/* $OpenBSD: ssl_pkt.c,v 1.60 2022/09/11 13:51:25 jsing Exp $ */
/* 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.]
 */
/* ====================================================================
 * Copyright (c) 1998-2002 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).
 *
 */

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

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

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

static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
    unsigned int len);
static int ssl3_get_record(SSL *s);

/*
 * Force a WANT_READ return for certain error conditions where
 * we don't want to spin internally.
 */
void
ssl_force_want_read(SSL *s)
{
        BIO *bio;

        bio = SSL_get_rbio(s);
        BIO_clear_retry_flags(bio);
        BIO_set_retry_read(bio);

        s->internal->rwstate = SSL_READING;
}

/*
 * If extend == 0, obtain new n-byte packet; if extend == 1, increase
 * packet by another n bytes.
 * The packet will be in the sub-array of s->s3->rbuf.buf specified
 * by s->internal->packet and s->internal->packet_length.
 * (If s->internal->read_ahead is set, 'max' bytes may be stored in rbuf
 * [plus s->internal->packet_length bytes if extend == 1].)
 */
static int
ssl3_read_n(SSL *s, int n, int max, int extend)
{
        SSL3_BUFFER_INTERNAL *rb = &(s->s3->rbuf);
        int i, len, left;
        size_t align;
        unsigned char *pkt;

        if (n <= 0)
                return n;

        if (rb->buf == NULL)
                if (!ssl3_setup_read_buffer(s))
                        return -1;

        left = rb->left;
        align = (size_t)rb->buf + SSL3_RT_HEADER_LENGTH;
        align = (-align) & (SSL3_ALIGN_PAYLOAD - 1);

        if (!extend) {
                /* start with empty packet ... */
                if (left == 0)
                        rb->offset = align;
                else if (align != 0 && left >= SSL3_RT_HEADER_LENGTH) {
                        /* check if next packet length is large
                         * enough to justify payload alignment... */
                        pkt = rb->buf + rb->offset;
                        if (pkt[0] == SSL3_RT_APPLICATION_DATA &&
                            (pkt[3]<<8|pkt[4]) >= 128) {
                                /* Note that even if packet is corrupted
                                 * and its length field is insane, we can
                                 * only be led to wrong decision about
                                 * whether memmove will occur or not.
                                 * Header values has no effect on memmove
                                 * arguments and therefore no buffer
                                 * overrun can be triggered. */
                                memmove(rb->buf + align, pkt, left);
                                rb->offset = align;
                        }
                }
                s->internal->packet = rb->buf + rb->offset;
                s->internal->packet_length = 0;
                /* ... now we can act as if 'extend' was set */
        }

        /* For DTLS/UDP reads should not span multiple packets
         * because the read operation returns the whole packet
         * at once (as long as it fits into the buffer). */
        if (SSL_is_dtls(s)) {
                if (left > 0 && n > left)
                        n = left;
        }

        /* if there is enough in the buffer from a previous read, take some */
        if (left >= n) {
                s->internal->packet_length += n;
                rb->left = left - n;
                rb->offset += n;
                return (n);
        }

        /* else we need to read more data */

        len = s->internal->packet_length;
        pkt = rb->buf + align;
        /* Move any available bytes to front of buffer:
         * 'len' bytes already pointed to by 'packet',
         * 'left' extra ones at the end */
        if (s->internal->packet != pkt)  {
                /* len > 0 */
                memmove(pkt, s->internal->packet, len + left);
                s->internal->packet = pkt;
                rb->offset = len + align;
        }

        if (n > (int)(rb->len - rb->offset)) {
                /* does not happen */
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                return -1;
        }

        if (s->internal->read_ahead || SSL_is_dtls(s)) {
                if (max < n)
                        max = n;
                if (max > (int)(rb->len - rb->offset))
                        max = rb->len - rb->offset;
        } else {
                /* ignore max parameter */
                max = n;
        }

        while (left < n) {
                /* Now we have len+left bytes at the front of s->s3->rbuf.buf
                 * and need to read in more until we have len+n (up to
                 * len+max if possible) */

                errno = 0;
                if (s->rbio != NULL) {
                        s->internal->rwstate = SSL_READING;
                        i = BIO_read(s->rbio, pkt + len + left, max - left);
                } else {
                        SSLerror(s, SSL_R_READ_BIO_NOT_SET);
                        i = -1;
                }

                if (i <= 0) {
                        rb->left = left;
                        if (s->internal->mode & SSL_MODE_RELEASE_BUFFERS &&
                            !SSL_is_dtls(s)) {
                                if (len + left == 0)
                                        ssl3_release_read_buffer(s);
                        }
                        return (i);
                }
                left += i;

