Ejemplo n.º 1
0
int main( int argc, char *argv[] )
{
    int ret = 0, len;
    mbedtls_net_context server_fd;
    unsigned char buf[1024];
#if defined(MBEDTLS_BASE64_C)
    unsigned char base[1024];
#endif
    char hostname[32];
    const char *pers = "ssl_mail_client";

    mbedtls_entropy_context entropy;
    mbedtls_ctr_drbg_context ctr_drbg;
    mbedtls_ssl_context ssl;
    mbedtls_ssl_config conf;
    mbedtls_x509_crt cacert;
    mbedtls_x509_crt clicert;
    mbedtls_pk_context pkey;
    int i;
    size_t n;
    char *p, *q;
    const int *list;

    /*
     * Make sure memory references are valid in case we exit early.
     */
    mbedtls_net_init( &server_fd );
    mbedtls_ssl_init( &ssl );
    mbedtls_ssl_config_init( &conf );
    memset( &buf, 0, sizeof( buf ) );
    mbedtls_x509_crt_init( &cacert );
    mbedtls_x509_crt_init( &clicert );
    mbedtls_pk_init( &pkey );
    mbedtls_ctr_drbg_init( &ctr_drbg );

    if( argc == 0 )
    {
    usage:
        mbedtls_printf( USAGE );

        list = mbedtls_ssl_list_ciphersuites();
        while( *list )
        {
            mbedtls_printf("    %s\n", mbedtls_ssl_get_ciphersuite_name( *list ) );
            list++;
        }
        mbedtls_printf("\n");
        goto exit;
    }

    opt.server_name         = DFL_SERVER_NAME;
    opt.server_port         = DFL_SERVER_PORT;
    opt.debug_level         = DFL_DEBUG_LEVEL;
    opt.authentication      = DFL_AUTHENTICATION;
    opt.mode                = DFL_MODE;
    opt.user_name           = DFL_USER_NAME;
    opt.user_pwd            = DFL_USER_PWD;
    opt.mail_from           = DFL_MAIL_FROM;
    opt.mail_to             = DFL_MAIL_TO;
    opt.ca_file             = DFL_CA_FILE;
    opt.crt_file            = DFL_CRT_FILE;
    opt.key_file            = DFL_KEY_FILE;
    opt.force_ciphersuite[0]= DFL_FORCE_CIPHER;

    for( i = 1; i < argc; i++ )
    {
        p = argv[i];
        if( ( q = strchr( p, '=' ) ) == NULL )
            goto usage;
        *q++ = '\0';

        if( strcmp( p, "server_name" ) == 0 )
            opt.server_name = q;
        else if( strcmp( p, "server_port" ) == 0 )
            opt.server_port = q;
        else if( strcmp( p, "debug_level" ) == 0 )
        {
            opt.debug_level = atoi( q );
            if( opt.debug_level < 0 || opt.debug_level > 65535 )
                goto usage;
        }
        else if( strcmp( p, "authentication" ) == 0 )
        {
            opt.authentication = atoi( q );
            if( opt.authentication < 0 || opt.authentication > 1 )
                goto usage;
        }
        else if( strcmp( p, "mode" ) == 0 )
        {
            opt.mode = atoi( q );
            if( opt.mode < 0 || opt.mode > 1 )
                goto usage;
        }
        else if( strcmp( p, "user_name" ) == 0 )
            opt.user_name = q;
        else if( strcmp( p, "user_pwd" ) == 0 )
            opt.user_pwd = q;
        else if( strcmp( p, "mail_from" ) == 0 )
            opt.mail_from = q;
        else if( strcmp( p, "mail_to" ) == 0 )
            opt.mail_to = q;
        else if( strcmp( p, "ca_file" ) == 0 )
            opt.ca_file = q;
        else if( strcmp( p, "crt_file" ) == 0 )
            opt.crt_file = q;
        else if( strcmp( p, "key_file" ) == 0 )
            opt.key_file = q;
        else if( strcmp( p, "force_ciphersuite" ) == 0 )
        {
            opt.force_ciphersuite[0] = -1;

            opt.force_ciphersuite[0] = mbedtls_ssl_get_ciphersuite_id( q );

            if( opt.force_ciphersuite[0] <= 0 )
                goto usage;

            opt.force_ciphersuite[1] = 0;
        }
        else
            goto usage;
    }

