- Added the ssl_mail_client example application

ChangeLog

@@ -11,6 +11,7 @@ Features
      error codes and their description.
    * Added mpi_get_bit() and mpi_set_bit() individual bit setter/getter
      functions.
+   * Added ssl_mail_client and ssl_fork_server as example programs.
 
 Changes
    * Major argument / variable rewrite. Introduced use of size_t

programs/Makefile

@@ -17,7 +17,7 @@ APPS =	aes/aescrypt2	aes/crypt_and_hash	\
 	pkey/rsa_sign_pss	pkey/rsa_verify_pss \
 	ssl/ssl_client1		ssl/ssl_client2		\
 	ssl/ssl_server		ssl/ssl_fork_server	\
-	random/gen_random						\
+	ssl/ssl_mail_client	random/gen_random	\
 	test/ssl_cert_test	test/benchmark		\
 	test/selftest		test/ssl_test		\
 	x509/cert_app		x509/crl_app
@@ -110,6 +110,10 @@ ssl/ssl_fork_server: ssl/ssl_fork_server.c ../library/libpolarssl.a
 	echo   "  CC    ssl/ssl_fork_server.c"
 	$(CC) $(CFLAGS) $(OFLAGS) ssl/ssl_fork_server.c   $(LDFLAGS) -o $@
 
+ssl/ssl_mail_client: ssl/ssl_mail_client.c ../library/libpolarssl.a
+	echo   "  CC    ssl/ssl_mail_client.c"
+	$(CC) $(CFLAGS) $(OFLAGS) ssl/ssl_mail_client.c   $(LDFLAGS) -o $@
+
 test/ssl_cert_test: test/ssl_cert_test.c ../library/libpolarssl.a
 	echo   "  CC    test/ssl_cert_test.c"
 	$(CC) $(CFLAGS) $(OFLAGS) test/ssl_cert_test.c   $(LDFLAGS) -o $@

programs/ssl/CMakeLists.txt

@@ -18,6 +18,9 @@ target_link_libraries(ssl_server ${libs})
 add_executable(ssl_fork_server ssl_fork_server.c)
 target_link_libraries(ssl_fork_server ${libs})
 
-INSTALL(TARGETS ssl_client1 ssl_client2 ssl_server ssl_fork_server
+add_executable(ssl_mail_client ssl_mail_client.c)
+target_link_libraries(ssl_mail_client ${libs})
+
+INSTALL(TARGETS ssl_client1 ssl_client2 ssl_server ssl_fork_server ssl_mail_client
         DESTINATION "bin"
         PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)

