[thirdparty/openssl.git] / ssl / d1_srvr.c

/* ssl/d1_srvr.c */
/*
 * DTLS implementation written by Nagendra Modadugu
 * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
 */
/* ====================================================================
 * Copyright (c) 1999-2007 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 <stdio.h>
#include "ssl_locl.h"
#include <openssl/buffer.h>
#include <openssl/rand.h>
#include <openssl/objects.h>
#include <openssl/evp.h>
#include <openssl/x509.h>
#include <openssl/md5.h>
#include <openssl/bn.h>
#ifndef OPENSSL_NO_DH
# include <openssl/dh.h>
#endif

static const SSL_METHOD *dtls1_get_server_method(int ver);
static int dtls1_send_hello_verify_request(SSL *s);

static const SSL_METHOD *dtls1_get_server_method(int ver)
{
    if (ver == DTLS1_VERSION)
        return (DTLSv1_server_method());
    else if (ver == DTLS1_2_VERSION)
        return (DTLSv1_2_server_method());
    else
        return (NULL);
}

IMPLEMENT_dtls1_meth_func(DTLS1_VERSION,
                          DTLSv1_server_method,
                          dtls1_accept,
                          ssl_undefined_function,
                          dtls1_get_server_method, DTLSv1_enc_data)

    IMPLEMENT_dtls1_meth_func(DTLS1_2_VERSION,
                          DTLSv1_2_server_method,
                          dtls1_accept,
                          ssl_undefined_function,
                          dtls1_get_server_method, DTLSv1_2_enc_data)

    IMPLEMENT_dtls1_meth_func(DTLS_ANY_VERSION,
                          DTLS_server_method,
                          dtls1_accept,
                          ssl_undefined_function,
                          dtls1_get_server_method, DTLSv1_2_enc_data)

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

    RAND_add(&Time, sizeof(Time), 0);
    ERR_clear_error();
    clear_sys_error();

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

    listen = s->d1->listen;

    /* init things to blank */
    s->in_handshake++;
    if (!SSL_in_init(s) || SSL_in_before(s)) {
        if(!SSL_clear(s))
            return -1;
    }

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

#ifndef OPENSSL_NO_HEARTBEATS
    /*
     * If we're awaiting a HeartbeatResponse, pretend we already got and
     * don't await it anymore, because Heartbeats don't make sense during
     * handshakes anyway.
     */
    if (s->tlsext_hb_pending) {
        dtls1_stop_timer(s);
        s->tlsext_hb_pending = 0;
        s->tlsext_hb_seq++;
    }
#endif

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

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

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

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

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

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

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

            s->init_num = 0;
            s->d1->change_cipher_spec_ok = 0;
            /*
             * Should have been reset by ssl3_get_finished, too.
             */
            s->s3->change_cipher_spec = 0;

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

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

            break;

        case SSL3_ST_SW_HELLO_REQ_A:
        case SSL3_ST_SW_HELLO_REQ_B:

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

            ssl3_init_finished_mac(s);
            break;

        case SSL3_ST_SW_HELLO_REQ_C:
            s->state = SSL_ST_OK;
            break;

        case SSL3_ST_SR_CLNT_HELLO_A:
        case SSL3_ST_SR_CLNT_HELLO_B:
        case SSL3_ST_SR_CLNT_HELLO_C:

            s->shutdown = 0;
            ret = ssl3_get_client_hello(s);
            if (ret <= 0)
                goto end;
            dtls1_stop_timer(s);

            if (ret == 1 && (SSL_get_options(s) & SSL_OP_COOKIE_EXCHANGE))
                s->state = DTLS1_ST_SW_HELLO_VERIFY_REQUEST_A;
            else
                s->state = SSL3_ST_SW_SRVR_HELLO_A;

            s->init_num = 0;

            /*
             * Reflect ClientHello sequence to remain stateless while
             * listening
             */
            if (listen) {
                memcpy(s->s3->write_sequence, s->s3->read_sequence,
                       sizeof(s->s3->write_sequence));
            }