    /*
     * 0. Initialize the RNG and the session data
     */
    mbedtls_printf( "\n  . Seeding the random number generator..." );
    fflush( stdout );

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

    mbedtls_printf( " ok\n" );

    /*
     * 1.1. Load the trusted CA
     */
    mbedtls_printf( "  . Loading the CA root certificate ..." );
    fflush( stdout );

#if defined(MBEDTLS_FS_IO)
    if( strlen( opt.ca_file ) )
        ret = mbedtls_x509_crt_parse_file( &cacert, opt.ca_file );
    else
#endif
#if defined(MBEDTLS_CERTS_C)
        ret = mbedtls_x509_crt_parse( &cacert, (const unsigned char *) mbedtls_test_cas_pem,
                              mbedtls_test_cas_pem_len );
#else
    {
        ret = 1;
        mbedtls_printf("MBEDTLS_CERTS_C not defined.");
    }
#endif
    if( ret < 0 )
    {
        mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret );
        goto exit;
    }

    mbedtls_printf( " ok (%d skipped)\n", ret );

    /*
     * 1.2. Load own certificate and private key
     *
     * (can be skipped if client authentication is not required)
     */
    mbedtls_printf( "  . Loading the client cert. and key..." );
    fflush( stdout );

#if defined(MBEDTLS_FS_IO)
    if( strlen( opt.crt_file ) )
        ret = mbedtls_x509_crt_parse_file( &clicert, opt.crt_file );
    else
#endif
#if defined(MBEDTLS_CERTS_C)
        ret = mbedtls_x509_crt_parse( &clicert, (const unsigned char *) mbedtls_test_cli_crt,
                              mbedtls_test_cli_crt_len );
#else
    {
        ret = -1;
        mbedtls_printf("MBEDTLS_CERTS_C not defined.");
    }
#endif
    if( ret != 0 )
    {
        mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret );
        goto exit;
    }

#if defined(MBEDTLS_FS_IO)
    if( strlen( opt.key_file ) )
        ret = mbedtls_pk_parse_keyfile( &pkey, opt.key_file, "" );
    else
#endif
#if defined(MBEDTLS_CERTS_C) && defined(MBEDTLS_PEM_PARSE_C)
        ret = mbedtls_pk_parse_key( &pkey, (const unsigned char *) mbedtls_test_cli_key,
                mbedtls_test_cli_key_len, NULL, 0 );
#else
    {
        ret = -1;
        mbedtls_printf("MBEDTLS_CERTS_C or MBEDTLS_PEM_PARSE_C not defined.");
    }
#endif
    if( ret != 0 )
    {
        mbedtls_printf( " failed\n  !  mbedtls_pk_parse_key returned %d\n\n", ret );
        goto exit;
    }

    mbedtls_printf( " ok\n" );

    /*
     * 2. Start the connection
     */
    mbedtls_printf( "  . Connecting to tcp/%s/%s...", opt.server_name,
                                                opt.server_port );
    fflush( stdout );

    if( ( ret = mbedtls_net_connect( &server_fd, opt.server_name,
                             opt.server_port, MBEDTLS_NET_PROTO_TCP ) ) != 0 )
    {
        mbedtls_printf( " failed\n  ! mbedtls_net_connect returned %d\n\n", ret );
        goto exit;
    }

    mbedtls_printf( " ok\n" );

    /*
     * 3. Setup stuff
     */
    mbedtls_printf( "  . Setting up the SSL/TLS structure..." );
    fflush( stdout );

    if( ( ret = mbedtls_ssl_config_defaults( &conf,
                    MBEDTLS_SSL_IS_CLIENT,
                    MBEDTLS_SSL_TRANSPORT_STREAM,
                    MBEDTLS_SSL_PRESET_DEFAULT ) ) != 0 )
    {
        mbedtls_printf( " failed\n  ! mbedtls_ssl_config_defaults returned %d\n\n", ret );
        goto exit;
    }

