code: public static int consumeCRLF(final Buffer buffer) throws SipParseException {
          try {
              buffer.markReaderIndex();
              final byte cr = buffer.readByte();
              final byte lf = buffer.readByte();
              if (cr == CR && lf == LF) {
                  return 2;
              }
          } catch (final IndexOutOfBoundsException e) {
              // fall through
          } catch (final IOException e) {
              throw new SipParseException(buffer.getReaderIndex(), UNABLE_TO_READ_FROM_STREAM, e);
          }
          buffer.resetReaderIndex();
          return 0;
      }
docs: Consume CR + LF
  
  @param buffer
  @return the number of bytes we consumed, which should be two
  if we indeed consumed CRLF or zero otherwise.