openssl/ssl/s23_clnt.c

/* ssl/s23_clnt.c */
/* 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) 1998-2006 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 <stdio.h>
#include "ssl_locl.h"
#include <openssl/buffer.h>
#include <openssl/rand.h>
#include <openssl/objects.h>
#include <openssl/evp.h>

static const SSL_METHOD *ssl23_get_client_method(int ver);
static int ssl23_client_hello(SSL *s);
static int ssl23_get_server_hello(SSL *s);
static const SSL_METHOD *ssl23_get_client_method(int ver)
{
#ifndef OPENSSL_NO_SSL2
    if (ver == SSL2_VERSION)
        return (SSLv2_client_method());
#endif
#ifndef OPENSSL_NO_SSL3
    if (ver == SSL3_VERSION)
        return (SSLv3_client_method());
#endif
    if (ver == TLS1_VERSION)
        return (TLSv1_client_method());
    else if (ver == TLS1_1_VERSION)
        return (TLSv1_1_client_method());
    else if (ver == TLS1_2_VERSION)
        return (TLSv1_2_client_method());
    else
        return (NULL);
}

IMPLEMENT_ssl23_meth_func(SSLv23_client_method,
                          ssl_undefined_function,
                          ssl23_connect, ssl23_get_client_method)

int ssl23_connect(SSL *s)
{
    BUF_MEM *buf = NULL;
    unsigned long Time = (unsigned long)time(NULL);
    void (*cb) (const SSL *ssl, int type, int val) = NULL;
    int ret = -1;
    int new_state, state;

    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;

    s->in_handshake++;
    if (!SSL_in_init(s) || SSL_in_before(s))
        SSL_clear(s);

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

        switch (s->state) {
        case SSL_ST_BEFORE:
        case SSL_ST_CONNECT:
        case SSL_ST_BEFORE | SSL_ST_CONNECT:
        case SSL_ST_OK | SSL_ST_CONNECT:

            if (s->session != NULL) {
                SSLerr(SSL_F_SSL23_CONNECT,
                       SSL_R_SSL23_DOING_SESSION_ID_REUSE);
                ret = -1;
                goto end;
            }
            s->server = 0;
            if (cb != NULL)
                cb(s, SSL_CB_HANDSHAKE_START, 1);

            /* s->version=TLS1_VERSION; */
            s->type = SSL_ST_CONNECT;

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

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

            ssl3_init_finished_mac(s);

            s->state = SSL23_ST_CW_CLNT_HELLO_A;
            s->ctx->stats.sess_connect++;
            s->init_num = 0;
            break;

        case SSL23_ST_CW_CLNT_HELLO_A:
        case SSL23_ST_CW_CLNT_HELLO_B:

            s->shutdown = 0;
            ret = ssl23_client_hello(s);
            if (ret <= 0)
                goto end;
            s->state = SSL23_ST_CR_SRVR_HELLO_A;
            s->init_num = 0;

            break;

        case SSL23_ST_CR_SRVR_HELLO_A:
        case SSL23_ST_CR_SRVR_HELLO_B:
            ret = ssl23_get_server_hello(s);
            if (ret >= 0)
                cb = NULL;
            goto end;
            /* break; */

        default:
            SSLerr(SSL_F_SSL23_CONNECT, SSL_R_UNKNOWN_STATE);
            ret = -1;
            goto end;
            /* break; */
        }

        if (s->debug) {
            (void)BIO_flush(s->wbio);
        }

        if ((cb != NULL) && (s->state != state)) {
            new_state = s->state;
            s->state = state;
            cb(s, SSL_CB_CONNECT_LOOP, 1);
            s->state = new_state;
        }
    }
 end:
    s->in_handshake--;
    if (buf != NULL)
        BUF_MEM_free(buf);
    if (cb != NULL)
        cb(s, SSL_CB_CONNECT_EXIT, ret);
    return (ret);
}

static int ssl23_no_ssl2_ciphers(SSL *s)
{
    SSL_CIPHER *cipher;
    STACK_OF(SSL_CIPHER) *ciphers;
    int i;
    ciphers = SSL_get_ciphers(s);
    for (i = 0; i < sk_SSL_CIPHER_num(ciphers); i++) {
        cipher = sk_SSL_CIPHER_value(ciphers, i);
        if (cipher->algorithm_ssl == SSL_SSLV2)
            return 0;
    }
    return 1;
}

