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

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

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

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

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

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

    rdata = OPENSSL_malloc(sizeof(*rdata));
    item = pitem_new(priority, rdata);
    if (rdata == NULL || item == NULL) {
        OPENSSL_free(rdata);
        pitem_free(item);
        SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
        return -1;
    }

    rdata->packet = s->rlayer.packet;
    rdata->packet_length = s->rlayer.packet_length;
    memcpy(&(rdata->rbuf), &s->rlayer.rbuf, sizeof(SSL3_BUFFER));
    memcpy(&(rdata->rrec), &s->rlayer.rrec, sizeof(SSL3_RECORD));

    item->data = rdata;

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

    s->rlayer.packet = NULL;
    s->rlayer.packet_length = 0;
    memset(&s->rlayer.rbuf, 0, sizeof(s->rlayer.rbuf));
    memset(&s->rlayer.rrec, 0, sizeof(s->rlayer.rrec));

    if (!ssl3_setup_buffers(s)) {
        SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
        OPENSSL_free(rdata->rbuf.buf);
        OPENSSL_free(rdata);
        pitem_free(item);
        return (-1);
    }

    /* insert should not fail, since duplicates are dropped */
    if (pqueue_insert(queue->q, item) == NULL) {
        SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
        OPENSSL_free(rdata->rbuf.buf);
        OPENSSL_free(rdata);
        pitem_free(item);
        return (-1);
    }

    return (1);
}

void dtls1_start_timer(SSL *s)
{
#ifndef OPENSSL_NO_SCTP
    /* Disable timer for SCTP */
    if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
        memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
        return;
    }
#endif

    /* If timer is not set, initialize duration with 1 second */
    if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
        s->d1->timeout_duration = 1;
    }

    /* Set timeout to current time */
    get_current_time(&(s->d1->next_timeout));

    /* Add duration to current time */
    s->d1->next_timeout.tv_sec += s->d1->timeout_duration;
    BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
             &(s->d1->next_timeout));
}

int dtls1_shutdown(SSL *s)
{
    int ret;
#ifndef OPENSSL_NO_SCTP
    BIO *wbio;

    wbio = SSL_get_wbio(s);
    if (wbio != NULL && BIO_dgram_is_sctp(wbio) &&
        !(s->shutdown & SSL_SENT_SHUTDOWN)) {
        ret = BIO_dgram_sctp_wait_for_dry(wbio);
        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;
}

//.........这里部分代码省略.........
				}
			s->type=SSL_ST_ACCEPT;

			if (s->init_buf == NULL)
				{
				if ((buf=BUF_MEM_new()) == NULL)
					{
					ret= -1;
					goto end;
					}
				if (!BUF_MEM_grow(buf,SSL3_RT_MAX_PLAIN_LENGTH))
					{
					ret= -1;
					goto end;
					}
				s->init_buf=buf;
				}

			if (!ssl3_setup_buffers(s))
				{
				ret= -1;
				goto end;
				}

			s->init_num=0;

			if (s->state != SSL_ST_RENEGOTIATE)
				{
				/* Ok, we now need to push on a buffering BIO so that
				 * the output is sent in a way that TCP likes :-)
				 * ...but not with SCTP :-)
				 */
#ifndef OPENSSL_NO_SCTP
				if (!BIO_dgram_is_sctp(SSL_get_wbio(s)))
#endif
					if (!ssl_init_wbio_buffer(s,1)) { ret= -1; goto end; }

				ssl3_init_finished_mac(s);
				s->state=SSL3_ST_SR_CLNT_HELLO_A;
				s->ctx->stats.sess_accept++;
				}
			else
				{
				/* s->state == SSL_ST_RENEGOTIATE,
				 * we will just send a HelloRequest */
				s->ctx->stats.sess_accept_renegotiate++;
				s->state=SSL3_ST_SW_HELLO_REQ_A;
				}

			break;

		case SSL3_ST_SW_HELLO_REQ_A:
		case SSL3_ST_SW_HELLO_REQ_B:

			s->shutdown=0;
			dtls1_clear_record_buffer(s);
			dtls1_start_timer(s);
			ret=ssl3_send_hello_request(s);
			if (ret <= 0) goto end;
			s->s3->tmp.next_state=SSL3_ST_SR_CLNT_HELLO_A;
			s->state=SSL3_ST_SW_FLUSH;
			s->init_num=0;

			ssl3_init_finished_mac(s);
			break;

