#include <ctype.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>

int decode_uri(char *uri, char *resbuf)
{
  int i = 0, j = 0;
  char c, code[3] = {NULL, NULL, NULL};

  while ((c = uri[i++]) != NULL) {
    if (c == '%') 
      if (isxdigit(uri[i]) && (uri[i+1] != NULL) && isxdigit(uri[i+1])) {
	strncpy(code, &uri[i], 2); 
	resbuf[j++] = (char) strtol(code, NULL, 16);
	i += 2;
      } 
      else return -1;
    else 
      resbuf[j++] = c;
  }
  return 0;
}