d1_pkt.c

/* ssl/d1_pkt.c */
/* 
 * DTLS implementation written by Nagendra Modadugu
 * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.  
 */
/* ====================================================================
 * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <stdio.h>
#include <errno.h>
#define USE_SOCKETS
#include "ssl_locl.h"
#include <openssl/evp.h>
#include <openssl/buffer.h>
#include <openssl/pqueue.h>
#include <openssl/rand.h>

/* mod 128 saturating subtract of two 64-bit values in big-endian order */
static int satsub64be(const unsigned char *v1,const unsigned char *v2)
{	int ret,sat,brw,i;

	if (sizeof(long) == 8) do
	{	const union { long one; char little; } is_endian = {1};
		long l;

		if (is_endian.little)			break;
		/* not reached on little-endians */
		/* following test is redundant, because input is
		 * always aligned, but I take no chances... */
		if (((size_t)v1|(size_t)v2)&0x7)	break;

		l  = *((long *)v1);
		l -= *((long *)v2);
		if (l>128)		return 128;
		else if (l<-128)	return -128;
		else			return (int)l;
	} while (0);

	ret = (int)v1[7]-(int)v2[7];
	sat = 0;
	brw = ret>>8;	/* brw is either 0 or -1 */
	if (ret & 0x80)
	{	for (i=6;i>=0;i--)
		{	brw += (int)v1[i]-(int)v2[i];
			sat |= ~brw;
			brw >>= 8;
		}
	}
	else
	{	for (i=6;i>=0;i--)
		{	brw += (int)v1[i]-(int)v2[i];
			sat |= brw;
			brw >>= 8;
		}
	}
	brw <<= 8;	/* brw is either 0 or -256 */

	if (sat&0xff)	return brw | 0x80;
	else		return brw + (ret&0xFF);
}

static int have_handshake_fragment(SSL *s, int type, unsigned char *buf, 
	int len, int peek);
static int dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap);
static void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap);
static DTLS1_BITMAP *dtls1_get_bitmap(SSL *s, SSL3_RECORD *rr, 
    unsigned int *is_next_epoch);
#if 0
static int dtls1_record_needs_buffering(SSL *s, SSL3_RECORD *rr,
	unsigned short *priority, unsigned long *offset);
#endif
static int dtls1_buffer_record(SSL *s, record_pqueue *q,
	unsigned char *priority);
static int dtls1_process_record(SSL *s);

/* copy buffered record into SSL structure */
static int
dtls1_copy_record(SSL *s, pitem *item)
    {
    DTLS1_RECORD_DATA *rdata;

    rdata = (DTLS1_RECORD_DATA *)item->data;
    
    if (s->s3->rbuf.buf != NULL)
        OPENSSL_free(s->s3->rbuf.buf);
    
    s->packet = rdata->packet;
    s->packet_length = rdata->packet_length;
    memcpy(&(s->s3->rbuf), &(rdata->rbuf), sizeof(SSL3_BUFFER));
    memcpy(&(s->s3->rrec), &(rdata->rrec), sizeof(SSL3_RECORD));
	
	/* Set proper sequence number for mac calculation */
	memcpy(&(s->s3->read_sequence[2]), &(rdata->packet[5]), 6);
    
    return(1);
    }


static int
dtls1_buffer_record(SSL *s, record_pqueue *queue, unsigned char *priority)
	{
	DTLS1_RECORD_DATA *rdata;
	pitem *item;

	/* Limit the size of the queue to prevent DOS attacks */
	if (pqueue_size(queue->q) >= 100)
		return 0;
		
	rdata = OPENSSL_malloc(sizeof(DTLS1_RECORD_DATA));
	item = pitem_new(priority, rdata);
	if (rdata == NULL || item == NULL)
		{
		if (rdata != NULL) OPENSSL_free(rdata);
		if (item != NULL) pitem_free(item);
		
		SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
		return(0);
		}
	
	rdata->packet = s->packet;
	rdata->packet_length = s->packet_length;
	memcpy(&(rdata->rbuf), &(s->s3->rbuf), sizeof(SSL3_BUFFER));
	memcpy(&(rdata->rrec), &(s->s3->rrec), sizeof(SSL3_RECORD));

	item->data = rdata;