//.........这里部分代码省略.........
				BIO_set_retry_read(SSL_get_rbio(s));
				ret = -1;
				goto end;
			}

			s->state=s->d1->next_state;
			break;
#endif

		case SSL3_ST_CW_CLNT_HELLO_A:
		case SSL3_ST_CW_CLNT_HELLO_B:

			s->shutdown=0;

			/* every DTLS ClientHello resets Finished MAC */
			ssl3_init_finished_mac(s);

			dtls1_start_timer(s);
			ret=dtls1_client_hello(s);
			if (ret <= 0) goto end;

			if ( s->d1->send_cookie)
				{
				s->state=SSL3_ST_CW_FLUSH;
				s->s3->tmp.next_state=SSL3_ST_CR_SRVR_HELLO_A;
				}
			else
				s->state=SSL3_ST_CR_SRVR_HELLO_A;

			s->init_num=0;

#ifndef OPENSSL_NO_SCTP
			/* Disable buffering for SCTP */
			if (!BIO_dgram_is_sctp(SSL_get_wbio(s)))
				{
#endif
				/* turn on buffering for the next lot of output */
				if (s->bbio != s->wbio)
					s->wbio=BIO_push(s->bbio,s->wbio);
#ifndef OPENSSL_NO_SCTP
				}
#endif

			break;

		case SSL3_ST_CR_SRVR_HELLO_A:
		case SSL3_ST_CR_SRVR_HELLO_B:
			ret=ssl3_get_server_hello(s);
			if (ret <= 0) goto end;
			else
				{
				if (s->hit)
					{
#ifndef OPENSSL_NO_SCTP
					/* Add new shared key for SCTP-Auth,
					 * will be ignored if no SCTP used.
					 */
					snprintf((char*) labelbuffer, sizeof(DTLS1_SCTP_AUTH_LABEL),
					         DTLS1_SCTP_AUTH_LABEL);

					SSL_export_keying_material(s, sctpauthkey,
					                           sizeof(sctpauthkey), labelbuffer,
					                           sizeof(labelbuffer), NULL, 0, 0);

					BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_ADD_AUTH_KEY,
							 sizeof(sctpauthkey), sctpauthkey);

/*-
 * 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) or renegotiation requests. ChangeCipherSpec
 * messages are treated as if they were handshake messages *if* the |recd_type|
 * argument is non NULL.
 * 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, int *recvd_type, unsigned char *buf,
                     size_t len, int peek, size_t *readbytes)
{
    int i, j, iret;
    size_t n;
    SSL3_RECORD *rr;
    void (*cb) (const SSL *ssl, int type2, int val) = NULL;

    if (!SSL3_BUFFER_is_initialised(&s->rlayer.rbuf)) {
        /* Not initialized yet */
        if (!ssl3_setup_buffers(s)) {
            /* SSLfatal() already called */
            return -1;
        }
    }

    if ((type && (type != SSL3_RT_APPLICATION_DATA) &&
         (type != SSL3_RT_HANDSHAKE)) ||
        (peek && (type != SSL3_RT_APPLICATION_DATA))) {
        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_READ_BYTES,
                 ERR_R_INTERNAL_ERROR);
        return -1;
    }

    if (!ossl_statem_get_in_handshake(s) && SSL_in_init(s)) {
        /* type == SSL3_RT_APPLICATION_DATA */
        i = s->handshake_func(s);
        /* SSLfatal() already called if appropriate */
        if (i < 0)
            return i;
        if (i == 0)
            return -1;
    }

 start:
    s->rwstate = SSL_NOTHING;