            /* If we're just listening, stop here */
            if (listen && s->state == SSL3_ST_SW_SRVR_HELLO_A) {
                ret = 2;
                s->d1->listen = 0;
                /*
                 * Set expected sequence numbers to continue the handshake.
                 */
                s->d1->handshake_read_seq = 2;
                s->d1->handshake_write_seq = 1;
                s->d1->next_handshake_write_seq = 1;
                goto end;
            }

            break;

        case DTLS1_ST_SW_HELLO_VERIFY_REQUEST_A:
        case DTLS1_ST_SW_HELLO_VERIFY_REQUEST_B:

            ret = dtls1_send_hello_verify_request(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_SW_FLUSH;
            s->s3->tmp.next_state = SSL3_ST_SR_CLNT_HELLO_A;

            /* HelloVerifyRequest resets Finished MAC */
            if (s->version != DTLS1_BAD_VER)
                ssl3_init_finished_mac(s);
            break;

#ifndef OPENSSL_NO_SCTP
        case DTLS1_SCTP_ST_SR_READ_SOCK:

            if (BIO_dgram_sctp_msg_waiting(SSL_get_rbio(s))) {
                s->s3->in_read_app_data = 2;
                s->rwstate = SSL_READING;
                BIO_clear_retry_flags(SSL_get_rbio(s));
                BIO_set_retry_read(SSL_get_rbio(s));
                ret = -1;
                goto end;
            }

            s->state = SSL3_ST_SR_FINISHED_A;
            break;

        case DTLS1_SCTP_ST_SW_WRITE_SOCK:
            ret = BIO_dgram_sctp_wait_for_dry(SSL_get_wbio(s));
            if (ret < 0)
                goto end;

            if (ret == 0) {
                if (s->d1->next_state != SSL_ST_OK) {
                    s->s3->in_read_app_data = 2;
                    s->rwstate = SSL_READING;
                    BIO_clear_retry_flags(SSL_get_rbio(s));
                    BIO_set_retry_read(SSL_get_rbio(s));
                    ret = -1;
                    goto end;
                }
            }

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

        case SSL3_ST_SW_SRVR_HELLO_A:
        case SSL3_ST_SW_SRVR_HELLO_B:
            s->renegotiate = 2;
            dtls1_start_timer(s);
            ret = ssl3_send_server_hello(s);
            if (ret <= 0)
                goto end;

            if (s->hit) {
#ifndef OPENSSL_NO_SCTP
                /*
                 * Add new shared key for SCTP-Auth, will be ignored if no
                 * SCTP used.
                 */
                snprintf((char *)labelbuffer, sizeof(DTLS1_SCTP_AUTH_LABEL),
                         DTLS1_SCTP_AUTH_LABEL);

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

                BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_ADD_AUTH_KEY,
                         sizeof(sctpauthkey), sctpauthkey);
#endif
#ifndef OPENSSL_NO_TLSEXT
                if (s->tlsext_ticket_expected)
                    s->state = SSL3_ST_SW_SESSION_TICKET_A;
                else
                    s->state = SSL3_ST_SW_CHANGE_A;
#else
                s->state = SSL3_ST_SW_CHANGE_A;
#endif
            } else
                s->state = SSL3_ST_SW_CERT_A;
            s->init_num = 0;
            break;

        case SSL3_ST_SW_CERT_A:
        case SSL3_ST_SW_CERT_B:
            /* Check if it is anon DH or normal PSK */
            if (!(s->s3->tmp.new_cipher->algorithm_auth & SSL_aNULL)
                && !(s->s3->tmp.new_cipher->algorithm_mkey & SSL_kPSK)) {
                dtls1_start_timer(s);
                ret = ssl3_send_server_certificate(s);
                if (ret <= 0)
                    goto end;
#ifndef OPENSSL_NO_TLSEXT
                if (s->tlsext_status_expected)
                    s->state = SSL3_ST_SW_CERT_STATUS_A;
                else
                    s->state = SSL3_ST_SW_KEY_EXCH_A;
            } else {
                skip = 1;
                s->state = SSL3_ST_SW_KEY_EXCH_A;
            }
#else
            } else
                skip = 1;

            s->state = SSL3_ST_SW_KEY_EXCH_A;
#endif
            s->init_num = 0;
            break;

        case SSL3_ST_SW_KEY_EXCH_A:
        case SSL3_ST_SW_KEY_EXCH_B:
            alg_k = s->s3->tmp.new_cipher->algorithm_mkey;

