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1 /*
2  *  SSL client for SMTP servers
3  *
4  *  Copyright The Mbed TLS Contributors
5  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6  *
7  *  This file is provided under the Apache License 2.0, or the
8  *  GNU General Public License v2.0 or later.
9  *
10  *  **********
11  *  Apache License 2.0:
12  *
13  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
14  *  not use this file except in compliance with the License.
15  *  You may obtain a copy of the License at
16  *
17  *  http://www.apache.org/licenses/LICENSE-2.0
18  *
19  *  Unless required by applicable law or agreed to in writing, software
20  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
21  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
22  *  See the License for the specific language governing permissions and
23  *  limitations under the License.
24  *
25  *  **********
26  *
27  *  **********
28  *  GNU General Public License v2.0 or later:
29  *
30  *  This program is free software; you can redistribute it and/or modify
31  *  it under the terms of the GNU General Public License as published by
32  *  the Free Software Foundation; either version 2 of the License, or
33  *  (at your option) any later version.
34  *
35  *  This program is distributed in the hope that it will be useful,
36  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
37  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
38  *  GNU General Public License for more details.
39  *
40  *  You should have received a copy of the GNU General Public License along
41  *  with this program; if not, write to the Free Software Foundation, Inc.,
42  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
43  *
44  *  **********
45  */
46 
47 /* Enable definition of gethostname() even when compiling with -std=c99. Must
48  * be set before config.h, which pulls in glibc's features.h indirectly.
49  * Harmless on other platforms. */
50 #define _POSIX_C_SOURCE 200112L
51 
52 #if defined(__NetBSD__)
53 #define _XOPEN_SOURCE 600
54 #endif
55 
56 #if !defined(MBEDTLS_CONFIG_FILE)
57 #include "mbedtls/config.h"
58 #else
59 #include MBEDTLS_CONFIG_FILE
60 #endif
61 
62 #if defined(MBEDTLS_PLATFORM_C)
63 #include "mbedtls/platform.h"
64 #else
65 #include <stdio.h>
66 #include <stdlib.h>
67 #define mbedtls_time            time
68 #define mbedtls_time_t          time_t
69 #define mbedtls_fprintf         fprintf
70 #define mbedtls_printf          printf
71 #define mbedtls_exit            exit
72 #define MBEDTLS_EXIT_SUCCESS    EXIT_SUCCESS
73 #define MBEDTLS_EXIT_FAILURE    EXIT_FAILURE
74 #endif /* MBEDTLS_PLATFORM_C */
75 
76 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_ENTROPY_C) ||  \
77     !defined(MBEDTLS_SSL_TLS_C) || !defined(MBEDTLS_SSL_CLI_C) || \
78     !defined(MBEDTLS_NET_C) || !defined(MBEDTLS_RSA_C) ||         \
79     !defined(MBEDTLS_CTR_DRBG_C) || !defined(MBEDTLS_X509_CRT_PARSE_C) || \
80     !defined(MBEDTLS_FS_IO)
main(void)81 int main( void )
82 {
83     mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_ENTROPY_C and/or "
84            "MBEDTLS_SSL_TLS_C and/or MBEDTLS_SSL_CLI_C and/or "
85            "MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "
86            "MBEDTLS_CTR_DRBG_C and/or MBEDTLS_X509_CRT_PARSE_C "
87            "not defined.\n");
88     mbedtls_exit( 0 );
89 }
90 #else
91 
92 #include "mbedtls/base64.h"
93 #include "mbedtls/error.h"
94 #include "mbedtls/net_sockets.h"
95 #include "mbedtls/ssl.h"
96 #include "mbedtls/entropy.h"
97 #include "mbedtls/ctr_drbg.h"
98 #include "mbedtls/certs.h"
99 #include "mbedtls/x509.h"
100 
101 #include <stdlib.h>
