d1_both.c

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/* ssl/d1_both.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 <limits.h>
#include <string.h>
#include <stdio.h>
#include "ssl_locl.h"
#include <openssl/buffer.h>
#include <openssl/rand.h>
#include <openssl/objects.h>
#include <openssl/evp.h>
#include <openssl/x509.h>

#define RSMBLY_BITMASK_SIZE(msg_len) (((msg_len) + 7) / 8)

#define RSMBLY_BITMASK_MARK(bitmask, start, end) { \
            if ((end) - (start) <= 8) { \
                long ii; \
                for (ii = (start); ii < (end); ii++) bitmask[((ii) >> 3)] |= (1 << ((ii) & 7)); \
            } else { \
                long ii; \
                bitmask[((start) >> 3)] |= bitmask_start_values[((start) & 7)]; \
                for (ii = (((start) >> 3) + 1); ii < ((((end) - 1)) >> 3); ii++) bitmask[ii] = 0xff; \
                bitmask[(((end) - 1) >> 3)] |= bitmask_end_values[((end) & 7)]; \
            } }

#define RSMBLY_BITMASK_IS_COMPLETE(bitmask, msg_len, is_complete) { \
            long ii; \
            OPENSSL_assert((msg_len) > 0); \
            is_complete = 1; \
            if (bitmask[(((msg_len) - 1) >> 3)] != bitmask_end_values[((msg_len) & 7)]) is_complete = 0; \
            if (is_complete) for (ii = (((msg_len) - 1) >> 3) - 1; ii >= 0 ; ii--) \
                if (bitmask[ii] != 0xff) { is_complete = 0; break; } }

#if 0
#define RSMBLY_BITMASK_PRINT(bitmask, msg_len) { \
            long ii; \
            printf("bitmask: "); for (ii = 0; ii < (msg_len); ii++) \
            printf("%d ", (bitmask[ii >> 3] & (1 << (ii & 7))) >> (ii & 7)); \
            printf("\n"); }
#endif

static unsigned char bitmask_start_values[] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80};
static unsigned char bitmask_end_values[]   = {0xff, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f};

/* XDTLS:  figure out the right values */
static unsigned int g_probable_mtu[] = {1500 - 28, 512 - 28, 256 - 28};

static unsigned int dtls1_guess_mtu(unsigned int curr_mtu);
static void dtls1_fix_message_header(SSL *s, unsigned long frag_off, 
    unsigned long frag_len);
static unsigned char *dtls1_write_message_header(SSL *s,
    unsigned char *p);
static void dtls1_set_message_header_int(SSL *s, unsigned char mt,
    unsigned long len, unsigned short seq_num, unsigned long frag_off, 
    unsigned long frag_len);
static long dtls1_get_message_fragment(SSL *s, int st1, int stn, 
    long max, int *ok);

static hm_fragment *
dtls1_hm_fragment_new(unsigned long frag_len, int reassembly)
    {
    hm_fragment *frag = NULL;
    unsigned char *buf = NULL;
    unsigned char *bitmask = NULL;

    frag = (hm_fragment *)OPENSSL_malloc(sizeof(hm_fragment));
    if ( frag == NULL)
        return NULL;

    if (frag_len)
        {
        buf = (unsigned char *)OPENSSL_malloc(frag_len);
        if ( buf == NULL)
            {
            OPENSSL_free(frag);
            return NULL;
            }
        }

    /* zero length fragment gets zero frag->fragment */
    frag->fragment = buf;

    /* Initialize reassembly bitmask if necessary */
    if (reassembly)
        {
        bitmask = (unsigned char *)OPENSSL_malloc(RSMBLY_BITMASK_SIZE(frag_len));
        if (bitmask == NULL)
            {
            if (buf != NULL) OPENSSL_free(buf);
            OPENSSL_free(frag);
            return NULL;
            }
        memset(bitmask, 0, RSMBLY_BITMASK_SIZE(frag_len));
        }

    frag->reassembly = bitmask;

    return frag;
    }

static void
dtls1_hm_fragment_free(hm_fragment *frag)
    {
    if (frag->fragment) OPENSSL_free(frag->fragment);
    if (frag->reassembly) OPENSSL_free(frag->reassembly);
    OPENSSL_free(frag);
    }

/* send s->init_buf in records of type 'type' (SSL3_RT_HANDSHAKE or SSL3_RT_CHANGE_CIPHER_SPEC) */
int dtls1_do_write(SSL *s, int type)
    {
    int ret;
    int curr_mtu;
    unsigned int len, frag_off, mac_size, blocksize;

    /* AHA!  Figure out the MTU, and stick to the right size */
    if (s->d1->mtu < dtls1_min_mtu() && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU))
        {
        s->d1->mtu = 
            BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);

        /* I've seen the kernel return bogus numbers when it doesn't know
         * (initial write), so just make sure we have a reasonable number */
        if (s->d1->mtu < dtls1_min_mtu())
            {
            s->d1->mtu = 0;
            s->d1->mtu = dtls1_guess_mtu(s->d1->mtu);
            BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU, 
                s->d1->mtu, NULL);
            }
        }
#if 0 
    mtu = s->d1->mtu;

    fprintf(stderr, "using MTU = %d\n", mtu);

    mtu -= (DTLS1_HM_HEADER_LENGTH + DTLS1_RT_HEADER_LENGTH);

    curr_mtu = mtu - BIO_wpending(SSL_get_wbio(s));

    if ( curr_mtu > 0)
        mtu = curr_mtu;
    else if ( ( ret = BIO_flush(SSL_get_wbio(s))) <= 0)
        return ret;

    if ( BIO_wpending(SSL_get_wbio(s)) + s->init_num >= mtu)
        {
        ret = BIO_flush(SSL_get_wbio(s));
        if ( ret <= 0)
            return ret;
        mtu = s->d1->mtu - (DTLS1_HM_HEADER_LENGTH + DTLS1_RT_HEADER_LENGTH);
        }
#endif

