns;
}

char *curl_unescape(char *string, int length)
{
   int alloc = (length?length:strlen(string))+1;
   char *ns = malloc(alloc);
   unsigned char in;
   int index=0;
   int hex;
   char querypart=FALSE; /* everything to the right of a '?' letter is
                            the "query part" where '+' should become ' '.
                            RFC 2316, section 3.10 */
  
   while(--alloc) {
      in = *string;
      if(querypart && ('+' == in))
         in = ' ';
      else if(!querypart && ('?' == in)) {
        /* we have "walked in" to the query part */
        querypart=TRUE;
      }
      else if('%' == in) {
        /* encoded part */
        if(sscanf(string+1, "%02X", &hex)) {
          in = hex;
          string+=2;
        }
      }

      ns[index++] = in;
      string++;
   }
   ns[index]=0; /* terminate it */
   return ns;
  
}