Merge commit 'dfc115332c94a2f62058ac7f2bce7631fbd20b3d'

[unleashed/tickless.git] / lib / libssl / d1_pkt.c

/* $OpenBSD: d1_pkt.c,v 1.63 2017/05/07 04:22:24 beck Exp $ */
/*
 * 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 <machine/endian.h>

#include <errno.h>
#include <stdio.h>

#include "ssl_locl.h"

#include <openssl/buffer.h>
#include <openssl/evp.h>

#include "pqueue.h"
#include "bytestring.h"

static int      do_dtls1_write(SSL *s, int type, const unsigned char *buf,
                    unsigned int len);


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

        if (sizeof(long) == 8)
                do {
                        long l;

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

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

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

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

static int have_handshake_fragment(SSL *s, int type, unsigned char *buf,
    int len, int peek);
static int dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap);
static void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap);
static DTLS1_BITMAP *dtls1_get_bitmap(SSL *s, SSL3_RECORD *rr,
    unsigned int *is_next_epoch);
static int dtls1_buffer_record(SSL *s, record_pqueue *q,
    unsigned char *priority);
static int dtls1_process_record(SSL *s);

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

        rdata = (DTLS1_RECORD_DATA *)item->data;

        free(s->s3->rbuf.buf);

        s->internal->packet = rdata->packet;
        s->internal->packet_length = rdata->packet_length;
        memcpy(&(s->s3->rbuf), &(rdata->rbuf), sizeof(SSL3_BUFFER));
        memcpy(&(S3I(s)->rrec), &(rdata->rrec), sizeof(SSL3_RECORD));

        /* Set proper sequence number for mac calculation */
        memcpy(&(S3I(s)->read_sequence[2]), &(rdata->packet[5]), 6);

        return (1);
}


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

        /* Limit the size of the queue to prevent DOS attacks */
        if (pqueue_size(queue->q) >= 100)
                return 0;

        rdata = malloc(sizeof(DTLS1_RECORD_DATA));
        item = pitem_new(priority, rdata);
        if (rdata == NULL || item == NULL)
                goto init_err;

        rdata->packet = s->internal->packet;
        rdata->packet_length = s->internal->packet_length;
        memcpy(&(rdata->rbuf), &(s->s3->rbuf), sizeof(SSL3_BUFFER));
        memcpy(&(rdata->rrec), &(S3I(s)->rrec), sizeof(SSL3_RECORD));

        item->data = rdata;


        s->internal->packet = NULL;
        s->internal->packet_length = 0;
        memset(&(s->s3->rbuf), 0, sizeof(SSL3_BUFFER));
        memset(&(S3I(s)->rrec), 0, sizeof(SSL3_RECORD));

        if (!ssl3_setup_buffers(s))
                goto err;

        /* insert should not fail, since duplicates are dropped */
        if (pqueue_insert(queue->q, item) == NULL)
                goto err;

        return (1);

err:
        free(rdata->rbuf.buf);

init_err:
        SSLerror(s, ERR_R_INTERNAL_ERROR);
        free(rdata);
        pitem_free(item);
        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);

                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), \
                       &((D1I(s))->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), \
                       &((D1I(s))->processed_rcds))

static int
dtls1_process_buffered_records(SSL *s)
{
        pitem *item;

        item = pqueue_peek(D1I(s)->unprocessed_rcds.q);
        if (item) {
                /* Check if epoch is current. */
                if (D1I(s)->unprocessed_rcds.epoch != D1I(s)->r_epoch)
                        return (1);
                /* Nothing to do. */

                /* Process all the records. */
                while (pqueue_peek(D1I(s)->unprocessed_rcds.q)) {
                        dtls1_get_unprocessed_record(s);
                        if (! dtls1_process_record(s))
                                return (0);
                        if (dtls1_buffer_record(s, &(D1I(s)->processed_rcds),
                            S3I(s)->rrec.seq_num) < 0)
                                return (-1);
                }
        }

