ssl/d1_clnt.c - boringssl - Git at Google

 /*
  * 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 <assert.h>
 #include <stdio.h>
 #include <string.h>

 #include <openssl/bn.h>
 #include <openssl/buf.h>
 #include <openssl/dh.h>
 #include <openssl/evp.h>
 #include <openssl/err.h>
 #include <openssl/md5.h>
 #include <openssl/mem.h>
 #include <openssl/obj.h>
 #include <openssl/rand.h>

 #include "internal.h"

 static int dtls1_get_hello_verify(SSL *s);

 int dtls1_connect(SSL *s) {
   BUF_MEM *buf = NULL;
   void (*cb)(const SSL *ssl, int type, int val) = NULL;
   int ret = -1;
   int new_state, state, skip = 0;

   assert(s->handshake_func == dtls1_connect);
   assert(!s->server);
   assert(SSL_IS_DTLS(s));

   ERR_clear_error();
   ERR_clear_system_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++;

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

     switch (s->state) {
       case SSL_ST_CONNECT:
         if (cb != NULL) {
           cb(s, SSL_CB_HANDSHAKE_START, 1);
         }

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

         if (!ssl_init_wbio_buffer(s, 0)) {
           ret = -1;
           goto end;
         }

         /* don't push the buffering BIO quite yet */

         s->state = SSL3_ST_CW_CLNT_HELLO_A;
         s->init_num = 0;
         s->d1->send_cookie = 0;
         s->hit = 0;
         break;

       case SSL3_ST_CW_CLNT_HELLO_A:
       case SSL3_ST_CW_CLNT_HELLO_B:
         s->shutdown = 0;

         /* every DTLS ClientHello resets Finished MAC */
         if (!ssl3_init_finished_mac(s)) {
           OPENSSL_PUT_ERROR(SSL, dtls1_connect, ERR_R_INTERNAL_ERROR);
           ret = -1;
           goto end;
         }

         dtls1_start_timer(s);
         ret = ssl3_send_client_hello(s);
         if (ret <= 0) {
           goto end;
         }

         if (s->d1->send_cookie) {
           s->state = SSL3_ST_CW_FLUSH;
           s->s3->tmp.next_state = SSL3_ST_CR_SRVR_HELLO_A;
         } else {
           s->state = DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A;
         }

         s->init_num = 0;
         /* turn on buffering for the next lot of output */
         if (s->bbio != s->wbio) {
           s->wbio = BIO_push(s->bbio, s->wbio);
         }

         break;

       case DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A:
       case DTLS1_ST_CR_HELLO_VERIFY_REQUEST_B:
         ret = dtls1_get_hello_verify(s);
         if (ret <= 0) {
           goto end;
         }
         if (s->d1->send_cookie) {
           /* start again, with a cookie */
           dtls1_stop_timer(s);
           s->state = SSL3_ST_CW_CLNT_HELLO_A;
         } else {
           s->state = SSL3_ST_CR_SRVR_HELLO_A;
         }
         s->init_num = 0;
         break;

       case SSL3_ST_CR_SRVR_HELLO_A:
       case SSL3_ST_CR_SRVR_HELLO_B:
         ret = ssl3_get_server_hello(s);
         if (ret <= 0) {
           goto end;
         }

         if (s->hit) {
           s->state = SSL3_ST_CR_FINISHED_A;
           if (s->tlsext_ticket_expected) {
             /* receive renewed session ticket */
             s->state = SSL3_ST_CR_SESSION_TICKET_A;
           }
         } else {
           s->state = SSL3_ST_CR_CERT_A;
         }
         s->init_num = 0;
         break;

       case SSL3_ST_CR_CERT_A:
       case SSL3_ST_CR_CERT_B:
         if (ssl_cipher_has_server_public_key(s->s3->tmp.new_cipher)) {
           ret = ssl3_get_server_certificate(s);
           if (ret <= 0) {
             goto end;
           }
           if (s->s3->tmp.certificate_status_expected) {
             s->state = SSL3_ST_CR_CERT_STATUS_A;
           } else {
             s->state = SSL3_ST_CR_KEY_EXCH_A;
           }
         } else {
           skip = 1;
           s->state = SSL3_ST_CR_KEY_EXCH_A;
         }
         s->init_num = 0;
         break;

