dtls1_get_message_fragment(SSL *s, int st1, int stn, long max, int *ok)
	{
	unsigned char wire[DTLS1_HM_HEADER_LENGTH];
	unsigned long len, frag_off, frag_len;
	int i,al;
	struct hm_header_st msg_hdr;

	/* see if we have the required fragment already */
	if ((frag_len = dtls1_retrieve_buffered_fragment(s,max,ok)) || *ok)
		{
		if (*ok)	s->init_num = frag_len;
		return frag_len;
		}

	/* read handshake message header */
	i=s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,wire,
		DTLS1_HM_HEADER_LENGTH, 0);
	if (i <= 0) 	/* nbio, or an error */
		{
		s->rwstate=SSL_READING;
		*ok = 0;
		return i;
		}
	/* Handshake fails if message header is incomplete */
	if (i != DTLS1_HM_HEADER_LENGTH)
		{
		al=SSL_AD_UNEXPECTED_MESSAGE;
		SSLerr(SSL_F_DTLS1_GET_MESSAGE_FRAGMENT,SSL_R_UNEXPECTED_MESSAGE);
		goto f_err;
		}

	/* parse the message fragment header */
	dtls1_get_message_header(wire, &msg_hdr);

	/* 
	 * if this is a future (or stale) message it gets buffered
	 * (or dropped)--no further processing at this time
	 * While listening, we accept seq 1 (ClientHello with cookie)
	 * although we're still expecting seq 0 (ClientHello)
	 */
	if (msg_hdr.seq != s->d1->handshake_read_seq && !(s->d1->listen && msg_hdr.seq == 1))
		return dtls1_process_out_of_seq_message(s, &msg_hdr, ok);

	len = msg_hdr.msg_len;
	frag_off = msg_hdr.frag_off;
	frag_len = msg_hdr.frag_len;

	if (frag_len && frag_len < len)
		return dtls1_reassemble_fragment(s, &msg_hdr, ok);

	if (!s->server && s->d1->r_msg_hdr.frag_off == 0 &&
		wire[0] == SSL3_MT_HELLO_REQUEST)
		{
		/* The server may always send 'Hello Request' messages --
		 * we are doing a handshake anyway now, so ignore them
		 * if their format is correct. Does not count for
		 * 'Finished' MAC. */
		if (wire[1] == 0 && wire[2] == 0 && wire[3] == 0)
			{
			if (s->msg_callback)
				s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, 
					wire, DTLS1_HM_HEADER_LENGTH, s, 
					s->msg_callback_arg);
			
			s->init_num = 0;
			return dtls1_get_message_fragment(s, st1, stn,
				max, ok);
			}
		else /* Incorrectly formated Hello request */
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_DTLS1_GET_MESSAGE_FRAGMENT,SSL_R_UNEXPECTED_MESSAGE);
			goto f_err;
			}
		}

	if ((al=dtls1_preprocess_fragment(s,&msg_hdr,max)))
		goto f_err;

	/* XDTLS:  ressurect this when restart is in place */
	s->state=stn;

	if ( frag_len > 0)
		{
		unsigned char *p=(unsigned char *)s->init_buf->data+DTLS1_HM_HEADER_LENGTH;

		i=s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
			&p[frag_off],frag_len,0);
		/* XDTLS:  fix this--message fragments cannot span multiple packets */
		if (i <= 0)
			{
			s->rwstate=SSL_READING;
			*ok = 0;
			return i;
			}
		}
	else
		i = 0;

	/* XDTLS:  an incorrectly formatted fragment should cause the 
	 * handshake to fail */
	if (i != (int)frag_len)
		{
		al=SSL3_AD_ILLEGAL_PARAMETER;
		SSLerr(SSL_F_DTLS1_GET_MESSAGE_FRAGMENT,SSL3_AD_ILLEGAL_PARAMETER);
		goto f_err;
		}

	*ok = 1;

	/* Note that s->init_num is *not* used as current offset in
	 * s->init_buf->data, but as a counter summing up fragments'
	 * lengths: as soon as they sum up to handshake packet
	 * length, we assume we have got all the fragments. */
	s->init_num = frag_len;
	return frag_len;

f_err:
	ssl3_send_alert(s,SSL3_AL_FATAL,al);
	s->init_num = 0;

	*ok=0;
	return(-1);
	}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.