escape.c

/*****************************************************************************
 *                                  _   _ ____  _     
 *  Project                     ___| | | |  _ \| |    
 *                             / __| | | | |_) | |    
 *                            | (__| |_| |  _ <| |___ 
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 2000, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * In order to be useful for every potential user, curl and libcurl are
 * dual-licensed under the MPL and the MIT/X-derivate licenses.
 *
 * 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 MPL or the MIT/X-derivate
 * licenses. You may pick one of these licenses.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id$
 *****************************************************************************/

/* 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 > 0) {
      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;
          alloc-=2;
        }
      }

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