    OPENSSL_assert(s->d1->mtu >= dtls1_min_mtu());  /* should have something reasonable now */

    if ( s->init_off == 0  && type == SSL3_RT_HANDSHAKE)
        OPENSSL_assert(s->init_num == 
            (int)s->d1->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH);

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

    if (s->enc_write_ctx && 
        (EVP_CIPHER_mode( s->enc_write_ctx->cipher) & EVP_CIPH_CBC_MODE))
        blocksize = 2 * EVP_CIPHER_block_size(s->enc_write_ctx->cipher);
    else
        blocksize = 0;

    frag_off = 0;
    while( s->init_num)
        {
        curr_mtu = s->d1->mtu - BIO_wpending(SSL_get_wbio(s)) - 
            DTLS1_RT_HEADER_LENGTH - mac_size - blocksize;

        if ( curr_mtu <= DTLS1_HM_HEADER_LENGTH)
            {
            /* grr.. we could get an error if MTU picked was wrong */
            ret = BIO_flush(SSL_get_wbio(s));
            if ( ret <= 0)
                return ret;
            curr_mtu = s->d1->mtu - DTLS1_RT_HEADER_LENGTH -
                mac_size - blocksize;
            }

        if ( s->init_num > curr_mtu)
            len = curr_mtu;
        else
            len = s->init_num;


        /* XDTLS: this function is too long.  split out the CCS part */
        if ( type == SSL3_RT_HANDSHAKE)
            {
            if ( s->init_off != 0)
                {
                OPENSSL_assert(s->init_off > DTLS1_HM_HEADER_LENGTH);
                s->init_off -= DTLS1_HM_HEADER_LENGTH;
                s->init_num += DTLS1_HM_HEADER_LENGTH;

                /* write atleast DTLS1_HM_HEADER_LENGTH bytes */
                if ( len <= DTLS1_HM_HEADER_LENGTH)  
                    len += DTLS1_HM_HEADER_LENGTH;
                }

            dtls1_fix_message_header(s, frag_off, 
                len - DTLS1_HM_HEADER_LENGTH);

            dtls1_write_message_header(s, (unsigned char *)&s->init_buf->data[s->init_off]);

            OPENSSL_assert(len >= DTLS1_HM_HEADER_LENGTH);
            }

        ret=dtls1_write_bytes(s,type,&s->init_buf->data[s->init_off],
            len);
        if (ret < 0)
            {
            /* might need to update MTU here, but we don't know
             * which previous packet caused the failure -- so can't
             * really retransmit anything.  continue as if everything
             * is fine and wait for an alert to handle the
             * retransmit 
             */
            if ( BIO_ctrl(SSL_get_wbio(s),
                BIO_CTRL_DGRAM_MTU_EXCEEDED, 0, NULL) > 0 )
                s->d1->mtu = BIO_ctrl(SSL_get_wbio(s),
                    BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
            else
                return(-1);
            }
        else
            {

            /* bad if this assert fails, only part of the handshake
             * message got sent.  but why would this happen? */
            OPENSSL_assert(len == (unsigned int)ret);

            if (type == SSL3_RT_HANDSHAKE && ! s->d1->retransmitting)
                {
                /* should not be done for 'Hello Request's, but in that case
                 * we'll ignore the result anyway */
                unsigned char *p = (unsigned char *)&s->init_buf->data[s->init_off];
                const struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
                int xlen;

                if (frag_off == 0 && s->version != DTLS1_BAD_VER)
                    {
                    /* reconstruct message header is if it
                     * is being sent in single fragment */
                    *p++ = msg_hdr->type;
                    l2n3(msg_hdr->msg_len,p);
                    s2n (msg_hdr->seq,p);
                    l2n3(0,p);
                    l2n3(msg_hdr->msg_len,p);
                    p  -= DTLS1_HM_HEADER_LENGTH;
                    xlen = ret;
                    }
                else
                    {
                    p  += DTLS1_HM_HEADER_LENGTH;
                    xlen = ret - DTLS1_HM_HEADER_LENGTH;
                    }

                ssl3_finish_mac(s, p, xlen);
                }

            if (ret == s->init_num)
                {
                if (s->msg_callback)
                    s->msg_callback(1, s->version, type, s->init_buf->data, 
                        (size_t)(s->init_off + s->init_num), s, 
                        s->msg_callback_arg);

                s->init_off = 0;  /* done writing this message */
                s->init_num = 0;

                return(1);
                }
            s->init_off+=ret;
            s->init_num-=ret;
            frag_off += (ret -= DTLS1_HM_HEADER_LENGTH);
            }
        }
    return(0);
    }


/* Obtain handshake message of message type 'mt' (any if mt == -1),
 * maximum acceptable body length 'max'.
 * Read an entire handshake message.  Handshake messages arrive in
 * fragments.
 */
long dtls1_get_message(SSL *s, int st1, int stn, int mt, long max, int *ok)
    {
    int i, al;
    struct hm_header_st *msg_hdr;
    unsigned char *p;
    unsigned long msg_len;

