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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
6  *
7  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
8  *  not use this file except in compliance with the License.
9  *  You may obtain a copy of the License at
10  *
11  *  http://www.apache.org/licenses/LICENSE-2.0
12  *
13  *  Unless required by applicable law or agreed to in writing, software
14  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16  *  See the License for the specific language governing permissions and
17  *  limitations under the License.
18  */
19 
20 /* Enable definition of gethostname() even when compiling with -std=c99. Must
21  * be set before mbedtls_config.h, which pulls in glibc's features.h indirectly.
22  * Harmless on other platforms. */
23 
24 #define _POSIX_C_SOURCE 200112L
25 #define _XOPEN_SOURCE 600
26 
27 #include "mbedtls/build_info.h"
28 
29 #include "mbedtls/platform.h"
30 
31 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_ENTROPY_C) ||  \
32     !defined(MBEDTLS_SSL_TLS_C) || !defined(MBEDTLS_SSL_CLI_C) || \
33     !defined(MBEDTLS_NET_C) || !defined(MBEDTLS_RSA_C) ||         \
34     !defined(MBEDTLS_CTR_DRBG_C) || !defined(MBEDTLS_X509_CRT_PARSE_C) || \
35     !defined(MBEDTLS_FS_IO)
main(void)36 int main( void )
37 {
38     mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_ENTROPY_C and/or "
39            "MBEDTLS_SSL_TLS_C and/or MBEDTLS_SSL_CLI_C and/or "
40            "MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "
41            "MBEDTLS_CTR_DRBG_C and/or MBEDTLS_X509_CRT_PARSE_C "
42            "not defined.\n");
43     mbedtls_exit( 0 );
44 }
45 #else
46 
47 #include "mbedtls/base64.h"
48 #include "mbedtls/error.h"
49 #include "mbedtls/net_sockets.h"
50 #include "mbedtls/ssl.h"
51 #include "mbedtls/entropy.h"
52 #include "mbedtls/ctr_drbg.h"
53 #include "test/certs.h"
54 #include "mbedtls/x509.h"
55 
56 #include <stdlib.h>
57 #include <string.h>
58 
59 #if !defined(_MSC_VER) || defined(EFIX64) || defined(EFI32)
60 #include <unistd.h>
61 #else
62 #include <io.h>
63 #endif
64 
65 #if defined(_WIN32) || defined(_WIN32_WCE)
66 #include <winsock2.h>
67 #include <windows.h>
68 
69 #if defined(_MSC_VER)
70 #if defined(_WIN32_WCE)
71 #pragma comment( lib, "ws2.lib" )
72 #else
73 #pragma comment( lib, "ws2_32.lib" )
74 #endif
75 #endif /* _MSC_VER */
76 #endif
77 
78 #define DFL_SERVER_NAME         "localhost"
79 #define DFL_SERVER_PORT         "465"
80 #define DFL_USER_NAME           "user"
81 #define DFL_USER_PWD            "password"
82 #define DFL_MAIL_FROM           ""
83 #define DFL_MAIL_TO             ""
84 #define DFL_DEBUG_LEVEL         0
85 #define DFL_CA_FILE             ""
86 #define DFL_CRT_FILE            ""
87 #define DFL_KEY_FILE            ""
88 #define DFL_FORCE_CIPHER        0
89 #define DFL_MODE                0
90 #define DFL_AUTHENTICATION      0
91 
92 #define MODE_SSL_TLS            0
93 #define MODE_STARTTLS           0
94 
95 #if defined(MBEDTLS_BASE64_C)
96 #define USAGE_AUTH \
97     "    authentication=%%d   default: 0 (disabled)\n"          \
98     "    user_name=%%s        default: \"" DFL_USER_NAME "\"\n" \
99     "    user_pwd=%%s         default: \"" DFL_USER_PWD "\"\n"
100 #else
101 #define USAGE_AUTH \
102     "    authentication options disabled. (Require MBEDTLS_BASE64_C)\n"
103 #endif /* MBEDTLS_BASE64_C */
104 
105 #if defined(MBEDTLS_FS_IO)
106 #define USAGE_IO \
107     "    ca_file=%%s          default: \"\" (pre-loaded)\n" \
108     "    crt_file=%%s         default: \"\" (pre-loaded)\n" \