       case SSL3_ST_CR_KEY_EXCH_A:
       case SSL3_ST_CR_KEY_EXCH_B:
         ret = ssl3_get_server_key_exchange(s);
         if (ret <= 0) {
           goto end;
         }
         s->state = SSL3_ST_CR_CERT_REQ_A;
         s->init_num = 0;
         break;

       case SSL3_ST_CR_CERT_REQ_A:
       case SSL3_ST_CR_CERT_REQ_B:
         ret = ssl3_get_certificate_request(s);
         if (ret <= 0) {
           goto end;
         }
         s->state = SSL3_ST_CR_SRVR_DONE_A;
         s->init_num = 0;
         break;

       case SSL3_ST_CR_SRVR_DONE_A:
       case SSL3_ST_CR_SRVR_DONE_B:
         ret = ssl3_get_server_done(s);
         if (ret <= 0) {
           goto end;
         }
         dtls1_stop_timer(s);
         if (s->s3->tmp.cert_req) {
           s->s3->tmp.next_state = SSL3_ST_CW_CERT_A;
         } else {
           s->s3->tmp.next_state = SSL3_ST_CW_KEY_EXCH_A;
         }
         s->init_num = 0;
         s->state = s->s3->tmp.next_state;
         break;

       case SSL3_ST_CW_CERT_A:
       case SSL3_ST_CW_CERT_B:
       case SSL3_ST_CW_CERT_C:
       case SSL3_ST_CW_CERT_D:
         dtls1_start_timer(s);
         ret = ssl3_send_client_certificate(s);
         if (ret <= 0) {
           goto end;
         }
         s->state = SSL3_ST_CW_KEY_EXCH_A;
         s->init_num = 0;
         break;

       case SSL3_ST_CW_KEY_EXCH_A:
       case SSL3_ST_CW_KEY_EXCH_B:
         dtls1_start_timer(s);
         ret = ssl3_send_client_key_exchange(s);
         if (ret <= 0) {
           goto end;
         }
         /* For TLS, cert_req is set to 2, so a cert chain
          * of nothing is sent, but no verify packet is sent */
         if (s->s3->tmp.cert_req == 1) {
           s->state = SSL3_ST_CW_CERT_VRFY_A;
         } else {
           s->state = SSL3_ST_CW_CHANGE_A;
           s->s3->change_cipher_spec = 0;
         }

         s->init_num = 0;
         break;

       case SSL3_ST_CW_CERT_VRFY_A:
       case SSL3_ST_CW_CERT_VRFY_B:
         dtls1_start_timer(s);
         ret = ssl3_send_cert_verify(s);
         if (ret <= 0) {
           goto end;
         }
         s->state = SSL3_ST_CW_CHANGE_A;
         s->init_num = 0;
         s->s3->change_cipher_spec = 0;
         break;

       case SSL3_ST_CW_CHANGE_A:
       case SSL3_ST_CW_CHANGE_B:
         if (!s->hit) {
           dtls1_start_timer(s);
         }
         ret = dtls1_send_change_cipher_spec(s, SSL3_ST_CW_CHANGE_A,
                                             SSL3_ST_CW_CHANGE_B);
         if (ret <= 0) {
           goto end;
         }

         s->state = SSL3_ST_CW_FINISHED_A;
         s->init_num = 0;

         s->session->cipher = s->s3->tmp.new_cipher;
         if (!s->enc_method->setup_key_block(s) ||
             !s->enc_method->change_cipher_state(
                 s, SSL3_CHANGE_CIPHER_CLIENT_WRITE)) {
           ret = -1;
           goto end;
         }

         dtls1_reset_seq_numbers(s, SSL3_CC_WRITE);
         break;

       case SSL3_ST_CW_FINISHED_A:
       case SSL3_ST_CW_FINISHED_B:
         if (!s->hit) {
           dtls1_start_timer(s);
         }

         ret =
             ssl3_send_finished(s, SSL3_ST_CW_FINISHED_A, SSL3_ST_CW_FINISHED_B,
                                s->enc_method->client_finished_label,
                                s->enc_method->client_finished_label_len);
         if (ret <= 0) {
           goto end;
         }
         s->state = SSL3_ST_CW_FLUSH;

         if (s->hit) {
           s->s3->tmp.next_state = SSL_ST_OK;
         } else {
           /* Allow NewSessionTicket if ticket expected */
           if (s->tlsext_ticket_expected) {
             s->s3->tmp.next_state = SSL3_ST_CR_SESSION_TICKET_A;
           } else {
             s->s3->tmp.next_state = SSL3_ST_CR_FINISHED_A;
           }
         }
         s->init_num = 0;
         break;