102 #include <string.h>
103 
104 #if !defined(_MSC_VER) || defined(EFIX64) || defined(EFI32)
105 #include <unistd.h>
106 #else
107 #include <io.h>
108 #endif
109 
110 #if defined(_WIN32) || defined(_WIN32_WCE)
111 #include <winsock2.h>
112 #include <windows.h>
113 
114 #if defined(_MSC_VER)
115 #if defined(_WIN32_WCE)
116 #pragma comment( lib, "ws2.lib" )
117 #else
118 #pragma comment( lib, "ws2_32.lib" )
119 #endif
120 #endif /* _MSC_VER */
121 #endif
122 
123 #define DFL_SERVER_NAME         "localhost"
124 #define DFL_SERVER_PORT         "465"
125 #define DFL_USER_NAME           "user"
126 #define DFL_USER_PWD            "password"
127 #define DFL_MAIL_FROM           ""
128 #define DFL_MAIL_TO             ""
129 #define DFL_DEBUG_LEVEL         0
130 #define DFL_CA_FILE             ""
131 #define DFL_CRT_FILE            ""
132 #define DFL_KEY_FILE            ""
133 #define DFL_FORCE_CIPHER        0
134 #define DFL_MODE                0
135 #define DFL_AUTHENTICATION      0
136 
137 #define MODE_SSL_TLS            0
138 #define MODE_STARTTLS           0
139 
140 #if defined(MBEDTLS_BASE64_C)
141 #define USAGE_AUTH \
142     "    authentication=%%d   default: 0 (disabled)\n"          \
143     "    user_name=%%s        default: \"" DFL_USER_NAME "\"\n" \
144     "    user_pwd=%%s         default: \"" DFL_USER_PWD "\"\n"
145 #else
146 #define USAGE_AUTH \
147     "    authentication options disabled. (Require MBEDTLS_BASE64_C)\n"
148 #endif /* MBEDTLS_BASE64_C */
149 
150 #if defined(MBEDTLS_FS_IO)
151 #define USAGE_IO \
152     "    ca_file=%%s          default: \"\" (pre-loaded)\n" \
153     "    crt_file=%%s         default: \"\" (pre-loaded)\n" \
154     "    key_file=%%s         default: \"\" (pre-loaded)\n"
155 #else
156 #define USAGE_IO \
157     "    No file operations available (MBEDTLS_FS_IO not defined)\n"
158 #endif /* MBEDTLS_FS_IO */
159 
160 #define USAGE \
161     "\n usage: ssl_mail_client param=<>...\n"                 \
162     "\n acceptable parameters:\n"                             \
163     "    server_name=%%s      default: " DFL_SERVER_NAME "\n" \
164     "    server_port=%%d      default: " DFL_SERVER_PORT "\n" \
165     "    debug_level=%%d      default: 0 (disabled)\n"        \
166     "    mode=%%d             default: 0 (SSL/TLS) (1 for STARTTLS)\n"  \
167     USAGE_AUTH                                                \
168     "    mail_from=%%s        default: \"\"\n"                \
169     "    mail_to=%%s          default: \"\"\n"                \
170     USAGE_IO                                                  \
171     "    force_ciphersuite=<name>    default: all enabled\n"  \
172     " acceptable ciphersuite names:\n"
173 
174 
175 /*
176  * global options
177  */
178 struct options
179 {
180     const char *server_name;    /* hostname of the server (client only)     */
181     const char *server_port;    /* port on which the ssl service runs       */
182     int debug_level;            /* level of debugging                       */
183     int authentication;         /* if authentication is required            */
184     int mode;                   /* SSL/TLS (0) or STARTTLS (1)              */
185     const char *user_name;      /* username to use for authentication       */
186     const char *user_pwd;       /* password to use for authentication       */
187     const char *mail_from;      /* E-Mail address to use as sender          */
188     const char *mail_to;        /* E-Mail address to use as recipient       */
189     const char *ca_file;        /* the file with the CA certificate(s)      */
190     const char *crt_file;       /* the file with the client certificate     */
