d1_pkt.c

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/* ssl/d1_pkt.c */
/* 
 * DTLS implementation written by Nagendra Modadugu
 * ([email protected]) 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
 *    [email protected].
 *
 * 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
 * ([email protected]).  This product includes software written by Tim
 * Hudson ([email protected]).
 *
 */
/* Copyright (C) 1995-1998 Eric Young ([email protected])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([email protected]).
 * 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 ([email protected]).
 * 
 * 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 ([email protected])"
 *    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 ([email protected])"
 * 
 * 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

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

    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);
        }
    
    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 clear=0;
    int enc_err;
    SSL_SESSION *sess;
    SSL3_RECORD *rr;
    unsigned int mac_size;
    unsigned char md[EVP_MAX_MD_SIZE];
    int decryption_failed_or_bad_record_mac = 0;
    unsigned char *mac = NULL;


    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);
    if (enc_err <= 0)
        {
        /* To minimize information leaked via timing, we will always
         * perform all computations before discarding the message.
         */
        decryption_failed_or_bad_record_mac = 1;
        }

#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) ||
        (s->read_hash == NULL))
        clear=1;

    if (!clear)
        {
        /* !clear => s->read_hash != NULL => mac_size != -1 */
        int t;
        t=EVP_MD_CTX_size(s->read_hash);
        OPENSSL_assert(t >= 0);
        mac_size=t;

        if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH+mac_size)
            {
#if 0 /* OK only for stream ciphers (then rr->length is visible from ciphertext anyway) */
            al=SSL_AD_RECORD_OVERFLOW;
            SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_PRE_MAC_LENGTH_TOO_LONG);
            goto f_err;
#else
            decryption_failed_or_bad_record_mac = 1;
#endif          
            }
        /* check the MAC for rr->input (it's in mac_size bytes at the tail) */
        if (rr->length >= mac_size)
            {
            rr->length -= mac_size;
            mac = &rr->data[rr->length];
            }
        else
            rr->length = 0;
        i=s->method->ssl3_enc->mac(s,md,0);
        if (i < 0 || mac == NULL || memcmp(md, mac, mac_size) != 0)
            {
            decryption_failed_or_bad_record_mac = 1;
            }
        }

    if (decryption_failed_or_bad_record_mac)
        {
        /* 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;
            }
        }

    /* 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;
            }

        if (dest_maxlen > 0)
            {
            /* XDTLS:  In a pathalogical case, the Client Hello
             *  may be fragmented--don't always expect dest_maxlen bytes */
            if ( rr->length < dest_maxlen)
                {
#ifdef DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
                /*
                 * for normal alerts rr->length is 2, while
                 * dest_maxlen is 7 if we were to handle this
                 * non-existing alert...
                 */
                FIX ME
#endif
                s->rstate=SSL_ST_READ_HEADER;
                rr->length = 0;
                goto start;
                }

            /* now move 'n' bytes: */
            for ( k = 0; k < dest_maxlen; k++)
                {
                dest[k] = rr->data[rr->off++];
                rr->length--;
                }
            *dest_len = dest_maxlen;
            }
        }

    /* s->d1->handshake_fragment_len == 12  iff  rr->type == SSL3_RT_HANDSHAKE;
     * s->d1->alert_fragment_len == 7      iff  rr->type == SSL3_RT_ALERT.
     * (Possibly rr is 'empty' now, i.e. rr->length may be 0.) */

    /* If we are a client, check for an incoming 'Hello Request': */
    if ((!s->server) &&
        (s->d1->handshake_fragment_len >= DTLS1_HM_HEADER_LENGTH) &&
        (s->d1->handshake_fragment[0] == SSL3_MT_HELLO_REQUEST) &&
        (s->session != NULL) && (s->session->cipher != NULL))
        {
        s->d1->handshake_fragment_len = 0;

        if ((s->d1->handshake_fragment[1] != 0) ||
            (s->d1->handshake_fragment[2] != 0) ||
            (s->d1->handshake_fragment[3] != 0))
            {
            al=SSL_AD_DECODE_ERROR;
            SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_BAD_HELLO_REQUEST);
            goto err;
            }

