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1 /*
2  *  Simple DTLS server demonstration program
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 #include "mbedtls/build_info.h"
21 
22 #include "mbedtls/platform.h"
23 
24 /* Uncomment out the following line to default to IPv4 and disable IPv6 */
25 //#define FORCE_IPV4
26 
27 #ifdef FORCE_IPV4
28 #define BIND_IP     "0.0.0.0"     /* Forces IPv4 */
29 #else
30 #define BIND_IP     "::"
31 #endif
32 
33 #if !defined(MBEDTLS_SSL_SRV_C) || !defined(MBEDTLS_SSL_PROTO_DTLS) ||    \
34     !defined(MBEDTLS_SSL_COOKIE_C) || !defined(MBEDTLS_NET_C) ||          \
35     !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C) ||        \
36     !defined(MBEDTLS_X509_CRT_PARSE_C) || !defined(MBEDTLS_RSA_C) ||      \
37     !defined(MBEDTLS_PEM_PARSE_C) || !defined(MBEDTLS_TIMING_C)
38 
main(void)39 int main(void)
40 {
41     printf("MBEDTLS_SSL_SRV_C and/or MBEDTLS_SSL_PROTO_DTLS and/or "
42            "MBEDTLS_SSL_COOKIE_C and/or MBEDTLS_NET_C and/or "
43            "MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C and/or "
44            "MBEDTLS_X509_CRT_PARSE_C and/or MBEDTLS_RSA_C and/or "
45            "MBEDTLS_PEM_PARSE_C and/or MBEDTLS_TIMING_C not defined.\n");
46     mbedtls_exit(0);
47 }
48 #else
49 
50 #if defined(_WIN32)
51 #include <windows.h>
52 #endif
53 
54 #include <string.h>
55 #include <stdlib.h>
56 #include <stdio.h>
57 
58 #include "mbedtls/entropy.h"
59 #include "mbedtls/ctr_drbg.h"
60 #include "mbedtls/x509.h"
61 #include "mbedtls/ssl.h"
62 #include "mbedtls/ssl_cookie.h"
63 #include "mbedtls/net_sockets.h"
64 #include "mbedtls/error.h"
65 #include "mbedtls/debug.h"
66 #include "mbedtls/timing.h"
67 
68 #include "test/certs.h"
69 
70 #if defined(MBEDTLS_SSL_CACHE_C)
71 #include "mbedtls/ssl_cache.h"
72 #endif
73 
74 #define READ_TIMEOUT_MS 10000   /* 10 seconds */
75 #define DEBUG_LEVEL 0
76 
77 
my_debug(void * ctx,int level,const char * file,int line,const char * str)78 static void my_debug(void *ctx, int level,
79                      const char *file, int line,
80                      const char *str)
81 {
82     ((void) level);
83 
84     mbedtls_fprintf((FILE *) ctx, "%s:%04d: %s", file, line, str);
85     fflush((FILE *) ctx);
86 }
87 
main(void)88 int main(void)
89 {
90     int ret, len;
91     mbedtls_net_context listen_fd, client_fd;
92     unsigned char buf[1024];
93     const char *pers = "dtls_server";
94     unsigned char client_ip[16] = { 0 };
95     size_t cliip_len;
96     mbedtls_ssl_cookie_ctx cookie_ctx;
97 
98     mbedtls_entropy_context entropy;
99     mbedtls_ctr_drbg_context ctr_drbg;
100     mbedtls_ssl_context ssl;
101     mbedtls_ssl_config conf;
102     mbedtls_x509_crt srvcert;
103     mbedtls_pk_context pkey;
104     mbedtls_timing_delay_context timer;
105 #if defined(MBEDTLS_SSL_CACHE_C)
106     mbedtls_ssl_cache_context cache;
107 #endif
108 
109     mbedtls_net_init(&listen_fd);
110     mbedtls_net_init(&client_fd);
111     mbedtls_ssl_init(&ssl);
112     mbedtls_ssl_config_init(&conf);
113     mbedtls_ssl_cookie_init(&cookie_ctx);
114 #if defined(MBEDTLS_SSL_CACHE_C)
115     mbedtls_ssl_cache_init(&cache);
116 #endif
117     mbedtls_x509_crt_init(&srvcert);
118     mbedtls_pk_init(&pkey);
119     mbedtls_entropy_init(&entropy);
120     mbedtls_ctr_drbg_init(&ctr_drbg);
121 
122 #if defined(MBEDTLS_DEBUG_C)
123     mbedtls_debug_set_threshold(DEBUG_LEVEL);
124 #endif
125 
126     /*
127      * 1. Seed the RNG
128      */
129     printf("  . Seeding the random number generator...");
130     fflush(stdout);
131 
132     if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
133                                      (const unsigned char *) pers,
134                                      strlen(pers))) != 0) {
135         printf(" failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret);
136         goto exit;
137     }
138 
139     printf(" ok\n");
140 
141     /*
142      * 2. Load the certificates and private RSA key
143      */
144     printf("\n  . Loading the server cert. and key...");
145     fflush(stdout);
146 
147     /*
148      * This demonstration program uses embedded test certificates.
