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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>

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,
      PQ_64BIT *seq_num);
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,
      PQ_64BIT *priority);
static int dtls1_process_record(SSL *s);
#if PQ_64BIT_IS_INTEGER
static PQ_64BIT bytes_to_long_long(unsigned char *bytes, PQ_64BIT *num);
#endif
static void dtls1_clear_timeouts(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, PQ_64BIT *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;

      /* 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)
        {
        DTLS1_RECORD_DATA *rdata;
        rdata = (DTLS1_RECORD_DATA *)item->data;
        
        /* 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];


      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)
            {
            if (enc_err == 0)
                  /* SSLerr() and ssl3_send_alert() have been called */
                  goto err;

            /* otherwise enc_err == -1 */
            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) ||
            (s->read_hash == NULL))
    clear=1;

      if (!clear)
            {
            mac_size=EVP_MD_size(s->read_hash);

            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
                  goto err;
#endif                  
                  }
            /* check the MAC for rr->input (it's in mac_size bytes at the tail) */
            if (rr->length < mac_size)
                  {
#if 0 /* OK only for stream ciphers */
                  al=SSL_AD_DECODE_ERROR;
                  SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_LENGTH_TOO_SHORT);
                  goto f_err;
#else
                  goto err;
#endif
                  }
            rr->length-=mac_size;
            i=s->method->ssl3_enc->mac(s,md,0);
            if (memcmp(md,&(rr->data[rr->length]),mac_size) != 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;
      SSL_SESSION *sess;
      unsigned char *p = NULL;
      unsigned short version;
      DTLS1_BITMAP *bitmap;
      unsigned int is_next_epoch;

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

    /* 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 && version != DTLS1_BAD_VER)
                        {
                        /* unexpected version, silently discard */
                        rr->length = 0;
                        s->packet_length = 0;
                        goto again;
                        }
                  }

            if ((version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
                (version & 0xff00) != (DTLS1_BAD_VER & 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;
                  }

            s->client_version = version;
            /* 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 */
            }

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

      /* 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. */
      if (is_next_epoch)
            {
            if (SSL_in_init(s) || s->in_handshake)
                  {
                  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 */
            }

      dtls1_clear_timeouts(s);  /* done waiting */
      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. */

      if (!s->in_handshake && SSL_in_init(s))
            {
            /* 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)
                  {
                  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;
                        }
                  }
            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;
                  }
            /* 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)
                  {
                  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)
                        {
                        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);

            /* '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 (s->client_version == DTLS1_BAD_VER || s->version == DTLS1_BAD_VER)
                  ccs_hdr_len = 3;

            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->client_version == DTLS1_BAD_VER)
                  s->d1->handshake_read_seq++;

            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)
                  {
                  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->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;

      if (SSL_in_init(s) && !s->in_handshake)
            {
            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) ||
            (s->write_hash == NULL))
            clear=1;

      if (clear)
            mac_size=0;
      else
            mac_size=EVP_MD_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 && 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;

      if (s->client_version == DTLS1_BAD_VER)
            *(p++) = DTLS1_BAD_VER>>8,
            *(p++) = DTLS1_BAD_VER&0xff;
      else
            *(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 */
      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,
      PQ_64BIT *seq_num)
      {
#if PQ_64BIT_IS_INTEGER
      PQ_64BIT mask = 0x0000000000000001L;
#endif
      PQ_64BIT rcd_num, tmp;

      pq_64bit_init(&rcd_num);
      pq_64bit_init(&tmp);

      /* this is the sequence number for the record just read */
      pq_64bit_bin2num(&rcd_num, s->s3->read_sequence, 8);

      
      if (pq_64bit_gt(&rcd_num, &(bitmap->max_seq_num)) ||
            pq_64bit_eq(&rcd_num, &(bitmap->max_seq_num)))
            {
            pq_64bit_assign(seq_num, &rcd_num);
            pq_64bit_free(&rcd_num);
            pq_64bit_free(&tmp);
            return 1;  /* this record is new */
            }

      pq_64bit_sub(&tmp, &(bitmap->max_seq_num), &rcd_num);

      if ( pq_64bit_get_word(&tmp) > bitmap->length)
            {
            pq_64bit_free(&rcd_num);
            pq_64bit_free(&tmp);
            return 0;  /* stale, outside the window */
            }