    /* OPTIONAL is not optimal for security,
     * but makes interop easier in this simplified example */
    mbedtls_ssl_conf_authmode( &conf, MBEDTLS_SSL_VERIFY_OPTIONAL );

    mbedtls_ssl_conf_rng( &conf, mbedtls_ctr_drbg_random, &ctr_drbg );
    mbedtls_ssl_conf_dbg( &conf, my_debug, stdout );

    if( opt.force_ciphersuite[0] != DFL_FORCE_CIPHER )
        mbedtls_ssl_conf_ciphersuites( &conf, opt.force_ciphersuite );

    mbedtls_ssl_conf_ca_chain( &conf, &cacert, NULL );
    if( ( ret = mbedtls_ssl_conf_own_cert( &conf, &clicert, &pkey ) ) != 0 )
    {
        mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_own_cert returned %d\n\n", ret );
        goto exit;
    }

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

    if( ( ret = mbedtls_ssl_set_hostname( &ssl, opt.server_name ) ) != 0 )
    {
        mbedtls_printf( " failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n", ret );
        goto exit;
    }

    mbedtls_ssl_set_bio( &ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv, NULL );

    mbedtls_printf( " ok\n" );

    if( opt.mode == MODE_SSL_TLS )
    {
        if( do_handshake( &ssl ) != 0 )
            goto exit;

        mbedtls_printf( "  > Get header from server:" );
        fflush( stdout );

        ret = write_ssl_and_get_response( &ssl, buf, 0 );
        if( ret < 200 || ret > 299 )
        {
            mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        mbedtls_printf(" ok\n" );

        mbedtls_printf( "  > Write EHLO to server:" );
        fflush( stdout );

        gethostname( hostname, 32 );
        len = sprintf( (char *) buf, "EHLO %s\r\n", hostname );
        ret = write_ssl_and_get_response( &ssl, buf, len );
        if( ret < 200 || ret > 299 )
        {
            mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }
    }
    else
    {
        mbedtls_printf( "  > Get header from server:" );
        fflush( stdout );

        ret = write_and_get_response( &server_fd, buf, 0 );
        if( ret < 200 || ret > 299 )
        {
            mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        mbedtls_printf(" ok\n" );

        mbedtls_printf( "  > Write EHLO to server:" );
        fflush( stdout );

        gethostname( hostname, 32 );
        len = sprintf( (char *) buf, "EHLO %s\r\n", hostname );
        ret = write_and_get_response( &server_fd, buf, len );
        if( ret < 200 || ret > 299 )
        {
            mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        mbedtls_printf(" ok\n" );

        mbedtls_printf( "  > Write STARTTLS to server:" );
        fflush( stdout );

        gethostname( hostname, 32 );
        len = sprintf( (char *) buf, "STARTTLS\r\n" );
        ret = write_and_get_response( &server_fd, buf, len );
        if( ret < 200 || ret > 299 )
        {
            mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        mbedtls_printf(" ok\n" );

        if( do_handshake( &ssl ) != 0 )
            goto exit;
    }

#if defined(MBEDTLS_BASE64_C)
    if( opt.authentication )
    {
        mbedtls_printf( "  > Write AUTH LOGIN to server:" );
        fflush( stdout );

        len = sprintf( (char *) buf, "AUTH LOGIN\r\n" );
        ret = write_ssl_and_get_response( &ssl, buf, len );
        if( ret < 200 || ret > 399 )
        {
            mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        mbedtls_printf(" ok\n" );

        mbedtls_printf( "  > Write username to server: %s", opt.user_name );
        fflush( stdout );

        ret = mbedtls_base64_encode( base, sizeof( base ), &n, (const unsigned char *) opt.user_name,
                             strlen( opt.user_name ) );

        if( ret != 0 ) {
            mbedtls_printf( " failed\n  ! mbedtls_base64_encode returned %d\n\n", ret );
            goto exit;
        }
        len = sprintf( (char *) buf, "%s\r\n", base );
        ret = write_ssl_and_get_response( &ssl, buf, len );
        if( ret < 300 || ret > 399 )
        {
            mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        mbedtls_printf(" ok\n" );