/*
 * Fill a ClientRandom or ServerRandom field of length len. Returns <= 0 on
 * failure, 1 on success.
 */
int ssl_fill_hello_random(SSL *s, int server, unsigned char *result, int len)
{
    int send_time = 0;
    if (len < 4)
        return 0;
    if (server)
        send_time = (s->mode & SSL_MODE_SEND_SERVERHELLO_TIME) != 0;
    else
        send_time = (s->mode & SSL_MODE_SEND_CLIENTHELLO_TIME) != 0;
    if (send_time) {
        unsigned long Time = (unsigned long)time(NULL);
        unsigned char *p = result;
        l2n(Time, p);
        return RAND_pseudo_bytes(p, len - 4);
    } else
        return RAND_pseudo_bytes(result, len);
}

static int ssl23_client_hello(SSL *s)
{
    unsigned char *buf;
    unsigned char *p, *d;
    int i, ch_len;
    unsigned long l;
    int ssl2_compat;
    int version = 0, version_major, version_minor;
    int al = 0;
#ifndef OPENSSL_NO_COMP
    int j;
    SSL_COMP *comp;
#endif
    int ret;
    unsigned long mask, options = s->options;

    ssl2_compat = (options & SSL_OP_NO_SSLv2) ? 0 : 1;

    if (ssl2_compat && ssl23_no_ssl2_ciphers(s))
        ssl2_compat = 0;

    /*
     * SSL_OP_NO_X disables all protocols above X *if* there are
     * some protocols below X enabled. This is required in order
     * to maintain "version capability" vector contiguous. So
     * that if application wants to disable TLS1.0 in favour of
     * TLS1>=1, it would be insufficient to pass SSL_NO_TLSv1, the
     * answer is SSL_OP_NO_TLSv1|SSL_OP_NO_SSLv3|SSL_OP_NO_SSLv2.
     */
    mask = SSL_OP_NO_TLSv1_1 | SSL_OP_NO_TLSv1
#if !defined(OPENSSL_NO_SSL3)
        | SSL_OP_NO_SSLv3
#endif
#if !defined(OPENSSL_NO_SSL2)
        | (ssl2_compat ? SSL_OP_NO_SSLv2 : 0)
#endif
        ;
#if !defined(OPENSSL_NO_TLS1_2_CLIENT)
    version = TLS1_2_VERSION;

    if ((options & SSL_OP_NO_TLSv1_2) && (options & mask) != mask)
        version = TLS1_1_VERSION;
#else
    version = TLS1_1_VERSION;
#endif
    mask &= ~SSL_OP_NO_TLSv1_1;
    if ((options & SSL_OP_NO_TLSv1_1) && (options & mask) != mask)
        version = TLS1_VERSION;
    mask &= ~SSL_OP_NO_TLSv1;
#if !defined(OPENSSL_NO_SSL3)
    if ((options & SSL_OP_NO_TLSv1) && (options & mask) != mask)
        version = SSL3_VERSION;
    mask &= ~SSL_OP_NO_SSLv3;
#endif
#if !defined(OPENSSL_NO_SSL2)
    if ((options & SSL_OP_NO_SSLv3) && (options & mask) != mask)
        version = SSL2_VERSION;
#endif