149      * Instead, you may want to use mbedtls_x509_crt_parse_file() to read the
150      * server and CA certificates, as well as mbedtls_pk_parse_keyfile().
151      */
152     ret = mbedtls_x509_crt_parse(&srvcert, (const unsigned char *) mbedtls_test_srv_crt,
153                                  mbedtls_test_srv_crt_len);
154     if (ret != 0) {
155         printf(" failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret);
156         goto exit;
157     }
158 
159     ret = mbedtls_x509_crt_parse(&srvcert, (const unsigned char *) mbedtls_test_cas_pem,
160                                  mbedtls_test_cas_pem_len);
161     if (ret != 0) {
162         printf(" failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret);
163         goto exit;
164     }
165 
166     ret =  mbedtls_pk_parse_key(&pkey,
167                                 (const unsigned char *) mbedtls_test_srv_key,
168                                 mbedtls_test_srv_key_len,
169                                 NULL,
170                                 0,
171                                 mbedtls_ctr_drbg_random,
172                                 &ctr_drbg);
173     if (ret != 0) {
174         printf(" failed\n  !  mbedtls_pk_parse_key returned %d\n\n", ret);
175         goto exit;
176     }
177 
178     printf(" ok\n");
179 
180     /*
181      * 3. Setup the "listening" UDP socket
182      */
183     printf("  . Bind on udp/*/4433 ...");
184     fflush(stdout);
185 
186     if ((ret = mbedtls_net_bind(&listen_fd, BIND_IP, "4433", MBEDTLS_NET_PROTO_UDP)) != 0) {
187         printf(" failed\n  ! mbedtls_net_bind returned %d\n\n", ret);
188         goto exit;
189     }
190 
191     printf(" ok\n");
192 
193     /*
194      * 4. Setup stuff
195      */
196     printf("  . Setting up the DTLS data...");
197     fflush(stdout);
198 
199     if ((ret = mbedtls_ssl_config_defaults(&conf,
200                                            MBEDTLS_SSL_IS_SERVER,
201                                            MBEDTLS_SSL_TRANSPORT_DATAGRAM,
202                                            MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
203         mbedtls_printf(" failed\n  ! mbedtls_ssl_config_defaults returned %d\n\n", ret);
204         goto exit;
205     }
206 
207     mbedtls_ssl_conf_rng(&conf, mbedtls_ctr_drbg_random, &ctr_drbg);
208     mbedtls_ssl_conf_dbg(&conf, my_debug, stdout);
209     mbedtls_ssl_conf_read_timeout(&conf, READ_TIMEOUT_MS);
210 
211 #if defined(MBEDTLS_SSL_CACHE_C)
212     mbedtls_ssl_conf_session_cache(&conf, &cache,
213                                    mbedtls_ssl_cache_get,
214                                    mbedtls_ssl_cache_set);
215 #endif
216 
217     mbedtls_ssl_conf_ca_chain(&conf, srvcert.next, NULL);
218     if ((ret = mbedtls_ssl_conf_own_cert(&conf, &srvcert, &pkey)) != 0) {
219         printf(" failed\n  ! mbedtls_ssl_conf_own_cert returned %d\n\n", ret);
220         goto exit;
221     }
222 
223     if ((ret = mbedtls_ssl_cookie_setup(&cookie_ctx,
224                                         mbedtls_ctr_drbg_random, &ctr_drbg)) != 0) {
225         printf(" failed\n  ! mbedtls_ssl_cookie_setup returned %d\n\n", ret);
226         goto exit;
227     }
228 
229     mbedtls_ssl_conf_dtls_cookies(&conf, mbedtls_ssl_cookie_write, mbedtls_ssl_cookie_check,
230                                   &cookie_ctx);
231 
232     if ((ret = mbedtls_ssl_setup(&ssl, &conf)) != 0) {
233         printf(" failed\n  ! mbedtls_ssl_setup returned %d\n\n", ret);
234         goto exit;
235     }
236 
237     mbedtls_ssl_set_timer_cb(&ssl, &timer, mbedtls_timing_set_delay,
238                              mbedtls_timing_get_delay);
239 
240     printf(" ok\n");
241 
242 reset:
243 #ifdef MBEDTLS_ERROR_C
244     if (ret != 0) {
245         char error_buf[100];
246         mbedtls_strerror(ret, error_buf, 100);
247         printf("Last error was: %d - %s\n\n", ret, error_buf);
248     }
249 #endif
250 
251     mbedtls_net_free(&client_fd);
252 
253     mbedtls_ssl_session_reset(&ssl);
254 
255     /*
256      * 3. Wait until a client connects
257      */
258     printf("  . Waiting for a remote connection ...");
259     fflush(stdout);
260 
261     if ((ret = mbedtls_net_accept(&listen_fd, &client_fd,
262                                   client_ip, sizeof(client_ip), &cliip_len)) != 0) {
263         printf(" failed\n  ! mbedtls_net_accept returned %d\n\n", ret);