109     "    key_file=%%s         default: \"\" (pre-loaded)\n"
110 #else
111 #define USAGE_IO \
112     "    No file operations available (MBEDTLS_FS_IO not defined)\n"
113 #endif /* MBEDTLS_FS_IO */
114 
115 #define USAGE \
116     "\n usage: ssl_mail_client param=<>...\n"                 \
117     "\n acceptable parameters:\n"                             \
118     "    server_name=%%s      default: " DFL_SERVER_NAME "\n" \
119     "    server_port=%%d      default: " DFL_SERVER_PORT "\n" \
120     "    debug_level=%%d      default: 0 (disabled)\n"        \
121     "    mode=%%d             default: 0 (SSL/TLS) (1 for STARTTLS)\n"  \
122     USAGE_AUTH                                                \
123     "    mail_from=%%s        default: \"\"\n"                \
124     "    mail_to=%%s          default: \"\"\n"                \
125     USAGE_IO                                                  \
126     "    force_ciphersuite=<name>    default: all enabled\n"  \
127     " acceptable ciphersuite names:\n"
128 
129 
130 /*
131  * global options
132  */
133 struct options
134 {
135     const char *server_name;    /* hostname of the server (client only)     */
136     const char *server_port;    /* port on which the ssl service runs       */
137     int debug_level;            /* level of debugging                       */
138     int authentication;         /* if authentication is required            */
139     int mode;                   /* SSL/TLS (0) or STARTTLS (1)              */
140     const char *user_name;      /* username to use for authentication       */
141     const char *user_pwd;       /* password to use for authentication       */
142     const char *mail_from;      /* E-Mail address to use as sender          */
143     const char *mail_to;        /* E-Mail address to use as recipient       */
144     const char *ca_file;        /* the file with the CA certificate(s)      */
145     const char *crt_file;       /* the file with the client certificate     */
146     const char *key_file;       /* the file with the client key             */
147     int force_ciphersuite[2];   /* protocol/ciphersuite to use, or all      */
148 } opt;
149 
my_debug(void * ctx,int level,const char * file,int line,const char * str)150 static void my_debug( void *ctx, int level,
151                       const char *file, int line,
152                       const char *str )
153 {
154     ((void) level);
155 
156     mbedtls_fprintf( (FILE *) ctx, "%s:%04d: %s", file, line, str );
157     fflush(  (FILE *) ctx  );
158 }
159 
do_handshake(mbedtls_ssl_context * ssl)160 static int do_handshake( mbedtls_ssl_context *ssl )
161 {
162     int ret;
163     uint32_t flags;
164     unsigned char buf[1024];
165     memset(buf, 0, 1024);
166 
167     /*
168      * 4. Handshake
169      */
170     mbedtls_printf( "  . Performing the SSL/TLS handshake..." );
171     fflush( stdout );
172 
173     while( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
174     {
175         if( ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE )
176         {
177 #if defined(MBEDTLS_ERROR_C)
178             mbedtls_strerror( ret, (char *) buf, 1024 );
179 #endif
180             mbedtls_printf( " failed\n  ! mbedtls_ssl_handshake returned %d: %s\n\n", ret, buf );
181             return( -1 );
182         }
183     }
184 
185     mbedtls_printf( " ok\n    [ Ciphersuite is %s ]\n",
186             mbedtls_ssl_get_ciphersuite( ssl ) );
187 
188     /*
189      * 5. Verify the server certificate
190      */
191     mbedtls_printf( "  . Verifying peer X.509 certificate..." );
192 