    /* s3->tmp is used to store messages that are unexpected, caused
     * by the absence of an optional handshake message */
    if (s->s3->tmp.reuse_message)
        {
        s->s3->tmp.reuse_message=0;
        if ((mt >= 0) && (s->s3->tmp.message_type != mt))
            {
            al=SSL_AD_UNEXPECTED_MESSAGE;
            SSLerr(SSL_F_DTLS1_GET_MESSAGE,SSL_R_UNEXPECTED_MESSAGE);
            goto f_err;
            }
        *ok=1;
        s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
        s->init_num = (int)s->s3->tmp.message_size;
        return s->init_num;
        }

    msg_hdr = &s->d1->r_msg_hdr;
    memset(msg_hdr, 0x00, sizeof(struct hm_header_st));

again:
    i = dtls1_get_message_fragment(s, st1, stn, max, ok);
    if ( i == DTLS1_HM_BAD_FRAGMENT ||
        i == DTLS1_HM_FRAGMENT_RETRY)  /* bad fragment received */
        goto again;
    else if ( i <= 0 && !*ok)
        return i;

    p = (unsigned char *)s->init_buf->data;
    msg_len = msg_hdr->msg_len;

    /* reconstruct message header */
    *(p++) = msg_hdr->type;
    l2n3(msg_len,p);
    s2n (msg_hdr->seq,p);
    l2n3(0,p);
    l2n3(msg_len,p);
    if (s->version != DTLS1_BAD_VER) {
        p       -= DTLS1_HM_HEADER_LENGTH;
        msg_len += DTLS1_HM_HEADER_LENGTH;
    }

    ssl3_finish_mac(s, p, msg_len);
    if (s->msg_callback)
        s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
            p, msg_len,
            s, s->msg_callback_arg);

    memset(msg_hdr, 0x00, sizeof(struct hm_header_st));

    /* Don't change sequence numbers while listening */
    if (!s->d1->listen)
        s->d1->handshake_read_seq++;

    s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
    return s->init_num;

f_err:
    ssl3_send_alert(s,SSL3_AL_FATAL,al);
    *ok = 0;
    return -1;
    }


static int dtls1_preprocess_fragment(SSL *s,struct hm_header_st *msg_hdr,int max)
    {
    size_t frag_off,frag_len,msg_len;

    msg_len  = msg_hdr->msg_len;
    frag_off = msg_hdr->frag_off;
    frag_len = msg_hdr->frag_len;

    /* sanity checking */
    if ( (frag_off+frag_len) > msg_len)
        {
        SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
        return SSL_AD_ILLEGAL_PARAMETER;
        }

    if ( (frag_off+frag_len) > (unsigned long)max)
        {
        SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
        return SSL_AD_ILLEGAL_PARAMETER;
        }

    if ( s->d1->r_msg_hdr.frag_off == 0) /* first fragment */
        {
        /* msg_len is limited to 2^24, but is effectively checked
         * against max above */
        if (!BUF_MEM_grow_clean(s->init_buf,msg_len+DTLS1_HM_HEADER_LENGTH))
            {
            SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,ERR_R_BUF_LIB);
            return SSL_AD_INTERNAL_ERROR;
            }

        s->s3->tmp.message_size  = msg_len;
        s->d1->r_msg_hdr.msg_len = msg_len;
        s->s3->tmp.message_type  = msg_hdr->type;
        s->d1->r_msg_hdr.type    = msg_hdr->type;
        s->d1->r_msg_hdr.seq     = msg_hdr->seq;
        }
    else if (msg_len != s->d1->r_msg_hdr.msg_len)
        {
        /* They must be playing with us! BTW, failure to enforce
         * upper limit would open possibility for buffer overrun. */
        SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
        return SSL_AD_ILLEGAL_PARAMETER;
        }

    return 0; /* no error */
    }


static int
dtls1_retrieve_buffered_fragment(SSL *s, long max, int *ok)
    {
    /* (0) check whether the desired fragment is available
     * if so:
     * (1) copy over the fragment to s->init_buf->data[]
     * (2) update s->init_num
     */
    pitem *item;
    hm_fragment *frag;
    int al;

    *ok = 0;
    item = pqueue_peek(s->d1->buffered_messages);
    if ( item == NULL)
        return 0;

    frag = (hm_fragment *)item->data;
    
    /* Don't return if reassembly still in progress */
    if (frag->reassembly != NULL)
        return 0;

    if ( s->d1->handshake_read_seq == frag->msg_header.seq)
        {
        unsigned long frag_len = frag->msg_header.frag_len;
        pqueue_pop(s->d1->buffered_messages);

        al=dtls1_preprocess_fragment(s,&frag->msg_header,max);

        if (al==0) /* no alert */
            {
            unsigned char *p = (unsigned char *)s->init_buf->data+DTLS1_HM_HEADER_LENGTH;
            memcpy(&p[frag->msg_header.frag_off],
                frag->fragment,frag->msg_header.frag_len);
            }

        dtls1_hm_fragment_free(frag);
        pitem_free(item);

        if (al==0)
            {
            *ok = 1;
            return frag_len;
            }

        ssl3_send_alert(s,SSL3_AL_FATAL,al);
        s->init_num = 0;
        *ok = 0;
        return -1;
        }
    else
        return 0;
    }


static int
dtls1_reassemble_fragment(SSL *s, struct hm_header_st* msg_hdr, int *ok)
    {
    hm_fragment *frag = NULL;
    pitem *item = NULL;
    int i = -1, is_complete;
    unsigned char seq64be[8];
    unsigned long frag_len = msg_hdr->frag_len, max_len;

    if ((msg_hdr->frag_off+frag_len) > msg_hdr->msg_len)
        goto err;

    /* Determine maximum allowed message size. Depends on (user set)
     * maximum certificate length, but 16k is minimum.
     */
    if (DTLS1_HM_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH < s->max_cert_list)
        max_len = s->max_cert_list;
    else
        max_len = DTLS1_HM_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH;

    if ((msg_hdr->frag_off+frag_len) > max_len)
        goto err;

