/* $OpenBSD: d1_pkt.c,v 1.123 2022/03/26 15:05:53 jsing 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 <endian.h>
#include <errno.h>
#include <stdio.h>

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

#include "bytestring.h"
#include "dtls_locl.h"
#include "pqueue.h"
#include "ssl_locl.h"

/* 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 dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap,
    const unsigned char *seq);
static void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap,
    const unsigned char *seq);
static DTLS1_BITMAP *dtls1_get_bitmap(SSL *s, SSL3_RECORD_INTERNAL *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, DTLS1_RECORD_DATA_INTERNAL *rdata)
{
        ssl3_release_buffer(&s->s3->rbuf);

        s->internal->packet = rdata->packet;
        s->internal->packet_length = rdata->packet_length;
        memcpy(&(s->s3->rbuf), &(rdata->rbuf), sizeof(SSL3_BUFFER_INTERNAL));
        memcpy(&(s->s3->rrec), &(rdata->rrec), sizeof(SSL3_RECORD_INTERNAL));

        return (1);
}

static int
dtls1_buffer_record(SSL *s, record_pqueue *queue, unsigned char *priority)
{
        DTLS1_RECORD_DATA_INTERNAL *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_INTERNAL));
        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_INTERNAL));
        memcpy(&(rdata->rrec), &(s->s3->rrec), sizeof(SSL3_RECORD_INTERNAL));

        item->data = rdata;

        s->internal->packet = NULL;
        s->internal->packet_length = 0;
        memset(&(s->s3->rbuf), 0, sizeof(SSL3_BUFFER_INTERNAL));
        memset(&(s->s3->rrec), 0, sizeof(SSL3_RECORD_INTERNAL));

        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:
        ssl3_release_buffer(&rdata->rbuf);

 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->data);

                free(item->data);
                pitem_free(item);

                return (1);
        }

        return (0);
}

static int
dtls1_process_buffered_record(SSL *s)
{
        /* Check if epoch is current. */
        if (s->d1->unprocessed_rcds.epoch !=
            tls12_record_layer_read_epoch(s->internal->rl))
                return (0);

        /* Update epoch once all unprocessed records have been processed. */
        if (pqueue_peek(s->d1->unprocessed_rcds.q) == NULL) {
                s->d1->unprocessed_rcds.epoch =
                    tls12_record_layer_read_epoch(s->internal->rl) + 1;
                return (0);
        }

        /* Process one of the records. */
        if (!dtls1_retrieve_buffered_record(s, &s->d1->unprocessed_rcds))
                return (-1);
        if (!dtls1_process_record(s))
                return (-1);

        return (1);
}

static int
dtls1_process_record(SSL *s)
{
        SSL3_RECORD_INTERNAL *rr = &(s->s3->rrec);
        uint8_t alert_desc;
        uint8_t *out;
        size_t out_len;

        tls12_record_layer_set_version(s->internal->rl, s->version);

        if (!tls12_record_layer_open_record(s->internal->rl, s->internal->packet,
            s->internal->packet_length, &out, &out_len)) {
                tls12_record_layer_alert(s->internal->rl, &alert_desc);

                if (alert_desc == 0)
                        goto err;

                /*
                 * DTLS should silently discard invalid records, including those
                 * with a bad MAC, as per RFC 6347 section 4.1.2.1.
                 */
                if (alert_desc == SSL_AD_BAD_RECORD_MAC) {
                        out_len = 0;
                        goto done;
                }

                if (alert_desc == SSL_AD_RECORD_OVERFLOW)
                        SSLerror(s, SSL_R_ENCRYPTED_LENGTH_TOO_LONG);

                goto fatal_err;
        }

 done:
        rr->data = out;
        rr->length = out_len;
        rr->off = 0;

        s->internal->packet_length = 0;

        return (1);

 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, alert_desc);
 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_INTERNAL *rr = &(s->s3->rrec);
        unsigned char *p = NULL;
        DTLS1_BITMAP *bitmap;
        unsigned int is_next_epoch;
        int ret, n;

        /* See if there are pending records that can now be processed. */
        if ((ret = dtls1_process_buffered_record(s)) != 0)
                return (ret);