#ifndef OPENSSL_NO_SCTP
	/* Store bio_dgram_sctp_rcvinfo struct */
	if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
	    (s->state == SSL3_ST_SR_FINISHED_A || s->state == SSL3_ST_CR_FINISHED_A)) {
		BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SCTP_GET_RCVINFO, sizeof(rdata->recordinfo), &rdata->recordinfo);
	}
#endif

	s->packet = NULL;
	s->packet_length = 0;
	memset(&(s->s3->rbuf), 0, sizeof(SSL3_BUFFER));
	memset(&(s->s3->rrec), 0, sizeof(SSL3_RECORD));
	
	if (!ssl3_setup_buffers(s))
		{
		SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
		OPENSSL_free(rdata);
		pitem_free(item);
		return(0);
		}

	/* insert should not fail, since duplicates are dropped */
	if (pqueue_insert(queue->q, item) == NULL)
		{
		SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
		OPENSSL_free(rdata);
		pitem_free(item);
		return(0);
		}

	return(1);
	}


static int
dtls1_retrieve_buffered_record(SSL *s, record_pqueue *queue)
    {
    pitem *item;

    item = pqueue_pop(queue->q);
    if (item)
        {
        dtls1_copy_record(s, item);

        OPENSSL_free(item->data);
		pitem_free(item);

        return(1);
        }

    return(0);
    }


/* retrieve a buffered record that belongs to the new epoch, i.e., not processed 
 * yet */
#define dtls1_get_unprocessed_record(s) \
                   dtls1_retrieve_buffered_record((s), \
                   &((s)->d1->unprocessed_rcds))

/* retrieve a buffered record that belongs to the current epoch, ie, processed */
#define dtls1_get_processed_record(s) \
                   dtls1_retrieve_buffered_record((s), \
                   &((s)->d1->processed_rcds))

static int
dtls1_process_buffered_records(SSL *s)
    {
    pitem *item;
    
    item = pqueue_peek(s->d1->unprocessed_rcds.q);
    if (item)
        {
        /* Check if epoch is current. */
        if (s->d1->unprocessed_rcds.epoch != s->d1->r_epoch)
            return(1);  /* Nothing to do. */
        
        /* Process all the records. */
        while (pqueue_peek(s->d1->unprocessed_rcds.q))
            {
            dtls1_get_unprocessed_record(s);
            if ( ! dtls1_process_record(s))
                return(0);
            dtls1_buffer_record(s, &(s->d1->processed_rcds), 
                s->s3->rrec.seq_num);
            }
        }

    /* sync epoch numbers once all the unprocessed records 
     * have been processed */
    s->d1->processed_rcds.epoch = s->d1->r_epoch;
    s->d1->unprocessed_rcds.epoch = s->d1->r_epoch + 1;

    return(1);
    }


#if 0

static int
dtls1_get_buffered_record(SSL *s)
	{
	pitem *item;
	PQ_64BIT priority = 
		(((PQ_64BIT)s->d1->handshake_read_seq) << 32) | 
		((PQ_64BIT)s->d1->r_msg_hdr.frag_off);
	
	if ( ! SSL_in_init(s))  /* if we're not (re)negotiating, 
							   nothing buffered */
		return 0;


	item = pqueue_peek(s->d1->rcvd_records);
	if (item && item->priority == priority)
		{
		/* Check if we've received the record of interest.  It must be
		 * a handshake record, since data records as passed up without
		 * buffering */
		DTLS1_RECORD_DATA *rdata;
		item = pqueue_pop(s->d1->rcvd_records);
		rdata = (DTLS1_RECORD_DATA *)item->data;
		
		if (s->s3->rbuf.buf != NULL)
			OPENSSL_free(s->s3->rbuf.buf);
		
		s->packet = rdata->packet;
		s->packet_length = rdata->packet_length;
		memcpy(&(s->s3->rbuf), &(rdata->rbuf), sizeof(SSL3_BUFFER));
		memcpy(&(s->s3->rrec), &(rdata->rrec), sizeof(SSL3_RECORD));
		
