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
	if (ver == SSL3_VERSION)
		return(SSLv3_client_method());
	else 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;
	ssl_set_client_disabled(s);
	ciphers = SSL_get_ciphers(s);
	for (i = 0; i < sk_SSL_CIPHER_num(ciphers); i++)
		{
		cipher = sk_SSL_CIPHER_value(ciphers, i);
		if (ssl_cipher_disabled(s, cipher, SSL_SECOP_CIPHER_SUPPORTED))
			continue;
		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 && !ssl_security(s, SSL_SECOP_SSL2_COMPAT, 0, 0, NULL))
		ssl2_compat = 0;
	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->custom_cli_ext_records_count != 0)
			ssl2_compat = 0;
		}
#endif

	buf=(unsigned char *)s->init_buf->data;
	if (s->state == SSL23_ST_CW_CLNT_HELLO_A)
		{
#if 0
		/* don't reuse session-id's */
		if (!ssl_get_new_session(s,0))
			{
			return(-1);
			}
#endif

		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) */
#if 0
			s->session->session_id_length=0;
#endif
			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 (!ssl_allow_compression(s) || !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) */

		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 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;
			}

		if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL))
			{
			SSLerr(SSL_F_SSL23_GET_SERVER_HELLO,SSL_R_VERSION_TOO_LOW);
			goto err;
			}

		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;

	/* Since, if we are sending a ssl23 client hello, we are not
	 * reusing a session-id */
	if (!ssl_get_new_session(s,0))
		goto err;

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