        mbedtls_printf( "  > Write password to server: %s", opt.user_pwd );
        fflush( stdout );

        ret = mbedtls_base64_encode( base, sizeof( base ), &n, (const unsigned char *) opt.user_pwd,
                             strlen( opt.user_pwd ) );

        if( ret != 0 ) {
            mbedtls_printf( " failed\n  ! mbedtls_base64_encode returned %d\n\n", ret );
            goto exit;
        }
        len = sprintf( (char *) buf, "%s\r\n", base );
        ret = write_ssl_and_get_response( &ssl, buf, len );
        if( ret < 200 || ret > 399 )
        {
            mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        mbedtls_printf(" ok\n" );
    }
#endif

    mbedtls_printf( "  > Write MAIL FROM to server:" );
    fflush( stdout );

    len = sprintf( (char *) buf, "MAIL FROM:<%s>\r\n", opt.mail_from );
    ret = write_ssl_and_get_response( &ssl, buf, len );
    if( ret < 200 || ret > 299 )
    {
        mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
        goto exit;
    }

    mbedtls_printf(" ok\n" );

    mbedtls_printf( "  > Write RCPT TO to server:" );
    fflush( stdout );

    len = sprintf( (char *) buf, "RCPT TO:<%s>\r\n", opt.mail_to );
    ret = write_ssl_and_get_response( &ssl, buf, len );
    if( ret < 200 || ret > 299 )
    {
        mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
        goto exit;
    }

    mbedtls_printf(" ok\n" );

    mbedtls_printf( "  > Write DATA to server:" );
    fflush( stdout );

    len = sprintf( (char *) buf, "DATA\r\n" );
    ret = write_ssl_and_get_response( &ssl, buf, len );
    if( ret < 300 || ret > 399 )
    {
        mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
        goto exit;
    }

    mbedtls_printf(" ok\n" );

    mbedtls_printf( "  > Write content to server:" );
    fflush( stdout );

    len = sprintf( (char *) buf, "From: %s\r\nSubject: mbed TLS Test mail\r\n\r\n"
            "This is a simple test mail from the "
            "mbed TLS mail client example.\r\n"
            "\r\n"
            "Enjoy!", opt.mail_from );
    ret = write_ssl_data( &ssl, buf, len );

    len = sprintf( (char *) buf, "\r\n.\r\n");
    ret = write_ssl_and_get_response( &ssl, buf, len );
    if( ret < 200 || ret > 299 )
    {
        mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
        goto exit;
    }

    mbedtls_printf(" ok\n" );

    mbedtls_ssl_close_notify( &ssl );

exit:

    mbedtls_net_free( &server_fd );
    mbedtls_x509_crt_free( &clicert );
    mbedtls_x509_crt_free( &cacert );
    mbedtls_pk_free( &pkey );
    mbedtls_ssl_free( &ssl );
    mbedtls_ssl_config_free( &conf );
    mbedtls_ctr_drbg_free( &ctr_drbg );
    mbedtls_entropy_free( &entropy );

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

    return( ret );
}
Ejemplo n.º 2
0
int main( int argc, char *argv[] )
{
    int ret = 0, len, server_fd;
    unsigned char buf[1024];
#if defined(POLARSSL_BASE64_C)
    unsigned char base[1024];
#endif
    char hostname[32];
    const char *pers = "ssl_mail_client";

    entropy_context entropy;
    ctr_drbg_context ctr_drbg;
    ssl_context ssl;
    x509_crt cacert;
    x509_crt clicert;
    pk_context pkey;
    int i;
    size_t n;
    char *p, *q;
    const int *list;

