int do_dtls1_write(SSL *s, int type, const unsigned char *buf, unsigned int len, int create_empty_fragment)
	{
	unsigned char *p,*pseq;
	int i,mac_size,clear=0;
	int prefix_len = 0;
	SSL3_RECORD *wr;
	SSL3_BUFFER *wb;
	SSL_SESSION *sess;
	int bs;

	/* first check if there is a SSL3_BUFFER still being written
	 * out.  This will happen with non blocking IO */
	if (s->s3->wbuf.left != 0)
		{
		OPENSSL_assert(0); /* XDTLS:  want to see if we ever get here */
		return(ssl3_write_pending(s,type,buf,len));
		}

	/* If we have an alert to send, lets send it */
	if (s->s3->alert_dispatch)
		{
		i=s->method->ssl_dispatch_alert(s);
		if (i <= 0)
			return(i);
		/* if it went, fall through and send more stuff */
		}

	if (len == 0 && !create_empty_fragment)
		return 0;

	wr= &(s->s3->wrec);
	wb= &(s->s3->wbuf);
	sess=s->session;

	if (	(sess == NULL) ||
		(s->enc_write_ctx == NULL) ||
		(EVP_MD_CTX_md(s->write_hash) == NULL))
		clear=1;

	if (clear)
		mac_size=0;
	else
		mac_size=EVP_MD_CTX_size(s->write_hash);

	/* DTLS implements explicit IV, so no need for empty fragments */
#if 0
	/* 'create_empty_fragment' is true only when this function calls itself */
	if (!clear && !create_empty_fragment && !s->s3->empty_fragment_done
		&& SSL_version(s) != DTLS1_VERSION)
		{
		/* countermeasure against known-IV weakness in CBC ciphersuites
		 * (see http://www.openssl.org/~bodo/tls-cbc.txt) 
		 */

		if (s->s3->need_empty_fragments && type == SSL3_RT_APPLICATION_DATA)
			{
			/* recursive function call with 'create_empty_fragment' set;
			 * this prepares and buffers the data for an empty fragment
			 * (these 'prefix_len' bytes are sent out later
			 * together with the actual payload) */
			prefix_len = s->method->do_ssl_write(s, type, buf, 0, 1);
			if (prefix_len <= 0)
				goto err;

			if (s->s3->wbuf.len < (size_t)prefix_len + SSL3_RT_MAX_PACKET_SIZE)
				{
				/* insufficient space */
				SSLerr(SSL_F_DO_DTLS1_WRITE, ERR_R_INTERNAL_ERROR);
				goto err;
				}
			}
		
		s->s3->empty_fragment_done = 1;
		}
#endif

	p = wb->buf + prefix_len;

	/* write the header */

	*(p++)=type&0xff;
	wr->type=type;

	*(p++)=(s->version>>8);
	*(p++)=s->version&0xff;

	/* field where we are to write out packet epoch, seq num and len */
	pseq=p; 
	p+=10;

	/* lets setup the record stuff. */

	/* Make space for the explicit IV in case of CBC.
	 * (this is a bit of a boundary violation, but what the heck).
	 */
	if ( s->enc_write_ctx && 
		(EVP_CIPHER_mode( s->enc_write_ctx->cipher ) & EVP_CIPH_CBC_MODE))
		bs = EVP_CIPHER_block_size(s->enc_write_ctx->cipher);
	else
		bs = 0;

	wr->data=p + bs;  /* make room for IV in case of CBC */
	wr->length=(int)len;
	wr->input=(unsigned char *)buf;

	/* we now 'read' from wr->input, wr->length bytes into
	 * wr->data */

	/* first we compress */
	if (s->compress != NULL)
		{
		if (!ssl3_do_compress(s))
			{
			SSLerr(SSL_F_DO_DTLS1_WRITE,SSL_R_COMPRESSION_FAILURE);
			goto err;
			}
		}
	else
		{
		memcpy(wr->data,wr->input,wr->length);
		wr->input=wr->data;
		}

	/* we should still have the output to wr->data and the input
	 * from wr->input.  Length should be wr->length.
	 * wr->data still points in the wb->buf */

	if (mac_size != 0)
		{
		s->method->ssl3_enc->mac(s,&(p[wr->length + bs]),1);
		wr->length+=mac_size;
		}

	/* this is true regardless of mac size */
	wr->input=p;
	wr->data=p;


	/* ssl3_enc can only have an error on read */
	wr->length += bs;  /* bs != 0 in case of CBC.  The enc fn provides
						* the randomness */ 
	s->method->ssl3_enc->enc(s,1);

	/* record length after mac and block padding */
/*	if (type == SSL3_RT_APPLICATION_DATA ||
	(type == SSL3_RT_ALERT && ! SSL_in_init(s))) */
	
	/* there's only one epoch between handshake and app data */
	
	s2n(s->d1->w_epoch, pseq);

	/* XDTLS: ?? */
/*	else
	s2n(s->d1->handshake_epoch, pseq); */

	memcpy(pseq, &(s->s3->write_sequence[2]), 6);
	pseq+=6;
	s2n(wr->length,pseq);

	/* we should now have
	 * wr->data pointing to the encrypted data, which is
	 * wr->length long */
	wr->type=type; /* not needed but helps for debugging */
	wr->length+=DTLS1_RT_HEADER_LENGTH;

#if 0  /* this is now done at the message layer */
	/* buffer the record, making it easy to handle retransmits */
	if ( type == SSL3_RT_HANDSHAKE || type == SSL3_RT_CHANGE_CIPHER_SPEC)
		dtls1_buffer_record(s, wr->data, wr->length, 
			*((PQ_64BIT *)&(s->s3->write_sequence[0])));
#endif

	ssl3_record_sequence_update(&(s->s3->write_sequence[0]));

	if (create_empty_fragment)
		{
		/* we are in a recursive call;
		 * just return the length, don't write out anything here
		 */
		return wr->length;
		}

	/* now let's set up wb */
	wb->left = prefix_len + wr->length;
	wb->offset = 0;

	/* memorize arguments so that ssl3_write_pending can detect bad write retries later */
	s->s3->wpend_tot=len;
	s->s3->wpend_buf=buf;
	s->s3->wpend_type=type;
	s->s3->wpend_ret=len;

	/* we now just need to write the buffer */
	return ssl3_write_pending(s,type,buf,len);
err:
	return -1;
	}