#ifndef OPENSSL_NO_TLSEXT
    if (version != SSL2_VERSION) {
        /*
         * have to disable SSL 2.0 compatibility if we need TLS extensions
         */

        if (s->tlsext_hostname != NULL)
            ssl2_compat = 0;
        if (s->tlsext_status_type != -1)
            ssl2_compat = 0;
# ifdef TLSEXT_TYPE_opaque_prf_input
        if (s->ctx->tlsext_opaque_prf_input_callback != 0
            || s->tlsext_opaque_prf_input != NULL)
            ssl2_compat = 0;
# endif
        if (s->cert->cli_ext.meths_count != 0)
            ssl2_compat = 0;
    }
#endif

    buf = (unsigned char *)s->init_buf->data;
    if (s->state == SSL23_ST_CW_CLNT_HELLO_A) {
        /*
         * Since we're sending s23 client hello, we're not reusing a session, as
         * we'd be using the method from the saved session instead
         */
        if (!ssl_get_new_session(s, 0)) {
            return -1;
        }

        p = s->s3->client_random;
        if (ssl_fill_hello_random(s, 0, p, SSL3_RANDOM_SIZE) <= 0)
            return -1;

        if (version == TLS1_2_VERSION) {
            version_major = TLS1_2_VERSION_MAJOR;
            version_minor = TLS1_2_VERSION_MINOR;
        } else if (tls1_suiteb(s)) {
            SSLerr(SSL_F_SSL23_CLIENT_HELLO,
                   SSL_R_ONLY_TLS_1_2_ALLOWED_IN_SUITEB_MODE);
            return -1;
        } else if (version == TLS1_1_VERSION) {
            version_major = TLS1_1_VERSION_MAJOR;
            version_minor = TLS1_1_VERSION_MINOR;
        } else if (version == TLS1_VERSION) {
            version_major = TLS1_VERSION_MAJOR;
            version_minor = TLS1_VERSION_MINOR;
        }
#ifdef OPENSSL_FIPS
        else if (FIPS_mode()) {
            SSLerr(SSL_F_SSL23_CLIENT_HELLO,
                   SSL_R_ONLY_TLS_ALLOWED_IN_FIPS_MODE);
            return -1;
        }
#endif
        else if (version == SSL3_VERSION) {
            version_major = SSL3_VERSION_MAJOR;
            version_minor = SSL3_VERSION_MINOR;
        } else if (version == SSL2_VERSION) {
            version_major = SSL2_VERSION_MAJOR;
            version_minor = SSL2_VERSION_MINOR;
        } else {
            SSLerr(SSL_F_SSL23_CLIENT_HELLO, SSL_R_NO_PROTOCOLS_AVAILABLE);
            return (-1);
        }

        s->client_version = version;

        if (ssl2_compat) {
            /* create SSL 2.0 compatible Client Hello */

            /* two byte record header will be written last */
            d = &(buf[2]);
            p = d + 9;          /* leave space for message type, version,
                                 * individual length fields */

            *(d++) = SSL2_MT_CLIENT_HELLO;
            *(d++) = version_major;
            *(d++) = version_minor;

            /* Ciphers supported */
            i = ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s), p, 0);
            if (i == 0) {
                /* no ciphers */
                SSLerr(SSL_F_SSL23_CLIENT_HELLO, SSL_R_NO_CIPHERS_AVAILABLE);
                return -1;
            }
            s2n(i, d);
            p += i;

            /*
             * put in the session-id length (zero since there is no reuse)
             */
            s2n(0, d);

            if (s->options & SSL_OP_NETSCAPE_CHALLENGE_BUG)
                ch_len = SSL2_CHALLENGE_LENGTH;
            else
                ch_len = SSL2_MAX_CHALLENGE_LENGTH;

            /* write out sslv2 challenge */
            /*
             * Note that ch_len must be <= SSL3_RANDOM_SIZE (32), because it
             * is one of SSL2_MAX_CHALLENGE_LENGTH (32) or
             * SSL2_MAX_CHALLENGE_LENGTH (16), but leave the check in for
             * futurproofing
             */
            if (SSL3_RANDOM_SIZE < ch_len)
                i = SSL3_RANDOM_SIZE;
            else
                i = ch_len;
            s2n(i, d);
            memset(&(s->s3->client_random[0]), 0, SSL3_RANDOM_SIZE);
            if (RAND_pseudo_bytes
                (&(s->s3->client_random[SSL3_RANDOM_SIZE - i]), i) <= 0)
                return -1;

            memcpy(p, &(s->s3->client_random[SSL3_RANDOM_SIZE - i]), i);
            p += i;

            i = p - &(buf[2]);
            buf[0] = ((i >> 8) & 0xff) | 0x80;
            buf[1] = (i & 0xff);

