Beispiel #1
0
/*-
 * 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) {
        goto start;
    } else if (ossl_statem_in_error(s)) {
        /* dtls1_handle_timeout() has failed with a fatal error */
        return -1;
    }

    /* get new packet if necessary */
    if ((SSL3_RECORD_get_length(rr) == 0)
        || (s->rlayer.rstate == SSL_ST_READ_BODY)) {
        RECORD_LAYER_set_numrpipes(&s->rlayer, 0);
        iret = dtls1_get_record(s);
        if (iret <= 0) {
            iret = dtls1_read_failed(s, iret);
            /*
             * Anything other than a timeout is an error. SSLfatal() already
             * called if appropriate.
             */
            if (iret <= 0)
                return iret;
            else
                goto start;
        }
        RECORD_LAYER_set_numrpipes(&s->rlayer, 1);
    }

    /*
     * Reset the count of consecutive warning alerts if we've got a non-empty
     * record that isn't an alert.
     */
    if (SSL3_RECORD_get_type(rr) != SSL3_RT_ALERT
            && SSL3_RECORD_get_length(rr) != 0)
        s->rlayer.alert_count = 0;

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

    if (s->s3.change_cipher_spec /* set when we receive ChangeCipherSpec,
                                  * reset by ssl3_get_finished */
        && (SSL3_RECORD_get_type(rr) != 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, &(s->rlayer.d->buffered_app_data),
                                SSL3_RECORD_get_seq_num(rr)) < 0) {
            /* SSLfatal() already called */
            return -1;
        }
        SSL3_RECORD_set_length(rr, 0);
        SSL3_RECORD_set_read(rr);
        goto start;
    }

    /*
     * If the other end has shut down, throw anything we read away (even in
     * 'peek' mode)
     */
    if (s->shutdown & SSL_RECEIVED_SHUTDOWN) {
        SSL3_RECORD_set_length(rr, 0);
        SSL3_RECORD_set_read(rr);
        s->rwstate = SSL_NOTHING;
        return 0;
    }

    if (type == SSL3_RECORD_get_type(rr)
        || (SSL3_RECORD_get_type(rr) == SSL3_RT_CHANGE_CIPHER_SPEC
            && type == SSL3_RT_HANDSHAKE && recvd_type != NULL)) {
        /*
         * SSL3_RT_APPLICATION_DATA or
         * SSL3_RT_HANDSHAKE or
         * SSL3_RT_CHANGE_CIPHER_SPEC
         */
        /*
         * 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)) {
            SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                     SSL_R_APP_DATA_IN_HANDSHAKE);
            return -1;
        }

        if (recvd_type != NULL)
            *recvd_type = SSL3_RECORD_get_type(rr);

        if (len == 0) {
            /*
             * Mark a zero length record as read. This ensures multiple calls to
             * SSL_read() with a zero length buffer will eventually cause
             * SSL_pending() to report data as being available.
             */
            if (SSL3_RECORD_get_length(rr) == 0)
                SSL3_RECORD_set_read(rr);
            return 0;
        }

        if (len > SSL3_RECORD_get_length(rr))
            n = SSL3_RECORD_get_length(rr);
        else
            n = len;

        memcpy(buf, &(SSL3_RECORD_get_data(rr)[SSL3_RECORD_get_off(rr)]), n);
        if (peek) {
            if (SSL3_RECORD_get_length(rr) == 0)
                SSL3_RECORD_set_read(rr);
        } else {
            SSL3_RECORD_sub_length(rr, n);
            SSL3_RECORD_add_off(rr, n);
            if (SSL3_RECORD_get_length(rr) == 0) {
                s->rlayer.rstate = SSL_ST_READ_HEADER;
                SSL3_RECORD_set_off(rr, 0);
                SSL3_RECORD_set_read(rr);
            }
        }
#ifndef OPENSSL_NO_SCTP
        /*
         * We might had to delay a close_notify alert because of reordered
         * app data. If there was an alert and there is no message to read
         * anymore, finally set shutdown.
         */
        if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
            s->d1->shutdown_received
            && !BIO_dgram_sctp_msg_waiting(SSL_get_rbio(s))) {
            s->shutdown |= SSL_RECEIVED_SHUTDOWN;
            return 0;
        }
#endif
        *readbytes = n;
        return 1;
    }