191     const char *key_file;       /* the file with the client key             */
192     int force_ciphersuite[2];   /* protocol/ciphersuite to use, or all      */
193 } opt;
194 
my_debug(void * ctx,int level,const char * file,int line,const char * str)195 static void my_debug( void *ctx, int level,
196                       const char *file, int line,
197                       const char *str )
198 {
199     ((void) level);
200 
201     mbedtls_fprintf( (FILE *) ctx, "%s:%04d: %s", file, line, str );
202     fflush(  (FILE *) ctx  );
203 }
204 
do_handshake(mbedtls_ssl_context * ssl)205 static int do_handshake( mbedtls_ssl_context *ssl )
206 {
207     int ret;
208     uint32_t flags;
209     unsigned char buf[1024];
210     memset(buf, 0, 1024);
211 
212     /*
213      * 4. Handshake
214      */
215     mbedtls_printf( "  . Performing the SSL/TLS handshake..." );
216     fflush( stdout );
217 
218     while( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
219     {
220         if( ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE )
221         {
222 #if defined(MBEDTLS_ERROR_C)
223             mbedtls_strerror( ret, (char *) buf, 1024 );
224 #endif
225             mbedtls_printf( " failed\n  ! mbedtls_ssl_handshake returned %d: %s\n\n", ret, buf );
226             return( -1 );
227         }
228     }
229 
230     mbedtls_printf( " ok\n    [ Ciphersuite is %s ]\n",
231             mbedtls_ssl_get_ciphersuite( ssl ) );
232 
233     /*
234      * 5. Verify the server certificate
235      */
236     mbedtls_printf( "  . Verifying peer X.509 certificate..." );
237 
238     /* In real life, we probably want to bail out when ret != 0 */
239     if( ( flags = mbedtls_ssl_get_verify_result( ssl ) ) != 0 )
240     {
241         char vrfy_buf[512];
242 
243         mbedtls_printf( " failed\n" );
244 
245         mbedtls_x509_crt_verify_info( vrfy_buf, sizeof( vrfy_buf ), "  ! ", flags );
246 
247         mbedtls_printf( "%s\n", vrfy_buf );
248     }
249     else
250         mbedtls_printf( " ok\n" );
251 
252     mbedtls_printf( "  . Peer certificate information    ...\n" );
253     mbedtls_x509_crt_info( (char *) buf, sizeof( buf ) - 1, "      ",
254                    mbedtls_ssl_get_peer_cert( ssl ) );
255     mbedtls_printf( "%s\n", buf );
256 
257     return( 0 );
258 }
259 
write_ssl_data(mbedtls_ssl_context * ssl,unsigned char * buf,size_t len)260 static int write_ssl_data( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
261 {
262     int ret;
263 
264     mbedtls_printf("\n%s", buf);
265     while( len && ( ret = mbedtls_ssl_write( ssl, buf, len ) ) <= 0 )
266     {
267         if( ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE )
268         {
269             mbedtls_printf( " failed\n  ! mbedtls_ssl_write returned %d\n\n", ret );
270             return -1;
271         }
272     }
273 
274     return( 0 );
275 }
276 
write_ssl_and_get_response(mbedtls_ssl_context * ssl,unsigned char * buf,size_t len)277 static int write_ssl_and_get_response( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
278 {
279     int ret;
280     unsigned char data[128];
281     char code[4];
282     size_t i, idx = 0;
283 
284     mbedtls_printf("\n%s", buf);
285     while( len && ( ret = mbedtls_ssl_write( ssl, buf, len ) ) <= 0 )
286     {
287         if( ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE )
288         {
289             mbedtls_printf( " failed\n  ! mbedtls_ssl_write returned %d\n\n", ret );
290             return -1;
291         }
292     }
293 
294     do
295     {
296         len = sizeof( data ) - 1;
297         memset( data, 0, sizeof( data ) );