        /* no need to check sequence number on HELLO REQUEST messages */

        if (s->msg_callback)
            s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, 
                s->d1->handshake_fragment, 4, s, s->msg_callback_arg);

        if (SSL_is_init_finished(s) &&
            !(s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS) &&
            !s->s3->renegotiate)
            {
            s->new_session = 1;
            ssl3_renegotiate(s);
            if (ssl3_renegotiate_check(s))
                {
                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);
                    }

                if (!(s->mode & SSL_MODE_AUTO_RETRY))
                    {
                    if (s->s3->rbuf.left == 0) /* no read-ahead left? */
                        {
                        BIO *bio;
                        /* In the case where we try to read application data,
                         * but we trigger an SSL handshake, we return -1 with
                         * the retry option set.  Otherwise renegotiation may
                         * cause nasty problems in the blocking world */
                        s->rwstate=SSL_READING;
                        bio=SSL_get_rbio(s);
                        BIO_clear_retry_flags(bio);
                        BIO_set_retry_read(bio);
                        return(-1);
                        }
                    }
                }
            }
        /* we either finished a handshake or ignored the request,
         * now try again to obtain the (application) data we were asked for */
        goto start;
        }

    if (s->d1->alert_fragment_len >= DTLS1_AL_HEADER_LENGTH)
        {
        int alert_level = s->d1->alert_fragment[0];
        int alert_descr = s->d1->alert_fragment[1];

        s->d1->alert_fragment_len = 0;

        if (s->msg_callback)
            s->msg_callback(0, s->version, SSL3_RT_ALERT, 
                s->d1->alert_fragment, 2, s, s->msg_callback_arg);

        if (s->info_callback != NULL)
            cb=s->info_callback;
        else if (s->ctx->info_callback != NULL)
            cb=s->ctx->info_callback;

        if (cb != NULL)
            {
            j = (alert_level << 8) | alert_descr;
            cb(s, SSL_CB_READ_ALERT, j);
            }

        if (alert_level == 1) /* warning */
            {
            s->s3->warn_alert = alert_descr;
            if (alert_descr == SSL_AD_CLOSE_NOTIFY)
                {
#ifndef OPENSSL_NO_SCTP
                /* With SCTP and streams the socket may deliver app data
                 * after a close_notify alert. We have to check this
                 * first so that nothing gets discarded.
                 */
                if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
                    BIO_dgram_sctp_msg_waiting(SSL_get_rbio(s)))
                    {
                    s->d1->shutdown_received = 1;
                    s->rwstate=SSL_READING;
                    BIO_clear_retry_flags(SSL_get_rbio(s));
                    BIO_set_retry_read(SSL_get_rbio(s));
                    return -1;
                    }
#endif
                s->shutdown |= SSL_RECEIVED_SHUTDOWN;
                return(0);
                }
#if 0
            /* XXX: this is a possible improvement in the future */
            /* now check if it's a missing record */
            if (alert_descr == DTLS1_AD_MISSING_HANDSHAKE_MESSAGE)
                {
                unsigned short seq;
                unsigned int frag_off;
                unsigned char *p = &(s->d1->alert_fragment[2]);

                n2s(p, seq);
                n2l3(p, frag_off);

                dtls1_retransmit_message(s,
                                         dtls1_get_queue_priority(frag->msg_header.seq, 0),
                                         frag_off, &found);
                if ( ! found  && SSL_in_init(s))
                    {
                    /* fprintf( stderr,"in init = %d\n", SSL_in_init(s)); */
                    /* requested a message not yet sent, 
                       send an alert ourselves */
                    ssl3_send_alert(s,SSL3_AL_WARNING,
                        DTLS1_AD_MISSING_HANDSHAKE_MESSAGE);
                    }
                }
#endif
            }
        else if (alert_level == 2) /* fatal */
            {
            char tmp[16];

            s->rwstate=SSL_NOTHING;
            s->s3->fatal_alert = alert_descr;
            SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_AD_REASON_OFFSET + alert_descr);
            BIO_snprintf(tmp,sizeof tmp,"%d",alert_descr);
            ERR_add_error_data(2,"SSL alert number ",tmp);
            s->shutdown|=SSL_RECEIVED_SHUTDOWN;
            SSL_CTX_remove_session(s->ctx,s->session);
            return(0);
            }
        else
            {
            al=SSL_AD_ILLEGAL_PARAMETER;
            SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_UNKNOWN_ALERT_TYPE);
            goto f_err;
            }