    /*
     * Make sure memory references are valid in case we exit early.
     */
    server_fd = 0;
    memset( &ssl, 0, sizeof( ssl_context ) );
    x509_crt_init( &cacert );
    x509_crt_init( &clicert );
    pk_init( &pkey );

    if( argc == 0 )
    {
    usage:
        printf( USAGE );

        list = ssl_list_ciphersuites();
        while( *list )
        {
            printf("    %s\n", ssl_get_ciphersuite_name( *list ) );
            list++;
        }
        printf("\n");
        goto exit;
    }

    opt.server_name         = DFL_SERVER_NAME;
    opt.server_port         = DFL_SERVER_PORT;
    opt.debug_level         = DFL_DEBUG_LEVEL;
    opt.authentication      = DFL_AUTHENTICATION;
    opt.mode                = DFL_MODE;
    opt.user_name           = DFL_USER_NAME;
    opt.user_pwd            = DFL_USER_PWD;
    opt.mail_from           = DFL_MAIL_FROM;
    opt.mail_to             = DFL_MAIL_TO;
    opt.ca_file             = DFL_CA_FILE;
    opt.crt_file            = DFL_CRT_FILE;
    opt.key_file            = DFL_KEY_FILE;
    opt.force_ciphersuite[0]= DFL_FORCE_CIPHER;

    for( i = 1; i < argc; i++ )
    {
        p = argv[i];
        if( ( q = strchr( p, '=' ) ) == NULL )
            goto usage;
        *q++ = '\0';

        if( strcmp( p, "server_name" ) == 0 )
            opt.server_name = q;
        else if( strcmp( p, "server_port" ) == 0 )
        {
            opt.server_port = atoi( q );
            if( opt.server_port < 1 || opt.server_port > 65535 )
                goto usage;
        }
        else if( strcmp( p, "debug_level" ) == 0 )
        {
            opt.debug_level = atoi( q );
            if( opt.debug_level < 0 || opt.debug_level > 65535 )
                goto usage;
        }
        else if( strcmp( p, "authentication" ) == 0 )
        {
            opt.authentication = atoi( q );
            if( opt.authentication < 0 || opt.authentication > 1 )
                goto usage;
        }
        else if( strcmp( p, "mode" ) == 0 )
        {
            opt.mode = atoi( q );
            if( opt.mode < 0 || opt.mode > 1 )
                goto usage;
        }
        else if( strcmp( p, "user_name" ) == 0 )
            opt.user_name = q;
        else if( strcmp( p, "user_pwd" ) == 0 )
            opt.user_pwd = q;
        else if( strcmp( p, "mail_from" ) == 0 )
            opt.mail_from = q;
        else if( strcmp( p, "mail_to" ) == 0 )
            opt.mail_to = q;
        else if( strcmp( p, "ca_file" ) == 0 )
            opt.ca_file = q;
        else if( strcmp( p, "crt_file" ) == 0 )
            opt.crt_file = q;
        else if( strcmp( p, "key_file" ) == 0 )
            opt.key_file = q;
        else if( strcmp( p, "force_ciphersuite" ) == 0 )
        {
            opt.force_ciphersuite[0] = -1;

            opt.force_ciphersuite[0] = ssl_get_ciphersuite_id( q );

            if( opt.force_ciphersuite[0] <= 0 )
                goto usage;

            opt.force_ciphersuite[1] = 0;
        }
        else
            goto usage;
    }

    /*
     * 0. Initialize the RNG and the session data
     */
    printf( "\n  . Seeding the random number generator..." );
    fflush( stdout );

    entropy_init( &entropy );
    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" );

    /*
     * 1.1. Load the trusted CA
     */
    printf( "  . Loading the CA root certificate ..." );
    fflush( stdout );

#if defined(POLARSSL_FS_IO)
    if( strlen( opt.ca_file ) )
        ret = x509_crt_parse_file( &cacert, opt.ca_file );
    else
#endif
#if defined(POLARSSL_CERTS_C)
        ret = x509_crt_parse( &cacert, (const unsigned char *) test_ca_list,
                              strlen( test_ca_list ) );
#else
    {
        ret = 1;
        printf("POLARSSL_CERTS_C not defined.");
    }
#endif
    if( ret < 0 )
    {
        printf( " failed\n  !  x509_crt_parse returned %d\n\n", ret );
        goto exit;
    }

    printf( " ok (%d skipped)\n", ret );

    /*
     * 1.2. Load own certificate and private key
     *
     * (can be skipped if client authentication is not required)
     */
    printf( "  . Loading the client cert. and key..." );
    fflush( stdout );