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

    /*
     * We are not handshaking and have no data yet, so process data buffered
     * during the last handshake in advance, if any.
     */
    if (SSL_is_init_finished(s) && SSL3_RECORD_get_length(rr) == 0) {
        pitem *item;
        item = pqueue_pop(s->rlayer.d->buffered_app_data.q);
        if (item) {
#ifndef OPENSSL_NO_SCTP
            /* Restore bio_dgram_sctp_rcvinfo struct */
            if (BIO_dgram_is_sctp(SSL_get_rbio(s))) {
                DTLS1_RECORD_DATA *rdata = (DTLS1_RECORD_DATA *)item->data;
                BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SCTP_SET_RCVINFO,
                         sizeof(rdata->recordinfo), &rdata->recordinfo);
            }
#endif

            dtls1_copy_record(s, item);

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

    /* Check for timeout */
    if (dtls1_handle_timeout(s) > 0) {
//.........这里部分代码省略.........

int dtls1_process_buffered_records(SSL *s)
{
    pitem *item;
    SSL3_BUFFER *rb;
    SSL3_RECORD *rr;
    DTLS1_BITMAP *bitmap;
    unsigned int is_next_epoch;
    int replayok = 1;

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

        rr = RECORD_LAYER_get_rrec(&s->rlayer);

        rb = RECORD_LAYER_get_rbuf(&s->rlayer);

        if (SSL3_BUFFER_get_left(rb) > 0) {
            /*
             * We've still got data from the current packet to read. There could
             * be a record from the new epoch in it - so don't overwrite it
             * with the unprocessed records yet (we'll do it when we've
             * finished reading the current packet).
             */
            return 1;
        }

        /* Process all the records. */
        while (pqueue_peek(s->rlayer.d->unprocessed_rcds.q)) {
            dtls1_get_unprocessed_record(s);
            bitmap = dtls1_get_bitmap(s, rr, &is_next_epoch);
            if (bitmap == NULL) {
                /*
                 * Should not happen. This will only ever be NULL when the
                 * current record is from a different epoch. But that cannot
                 * be the case because we already checked the epoch above
                 */
                 SSLfatal(s, SSL_AD_INTERNAL_ERROR,
                          SSL_F_DTLS1_PROCESS_BUFFERED_RECORDS,
                          ERR_R_INTERNAL_ERROR);
                 return 0;
            }
#ifndef OPENSSL_NO_SCTP
            /* Only do replay check if no SCTP bio */
            if (!BIO_dgram_is_sctp(SSL_get_rbio(s)))
#endif
            {
                /*
                 * Check whether this is a repeat, or aged record. We did this
                 * check once already when we first received the record - but
                 * we might have updated the window since then due to
                 * records we subsequently processed.
                 */
                replayok = dtls1_record_replay_check(s, bitmap);
            }

            if (!replayok || !dtls1_process_record(s, bitmap)) {
                if (ossl_statem_in_error(s)) {
                    /* dtls1_process_record called SSLfatal() */
                    return -1;
                }
                /* dump this record */
                rr->length = 0;
                RECORD_LAYER_reset_packet_length(&s->rlayer);
                continue;
            }

            if (dtls1_buffer_record(s, &(s->rlayer.d->processed_rcds),
                    SSL3_RECORD_get_seq_num(s->rlayer.rrec)) < 0) {
                /* SSLfatal() already called */
                return 0;
            }
        }
    }

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

    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) or renegotiation requests. ChangeCipherSpec
 * messages are treated as if they were handshake messages *if* the |recd_type|
 * argument is non NULL.
 * 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, int *recvd_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 (!SSL3_BUFFER_is_initialised(&s->rlayer.rbuf)) {
        /* 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))) {
        SSLerr(SSL_F_DTLS1_READ_BYTES, ERR_R_INTERNAL_ERROR);
        return -1;
    }

    /*
     * check whether there's a handshake message (client hello?) waiting
     */
    if ((ret = have_handshake_fragment(s, type, buf, len))) {
        *recvd_type = SSL3_RT_HANDSHAKE;
        return ret;
    }