193     /* In real life, we probably want to bail out when ret != 0 */
194     if( ( flags = mbedtls_ssl_get_verify_result( ssl ) ) != 0 )
195     {
196 #if !defined(MBEDTLS_X509_REMOVE_INFO)
197         char vrfy_buf[512];
198 #endif
199 
200         mbedtls_printf( " failed\n" );
201 
202 #if !defined(MBEDTLS_X509_REMOVE_INFO)
203         mbedtls_x509_crt_verify_info( vrfy_buf, sizeof( vrfy_buf ), "  ! ", flags );
204 
205         mbedtls_printf( "%s\n", vrfy_buf );
206 #endif
207     }
208     else
209         mbedtls_printf( " ok\n" );
210 
211 #if !defined(MBEDTLS_X509_REMOVE_INFO)
212     mbedtls_printf( "  . Peer certificate information    ...\n" );
213     mbedtls_x509_crt_info( (char *) buf, sizeof( buf ) - 1, "      ",
214                    mbedtls_ssl_get_peer_cert( ssl ) );
215     mbedtls_printf( "%s\n", buf );
216 #endif
217 
218     return( 0 );
219 }
220 
write_ssl_data(mbedtls_ssl_context * ssl,unsigned char * buf,size_t len)221 static int write_ssl_data( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
222 {
223     int ret;
224 
225     mbedtls_printf("\n%s", buf);
226     while( len && ( ret = mbedtls_ssl_write( ssl, buf, len ) ) <= 0 )
227     {
228         if( ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE )
229         {
230             mbedtls_printf( " failed\n  ! mbedtls_ssl_write returned %d\n\n", ret );
231             return -1;
232         }
233     }
234 
235     return( 0 );
236 }
237 
write_ssl_and_get_response(mbedtls_ssl_context * ssl,unsigned char * buf,size_t len)238 static int write_ssl_and_get_response( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
239 {
240     int ret;
241     unsigned char data[128];
242     char code[4];
243     size_t i, idx = 0;
244 
245     mbedtls_printf("\n%s", buf);
246     while( len && ( ret = mbedtls_ssl_write( ssl, buf, len ) ) <= 0 )
247     {
248         if( ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE )
249         {
250             mbedtls_printf( " failed\n  ! mbedtls_ssl_write returned %d\n\n", ret );
251             return -1;
252         }
253     }
254 
255     do
256     {
257         len = sizeof( data ) - 1;
258         memset( data, 0, sizeof( data ) );
259         ret = mbedtls_ssl_read( ssl, data, len );
260 
261         if( ret == MBEDTLS_ERR_SSL_WANT_READ || ret == MBEDTLS_ERR_SSL_WANT_WRITE )
262             continue;
263 
264         if( ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY )
265             return -1;
266 
267         if( ret <= 0 )
268         {
269             mbedtls_printf( "failed\n  ! mbedtls_ssl_read returned %d\n\n", ret );
270             return -1;
271         }
272 
273         mbedtls_printf("\n%s", data);
274         len = ret;
275         for( i = 0; i < len; i++ )
276         {
277             if( data[i] != '\n' )
278             {
279                 if( idx < 4 )
280                     code[ idx++ ] = data[i];
281                 continue;
282             }
283 
284             if( idx == 4 && code[0] >= '0' && code[0] <= '9' && code[3] == ' ' )
285             {
286                 code[3] = '\0';
287                 return atoi( code );
288             }
289 
290             idx = 0;
291         }
292     }
293     while( 1 );
294 }
295 
write_and_get_response(mbedtls_net_context * sock_fd,unsigned char * buf,size_t len)296 static int write_and_get_response( mbedtls_net_context *sock_fd, unsigned char *buf, size_t len )
297 {
298     int ret;
299     unsigned char data[128];
300     char code[4];
301     size_t i, idx = 0;
302 
303     mbedtls_printf("\n%s", buf);