298         ret = mbedtls_ssl_read( ssl, data, len );
299 
300         if( ret == MBEDTLS_ERR_SSL_WANT_READ || ret == MBEDTLS_ERR_SSL_WANT_WRITE )
301             continue;
302 
303         if( ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY )
304             return -1;
305 
306         if( ret <= 0 )
307         {
308             mbedtls_printf( "failed\n  ! mbedtls_ssl_read returned %d\n\n", ret );
309             return -1;
310         }
311 
312         mbedtls_printf("\n%s", data);
313         len = ret;
314         for( i = 0; i < len; i++ )
315         {
316             if( data[i] != '\n' )
317             {
318                 if( idx < 4 )
319                     code[ idx++ ] = data[i];
320                 continue;
321             }
322 
323             if( idx == 4 && code[0] >= '0' && code[0] <= '9' && code[3] == ' ' )
324             {
325                 code[3] = '\0';
326                 return atoi( code );
327             }
328 
329             idx = 0;
330         }
331     }
332     while( 1 );
333 }
334 
write_and_get_response(mbedtls_net_context * sock_fd,unsigned char * buf,size_t len)335 static int write_and_get_response( mbedtls_net_context *sock_fd, unsigned char *buf, size_t len )
336 {
337     int ret;
338     unsigned char data[128];
339     char code[4];
340     size_t i, idx = 0;
341 
342     mbedtls_printf("\n%s", buf);
343     if( len && ( ret = mbedtls_net_send( sock_fd, buf, len ) ) <= 0 )
344     {
345         mbedtls_printf( " failed\n  ! mbedtls_net_send returned %d\n\n", ret );
346             return -1;
347     }
348 
349     do
350     {
351         len = sizeof( data ) - 1;
352         memset( data, 0, sizeof( data ) );
353         ret = mbedtls_net_recv( sock_fd, data, len );
354 
355         if( ret <= 0 )
356         {
357             mbedtls_printf( "failed\n  ! mbedtls_net_recv returned %d\n\n", ret );
358             return -1;
359         }
360 
361         data[len] = '\0';
362         mbedtls_printf("\n%s", data);
363         len = ret;
364         for( i = 0; i < len; i++ )
365         {
366             if( data[i] != '\n' )
367             {
368                 if( idx < 4 )
369                     code[ idx++ ] = data[i];
370                 continue;
371             }
372 
373             if( idx == 4 && code[0] >= '0' && code[0] <= '9' && code[3] == ' ' )
374             {
375                 code[3] = '\0';
376                 return atoi( code );
377             }
378 
379             idx = 0;
380         }
381     }
382     while( 1 );
383 }
384 
main(int argc,char * argv[])385 int main( int argc, char *argv[] )
386 {
387     int ret = 1, len;
388     int exit_code = MBEDTLS_EXIT_FAILURE;
389     mbedtls_net_context server_fd;
390 #if defined(MBEDTLS_BASE64_C)
391     unsigned char base[1024];
392     /* buf is used as the destination buffer for printing base with the format:
393      * "%s\r\n". Hence, the size of buf should be at least the size of base
394      * plus 2 bytes for the \r and \n characters.
395      */
396     unsigned char buf[sizeof( base ) + 2];
397 #else
398     unsigned char buf[1024];
399 #endif
400     char hostname[32];
401     const char *pers = "ssl_mail_client";
402 
403     mbedtls_entropy_context entropy;
404     mbedtls_ctr_drbg_context ctr_drbg;
405     mbedtls_ssl_context ssl;
406     mbedtls_ssl_config conf;
407     mbedtls_x509_crt cacert;
408     mbedtls_x509_crt clicert;
409     mbedtls_pk_context pkey;
410     int i;
411     size_t n;
412     char *p, *q;
413     const int *list;
414 
415     /*
416      * Make sure memory references are valid in case we exit early.