    /*
     * If we get here, then type != rr->type; if we have a handshake message,
     * then it was unexpected (Hello Request or Client Hello).
     */

    if (SSL3_RECORD_get_type(rr) == SSL3_RT_ALERT) {
        unsigned int alert_level, alert_descr;
        unsigned char *alert_bytes = SSL3_RECORD_get_data(rr)
                                     + SSL3_RECORD_get_off(rr);
        PACKET alert;

        if (!PACKET_buf_init(&alert, alert_bytes, SSL3_RECORD_get_length(rr))
                || !PACKET_get_1(&alert, &alert_level)
                || !PACKET_get_1(&alert, &alert_descr)
                || PACKET_remaining(&alert) != 0) {
            SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                     SSL_R_INVALID_ALERT);
            return -1;
        }

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

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

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

        if (alert_level == SSL3_AL_WARNING) {
            s->s3.warn_alert = alert_descr;
            SSL3_RECORD_set_read(rr);

            s->rlayer.alert_count++;
            if (s->rlayer.alert_count == MAX_WARN_ALERT_COUNT) {
                SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                         SSL_R_TOO_MANY_WARN_ALERTS);
                return -1;
            }

            if (alert_descr == SSL_AD_CLOSE_NOTIFY) {
#ifndef OPENSSL_NO_SCTP
                /*
                 * With SCTP and streams the socket may deliver app data
                 * after a close_notify alert. We have to check this first so
                 * that nothing gets discarded.
                 */
                if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
                    BIO_dgram_sctp_msg_waiting(SSL_get_rbio(s))) {
                    s->d1->shutdown_received = 1;
                    s->rwstate = SSL_READING;
                    BIO_clear_retry_flags(SSL_get_rbio(s));
                    BIO_set_retry_read(SSL_get_rbio(s));
                    return -1;
                }
#endif
                s->shutdown |= SSL_RECEIVED_SHUTDOWN;
                return 0;
            }
        } else if (alert_level == SSL3_AL_FATAL) {
            char tmp[16];

            s->rwstate = SSL_NOTHING;
            s->s3.fatal_alert = alert_descr;
            SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_DTLS1_READ_BYTES,
                     SSL_AD_REASON_OFFSET + alert_descr);
            BIO_snprintf(tmp, sizeof tmp, "%d", alert_descr);
            ERR_add_error_data(2, "SSL alert number ", tmp);
            s->shutdown |= SSL_RECEIVED_SHUTDOWN;
            SSL3_RECORD_set_read(rr);
            SSL_CTX_remove_session(s->session_ctx, s->session);
            return 0;
        } else {
            SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_DTLS1_READ_BYTES,
                     SSL_R_UNKNOWN_ALERT_TYPE);
            return -1;
        }

        goto start;
    }

    if (s->shutdown & SSL_SENT_SHUTDOWN) { /* but we have not received a
                                            * shutdown */
        s->rwstate = SSL_NOTHING;
        SSL3_RECORD_set_length(rr, 0);
        SSL3_RECORD_set_read(rr);
        return 0;
    }

    if (SSL3_RECORD_get_type(rr) == SSL3_RT_CHANGE_CIPHER_SPEC) {
        /*
         * We can't process a CCS now, because previous handshake messages
         * are still missing, so just drop it.
         */
        SSL3_RECORD_set_length(rr, 0);
        SSL3_RECORD_set_read(rr);
        goto start;
    }

    /*
     * Unexpected handshake message (Client Hello, or protocol violation)
     */
    if ((SSL3_RECORD_get_type(rr) == SSL3_RT_HANDSHAKE) &&
            !ossl_statem_get_in_handshake(s)) {
        struct hm_header_st msg_hdr;

        /*
         * This may just be a stale retransmit. Also sanity check that we have
         * at least enough record bytes for a message header
         */
        if (SSL3_RECORD_get_epoch(rr) != s->rlayer.d->r_epoch
                || SSL3_RECORD_get_length(rr) < DTLS1_HM_HEADER_LENGTH) {
            SSL3_RECORD_set_length(rr, 0);
            SSL3_RECORD_set_read(rr);
            goto start;
        }

        dtls1_get_message_header(rr->data, &msg_hdr);