        goto start;
        }

    if (s->shutdown & SSL_SENT_SHUTDOWN) /* but we have not received a shutdown */
        {
        s->rwstate=SSL_NOTHING;
        rr->length=0;
        return(0);
        }

    if (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC)
        {
        struct ccs_header_st ccs_hdr;
        unsigned int ccs_hdr_len = DTLS1_CCS_HEADER_LENGTH;

        dtls1_get_ccs_header(rr->data, &ccs_hdr);

        if (s->version == DTLS1_BAD_VER)
            ccs_hdr_len = 3;

        /* 'Change Cipher Spec' is just a single byte, so we know
         * exactly what the record payload has to look like */
        /* XDTLS: check that epoch is consistent */
        if (    (rr->length != ccs_hdr_len) || 
            (rr->off != 0) || (rr->data[0] != SSL3_MT_CCS))
            {
            i=SSL_AD_ILLEGAL_PARAMETER;
            SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_BAD_CHANGE_CIPHER_SPEC);
            goto err;
            }

        rr->length=0;

        if (s->msg_callback)
            s->msg_callback(0, s->version, SSL3_RT_CHANGE_CIPHER_SPEC, 
                rr->data, 1, s, s->msg_callback_arg);

        /* We can't process a CCS now, because previous handshake
         * messages are still missing, so just drop it.
         */
        if (!s->d1->change_cipher_spec_ok)
            {
            goto start;
            }

        s->d1->change_cipher_spec_ok = 0;

        s->s3->change_cipher_spec=1;
        if (!ssl3_do_change_cipher_spec(s))
            goto err;

        /* do this whenever CCS is processed */
        dtls1_reset_seq_numbers(s, SSL3_CC_READ);

        if (s->version == DTLS1_BAD_VER)
            s->d1->handshake_read_seq++;

#ifndef OPENSSL_NO_SCTP
        /* Remember that a CCS has been received,
         * so that an old key of SCTP-Auth can be
         * deleted when a CCS is sent. Will be ignored
         * if no SCTP is used
         */
        BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_AUTH_CCS_RCVD, 1, NULL);
#endif

        goto start;
        }

    /* Unexpected handshake message (Client Hello, or protocol violation) */
    if ((s->d1->handshake_fragment_len >= DTLS1_HM_HEADER_LENGTH) && 
        !s->in_handshake)
        {
        struct hm_header_st msg_hdr;
        
        /* this may just be a stale retransmit */
        dtls1_get_message_header(rr->data, &msg_hdr);
        if( rr->epoch != s->d1->r_epoch)
            {
            rr->length = 0;
            goto start;
            }

        /* If we are server, we may have a repeated FINISHED of the
         * client here, then retransmit our CCS and FINISHED.
         */
        if (msg_hdr.type == SSL3_MT_FINISHED)
            {
            if (dtls1_check_timeout_num(s) < 0)
                return -1;

            dtls1_retransmit_buffered_messages(s);
            rr->length = 0;
            goto start;
            }

        if (((s->state&SSL_ST_MASK) == SSL_ST_OK) &&
            !(s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS))
            {
#if 0 /* worked only because C operator preferences are not as expected (and
       * because this is not really needed for clients except for detecting
       * protocol violations): */
            s->state=SSL_ST_BEFORE|(s->server)
                ?SSL_ST_ACCEPT
                :SSL_ST_CONNECT;
#else
            s->state = s->server ? SSL_ST_ACCEPT : SSL_ST_CONNECT;
#endif
            s->renegotiate=1;
            s->new_session=1;
            }
        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);
            }

        if (!(s->mode & SSL_MODE_AUTO_RETRY))
            {
            if (s->s3->rbuf.left == 0) /* no read-ahead left? */
                {
                BIO *bio;
                /* In the case where we try to read application data,
                 * but we trigger an SSL handshake, we return -1 with
                 * the retry option set.  Otherwise renegotiation may
                 * cause nasty problems in the blocking world */
                s->rwstate=SSL_READING;
                bio=SSL_get_rbio(s);
                BIO_clear_retry_flags(bio);
                BIO_set_retry_read(bio);
                return(-1);
                }
            }
        goto start;
        }