programs/ssl/ssl_mail_client.c

@@ -0,0 +1,719 @@
+/*
+ *  SSL client for SMTP servers
+ *
+ *  Copyright (C) 2006-2010, Brainspark B.V.
+ *
+ *  This file is part of PolarSSL (http://www.polarssl.org)
+ *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
+ *
+ *  All rights reserved.
+ *
+ *  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.
+ */
+
+#ifndef _CRT_SECURE_NO_DEPRECATE
+#define _CRT_SECURE_NO_DEPRECATE 1
+#endif
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "polarssl/base64.h"
+#include "polarssl/error.h"
+#include "polarssl/net.h"
+#include "polarssl/ssl.h"
+#include "polarssl/havege.h"
+#include "polarssl/certs.h"
+#include "polarssl/x509.h"
+
+#define DFL_SERVER_NAME         "localhost"
+#define DFL_SERVER_PORT         465
+#define DFL_USER_NAME           "user"
+#define DFL_USER_PWD            "password"
+#define DFL_MAIL_FROM           ""
+#define DFL_MAIL_TO             ""
+#define DFL_DEBUG_LEVEL         0
+#define DFL_CRT_FILE            ""
+#define DFL_KEY_FILE            ""
+#define DFL_FORCE_CIPHER        0
+#define DFL_MODE                0
+#define DFL_AUTHENTICATION      0
+
+#define MODE_SSL_TLS            0
+#define MODE_STARTTLS           0
+
+/*
+ * global options
+ */
+struct options
+{
+    char *server_name;          /* hostname of the server (client only)     */
+    int server_port;            /* port on which the ssl service runs       */
+    int debug_level;            /* level of debugging                       */
+    int authentication;         /* if authentication is required            */
+    int mode;                   /* SSL/TLS (0) or STARTTLS (1)              */
+    char *user_name;            /* username to use for authentication       */
+    char *user_pwd;             /* password to use for authentication       */
+    char *mail_from;            /* E-Mail address to use as sender          */
+    char *mail_to;              /* E-Mail address to use as recipient       */
+    char *crt_file;             /* the file with the client certificate     */
+    char *key_file;             /* the file with the client key             */
+    int force_ciphersuite[2];   /* protocol/ciphersuite to use, or all      */
+} opt;
+
+void my_debug( void *ctx, int level, const char *str )
+{
+    if( level < opt.debug_level )
+    {
+        fprintf( (FILE *) ctx, "%s", str );
+        fflush(  (FILE *) ctx  );
+    }
+}
+
+int do_handshake( ssl_context *ssl, struct options *opt )
+{
+    int ret;
+    unsigned char buf[1024];
+
+    /*
+     * 4. Handshake
+     */
+    printf( "  . Performing the SSL/TLS handshake..." );
+    fflush( stdout );
+
+    while( ( ret = ssl_handshake( ssl ) ) != 0 )
+    {
+        if( ret != POLARSSL_ERR_NET_WANT_READ && ret != POLARSSL_ERR_NET_WANT_WRITE )
+        {
+            error_strerror( ret, (char *) buf, 1024 );
+            printf( " failed\n  ! ssl_handshake returned %d: %s\n\n", ret, buf );
+            return( -1 );
+        }
+    }
+
+    printf( " ok\n    [ Ciphersuite is %s ]\n",
+            ssl_get_ciphersuite( ssl ) );
+
+    /*
+     * 5. Verify the server certificate
+     */
+    printf( "  . Verifying peer X.509 certificate..." );
+
+    if( ( ret = ssl_get_verify_result( ssl ) ) != 0 )
+    {
+        printf( " failed\n" );
+
+        if( ( ret & BADCERT_EXPIRED ) != 0 )
+            printf( "  ! server certificate has expired\n" );
+
+        if( ( ret & BADCERT_REVOKED ) != 0 )
+            printf( "  ! server certificate has been revoked\n" );
+
+        if( ( ret & BADCERT_CN_MISMATCH ) != 0 )
+            printf( "  ! CN mismatch (expected CN=%s)\n", opt->server_name );
+
+        if( ( ret & BADCERT_NOT_TRUSTED ) != 0 )
+            printf( "  ! self-signed or not signed by a trusted CA\n" );
+
+        printf( "\n" );
+    }
+    else
+        printf( " ok\n" );
+
+    printf( "  . Peer certificate information    ...\n" );
+    x509parse_cert_info( (char *) buf, sizeof( buf ) - 1, "      ", ssl->peer_cert );
+    printf( "%s\n", buf );
+
+    return( 0 );
+}
+
+int write_ssl_data( ssl_context *ssl, unsigned char *buf, size_t len )
+{
+    int ret;
+
+    printf("\n%s", buf);
+    while( len && ( ret = ssl_write( ssl, buf, len ) ) <= 0 )