        /* 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_bytes(&header, &seq_no, SSL3_SEQUENCE_SIZE))
                        goto again;
                if (!CBS_get_u16(&seq_no, &epoch))
                        goto again;
                if (!CBS_write_bytes(&seq_no, &rr->seq_num[2],
                    sizeof(rr->seq_num) - 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 (!(s->d1->listen && rr->type == SSL3_RT_HANDSHAKE &&
            p != NULL && *p == SSL3_MT_CLIENT_HELLO) &&
            !dtls1_record_replay_check(s, bitmap, rr->seq_num))
                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) && !s->d1->listen) {
                        if (dtls1_buffer_record(s, &(s->d1->unprocessed_rcds),
                            rr->seq_num) < 0)
                                return (-1);
                        /* Mark receipt of record. */
                        dtls1_record_bitmap_update(s, bitmap, rr->seq_num);
                }
                goto again;
        }

        if (!dtls1_process_record(s))
                goto again;

        /* Mark receipt of record. */
        dtls1_record_bitmap_update(s, bitmap, rr->seq_num);

        return (1);
}

static int
dtls1_read_handshake_unexpected(SSL *s)
{
        SSL3_RECORD_INTERNAL *rr = &s->s3->rrec;
        struct hm_header_st hs_msg_hdr;
        CBS cbs;
        int ret;

        if (s->internal->in_handshake) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                return -1;
        }

        if (rr->off != 0) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                return -1;
        }

        /* Parse handshake message header. */
        CBS_init(&cbs, rr->data, rr->length);
        if (!dtls1_get_message_header(&cbs, &hs_msg_hdr))
                return -1; /* XXX - probably should drop/continue. */

        /* This may just be a stale retransmit. */
        if (rr->epoch != tls12_record_layer_read_epoch(s->internal->rl)) {
                rr->length = 0;
                return 1;
        }

        if (hs_msg_hdr.type == SSL3_MT_HELLO_REQUEST) {
                /*
                 * Incoming HelloRequest messages should only be received by a
                 * client. A server may send these at any time - a client should
                 * ignore the message if received in the middle of a handshake.
                 * See RFC 5246 sections 7.4 and 7.4.1.1.
                 */
                if (s->server) {
                        SSLerror(s, SSL_R_UNEXPECTED_MESSAGE);
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                             SSL_AD_UNEXPECTED_MESSAGE);
                        return -1;
                }

                /* XXX - should also check frag offset/length. */
                if (hs_msg_hdr.msg_len != 0) {
                        SSLerror(s, SSL_R_BAD_HELLO_REQUEST);
                        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                        return -1;
                }

                ssl_msg_callback(s, 0, SSL3_RT_HANDSHAKE, rr->data,
                    DTLS1_HM_HEADER_LENGTH);

                rr->length = 0;

                /*
                 * It should be impossible to hit this, but keep the safety
                 * harness for now...
                 */
                if (s->session == NULL || s->session->cipher == NULL)
                        return 1;

                /*
                 * Ignore this message if we're currently handshaking,
                 * renegotiation is already pending or renegotiation is disabled
                 * via flags.
                 */
                if (!SSL_is_init_finished(s) || s->s3->renegotiate ||
                    (s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS) != 0)
                        return 1;

                s->d1->handshake_read_seq++;

                /* XXX - why is this set here but not in ssl3? */
                s->internal->new_session = 1;

                if (!ssl3_renegotiate(s))
                        return 1;
                if (!ssl3_renegotiate_check(s))
                        return 1;

        } else if (hs_msg_hdr.type == SSL3_MT_CLIENT_HELLO) {
                /*
                 * Incoming ClientHello messages should only be received by a
                 * server. A client may send these in response to server
                 * initiated renegotiation (HelloRequest) or in order to
                 * initiate renegotiation by the client. See RFC 5246 section
                 * 7.4.1.2.
                 */
                if (!s->server) {
                        SSLerror(s, SSL_R_UNEXPECTED_MESSAGE);
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                             SSL_AD_UNEXPECTED_MESSAGE);
                        return -1;
                }

                /*
                 * A client should not be sending a ClientHello unless we're not
                 * currently handshaking.
                 */
                if (!SSL_is_init_finished(s)) {
                        SSLerror(s, SSL_R_UNEXPECTED_MESSAGE);
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_UNEXPECTED_MESSAGE);
                        return -1;
                }

                if ((s->internal->options & SSL_OP_NO_CLIENT_RENEGOTIATION) != 0) {
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_NO_RENEGOTIATION);
                        return -1;
                }

                if (s->session == NULL || s->session->cipher == NULL) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        return -1;
                }