		OPENSSL_free(item->data);
		pitem_free(item);
		
		/* s->d1->next_expected_seq_num++; */
		return(1);
		}
	
	return 0;
	}

#endif

static int
dtls1_process_record(SSL *s)
{
	int i,al;
	int enc_err;
	SSL_SESSION *sess;
	SSL3_RECORD *rr;
	unsigned int mac_size, orig_len;
	unsigned char md[EVP_MAX_MD_SIZE];

	rr= &(s->s3->rrec);
	sess = s->session;

	/* At this point, s->packet_length == SSL3_RT_HEADER_LNGTH + rr->length,
	 * and we have that many bytes in s->packet
	 */
	rr->input= &(s->packet[DTLS1_RT_HEADER_LENGTH]);

	/* ok, we can now read from 's->packet' data into 'rr'
	 * rr->input points at rr->length bytes, which
	 * need to be copied into rr->data by either
	 * the decryption or by the decompression
	 * When the data is 'copied' into the rr->data buffer,
	 * rr->input will be pointed at the new buffer */ 

	/* We now have - encrypted [ MAC [ compressed [ plain ] ] ]
	 * rr->length bytes of encrypted compressed stuff. */

	/* check is not needed I believe */
	if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH)
		{
		al=SSL_AD_RECORD_OVERFLOW;
		SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
		goto f_err;
		}

	/* decrypt in place in 'rr->input' */
	rr->data=rr->input;

	enc_err = s->method->ssl3_enc->enc(s,0);
	/* enc_err is:
	 *    0: (in non-constant time) if the record is publically invalid.
	 *    1: if the padding is valid
	 *    -1: if the padding is invalid */
	if (enc_err == 0)
		{
		/* For DTLS we simply ignore bad packets. */
		rr->length = 0;
		s->packet_length = 0;
		goto err;
		}

#ifdef TLS_DEBUG
printf("dec %d\n",rr->length);
{ unsigned int z; for (z=0; z<rr->length; z++) printf("%02X%c",rr->data[z],((z+1)%16)?' ':'\n'); }
printf("\n");
#endif

	/* r->length is now the compressed data plus mac */
	if ((sess != NULL) &&
	    (s->enc_read_ctx != NULL) &&
	    (EVP_MD_CTX_md(s->read_hash) != NULL))
		{
		/* s->read_hash != NULL => mac_size != -1 */
		unsigned char *mac = NULL;
		unsigned char mac_tmp[EVP_MAX_MD_SIZE];
		mac_size=EVP_MD_CTX_size(s->read_hash);
		OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);

		/* kludge: *_cbc_remove_padding passes padding length in rr->type */
		orig_len = rr->length+((unsigned int)rr->type>>8);

		/* orig_len is the length of the record before any padding was
		 * removed. This is public information, as is the MAC in use,
		 * therefore we can safely process the record in a different
		 * amount of time if it's too short to possibly contain a MAC.
		 */
		if (orig_len < mac_size ||
		    /* CBC records must have a padding length byte too. */
		    (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
		     orig_len < mac_size+1))
			{
			al=SSL_AD_DECODE_ERROR;
			SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_LENGTH_TOO_SHORT);
			goto f_err;
			}

		if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE)
			{
			/* We update the length so that the TLS header bytes
			 * can be constructed correctly but we need to extract
			 * the MAC in constant time from within the record,
			 * without leaking the contents of the padding bytes.
			 * */
			mac = mac_tmp;
			ssl3_cbc_copy_mac(mac_tmp, rr, mac_size, orig_len);
			rr->length -= mac_size;
			}
		else
			{
			/* In this case there's no padding, so |orig_len|
			 * equals |rec->length| and we checked that there's
			 * enough bytes for |mac_size| above. */
			rr->length -= mac_size;
			mac = &rr->data[rr->length];
			}

		i=s->method->ssl3_enc->mac(s,md,0 /* not send */);
		if (i < 0 || mac == NULL || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
			enc_err = -1;
		if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH+mac_size)
			enc_err = -1;
		}

	if (enc_err < 0)
		{
		/* decryption failed, silently discard message */
		rr->length = 0;
		s->packet_length = 0;
		goto err;
		}