    /* sync epoch numbers once all the unprocessed records
     * have been processed */
        D1I(s)->processed_rcds.epoch = D1I(s)->r_epoch;
        D1I(s)->unprocessed_rcds.epoch = D1I(s)->r_epoch + 1;

        return (1);
}

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

        rr = &(S3I(s)->rrec);
        sess = s->session;

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

        /* ok, we can now read from 's->internal->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;
                SSLerror(s, SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
                goto f_err;
        }

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

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


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

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

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

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

                i = tls1_mac(s, md, 0 /* not send */);
                if (i < 0 || mac == NULL || timingsafe_memcmp(md, mac, (size_t)mac_size) != 0)
                        enc_err = -1;
                if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size)
                        enc_err = -1;
        }

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

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

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

        /* we have pulled in a full packet so zero things */
        s->internal->packet_length = 0;
        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->internal->rrec.type    - is the type of record
 * ssl->s3->internal->rrec.data,         - data
 * ssl->s3->internal->rrec.length, - number of bytes
 */
/* used only by dtls1_read_bytes */
int
dtls1_get_record(SSL *s)
{
        SSL3_RECORD *rr;
        unsigned char *p = NULL;
        DTLS1_BITMAP *bitmap;
        unsigned int is_next_epoch;
        int n;

        rr = &(S3I(s)->rrec);

        /* The epoch may have changed.  If so, process all the
         * pending records.  This is a non-blocking operation. */
        if (dtls1_process_buffered_records(s) < 0)
                return (-1);

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

        /* get something from the wire */
        if (0) {
again:
                /* dump this record on all retries */
                rr->length = 0;
                s->internal->packet_length = 0;
        }

        /* check if we have the header */
        if ((s->internal->rstate != SSL_ST_READ_BODY) ||
            (s->internal->packet_length < DTLS1_RT_HEADER_LENGTH)) {
                CBS header, seq_no;
                uint16_t epoch, len, ssl_version;
                uint8_t type;

                n = ssl3_packet_read(s, DTLS1_RT_HEADER_LENGTH);
                if (n <= 0)
                        return (n);

                /* If this packet contained a partial record, dump it. */
                if (n != DTLS1_RT_HEADER_LENGTH)
                        goto again;

                s->internal->rstate = SSL_ST_READ_BODY;

                CBS_init(&header, s->internal->packet, s->internal->packet_length);

                /* Pull apart the header into the DTLS1_RECORD */
                if (!CBS_get_u8(&header, &type))
                        goto again;
                if (!CBS_get_u16(&header, &ssl_version))
                        goto again;

                /* sequence number is 64 bits, with top 2 bytes = epoch */
                if (!CBS_get_u16(&header, &epoch) ||
                    !CBS_get_bytes(&header, &seq_no, 6))
                        goto again;

                if (!CBS_write_bytes(&seq_no, &(S3I(s)->read_sequence[2]),
                    sizeof(S3I(s)->read_sequence) - 2, NULL))
                        goto again;
                if (!CBS_get_u16(&header, &len))
                        goto again;

                rr->type = type;
                rr->epoch = epoch;
                rr->length = len;

                /* unexpected version, silently discard */
                if (!s->internal->first_packet && ssl_version != s->version)
                        goto again;

                /* wrong version, silently discard record */
                if ((ssl_version & 0xff00) != (s->version & 0xff00))
                        goto again;

                /* record too long, silently discard it */
                if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH)
                        goto again;

                /* now s->internal->rstate == SSL_ST_READ_BODY */
                p = (unsigned char *)CBS_data(&header);
        }

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

        n = ssl3_packet_extend(s, DTLS1_RT_HEADER_LENGTH + rr->length);
        if (n <= 0)
                return (n);

        /* If this packet contained a partial record, dump it. */
        if (n != DTLS1_RT_HEADER_LENGTH + rr->length)
                goto again;

        s->internal->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)
                goto again;