                /* Client requested renegotiation but it is not permitted. */
                if (!s->s3->send_connection_binding ||
                    (s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS) != 0) {
                        ssl3_send_alert(s, SSL3_AL_WARNING,
                            SSL_AD_NO_RENEGOTIATION);
                        return 1;
                }

                s->s3->hs.state = SSL_ST_ACCEPT;
                s->internal->renegotiate = 1;
                s->internal->new_session = 1;

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

                /* XXX - should this be calling ssl_msg_callback()? */

                dtls1_retransmit_buffered_messages(s);

                rr->length = 0;

                return 1;

        } else {
                SSLerror(s, SSL_R_UNEXPECTED_MESSAGE);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
                return -1;
        }

        if ((ret = s->internal->handshake_func(s)) < 0)
                return ret;
        if (ret == 0) {
                SSLerror(s, SSL_R_SSL_HANDSHAKE_FAILURE);
                return -1;
        }

        if (!(s->internal->mode & SSL_MODE_AUTO_RETRY)) {
                if (s->s3->rbuf.left == 0) {
                        ssl_force_want_read(s);
                        return -1;
                }
        }

        /*
         * We either finished a handshake or ignored the request, now try again
         * to obtain the (application) data we were asked for.
         */
        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)
{
        SSL3_RECORD_INTERNAL *rr;
        int rrcount = 0;
        unsigned int n;
        int ret;

        if (s->s3->rbuf.buf == NULL) {
                if (!ssl3_setup_buffers(s))
                        return -1;
        }

        if (len < 0) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                return -1;
        }

        if (type != 0 && type != SSL3_RT_APPLICATION_DATA &&
            type != SSL3_RT_HANDSHAKE) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                return -1;
        }
        if (peek && type != SSL3_RT_APPLICATION_DATA) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                return -1;
        }

        if (SSL_in_init(s) && !s->internal->in_handshake) {
                if ((ret = s->internal->handshake_func(s)) < 0)
                        return ret;
                if (ret == 0) {
                        SSLerror(s, SSL_R_SSL_HANDSHAKE_FAILURE);
                        return -1;
                }
        }

 start:
        /*
         * Do not process more than three consecutive records, otherwise the
         * peer can cause us to loop indefinitely. Instead, return with an
         * SSL_ERROR_WANT_READ so the caller can choose when to handle further
         * processing. In the future, the total number of non-handshake and
         * non-application data records per connection should probably also be
         * limited...
         */
        if (rrcount++ >= 3) {
                ssl_force_want_read(s);
                return -1;
        }

        s->internal->rwstate = SSL_NOTHING;

        rr = &s->s3->rrec;

        /*
         * We are not handshaking and have no data yet, so process data buffered
         * during the last handshake in advance, if any.
         */
        if (s->s3->hs.state == SSL_ST_OK && rr->length == 0)
                dtls1_retrieve_buffered_record(s, &s->d1->buffered_app_data);

        if (dtls1_handle_timeout(s) > 0)
                goto start;

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

        if (s->d1->listen && rr->type != SSL3_RT_HANDSHAKE) {
                rr->length = 0;
                goto start;
        }

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

        if (s->s3->change_cipher_spec && 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, &s->d1->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) {
                s->internal->rwstate = SSL_NOTHING;
                rr->length = 0;
                return 0;
        }

        /* SSL3_RT_APPLICATION_DATA or SSL3_RT_HANDSHAKE */
        if (type == rr->type) {
                /*
                 * 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 &&
                    !tls12_record_layer_read_protected(s->internal->rl)) {
                        SSLerror(s, SSL_R_APP_DATA_IN_HANDSHAKE);
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_UNEXPECTED_MESSAGE);
                        return -1;
                }