            /*
             * clear this, it may get reset by
             * send_server_key_exchange
             */
            s->s3->tmp.use_rsa_tmp = 0;

            /*
             * only send if a DH key exchange or RSA but we have a sign only
             * certificate
             */
            if (0
                /*
                 * PSK: send ServerKeyExchange if PSK identity hint if
                 * provided
                 */
#ifndef OPENSSL_NO_PSK
                || ((alg_k & SSL_kPSK) && s->ctx->psk_identity_hint)
#endif
                || (alg_k & (SSL_kDHE | SSL_kDHr | SSL_kDHd))
                || (alg_k & SSL_kECDHE)
                || ((alg_k & SSL_kRSA)
                    && (s->cert->pkeys[SSL_PKEY_RSA_ENC].privatekey == NULL
                        || (SSL_C_IS_EXPORT(s->s3->tmp.new_cipher)
                            && EVP_PKEY_size(s->cert->pkeys
                                             [SSL_PKEY_RSA_ENC].privatekey) *
                            8 > SSL_C_EXPORT_PKEYLENGTH(s->s3->tmp.new_cipher)
                        )
                    )
                )
                ) {
                dtls1_start_timer(s);
                ret = ssl3_send_server_key_exchange(s);
                if (ret <= 0)
                    goto end;
            } else
                skip = 1;

            s->state = SSL3_ST_SW_CERT_REQ_A;
            s->init_num = 0;
            break;

        case SSL3_ST_SW_CERT_REQ_A:
        case SSL3_ST_SW_CERT_REQ_B:
            if (                /* don't request cert unless asked for it: */
                   !(s->verify_mode & SSL_VERIFY_PEER) ||
                   /*
                    * if SSL_VERIFY_CLIENT_ONCE is set, don't request cert
                    * during re-negotiation:
                    */
                   ((s->session->peer != NULL) &&
                    (s->verify_mode & SSL_VERIFY_CLIENT_ONCE)) ||
                   /*
                    * never request cert in anonymous ciphersuites (see
                    * section "Certificate request" in SSL 3 drafts and in
                    * RFC 2246):
                    */
                   ((s->s3->tmp.new_cipher->algorithm_auth & SSL_aNULL) &&
                    /*
                     * ... except when the application insists on
                     * verification (against the specs, but s3_clnt.c accepts
                     * this for SSL 3)
                     */
                    !(s->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT)) ||
                   /*
                    * never request cert in Kerberos ciphersuites
                    */
                   (s->s3->tmp.new_cipher->algorithm_auth & SSL_aKRB5)
                   /*
                    * With normal PSK Certificates and Certificate Requests
                    * are omitted
                    */
                   || (s->s3->tmp.new_cipher->algorithm_mkey & SSL_kPSK)) {
                /* no cert request */
                skip = 1;
                s->s3->tmp.cert_request = 0;
                s->state = SSL3_ST_SW_SRVR_DONE_A;
#ifndef OPENSSL_NO_SCTP
                if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
                    s->d1->next_state = SSL3_ST_SW_SRVR_DONE_A;
                    s->state = DTLS1_SCTP_ST_SW_WRITE_SOCK;
                }
#endif
            } else {
                s->s3->tmp.cert_request = 1;
                dtls1_start_timer(s);
                ret = ssl3_send_certificate_request(s);
                if (ret <= 0)
                    goto end;
                s->state = SSL3_ST_SW_SRVR_DONE_A;
# ifndef OPENSSL_NO_SCTP
                if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
                    s->d1->next_state = SSL3_ST_SW_SRVR_DONE_A;
                    s->state = DTLS1_SCTP_ST_SW_WRITE_SOCK;
                }
# endif
                s->init_num = 0;
            }
            break;