    switch (rr->type)
        {
    default:
#ifndef OPENSSL_NO_TLS
        /* TLS just ignores unknown message types */
        if (s->version == TLS1_VERSION)
            {
            rr->length = 0;
            goto start;
            }
#endif
        al=SSL_AD_UNEXPECTED_MESSAGE;
        SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_UNEXPECTED_RECORD);
        goto f_err;
    case SSL3_RT_CHANGE_CIPHER_SPEC:
    case SSL3_RT_ALERT:
    case SSL3_RT_HANDSHAKE:
        /* we already handled all of these, with the possible exception
         * of SSL3_RT_HANDSHAKE when s->in_handshake is set, but that
         * should not happen when type != rr->type */
        al=SSL_AD_UNEXPECTED_MESSAGE;
        SSLerr(SSL_F_DTLS1_READ_BYTES,ERR_R_INTERNAL_ERROR);
        goto f_err;
    case SSL3_RT_APPLICATION_DATA:
        /* At this point, we were expecting handshake data,
         * but have application data.  If the library was
         * running inside ssl3_read() (i.e. in_read_app_data
         * is set) and it makes sense to read application data
         * at this point (session renegotiation not yet started),
         * we will indulge it.
         */
        if (s->s3->in_read_app_data &&
            (s->s3->total_renegotiations != 0) &&
            ((
                (s->state & SSL_ST_CONNECT) &&
                (s->state >= SSL3_ST_CW_CLNT_HELLO_A) &&
                (s->state <= SSL3_ST_CR_SRVR_HELLO_A)
                ) || (
                    (s->state & SSL_ST_ACCEPT) &&
                    (s->state <= SSL3_ST_SW_HELLO_REQ_A) &&
                    (s->state >= SSL3_ST_SR_CLNT_HELLO_A)
                    )
                ))
            {
            s->s3->in_read_app_data=2;
            return(-1);
            }
        else
            {
            al=SSL_AD_UNEXPECTED_MESSAGE;
            SSLerr(SSL_F_DTLS1_READ_BYTES,SSL_R_UNEXPECTED_RECORD);
            goto f_err;
            }
        }
    /* not reached */

f_err:
    ssl3_send_alert(s,SSL3_AL_FATAL,al);
err:
    return(-1);
    }

int
dtls1_write_app_data_bytes(SSL *s, int type, const void *buf_, int len)
    {
    int i;

#ifndef OPENSSL_NO_SCTP
        /* Check if we have to continue an interrupted handshake
         * for reading belated app data with SCTP.
         */
        if ((SSL_in_init(s) && !s->in_handshake) ||
            (BIO_dgram_is_sctp(SSL_get_wbio(s)) &&
             (s->state == DTLS1_SCTP_ST_SR_READ_SOCK || s->state == DTLS1_SCTP_ST_CR_READ_SOCK)))
#else
        if (SSL_in_init(s) && !s->in_handshake)
#endif
        {
        i=s->handshake_func(s);
        if (i < 0) return(i);
        if (i == 0)
            {
            SSLerr(SSL_F_DTLS1_WRITE_APP_DATA_BYTES,SSL_R_SSL_HANDSHAKE_FAILURE);
            return -1;
            }
        }

    if (len > SSL3_RT_MAX_PLAIN_LENGTH)
        {
            SSLerr(SSL_F_DTLS1_WRITE_APP_DATA_BYTES,SSL_R_DTLS_MESSAGE_TOO_BIG);
            return -1;
        }

    i = dtls1_write_bytes(s, type, buf_, len);
    return i;
    }


    /* this only happens when a client hello is received and a handshake 
     * is started. */
static int
have_handshake_fragment(SSL *s, int type, unsigned char *buf, 
    int len, int peek)
    {
    
    if ((type == SSL3_RT_HANDSHAKE) && (s->d1->handshake_fragment_len > 0))
        /* (partially) satisfy request from storage */
        {
        unsigned char *src = s->d1->handshake_fragment;
        unsigned char *dst = buf;
        unsigned int k,n;
        