417      */
418     mbedtls_net_init( &server_fd );
419     mbedtls_ssl_init( &ssl );
420     mbedtls_ssl_config_init( &conf );
421     memset( &buf, 0, sizeof( buf ) );
422     mbedtls_x509_crt_init( &cacert );
423     mbedtls_x509_crt_init( &clicert );
424     mbedtls_pk_init( &pkey );
425     mbedtls_ctr_drbg_init( &ctr_drbg );
426 
427     if( argc == 0 )
428     {
429     usage:
430         mbedtls_printf( USAGE );
431 
432         list = mbedtls_ssl_list_ciphersuites();
433         while( *list )
434         {
435             mbedtls_printf("    %s\n", mbedtls_ssl_get_ciphersuite_name( *list ) );
436             list++;
437         }
438         mbedtls_printf("\n");
439         goto exit;
440     }
441 
442     opt.server_name         = DFL_SERVER_NAME;
443     opt.server_port         = DFL_SERVER_PORT;
444     opt.debug_level         = DFL_DEBUG_LEVEL;
445     opt.authentication      = DFL_AUTHENTICATION;
446     opt.mode                = DFL_MODE;
447     opt.user_name           = DFL_USER_NAME;
448     opt.user_pwd            = DFL_USER_PWD;
449     opt.mail_from           = DFL_MAIL_FROM;
450     opt.mail_to             = DFL_MAIL_TO;
451     opt.ca_file             = DFL_CA_FILE;
452     opt.crt_file            = DFL_CRT_FILE;
453     opt.key_file            = DFL_KEY_FILE;
454     opt.force_ciphersuite[0]= DFL_FORCE_CIPHER;
455 
456     for( i = 1; i < argc; i++ )
457     {
458         p = argv[i];
459         if( ( q = strchr( p, '=' ) ) == NULL )
460             goto usage;
461         *q++ = '\0';
462 
463         if( strcmp( p, "server_name" ) == 0 )
464             opt.server_name = q;
465         else if( strcmp( p, "server_port" ) == 0 )
466             opt.server_port = q;
467         else if( strcmp( p, "debug_level" ) == 0 )
468         {
469             opt.debug_level = atoi( q );
470             if( opt.debug_level < 0 || opt.debug_level > 65535 )
471                 goto usage;
472         }
473         else if( strcmp( p, "authentication" ) == 0 )
474         {
475             opt.authentication = atoi( q );
476             if( opt.authentication < 0 || opt.authentication > 1 )
477                 goto usage;
478         }
479         else if( strcmp( p, "mode" ) == 0 )
480         {
481             opt.mode = atoi( q );
482             if( opt.mode < 0 || opt.mode > 1 )
483                 goto usage;
484         }
485         else if( strcmp( p, "user_name" ) == 0 )
486             opt.user_name = q;
487         else if( strcmp( p, "user_pwd" ) == 0 )
488             opt.user_pwd = q;
489         else if( strcmp( p, "mail_from" ) == 0 )
490             opt.mail_from = q;
491         else if( strcmp( p, "mail_to" ) == 0 )
492             opt.mail_to = q;
493         else if( strcmp( p, "ca_file" ) == 0 )
494             opt.ca_file = q;
495         else if( strcmp( p, "crt_file" ) == 0 )
496             opt.crt_file = q;
497         else if( strcmp( p, "key_file" ) == 0 )
498             opt.key_file = q;
499         else if( strcmp( p, "force_ciphersuite" ) == 0 )
500         {
501             opt.force_ciphersuite[0] = -1;
502 
503             opt.force_ciphersuite[0] = mbedtls_ssl_get_ciphersuite_id( q );
504 
505             if( opt.force_ciphersuite[0] <= 0 )
506                 goto usage;
507 
508             opt.force_ciphersuite[1] = 0;
509         }
510         else
511             goto usage;
512     }
513 
514     /*
515      * 0. Initialize the RNG and the session data
516      */
517     mbedtls_printf( "\n  . Seeding the random number generator..." );
518     fflush( stdout );
519 
520     mbedtls_entropy_init( &entropy );
521     if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
522                                (const unsigned char *) pers,
523                                strlen( pers ) ) ) != 0 )
524     {
525         mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret );
526         goto exit;
527     }
528 
529     mbedtls_printf( " ok\n" );
530 
531     /*
532      * 1.1. Load the trusted CA