304     if( len && ( ret = mbedtls_net_send( sock_fd, buf, len ) ) <= 0 )
305     {
306         mbedtls_printf( " failed\n  ! mbedtls_net_send returned %d\n\n", ret );
307             return -1;
308     }
309 
310     do
311     {
312         len = sizeof( data ) - 1;
313         memset( data, 0, sizeof( data ) );
314         ret = mbedtls_net_recv( sock_fd, data, len );
315 
316         if( ret <= 0 )
317         {
318             mbedtls_printf( "failed\n  ! mbedtls_net_recv returned %d\n\n", ret );
319             return -1;
320         }
321 
322         data[len] = '\0';
323         mbedtls_printf("\n%s", data);
324         len = ret;
325         for( i = 0; i < len; i++ )
326         {
327             if( data[i] != '\n' )
328             {
329                 if( idx < 4 )
330                     code[ idx++ ] = data[i];
331                 continue;
332             }
333 
334             if( idx == 4 && code[0] >= '0' && code[0] <= '9' && code[3] == ' ' )
335             {
336                 code[3] = '\0';
337                 return atoi( code );
338             }
339 
340             idx = 0;
341         }
342     }
343     while( 1 );
344 }
345 
main(int argc,char * argv[])346 int main( int argc, char *argv[] )
347 {
348     int ret = 1, len;
349     int exit_code = MBEDTLS_EXIT_FAILURE;
350     mbedtls_net_context server_fd;
351 #if defined(MBEDTLS_BASE64_C)
352     unsigned char base[1024];
353     /* buf is used as the destination buffer for printing base with the format:
354      * "%s\r\n". Hence, the size of buf should be at least the size of base
355      * plus 2 bytes for the \r and \n characters.
356      */
357     unsigned char buf[sizeof( base ) + 2];
358 #else
359     unsigned char buf[1024];
360 #endif
361     char hostname[32];
362     const char *pers = "ssl_mail_client";
363 
364     mbedtls_entropy_context entropy;
365     mbedtls_ctr_drbg_context ctr_drbg;
366     mbedtls_ssl_context ssl;
367     mbedtls_ssl_config conf;
368     mbedtls_x509_crt cacert;
369     mbedtls_x509_crt clicert;
370     mbedtls_pk_context pkey;
371     int i;
372     size_t n;
373     char *p, *q;
374     const int *list;
375 
376     /*
377      * Make sure memory references are valid in case we exit early.
378      */
379     mbedtls_net_init( &server_fd );
380     mbedtls_ssl_init( &ssl );
381     mbedtls_ssl_config_init( &conf );
382     memset( &buf, 0, sizeof( buf ) );
383     mbedtls_x509_crt_init( &cacert );
384     mbedtls_x509_crt_init( &clicert );
385     mbedtls_pk_init( &pkey );
386     mbedtls_ctr_drbg_init( &ctr_drbg );
387 
388     if( argc == 0 )
389     {
390     usage:
391         mbedtls_printf( USAGE );
392 
393         list = mbedtls_ssl_list_ciphersuites();
394         while( *list )
395         {
396             mbedtls_printf("    %s\n", mbedtls_ssl_get_ciphersuite_name( *list ) );
397             list++;
398         }
399         mbedtls_printf("\n");
400         goto exit;
401     }
402 
403     opt.server_name         = DFL_SERVER_NAME;
404     opt.server_port         = DFL_SERVER_PORT;
405     opt.debug_level         = DFL_DEBUG_LEVEL;
406     opt.authentication      = DFL_AUTHENTICATION;
407     opt.mode                = DFL_MODE;
408     opt.user_name           = DFL_USER_NAME;
409     opt.user_pwd            = DFL_USER_PWD;
410     opt.mail_from           = DFL_MAIL_FROM;
411     opt.mail_to             = DFL_MAIL_TO;
412     opt.ca_file             = DFL_CA_FILE;
413     opt.crt_file            = DFL_CRT_FILE;
414     opt.key_file            = DFL_KEY_FILE;
415     opt.force_ciphersuite[0]= DFL_FORCE_CIPHER;