                /*
                 * reads should *never* span multiple packets for DTLS because
                 * the underlying transport protocol is message oriented as
                 * opposed to byte oriented as in the TLS case.
                 */
                if (SSL_is_dtls(s)) {
                        if (n > left)
                                n = left; /* makes the while condition false */
                }
        }

        /* done reading, now the book-keeping */
        rb->offset += n;
        rb->left = left - n;
        s->internal->packet_length += n;
        s->internal->rwstate = SSL_NOTHING;

        return (n);
}

int
ssl3_packet_read(SSL *s, int plen)
{
        int n;

        n = ssl3_read_n(s, plen, s->s3->rbuf.len, 0);
        if (n <= 0)
                return n;
        if (s->internal->packet_length < plen)
                return s->internal->packet_length;

        return plen;
}

int
ssl3_packet_extend(SSL *s, int plen)
{
        int rlen, n;

        if (s->internal->packet_length >= plen)
                return plen;
        rlen = plen - s->internal->packet_length;

        n = ssl3_read_n(s, rlen, rlen, 1);
        if (n <= 0)
                return n;
        if (s->internal->packet_length < plen)
                return s->internal->packet_length;

        return plen;
}

/* 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 ssl3_read_bytes */
static int
ssl3_get_record(SSL *s)
{
        SSL3_BUFFER_INTERNAL *rb = &(s->s3->rbuf);
        SSL3_RECORD_INTERNAL *rr = &(s->s3->rrec);
        uint8_t alert_desc;
        uint8_t *out;
        size_t out_len;
        int al, n;
        int ret = -1;

 again:
        /* check if we have the header */
        if ((s->internal->rstate != SSL_ST_READ_BODY) ||
            (s->internal->packet_length < SSL3_RT_HEADER_LENGTH)) {
                CBS header;
                uint16_t len, ssl_version;
                uint8_t type;

                n = ssl3_packet_read(s, SSL3_RT_HEADER_LENGTH);
                if (n <= 0)
                        return (n);

                s->internal->mac_packet = 1;
                s->internal->rstate = SSL_ST_READ_BODY;

                if (s->server && s->internal->first_packet) {
                        if ((ret = ssl_server_legacy_first_packet(s)) != 1)
                                return (ret);
                        ret = -1;
                }

                CBS_init(&header, s->internal->packet, SSL3_RT_HEADER_LENGTH);

                /* Pull apart the header into the SSL3_RECORD_INTERNAL */
                if (!CBS_get_u8(&header, &type) ||
                    !CBS_get_u16(&header, &ssl_version) ||
                    !CBS_get_u16(&header, &len)) {
                        SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
                        goto err;
                }

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

                /* Lets check version */
                if (!s->internal->first_packet && ssl_version != s->version) {
                        if ((s->version & 0xFF00) == (ssl_version & 0xFF00) &&
                            !tls12_record_layer_write_protected(s->internal->rl)) {
                                /* Send back error using their minor version number :-) */
                                s->version = ssl_version;
                        }
                        SSLerror(s, SSL_R_WRONG_VERSION_NUMBER);
                        al = SSL_AD_PROTOCOL_VERSION;
                        goto fatal_err;
                }

                if ((ssl_version >> 8) != SSL3_VERSION_MAJOR) {
                        SSLerror(s, SSL_R_WRONG_VERSION_NUMBER);
                        goto err;
                }

                if (rr->length > rb->len - SSL3_RT_HEADER_LENGTH) {
                        al = SSL_AD_RECORD_OVERFLOW;
                        SSLerror(s, SSL_R_PACKET_LENGTH_TOO_LONG);
                        goto fatal_err;
                }
        }

        n = ssl3_packet_extend(s, SSL3_RT_HEADER_LENGTH + rr->length);
        if (n <= 0)
                return (n);
        if (n != SSL3_RT_HEADER_LENGTH + rr->length)
                return (n);