#if PQ_64BIT_IS_BIGNUM
      {
      int offset;
      pq_64bit_sub(&tmp, &(bitmap->max_seq_num), &rcd_num);
      pq_64bit_sub_word(&tmp, 1);
      offset = pq_64bit_get_word(&tmp);
      if ( pq_64bit_is_bit_set(&(bitmap->map), offset))
            {
            pq_64bit_free(&rcd_num);
            pq_64bit_free(&tmp);
            return 0;
            }
      }
#else
      mask <<= (bitmap->max_seq_num - rcd_num - 1);
      if (bitmap->map & mask)
            return 0; /* record previously received */
#endif
      
      pq_64bit_assign(seq_num, &rcd_num);
      pq_64bit_free(&rcd_num);
      pq_64bit_free(&tmp);
      return 1;
      }


static void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap)
      {
      unsigned int shift;
      PQ_64BIT rcd_num;
      PQ_64BIT tmp;
      PQ_64BIT_CTX *ctx;

      pq_64bit_init(&rcd_num);
      pq_64bit_init(&tmp);

      pq_64bit_bin2num(&rcd_num, s->s3->read_sequence, 8);

      /* unfortunate code complexity due to 64-bit manipulation support
       * on 32-bit machines */
      if ( pq_64bit_gt(&rcd_num, &(bitmap->max_seq_num)) ||
            pq_64bit_eq(&rcd_num, &(bitmap->max_seq_num)))
            {
            pq_64bit_sub(&tmp, &rcd_num, &(bitmap->max_seq_num));
            pq_64bit_add_word(&tmp, 1);

            shift = (unsigned int)pq_64bit_get_word(&tmp);

            pq_64bit_lshift(&(tmp), &(bitmap->map), shift);
            pq_64bit_assign(&(bitmap->map), &tmp);

            pq_64bit_set_bit(&(bitmap->map), 0);
            pq_64bit_add_word(&rcd_num, 1);
            pq_64bit_assign(&(bitmap->max_seq_num), &rcd_num);

            pq_64bit_assign_word(&tmp, 1);
            pq_64bit_lshift(&tmp, &tmp, bitmap->length);
            ctx = pq_64bit_ctx_new(&ctx);
            pq_64bit_mod(&(bitmap->map), &(bitmap->map), &tmp, ctx);
            pq_64bit_ctx_free(ctx);
            }
      else
            {
            pq_64bit_sub(&tmp, &(bitmap->max_seq_num), &rcd_num);
            pq_64bit_sub_word(&tmp, 1);
            shift = (unsigned int)pq_64bit_get_word(&tmp);

            pq_64bit_set_bit(&(bitmap->map), shift);
            }

      pq_64bit_free(&rcd_num);
      pq_64bit_free(&tmp);
      }


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++;

            pq_64bit_assign(&(s->d1->bitmap.map), &(s->d1->next_bitmap.map));
            s->d1->bitmap.length = s->d1->next_bitmap.length;
            pq_64bit_assign(&(s->d1->bitmap.max_seq_num), 
                  &(s->d1->next_bitmap.max_seq_num));

            pq_64bit_free(&(s->d1->next_bitmap.map));
            pq_64bit_free(&(s->d1->next_bitmap.max_seq_num));
            memset(&(s->d1->next_bitmap), 0x00, sizeof(DTLS1_BITMAP));
            pq_64bit_init(&(s->d1->next_bitmap.map));
            pq_64bit_init(&(s->d1->next_bitmap.max_seq_num));
            }
      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);
      }

#if PQ_64BIT_IS_INTEGER
static PQ_64BIT
bytes_to_long_long(unsigned char *bytes, PQ_64BIT *num)
       {
       PQ_64BIT _num;

       _num = (((PQ_64BIT)bytes[0]) << 56) |
               (((PQ_64BIT)bytes[1]) << 48) |
               (((PQ_64BIT)bytes[2]) << 40) |
               (((PQ_64BIT)bytes[3]) << 32) |
               (((PQ_64BIT)bytes[4]) << 24) |
               (((PQ_64BIT)bytes[5]) << 16) |
               (((PQ_64BIT)bytes[6]) <<  8) |
               (((PQ_64BIT)bytes[7])      );

         *num = _num ;
       return _num;
       }
#endif


static void
dtls1_clear_timeouts(SSL *s)
      {
      memset(&(s->d1->timeout), 0x00, sizeof(struct dtls1_timeout_st));
      }

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