264         goto exit;
265     }
266 
267     /* For HelloVerifyRequest cookies */
268     if ((ret = mbedtls_ssl_set_client_transport_id(&ssl,
269                                                    client_ip, cliip_len)) != 0) {
270         printf(" failed\n  ! "
271                "mbedtls_ssl_set_client_transport_id() returned -0x%x\n\n", (unsigned int) -ret);
272         goto exit;
273     }
274 
275     mbedtls_ssl_set_bio(&ssl, &client_fd,
276                         mbedtls_net_send, mbedtls_net_recv, mbedtls_net_recv_timeout);
277 
278     printf(" ok\n");
279 
280     /*
281      * 5. Handshake
282      */
283     printf("  . Performing the DTLS handshake...");
284     fflush(stdout);
285 
286     do {
287         ret = mbedtls_ssl_handshake(&ssl);
288     } while (ret == MBEDTLS_ERR_SSL_WANT_READ ||
289              ret == MBEDTLS_ERR_SSL_WANT_WRITE);
290 
291     if (ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED) {
292         printf(" hello verification requested\n");
293         ret = 0;
294         goto reset;
295     } else if (ret != 0) {
296         printf(" failed\n  ! mbedtls_ssl_handshake returned -0x%x\n\n", (unsigned int) -ret);
297         goto reset;
298     }
299 
300     printf(" ok\n");
301 
302     /*
303      * 6. Read the echo Request
304      */
305     printf("  < Read from client:");
306     fflush(stdout);
307 
308     len = sizeof(buf) - 1;
309     memset(buf, 0, sizeof(buf));
310 
311     do {
312         ret = mbedtls_ssl_read(&ssl, buf, len);
313     } while (ret == MBEDTLS_ERR_SSL_WANT_READ ||
314              ret == MBEDTLS_ERR_SSL_WANT_WRITE);
315 
316     if (ret <= 0) {
317         switch (ret) {
318             case MBEDTLS_ERR_SSL_TIMEOUT:
319                 printf(" timeout\n\n");
320                 goto reset;
321 
322             case MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY:
323                 printf(" connection was closed gracefully\n");
324                 ret = 0;
325                 goto close_notify;
326 
327             default:
328                 printf(" mbedtls_ssl_read returned -0x%x\n\n", (unsigned int) -ret);
329                 goto reset;
330         }
331     }
332 
333     len = ret;
334     printf(" %d bytes read\n\n%s\n\n", len, buf);
335 
336     /*
337      * 7. Write the 200 Response
338      */
339     printf("  > Write to client:");
340     fflush(stdout);
341 
342     do {
343         ret = mbedtls_ssl_write(&ssl, buf, len);
344     } while (ret == MBEDTLS_ERR_SSL_WANT_READ ||
345              ret == MBEDTLS_ERR_SSL_WANT_WRITE);
346 
347     if (ret < 0) {
348         printf(" failed\n  ! mbedtls_ssl_write returned %d\n\n", ret);
349         goto exit;
350     }
351 
352     len = ret;
353     printf(" %d bytes written\n\n%s\n\n", len, buf);
354 
355     /*
356      * 8. Done, cleanly close the connection
357      */
358 close_notify:
359     printf("  . Closing the connection...");
360 
361     /* No error checking, the connection might be closed already */
362     do {
363         ret = mbedtls_ssl_close_notify(&ssl);
364     } while (ret == MBEDTLS_ERR_SSL_WANT_WRITE);
365     ret = 0;
366 
367     printf(" done\n");
368 
369     goto reset;
370 
371     /*
372      * Final clean-ups and exit
373      */
374 exit:
375 
376 #ifdef MBEDTLS_ERROR_C
377     if (ret != 0) {
378         char error_buf[100];
379         mbedtls_strerror(ret, error_buf, 100);
380         printf("Last error was: %d - %s\n\n", ret, error_buf);
381     }
382 #endif
383 
384     mbedtls_net_free(&client_fd);
385     mbedtls_net_free(&listen_fd);
386 
387     mbedtls_x509_crt_free(&srvcert);
388     mbedtls_pk_free(&pkey);
389     mbedtls_ssl_free(&ssl);
390     mbedtls_ssl_config_free(&conf);
391     mbedtls_ssl_cookie_free(&cookie_ctx);
392 #if defined(MBEDTLS_SSL_CACHE_C)
393     mbedtls_ssl_cache_free(&cache);
394 #endif
395     mbedtls_ctr_drbg_free(&ctr_drbg);
396     mbedtls_entropy_free(&entropy);
397 
398     /* Shell can not handle large exit numbers -> 1 for errors */
399     if (ret < 0) {
400         ret = 1;
401     }
402 
403     mbedtls_exit(ret);
404 }
405 #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_DTLS &&
406           MBEDTLS_SSL_COOKIE_C && MBEDTLS_NET_C && MBEDTLS_ENTROPY_C &&
407           MBEDTLS_CTR_DRBG_C && MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_RSA_C
408           && MBEDTLS_PEM_PARSE_C && MBEDTLS_TIMING_C */
409