    /* Try to find item in queue */
    memset(seq64be,0,sizeof(seq64be));
    seq64be[6] = (unsigned char) (msg_hdr->seq>>8);
    seq64be[7] = (unsigned char) msg_hdr->seq;
    item = pqueue_find(s->d1->buffered_messages, seq64be);

    if (item == NULL)
        {
        frag = dtls1_hm_fragment_new(msg_hdr->msg_len, 1);
        if ( frag == NULL)
            goto err;
        memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));
        frag->msg_header.frag_len = frag->msg_header.msg_len;
        frag->msg_header.frag_off = 0;
        }
    else
        frag = (hm_fragment*) item->data;

    /* If message is already reassembled, this must be a
     * retransmit and can be dropped.
     */
    if (frag->reassembly == NULL)
        {
        unsigned char devnull [256];

        while (frag_len)
            {
            i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
                devnull,
                frag_len>sizeof(devnull)?sizeof(devnull):frag_len,0);
            if (i<=0) goto err;
            frag_len -= i;
            }
        return DTLS1_HM_FRAGMENT_RETRY;
        }

    /* read the body of the fragment (header has already been read */
    i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
        frag->fragment + msg_hdr->frag_off,frag_len,0);
    if (i<=0 || (unsigned long)i!=frag_len)
        goto err;

    RSMBLY_BITMASK_MARK(frag->reassembly, (long)msg_hdr->frag_off,
                        (long)(msg_hdr->frag_off + frag_len));

    RSMBLY_BITMASK_IS_COMPLETE(frag->reassembly, (long)msg_hdr->msg_len,
                               is_complete);

    if (is_complete)
        {
        OPENSSL_free(frag->reassembly);
        frag->reassembly = NULL;
        }

    if (item == NULL)
        {
        memset(seq64be,0,sizeof(seq64be));
        seq64be[6] = (unsigned char)(msg_hdr->seq>>8);
        seq64be[7] = (unsigned char)(msg_hdr->seq);

        item = pitem_new(seq64be, frag);
        if (item == NULL)
            {
            goto err;
            i = -1;
            }

        pqueue_insert(s->d1->buffered_messages, item);
        }

    return DTLS1_HM_FRAGMENT_RETRY;

err:
    if (frag != NULL) dtls1_hm_fragment_free(frag);
    if (item != NULL) OPENSSL_free(item);
    *ok = 0;
    return i;
    }


static int
dtls1_process_out_of_seq_message(SSL *s, struct hm_header_st* msg_hdr, int *ok)
{
    int i=-1;
    hm_fragment *frag = NULL;
    pitem *item = NULL;
    unsigned char seq64be[8];
    unsigned long frag_len = msg_hdr->frag_len;

    if ((msg_hdr->frag_off+frag_len) > msg_hdr->msg_len)
        goto err;

    /* Try to find item in queue, to prevent duplicate entries */
    memset(seq64be,0,sizeof(seq64be));
    seq64be[6] = (unsigned char) (msg_hdr->seq>>8);
    seq64be[7] = (unsigned char) msg_hdr->seq;
    item = pqueue_find(s->d1->buffered_messages, seq64be);

    /* If we already have an entry and this one is a fragment,
     * don't discard it and rather try to reassemble it.
     */
    if (item != NULL && frag_len < msg_hdr->msg_len)
        item = NULL;

    /* Discard the message if sequence number was already there, is
     * too far in the future, already in the queue or if we received
     * a FINISHED before the SERVER_HELLO, which then must be a stale
     * retransmit.
     */
    if (msg_hdr->seq <= s->d1->handshake_read_seq ||
        msg_hdr->seq > s->d1->handshake_read_seq + 10 || item != NULL ||
        (s->d1->handshake_read_seq == 0 && msg_hdr->type == SSL3_MT_FINISHED))
        {
        unsigned char devnull [256];

        while (frag_len)
            {
            i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
                devnull,
                frag_len>sizeof(devnull)?sizeof(devnull):frag_len,0);
            if (i<=0) goto err;
            frag_len -= i;
            }
        }
    else
        {
        if (frag_len && frag_len < msg_hdr->msg_len)
            return dtls1_reassemble_fragment(s, msg_hdr, ok);

        frag = dtls1_hm_fragment_new(frag_len, 0);
        if ( frag == NULL)
            goto err;

        memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));

        if (frag_len)
            {
            /* read the body of the fragment (header has already been read */
            i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
                frag->fragment,frag_len,0);
            if (i<=0 || (unsigned long)i!=frag_len)
                goto err;
            }

        memset(seq64be,0,sizeof(seq64be));
        seq64be[6] = (unsigned char)(msg_hdr->seq>>8);
        seq64be[7] = (unsigned char)(msg_hdr->seq);

        item = pitem_new(seq64be, frag);
        if ( item == NULL)
            goto err;

        pqueue_insert(s->d1->buffered_messages, item);
        }

    return DTLS1_HM_FRAGMENT_RETRY;

err:
    if ( frag != NULL) dtls1_hm_fragment_free(frag);
    if ( item != NULL) OPENSSL_free(item);
    *ok = 0;
    return i;
    }


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

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

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

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

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

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

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

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

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

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

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

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

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

    *ok = 1;

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

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

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

int dtls1_send_finished(SSL *s, int a, int b, const char *sender, int slen)
    {
    unsigned char *p,*d;
    int i;
    unsigned long l;

    if (s->state == a)
        {
        d=(unsigned char *)s->init_buf->data;
        p= &(d[DTLS1_HM_HEADER_LENGTH]);

        i=s->method->ssl3_enc->final_finish_mac(s,
            sender,slen,s->s3->tmp.finish_md);
        s->s3->tmp.finish_md_len = i;
        memcpy(p, s->s3->tmp.finish_md, i);
        p+=i;
        l=i;