+    {
+        if( ret != POLARSSL_ERR_NET_WANT_READ && ret != POLARSSL_ERR_NET_WANT_WRITE )
+        {
+            printf( " failed\n  ! ssl_write returned %d\n\n", ret );
+            return -1;
+        }
+    }
+
+    return( 0 );
+}
+
+int write_ssl_and_get_response( ssl_context *ssl, unsigned char *buf, size_t len )
+{
+    int ret;
+    unsigned char data[128];
+    char code[4];
+    size_t i, idx = 0;
+
+    printf("\n%s", buf);
+    while( len && ( ret = ssl_write( ssl, buf, len ) ) <= 0 )
+    {
+        if( ret != POLARSSL_ERR_NET_WANT_READ && ret != POLARSSL_ERR_NET_WANT_WRITE )
+        {
+            printf( " failed\n  ! ssl_write returned %d\n\n", ret );
+            return -1;
+        }
+    }
+
+    do
+    {
+        len = sizeof( data ) - 1;
+        memset( data, 0, sizeof( data ) );
+        ret = ssl_read( ssl, data, len );
+
+        if( ret == POLARSSL_ERR_NET_WANT_READ || ret == POLARSSL_ERR_NET_WANT_WRITE )
+            continue;
+
+        if( ret == POLARSSL_ERR_SSL_PEER_CLOSE_NOTIFY )
+            return -1;
+
+        if( ret <= 0 )
+        {
+            printf( "failed\n  ! ssl_read returned %d\n\n", ret );
+            return -1;
+        }
+
+        printf("\n%s", data);
+        len = ret;
+        for( i = 0; i < len; i++ )
+        {
+            if( data[i] != '\n' )
+            {
+                if( idx < 4 )
+                    code[ idx++ ] = data[i];
+                continue;
+            }
+
+            if( idx == 4 && code[0] >= '0' && code[0] <= '9' && code[3] == ' ' )
+            {
+                code[3] = '\0';
+                return atoi( code );
+            }
+            
+            idx = 0;
+        }
+    }
+    while( 1 );
+}
+
+int write_and_get_response( int sock_fd, unsigned char *buf, size_t len )
+{
+    int ret;
+    unsigned char data[128];
+    char code[4];
+    size_t i, idx = 0;
+
+    printf("\n%s", buf);
+    if( len && ( ret = write( sock_fd, buf, len ) ) <= 0 )
+    {
+        printf( " failed\n  ! ssl_write returned %d\n\n", ret );
+            return -1;
+    }
+
+    do
+    {
+        len = sizeof( data ) - 1;
+        memset( data, 0, sizeof( data ) );
+        ret = read( sock_fd, data, len );
+
+        if( ret <= 0 )
+        {
+            printf( "failed\n  ! read returned %d\n\n", ret );
+            return -1;
+        }
+
+        printf("\n%s", data);
+        len = ret;
+        for( i = 0; i < len; i++ )
+        {
+            if( data[i] != '\n' )
+            {
+                if( idx < 4 )
+                    code[ idx++ ] = data[i];
+                continue;
+            }
+
+            if( idx == 4 && code[0] >= '0' && code[0] <= '9' && code[3] == ' ' )
+            {
+                code[3] = '\0';
+                return atoi( code );
+            }
+            
+            idx = 0;
+        }
+    }
+    while( 1 );
+}
+
+#define USAGE \
+    "\n usage: ssl_mail_client param=<>...\n"               \
+    "\n acceptable parameters:\n"                           \
+    "    server_name=%%s      default: localhost\n"         \
+    "    server_port=%%d      default: 4433\n"              \
+    "    debug_level=%%d      default: 0 (disabled)\n"      \
+    "    authentication=%%d   default: 0 (disabled)\n"      \
+    "    mode=%%d             default: 0 (SSL/TLS) (1 for STARTTLS)\n"  \
+    "    user_name=%%s        default: \"user\"\n"          \
+    "    user_pwd=%%s         default: \"password\"\n"      \
+    "    mail_from=%%s        default: \"\"\n"              \
+    "    mail_to=%%s          default: \"\"\n"              \
+    "    crt_file=%%s         default: \"\" (pre-loaded)\n" \
+    "    key_file=%%s         default: \"\" (pre-loaded)\n" \
+    "    force_ciphersuite=<name>    default: all enabled\n"\
+    " acceptable ciphersuite names:\n"
+
+int main( int argc, char *argv[] )
+{
+    int ret = 0, len, server_fd;
+    unsigned char buf[1024];
+    unsigned char base[1024];
+    char hostname[32];
+    havege_state hs;
+    ssl_context ssl;
+    ssl_session ssn;
+    x509_cert cacert;
+    x509_cert clicert;
+    rsa_context rsa;
+    int i;
+    size_t j, n;
+    char *p, *q;
+    const int *list;
+
+    /*