       case SSL3_ST_CR_SESSION_TICKET_A:
       case SSL3_ST_CR_SESSION_TICKET_B:
         ret = ssl3_get_new_session_ticket(s);
         if (ret <= 0) {
           goto end;
         }
         s->state = SSL3_ST_CR_FINISHED_A;
         s->init_num = 0;
         break;

       case SSL3_ST_CR_CERT_STATUS_A:
       case SSL3_ST_CR_CERT_STATUS_B:
         ret = ssl3_get_cert_status(s);
         if (ret <= 0) {
           goto end;
         }
         s->state = SSL3_ST_CR_KEY_EXCH_A;
         s->init_num = 0;
         break;

       case SSL3_ST_CR_FINISHED_A:
       case SSL3_ST_CR_FINISHED_B:
         s->d1->change_cipher_spec_ok = 1;
         ret =
             ssl3_get_finished(s, SSL3_ST_CR_FINISHED_A, SSL3_ST_CR_FINISHED_B);
         if (ret <= 0) {
           goto end;
         }
         dtls1_stop_timer(s);

         if (s->hit) {
           s->state = SSL3_ST_CW_CHANGE_A;
         } else {
           s->state = SSL_ST_OK;
         }

         s->init_num = 0;
         break;

       case SSL3_ST_CW_FLUSH:
         s->rwstate = SSL_WRITING;
         if (BIO_flush(s->wbio) <= 0) {
           ret = -1;
           goto end;
         }
         s->rwstate = SSL_NOTHING;
         s->state = s->s3->tmp.next_state;
         break;

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

         /* Remove write buffering now. */
         ssl_free_wbio_buffer(s);

         s->init_num = 0;
         s->s3->initial_handshake_complete = 1;

         ssl_update_cache(s, SSL_SESS_CACHE_CLIENT);

         ret = 1;

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

         /* done with handshaking */
         s->d1->handshake_read_seq = 0;
         s->d1->next_handshake_write_seq = 0;
         goto end;

       default:
         OPENSSL_PUT_ERROR(SSL, dtls1_connect, SSL_R_UNKNOWN_STATE);
         ret = -1;
         goto end;
     }

     /* did we do anything? */
     if (!s->s3->tmp.reuse_message && !skip) {
       if ((cb != NULL) && (s->state != state)) {
         new_state = s->state;
         s->state = state;
         cb(s, SSL_CB_CONNECT_LOOP, 1);
         s->state = new_state;
       }
     }
     skip = 0;
   }

 end:
   s->in_handshake--;

   BUF_MEM_free(buf);
   if (cb != NULL) {
     cb(s, SSL_CB_CONNECT_EXIT, ret);
   }
   return ret;
 }

 static int dtls1_get_hello_verify(SSL *s) {
   long n;
   int al, ok = 0;
   CBS hello_verify_request, cookie;
   uint16_t server_version;

   n = s->method->ssl_get_message(
       s, DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A, DTLS1_ST_CR_HELLO_VERIFY_REQUEST_B,
       -1,
       /* Use the same maximum size as ssl3_get_server_hello. */
       20000, ssl_hash_message, &ok);

   if (!ok) {
     return n;
   }

   if (s->s3->tmp.message_type != DTLS1_MT_HELLO_VERIFY_REQUEST) {
     s->d1->send_cookie = 0;
     s->s3->tmp.reuse_message = 1;
     return 1;
   }

   CBS_init(&hello_verify_request, s->init_msg, n);

   if (!CBS_get_u16(&hello_verify_request, &server_version) ||
       !CBS_get_u8_length_prefixed(&hello_verify_request, &cookie) ||
       CBS_len(&hello_verify_request) != 0) {
     al = SSL_AD_DECODE_ERROR;
     OPENSSL_PUT_ERROR(SSL, dtls1_get_hello_verify, SSL_R_DECODE_ERROR);
     goto f_err;
   }

   if (CBS_len(&cookie) > sizeof(s->d1->cookie)) {
     al = SSL_AD_ILLEGAL_PARAMETER;
     goto f_err;
   }

   memcpy(s->d1->cookie, CBS_data(&cookie), CBS_len(&cookie));
   s->d1->cookie_len = CBS_len(&cookie);

   s->d1->send_cookie = 1;
   return 1;

 f_err:
   ssl3_send_alert(s, SSL3_AL_FATAL, al);
   return -1;
 }
	/*
	* 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 <assert.h>
	#include <stdio.h>
	#include <string.h>