#if defined(POLARSSL_FS_IO)
    if( strlen( opt.crt_file ) )
        ret = x509_crt_parse_file( &clicert, opt.crt_file );
    else
#endif
#if defined(POLARSSL_CERTS_C)
        ret = x509_crt_parse( &clicert, (const unsigned char *) test_cli_crt,
                              strlen( test_cli_crt ) );
#else
    {
        ret = -1;
        printf("POLARSSL_CERTS_C not defined.");
    }
#endif
    if( ret != 0 )
    {
        printf( " failed\n  !  x509_crt_parse returned %d\n\n", ret );
        goto exit;
    }

#if defined(POLARSSL_FS_IO)
    if( strlen( opt.key_file ) )
        ret = pk_parse_keyfile( &pkey, opt.key_file, "" );
    else
#endif
#if defined(POLARSSL_CERTS_C)
        ret = pk_parse_key( &pkey, (const unsigned char *) test_cli_key,
                strlen( test_cli_key ), NULL, 0 );
#else
    {
        ret = -1;
        printf("POLARSSL_CERTS_C not defined.");
    }
#endif
    if( ret != 0 )
    {
        printf( " failed\n  !  pk_parse_key returned %d\n\n", ret );
        goto exit;
    }

    printf( " ok\n" );

    /*
     * 2. Start the connection
     */
    printf( "  . Connecting to tcp/%s/%-4d...", opt.server_name,
                                                opt.server_port );
    fflush( stdout );

    if( ( ret = net_connect( &server_fd, opt.server_name,
                                         opt.server_port ) ) != 0 )
    {
        printf( " failed\n  ! net_connect returned %d\n\n", ret );
        goto exit;
    }

    printf( " ok\n" );

    /*
     * 3. Setup stuff
     */
    printf( "  . Setting up the SSL/TLS structure..." );
    fflush( stdout );

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

    printf( " ok\n" );

    ssl_set_endpoint( &ssl, SSL_IS_CLIENT );
    ssl_set_authmode( &ssl, SSL_VERIFY_OPTIONAL );

    ssl_set_rng( &ssl, ctr_drbg_random, &ctr_drbg );
    ssl_set_dbg( &ssl, my_debug, stdout );
    ssl_set_bio( &ssl, net_recv, &server_fd,
            net_send, &server_fd );

    if( opt.force_ciphersuite[0] != DFL_FORCE_CIPHER )
        ssl_set_ciphersuites( &ssl, opt.force_ciphersuite );

    ssl_set_ca_chain( &ssl, &cacert, NULL, opt.server_name );
    ssl_set_own_cert( &ssl, &clicert, &pkey );

#if defined(POLARSSL_SSL_SERVER_NAME_INDICATION)
    ssl_set_hostname( &ssl, opt.server_name );
#endif

    if( opt.mode == MODE_SSL_TLS )
    {
        if( do_handshake( &ssl, &opt ) != 0 )
            goto exit;

        printf( "  > Get header from server:" );
        fflush( stdout );

        ret = write_ssl_and_get_response( &ssl, buf, 0 );
        if( ret < 200 || ret > 299 )
        {
            printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        printf(" ok\n" );

        printf( "  > Write EHLO to server:" );
        fflush( stdout );

        gethostname( hostname, 32 );
        len = sprintf( (char *) buf, "EHLO %s\r\n", hostname );
        ret = write_ssl_and_get_response( &ssl, buf, len );
        if( ret < 200 || ret > 299 )
        {
            printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }
    }
    else
    {
        printf( "  > Get header from server:" );
        fflush( stdout );

        ret = write_and_get_response( server_fd, buf, 0 );
        if( ret < 200 || ret > 299 )
        {
            printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        printf(" ok\n" );

        printf( "  > Write EHLO to server:" );
        fflush( stdout );

        gethostname( hostname, 32 );
        len = sprintf( (char *) buf, "EHLO %s\r\n", hostname );
        ret = write_and_get_response( server_fd, buf, len );
        if( ret < 200 || ret > 299 )
        {
            printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        printf(" ok\n" );