            /* number of bytes to write */
            s->init_num = i + 2;
            s->init_off = 0;

            ssl3_finish_mac(s, &(buf[2]), i);
        } else {
            /* create Client Hello in SSL 3.0/TLS 1.0 format */

            /*
             * do the record header (5 bytes) and handshake message header (4
             * bytes) last
             */
            d = p = &(buf[9]);

            *(p++) = version_major;
            *(p++) = version_minor;

            /* Random stuff */
            memcpy(p, s->s3->client_random, SSL3_RANDOM_SIZE);
            p += SSL3_RANDOM_SIZE;

            /* Session ID (zero since there is no reuse) */
            *(p++) = 0;

            /* Ciphers supported (using SSL 3.0/TLS 1.0 format) */
            i = ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s), &(p[2]),
                                         ssl3_put_cipher_by_char);
            if (i == 0) {
                SSLerr(SSL_F_SSL23_CLIENT_HELLO, SSL_R_NO_CIPHERS_AVAILABLE);
                return -1;
            }
#ifdef OPENSSL_MAX_TLS1_2_CIPHER_LENGTH
            /*
             * Some servers hang if client hello > 256 bytes as hack
             * workaround chop number of supported ciphers to keep it well
             * below this if we use TLS v1.2
             */
            if (TLS1_get_version(s) >= TLS1_2_VERSION
                && i > OPENSSL_MAX_TLS1_2_CIPHER_LENGTH)
                i = OPENSSL_MAX_TLS1_2_CIPHER_LENGTH & ~1;
#endif
            s2n(i, p);
            p += i;

            /* COMPRESSION */
#ifdef OPENSSL_NO_COMP
            *(p++) = 1;
#else
            if ((s->options & SSL_OP_NO_COMPRESSION)
                || !s->ctx->comp_methods)
                j = 0;
            else
                j = sk_SSL_COMP_num(s->ctx->comp_methods);
            *(p++) = 1 + j;
            for (i = 0; i < j; i++) {
                comp = sk_SSL_COMP_value(s->ctx->comp_methods, i);
                *(p++) = comp->id;
            }
#endif
            *(p++) = 0;         /* Add the NULL method */

#ifndef OPENSSL_NO_TLSEXT
            /* TLS extensions */
            if (ssl_prepare_clienthello_tlsext(s) <= 0) {
                SSLerr(SSL_F_SSL23_CLIENT_HELLO, SSL_R_CLIENTHELLO_TLSEXT);
                return -1;
            }
            if ((p =
                 ssl_add_clienthello_tlsext(s, p,
                                            buf + SSL3_RT_MAX_PLAIN_LENGTH,
                                            &al)) == NULL) {
                ssl3_send_alert(s, SSL3_AL_FATAL, al);
                SSLerr(SSL_F_SSL23_CLIENT_HELLO, ERR_R_INTERNAL_ERROR);
                return -1;
            }
#endif

            l = p - d;

            /* fill in 4-byte handshake header */
            d = &(buf[5]);
            *(d++) = SSL3_MT_CLIENT_HELLO;
            l2n3(l, d);

            l += 4;

            if (l > SSL3_RT_MAX_PLAIN_LENGTH) {
                SSLerr(SSL_F_SSL23_CLIENT_HELLO, ERR_R_INTERNAL_ERROR);
                return -1;
            }

            /* fill in 5-byte record header */
            d = buf;
            *(d++) = SSL3_RT_HANDSHAKE;
            *(d++) = version_major;
            /*
             * Some servers hang if we use long client hellos and a record
             * number > TLS 1.0.
             */
            if (TLS1_get_client_version(s) > TLS1_VERSION)
                *(d++) = 1;
            else
                *(d++) = version_minor;
            s2n((int)l, d);