    /* Copy the finished so we can use it for
     * renegotiation checks
     */
    if(s->type == SSL_ST_CONNECT)
        {
        OPENSSL_assert(i <= EVP_MAX_MD_SIZE);
        memcpy(s->s3->previous_client_finished, 
               s->s3->tmp.finish_md, i);
        s->s3->previous_client_finished_len=i;
        }
    else
        {
        OPENSSL_assert(i <= EVP_MAX_MD_SIZE);
        memcpy(s->s3->previous_server_finished, 
               s->s3->tmp.finish_md, i);
        s->s3->previous_server_finished_len=i;
        }

#ifdef OPENSSL_SYS_WIN16
        /* MSVC 1.5 does not clear the top bytes of the word unless
         * I do this.
         */
        l&=0xffff;
#endif

        d = dtls1_set_message_header(s, d, SSL3_MT_FINISHED, l, 0, l);
        s->init_num=(int)l+DTLS1_HM_HEADER_LENGTH;
        s->init_off=0;

        /* buffer the message to handle re-xmits */
        dtls1_buffer_message(s, 0);

        s->state=b;
        }

    /* SSL3_ST_SEND_xxxxxx_HELLO_B */
    return(dtls1_do_write(s,SSL3_RT_HANDSHAKE));
    }

/* for these 2 messages, we need to
 * ssl->enc_read_ctx            re-init
 * ssl->s3->read_sequence       zero
 * ssl->s3->read_mac_secret     re-init
 * ssl->session->read_sym_enc       assign
 * ssl->session->read_compression   assign
 * ssl->session->read_hash      assign
 */
int dtls1_send_change_cipher_spec(SSL *s, int a, int b)
    { 
    unsigned char *p;

    if (s->state == a)
        {
        p=(unsigned char *)s->init_buf->data;
        *p++=SSL3_MT_CCS;
        s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
        s->init_num=DTLS1_CCS_HEADER_LENGTH;

        if (s->version == DTLS1_BAD_VER) {
            s->d1->next_handshake_write_seq++;
            s2n(s->d1->handshake_write_seq,p);
            s->init_num+=2;
        }

        s->init_off=0;

        dtls1_set_message_header_int(s, SSL3_MT_CCS, 0, 
            s->d1->handshake_write_seq, 0, 0);

        /* buffer the message to handle re-xmits */
        dtls1_buffer_message(s, 1);

        s->state=b;
        }

    /* SSL3_ST_CW_CHANGE_B */
    return(dtls1_do_write(s,SSL3_RT_CHANGE_CIPHER_SPEC));
    }

static int dtls1_add_cert_to_buf(BUF_MEM *buf, unsigned long *l, X509 *x)
    {
    int n;
    unsigned char *p;

    n=i2d_X509(x,NULL);
    if (!BUF_MEM_grow_clean(buf,(int)(n+(*l)+3)))
        {
        SSLerr(SSL_F_DTLS1_ADD_CERT_TO_BUF,ERR_R_BUF_LIB);
        return 0;
        }
    p=(unsigned char *)&(buf->data[*l]);
    l2n3(n,p);
    i2d_X509(x,&p);
    *l+=n+3;

    return 1;
    }
unsigned long dtls1_output_cert_chain(SSL *s, X509 *x)
    {
    unsigned char *p;
    int i;
    unsigned long l= 3 + DTLS1_HM_HEADER_LENGTH;
    BUF_MEM *buf;

    /* TLSv1 sends a chain with nothing in it, instead of an alert */
    buf=s->init_buf;
    if (!BUF_MEM_grow_clean(buf,10))
        {
        SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_BUF_LIB);
        return(0);
        }
    if (x != NULL)
        {
        X509_STORE_CTX xs_ctx;

        if (!X509_STORE_CTX_init(&xs_ctx,s->ctx->cert_store,x,NULL))
            {
            SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_X509_LIB);
            return(0);
            }
  
        X509_verify_cert(&xs_ctx);
        /* Don't leave errors in the queue */
        ERR_clear_error();
        for (i=0; i < sk_X509_num(xs_ctx.chain); i++)
            {
            x = sk_X509_value(xs_ctx.chain, i);

            if (!dtls1_add_cert_to_buf(buf, &l, x))
                {
                X509_STORE_CTX_cleanup(&xs_ctx);
                return 0;
                }
            }
        X509_STORE_CTX_cleanup(&xs_ctx);
        }
    /* Thawte special :-) */
    for (i=0; i<sk_X509_num(s->ctx->extra_certs); i++)
        {
        x=sk_X509_value(s->ctx->extra_certs,i);
        if (!dtls1_add_cert_to_buf(buf, &l, x))
            return 0;
        }

    l-= (3 + DTLS1_HM_HEADER_LENGTH);

    p=(unsigned char *)&(buf->data[DTLS1_HM_HEADER_LENGTH]);
    l2n3(l,p);
    l+=3;
    p=(unsigned char *)&(buf->data[0]);
    p = dtls1_set_message_header(s, p, SSL3_MT_CERTIFICATE, l, 0, l);

    l+=DTLS1_HM_HEADER_LENGTH;
    return(l);
    }

int dtls1_read_failed(SSL *s, int code)
    {
    if ( code > 0)
        {
        fprintf( stderr, "invalid state reached %s:%d", __FILE__, __LINE__);
        return 1;
        }

    if (!dtls1_is_timer_expired(s))
        {
        /* not a timeout, none of our business, 
           let higher layers handle this.  in fact it's probably an error */
        return code;
        }