	#include <openssl/bn.h>
	#include <openssl/buf.h>
	#include <openssl/dh.h>
	#include <openssl/evp.h>
	#include <openssl/err.h>
	#include <openssl/md5.h>
	#include <openssl/mem.h>
	#include <openssl/obj.h>
	#include <openssl/rand.h>

	#include "internal.h"

	static int dtls1_get_hello_verify(SSL *s);

	int dtls1_connect(SSL *s) {
	BUF_MEM *buf = NULL;
	void (cb)(const SSL ssl, int type, int val) = NULL;
	int ret = -1;
	int new_state, state, skip = 0;

	assert(s->handshake_func == dtls1_connect);
	assert(!s->server);
	assert(SSL_IS_DTLS(s));

	ERR_clear_error();
	ERR_clear_system_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++;

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

	switch (s->state) {
	case SSL_ST_CONNECT:
	if (cb != NULL) {
	cb(s, SSL_CB_HANDSHAKE_START, 1);
	}

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

	if (!ssl_init_wbio_buffer(s, 0)) {
	ret = -1;
	goto end;
	}

	/* don't push the buffering BIO quite yet */

	s->state = SSL3_ST_CW_CLNT_HELLO_A;
	s->init_num = 0;
	s->d1->send_cookie = 0;
	s->hit = 0;
	break;

	case SSL3_ST_CW_CLNT_HELLO_A:
	case SSL3_ST_CW_CLNT_HELLO_B:
	s->shutdown = 0;

	/* every DTLS ClientHello resets Finished MAC */
	if (!ssl3_init_finished_mac(s)) {
	OPENSSL_PUT_ERROR(SSL, dtls1_connect, ERR_R_INTERNAL_ERROR);
	ret = -1;
	goto end;
	}

	dtls1_start_timer(s);
	ret = ssl3_send_client_hello(s);
	if (ret <= 0) {
	goto end;
	}

	if (s->d1->send_cookie) {
	s->state = SSL3_ST_CW_FLUSH;
	s->s3->tmp.next_state = SSL3_ST_CR_SRVR_HELLO_A;
	} else {
	s->state = DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A;
	}

	s->init_num = 0;
	/* turn on buffering for the next lot of output */
	if (s->bbio != s->wbio) {
	s->wbio = BIO_push(s->bbio, s->wbio);
	}

	break;

	case DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A:
	case DTLS1_ST_CR_HELLO_VERIFY_REQUEST_B:
	ret = dtls1_get_hello_verify(s);
	if (ret <= 0) {
	goto end;
	}
	if (s->d1->send_cookie) {
	/* start again, with a cookie */
	dtls1_stop_timer(s);
	s->state = SSL3_ST_CW_CLNT_HELLO_A;
	} else {
	s->state = SSL3_ST_CR_SRVR_HELLO_A;
	}
	s->init_num = 0;
	break;

	case SSL3_ST_CR_SRVR_HELLO_A:
	case SSL3_ST_CR_SRVR_HELLO_B:
	ret = ssl3_get_server_hello(s);
	if (ret <= 0) {
	goto end;
	}

	if (s->hit) {
	s->state = SSL3_ST_CR_FINISHED_A;
	if (s->tlsext_ticket_expected) {
	/* receive renewed session ticket */
	s->state = SSL3_ST_CR_SESSION_TICKET_A;
	}
	} else {
	s->state = SSL3_ST_CR_CERT_A;
	}
	s->init_num = 0;
	break;

	case SSL3_ST_CR_CERT_A:
	case SSL3_ST_CR_CERT_B:
	if (ssl_cipher_has_server_public_key(s->s3->tmp.new_cipher)) {
	ret = ssl3_get_server_certificate(s);
	if (ret <= 0) {
	goto end;
	}
	if (s->s3->tmp.certificate_status_expected) {
	s->state = SSL3_ST_CR_CERT_STATUS_A;
	} else {
	s->state = SSL3_ST_CR_KEY_EXCH_A;
	}
	} else {
	skip = 1;
	s->state = SSL3_ST_CR_KEY_EXCH_A;
	}
	s->init_num = 0;
	break;

	case SSL3_ST_CR_KEY_EXCH_A:
	case SSL3_ST_CR_KEY_EXCH_B:
	ret = ssl3_get_server_key_exchange(s);
	if (ret <= 0) {
	goto end;
	}
	s->state = SSL3_ST_CR_CERT_REQ_A;
	s->init_num = 0;
	break;