        case SSL3_ST_SW_SRVR_DONE_A:
        case SSL3_ST_SW_SRVR_DONE_B:
            dtls1_start_timer(s);
            ret = ssl3_send_server_done(s);
            if (ret <= 0)
                goto end;
            s->s3->tmp.next_state = SSL3_ST_SR_CERT_A;
            s->state = SSL3_ST_SW_FLUSH;
            s->init_num = 0;
            break;

        case SSL3_ST_SW_FLUSH:
            s->rwstate = SSL_WRITING;
            if (BIO_flush(s->wbio) <= 0) {
                /*
                 * If the write error was fatal, stop trying
                 */
                if (!BIO_should_retry(s->wbio)) {
                    s->rwstate = SSL_NOTHING;
                    s->state = s->s3->tmp.next_state;
                }

                ret = -1;
                goto end;
            }
            s->rwstate = SSL_NOTHING;
            s->state = s->s3->tmp.next_state;
            break;

        case SSL3_ST_SR_CERT_A:
        case SSL3_ST_SR_CERT_B:
            if (s->s3->tmp.cert_request) {
                ret = ssl3_get_client_certificate(s);
                if (ret <= 0)
                    goto end;
            }
            s->init_num = 0;
            s->state = SSL3_ST_SR_KEY_EXCH_A;
            break;

        case SSL3_ST_SR_KEY_EXCH_A:
        case SSL3_ST_SR_KEY_EXCH_B:
            ret = ssl3_get_client_key_exchange(s);
            if (ret <= 0)
                goto end;
#ifndef OPENSSL_NO_SCTP
            /*
             * Add new shared key for SCTP-Auth, will be ignored if no SCTP
             * used.
             */
            snprintf((char *)labelbuffer, sizeof(DTLS1_SCTP_AUTH_LABEL),
                     DTLS1_SCTP_AUTH_LABEL);

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

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

            s->state = SSL3_ST_SR_CERT_VRFY_A;
            s->init_num = 0;

            if (ret == 2) {
                /*
                 * For the ECDH ciphersuites when the client sends its ECDH
                 * pub key in a certificate, the CertificateVerify message is
                 * not sent.
                 */
                s->state = SSL3_ST_SR_FINISHED_A;
                s->init_num = 0;
            } else if (SSL_USE_SIGALGS(s)) {
                s->state = SSL3_ST_SR_CERT_VRFY_A;
                s->init_num = 0;
                if (!s->session->peer)
                    break;
                if (!s->s3->handshake_buffer) {
                    SSLerr(SSL_F_DTLS1_ACCEPT, ERR_R_INTERNAL_ERROR);
                    return -1;
                }
                /*
                 * For sigalgs freeze the handshake buffer. If we support
                 * extms we've done this already.
                 */
                if (!(s->s3->flags & SSL_SESS_FLAG_EXTMS)) {
                    s->s3->flags |= TLS1_FLAGS_KEEP_HANDSHAKE;
                    if (!ssl3_digest_cached_records(s))
                        return -1;
                }
            } else {
                s->state = SSL3_ST_SR_CERT_VRFY_A;
                s->init_num = 0;

                /*
                 * We need to get hashes here so if there is a client cert,
                 * it can be verified
                 */
                s->method->ssl3_enc->cert_verify_mac(s,
                                                     NID_md5,
                                                     &(s->s3->
                                                       tmp.cert_verify_md
                                                       [0]));
                s->method->ssl3_enc->cert_verify_mac(s, NID_sha1,
                                                     &(s->s3->
                                                       tmp.cert_verify_md
                                                       [MD5_DIGEST_LENGTH]));
            }
            break;