        printf( "  > Write STARTTLS to server:" );
        fflush( stdout );

        gethostname( hostname, 32 );
        len = sprintf( (char *) buf, "STARTTLS\r\n" );
        ret = write_and_get_response( server_fd, buf, len );
        if( ret < 200 || ret > 299 )
        {
            printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        printf(" ok\n" );

        if( do_handshake( &ssl, &opt ) != 0 )
            goto exit;
    }

#if defined(POLARSSL_BASE64_C)
    if( opt.authentication )
    {
        printf( "  > Write AUTH LOGIN to server:" );
        fflush( stdout );

        len = sprintf( (char *) buf, "AUTH LOGIN\r\n" );
        ret = write_ssl_and_get_response( &ssl, buf, len );
        if( ret < 200 || ret > 399 )
        {
            printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        printf(" ok\n" );

        printf( "  > Write username to server: %s", opt.user_name );
        fflush( stdout );

        n = sizeof( buf );
        len = base64_encode( base, &n, (const unsigned char *) opt.user_name,
                             strlen( opt.user_name ) );
        len = sprintf( (char *) buf, "%s\r\n", base );
        ret = write_ssl_and_get_response( &ssl, buf, len );
        if( ret < 300 || ret > 399 )
        {
            printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        printf(" ok\n" );

        printf( "  > Write password to server: %s", opt.user_pwd );
        fflush( stdout );

        len = base64_encode( base, &n, (const unsigned char *) opt.user_pwd,
                             strlen( opt.user_pwd ) );
        len = sprintf( (char *) buf, "%s\r\n", base );
        ret = write_ssl_and_get_response( &ssl, buf, len );
        if( ret < 200 || ret > 399 )
        {
            printf( " failed\n  ! server responded with %d\n\n", ret );
            goto exit;
        }

        printf(" ok\n" );
    }
#endif

    printf( "  > Write MAIL FROM to server:" );
    fflush( stdout );

    len = sprintf( (char *) buf, "MAIL FROM:<%s>\r\n", opt.mail_from );
    ret = write_ssl_and_get_response( &ssl, buf, len );
    if( ret < 200 || ret > 299 )
    {
        printf( " failed\n  ! server responded with %d\n\n", ret );
        goto exit;
    }

    printf(" ok\n" );

    printf( "  > Write RCPT TO to server:" );
    fflush( stdout );

    len = sprintf( (char *) buf, "RCPT TO:<%s>\r\n", opt.mail_to );
    ret = write_ssl_and_get_response( &ssl, buf, len );
    if( ret < 200 || ret > 299 )
    {
        printf( " failed\n  ! server responded with %d\n\n", ret );
        goto exit;
    }

    printf(" ok\n" );

    printf( "  > Write DATA to server:" );
    fflush( stdout );

    len = sprintf( (char *) buf, "DATA\r\n" );
    ret = write_ssl_and_get_response( &ssl, buf, len );
    if( ret < 300 || ret > 399 )
    {
        printf( " failed\n  ! server responded with %d\n\n", ret );
        goto exit;
    }

    printf(" ok\n" );

    printf( "  > Write content to server:" );
    fflush( stdout );

    len = sprintf( (char *) buf, "From: %s\r\nSubject: PolarSSL Test mail\r\n\r\n"
            "This is a simple test mail from the "
            "PolarSSL mail client example.\r\n"
            "\r\n"
            "Enjoy!", opt.mail_from );
    ret = write_ssl_data( &ssl, buf, len );

    len = sprintf( (char *) buf, "\r\n.\r\n");
    ret = write_ssl_and_get_response( &ssl, buf, len );
    if( ret < 200 || ret > 299 )
    {
        printf( " failed\n  ! server responded with %d\n\n", ret );
        goto exit;
    }

    printf(" ok\n" );

    ssl_close_notify( &ssl );

exit:

    if( server_fd )
        net_close( server_fd );
    x509_crt_free( &clicert );
    x509_crt_free( &cacert );
    pk_free( &pkey );
    ssl_free( &ssl );
    entropy_free( &entropy );

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

    return( ret );
}