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

    if (!ossl_statem_get_in_handshake(s) && SSL_in_init(s))
    {
        /* type == SSL3_RT_APPLICATION_DATA */
        i = s->handshake_func(s);
        if (i < 0)
            return (i);
        if (i == 0) {
            SSLerr(SSL_F_DTLS1_READ_BYTES, SSL_R_SSL_HANDSHAKE_FAILURE);
            return (-1);
        }
    }

 start:
    s->rwstate = SSL_NOTHING;

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

    /*
     * We are not handshaking and have no data yet, so process data buffered
     * during the last handshake in advance, if any.
     */
    if (SSL_is_init_finished(s) && SSL3_RECORD_get_length(rr) == 0) {
        pitem *item;
        item = pqueue_pop(s->rlayer.d->buffered_app_data.q);
        if (item) {
#ifndef OPENSSL_NO_SCTP
            /* Restore bio_dgram_sctp_rcvinfo struct */
            if (BIO_dgram_is_sctp(SSL_get_rbio(s))) {
                DTLS1_RECORD_DATA *rdata = (DTLS1_RECORD_DATA *)item->data;
                BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SCTP_SET_RCVINFO,
                         sizeof(rdata->recordinfo), &rdata->recordinfo);
//.........这里部分代码省略.........

int
dtls1_accept(SSL *s)
{
	void (*cb)(const SSL *ssl, int type, int val) = NULL;
	unsigned long alg_k;
	int ret = -1;
	int new_state, state, skip = 0;
	int listen;
#ifndef OPENSSL_NO_SCTP
	unsigned char sctpauthkey[64];
	char labelbuffer[sizeof(DTLS1_SCTP_AUTH_LABEL)];
#endif

	ERR_clear_error();
	errno = 0;

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

	listen = s->d1->listen;

	/* init things to blank */
	s->in_handshake++;
	if (!SSL_in_init(s) || SSL_in_before(s))
		SSL_clear(s);

	s->d1->listen = listen;
#ifndef OPENSSL_NO_SCTP
	/* Notify SCTP BIO socket to enter handshake
	 * mode and prevent stream identifier other
	 * than 0. Will be ignored if no SCTP is used.
	 */
	BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
	    s->in_handshake, NULL);
#endif

	if (s->cert == NULL) {
		SSLerr(SSL_F_DTLS1_ACCEPT, SSL_R_NO_CERTIFICATE_SET);
		return (-1);
	}

	for (;;) {
		state = s->state;

		switch (s->state) {
		case SSL_ST_RENEGOTIATE:
			s->renegotiate = 1;
			/* s->state=SSL_ST_ACCEPT; */

		case SSL_ST_BEFORE:
		case SSL_ST_ACCEPT:
		case SSL_ST_BEFORE|SSL_ST_ACCEPT:
		case SSL_ST_OK|SSL_ST_ACCEPT:

			s->server = 1;
			if (cb != NULL)
				cb(s, SSL_CB_HANDSHAKE_START, 1);

			if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) {
				SSLerr(SSL_F_DTLS1_ACCEPT, ERR_R_INTERNAL_ERROR);
				return -1;
			}
			s->type = SSL_ST_ACCEPT;

			if (s->init_buf == NULL) {
				BUF_MEM *buf;
				if ((buf = BUF_MEM_new()) == NULL) {
					ret = -1;
					goto end;
				}
				if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
					BUF_MEM_free(buf);
					ret = -1;
					goto end;
				}
				s->init_buf = buf;
			}

			if (!ssl3_setup_buffers(s)) {
				ret = -1;
				goto end;
			}

			s->init_num = 0;

			if (s->state != SSL_ST_RENEGOTIATE) {
				/* Ok, we now need to push on a buffering BIO so that
				 * the output is sent in a way that TCP likes :-)
				 * ...but not with SCTP :-)
				 */
#ifndef OPENSSL_NO_SCTP
				if (!BIO_dgram_is_sctp(SSL_get_wbio(s)))
#endif
				if (!ssl_init_wbio_buffer(s, 1)) {
					ret = -1;
					goto end;
				}

//.........这里部分代码省略.........