        case SSL3_ST_SR_CERT_VRFY_A:
        case SSL3_ST_SR_CERT_VRFY_B:
            /*
             * This *should* be the first time we enable CCS, but be
             * extra careful about surrounding code changes. We need
             * to set this here because we don't know if we're
             * expecting a CertificateVerify or not.
             */
            if (!s->s3->change_cipher_spec)
                s->d1->change_cipher_spec_ok = 1;
            /* we should decide if we expected this one */
            ret = ssl3_get_cert_verify(s);
            if (ret <= 0)
                goto end;
#ifndef OPENSSL_NO_SCTP
            if (BIO_dgram_is_sctp(SSL_get_wbio(s)) &&
                state == SSL_ST_RENEGOTIATE)
                s->state = DTLS1_SCTP_ST_SR_READ_SOCK;
            else
#endif
                s->state = SSL3_ST_SR_FINISHED_A;
            s->init_num = 0;
            break;

        case SSL3_ST_SR_FINISHED_A:
        case SSL3_ST_SR_FINISHED_B:
            /*
             * Enable CCS for resumed handshakes.
             * In a full handshake, we end up here through
             * SSL3_ST_SR_CERT_VRFY_B, so change_cipher_spec_ok was
             * already set. Receiving a CCS clears the flag, so make
             * sure not to re-enable it to ban duplicates.
             * s->s3->change_cipher_spec is set when a CCS is
             * processed in d1_pkt.c, and remains set until
             * the client's Finished message is read.
             */
            if (!s->s3->change_cipher_spec)
                s->d1->change_cipher_spec_ok = 1;
            ret = ssl3_get_finished(s, SSL3_ST_SR_FINISHED_A,
                                    SSL3_ST_SR_FINISHED_B);
            if (ret <= 0)
                goto end;
            dtls1_stop_timer(s);
            if (s->hit)
                s->state = SSL_ST_OK;
#ifndef OPENSSL_NO_TLSEXT
            else if (s->tlsext_ticket_expected)
                s->state = SSL3_ST_SW_SESSION_TICKET_A;
#endif
            else
                s->state = SSL3_ST_SW_CHANGE_A;
            s->init_num = 0;
            break;

#ifndef OPENSSL_NO_TLSEXT
        case SSL3_ST_SW_SESSION_TICKET_A:
        case SSL3_ST_SW_SESSION_TICKET_B:
            ret = ssl3_send_newsession_ticket(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_SW_CHANGE_A;
            s->init_num = 0;
            break;

        case SSL3_ST_SW_CERT_STATUS_A:
        case SSL3_ST_SW_CERT_STATUS_B:
            ret = ssl3_send_cert_status(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_SW_KEY_EXCH_A;
            s->init_num = 0;
            break;

#endif

        case SSL3_ST_SW_CHANGE_A:
        case SSL3_ST_SW_CHANGE_B:

            s->session->cipher = s->s3->tmp.new_cipher;
            if (!s->method->ssl3_enc->setup_key_block(s)) {
                ret = -1;
                goto end;
            }

            ret = dtls1_send_change_cipher_spec(s,
                                                SSL3_ST_SW_CHANGE_A,
                                                SSL3_ST_SW_CHANGE_B);

            if (ret <= 0)
                goto end;

#ifndef OPENSSL_NO_SCTP
            if (!s->hit) {
                /*
                 * Change to new shared key of SCTP-Auth, will be ignored if
                 * no SCTP used.
                 */
                BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_NEXT_AUTH_KEY,
                         0, NULL);
            }
#endif

            s->state = SSL3_ST_SW_FINISHED_A;
            s->init_num = 0;

            if (!s->method->ssl3_enc->change_cipher_state(s,
                                                          SSL3_CHANGE_CIPHER_SERVER_WRITE))
            {
                ret = -1;
                goto end;
            }

            dtls1_reset_seq_numbers(s, SSL3_CC_WRITE);
            break;

        case SSL3_ST_SW_FINISHED_A:
        case SSL3_ST_SW_FINISHED_B:
            ret = ssl3_send_finished(s,
                                     SSL3_ST_SW_FINISHED_A,
                                     SSL3_ST_SW_FINISHED_B,
                                     s->method->
                                     ssl3_enc->server_finished_label,
                                     s->method->
                                     ssl3_enc->server_finished_label_len);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_SW_FLUSH;
            if (s->hit) {
                s->s3->tmp.next_state = SSL3_ST_SR_FINISHED_A;