        /*
         * 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 (!(D1I(s)->listen && rr->type == SSL3_RT_HANDSHAKE &&
            p != NULL && *p == SSL3_MT_CLIENT_HELLO) &&
            !dtls1_record_replay_check(s, bitmap))
                goto again;

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

        /* If this record is from the next epoch (either HM or ALERT),
         * and a handshake is currently in progress, buffer it since it
         * cannot be processed at this time. However, do not buffer
         * anything while listening.
         */
        if (is_next_epoch) {
                if ((SSL_in_init(s) || s->internal->in_handshake) && !D1I(s)->listen) {
                        if (dtls1_buffer_record(s, &(D1I(s)->unprocessed_rcds),
                            rr->seq_num) < 0)
                                return (-1);
                        /* Mark receipt of record. */
                        dtls1_record_bitmap_update(s, bitmap);
                }
                goto again;
        }

        if (!dtls1_process_record(s))
                goto again;

        /* Mark receipt of record. */
        dtls1_record_bitmap_update(s, bitmap);

        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);

        if ((type &&
             type != SSL3_RT_APPLICATION_DATA && type != SSL3_RT_HANDSHAKE) ||
            (peek && (type != SSL3_RT_APPLICATION_DATA))) {
                SSLerror(s, 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 D1I(s)->handshake_fragment_len == 0 if type == SSL3_RT_HANDSHAKE. */

        if (!s->internal->in_handshake && SSL_in_init(s))
        {
                /* type == SSL3_RT_APPLICATION_DATA */
                i = s->internal->handshake_func(s);
                if (i < 0)
                        return (i);
                if (i == 0) {
                        SSLerror(s, SSL_R_SSL_HANDSHAKE_FAILURE);
                        return (-1);
                }
        }

start:
        s->internal->rwstate = SSL_NOTHING;

        /* S3I(s)->rrec.type        - is the type of record
         * S3I(s)->rrec.data,    - data
         * S3I(s)->rrec.off,     - offset into 'data' for next read
         * S3I(s)->rrec.length,  - number of bytes. */
        rr = &(S3I(s)->rrec);

        /* We are not handshaking and have no data yet,
         * so process data buffered during the last handshake
         * in advance, if any.
         */
        if (S3I(s)->hs.state == SSL_ST_OK && rr->length == 0) {
                pitem *item;
                item = pqueue_pop(D1I(s)->buffered_app_data.q);
                if (item) {

                        dtls1_copy_record(s, item);

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

        if (D1I(s)->listen && rr->type != SSL3_RT_HANDSHAKE) {
                rr->length = 0;
                goto start;
        }

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

        if (S3I(s)->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.
                 */
                if (dtls1_buffer_record(s, &(D1I(s)->buffered_app_data),
                    rr->seq_num) < 0) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        return (-1);
                }
                rr->length = 0;
                goto start;
        }

        /* If the other end has shut down, throw anything we read away
         * (even in 'peek' mode) */
        if (s->internal->shutdown & SSL_RECEIVED_SHUTDOWN) {
                rr->length = 0;
                s->internal->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;
                        SSLerror(s, 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->internal->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 D1I(s)->handshake_fragment;
                        dest = D1I(s)->handshake_fragment;
                        dest_len = &D1I(s)->handshake_fragment_len;
                } else if (rr->type == SSL3_RT_ALERT) {
                        dest_maxlen = sizeof(D1I(s)->alert_fragment);
                        dest = D1I(s)->alert_fragment;
                        dest_len = &D1I(s)->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;
                                S3I(s)->in_read_app_data = 2;
                                bio = SSL_get_rbio(s);
                                s->internal->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;
                        SSLerror(s, 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->internal->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;
                }
        }