	/* r->length is now just compressed */
	if (s->expand != NULL)
		{
		if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH)
			{
			al=SSL_AD_RECORD_OVERFLOW;
			SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_COMPRESSED_LENGTH_TOO_LONG);
			goto f_err;
			}
		if (!ssl3_do_uncompress(s))
			{
			al=SSL_AD_DECOMPRESSION_FAILURE;
			SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_BAD_DECOMPRESSION);
			goto f_err;
			}
		}

	if (rr->length > SSL3_RT_MAX_PLAIN_LENGTH)
		{
		al=SSL_AD_RECORD_OVERFLOW;
		SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_DATA_LENGTH_TOO_LONG);
		goto f_err;
		}

	rr->off=0;
	/* So at this point the following is true
	 * ssl->s3->rrec.type 	is the type of record
	 * ssl->s3->rrec.length	== number of bytes in record
	 * ssl->s3->rrec.off	== offset to first valid byte
	 * ssl->s3->rrec.data	== where to take bytes from, increment
	 *			   after use :-).
	 */

	/* we have pulled in a full packet so zero things */
	s->packet_length=0;
	dtls1_record_bitmap_update(s, &(s->d1->bitmap));/* Mark receipt of record. */
	return(1);

f_err:
	ssl3_send_alert(s,SSL3_AL_FATAL,al);
err:
	return(0);
}


/* Call this to get a new input record.
 * It will return <= 0 if more data is needed, normally due to an error
 * or non-blocking IO.
 * When it finishes, one packet has been decoded and can be found in
 * ssl->s3->rrec.type    - is the type of record
 * ssl->s3->rrec.data, 	 - data
 * ssl->s3->rrec.length, - number of bytes
 */
/* used only by dtls1_read_bytes */
int dtls1_get_record(SSL *s)
	{
	int ssl_major,ssl_minor;
	int i,n;
	SSL3_RECORD *rr;
	unsigned char *p = NULL;
	unsigned short version;
	DTLS1_BITMAP *bitmap;
	unsigned int is_next_epoch;

	rr= &(s->s3->rrec);

	/* The epoch may have changed.  If so, process all the
	 * pending records.  This is a non-blocking operation. */
	dtls1_process_buffered_records(s);

	/* if we're renegotiating, then there may be buffered records */
	if (dtls1_get_processed_record(s))
		return 1;

	/* get something from the wire */
again:
	/* check if we have the header */
	if (	(s->rstate != SSL_ST_READ_BODY) ||
		(s->packet_length < DTLS1_RT_HEADER_LENGTH)) 
		{
		n=ssl3_read_n(s, DTLS1_RT_HEADER_LENGTH, s->s3->rbuf.len, 0);
		/* read timeout is handled by dtls1_read_bytes */
		if (n <= 0) return(n); /* error or non-blocking */

		/* this packet contained a partial record, dump it */
		if (s->packet_length != DTLS1_RT_HEADER_LENGTH)
			{
			s->packet_length = 0;
			goto again;
			}

		s->rstate=SSL_ST_READ_BODY;

		p=s->packet;

		/* Pull apart the header into the DTLS1_RECORD */
		rr->type= *(p++);
		ssl_major= *(p++);
		ssl_minor= *(p++);
		version=(ssl_major<<8)|ssl_minor;

		/* sequence number is 64 bits, with top 2 bytes = epoch */ 
		n2s(p,rr->epoch);

		memcpy(&(s->s3->read_sequence[2]), p, 6);
		p+=6;

		n2s(p,rr->length);

		/* Lets check version */
		if (!s->first_packet)
			{
			if (version != s->version)
				{
				/* unexpected version, silently discard */
				rr->length = 0;
				s->packet_length = 0;
				goto again;
				}
			}

		if ((version & 0xff00) != (s->version & 0xff00))
			{
			/* wrong version, silently discard record */
			rr->length = 0;
			s->packet_length = 0;
			goto again;
			}

		if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH)
			{
			/* record too long, silently discard it */
			rr->length = 0;
			s->packet_length = 0;
			goto again;
			}