                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) {
                        memset(&rr->data[rr->off], 0, n);
                        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).
         */

        if (rr->type == SSL3_RT_ALERT) {
                if ((ret = ssl3_read_alert(s)) <= 0)
                        return ret;
                goto start;
        }

        if (s->internal->shutdown & SSL_SENT_SHUTDOWN) {
                s->internal->rwstate = SSL_NOTHING;
                rr->length = 0;
                return (0);
        }

        if (rr->type == 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 != 0 &&
                    s->s3->total_renegotiations != 0 &&
                    (((s->s3->hs.state & SSL_ST_CONNECT) &&
                    (s->s3->hs.state >= SSL3_ST_CW_CLNT_HELLO_A) &&
                    (s->s3->hs.state <= SSL3_ST_CR_SRVR_HELLO_A)) || (
                    (s->s3->hs.state & SSL_ST_ACCEPT) &&
                    (s->s3->hs.state <= SSL3_ST_SW_HELLO_REQ_A) &&
                    (s->s3->hs.state >= SSL3_ST_SR_CLNT_HELLO_A)))) {
                        s->s3->in_read_app_data = 2;
                        return -1;
                } else {
                        SSLerror(s, SSL_R_UNEXPECTED_RECORD);
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_UNEXPECTED_MESSAGE);
                        return -1;
                }
        }

        if (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC) {
                if ((ret = ssl3_read_change_cipher_spec(s)) <= 0)
                        return ret;
                goto start;
        }

        if (rr->type == SSL3_RT_HANDSHAKE) {
                if ((ret = dtls1_read_handshake_unexpected(s)) <= 0)
                        return ret;
                goto start;
        }

        /* Unknown record type. */
        SSLerror(s, SSL_R_UNEXPECTED_RECORD);
        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
        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;
}

/* 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)
{
        SSL3_BUFFER_INTERNAL *wb = &(s->s3->wbuf);
        size_t out_len;
        CBB cbb;
        int ret;

        memset(&cbb, 0, sizeof(cbb));

        /*
         * First check if there is a SSL3_BUFFER_INTERNAL still being written
         * out.  This will happen with non blocking IO.
         */
        if (wb->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, let's send it */
        if (s->s3->alert_dispatch) {
                if ((ret = ssl3_dispatch_alert(s)) <= 0)
                        return (ret);
                /* If it went, fall through and send more stuff. */
        }

        if (len == 0)
                return 0;

        wb->offset = 0;

        if (!CBB_init_fixed(&cbb, wb->buf, wb->len))
                goto err;

        tls12_record_layer_set_version(s->internal->rl, s->version);

        if (!tls12_record_layer_seal_record(s->internal->rl, type, buf, len, &cbb))
                goto err;

        if (!CBB_finish(&cbb, NULL, &out_len))
                goto err;

        wb->left = out_len;

        /*
         * Memorize arguments so that ssl3_write_pending can detect
         * bad write retries later.
         */
        s->s3->wpend_tot = len;
        s->s3->wpend_buf = buf;
        s->s3->wpend_type = type;
        s->s3->wpend_ret = len;

        /* We now just need to write the buffer. */
        return ssl3_write_pending(s, type, buf, len);

 err:
        CBB_cleanup(&cbb);

        return -1;
}

static int
dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap,
    const unsigned char *seq)
{
        unsigned int shift;
        int cmp;

        cmp = satsub64be(seq, bitmap->max_seq_num);
        if (cmp > 0)
                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 */

        return 1;
}

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

        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;
        }
}

static DTLS1_BITMAP *
dtls1_get_bitmap(SSL *s, SSL3_RECORD_INTERNAL *rr, unsigned int *is_next_epoch)
{
        uint16_t read_epoch, read_epoch_next;

        *is_next_epoch = 0;

        read_epoch = tls12_record_layer_read_epoch(s->internal->rl);
        read_epoch_next = read_epoch + 1;

        /* In current epoch, accept HM, CCS, DATA, & ALERT */
        if (rr->epoch == read_epoch)
                return &s->d1->bitmap;

        /* Only HM and ALERT messages can be from the next epoch */
        if (rr->epoch == read_epoch_next &&
            (rr->type == SSL3_RT_HANDSHAKE || rr->type == SSL3_RT_ALERT)) {
                *is_next_epoch = 1;
                return &s->d1->next_bitmap;
        }

        return NULL;
}

void
dtls1_reset_read_seq_numbers(SSL *s)
{
        memcpy(&(s->d1->bitmap), &(s->d1->next_bitmap), sizeof(DTLS1_BITMAP));
        memset(&(s->d1->next_bitmap), 0, sizeof(DTLS1_BITMAP));
}