        /*
         * 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) {
                /* SSLfatal) already called */
                return -1;
            }

            if (dtls1_retransmit_buffered_messages(s) <= 0) {
                /* Fail if we encountered a fatal error */
                if (ossl_statem_in_error(s))
                    return -1;
            }
            SSL3_RECORD_set_length(rr, 0);
            SSL3_RECORD_set_read(rr);
            if (!(s->mode & SSL_MODE_AUTO_RETRY)) {
                if (SSL3_BUFFER_get_left(&s->rlayer.rbuf) == 0) {
                    /* no read-ahead left? */
                    BIO *bio;

                    s->rwstate = SSL_READING;
                    bio = SSL_get_rbio(s);
                    BIO_clear_retry_flags(bio);
                    BIO_set_retry_read(bio);
                    return -1;
                }
            }
            goto start;
        }

        /*
         * To get here we must be trying to read app data but found handshake
         * data. But if we're trying to read app data, and we're not in init
         * (which is tested for at the top of this function) then init must be
         * finished
         */
        if (!ossl_assert(SSL_is_init_finished(s))) {
            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_READ_BYTES,
                     ERR_R_INTERNAL_ERROR);
            return -1;
        }

        /* We found handshake data, so we're going back into init */
        ossl_statem_set_in_init(s, 1);

        i = s->handshake_func(s);
        /* SSLfatal() called if appropriate */
        if (i < 0)
            return i;
        if (i == 0)
            return -1;

        if (!(s->mode & SSL_MODE_AUTO_RETRY)) {
            if (SSL3_BUFFER_get_left(&s->rlayer.rbuf) == 0) {
                /* no read-ahead left? */
                BIO *bio;
                /*
                 * In the case where we try to read application data, but we
                 * trigger an SSL handshake, we return -1 with the retry
                 * option set.  Otherwise renegotiation may cause nasty
                 * problems in the blocking world
                 */
                s->rwstate = SSL_READING;
                bio = SSL_get_rbio(s);
                BIO_clear_retry_flags(bio);
                BIO_set_retry_read(bio);
                return -1;
            }
        }
        goto start;
    }

    switch (SSL3_RECORD_get_type(rr)) {
    default:
        SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                 SSL_R_UNEXPECTED_RECORD);
        return -1;
    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 ossl_statem_get_in_handshake(s) is true, but
         * that should not happen when type != rr->type
         */
        SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                 ERR_R_INTERNAL_ERROR);
        return -1;
    case SSL3_RT_APPLICATION_DATA:
        /*
         * At this point, we were expecting handshake data, but have
         * application data.  If the library was running inside ssl3_read()
         * (i.e. in_read_app_data is set) and it makes sense to read
         * application data at this point (session renegotiation not yet
         * started), we will indulge it.
         */
        if (s->s3.in_read_app_data &&
            (s->s3.total_renegotiations != 0) &&
            ossl_statem_app_data_allowed(s)) {
            s->s3.in_read_app_data = 2;
            return -1;
        } else {
            SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                     SSL_R_UNEXPECTED_RECORD);
            return -1;
        }
    }
    /* not reached */
}
Beispiel #2
0
const char *SSL_state_string_long(const SSL *s)
{
    if (ossl_statem_in_error(s))
        return "error";

