programs/ssl/dtls_server.c - security/mbedtls - Rivoreo Source Code Repositories

 /*
  *  Simple DTLS server demonstration program
  *
  *  Copyright (C) 2014, Brainspark B.V.
  *
  *  This file is part of mbed TLS (https://polarssl.org)
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License along
  *  with this program; if not, write to the Free Software Foundation, Inc.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */

 #if !defined(POLARSSL_CONFIG_FILE)
 #include "polarssl/config.h"
 #else
 #include POLARSSL_CONFIG_FILE
 #endif

 #if defined(POLARSSL_PLATFORM_C)
 #include "polarssl/platform.h"
 #else
 #define polarssl_printf     printf
 #define polarssl_fprintf    fprintf
 #endif

 #if !defined(POLARSSL_SSL_SRV_C) || !defined(POLARSSL_SSL_PROTO_DTLS) ||    \
     !defined(POLARSSL_SSL_COOKIE_C) || !defined(POLARSSL_NET_C) ||          \
     !defined(POLARSSL_ENTROPY_C) || !defined(POLARSSL_CTR_DRBG_C) ||        \
     !defined(POLARSSL_X509_CRT_PARSE_C) || !defined(POLARSSL_RSA_C) ||      \
     !defined(POLARSSL_CERTS_C)

 #include <stdio.h>
 int main( void )
 {
     printf( "POLARSSL_SSL_SRV_C and/or POLARSSL_SSL_PROTO_DTLS and/or "
             "POLARSSL_SSL_COOKIE_C and/or POLARSSL_NET_C and/or "
             "POLARSSL_ENTROPY_C and/or POLARSSL_CTR_DRBG_C and/or "
             "POLARSSL_X509_CRT_PARSE_C and/or POLARSSL_RSA_C and/or "
             "POLARSSL_CERTS_C not defined.\n" );
     return( 0 );
 }
 #else

 #if defined(_WIN32)
 #include <windows.h>
 #endif

 #include <string.h>
 #include <stdlib.h>
 #include <stdio.h>

 #include "polarssl/entropy.h"
 #include "polarssl/ctr_drbg.h"
 #include "polarssl/certs.h"
 #include "polarssl/x509.h"
 #include "polarssl/ssl.h"
 #include "polarssl/ssl_cookie.h"
 #include "polarssl/net.h"
 #include "polarssl/error.h"
 #include "polarssl/debug.h"

 #if defined(POLARSSL_SSL_CACHE_C)
 #include "polarssl/ssl_cache.h"
 #endif

 #define READ_TIMEOUT_MS 10000   /* 5 seconds */
 #define DEBUG_LEVEL 0

 static void my_debug( void *ctx, int level, const char *str )
 {
     ((void) level);

     polarssl_fprintf( (FILE *) ctx, "%s", str );
     fflush(  (FILE *) ctx  );
 }

 int main( void )
 {
     int ret, len;
     int listen_fd;
     int client_fd = -1;
     unsigned char buf[1024];
     const char *pers = "dtls_server";
     unsigned char client_ip[16] = { 0 };
     ssl_cookie_ctx cookie_ctx;

     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
     ssl_context ssl;
     x509_crt srvcert;
     pk_context pkey;
 #if defined(POLARSSL_SSL_CACHE_C)
     ssl_cache_context cache;
 #endif

     memset( &ssl, 0, sizeof(ssl_context) );
     ssl_cookie_init( &cookie_ctx );
 #if defined(POLARSSL_SSL_CACHE_C)
     ssl_cache_init( &cache );
 #endif
     x509_crt_init( &srvcert );
     pk_init( &pkey );
     entropy_init( &entropy );

 #if defined(POLARSSL_DEBUG_C)
     debug_set_threshold( DEBUG_LEVEL );
 #endif

     /*
      * 1. Load the certificates and private RSA key
      */
     printf( "\n  . Loading the server cert. and key..." );
     fflush( stdout );