        /* D1I(s)->handshake_fragment_len == 12  iff  rr->type == SSL3_RT_HANDSHAKE;
         * D1I(s)->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) &&
            (D1I(s)->handshake_fragment_len >= DTLS1_HM_HEADER_LENGTH) &&
            (D1I(s)->handshake_fragment[0] == SSL3_MT_HELLO_REQUEST) &&
            (s->session != NULL) && (s->session->cipher != NULL)) {
                D1I(s)->handshake_fragment_len = 0;

                if ((D1I(s)->handshake_fragment[1] != 0) ||
                    (D1I(s)->handshake_fragment[2] != 0) ||
                    (D1I(s)->handshake_fragment[3] != 0)) {
                        al = SSL_AD_DECODE_ERROR;
                        SSLerror(s, SSL_R_BAD_HELLO_REQUEST);
                        goto err;
                }

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

                if (s->internal->msg_callback)
                        s->internal->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
                D1I(s)->handshake_fragment, 4, s, s->internal->msg_callback_arg);

                if (SSL_is_init_finished(s) &&
                    !(s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS) &&
                    !S3I(s)->renegotiate) {
                        D1I(s)->handshake_read_seq++;
                        s->internal->new_session = 1;
                        ssl3_renegotiate(s);
                        if (ssl3_renegotiate_check(s)) {
                                i = s->internal->handshake_func(s);
                                if (i < 0)
                                        return (i);
                                if (i == 0) {
                                        SSLerror(s, SSL_R_SSL_HANDSHAKE_FAILURE);
                                        return (-1);
                                }

                                if (!(s->internal->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->internal->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 (D1I(s)->alert_fragment_len >= DTLS1_AL_HEADER_LENGTH) {
                int alert_level = D1I(s)->alert_fragment[0];
                int alert_descr = D1I(s)->alert_fragment[1];

                D1I(s)->alert_fragment_len = 0;

                if (s->internal->msg_callback)
                        s->internal->msg_callback(0, s->version, SSL3_RT_ALERT,
                D1I(s)->alert_fragment, 2, s, s->internal->msg_callback_arg);

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

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

                if (alert_level == 1) /* warning */
                {
                        S3I(s)->warn_alert = alert_descr;
                        if (alert_descr == SSL_AD_CLOSE_NOTIFY) {
                                s->internal->shutdown |= SSL_RECEIVED_SHUTDOWN;
                                return (0);
                        }
                } else if (alert_level == 2) /* fatal */
                {
                        s->internal->rwstate = SSL_NOTHING;
                        S3I(s)->fatal_alert = alert_descr;
                        SSLerror(s, SSL_AD_REASON_OFFSET + alert_descr);
                        ERR_asprintf_error_data("SSL alert number %d",
                            alert_descr);
                        s->internal->shutdown|=SSL_RECEIVED_SHUTDOWN;
                        SSL_CTX_remove_session(s->ctx, s->session);
                        return (0);
                } else {
                        al = SSL_AD_ILLEGAL_PARAMETER;
                        SSLerror(s, SSL_R_UNKNOWN_ALERT_TYPE);
                        goto f_err;
                }

                goto start;
        }

        if (s->internal->shutdown & SSL_SENT_SHUTDOWN) /* but we have not received a shutdown */
        {
                s->internal->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 ((rr->length != ccs_hdr_len) ||
                    (rr->off != 0) || (rr->data[0] != SSL3_MT_CCS)) {
                        i = SSL_AD_ILLEGAL_PARAMETER;
                        SSLerror(s, SSL_R_BAD_CHANGE_CIPHER_SPEC);
                        goto err;
                }

                rr->length = 0;

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

                /* We can't process a CCS now, because previous handshake
                 * messages are still missing, so just drop it.
                 */
                if (!D1I(s)->change_cipher_spec_ok) {
                        goto start;
                }

                D1I(s)->change_cipher_spec_ok = 0;

                S3I(s)->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);

                goto start;
        }

        /* Unexpected handshake message (Client Hello, or protocol violation) */
        if ((D1I(s)->handshake_fragment_len >= DTLS1_HM_HEADER_LENGTH) &&
            !s->internal->in_handshake) {
                struct hm_header_st msg_hdr;