		/* now s->rstate == SSL_ST_READ_BODY */
		}

	/* s->rstate == SSL_ST_READ_BODY, get and decode the data */

	if (rr->length > s->packet_length-DTLS1_RT_HEADER_LENGTH)
		{
		/* now s->packet_length == DTLS1_RT_HEADER_LENGTH */
		i=rr->length;
		n=ssl3_read_n(s,i,i,1);
		if (n <= 0) return(n); /* error or non-blocking io */

		/* this packet contained a partial record, dump it */
		if ( n != i)
			{
			rr->length = 0;
			s->packet_length = 0;
			goto again;
			}

		/* now n == rr->length,
		 * and s->packet_length == DTLS1_RT_HEADER_LENGTH + rr->length */
		}
	s->rstate=SSL_ST_READ_HEADER; /* set state for later operations */

	/* match epochs.  NULL means the packet is dropped on the floor */
	bitmap = dtls1_get_bitmap(s, rr, &is_next_epoch);
	if ( bitmap == NULL)
		{
		rr->length = 0;
		s->packet_length = 0;  /* dump this record */
		goto again;   /* get another record */
		}

#ifndef OPENSSL_NO_SCTP
	/* Only do replay check if no SCTP bio */
	if (!BIO_dgram_is_sctp(SSL_get_rbio(s)))
  		{
#endif
		/* Check whether this is a repeat, or aged record.
		 * Don't check if we're listening and this message is
		 * a ClientHello. They can look as if they're replayed,
		 * since they arrive from different connections and
		 * would be dropped unnecessarily.
		 */
		if (!(s->d1->listen && rr->type == SSL3_RT_HANDSHAKE &&
		    *p == SSL3_MT_CLIENT_HELLO) &&
		    !dtls1_record_replay_check(s, bitmap))
			{
			rr->length = 0;
			s->packet_length=0; /* dump this record */
			goto again;     /* get another record */
			}
#ifndef OPENSSL_NO_SCTP
  		}
#endif

	/* just read a 0 length packet */
	if (rr->length == 0) goto again;

	/* If this record is from the next epoch (either HM or ALERT),
	 * and a handshake is currently in progress, buffer it since it
	 * cannot be processed at this time. However, do not buffer
	 * anything while listening.
	 */
	if (is_next_epoch)
		{
		if ((SSL_in_init(s) || s->in_handshake) && !s->d1->listen)
			{
			dtls1_buffer_record(s, &(s->d1->unprocessed_rcds), rr->seq_num);
			}
		rr->length = 0;
		s->packet_length = 0;
		goto again;
		}

	if (!dtls1_process_record(s))
		{
		rr->length = 0;
		s->packet_length = 0;  /* dump this record */
		goto again;   /* get another record */
		}

	return(1);

	}

/* Return up to 'len' payload bytes received in 'type' records.
 * 'type' is one of the following:
 *
 *   -  SSL3_RT_HANDSHAKE (when ssl3_get_message calls us)
 *   -  SSL3_RT_APPLICATION_DATA (when ssl3_read calls us)
 *   -  0 (during a shutdown, no data has to be returned)
 *
 * If we don't have stored data to work from, read a SSL/TLS record first
 * (possibly multiple records if we still don't have anything to return).
 *
 * This function must handle any surprises the peer may have for us, such as
 * Alert records (e.g. close_notify), ChangeCipherSpec records (not really
 * a surprise, but handled as if it were), or renegotiation requests.
 * Also if record payloads contain fragments too small to process, we store
 * them until there is enough for the respective protocol (the record protocol
 * may use arbitrary fragmentation and even interleaving):
 *     Change cipher spec protocol
 *             just 1 byte needed, no need for keeping anything stored
 *     Alert protocol
 *             2 bytes needed (AlertLevel, AlertDescription)
 *     Handshake protocol
 *             4 bytes needed (HandshakeType, uint24 length) -- we just have
 *             to detect unexpected Client Hello and Hello Request messages
 *             here, anything else is handled by higher layers
 *     Application data protocol
 *             none of our business
 */
int dtls1_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek)
	{
	int al,i,j,ret;
	unsigned int n;
	SSL3_RECORD *rr;
	void (*cb)(const SSL *ssl,int type2,int val)=NULL;

	if (s->s3->rbuf.buf == NULL) /* Not initialized yet */
		if (!ssl3_setup_buffers(s))
			return(-1);