     /*
      * This demonstration program uses embedded test certificates.
      * Instead, you may want to use x509_crt_parse_file() to read the
      * server and CA certificates, as well as pk_parse_keyfile().
      */
     ret = x509_crt_parse( &srvcert, (const unsigned char *) test_srv_crt,
                           strlen( test_srv_crt ) );
     if( ret != 0 )
     {
         printf( " failed\n  !  x509_crt_parse returned %d\n\n", ret );
         goto exit;
     }

     ret = x509_crt_parse( &srvcert, (const unsigned char *) test_ca_list,
                           strlen( test_ca_list ) );
     if( ret != 0 )
     {
         printf( " failed\n  !  x509_crt_parse returned %d\n\n", ret );
         goto exit;
     }

     ret =  pk_parse_key( &pkey, (const unsigned char *) test_srv_key,
                          strlen( test_srv_key ), NULL, 0 );
     if( ret != 0 )
     {
         printf( " failed\n  !  pk_parse_key returned %d\n\n", ret );
         goto exit;
     }

     printf( " ok\n" );

     /*
      * 2. Setup the "listening" UDP socket
      */
     printf( "  . Bind on udp/*/4433 ..." );
     fflush( stdout );

     if( ( ret = net_bind( &listen_fd, NULL, 4433, NET_PROTO_UDP ) ) != 0 )
     {
         printf( " failed\n  ! net_bind returned %d\n\n", ret );
         goto exit;
     }

     printf( " ok\n" );

     /*
      * 3. Seed the RNG
      */
     printf( "  . Seeding the random number generator..." );
     fflush( stdout );

     if( ( ret = ctr_drbg_init( &ctr_drbg, entropy_func, &entropy,
                                (const unsigned char *) pers,
                                strlen( pers ) ) ) != 0 )
     {
         printf( " failed\n  ! ctr_drbg_init returned %d\n", ret );
         goto exit;
     }

     printf( " ok\n" );

     /*
      * 4. Setup stuff
      */
     printf( "  . Setting up the DTLS data..." );
     fflush( stdout );

     if( ( ret = ssl_init( &ssl ) ) != 0 )
     {
         printf( " failed\n  ! ssl_init returned %d\n\n", ret );
         goto exit;
     }

     ssl_set_endpoint( &ssl, SSL_IS_SERVER );
     ssl_set_transport( &ssl, SSL_TRANSPORT_DATAGRAM );
     ssl_set_authmode( &ssl, SSL_VERIFY_NONE );

     ssl_set_rng( &ssl, ctr_drbg_random, &ctr_drbg );
     ssl_set_dbg( &ssl, my_debug, stdout );

 #if defined(POLARSSL_SSL_CACHE_C)
     ssl_set_session_cache( &ssl, ssl_cache_get, &cache,
                                  ssl_cache_set, &cache );
 #endif

     ssl_set_ca_chain( &ssl, srvcert.next, NULL, NULL );
     if( ( ret = ssl_set_own_cert( &ssl, &srvcert, &pkey ) ) != 0 )
     {
         printf( " failed\n  ! ssl_set_own_cert returned %d\n\n", ret );
         goto exit;
     }

     if( ( ret = ssl_cookie_setup( &cookie_ctx,
                                   ctr_drbg_random, &ctr_drbg ) ) != 0 )
     {
         printf( " failed\n  ! ssl_cookie_setup returned %d\n\n", ret );
         goto exit;
     }

     ssl_set_dtls_cookies( &ssl, ssl_cookie_write, ssl_cookie_check,
                                &cookie_ctx );

     printf( " ok\n" );

 reset:
 #ifdef POLARSSL_ERROR_C
     if( ret != 0 )
     {
         char error_buf[100];
         polarssl_strerror( ret, error_buf, 100 );
         printf("Last error was: %d - %s\n\n", ret, error_buf );
     }
 #endif

     if( client_fd != -1 )
         net_close( client_fd );

     ssl_session_reset( &ssl );

     /*
      * 3. Wait until a client connects
      */
     client_fd = -1;

     printf( "  . Waiting for a remote connection ..." );
     fflush( stdout );

     if( ( ret = net_accept( listen_fd, &client_fd, client_ip ) ) != 0 )
     {
         printf( " failed\n  ! net_accept returned %d\n\n", ret );
         goto exit;
     }

     /* With UDP, bind_fd is hijacked by client_fd, so bind a new one */
     if( ( ret = net_bind( &listen_fd, NULL, 4433, NET_PROTO_UDP ) ) != 0 )
     {
         printf( " failed\n  ! net_bind returned -0x%x\n\n", -ret );
         goto exit;
     }