	case SSL3_ST_CR_CERT_REQ_A:
	case SSL3_ST_CR_CERT_REQ_B:
	ret = ssl3_get_certificate_request(s);
	if (ret <= 0) {
	goto end;
	}
	s->state = SSL3_ST_CR_SRVR_DONE_A;
	s->init_num = 0;
	break;

	case SSL3_ST_CR_SRVR_DONE_A:
	case SSL3_ST_CR_SRVR_DONE_B:
	ret = ssl3_get_server_done(s);
	if (ret <= 0) {
	goto end;
	}
	dtls1_stop_timer(s);
	if (s->s3->tmp.cert_req) {
	s->s3->tmp.next_state = SSL3_ST_CW_CERT_A;
	} else {
	s->s3->tmp.next_state = SSL3_ST_CW_KEY_EXCH_A;
	}
	s->init_num = 0;
	s->state = s->s3->tmp.next_state;
	break;

	case SSL3_ST_CW_CERT_A:
	case SSL3_ST_CW_CERT_B:
	case SSL3_ST_CW_CERT_C:
	case SSL3_ST_CW_CERT_D:
	dtls1_start_timer(s);
	ret = ssl3_send_client_certificate(s);
	if (ret <= 0) {
	goto end;
	}
	s->state = SSL3_ST_CW_KEY_EXCH_A;
	s->init_num = 0;
	break;

	case SSL3_ST_CW_KEY_EXCH_A:
	case SSL3_ST_CW_KEY_EXCH_B:
	dtls1_start_timer(s);
	ret = ssl3_send_client_key_exchange(s);
	if (ret <= 0) {
	goto end;
	}
	/* For TLS, cert_req is set to 2, so a cert chain
	* of nothing is sent, but no verify packet is sent */
	if (s->s3->tmp.cert_req == 1) {
	s->state = SSL3_ST_CW_CERT_VRFY_A;
	} else {
	s->state = SSL3_ST_CW_CHANGE_A;
	s->s3->change_cipher_spec = 0;
	}

	s->init_num = 0;
	break;

	case SSL3_ST_CW_CERT_VRFY_A:
	case SSL3_ST_CW_CERT_VRFY_B:
	dtls1_start_timer(s);
	ret = ssl3_send_cert_verify(s);
	if (ret <= 0) {
	goto end;
	}
	s->state = SSL3_ST_CW_CHANGE_A;
	s->init_num = 0;
	s->s3->change_cipher_spec = 0;
	break;

	case SSL3_ST_CW_CHANGE_A:
	case SSL3_ST_CW_CHANGE_B:
	if (!s->hit) {
	dtls1_start_timer(s);
	}
	ret = dtls1_send_change_cipher_spec(s, SSL3_ST_CW_CHANGE_A,
	SSL3_ST_CW_CHANGE_B);
	if (ret <= 0) {
	goto end;
	}

	s->state = SSL3_ST_CW_FINISHED_A;
	s->init_num = 0;

	s->session->cipher = s->s3->tmp.new_cipher;
	if (!s->enc_method->setup_key_block(s) \|\|
	!s->enc_method->change_cipher_state(
	s, SSL3_CHANGE_CIPHER_CLIENT_WRITE)) {
	ret = -1;
	goto end;
	}

	dtls1_reset_seq_numbers(s, SSL3_CC_WRITE);
	break;

	case SSL3_ST_CW_FINISHED_A:
	case SSL3_ST_CW_FINISHED_B:
	if (!s->hit) {
	dtls1_start_timer(s);
	}

	ret =
	ssl3_send_finished(s, SSL3_ST_CW_FINISHED_A, SSL3_ST_CW_FINISHED_B,
	s->enc_method->client_finished_label,
	s->enc_method->client_finished_label_len);
	if (ret <= 0) {
	goto end;
	}
	s->state = SSL3_ST_CW_FLUSH;

	if (s->hit) {
	s->s3->tmp.next_state = SSL_ST_OK;
	} else {
	/* Allow NewSessionTicket if ticket expected */
	if (s->tlsext_ticket_expected) {
	s->s3->tmp.next_state = SSL3_ST_CR_SESSION_TICKET_A;
	} else {
	s->s3->tmp.next_state = SSL3_ST_CR_FINISHED_A;
	}
	}
	s->init_num = 0;
	break;