    /* XXX: check what the second '&& type' is about */
	if ((type && (type != SSL3_RT_APPLICATION_DATA) && 
		(type != SSL3_RT_HANDSHAKE) && type) ||
	    (peek && (type != SSL3_RT_APPLICATION_DATA)))
		{
		SSLerr(SSL_F_DTLS1_READ_BYTES, ERR_R_INTERNAL_ERROR);
		return -1;
		}

	/* check whether there's a handshake message (client hello?) waiting */
	if ( (ret = have_handshake_fragment(s, type, buf, len, peek)))
		return ret;

	/* Now s->d1->handshake_fragment_len == 0 if type == SSL3_RT_HANDSHAKE. */

#ifndef OPENSSL_NO_SCTP
	/* Continue handshake if it had to be interrupted to read
	 * app data with SCTP.
	 */
	if ((!s->in_handshake && SSL_in_init(s)) ||
	    (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
	     (s->state == DTLS1_SCTP_ST_SR_READ_SOCK || s->state == DTLS1_SCTP_ST_CR_READ_SOCK) &&
	     s->s3->in_read_app_data != 2))
#else
	if (!s->in_handshake && SSL_in_init(s))
#endif
		{
		/* type == SSL3_RT_APPLICATION_DATA */
		i=s->handshake_func(s);
		if (i < 0) return(i);
		if (i == 0)
			{
			SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_SSL_HANDSHAKE_FAILURE);
			return(-1);
			}
		}

start:
	s->rwstate=SSL_NOTHING;

	/* s->s3->rrec.type	    - is the type of record
	 * s->s3->rrec.data,    - data
	 * s->s3->rrec.off,     - offset into 'data' for next read
	 * s->s3->rrec.length,  - number of bytes. */
	rr = &(s->s3->rrec);

	/* We are not handshaking and have no data yet,
	 * so process data buffered during the last handshake
	 * in advance, if any.
	 */
	if (s->state == SSL_ST_OK && rr->length == 0)
		{
		pitem *item;
		item = pqueue_pop(s->d1->buffered_app_data.q);
		if (item)
			{
#ifndef OPENSSL_NO_SCTP
			/* Restore bio_dgram_sctp_rcvinfo struct */
			if (BIO_dgram_is_sctp(SSL_get_rbio(s)))
				{
				DTLS1_RECORD_DATA *rdata = (DTLS1_RECORD_DATA *) item->data;
				BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SCTP_SET_RCVINFO, sizeof(rdata->recordinfo), &rdata->recordinfo);
				}
#endif

			dtls1_copy_record(s, item);

			OPENSSL_free(item->data);
			pitem_free(item);
			}
		}

	/* Check for timeout */
	if (dtls1_handle_timeout(s) > 0)
		goto start;

	/* get new packet if necessary */
	if ((rr->length == 0) || (s->rstate == SSL_ST_READ_BODY))
		{
		ret=dtls1_get_record(s);
		if (ret <= 0) 
			{
			ret = dtls1_read_failed(s, ret);
			/* anything other than a timeout is an error */
			if (ret <= 0)  
				return(ret);
			else
				goto start;
			}
		}

	if (s->d1->listen && rr->type != SSL3_RT_HANDSHAKE)
		{
		rr->length = 0;
		goto start;
		}

	/* we now have a packet which can be read and processed */

	if (s->s3->change_cipher_spec /* set when we receive ChangeCipherSpec,
	                               * reset by ssl3_get_finished */
		&& (rr->type != SSL3_RT_HANDSHAKE))
		{
		/* We now have application data between CCS and Finished.
		 * Most likely the packets were reordered on their way, so
		 * buffer the application data for later processing rather
		 * than dropping the connection.
		 */
		dtls1_buffer_record(s, &(s->d1->buffered_app_data), rr->seq_num);
		rr->length = 0;
		goto start;
		}