     /* For HelloVerifyRequest cookies */
     if( ( ret = ssl_set_client_transport_id( &ssl, client_ip,
                                            sizeof( client_ip ) ) ) != 0 )
     {
         printf( " failed\n  ! "
                 "ssl_set_client_tranport_id() returned -0x%x\n\n", -ret );
         goto exit;
     }

     ssl_set_bio_timeout( &ssl, &client_fd,
                          net_send, net_recv, net_recv_timeout,
                          READ_TIMEOUT_MS );

     printf( " ok\n" );

     /*
      * 5. Handshake
      */
     printf( "  . Performing the DTLS handshake..." );
     fflush( stdout );

     do ret = ssl_handshake( &ssl );
     while( ret == POLARSSL_ERR_NET_WANT_READ ||
            ret == POLARSSL_ERR_NET_WANT_WRITE );

     if( ret == POLARSSL_ERR_SSL_HELLO_VERIFY_REQUIRED )
     {
         printf( " hello verification requested\n" );
         ret = 0;
         goto reset;
     }
     else if( ret != 0 )
     {
         printf( " failed\n  ! ssl_handshake returned -0x%x\n\n", -ret );
         goto reset;
     }

     printf( " ok\n" );

     /*
      * 6. Read the echo Request
      */
     printf( "  < Read from client:" );
     fflush( stdout );

     len = sizeof( buf ) - 1;
     memset( buf, 0, sizeof( buf ) );

     do ret = ssl_read( &ssl, buf, len );
     while( ret == POLARSSL_ERR_NET_WANT_READ ||
            ret == POLARSSL_ERR_NET_WANT_WRITE );

     if( ret <= 0 )
     {
         switch( ret )
         {
             case POLARSSL_ERR_NET_TIMEOUT:
                 printf( " timeout\n\n" );
                 goto reset;

             case POLARSSL_ERR_SSL_PEER_CLOSE_NOTIFY:
                 printf( " connection was closed gracefully\n" );
                 ret = 0;
                 goto close_notify;

             default:
                 printf( " ssl_read returned -0x%x\n\n", -ret );
                 goto reset;
         }
     }

     len = ret;
     printf( " %d bytes read\n\n%s\n\n", len, buf );

     /*
      * 7. Write the 200 Response
      */
     printf( "  > Write to client:" );
     fflush( stdout );

     do ret = ssl_write( &ssl, buf, len );
     while( ret == POLARSSL_ERR_NET_WANT_READ ||
            ret == POLARSSL_ERR_NET_WANT_WRITE );

     if( ret < 0 )
     {
         printf( " failed\n  ! ssl_write returned %d\n\n", ret );
         goto exit;
     }

     len = ret;
     printf( " %d bytes written\n\n%s\n\n", len, buf );

     /*
      * 8. Done, cleanly close the connection
      */
 close_notify:
     printf( "  . Closing the connection..." );

     /* No error checking, the connection might be closed already */
     do ret = ssl_close_notify( &ssl );
     while( ret == POLARSSL_ERR_NET_WANT_WRITE );
     ret = 0;

     printf( " done\n" );

     goto reset;

     /*
      * Final clean-ups and exit
      */
 exit:

 #ifdef POLARSSL_ERROR_C
     if( ret != 0 )
     {
         char error_buf[100];
         polarssl_strerror( ret, error_buf, 100 );
         printf( "Last error was: %d - %s\n\n", ret, error_buf );
     }
 #endif

     if( client_fd != -1 )
         net_close( client_fd );

     x509_crt_free( &srvcert );
     pk_free( &pkey );
     ssl_free( &ssl );
     ssl_cookie_free( &cookie_ctx );
 #if defined(POLARSSL_SSL_CACHE_C)
     ssl_cache_free( &cache );
 #endif
     ctr_drbg_free( &ctr_drbg );
     entropy_free( &entropy );

 #if defined(_WIN32)
     printf( "  Press Enter to exit this program.\n" );
     fflush( stdout ); getchar();
 #endif

     /* Shell can not handle large exit numbers -> 1 for errors */
     if( ret < 0 )
         ret = 1;

     return( ret );
 }
 #endif /* POLARSSL_SSL_SRV_C && POLARSSL_SSL_PROTO_DTLS &&
           POLARSSL_SSL_COOKIE_C && POLARSSL_NET_C && POLARSSL_ENTROPY_C &&
           POLARSSL_CTR_DRBG_C && POLARSSL_X509_CRT_PARSE_C && POLARSSL_RSA_C
           && POLARSSL_CERTS_C */
	/*
	* Simple DTLS server demonstration program
	*
	* Copyright (C) 2014, Brainspark B.V.
	*
	* This file is part of mbed TLS (https://polarssl.org)
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License along
	* with this program; if not, write to the Free Software Foundation, Inc.,
	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	*/