416 
417     for( i = 1; i < argc; i++ )
418     {
419         p = argv[i];
420         if( ( q = strchr( p, '=' ) ) == NULL )
421             goto usage;
422         *q++ = '\0';
423 
424         if( strcmp( p, "server_name" ) == 0 )
425             opt.server_name = q;
426         else if( strcmp( p, "server_port" ) == 0 )
427             opt.server_port = q;
428         else if( strcmp( p, "debug_level" ) == 0 )
429         {
430             opt.debug_level = atoi( q );
431             if( opt.debug_level < 0 || opt.debug_level > 65535 )
432                 goto usage;
433         }
434         else if( strcmp( p, "authentication" ) == 0 )
435         {
436             opt.authentication = atoi( q );
437             if( opt.authentication < 0 || opt.authentication > 1 )
438                 goto usage;
439         }
440         else if( strcmp( p, "mode" ) == 0 )
441         {
442             opt.mode = atoi( q );
443             if( opt.mode < 0 || opt.mode > 1 )
444                 goto usage;
445         }
446         else if( strcmp( p, "user_name" ) == 0 )
447             opt.user_name = q;
448         else if( strcmp( p, "user_pwd" ) == 0 )
449             opt.user_pwd = q;
450         else if( strcmp( p, "mail_from" ) == 0 )
451             opt.mail_from = q;
452         else if( strcmp( p, "mail_to" ) == 0 )
453             opt.mail_to = q;
454         else if( strcmp( p, "ca_file" ) == 0 )
455             opt.ca_file = q;
456         else if( strcmp( p, "crt_file" ) == 0 )
457             opt.crt_file = q;
458         else if( strcmp( p, "key_file" ) == 0 )
459             opt.key_file = q;
460         else if( strcmp( p, "force_ciphersuite" ) == 0 )
461         {
462             opt.force_ciphersuite[0] = -1;
463 
464             opt.force_ciphersuite[0] = mbedtls_ssl_get_ciphersuite_id( q );
465 
466             if( opt.force_ciphersuite[0] <= 0 )
467                 goto usage;
468 
469             opt.force_ciphersuite[1] = 0;
470         }
471         else
472             goto usage;
473     }
474 
475     /*
476      * 0. Initialize the RNG and the session data
477      */
478     mbedtls_printf( "\n  . Seeding the random number generator..." );
479     fflush( stdout );
480 
481     mbedtls_entropy_init( &entropy );
482     if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
483                                (const unsigned char *) pers,
484                                strlen( pers ) ) ) != 0 )
485     {
486         mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret );
487         goto exit;
488     }
489 
490     mbedtls_printf( " ok\n" );
491 
492     /*
493      * 1.1. Load the trusted CA
494      */
495     mbedtls_printf( "  . Loading the CA root certificate ..." );
496     fflush( stdout );
497 
498 #if defined(MBEDTLS_FS_IO)
499     if( strlen( opt.ca_file ) )
500         ret = mbedtls_x509_crt_parse_file( &cacert, opt.ca_file );
501     else
502 #endif
503 #if defined(MBEDTLS_PEM_PARSE_C)
504         ret = mbedtls_x509_crt_parse( &cacert, (const unsigned char *) mbedtls_test_cas_pem,
505                               mbedtls_test_cas_pem_len );
506 #else
507     {
508         mbedtls_printf("MBEDTLS_PEM_PARSE_C not defined.");
509         goto exit;
510     }
511 #endif
512     if( ret < 0 )
513     {
514         mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret );
515         goto exit;
516     }
517 
518     mbedtls_printf( " ok (%d skipped)\n", ret );
519 
520     /*
521      * 1.2. Load own certificate and private key
522      *
523      * (can be skipped if client authentication is not required)