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

            ssl3_finish_mac(s, &(buf[5]), s->init_num - 5);
        }

        s->state = SSL23_ST_CW_CLNT_HELLO_B;
        s->init_off = 0;
    }

    /* SSL3_ST_CW_CLNT_HELLO_B */
    ret = ssl23_write_bytes(s);

    if ((ret >= 2) && s->msg_callback) {
        /* Client Hello has been sent; tell msg_callback */

        if (ssl2_compat)
            s->msg_callback(1, SSL2_VERSION, 0, s->init_buf->data + 2,
                            ret - 2, s, s->msg_callback_arg);
        else {
            s->msg_callback(1, version, SSL3_RT_HEADER, s->init_buf->data, 5,
                            s, s->msg_callback_arg);
            s->msg_callback(1, version, SSL3_RT_HANDSHAKE,
                            s->init_buf->data + 5, ret - 5, s,
                            s->msg_callback_arg);
        }
    }

    return ret;
}

static int ssl23_get_server_hello(SSL *s)
{
    char buf[8];
    unsigned char *p;
    int i;
    int n;

    n = ssl23_read_bytes(s, 7);

    if (n != 7)
        return (n);
    p = s->packet;

    memcpy(buf, p, n);

    if ((p[0] & 0x80) && (p[2] == SSL2_MT_SERVER_HELLO) &&
        (p[5] == 0x00) && (p[6] == 0x02)) {
#ifdef OPENSSL_NO_SSL2
        SSLerr(SSL_F_SSL23_GET_SERVER_HELLO, SSL_R_UNSUPPORTED_PROTOCOL);
        goto err;
#else
        /* we are talking sslv2 */
        /*
         * we need to clean up the SSLv3 setup and put in the sslv2 stuff.
         */
        int ch_len;

        if (s->options & SSL_OP_NO_SSLv2) {
            SSLerr(SSL_F_SSL23_GET_SERVER_HELLO, SSL_R_UNSUPPORTED_PROTOCOL);
            goto err;
        }
        if (s->s2 == NULL) {
            if (!ssl2_new(s))
                goto err;
        } else
            ssl2_clear(s);

        if (s->options & SSL_OP_NETSCAPE_CHALLENGE_BUG)
            ch_len = SSL2_CHALLENGE_LENGTH;
        else
            ch_len = SSL2_MAX_CHALLENGE_LENGTH;

        /* write out sslv2 challenge */
        /*
         * Note that ch_len must be <= SSL3_RANDOM_SIZE (32), because it is
         * one of SSL2_MAX_CHALLENGE_LENGTH (32) or SSL2_MAX_CHALLENGE_LENGTH
         * (16), but leave the check in for futurproofing
         */
        i = (SSL3_RANDOM_SIZE < ch_len)
            ? SSL3_RANDOM_SIZE : ch_len;
        s->s2->challenge_length = i;
        memcpy(s->s2->challenge,
               &(s->s3->client_random[SSL3_RANDOM_SIZE - i]), i);

        if (s->s3 != NULL)
            ssl3_free(s);

        if (!BUF_MEM_grow_clean(s->init_buf,
                                SSL2_MAX_RECORD_LENGTH_3_BYTE_HEADER)) {
            SSLerr(SSL_F_SSL23_GET_SERVER_HELLO, ERR_R_BUF_LIB);
            goto err;
        }

        s->state = SSL2_ST_GET_SERVER_HELLO_A;
        if (!(s->client_version == SSL2_VERSION))
            /*
             * use special padding (SSL 3.0 draft/RFC 2246, App. E.2)
             */
            s->s2->ssl2_rollback = 1;

        /*
         * setup the 7 bytes we have read so we get them from the sslv2
         * buffer
         */
        s->rstate = SSL_ST_READ_HEADER;
        s->packet_length = n;
        s->packet = &(s->s2->rbuf[0]);
        memcpy(s->packet, buf, n);
        s->s2->rbuf_left = n;
        s->s2->rbuf_offs = 0;