	#if !defined(POLARSSL_CONFIG_FILE)
	#include "polarssl/config.h"
	#else
	#include POLARSSL_CONFIG_FILE
	#endif

	#if defined(POLARSSL_PLATFORM_C)
	#include "polarssl/platform.h"
	#else
	#define polarssl_printf printf
	#define polarssl_fprintf fprintf
	#endif

	#if !defined(POLARSSL_SSL_SRV_C) \|\| !defined(POLARSSL_SSL_PROTO_DTLS) \|\| \
	!defined(POLARSSL_SSL_COOKIE_C) \|\| !defined(POLARSSL_NET_C) \|\| \
	!defined(POLARSSL_ENTROPY_C) \|\| !defined(POLARSSL_CTR_DRBG_C) \|\| \
	!defined(POLARSSL_X509_CRT_PARSE_C) \|\| !defined(POLARSSL_RSA_C) \|\| \
	!defined(POLARSSL_CERTS_C)

	#include <stdio.h>
	int main( void )
	{
	printf( "POLARSSL_SSL_SRV_C and/or POLARSSL_SSL_PROTO_DTLS and/or "
	"POLARSSL_SSL_COOKIE_C and/or POLARSSL_NET_C and/or "
	"POLARSSL_ENTROPY_C and/or POLARSSL_CTR_DRBG_C and/or "
	"POLARSSL_X509_CRT_PARSE_C and/or POLARSSL_RSA_C and/or "
	"POLARSSL_CERTS_C not defined.\n" );
	return( 0 );
	}
	#else

	#if defined(_WIN32)
	#include <windows.h>
	#endif

	#include <string.h>
	#include <stdlib.h>
	#include <stdio.h>

	#include "polarssl/entropy.h"
	#include "polarssl/ctr_drbg.h"
	#include "polarssl/certs.h"
	#include "polarssl/x509.h"
	#include "polarssl/ssl.h"
	#include "polarssl/ssl_cookie.h"
	#include "polarssl/net.h"
	#include "polarssl/error.h"
	#include "polarssl/debug.h"

	#if defined(POLARSSL_SSL_CACHE_C)
	#include "polarssl/ssl_cache.h"
	#endif

	#define READ_TIMEOUT_MS 10000 /* 5 seconds */
	#define DEBUG_LEVEL 0

	static void my_debug( void ctx, int level, const char str )
	{
	((void) level);

	polarssl_fprintf( (FILE *) ctx, "%s", str );
	fflush( (FILE *) ctx );
	}

	int main( void )
	{
	int ret, len;
	int listen_fd;
	int client_fd = -1;
	unsigned char buf[1024];
	const char *pers = "dtls_server";
	unsigned char client_ip[16] = { 0 };
	ssl_cookie_ctx cookie_ctx;

	entropy_context entropy;
	ctr_drbg_context ctr_drbg;
	ssl_context ssl;
	x509_crt srvcert;
	pk_context pkey;
	#if defined(POLARSSL_SSL_CACHE_C)
	ssl_cache_context cache;
	#endif

	memset( &ssl, 0, sizeof(ssl_context) );
	ssl_cookie_init( &cookie_ctx );
	#if defined(POLARSSL_SSL_CACHE_C)
	ssl_cache_init( &cache );
	#endif
	x509_crt_init( &srvcert );
	pk_init( &pkey );
	entropy_init( &entropy );

	#if defined(POLARSSL_DEBUG_C)
	debug_set_threshold( DEBUG_LEVEL );
	#endif

	/*
	* 1. Load the certificates and private RSA key
	*/
	printf( "\n . Loading the server cert. and key..." );
	fflush( stdout );