524      */
525     mbedtls_printf( "  . Loading the client cert. and key..." );
526     fflush( stdout );
527 
528 #if defined(MBEDTLS_FS_IO)
529     if( strlen( opt.crt_file ) )
530         ret = mbedtls_x509_crt_parse_file( &clicert, opt.crt_file );
531     else
532 #endif
533         ret = mbedtls_x509_crt_parse( &clicert, (const unsigned char *) mbedtls_test_cli_crt,
534                               mbedtls_test_cli_crt_len );
535     if( ret != 0 )
536     {
537         mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret );
538         goto exit;
539     }
540 
541 #if defined(MBEDTLS_FS_IO)
542     if( strlen( opt.key_file ) )
543     {
544         ret = mbedtls_pk_parse_keyfile( &pkey, opt.key_file, "",
545                 mbedtls_ctr_drbg_random, &ctr_drbg );
546     }
547     else
548 #endif
549 #if defined(MBEDTLS_PEM_PARSE_C)
550     {
551         ret = mbedtls_pk_parse_key( &pkey, (const unsigned char *) mbedtls_test_cli_key,
552                 mbedtls_test_cli_key_len, NULL, 0, mbedtls_ctr_drbg_random, &ctr_drbg );
553     }
554 #else
555     {
556         mbedtls_printf("MBEDTLS_PEM_PARSE_C not defined.");
557         goto exit;
558     }
559 #endif
560     if( ret != 0 )
561     {
562         mbedtls_printf( " failed\n  !  mbedtls_pk_parse_key returned %d\n\n", ret );
563         goto exit;
564     }
565 
566     mbedtls_printf( " ok\n" );
567 
568     /*
569      * 2. Start the connection
570      */
571     mbedtls_printf( "  . Connecting to tcp/%s/%s...", opt.server_name,
572                                                 opt.server_port );
573     fflush( stdout );
574 
575     if( ( ret = mbedtls_net_connect( &server_fd, opt.server_name,
576                              opt.server_port, MBEDTLS_NET_PROTO_TCP ) ) != 0 )
577     {
578         mbedtls_printf( " failed\n  ! mbedtls_net_connect returned %d\n\n", ret );
579         goto exit;
580     }
581 
582     mbedtls_printf( " ok\n" );
583 
584     /*
585      * 3. Setup stuff
586      */
587     mbedtls_printf( "  . Setting up the SSL/TLS structure..." );
588     fflush( stdout );
589 
590     if( ( ret = mbedtls_ssl_config_defaults( &conf,
591                     MBEDTLS_SSL_IS_CLIENT,
592                     MBEDTLS_SSL_TRANSPORT_STREAM,
593                     MBEDTLS_SSL_PRESET_DEFAULT ) ) != 0 )
594     {
595         mbedtls_printf( " failed\n  ! mbedtls_ssl_config_defaults returned %d\n\n", ret );
596         goto exit;
597     }
598 
599     /* OPTIONAL is not optimal for security,
600      * but makes interop easier in this simplified example */
601     mbedtls_ssl_conf_authmode( &conf, MBEDTLS_SSL_VERIFY_OPTIONAL );
602 
603     mbedtls_ssl_conf_rng( &conf, mbedtls_ctr_drbg_random, &ctr_drbg );
604     mbedtls_ssl_conf_dbg( &conf, my_debug, stdout );
605 
606     if( opt.force_ciphersuite[0] != DFL_FORCE_CIPHER )
607         mbedtls_ssl_conf_ciphersuites( &conf, opt.force_ciphersuite );
608 
609     mbedtls_ssl_conf_ca_chain( &conf, &cacert, NULL );
610     if( ( ret = mbedtls_ssl_conf_own_cert( &conf, &clicert, &pkey ) ) != 0 )
611     {
612         mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_own_cert returned %d\n\n", ret );
613         goto exit;
614     }
615 
616     if( ( ret = mbedtls_ssl_setup( &ssl, &conf ) ) != 0 )
617     {
618         mbedtls_printf( " failed\n  ! mbedtls_ssl_setup returned %d\n\n", ret );
619         goto exit;
620     }
621 
622     if( ( ret = mbedtls_ssl_set_hostname( &ssl, opt.server_name ) ) != 0 )
623     {
624         mbedtls_printf( " failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n", ret );