    switch (SSL_get_state(s)) {
    case TLS_ST_BEFORE:
        return "before SSL initialization";
    case TLS_ST_OK:
        return "SSL negotiation finished successfully";
    case TLS_ST_CW_CLNT_HELLO:
        return "SSLv3/TLS write client hello";
    case TLS_ST_CR_SRVR_HELLO:
        return "SSLv3/TLS read server hello";
    case TLS_ST_CR_CERT:
        return "SSLv3/TLS read server certificate";
    case TLS_ST_CR_KEY_EXCH:
        return "SSLv3/TLS read server key exchange";
    case TLS_ST_CR_CERT_REQ:
        return "SSLv3/TLS read server certificate request";
    case TLS_ST_CR_SESSION_TICKET:
        return "SSLv3/TLS read server session ticket";
    case TLS_ST_CR_SRVR_DONE:
        return "SSLv3/TLS read server done";
    case TLS_ST_CW_CERT:
        return "SSLv3/TLS write client certificate";
    case TLS_ST_CW_KEY_EXCH:
        return "SSLv3/TLS write client key exchange";
    case TLS_ST_CW_CERT_VRFY:
        return "SSLv3/TLS write certificate verify";
    case TLS_ST_CW_CHANGE:
    case TLS_ST_SW_CHANGE:
        return "SSLv3/TLS write change cipher spec";
    case TLS_ST_CW_FINISHED:
    case TLS_ST_SW_FINISHED:
        return "SSLv3/TLS write finished";
    case TLS_ST_CR_CHANGE:
    case TLS_ST_SR_CHANGE:
        return "SSLv3/TLS read change cipher spec";
    case TLS_ST_CR_FINISHED:
    case TLS_ST_SR_FINISHED:
        return "SSLv3/TLS read finished";
    case TLS_ST_SR_CLNT_HELLO:
        return "SSLv3/TLS read client hello";
    case TLS_ST_SW_HELLO_REQ:
        return "SSLv3/TLS write hello request";
    case TLS_ST_SW_SRVR_HELLO:
        return "SSLv3/TLS write server hello";
    case TLS_ST_SW_CERT:
        return "SSLv3/TLS write certificate";
    case TLS_ST_SW_KEY_EXCH:
        return "SSLv3/TLS write key exchange";
    case TLS_ST_SW_CERT_REQ:
        return "SSLv3/TLS write certificate request";
    case TLS_ST_SW_SESSION_TICKET:
        return "SSLv3/TLS write session ticket";
    case TLS_ST_SW_SRVR_DONE:
        return "SSLv3/TLS write server done";
    case TLS_ST_SR_CERT:
        return "SSLv3/TLS read client certificate";
    case TLS_ST_SR_KEY_EXCH:
        return "SSLv3/TLS read client key exchange";
    case TLS_ST_SR_CERT_VRFY:
        return "SSLv3/TLS read certificate verify";
    case DTLS_ST_CR_HELLO_VERIFY_REQUEST:
        return "DTLS1 read hello verify request";
    case DTLS_ST_SW_HELLO_VERIFY_REQUEST:
        return "DTLS1 write hello verify request";
    default:
        return "unknown state";
    }
}
Beispiel #3
0
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;
}
Beispiel #4
0
const char *SSL_state_string(const SSL *s)
{
    if (ossl_statem_in_error(s))
        return "SSLERR";

    switch (SSL_get_state(s)) {
    case TLS_ST_BEFORE:
        return "PINIT ";
    case TLS_ST_OK:
        return "SSLOK ";
    case TLS_ST_CW_CLNT_HELLO:
        return "TWCH";
    case TLS_ST_CR_SRVR_HELLO:
        return "TRSH";
    case TLS_ST_CR_CERT:
        return "TRSC";
    case TLS_ST_CR_KEY_EXCH:
        return "TRSKE";
    case TLS_ST_CR_CERT_REQ:
        return "TRCR";
    case TLS_ST_CR_SRVR_DONE:
        return "TRSD";
    case TLS_ST_CW_CERT:
        return "TWCC";
    case TLS_ST_CW_KEY_EXCH:
        return "TWCKE";
    case TLS_ST_CW_CERT_VRFY:
        return "TWCV";
    case TLS_ST_SW_CHANGE:
    case TLS_ST_CW_CHANGE:
        return "TWCCS";
    case TLS_ST_SW_FINISHED:
    case TLS_ST_CW_FINISHED:
        return "TWFIN";
    case TLS_ST_SR_CHANGE:
    case TLS_ST_CR_CHANGE:
        return "TRCCS";
    case TLS_ST_SR_FINISHED:
    case TLS_ST_CR_FINISHED:
        return "TRFIN";
    case TLS_ST_SW_HELLO_REQ:
        return "TWHR";
    case TLS_ST_SR_CLNT_HELLO:
        return "TRCH";
    case TLS_ST_SW_SRVR_HELLO:
        return "TWSH";
    case TLS_ST_SW_CERT:
        return "TWSC";
    case TLS_ST_SW_KEY_EXCH:
        return "TWSKE";
    case TLS_ST_SW_CERT_REQ:
        return "TWCR";
    case TLS_ST_SW_SRVR_DONE:
        return "TWSD";
    case TLS_ST_SR_CERT:
        return "TRCC";
    case TLS_ST_SR_KEY_EXCH:
        return "TRCKE";
    case TLS_ST_SR_CERT_VRFY:
        return "TRCV";
    case DTLS_ST_CR_HELLO_VERIFY_REQUEST:
        return "DRCHV";
    case DTLS_ST_SW_HELLO_VERIFY_REQUEST:
        return "DWCHV";
    default:
        return "UNKWN ";
    }
}