#ifndef OPENSSL_NO_SCTP
                /*
                 * Change to new shared key of SCTP-Auth, will be ignored if
                 * no SCTP used.
                 */
                BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_NEXT_AUTH_KEY,
                         0, NULL);
#endif
            } else {
                s->s3->tmp.next_state = SSL_ST_OK;
#ifndef OPENSSL_NO_SCTP
                if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
                    s->d1->next_state = s->s3->tmp.next_state;
                    s->s3->tmp.next_state = DTLS1_SCTP_ST_SW_WRITE_SOCK;
                }
#endif
            }
            s->init_num = 0;
            break;

        case SSL_ST_OK:
            /* clean a few things up */
            ssl3_cleanup_key_block(s);

            /* remove buffering on output */
            ssl_free_wbio_buffer(s);

            s->init_num = 0;

            if (s->renegotiate == 2) { /* skipped if we just sent a
                                        * HelloRequest */
                s->renegotiate = 0;
                s->new_session = 0;

                ssl_update_cache(s, SSL_SESS_CACHE_SERVER);

                s->ctx->stats.sess_accept_good++;
                /* s->server=1; */
                s->handshake_func = dtls1_accept;

                if (cb != NULL)
                    cb(s, SSL_CB_HANDSHAKE_DONE, 1);
            }

            ret = 1;

            /* done handshaking, next message is client hello */
            s->d1->handshake_read_seq = 0;
            /* next message is server hello */
            s->d1->handshake_write_seq = 0;
            s->d1->next_handshake_write_seq = 0;
            goto end;
            /* break; */

        default:
            SSLerr(SSL_F_DTLS1_ACCEPT, SSL_R_UNKNOWN_STATE);
            ret = -1;
            goto end;
            /* break; */
        }

        if (!s->s3->tmp.reuse_message && !skip) {
            if (s->debug) {
                if ((ret = BIO_flush(s->wbio)) <= 0)
                    goto end;
            }

            if ((cb != NULL) && (s->state != state)) {
                new_state = s->state;
                s->state = state;
                cb(s, SSL_CB_ACCEPT_LOOP, 1);
                s->state = new_state;
            }
        }
        skip = 0;
    }
 end:
    /* BIO_flush(s->wbio); */

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

    if (cb != NULL)
        cb(s, SSL_CB_ACCEPT_EXIT, ret);
    return (ret);
}

int dtls1_send_hello_verify_request(SSL *s)
{
    unsigned int msg_len;
    unsigned char *msg, *buf, *p;

    if (s->state == DTLS1_ST_SW_HELLO_VERIFY_REQUEST_A) {
        buf = (unsigned char *)s->init_buf->data;

        msg = p = &(buf[DTLS1_HM_HEADER_LENGTH]);
        /* Always use DTLS 1.0 version: see RFC 6347 */
        *(p++) = DTLS1_VERSION >> 8;
        *(p++) = DTLS1_VERSION & 0xFF;

        if (s->ctx->app_gen_cookie_cb == NULL ||
            s->ctx->app_gen_cookie_cb(s, s->d1->cookie,
                                      &(s->d1->cookie_len)) == 0) {
            SSLerr(SSL_F_DTLS1_SEND_HELLO_VERIFY_REQUEST,
                   ERR_R_INTERNAL_ERROR);
            return 0;
        }

        *(p++) = (unsigned char)s->d1->cookie_len;
        memcpy(p, s->d1->cookie, s->d1->cookie_len);
        p += s->d1->cookie_len;
        msg_len = p - msg;

        dtls1_set_message_header(s, buf,
                                 DTLS1_MT_HELLO_VERIFY_REQUEST, msg_len, 0,
                                 msg_len);

        s->state = DTLS1_ST_SW_HELLO_VERIFY_REQUEST_B;
        /* number of bytes to write */
        s->init_num = p - buf;
        s->init_off = 0;
    }

    /* s->state = DTLS1_ST_SW_HELLO_VERIFY_REQUEST_B */
    return (dtls1_do_write(s, SSL3_RT_HANDSHAKE));
}