533      */
534     mbedtls_printf( "  . Loading the CA root certificate ..." );
535     fflush( stdout );
536 
537 #if defined(MBEDTLS_FS_IO)
538     if( strlen( opt.ca_file ) )
539         ret = mbedtls_x509_crt_parse_file( &cacert, opt.ca_file );
540     else
541 #endif
542 #if defined(MBEDTLS_CERTS_C) && defined(MBEDTLS_PEM_PARSE_C)
543         ret = mbedtls_x509_crt_parse( &cacert, (const unsigned char *) mbedtls_test_cas_pem,
544                               mbedtls_test_cas_pem_len );
545 #else
546     {
547         mbedtls_printf("MBEDTLS_CERTS_C and/or MBEDTLS_PEM_PARSE_C not defined.");
548         goto exit;
549     }
550 #endif
551     if( ret < 0 )
552     {
553         mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret );
554         goto exit;
555     }
556 
557     mbedtls_printf( " ok (%d skipped)\n", ret );
558 
559     /*
560      * 1.2. Load own certificate and private key
561      *
562      * (can be skipped if client authentication is not required)
563      */
564     mbedtls_printf( "  . Loading the client cert. and key..." );
565     fflush( stdout );
566 
567 #if defined(MBEDTLS_FS_IO)
568     if( strlen( opt.crt_file ) )
569         ret = mbedtls_x509_crt_parse_file( &clicert, opt.crt_file );
570     else
571 #endif
572 #if defined(MBEDTLS_CERTS_C)
573         ret = mbedtls_x509_crt_parse( &clicert, (const unsigned char *) mbedtls_test_cli_crt,
574                               mbedtls_test_cli_crt_len );
575 #else
576     {
577         mbedtls_printf("MBEDTLS_CERTS_C not defined.");
578         goto exit;
579     }
580 #endif
581     if( ret != 0 )
582     {
583         mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret );
584         goto exit;
585     }
586 
587 #if defined(MBEDTLS_FS_IO)
588     if( strlen( opt.key_file ) )
589         ret = mbedtls_pk_parse_keyfile( &pkey, opt.key_file, "" );
590     else
591 #endif
592 #if defined(MBEDTLS_CERTS_C) && defined(MBEDTLS_PEM_PARSE_C)
593         ret = mbedtls_pk_parse_key( &pkey, (const unsigned char *) mbedtls_test_cli_key,
594                 mbedtls_test_cli_key_len, NULL, 0 );
595 #else
596     {
597         mbedtls_printf("MBEDTLS_CERTS_C or MBEDTLS_PEM_PARSE_C not defined.");
598         goto exit;
599     }
600 #endif
601     if( ret != 0 )
602     {
603         mbedtls_printf( " failed\n  !  mbedtls_pk_parse_key returned %d\n\n", ret );
604         goto exit;
605     }
606 
607     mbedtls_printf( " ok\n" );
608 
609     /*
610      * 2. Start the connection
611      */
612     mbedtls_printf( "  . Connecting to tcp/%s/%s...", opt.server_name,
613                                                 opt.server_port );
614     fflush( stdout );
615 
616     if( ( ret = mbedtls_net_connect( &server_fd, opt.server_name,
617                              opt.server_port, MBEDTLS_NET_PROTO_TCP ) ) != 0 )
618     {
619         mbedtls_printf( " failed\n  ! mbedtls_net_connect returned %d\n\n", ret );
620         goto exit;
621     }
622 
623     mbedtls_printf( " ok\n" );
624 
625     /*
626      * 3. Setup stuff
627      */
628     mbedtls_printf( "  . Setting up the SSL/TLS structure..." );
629     fflush( stdout );
630 
631     if( ( ret = mbedtls_ssl_config_defaults( &conf,
632                     MBEDTLS_SSL_IS_CLIENT,
633                     MBEDTLS_SSL_TRANSPORT_STREAM,
634                     MBEDTLS_SSL_PRESET_DEFAULT ) ) != 0 )
635     {
636         mbedtls_printf( " failed\n  ! mbedtls_ssl_config_defaults returned %d\n\n", ret );
637         goto exit;
638     }
639 
640     /* OPTIONAL is not optimal for security,
641      * but makes interop easier in this simplified example */
642     mbedtls_ssl_conf_authmode( &conf, MBEDTLS_SSL_VERIFY_OPTIONAL );
643 
644     mbedtls_ssl_conf_rng( &conf, mbedtls_ctr_drbg_random, &ctr_drbg );
645     mbedtls_ssl_conf_dbg( &conf, my_debug, stdout );
646 
647     if( opt.force_ciphersuite[0] != DFL_FORCE_CIPHER )
648         mbedtls_ssl_conf_ciphersuites( &conf, opt.force_ciphersuite );
649 