        s->internal->rstate = SSL_ST_READ_HEADER; /* set state for later operations */

        /*
         * A full record has now been read from the wire, which now needs
         * to be processed.
         */
        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;

                if (alert_desc == SSL_AD_RECORD_OVERFLOW)
                        SSLerror(s, SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
                else if (alert_desc == SSL_AD_BAD_RECORD_MAC)
                        SSLerror(s, SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);

                al = alert_desc;
                goto fatal_err;
        }

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

        /* we have pulled in a full packet so zero things */
        s->internal->packet_length = 0;

        if (rr->length == 0) {
                /*
                 * Zero-length fragments are only permitted for application
                 * data, as per RFC 5246 section 6.2.1.
                 */
                if (rr->type != SSL3_RT_APPLICATION_DATA) {
                        SSLerror(s, SSL_R_BAD_LENGTH);
                        al = SSL_AD_UNEXPECTED_MESSAGE;
                        goto fatal_err;
                }

                /*
                 * CBC countermeasures for known IV weaknesses can legitimately
                 * insert a single empty record, so we allow ourselves to read
                 * once past a single empty record without forcing want_read.
                 */
                if (s->internal->empty_record_count++ > SSL_MAX_EMPTY_RECORDS) {
                        SSLerror(s, SSL_R_PEER_BEHAVING_BADLY);
                        return -1;
                }
                if (s->internal->empty_record_count > 1) {
                        ssl_force_want_read(s);
                        return -1;
                }
                goto again;
        }

        s->internal->empty_record_count = 0;

        return (1);

 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
 err:
        return (ret);
}

/* 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
ssl3_write_bytes(SSL *s, int type, const void *buf_, int len)
{
        const unsigned char *buf = buf_;
        unsigned int tot, n, nw;
        int i;

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

        s->internal->rwstate = SSL_NOTHING;
        tot = s->s3->wnum;
        s->s3->wnum = 0;

        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 < tot)
                len = tot;
        n = (len - tot);
        for (;;) {
                if (n > s->max_send_fragment)
                        nw = s->max_send_fragment;
                else
                        nw = n;

                i = do_ssl3_write(s, type, &(buf[tot]), nw);
                if (i <= 0) {
                        s->s3->wnum = tot;
                        return i;
                }

                if ((i == (int)n) || (type == SSL3_RT_APPLICATION_DATA &&
                    (s->internal->mode & SSL_MODE_ENABLE_PARTIAL_WRITE))) {
                        /*
                         * Next chunk of data should get another prepended
                         * empty fragment in ciphersuites with known-IV
                         * weakness.
                         */
                        s->s3->empty_fragment_done = 0;

                        return tot + i;
                }

                n -= i;
                tot += i;
        }
}

static int
do_ssl3_write(SSL *s, int type, const unsigned char *buf, unsigned int len)
{
        SSL3_BUFFER_INTERNAL *wb = &(s->s3->wbuf);
        SSL_SESSION *sess = s->session;
        int need_empty_fragment = 0;
        size_t align, out_len;
        uint16_t version;
        CBB cbb;
        int ret;

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

        if (wb->buf == NULL)
                if (!ssl3_setup_write_buffer(s))
                        return -1;

        /*
         * First check if there is a SSL3_BUFFER_INTERNAL still being written
         * out.  This will happen with non blocking IO.
         */
        if (wb->left != 0)
                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. */

                /* We may have released our buffer, if so get it again. */
                if (wb->buf == NULL)
                        if (!ssl3_setup_write_buffer(s))
                                return -1;
        }

        if (len == 0)
                return 0;

        /*
         * Some servers hang if initial client hello is larger than 256
         * bytes and record version number > TLS 1.0.
         */
        version = s->version;
        if (s->s3->hs.state == SSL3_ST_CW_CLNT_HELLO_B &&
            !s->internal->renegotiate &&
            s->s3->hs.our_max_tls_version > TLS1_VERSION)
                version = TLS1_VERSION;

        /*
         * Countermeasure against known-IV weakness in CBC ciphersuites
         * (see http://www.openssl.org/~bodo/tls-cbc.txt). Note that this
         * is unnecessary for AEAD.
         */
        if (sess != NULL && tls12_record_layer_write_protected(s->internal->rl)) {
                if (s->s3->need_empty_fragments &&
                    !s->s3->empty_fragment_done &&
                    type == SSL3_RT_APPLICATION_DATA)
                        need_empty_fragment = 1;
        }

