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