import java.io.*;  // for InputStream and ByteArrayOutputStream

public class Framer {

  public static byte[] nextToken(InputStream in, byte[] delimiter)
      throws IOException {
    int nextByte;

    // If the stream has already ended, return null
    if ((nextByte = in.read()) == -1)
      return null;

    ByteArrayOutputStream tokenBuffer = new ByteArrayOutputStream();
    do {
      tokenBuffer.write(nextByte);
      byte[] currentToken = tokenBuffer.toByteArray();
      if (endsWith(currentToken, delimiter)) {
        int tokenLength = currentToken.length - delimiter.length;
        byte[] token = new byte[tokenLength];
        System.arraycopy(currentToken, 0, token, 0, tokenLength); 
        return token;
      }
    } while ((nextByte = in.read()) != -1);   // Stop on EOS
    return tokenBuffer.toByteArray();         // Received at least one byte
  }

  // Returns true if value ends with the bytes in suffix
  private static boolean endsWith(byte[] value, byte[] suffix) {
    if (value.length < suffix.length)
      return false;
    
     for (int offset = 1; offset <= suffix.length; offset++)
       if (value[value.length - offset] != suffix[suffix.length - offset])
         return false;
     return true;
  }
}