        /*
         * An extra fragment would be a couple of cipher blocks, which would
         * be a multiple of SSL3_ALIGN_PAYLOAD, so if we want to align the real
         * payload, then we can just simply pretend we have two headers.
         */
        align = (size_t)wb->buf + SSL3_RT_HEADER_LENGTH;
        if (need_empty_fragment)
                align += SSL3_RT_HEADER_LENGTH;
        align = (-align) & (SSL3_ALIGN_PAYLOAD - 1);
        wb->offset = align;

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

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

        if (need_empty_fragment) {
                if (!tls12_record_layer_seal_record(s->internal->rl, type,
                    buf, 0, &cbb))
                        goto err;
                s->s3->empty_fragment_done = 1;
        }

        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;
}

/* if s->s3->wbuf.left != 0, we need to call this */
int
ssl3_write_pending(SSL *s, int type, const unsigned char *buf, unsigned int len)
{
        int i;
        SSL3_BUFFER_INTERNAL *wb = &(s->s3->wbuf);

        /* XXXX */
        if ((s->s3->wpend_tot > (int)len) || ((s->s3->wpend_buf != buf) &&
            !(s->internal->mode & SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER)) ||
            (s->s3->wpend_type != type)) {
                SSLerror(s, SSL_R_BAD_WRITE_RETRY);
                return (-1);
        }

        for (;;) {
                errno = 0;
                if (s->wbio != NULL) {
                        s->internal->rwstate = SSL_WRITING;
                        i = BIO_write(s->wbio, (char *)&(wb->buf[wb->offset]),
                            (unsigned int)wb->left);
                } else {
                        SSLerror(s, SSL_R_BIO_NOT_SET);
                        i = -1;
                }
                if (i == wb->left) {
                        wb->left = 0;
                        wb->offset += i;
                        if (s->internal->mode & SSL_MODE_RELEASE_BUFFERS &&
                            !SSL_is_dtls(s))
                                ssl3_release_write_buffer(s);
                        s->internal->rwstate = SSL_NOTHING;
                        return (s->s3->wpend_ret);
                } else if (i <= 0) {
                        /*
                         * For DTLS, just drop it. That's kind of the
                         * whole point in using a datagram service.
                         */
                        if (SSL_is_dtls(s))
                                wb->left = 0;
                        return (i);
                }
                wb->offset += i;
                wb->left -= i;
        }
}

int
ssl3_read_alert(SSL *s)
{
        SSL3_RECORD_INTERNAL *rr = &s->s3->rrec;
        uint8_t alert_level, alert_descr;
        CBS cbs;

        /*
         * TLSv1.2 permits an alert to be fragmented across multiple records or
         * for multiple alerts to be be coalesced into a single alert record.
         * In the case of DTLS, there is no way to reassemble an alert
         * fragmented across multiple records, hence a full alert must be
         * available in the record.
         */
        while (rr->length > 0 &&
            s->s3->alert_fragment_len < sizeof(s->s3->alert_fragment)) {
                s->s3->alert_fragment[s->s3->alert_fragment_len++] =
                    rr->data[rr->off++];
                rr->length--;
        }
        if (s->s3->alert_fragment_len < sizeof(s->s3->alert_fragment)) {
                if (SSL_is_dtls(s)) {
                        SSLerror(s, SSL_R_BAD_LENGTH);
                        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                        return -1;
                }
                return 1;
        }

        CBS_init(&cbs, s->s3->alert_fragment, sizeof(s->s3->alert_fragment));

        ssl_msg_callback_cbs(s, 0, SSL3_RT_ALERT, &cbs);

        if (!CBS_get_u8(&cbs, &alert_level))
                return -1;
        if (!CBS_get_u8(&cbs, &alert_descr))
                return -1;

        s->s3->alert_fragment_len = 0;

        ssl_info_callback(s, SSL_CB_READ_ALERT,
            (alert_level << 8) | alert_descr);