	case SSL3_ST_CR_SESSION_TICKET_A:
	case SSL3_ST_CR_SESSION_TICKET_B:
	ret = ssl3_get_new_session_ticket(s);
	if (ret <= 0) {
	goto end;
	}
	s->state = SSL3_ST_CR_FINISHED_A;
	s->init_num = 0;
	break;

	case SSL3_ST_CR_CERT_STATUS_A:
	case SSL3_ST_CR_CERT_STATUS_B:
	ret = ssl3_get_cert_status(s);
	if (ret <= 0) {
	goto end;
	}
	s->state = SSL3_ST_CR_KEY_EXCH_A;
	s->init_num = 0;
	break;

	case SSL3_ST_CR_FINISHED_A:
	case SSL3_ST_CR_FINISHED_B:
	s->d1->change_cipher_spec_ok = 1;
	ret =
	ssl3_get_finished(s, SSL3_ST_CR_FINISHED_A, SSL3_ST_CR_FINISHED_B);
	if (ret <= 0) {
	goto end;
	}
	dtls1_stop_timer(s);

	if (s->hit) {
	s->state = SSL3_ST_CW_CHANGE_A;
	} else {
	s->state = SSL_ST_OK;
	}

	s->init_num = 0;
	break;

	case SSL3_ST_CW_FLUSH:
	s->rwstate = SSL_WRITING;
	if (BIO_flush(s->wbio) <= 0) {
	ret = -1;
	goto end;
	}
	s->rwstate = SSL_NOTHING;
	s->state = s->s3->tmp.next_state;
	break;

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

	/* Remove write buffering now. */
	ssl_free_wbio_buffer(s);

	s->init_num = 0;
	s->s3->initial_handshake_complete = 1;

	ssl_update_cache(s, SSL_SESS_CACHE_CLIENT);

	ret = 1;

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

	/* done with handshaking */
	s->d1->handshake_read_seq = 0;
	s->d1->next_handshake_write_seq = 0;
	goto end;

	default:
	OPENSSL_PUT_ERROR(SSL, dtls1_connect, SSL_R_UNKNOWN_STATE);
	ret = -1;
	goto end;
	}

	/* did we do anything? */
	if (!s->s3->tmp.reuse_message && !skip) {
	if ((cb != NULL) && (s->state != state)) {
	new_state = s->state;
	s->state = state;
	cb(s, SSL_CB_CONNECT_LOOP, 1);
	s->state = new_state;
	}
	}
	skip = 0;
	}

	end:
	s->in_handshake--;

	BUF_MEM_free(buf);
	if (cb != NULL) {
	cb(s, SSL_CB_CONNECT_EXIT, ret);
	}
	return ret;
	}

	static int dtls1_get_hello_verify(SSL *s) {
	long n;
	int al, ok = 0;
	CBS hello_verify_request, cookie;
	uint16_t server_version;

	n = s->method->ssl_get_message(
	s, DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A, DTLS1_ST_CR_HELLO_VERIFY_REQUEST_B,
	-1,
	/* Use the same maximum size as ssl3_get_server_hello. */
	20000, ssl_hash_message, &ok);

	if (!ok) {
	return n;
	}

	if (s->s3->tmp.message_type != DTLS1_MT_HELLO_VERIFY_REQUEST) {
	s->d1->send_cookie = 0;
	s->s3->tmp.reuse_message = 1;
	return 1;
	}

	CBS_init(&hello_verify_request, s->init_msg, n);

	if (!CBS_get_u16(&hello_verify_request, &server_version) \|\|
	!CBS_get_u8_length_prefixed(&hello_verify_request, &cookie) \|\|
	CBS_len(&hello_verify_request) != 0) {
	al = SSL_AD_DECODE_ERROR;
	OPENSSL_PUT_ERROR(SSL, dtls1_get_hello_verify, SSL_R_DECODE_ERROR);
	goto f_err;
	}

	if (CBS_len(&cookie) > sizeof(s->d1->cookie)) {
	al = SSL_AD_ILLEGAL_PARAMETER;
	goto f_err;
	}

	memcpy(s->d1->cookie, CBS_data(&cookie), CBS_len(&cookie));
	s->d1->cookie_len = CBS_len(&cookie);

	s->d1->send_cookie = 1;
	return 1;

	f_err:
	ssl3_send_alert(s, SSL3_AL_FATAL, al);
	return -1;
	}