string UriEscape(const string& input)
{
  int i = 0;
  string ret;
  char buffer [16]; //TODO: Should this buffer be 16? 
                    // I only one character into hex at a time, so it should 
                    // never go over 4 chars (percent sign, two hex characters and the null).
  unsigned char c;
 
  for (i = 0; (c = input[i]) != '\0'; i++) { 
    if ((c == 0x2D) || (c == 0x2E) || // Hyphen-Minus, Full Stop
        ((0x30 <= c) && (c <= 0x39)) || // Digits [0-9]
        ((0x41 <= c) && (c <= 0x5A)) || // Uppercase [A-Z]
        ((0x61 <= c) && (c <= 0x7A))) { // Lowercase [a-z]
        ret += c;
    } else {
      sprintf (buffer, "%%%0.2X", c);
      ret += buffer;
    }
  }
  return ret;
}