625         goto exit;
626     }
627 
628     mbedtls_ssl_set_bio( &ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv, NULL );
629 
630     mbedtls_printf( " ok\n" );
631 
632     if( opt.mode == MODE_SSL_TLS )
633     {
634         if( do_handshake( &ssl ) != 0 )
635             goto exit;
636 
637         mbedtls_printf( "  > Get header from server:" );
638         fflush( stdout );
639 
640         ret = write_ssl_and_get_response( &ssl, buf, 0 );
641         if( ret < 200 || ret > 299 )
642         {
643             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
644             goto exit;
645         }
646 
647         mbedtls_printf(" ok\n" );
648 
649         mbedtls_printf( "  > Write EHLO to server:" );
650         fflush( stdout );
651 
652         gethostname( hostname, 32 );
653         len = sprintf( (char *) buf, "EHLO %s\r\n", hostname );
654         ret = write_ssl_and_get_response( &ssl, buf, len );
655         if( ret < 200 || ret > 299 )
656         {
657             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
658             goto exit;
659         }
660     }
661     else
662     {
663         mbedtls_printf( "  > Get header from server:" );
664         fflush( stdout );
665 
666         ret = write_and_get_response( &server_fd, buf, 0 );
667         if( ret < 200 || ret > 299 )
668         {
669             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
670             goto exit;
671         }
672 
673         mbedtls_printf(" ok\n" );
674 
675         mbedtls_printf( "  > Write EHLO to server:" );
676         fflush( stdout );
677 
678         gethostname( hostname, 32 );
679         len = sprintf( (char *) buf, "EHLO %s\r\n", hostname );
680         ret = write_and_get_response( &server_fd, buf, len );
681         if( ret < 200 || ret > 299 )
682         {
683             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
684             goto exit;
685         }
686 
687         mbedtls_printf(" ok\n" );
688 
689         mbedtls_printf( "  > Write STARTTLS to server:" );
690         fflush( stdout );
691 
692         gethostname( hostname, 32 );
693         len = sprintf( (char *) buf, "STARTTLS\r\n" );
694         ret = write_and_get_response( &server_fd, buf, len );
695         if( ret < 200 || ret > 299 )
696         {
697             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
698             goto exit;
699         }
700 
701         mbedtls_printf(" ok\n" );
702 
703         if( do_handshake( &ssl ) != 0 )
704             goto exit;
705     }
706 
707 #if defined(MBEDTLS_BASE64_C)
708     if( opt.authentication )
709     {
710         mbedtls_printf( "  > Write AUTH LOGIN to server:" );
711         fflush( stdout );
712 
713         len = sprintf( (char *) buf, "AUTH LOGIN\r\n" );
714         ret = write_ssl_and_get_response( &ssl, buf, len );
715         if( ret < 200 || ret > 399 )
716         {
717             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
718             goto exit;
719         }
720 
721         mbedtls_printf(" ok\n" );
722 
723         mbedtls_printf( "  > Write username to server: %s", opt.user_name );
724         fflush( stdout );
725 
726         ret = mbedtls_base64_encode( base, sizeof( base ), &n, (const unsigned char *) opt.user_name,
727                              strlen( opt.user_name ) );
728 
729         if( ret != 0 ) {
730             mbedtls_printf( " failed\n  ! mbedtls_base64_encode returned %d\n\n", ret );
731             goto exit;
732         }
733         len = sprintf( (char *) buf, "%s\r\n", base );