	/*
	* This demonstration program uses embedded test certificates.
	* Instead, you may want to use x509_crt_parse_file() to read the
	* server and CA certificates, as well as pk_parse_keyfile().
	*/
	ret = x509_crt_parse( &srvcert, (const unsigned char *) test_srv_crt,
	strlen( test_srv_crt ) );
	if( ret != 0 )
	{
	printf( " failed\n ! x509_crt_parse returned %d\n\n", ret );
	goto exit;
	}

	ret = x509_crt_parse( &srvcert, (const unsigned char *) test_ca_list,
	strlen( test_ca_list ) );
	if( ret != 0 )
	{
	printf( " failed\n ! x509_crt_parse returned %d\n\n", ret );
	goto exit;
	}

	ret = pk_parse_key( &pkey, (const unsigned char *) test_srv_key,
	strlen( test_srv_key ), NULL, 0 );
	if( ret != 0 )
	{
	printf( " failed\n ! pk_parse_key returned %d\n\n", ret );
	goto exit;
	}

	printf( " ok\n" );

	/*
	* 2. Setup the "listening" UDP socket
	*/
	printf( " . Bind on udp/*/4433 ..." );
	fflush( stdout );

	if( ( ret = net_bind( &listen_fd, NULL, 4433, NET_PROTO_UDP ) ) != 0 )
	{
	printf( " failed\n ! net_bind returned %d\n\n", ret );
	goto exit;
	}

	printf( " ok\n" );

	/*
	* 3. Seed the RNG
	*/
	printf( " . Seeding the random number generator..." );
	fflush( stdout );

	if( ( ret = ctr_drbg_init( &ctr_drbg, entropy_func, &entropy,
	(const unsigned char *) pers,
	strlen( pers ) ) ) != 0 )
	{
	printf( " failed\n ! ctr_drbg_init returned %d\n", ret );
	goto exit;
	}

	printf( " ok\n" );

	/*
	* 4. Setup stuff
	*/
	printf( " . Setting up the DTLS data..." );
	fflush( stdout );

	if( ( ret = ssl_init( &ssl ) ) != 0 )
	{
	printf( " failed\n ! ssl_init returned %d\n\n", ret );
	goto exit;
	}

	ssl_set_endpoint( &ssl, SSL_IS_SERVER );
	ssl_set_transport( &ssl, SSL_TRANSPORT_DATAGRAM );
	ssl_set_authmode( &ssl, SSL_VERIFY_NONE );

	ssl_set_rng( &ssl, ctr_drbg_random, &ctr_drbg );
	ssl_set_dbg( &ssl, my_debug, stdout );

	#if defined(POLARSSL_SSL_CACHE_C)
	ssl_set_session_cache( &ssl, ssl_cache_get, &cache,
	ssl_cache_set, &cache );
	#endif

	ssl_set_ca_chain( &ssl, srvcert.next, NULL, NULL );
	if( ( ret = ssl_set_own_cert( &ssl, &srvcert, &pkey ) ) != 0 )
	{
	printf( " failed\n ! ssl_set_own_cert returned %d\n\n", ret );
	goto exit;
	}

	if( ( ret = ssl_cookie_setup( &cookie_ctx,
	ctr_drbg_random, &ctr_drbg ) ) != 0 )
	{
	printf( " failed\n ! ssl_cookie_setup returned %d\n\n", ret );
	goto exit;
	}

	ssl_set_dtls_cookies( &ssl, ssl_cookie_write, ssl_cookie_check,
	&cookie_ctx );

	printf( " ok\n" );

	reset:
	#ifdef POLARSSL_ERROR_C
	if( ret != 0 )
	{
	char error_buf[100];
	polarssl_strerror( ret, error_buf, 100 );
	printf("Last error was: %d - %s\n\n", ret, error_buf );
	}
	#endif

	if( client_fd != -1 )
	net_close( client_fd );

	ssl_session_reset( &ssl );

	/*
	* 3. Wait until a client connects
	*/
	client_fd = -1;

	printf( " . Waiting for a remote connection ..." );
	fflush( stdout );

	if( ( ret = net_accept( listen_fd, &client_fd, client_ip ) ) != 0 )
	{
	printf( " failed\n ! net_accept returned %d\n\n", ret );
	goto exit;
	}

	/* With UDP, bind_fd is hijacked by client_fd, so bind a new one */
	if( ( ret = net_bind( &listen_fd, NULL, 4433, NET_PROTO_UDP ) ) != 0 )
	{
	printf( " failed\n ! net_bind returned -0x%x\n\n", -ret );
	goto exit;
	}