+     * Make sure memory references are valid.
+     */
+    server_fd = 0;
+    memset( &ssn, 0, sizeof( ssl_session ) );
+    memset( &ssl, 0, sizeof( ssl_context ) );
+    memset( &cacert, 0, sizeof( x509_cert ) );
+    memset( &clicert, 0, sizeof( x509_cert ) );
+    memset( &rsa, 0, sizeof( rsa_context ) );
+
+    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.crt_file            = DFL_CRT_FILE;
+    opt.key_file            = DFL_KEY_FILE;
+    opt.force_ciphersuite[0]= DFL_FORCE_CIPHER;
+
+    for( i = 1; i < argc; i++ )
+    {
+        n = strlen( argv[i] );
+
+        for( j = 0; j < n; j++ )
+        {
+            if( argv[i][j] == '=')
+                break;
+
+            if( argv[i][j] >= 'A' && argv[i][j] <= 'Z' )
+                argv[i][j] |= 0x20;
+        }
+
+        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, "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
+     */
+    havege_init( &hs );
+
+    /*
+     * 1.1. Load the trusted CA
+     */
+    printf( "\n  . Loading the CA root certificate ..." );
+    fflush( stdout );
+
+    /*
+     * Alternatively, you may load the CA certificates from a .pem or
+     * .crt file by calling x509parse_crtfile( &cacert, "myca.crt" ).
+     */
+    ret = x509parse_crt( &cacert, (unsigned char *) test_ca_crt,
+                         strlen( test_ca_crt ) );
+    if( ret != 0 )
+    {
+        printf( " failed\n  !  x509parse_crt returned %d\n\n", ret );
+        goto exit;
+    }
+
+    printf( " ok\n" );
+
+    /*
+     * 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( strlen( opt.crt_file ) )
+        ret = x509parse_crtfile( &clicert, opt.crt_file );
+    else 
+        ret = x509parse_crt( &clicert, (unsigned char *) test_cli_crt,
+                strlen( test_cli_crt ) );
+    if( ret != 0 )
+    {
+        printf( " failed\n  !  x509parse_crt returned %d\n\n", ret );
+        goto exit;
+    }
+
+    if( strlen( opt.key_file ) )
+        ret = x509parse_keyfile( &rsa, opt.key_file, "" );
+    else
+        ret = x509parse_key( &rsa, (unsigned char *) test_cli_key,
+                strlen( test_cli_key ), NULL, 0 );
+
+    if( ret != 0 )
+    {
+        printf( " failed\n  !  x509parse_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 );
+
+    havege_init( &hs );
+
+    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, havege_rand, &hs );
+    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, ssl_default_ciphersuites );
+    else
+        ssl_set_ciphersuites( &ssl, opt.force_ciphersuite );
+
+    ssl_set_session( &ssl, 1, 600, &ssn );
+
+    ssl_set_ca_chain( &ssl, &cacert, NULL, opt.server_name );
+    ssl_set_own_cert( &ssl, &clicert, &rsa );
+
+    ssl_set_hostname( &ssl, opt.server_name );
+
+    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\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\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\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( opt.authentication )
+    {
+        printf( "  > Write AUTH LOGIN to server:" );
+        fflush( stdout );
+
+        len = sprintf( (char *) buf, "AUTH LOGIN\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, opt.user_name, strlen( opt.user_name ) );
+        len = sprintf( (char *) buf, "%s\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, opt.user_pwd, strlen( opt.user_pwd ) );
+        len = sprintf( (char *) buf, "%s\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" );
+    }
+
+    printf( "  > Write MAIL FROM to server:" );
+    fflush( stdout );
+
+    len = sprintf( (char *) buf, "MAIL FROM:<%s>\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>\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\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\nSubject: PolarSSL Test mail\n\n"
+            "This is a simple test mail from the "
+            "PolarSSL mail client example.\n"
+            "\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_free( &clicert );
+    x509_free( &cacert );
+    rsa_free( &rsa );
+    ssl_free( &ssl );
+
+    memset( &ssl, 0, sizeof( ssl ) );
+
+#ifdef WIN32
+    printf( "  + Press Enter to exit this program.\n" );
+    fflush( stdout ); getchar();
+#endif
+
+    return( ret );
+}