734         ret = write_ssl_and_get_response( &ssl, buf, len );
735         if( ret < 300 || ret > 399 )
736         {
737             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
738             goto exit;
739         }
740 
741         mbedtls_printf(" ok\n" );
742 
743         mbedtls_printf( "  > Write password to server: %s", opt.user_pwd );
744         fflush( stdout );
745 
746         ret = mbedtls_base64_encode( base, sizeof( base ), &n, (const unsigned char *) opt.user_pwd,
747                              strlen( opt.user_pwd ) );
748 
749         if( ret != 0 ) {
750             mbedtls_printf( " failed\n  ! mbedtls_base64_encode returned %d\n\n", ret );
751             goto exit;
752         }
753         len = sprintf( (char *) buf, "%s\r\n", base );
754         ret = write_ssl_and_get_response( &ssl, buf, len );
755         if( ret < 200 || ret > 399 )
756         {
757             mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
758             goto exit;
759         }
760 
761         mbedtls_printf(" ok\n" );
762     }
763 #endif
764 
765     mbedtls_printf( "  > Write MAIL FROM to server:" );
766     fflush( stdout );
767 
768     len = sprintf( (char *) buf, "MAIL FROM:<%s>\r\n", opt.mail_from );
769     ret = write_ssl_and_get_response( &ssl, buf, len );
770     if( ret < 200 || ret > 299 )
771     {
772         mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
773         goto exit;
774     }
775 
776     mbedtls_printf(" ok\n" );
777 
778     mbedtls_printf( "  > Write RCPT TO to server:" );
779     fflush( stdout );
780 
781     len = sprintf( (char *) buf, "RCPT TO:<%s>\r\n", opt.mail_to );
782     ret = write_ssl_and_get_response( &ssl, buf, len );
783     if( ret < 200 || ret > 299 )
784     {
785         mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
786         goto exit;
787     }
788 
789     mbedtls_printf(" ok\n" );
790 
791     mbedtls_printf( "  > Write DATA to server:" );
792     fflush( stdout );
793 
794     len = sprintf( (char *) buf, "DATA\r\n" );
795     ret = write_ssl_and_get_response( &ssl, buf, len );
796     if( ret < 300 || 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     mbedtls_printf( "  > Write content to server:" );
805     fflush( stdout );
806 
807     len = sprintf( (char *) buf, "From: %s\r\nSubject: mbed TLS Test mail\r\n\r\n"
808             "This is a simple test mail from the "
809             "mbed TLS mail client example.\r\n"
810             "\r\n"
811             "Enjoy!", opt.mail_from );
812     ret = write_ssl_data( &ssl, buf, len );
813 
814     len = sprintf( (char *) buf, "\r\n.\r\n");
815     ret = write_ssl_and_get_response( &ssl, buf, len );
816     if( ret < 200 || ret > 299 )
817     {
818         mbedtls_printf( " failed\n  ! server responded with %d\n\n", ret );
819         goto exit;
820     }
821 
822     mbedtls_printf(" ok\n" );
823 
824     mbedtls_ssl_close_notify( &ssl );
825 
826     exit_code = MBEDTLS_EXIT_SUCCESS;
827 
828 exit:
829 
830     mbedtls_net_free( &server_fd );
831     mbedtls_x509_crt_free( &clicert );
832     mbedtls_x509_crt_free( &cacert );
833     mbedtls_pk_free( &pkey );
834     mbedtls_ssl_free( &ssl );
835     mbedtls_ssl_config_free( &conf );
836     mbedtls_ctr_drbg_free( &ctr_drbg );
837     mbedtls_entropy_free( &entropy );
838 
839     mbedtls_exit( exit_code );
840 }
841 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ENTROPY_C && MBEDTLS_SSL_TLS_C &&
842           MBEDTLS_SSL_CLI_C && MBEDTLS_NET_C && MBEDTLS_RSA_C **
843           MBEDTLS_CTR_DRBG_C */
844