	/* If the other end has shut down, throw anything we read away
	 * (even in 'peek' mode) */
	if (s->shutdown & SSL_RECEIVED_SHUTDOWN)
		{
		rr->length=0;
		s->rwstate=SSL_NOTHING;
		return(0);
		}


	if (type == rr->type) /* SSL3_RT_APPLICATION_DATA or SSL3_RT_HANDSHAKE */
		{
		/* make sure that we are not getting application data when we
		 * are doing a handshake for the first time */
		if (SSL_in_init(s) && (type == SSL3_RT_APPLICATION_DATA) &&
			(s->enc_read_ctx == NULL))
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_APP_DATA_IN_HANDSHAKE);
			goto f_err;
			}

		if (len <= 0) return(len);

		if ((unsigned int)len > rr->length)
			n = rr->length;
		else
			n = (unsigned int)len;

		memcpy(buf,&(rr->data[rr->off]),n);
		if (!peek)
			{
			rr->length-=n;
			rr->off+=n;
			if (rr->length == 0)
				{
				s->rstate=SSL_ST_READ_HEADER;
				rr->off=0;
				}
			}

#ifndef OPENSSL_NO_SCTP
			/* We were about to renegotiate but had to read
			 * belated application data first, so retry.
			 */
			if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
			    rr->type == SSL3_RT_APPLICATION_DATA &&
			    (s->state == DTLS1_SCTP_ST_SR_READ_SOCK || s->state == DTLS1_SCTP_ST_CR_READ_SOCK))
				{
				s->rwstate=SSL_READING;
				BIO_clear_retry_flags(SSL_get_rbio(s));
				BIO_set_retry_read(SSL_get_rbio(s));
				}

			/* We might had to delay a close_notify alert because
			 * of reordered app data. If there was an alert and there
			 * is no message to read anymore, finally set shutdown.
			 */
			if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
			    s->d1->shutdown_received && !BIO_dgram_sctp_msg_waiting(SSL_get_rbio(s)))
				{
				s->shutdown |= SSL_RECEIVED_SHUTDOWN;
				return(0);
				}
#endif			
		return(n);
		}


	/* If we get here, then type != rr->type; if we have a handshake
	 * message, then it was unexpected (Hello Request or Client Hello). */

	/* In case of record types for which we have 'fragment' storage,
	 * fill that so that we can process the data at a fixed place.
	 */
		{
		unsigned int k, dest_maxlen = 0;
		unsigned char *dest = NULL;
		unsigned int *dest_len = NULL;

		if (rr->type == SSL3_RT_HANDSHAKE)
			{
			dest_maxlen = sizeof s->d1->handshake_fragment;
			dest = s->d1->handshake_fragment;
			dest_len = &s->d1->handshake_fragment_len;
			}
		else if (rr->type == SSL3_RT_ALERT)
			{
			dest_maxlen = sizeof(s->d1->alert_fragment);
			dest = s->d1->alert_fragment;
			dest_len = &s->d1->alert_fragment_len;
			}
#ifndef OPENSSL_NO_HEARTBEATS
		else if (rr->type == TLS1_RT_HEARTBEAT)
			{
			dtls1_process_heartbeat(s);

			/* Exit and notify application to read again */
			rr->length = 0;
			s->rwstate=SSL_READING;
			BIO_clear_retry_flags(SSL_get_rbio(s));
			BIO_set_retry_read(SSL_get_rbio(s));
			return(-1);
			}
#endif
		/* else it's a CCS message, or application data or wrong */
		else if (rr->type != SSL3_RT_CHANGE_CIPHER_SPEC)
			{
			/* Application data while renegotiating
			 * is allowed. Try again reading.
			 */
			if (rr->type == SSL3_RT_APPLICATION_DATA)
				{
				BIO *bio;
				s->s3->in_read_app_data=2;
				bio=SSL_get_rbio(s);
				s->rwstate=SSL_READING;
				BIO_clear_retry_flags(bio);
				BIO_set_retry_read(bio);
				return(-1);
				}

			/* Not certain if this is the right error handling */
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_UNEXPECTED_RECORD);
			goto f_err;
			}