650     mbedtls_ssl_conf_ca_chain( &conf, &cacert, NULL );
651     if( ( ret = mbedtls_ssl_conf_own_cert( &conf, &clicert, &pkey ) ) != 0 )
652     {
653         mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_own_cert returned %d\n\n", ret );
654         goto exit;
655     }
656 
657     if( ( ret = mbedtls_ssl_setup( &ssl, &conf ) ) != 0 )
658     {
659         mbedtls_printf( " failed\n  ! mbedtls_ssl_setup returned %d\n\n", ret );
660         goto exit;
661     }
662 
663     if( ( ret = mbedtls_ssl_set_hostname( &ssl, opt.server_name ) ) != 0 )
664     {
665         mbedtls_printf( " failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n", ret );
666         goto exit;
667     }
668 
669     mbedtls_ssl_set_bio( &ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv, NULL );
670 
671     mbedtls_printf( " ok\n" );
672 
673     if( opt.mode == MODE_SSL_TLS )
674     {
675         if( do_handshake( &ssl ) != 0 )
676             goto exit;
677 
678         mbedtls_printf( "  > Get header from server:" );
679         fflush( stdout );
680 
681         ret = write_ssl_and_get_response( &ssl, buf, 0 );
682         if( ret < 200 || ret > 299 )
683         {
684             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
685             goto exit;
686         }
687 
688         mbedtls_printf(" ok\n" );
689 
690         mbedtls_printf( "  > Write EHLO to server:" );
691         fflush( stdout );
692 
693         gethostname( hostname, 32 );
694         len = sprintf( (char *) buf, "EHLO %s\r\n", hostname );
695         ret = write_ssl_and_get_response( &ssl, buf, len );
696         if( ret < 200 || ret > 299 )
697         {
698             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
699             goto exit;
700         }
701     }
702     else
703     {
704         mbedtls_printf( "  > Get header from server:" );
705         fflush( stdout );
706 
707         ret = write_and_get_response( &server_fd, buf, 0 );
708         if( ret < 200 || ret > 299 )
709         {
710             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
711             goto exit;
712         }
713 
714         mbedtls_printf(" ok\n" );
715 
716         mbedtls_printf( "  > Write EHLO to server:" );
717         fflush( stdout );
718 
719         gethostname( hostname, 32 );
720         len = sprintf( (char *) buf, "EHLO %s\r\n", hostname );
721         ret = write_and_get_response( &server_fd, buf, len );
722         if( ret < 200 || ret > 299 )
723         {
724             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
725             goto exit;
726         }
727 
728         mbedtls_printf(" ok\n" );
729 
730         mbedtls_printf( "  > Write STARTTLS to server:" );
731         fflush( stdout );
732 
733         gethostname( hostname, 32 );
734         len = sprintf( (char *) buf, "STARTTLS\r\n" );
735         ret = write_and_get_response( &server_fd, buf, len );
736         if( ret < 200 || ret > 299 )
737         {
738             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
739             goto exit;
740         }
741 
742         mbedtls_printf(" ok\n" );
743 
744         if( do_handshake( &ssl ) != 0 )
745             goto exit;
746     }
747 
748 #if defined(MBEDTLS_BASE64_C)
749     if( opt.authentication )
750     {
751         mbedtls_printf( "  > Write AUTH LOGIN to server:" );
752         fflush( stdout );
753 
754         len = sprintf( (char *) buf, "AUTH LOGIN\r\n" );
755         ret = write_ssl_and_get_response( &ssl, buf, len );
756         if( ret < 200 || ret > 399 )
757         {
758             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
759             goto exit;
760         }
761 
762         mbedtls_printf(" ok\n" );
763 
764         mbedtls_printf( "  > Write username to server: %s", opt.user_name );
765         fflush( stdout );
766 
767         ret = mbedtls_base64_encode( base, sizeof( base ), &n, (const unsigned char *) opt.user_name,
768                              strlen( opt.user_name ) );
769 
770         if( ret != 0 ) {