                /* this may just be a stale retransmit */
                if (!dtls1_get_message_header(rr->data, &msg_hdr))
                        return -1;
                if (rr->epoch != D1I(s)->r_epoch) {
                        rr->length = 0;
                        goto start;
                }

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

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

                if (((S3I(s)->hs.state&SSL_ST_MASK) == SSL_ST_OK) &&
                    !(s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS)) {
                        S3I(s)->hs.state = s->server ? SSL_ST_ACCEPT : SSL_ST_CONNECT;
                        s->internal->renegotiate = 1;
                        s->internal->new_session = 1;
                }
                i = s->internal->handshake_func(s);
                if (i < 0)
                        return (i);
                if (i == 0) {
                        SSLerror(s, SSL_R_SSL_HANDSHAKE_FAILURE);
                        return (-1);
                }

                if (!(s->internal->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->internal->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:
                /* TLS just ignores unknown message types */
                if (s->version == TLS1_VERSION) {
                        rr->length = 0;
                        goto start;
                }
                al = SSL_AD_UNEXPECTED_MESSAGE;
                SSLerror(s, 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->internal->in_handshake is set, but that
                 * should not happen when type != rr->type */
                al = SSL_AD_UNEXPECTED_MESSAGE;
                SSLerror(s, 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 (S3I(s)->in_read_app_data &&
                    (S3I(s)->total_renegotiations != 0) &&
                    (((S3I(s)->hs.state & SSL_ST_CONNECT) &&
                    (S3I(s)->hs.state >= SSL3_ST_CW_CLNT_HELLO_A) &&
                    (S3I(s)->hs.state <= SSL3_ST_CR_SRVR_HELLO_A)) || (
                    (S3I(s)->hs.state & SSL_ST_ACCEPT) &&
                    (S3I(s)->hs.state <= SSL3_ST_SW_HELLO_REQ_A) &&
                    (S3I(s)->hs.state >= SSL3_ST_SR_CLNT_HELLO_A)))) {
                        S3I(s)->in_read_app_data = 2;
                        return (-1);
                } else {
                        al = SSL_AD_UNEXPECTED_MESSAGE;
                        SSLerror(s, 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->internal->in_handshake)
        {
                i = s->internal->handshake_func(s);
                if (i < 0)
                        return (i);
                if (i == 0) {
                        SSLerror(s, SSL_R_SSL_HANDSHAKE_FAILURE);
                        return -1;
                }
        }

        if (len > SSL3_RT_MAX_PLAIN_LENGTH) {
                SSLerror(s, 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) && (D1I(s)->handshake_fragment_len > 0))
                /* (partially) satisfy request from storage */
        {
                unsigned char *src = D1I(s)->handshake_fragment;
                unsigned char *dst = buf;
                unsigned int k, n;

                /* peek == 0 */
                n = 0;
                while ((len > 0) && (D1I(s)->handshake_fragment_len > 0)) {
                        *dst++ = *src++;
                        len--;
                        D1I(s)->handshake_fragment_len--;
                        n++;
                }
                /* move any remaining fragment bytes: */
                for (k = 0; k < D1I(s)->handshake_fragment_len; k++)
                        D1I(s)->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->internal->rwstate = SSL_NOTHING;
        i = do_dtls1_write(s, type, buf, len);
        return i;
}

int
do_dtls1_write(SSL *s, int type, const unsigned char *buf, unsigned int len)
{
        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)
                return 0;

        wr = &(S3I(s)->wrec);
        wb = &(s->s3->wbuf);
        sess = s->session;

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

        if (clear)
                mac_size = 0;
        else {
                mac_size = EVP_MD_CTX_size(s->internal->write_hash);
                if (mac_size < 0)
                        goto err;
        }

        /* DTLS implements explicit IV, so no need for empty fragments. */

        p = wb->buf + prefix_len;

        /* write the header */

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

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

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

        p += 10;

        /* lets setup the record stuff. */

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

        memcpy(wr->data, wr->input, wr->length);
        wr->input = wr->data;