        /* peek == 0 */
        n = 0;
        while ((len > 0) && (s->d1->handshake_fragment_len > 0))
            {
            *dst++ = *src++;
            len--; s->d1->handshake_fragment_len--;
            n++;
            }
        /* move any remaining fragment bytes: */
        for (k = 0; k < s->d1->handshake_fragment_len; k++)
            s->d1->handshake_fragment[k] = *src++;
        return n;
        }
    
    return 0;
    }




/* Call this to write data in records of type 'type'
 * It will return <= 0 if not all data has been sent or non-blocking IO.
 */
int dtls1_write_bytes(SSL *s, int type, const void *buf, int len)
    {
    int i;

    OPENSSL_assert(len <= SSL3_RT_MAX_PLAIN_LENGTH);
    s->rwstate=SSL_NOTHING;
    i=do_dtls1_write(s, type, buf, len, 0);
    return i;
    }

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);
        if (mac_size < 0)
            goto err;
        }

    /* 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 && SSL_version(s) != DTLS1_BAD_VER)
        {
        /* 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)
        {
        if(s->method->ssl3_enc->mac(s,&(p[wr->length + bs]),1) < 0)
            goto err;
        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 */
    if (bs) /* bs != 0 in case of CBC */
        {
        RAND_pseudo_bytes(p,bs);
        /* master IV and last CBC residue stand for
         * the rest of randomness */
        wr->length += bs;
        }

    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;
    }



static int dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap)
    {
    int cmp;
    unsigned int shift;
    const unsigned char *seq = s->s3->read_sequence;

    cmp = satsub64be(seq,bitmap->max_seq_num);
    if (cmp > 0)
        {
        memcpy (s->s3->rrec.seq_num,seq,8);
        return 1; /* this record in new */
        }
    shift = -cmp;
    if (shift >= sizeof(bitmap->map)*8)
        return 0; /* stale, outside the window */
    else if (bitmap->map & (1UL<<shift))
        return 0; /* record previously received */

    memcpy (s->s3->rrec.seq_num,seq,8);
    return 1;
    }


static void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap)
    {
    int cmp;
    unsigned int shift;
    const unsigned char *seq = s->s3->read_sequence;

    cmp = satsub64be(seq,bitmap->max_seq_num);
    if (cmp > 0)
        {
        shift = cmp;
        if (shift < sizeof(bitmap->map)*8)
            bitmap->map <<= shift, bitmap->map |= 1UL;
        else
            bitmap->map = 1UL;
        memcpy(bitmap->max_seq_num,seq,8);
        }
    else    {
        shift = -cmp;
        if (shift < sizeof(bitmap->map)*8)
            bitmap->map |= 1UL<<shift;
        }
    }


int dtls1_dispatch_alert(SSL *s)
    {
    int i,j;
    void (*cb)(const SSL *ssl,int type,int val)=NULL;
    unsigned char buf[DTLS1_AL_HEADER_LENGTH];
    unsigned char *ptr = &buf[0];

    s->s3->alert_dispatch=0;

    memset(buf, 0x00, sizeof(buf));
    *ptr++ = s->s3->send_alert[0];
    *ptr++ = s->s3->send_alert[1];

#ifdef DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
    if (s->s3->send_alert[1] == DTLS1_AD_MISSING_HANDSHAKE_MESSAGE)
        {   
        s2n(s->d1->handshake_read_seq, ptr);
#if 0
        if ( s->d1->r_msg_hdr.frag_off == 0)  /* waiting for a new msg */

        else
            s2n(s->d1->r_msg_hdr.seq, ptr); /* partial msg read */
#endif

#if 0
        fprintf(stderr, "s->d1->handshake_read_seq = %d, s->d1->r_msg_hdr.seq = %d\n",s->d1->handshake_read_seq,s->d1->r_msg_hdr.seq);
#endif
        l2n3(s->d1->r_msg_hdr.frag_off, ptr);
        }
#endif

    i = do_dtls1_write(s, SSL3_RT_ALERT, &buf[0], sizeof(buf), 0);
    if (i <= 0)
        {
        s->s3->alert_dispatch=1;
        /* fprintf( stderr, "not done with alert\n" ); */
        }
    else
        {
        if (s->s3->send_alert[0] == SSL3_AL_FATAL
#ifdef DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
            || s->s3->send_alert[1] == DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
#endif
            )
            (void)BIO_flush(s->wbio);