771             mbedtls_printf( " failed\n  ! mbedtls_base64_encode returned %d\n\n", ret );
772             goto exit;
773         }
774         len = sprintf( (char *) buf, "%s\r\n", base );
775         ret = write_ssl_and_get_response( &ssl, buf, len );
776         if( ret < 300 || ret > 399 )
777         {
778             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
779             goto exit;
780         }
781 
782         mbedtls_printf(" ok\n" );
783 
784         mbedtls_printf( "  > Write password to server: %s", opt.user_pwd );
785         fflush( stdout );
786 
787         ret = mbedtls_base64_encode( base, sizeof( base ), &n, (const unsigned char *) opt.user_pwd,
788                              strlen( opt.user_pwd ) );
789 
790         if( ret != 0 ) {
791             mbedtls_printf( " failed\n  ! mbedtls_base64_encode returned %d\n\n", ret );
792             goto exit;
793         }
794         len = sprintf( (char *) buf, "%s\r\n", base );
795         ret = write_ssl_and_get_response( &ssl, buf, len );
796         if( ret < 200 || ret > 399 )
797         {
798             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
799             goto exit;
800         }
801 
802         mbedtls_printf(" ok\n" );
803     }
804 #endif
805 
806     mbedtls_printf( "  > Write MAIL FROM to server:" );
807     fflush( stdout );
808 
809     len = sprintf( (char *) buf, "MAIL FROM:<%s>\r\n", opt.mail_from );
810     ret = write_ssl_and_get_response( &ssl, buf, len );
811     if( ret < 200 || ret > 299 )
812     {
813         mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
814         goto exit;
815     }
816 
817     mbedtls_printf(" ok\n" );
818 
819     mbedtls_printf( "  > Write RCPT TO to server:" );
820     fflush( stdout );
821 
822     len = sprintf( (char *) buf, "RCPT TO:<%s>\r\n", opt.mail_to );
823     ret = write_ssl_and_get_response( &ssl, buf, len );
824     if( ret < 200 || ret > 299 )
825     {
826         mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
827         goto exit;
828     }
829 
830     mbedtls_printf(" ok\n" );
831 
832     mbedtls_printf( "  > Write DATA to server:" );
833     fflush( stdout );
834 
835     len = sprintf( (char *) buf, "DATA\r\n" );
836     ret = write_ssl_and_get_response( &ssl, buf, len );
837     if( ret < 300 || ret > 399 )
838     {
839         mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
840         goto exit;
841     }
842 
843     mbedtls_printf(" ok\n" );
844 
845     mbedtls_printf( "  > Write content to server:" );
846     fflush( stdout );
847 
848     len = sprintf( (char *) buf, "From: %s\r\nSubject: mbed TLS Test mail\r\n\r\n"
849             "This is a simple test mail from the "
850             "mbed TLS mail client example.\r\n"
851             "\r\n"
852             "Enjoy!", opt.mail_from );
853     ret = write_ssl_data( &ssl, buf, len );
854 
855     len = sprintf( (char *) buf, "\r\n.\r\n");
856     ret = write_ssl_and_get_response( &ssl, buf, len );
857     if( ret < 200 || ret > 299 )
858     {
859         mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
860         goto exit;
861     }
862 
863     mbedtls_printf(" ok\n" );
864 
865     mbedtls_ssl_close_notify( &ssl );
866 
867     exit_code = MBEDTLS_EXIT_SUCCESS;
868 
869 exit:
870 
871     mbedtls_net_free( &server_fd );
872     mbedtls_x509_crt_free( &clicert );
873     mbedtls_x509_crt_free( &cacert );
874     mbedtls_pk_free( &pkey );
875     mbedtls_ssl_free( &ssl );
876     mbedtls_ssl_config_free( &conf );
877     mbedtls_ctr_drbg_free( &ctr_drbg );
878     mbedtls_entropy_free( &entropy );
879 
880 #if defined(_WIN32)
881     mbedtls_printf( "  + Press Enter to exit this program.\n" );
882     fflush( stdout ); getchar();
883 #endif
884 
885     mbedtls_exit( exit_code );
886 }
887 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ENTROPY_C && MBEDTLS_SSL_TLS_C &&
888           MBEDTLS_SSL_CLI_C && MBEDTLS_NET_C && MBEDTLS_RSA_C **
889           MBEDTLS_CTR_DRBG_C */
890