        if (alert_level == SSL3_AL_WARNING) {
                s->s3->warn_alert = alert_descr;
                if (alert_descr == SSL_AD_CLOSE_NOTIFY) {
                        s->internal->shutdown |= SSL_RECEIVED_SHUTDOWN;
                        return 0;
                }
                /* We requested renegotiation and the peer rejected it. */
                if (alert_descr == SSL_AD_NO_RENEGOTIATION) {
                        SSLerror(s, SSL_R_NO_RENEGOTIATION);
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_HANDSHAKE_FAILURE);
                        return -1;
                }
        } else if (alert_level == SSL3_AL_FATAL) {
                s->internal->rwstate = SSL_NOTHING;
                s->s3->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 {
                SSLerror(s, SSL_R_UNKNOWN_ALERT_TYPE);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
                return -1;
        }

        return 1;
}

int
ssl3_read_change_cipher_spec(SSL *s)
{
        SSL3_RECORD_INTERNAL *rr = &s->s3->rrec;
        const uint8_t ccs[] = { SSL3_MT_CCS };
        CBS cbs;

        /*
         * 'Change Cipher Spec' is just a single byte, so we know exactly what
         * the record payload has to look like.
         */
        CBS_init(&cbs, rr->data, rr->length);
        if (rr->off != 0 || CBS_len(&cbs) != sizeof(ccs)) {
                SSLerror(s, SSL_R_BAD_CHANGE_CIPHER_SPEC);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                return -1;
        }
        if (!CBS_mem_equal(&cbs, ccs, sizeof(ccs))) {
                SSLerror(s, SSL_R_BAD_CHANGE_CIPHER_SPEC);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
                return -1;
        }

        /* XDTLS: check that epoch is consistent */

        ssl_msg_callback_cbs(s, 0, SSL3_RT_CHANGE_CIPHER_SPEC, &cbs);

        /* Check that we have a cipher to change to. */
        if (s->s3->hs.cipher == NULL) {
                SSLerror(s, SSL_R_CCS_RECEIVED_EARLY);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
                return -1;
        }

        /* Check that we should be receiving a Change Cipher Spec. */
        if (SSL_is_dtls(s)) {
                if (!s->d1->change_cipher_spec_ok) {
                        /*
                         * We can't process a CCS now, because previous
                         * handshake messages are still missing, so just
                         * drop it.
                         */
                        rr->length = 0;
                        return 1;
                }
                s->d1->change_cipher_spec_ok = 0;
        } else {
                if ((s->s3->flags & SSL3_FLAGS_CCS_OK) == 0) {
                        SSLerror(s, SSL_R_CCS_RECEIVED_EARLY);
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_UNEXPECTED_MESSAGE);
                        return -1;
                }
                s->s3->flags &= ~SSL3_FLAGS_CCS_OK;
        }

        rr->length = 0;

        s->s3->change_cipher_spec = 1;
        if (!ssl3_do_change_cipher_spec(s))
                return -1;

        return 1;
}

static int
ssl3_read_handshake_unexpected(SSL *s)
{
        SSL3_RECORD_INTERNAL *rr = &s->s3->rrec;
        uint32_t hs_msg_length;
        uint8_t hs_msg_type;
        CBS cbs;
        int ret;

        /*
         * We need four bytes of handshake data so we have a handshake message
         * header - this may be in the same record or fragmented across multiple
         * records.
         */
        while (rr->length > 0 &&
            s->s3->handshake_fragment_len < sizeof(s->s3->handshake_fragment)) {
                s->s3->handshake_fragment[s->s3->handshake_fragment_len++] =
                    rr->data[rr->off++];
                rr->length--;
        }

        if (s->s3->handshake_fragment_len < sizeof(s->s3->handshake_fragment))
                return 1;

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

        /*
         * This code currently deals with HelloRequest and ClientHello messages -
         * anything else is pushed to the handshake_func. Almost all of this
         * belongs in the client/server handshake code.
         */

        /* Parse handshake message header. */
        CBS_init(&cbs, s->s3->handshake_fragment, s->s3->handshake_fragment_len);
        if (!CBS_get_u8(&cbs, &hs_msg_type))
                return -1;
        if (!CBS_get_u24(&cbs, &hs_msg_length))
                return -1;

        if (hs_msg_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;
                }

                if (hs_msg_length != 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,
                    s->s3->handshake_fragment, s->s3->handshake_fragment_len);

                s->s3->handshake_fragment_len = 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;