#ifndef OPENSSL_NO_HEARTBEATS
    if (!SSL_in_init(s) && !s->tlsext_hb_pending)  /* done, no need to send a retransmit */
#else
    if (!SSL_in_init(s))  /* done, no need to send a retransmit */
#endif
        {
        BIO_set_flags(SSL_get_rbio(s), BIO_FLAGS_READ);
        return code;
        }

#if 0 /* for now, each alert contains only one record number */
    item = pqueue_peek(state->rcvd_records);
    if ( item )
        {
        /* send an alert immediately for all the missing records */
        }
    else
#endif

#if 0  /* no more alert sending, just retransmit the last set of messages */
    if ( state->timeout.read_timeouts >= DTLS1_TMO_READ_COUNT)
        ssl3_send_alert(s,SSL3_AL_WARNING,
            DTLS1_AD_MISSING_HANDSHAKE_MESSAGE);
#endif

    return dtls1_handle_timeout(s);
    }

int
dtls1_get_queue_priority(unsigned short seq, int is_ccs)
    {
    /* The index of the retransmission queue actually is the message sequence number,
     * since the queue only contains messages of a single handshake. However, the
     * ChangeCipherSpec has no message sequence number and so using only the sequence
     * will result in the CCS and Finished having the same index. To prevent this,
     * the sequence number is multiplied by 2. In case of a CCS 1 is subtracted.
     * This does not only differ CSS and Finished, it also maintains the order of the
     * index (important for priority queues) and fits in the unsigned short variable.
     */ 
    return seq * 2 - is_ccs;
    }

int
dtls1_retransmit_buffered_messages(SSL *s)
    {
    pqueue sent = s->d1->sent_messages;
    piterator iter;
    pitem *item;
    hm_fragment *frag;
    int found = 0;

    iter = pqueue_iterator(sent);

    for ( item = pqueue_next(&iter); item != NULL; item = pqueue_next(&iter))
        {
        frag = (hm_fragment *)item->data;
            if ( dtls1_retransmit_message(s,
                (unsigned short)dtls1_get_queue_priority(frag->msg_header.seq, frag->msg_header.is_ccs),
                0, &found) <= 0 && found)
            {
            fprintf(stderr, "dtls1_retransmit_message() failed\n");
            return -1;
            }
        }

    return 1;
    }

int
dtls1_buffer_message(SSL *s, int is_ccs)
    {
    pitem *item;
    hm_fragment *frag;
    unsigned char seq64be[8];

    /* this function is called immediately after a message has 
     * been serialized */
    OPENSSL_assert(s->init_off == 0);

    frag = dtls1_hm_fragment_new(s->init_num, 0);

    memcpy(frag->fragment, s->init_buf->data, s->init_num);

    if ( is_ccs)
        {
        OPENSSL_assert(s->d1->w_msg_hdr.msg_len + 
                   ((s->version==DTLS1_VERSION)?DTLS1_CCS_HEADER_LENGTH:3) == (unsigned int)s->init_num);
        }
    else
        {
        OPENSSL_assert(s->d1->w_msg_hdr.msg_len + 
            DTLS1_HM_HEADER_LENGTH == (unsigned int)s->init_num);
        }

    frag->msg_header.msg_len = s->d1->w_msg_hdr.msg_len;
    frag->msg_header.seq = s->d1->w_msg_hdr.seq;
    frag->msg_header.type = s->d1->w_msg_hdr.type;
    frag->msg_header.frag_off = 0;
    frag->msg_header.frag_len = s->d1->w_msg_hdr.msg_len;
    frag->msg_header.is_ccs = is_ccs;

    /* save current state*/
    frag->msg_header.saved_retransmit_state.enc_write_ctx = s->enc_write_ctx;
    frag->msg_header.saved_retransmit_state.write_hash = s->write_hash;
    frag->msg_header.saved_retransmit_state.compress = s->compress;
    frag->msg_header.saved_retransmit_state.session = s->session;
    frag->msg_header.saved_retransmit_state.epoch = s->d1->w_epoch;
    
    memset(seq64be,0,sizeof(seq64be));
    seq64be[6] = (unsigned char)(dtls1_get_queue_priority(frag->msg_header.seq,
                                                          frag->msg_header.is_ccs)>>8);
    seq64be[7] = (unsigned char)(dtls1_get_queue_priority(frag->msg_header.seq,
                                                          frag->msg_header.is_ccs));

    item = pitem_new(seq64be, frag);
    if ( item == NULL)
        {
        dtls1_hm_fragment_free(frag);
        return 0;
        }

#if 0
    fprintf( stderr, "buffered messge: \ttype = %xx\n", msg_buf->type);
    fprintf( stderr, "\t\t\t\t\tlen = %d\n", msg_buf->len);
    fprintf( stderr, "\t\t\t\t\tseq_num = %d\n", msg_buf->seq_num);
#endif

    pqueue_insert(s->d1->sent_messages, item);
    return 1;
    }

int
dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
    int *found)
    {
    int ret;
    /* XDTLS: for now assuming that read/writes are blocking */
    pitem *item;
    hm_fragment *frag ;
    unsigned long header_length;
    unsigned char seq64be[8];
    struct dtls1_retransmit_state saved_state;
    unsigned char save_write_sequence[8];

    /*
      OPENSSL_assert(s->init_num == 0);
      OPENSSL_assert(s->init_off == 0);
     */

    /* XDTLS:  the requested message ought to be found, otherwise error */
    memset(seq64be,0,sizeof(seq64be));
    seq64be[6] = (unsigned char)(seq>>8);
    seq64be[7] = (unsigned char)seq;

    item = pqueue_find(s->d1->sent_messages, seq64be);
    if ( item == NULL)
        {
        fprintf(stderr, "retransmit:  message %d non-existant\n", seq);
        *found = 0;
        return 0;
        }