	/* For HelloVerifyRequest cookies */
	if( ( ret = ssl_set_client_transport_id( &ssl, client_ip,
	sizeof( client_ip ) ) ) != 0 )
	{
	printf( " failed\n ! "
	"ssl_set_client_tranport_id() returned -0x%x\n\n", -ret );
	goto exit;
	}

	ssl_set_bio_timeout( &ssl, &client_fd,
	net_send, net_recv, net_recv_timeout,
	READ_TIMEOUT_MS );

	printf( " ok\n" );

	/*
	* 5. Handshake
	*/
	printf( " . Performing the DTLS handshake..." );
	fflush( stdout );

	do ret = ssl_handshake( &ssl );
	while( ret == POLARSSL_ERR_NET_WANT_READ \|\|
	ret == POLARSSL_ERR_NET_WANT_WRITE );

	if( ret == POLARSSL_ERR_SSL_HELLO_VERIFY_REQUIRED )
	{
	printf( " hello verification requested\n" );
	ret = 0;
	goto reset;
	}
	else if( ret != 0 )
	{
	printf( " failed\n ! ssl_handshake returned -0x%x\n\n", -ret );
	goto reset;
	}

	printf( " ok\n" );

	/*
	* 6. Read the echo Request
	*/
	printf( " < Read from client:" );
	fflush( stdout );

	len = sizeof( buf ) - 1;
	memset( buf, 0, sizeof( buf ) );

	do ret = ssl_read( &ssl, buf, len );
	while( ret == POLARSSL_ERR_NET_WANT_READ \|\|
	ret == POLARSSL_ERR_NET_WANT_WRITE );

	if( ret <= 0 )
	{
	switch( ret )
	{
	case POLARSSL_ERR_NET_TIMEOUT:
	printf( " timeout\n\n" );
	goto reset;

	case POLARSSL_ERR_SSL_PEER_CLOSE_NOTIFY:
	printf( " connection was closed gracefully\n" );
	ret = 0;
	goto close_notify;

	default:
	printf( " ssl_read returned -0x%x\n\n", -ret );
	goto reset;
	}
	}

	len = ret;
	printf( " %d bytes read\n\n%s\n\n", len, buf );

	/*
	* 7. Write the 200 Response
	*/
	printf( " > Write to client:" );
	fflush( stdout );

	do ret = ssl_write( &ssl, buf, len );
	while( ret == POLARSSL_ERR_NET_WANT_READ \|\|
	ret == POLARSSL_ERR_NET_WANT_WRITE );

	if( ret < 0 )
	{
	printf( " failed\n ! ssl_write returned %d\n\n", ret );
	goto exit;
	}

	len = ret;
	printf( " %d bytes written\n\n%s\n\n", len, buf );

	/*
	* 8. Done, cleanly close the connection
	*/
	close_notify:
	printf( " . Closing the connection..." );

	/* No error checking, the connection might be closed already */
	do ret = ssl_close_notify( &ssl );
	while( ret == POLARSSL_ERR_NET_WANT_WRITE );
	ret = 0;

	printf( " done\n" );

	goto reset;

	/*
	* Final clean-ups and exit
	*/
	exit:

	#ifdef POLARSSL_ERROR_C
	if( ret != 0 )
	{
	char error_buf[100];
	polarssl_strerror( ret, error_buf, 100 );
	printf( "Last error was: %d - %s\n\n", ret, error_buf );
	}
	#endif

	if( client_fd != -1 )
	net_close( client_fd );

	x509_crt_free( &srvcert );
	pk_free( &pkey );
	ssl_free( &ssl );
	ssl_cookie_free( &cookie_ctx );
	#if defined(POLARSSL_SSL_CACHE_C)
	ssl_cache_free( &cache );
	#endif
	ctr_drbg_free( &ctr_drbg );
	entropy_free( &entropy );

	#if defined(_WIN32)
	printf( " Press Enter to exit this program.\n" );
	fflush( stdout ); getchar();
	#endif

	/* Shell can not handle large exit numbers -> 1 for errors */
	if( ret < 0 )
	ret = 1;

	return( ret );
	}
	#endif /* POLARSSL_SSL_SRV_C && POLARSSL_SSL_PROTO_DTLS &&
	POLARSSL_SSL_COOKIE_C && POLARSSL_NET_C && POLARSSL_ENTROPY_C &&
	POLARSSL_CTR_DRBG_C && POLARSSL_X509_CRT_PARSE_C && POLARSSL_RSA_C
	&& POLARSSL_CERTS_C */