        /* we have already written one */
        s->s2->write_sequence = 1;

        s->method = SSLv2_client_method();
        s->handshake_func = s->method->ssl_connect;
#endif
    } else if (p[1] == SSL3_VERSION_MAJOR &&
               p[2] <= TLS1_2_VERSION_MINOR &&
               ((p[0] == SSL3_RT_HANDSHAKE && p[5] == SSL3_MT_SERVER_HELLO) ||
                (p[0] == SSL3_RT_ALERT && p[3] == 0 && p[4] == 2))) {
        /* we have sslv3 or tls1 (server hello or alert) */

#ifndef OPENSSL_NO_SSL3
        if ((p[2] == SSL3_VERSION_MINOR) && !(s->options & SSL_OP_NO_SSLv3)) {
# ifdef OPENSSL_FIPS
            if (FIPS_mode()) {
                SSLerr(SSL_F_SSL23_GET_SERVER_HELLO,
                       SSL_R_ONLY_TLS_ALLOWED_IN_FIPS_MODE);
                goto err;
            }
# endif
            s->version = SSL3_VERSION;
            s->method = SSLv3_client_method();
        } else
#endif
        if ((p[2] == TLS1_VERSION_MINOR) && !(s->options & SSL_OP_NO_TLSv1)) {
            s->version = TLS1_VERSION;
            s->method = TLSv1_client_method();
        } else if ((p[2] == TLS1_1_VERSION_MINOR) &&
                   !(s->options & SSL_OP_NO_TLSv1_1)) {
            s->version = TLS1_1_VERSION;
            s->method = TLSv1_1_client_method();
        } else if ((p[2] == TLS1_2_VERSION_MINOR) &&
                   !(s->options & SSL_OP_NO_TLSv1_2)) {
            s->version = TLS1_2_VERSION;
            s->method = TLSv1_2_client_method();
        } else {
            SSLerr(SSL_F_SSL23_GET_SERVER_HELLO, SSL_R_UNSUPPORTED_PROTOCOL);
            goto err;
        }

        s->session->ssl_version = s->version;

        /* ensure that TLS_MAX_VERSION is up-to-date */
        OPENSSL_assert(s->version <= TLS_MAX_VERSION);

        if (p[0] == SSL3_RT_ALERT && p[5] != SSL3_AL_WARNING) {
            /* fatal alert */

            void (*cb) (const SSL *ssl, int type, int val) = NULL;
            int j;

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

            i = p[5];
            if (cb != NULL) {
                j = (i << 8) | p[6];
                cb(s, SSL_CB_READ_ALERT, j);
            }

            if (s->msg_callback) {
                s->msg_callback(0, s->version, SSL3_RT_HEADER, p, 5, s,
                                s->msg_callback_arg);
                s->msg_callback(0, s->version, SSL3_RT_ALERT, p + 5, 2, s,
                                s->msg_callback_arg);
            }

            s->rwstate = SSL_NOTHING;
            SSLerr(SSL_F_SSL23_GET_SERVER_HELLO, SSL_AD_REASON_OFFSET + p[6]);
            goto err;
        }

        if (!ssl_init_wbio_buffer(s, 1))
            goto err;

        /* we are in this state */
        s->state = SSL3_ST_CR_SRVR_HELLO_A;

        /*
         * put the 7 bytes we have read into the input buffer for SSLv3
         */
        s->rstate = SSL_ST_READ_HEADER;
        s->packet_length = n;
        if (s->s3->rbuf.buf == NULL)
            if (!ssl3_setup_read_buffer(s))
                goto err;
        s->packet = &(s->s3->rbuf.buf[0]);
        memcpy(s->packet, buf, n);
        s->s3->rbuf.left = n;
        s->s3->rbuf.offset = 0;

        s->handshake_func = s->method->ssl_connect;
    } else {
        SSLerr(SSL_F_SSL23_GET_SERVER_HELLO, SSL_R_UNKNOWN_PROTOCOL);
        goto err;
    }
    s->init_num = 0;

    return (SSL_connect(s));
 err:
    return (-1);
}