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

        if (mac_size != 0) {
                if (tls1_mac(s, &(p[wr->length + bs]), 1) < 0)
                        goto err;
                wr->length += mac_size;
        }

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


        /* ssl3_enc can only have an error on read */
        if (bs) /* bs != 0 in case of CBC */
        {
                arc4random_buf(p, bs);
                /* master IV and last CBC residue stand for
                 * the rest of randomness */
                wr->length += bs;
        }

        s->method->internal->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(D1I(s)->w_epoch, pseq);

        /* XDTLS: ?? */
/*      else
        s2n(D1I(s)->handshake_epoch, pseq);
*/

        memcpy(pseq, &(S3I(s)->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;

        tls1_record_sequence_increment(S3I(s)->write_sequence);

        /* 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 */
        S3I(s)->wpend_tot = len;
        S3I(s)->wpend_buf = buf;
        S3I(s)->wpend_type = type;
        S3I(s)->wpend_ret = len;

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



static int
dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap)
{
        int cmp;
        unsigned int shift;
        const unsigned char *seq = S3I(s)->read_sequence;

        cmp = satsub64be(seq, bitmap->max_seq_num);
        if (cmp > 0) {
                memcpy (S3I(s)->rrec.seq_num, seq, 8);
                return 1; /* this record in new */
        }
        shift = -cmp;
        if (shift >= sizeof(bitmap->map)*8)
                return 0; /* stale, outside the window */
        else if (bitmap->map & (1UL << shift))
                return 0; /* record previously received */

        memcpy(S3I(s)->rrec.seq_num, seq, 8);
        return 1;
}


static void
dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap)
{
        int cmp;
        unsigned int shift;
        const unsigned char *seq = S3I(s)->read_sequence;

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


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

        s->s3->alert_dispatch = 0;

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

#ifdef DTLS1_AD_MISSING_HANDSHAKE_MESSAGE
        if (s->s3->send_alert[1] == DTLS1_AD_MISSING_HANDSHAKE_MESSAGE) {
                s2n(D1I(s)->handshake_read_seq, ptr);
                l2n3(D1I(s)->r_msg_hdr.frag_off, ptr);
        }
#endif

        i = do_dtls1_write(s, SSL3_RT_ALERT, &buf[0], sizeof(buf));
        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->internal->msg_callback)
                        s->internal->msg_callback(1, s->version, SSL3_RT_ALERT,
                            s->s3->send_alert, 2, s, s->internal->msg_callback_arg);

                if (s->internal->info_callback != NULL)
                        cb = s->internal->info_callback;
                else if (s->ctx->internal->info_callback != NULL)
                        cb = s->ctx->internal->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 == D1I(s)->r_epoch)
                return &D1I(s)->bitmap;

        /* Only HM and ALERT messages can be from the next epoch */
        else if (rr->epoch == (unsigned long)(D1I(s)->r_epoch + 1) &&
                (rr->type == SSL3_RT_HANDSHAKE || rr->type == SSL3_RT_ALERT)) {
                *is_next_epoch = 1;
                return &D1I(s)->next_bitmap;
        }

        return NULL;
}

void
dtls1_reset_seq_numbers(SSL *s, int rw)
{
        unsigned char *seq;
        unsigned int seq_bytes = sizeof(S3I(s)->read_sequence);

        if (rw & SSL3_CC_READ) {
                seq = S3I(s)->read_sequence;
                D1I(s)->r_epoch++;
                memcpy(&(D1I(s)->bitmap), &(D1I(s)->next_bitmap), sizeof(DTLS1_BITMAP));
                memset(&(D1I(s)->next_bitmap), 0x00, sizeof(DTLS1_BITMAP));
        } else {
                seq = S3I(s)->write_sequence;
                memcpy(D1I(s)->last_write_sequence, seq, sizeof(S3I(s)->write_sequence));
                D1I(s)->w_epoch++;
        }

        memset(seq, 0x00, seq_bytes);
}