    *found = 1;
    frag = (hm_fragment *)item->data;

    if ( frag->msg_header.is_ccs)
        header_length = DTLS1_CCS_HEADER_LENGTH;
    else
        header_length = DTLS1_HM_HEADER_LENGTH;

    memcpy(s->init_buf->data, frag->fragment, 
        frag->msg_header.msg_len + header_length);
        s->init_num = frag->msg_header.msg_len + header_length;

    dtls1_set_message_header_int(s, frag->msg_header.type, 
        frag->msg_header.msg_len, frag->msg_header.seq, 0, 
        frag->msg_header.frag_len);

    /* save current state */
    saved_state.enc_write_ctx = s->enc_write_ctx;
    saved_state.write_hash = s->write_hash;
    saved_state.compress = s->compress;
    saved_state.session = s->session;
    saved_state.epoch = s->d1->w_epoch;
    saved_state.epoch = s->d1->w_epoch;
    
    s->d1->retransmitting = 1;
    
    /* restore state in which the message was originally sent */
    s->enc_write_ctx = frag->msg_header.saved_retransmit_state.enc_write_ctx;
    s->write_hash = frag->msg_header.saved_retransmit_state.write_hash;
    s->compress = frag->msg_header.saved_retransmit_state.compress;
    s->session = frag->msg_header.saved_retransmit_state.session;
    s->d1->w_epoch = frag->msg_header.saved_retransmit_state.epoch;
    
    if (frag->msg_header.saved_retransmit_state.epoch == saved_state.epoch - 1)
    {
        memcpy(save_write_sequence, s->s3->write_sequence, sizeof(s->s3->write_sequence));
        memcpy(s->s3->write_sequence, s->d1->last_write_sequence, sizeof(s->s3->write_sequence));
    }
    
    ret = dtls1_do_write(s, frag->msg_header.is_ccs ? 
                         SSL3_RT_CHANGE_CIPHER_SPEC : SSL3_RT_HANDSHAKE);
    
    /* restore current state */
    s->enc_write_ctx = saved_state.enc_write_ctx;
    s->write_hash = saved_state.write_hash;
    s->compress = saved_state.compress;
    s->session = saved_state.session;
    s->d1->w_epoch = saved_state.epoch;
    
    if (frag->msg_header.saved_retransmit_state.epoch == saved_state.epoch - 1)
    {
        memcpy(s->d1->last_write_sequence, s->s3->write_sequence, sizeof(s->s3->write_sequence));
        memcpy(s->s3->write_sequence, save_write_sequence, sizeof(s->s3->write_sequence));
    }

    s->d1->retransmitting = 0;

    (void)BIO_flush(SSL_get_wbio(s));
    return ret;
    }

/* call this function when the buffered messages are no longer needed */
void
dtls1_clear_record_buffer(SSL *s)
    {
    pitem *item;

    for(item = pqueue_pop(s->d1->sent_messages);
        item != NULL; item = pqueue_pop(s->d1->sent_messages))
        {
        dtls1_hm_fragment_free((hm_fragment *)item->data);
        pitem_free(item);
        }
    }


unsigned char *
dtls1_set_message_header(SSL *s, unsigned char *p, unsigned char mt,
            unsigned long len, unsigned long frag_off, unsigned long frag_len)
    {
    /* Don't change sequence numbers while listening */
    if (frag_off == 0 && !s->d1->listen)
        {
        s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
        s->d1->next_handshake_write_seq++;
        }

    dtls1_set_message_header_int(s, mt, len, s->d1->handshake_write_seq,
        frag_off, frag_len);

    return p += DTLS1_HM_HEADER_LENGTH;
    }


/* don't actually do the writing, wait till the MTU has been retrieved */
static void
dtls1_set_message_header_int(SSL *s, unsigned char mt,
                unsigned long len, unsigned short seq_num, unsigned long frag_off,
                unsigned long frag_len)
    {
    struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;

    msg_hdr->type = mt;
    msg_hdr->msg_len = len;
    msg_hdr->seq = seq_num;
    msg_hdr->frag_off = frag_off;
    msg_hdr->frag_len = frag_len;
    }

static void
dtls1_fix_message_header(SSL *s, unsigned long frag_off,
            unsigned long frag_len)
    {
    struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;

    msg_hdr->frag_off = frag_off;
    msg_hdr->frag_len = frag_len;
    }

static unsigned char *
dtls1_write_message_header(SSL *s, unsigned char *p)
    {
    struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;

    *p++ = msg_hdr->type;
    l2n3(msg_hdr->msg_len, p);

    s2n(msg_hdr->seq, p);
    l2n3(msg_hdr->frag_off, p);
    l2n3(msg_hdr->frag_len, p);

    return p;
    }

unsigned int 
dtls1_min_mtu(void)
    {
    return (g_probable_mtu[(sizeof(g_probable_mtu) / 
        sizeof(g_probable_mtu[0])) - 1]);
    }

static unsigned int 
dtls1_guess_mtu(unsigned int curr_mtu)
    {
    unsigned int i;

    if ( curr_mtu == 0 )
        return g_probable_mtu[0] ;

    for ( i = 0; i < sizeof(g_probable_mtu)/sizeof(g_probable_mtu[0]); i++)
        if ( curr_mtu > g_probable_mtu[i])
            return g_probable_mtu[i];

    return curr_mtu;
    }

void
dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
    {
    memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
    msg_hdr->type = *(data++);
    n2l3(data, msg_hdr->msg_len);