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

        } else if (hs_msg_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 {
                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
ssl3_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_read_buffer(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 (type == SSL3_RT_HANDSHAKE && s->s3->handshake_fragment_len > 0) {
                /* Partially satisfy request from fragment storage. */
                unsigned char *src = s->s3->handshake_fragment;
                unsigned char *dst = buf;
                unsigned int k;

                /* peek == 0 */
                n = 0;
                while (len > 0 && s->s3->handshake_fragment_len > 0) {
                        *dst++ = *src++;
                        len--;
                        s->s3->handshake_fragment_len--;
                        n++;
                }
                /* move any remaining fragment bytes: */
                for (k = 0; k < s->s3->handshake_fragment_len; k++)
                        s->s3->handshake_fragment[k] = *src++;
                return n;
        }

        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;

        if (rr->length == 0 || s->internal->rstate == SSL_ST_READ_BODY) {
                if ((ret = ssl3_get_record(s)) <= 0)
                        return ret;
        }

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

        if (s->s3->change_cipher_spec && rr->type != SSL3_RT_HANDSHAKE) {
                SSLerror(s, SSL_R_DATA_BETWEEN_CCS_AND_FINISHED);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
                return -1;
        }

        /*
         * 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;
                                if (s->internal->mode & SSL_MODE_RELEASE_BUFFERS &&
                                    s->s3->rbuf.left == 0)
                                        ssl3_release_read_buffer(s);
                        }
                }

                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 = ssl3_read_handshake_unexpected(s)) <= 0)
                        return ret;
                goto start;
        }

        /*
         * Unknown record type - TLSv1.2 sends an unexpected message alert while
         * earlier versions silently ignore the record.
         */
        if (ssl_effective_tls_version(s) <= TLS1_1_VERSION) {
                rr->length = 0;
                goto start;
        }
        SSLerror(s, SSL_R_UNEXPECTED_RECORD);
        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
        return -1;
}

int
ssl3_do_change_cipher_spec(SSL *s)
{
        if (s->s3->hs.tls12.key_block == NULL) {
                if (s->session == NULL || s->session->master_key_length == 0) {
                        /* might happen if dtls1_read_bytes() calls this */
                        SSLerror(s, SSL_R_CCS_RECEIVED_EARLY);
                        return (0);
                }

                s->session->cipher = s->s3->hs.cipher;
                if (!tls1_setup_key_block(s))
                        return (0);
        }

        if (!tls1_change_read_cipher_state(s))
                return (0);

        /*
         * We have to record the message digest at this point so we can get it
         * before we read the finished message.
         */
        if (!tls12_derive_peer_finished(s))
                return (0);

        return (1);
}

static int
ssl3_write_alert(SSL *s)
{
        if (SSL_is_dtls(s))
                return do_dtls1_write(s, SSL3_RT_ALERT, s->s3->send_alert,
                    sizeof(s->s3->send_alert));

        return do_ssl3_write(s, SSL3_RT_ALERT, s->s3->send_alert,
            sizeof(s->s3->send_alert));
}

int
ssl3_send_alert(SSL *s, int level, int desc)
{
        /* If alert is fatal, remove session from cache. */
        if (level == SSL3_AL_FATAL)
                SSL_CTX_remove_session(s->ctx, s->session);

        s->s3->alert_dispatch = 1;
        s->s3->send_alert[0] = level;
        s->s3->send_alert[1] = desc;

        /*
         * If data is still being written out, the alert will be dispatched at
         * some point in the future.
         */
        if (s->s3->wbuf.left != 0)
                return -1;

        return ssl3_dispatch_alert(s);
}

int
ssl3_dispatch_alert(SSL *s)
{
        int ret;

        s->s3->alert_dispatch = 0;
        if ((ret = ssl3_write_alert(s)) <= 0) {
                s->s3->alert_dispatch = 1;
                return ret;
        }

        /*
         * Alert sent to BIO.  If it is important, flush it now.
         * If the message does not get sent due to non-blocking IO,
         * we will not worry too much.
         */
        if (s->s3->send_alert[0] == SSL3_AL_FATAL)
                (void)BIO_flush(s->wbio);

        ssl_msg_callback(s, 1, SSL3_RT_ALERT, s->s3->send_alert, 2);

        ssl_info_callback(s, SSL_CB_WRITE_ALERT,
            (s->s3->send_alert[0] << 8) | s->s3->send_alert[1]);

        return ret;
}