        if (s->msg_callback)
            s->msg_callback(1, s->version, SSL3_RT_ALERT, s->s3->send_alert, 
                2, s, s->msg_callback_arg);

        if (s->info_callback != NULL)
            cb=s->info_callback;
        else if (s->ctx->info_callback != NULL)
            cb=s->ctx->info_callback;

        if (cb != NULL)
            {
            j=(s->s3->send_alert[0]<<8)|s->s3->send_alert[1];
            cb(s,SSL_CB_WRITE_ALERT,j);
            }
        }
    return(i);
    }


static DTLS1_BITMAP *
dtls1_get_bitmap(SSL *s, SSL3_RECORD *rr, unsigned int *is_next_epoch)
    {
    
    *is_next_epoch = 0;

    /* In current epoch, accept HM, CCS, DATA, & ALERT */
    if (rr->epoch == s->d1->r_epoch)
        return &s->d1->bitmap;

    /* Only HM and ALERT messages can be from the next epoch */
    else if (rr->epoch == (unsigned long)(s->d1->r_epoch + 1) &&
        (rr->type == SSL3_RT_HANDSHAKE ||
            rr->type == SSL3_RT_ALERT))
        {
        *is_next_epoch = 1;
        return &s->d1->next_bitmap;
        }

    return NULL;
    }

#if 0
static int
dtls1_record_needs_buffering(SSL *s, SSL3_RECORD *rr, unsigned short *priority,
    unsigned long *offset)
    {

    /* alerts are passed up immediately */
    if ( rr->type == SSL3_RT_APPLICATION_DATA ||
        rr->type == SSL3_RT_ALERT)
        return 0;

    /* Only need to buffer if a handshake is underway.
     * (this implies that Hello Request and Client Hello are passed up
     * immediately) */
    if ( SSL_in_init(s))
        {
        unsigned char *data = rr->data;
        /* need to extract the HM/CCS sequence number here */
        if ( rr->type == SSL3_RT_HANDSHAKE ||
            rr->type == SSL3_RT_CHANGE_CIPHER_SPEC)
            {
            unsigned short seq_num;
            struct hm_header_st msg_hdr;
            struct ccs_header_st ccs_hdr;

            if ( rr->type == SSL3_RT_HANDSHAKE)
                {
                dtls1_get_message_header(data, &msg_hdr);
                seq_num = msg_hdr.seq;
                *offset = msg_hdr.frag_off;
                }
            else
                {
                dtls1_get_ccs_header(data, &ccs_hdr);
                seq_num = ccs_hdr.seq;
                *offset = 0;
                }
                
            /* this is either a record we're waiting for, or a
             * retransmit of something we happened to previously 
             * receive (higher layers will drop the repeat silently */
            if ( seq_num < s->d1->handshake_read_seq)
                return 0;
            if (rr->type == SSL3_RT_HANDSHAKE && 
                seq_num == s->d1->handshake_read_seq &&
                msg_hdr.frag_off < s->d1->r_msg_hdr.frag_off)
                return 0;
            else if ( seq_num == s->d1->handshake_read_seq &&
                (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC ||
                    msg_hdr.frag_off == s->d1->r_msg_hdr.frag_off))
                return 0;
            else
                {
                *priority = seq_num;
                return 1;
                }
            }
        else /* unknown record type */
            return 0;
        }

    return 0;
    }
#endif

void
dtls1_reset_seq_numbers(SSL *s, int rw)
    {
    unsigned char *seq;
    unsigned int seq_bytes = sizeof(s->s3->read_sequence);

    if ( rw & SSL3_CC_READ)
        {
        seq = s->s3->read_sequence;
        s->d1->r_epoch++;
        memcpy(&(s->d1->bitmap), &(s->d1->next_bitmap), sizeof(DTLS1_BITMAP));
        memset(&(s->d1->next_bitmap), 0x00, sizeof(DTLS1_BITMAP));
        }
    else
        {
        seq = s->s3->write_sequence;
        memcpy(s->d1->last_write_sequence, seq, sizeof(s->s3->write_sequence));
        s->d1->w_epoch++;
        }

    memset(seq, 0x00, seq_bytes);
    }