    n2s(data, msg_hdr->seq);
    n2l3(data, msg_hdr->frag_off);
    n2l3(data, msg_hdr->frag_len);
    }

void
dtls1_get_ccs_header(unsigned char *data, struct ccs_header_st *ccs_hdr)
    {
    memset(ccs_hdr, 0x00, sizeof(struct ccs_header_st));

    ccs_hdr->type = *(data++);
    }

int dtls1_shutdown(SSL *s)
    {
    int ret;
#ifndef OPENSSL_NO_SCTP
    if (BIO_dgram_is_sctp(SSL_get_wbio(s)) &&
        !(s->shutdown & SSL_SENT_SHUTDOWN))
        {
        ret = BIO_dgram_sctp_wait_for_dry(SSL_get_wbio(s));
        if (ret < 0) return -1;

        if (ret == 0)
            BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1, NULL);
        }
#endif
    ret = ssl3_shutdown(s);
#ifndef OPENSSL_NO_SCTP
    BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL);
#endif
    return ret;
    }

#ifndef OPENSSL_NO_HEARTBEATS
int
dtls1_process_heartbeat(SSL *s)
    {
    unsigned char *p = &s->s3->rrec.data[0], *pl;
    unsigned short hbtype;
    unsigned int payload;
    unsigned int padding = 16; /* Use minimum padding */

    /* Read type and payload length first */
    hbtype = *p++;
    n2s(p, payload);
    pl = p;

    if (s->msg_callback)
        s->msg_callback(0, s->version, TLS1_RT_HEARTBEAT,
            &s->s3->rrec.data[0], s->s3->rrec.length,
            s, s->msg_callback_arg);

    if (hbtype == TLS1_HB_REQUEST)
        {
        unsigned char *buffer, *bp;
        int r;

        /* Allocate memory for the response, size is 1 byte
         * message type, plus 2 bytes payload length, plus
         * payload, plus padding
         */
        buffer = OPENSSL_malloc(1 + 2 + payload + padding);
        bp = buffer;

        /* Enter response type, length and copy payload */
        *bp++ = TLS1_HB_RESPONSE;
        s2n(payload, bp);
        memcpy(bp, pl, payload);
        bp += payload;
        /* Random padding */
        RAND_pseudo_bytes(bp, padding);

        r = dtls1_write_bytes(s, TLS1_RT_HEARTBEAT, buffer, 3 + payload + padding);

        if (r >= 0 && s->msg_callback)
            s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
                buffer, 3 + payload + padding,
                s, s->msg_callback_arg);

        OPENSSL_free(buffer);

        if (r < 0)
            return r;
        }
    else if (hbtype == TLS1_HB_RESPONSE)
        {
        unsigned int seq;

        /* We only send sequence numbers (2 bytes unsigned int),
         * and 16 random bytes, so we just try to read the
         * sequence number */
        n2s(pl, seq);

        if (payload == 18 && seq == s->tlsext_hb_seq)
            {
            dtls1_stop_timer(s);
            s->tlsext_hb_seq++;
            s->tlsext_hb_pending = 0;
            }
        }

    return 0;
    }

int
dtls1_heartbeat(SSL *s)
    {
    unsigned char *buf, *p;
    int ret;
    unsigned int payload = 18; /* Sequence number + random bytes */
    unsigned int padding = 16; /* Use minimum padding */

    /* Only send if peer supports and accepts HB requests... */
    if (!(s->tlsext_heartbeat & SSL_TLSEXT_HB_ENABLED) ||
        s->tlsext_heartbeat & SSL_TLSEXT_HB_DONT_SEND_REQUESTS)
        {
        SSLerr(SSL_F_DTLS1_HEARTBEAT,SSL_R_TLS_HEARTBEAT_PEER_DOESNT_ACCEPT);
        return -1;
        }

    /* ...and there is none in flight yet... */
    if (s->tlsext_hb_pending)
        {
        SSLerr(SSL_F_DTLS1_HEARTBEAT,SSL_R_TLS_HEARTBEAT_PENDING);
        return -1;
        }

    /* ...and no handshake in progress. */
    if (SSL_in_init(s) || s->in_handshake)
        {
        SSLerr(SSL_F_DTLS1_HEARTBEAT,SSL_R_UNEXPECTED_MESSAGE);
        return -1;
        }

    /* Check if padding is too long, payload and padding
     * must not exceed 2^14 - 3 = 16381 bytes in total.
     */
    OPENSSL_assert(payload + padding <= 16381);

    /* Create HeartBeat message, we just use a sequence number
     * as payload to distuingish different messages and add
     * some random stuff.
     *  - Message Type, 1 byte
     *  - Payload Length, 2 bytes (unsigned int)
     *  - Payload, the sequence number (2 bytes uint)
     *  - Payload, random bytes (16 bytes uint)
     *  - Padding
     */
    buf = OPENSSL_malloc(1 + 2 + payload + padding);
    p = buf;
    /* Message Type */
    *p++ = TLS1_HB_REQUEST;
    /* Payload length (18 bytes here) */
    s2n(payload, p);
    /* Sequence number */
    s2n(s->tlsext_hb_seq, p);
    /* 16 random bytes */
    RAND_pseudo_bytes(p, 16);
    p += 16;
    /* Random padding */
    RAND_pseudo_bytes(p, padding);

    ret = dtls1_write_bytes(s, TLS1_RT_HEARTBEAT, buf, 3 + payload + padding);
    if (ret >= 0)
        {
        if (s->msg_callback)
            s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
                buf, 3 + payload + padding,
                s, s->msg_callback_arg);

        dtls1_start_timer(s);
        s->tlsext_hb_pending = 1;
        }

    OPENSSL_free(buf);

    return ret;
    }
#endif