1 /*
2 * UDP proxy: emulate an unreliable UDP connection for DTLS testing
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6 */
7
8 /*
9 * Warning: this is an internal utility program we use for tests.
10 * It does break some abstractions from the NET layer, and is thus NOT an
11 * example of good general usage.
12 */
13
14
15 #include "mbedtls/build_info.h"
16
17 #if defined(MBEDTLS_PLATFORM_C)
18 #include "mbedtls/platform.h"
19 #else
20 #include <stdio.h>
21 #include <stdlib.h>
22 #if defined(MBEDTLS_HAVE_TIME)
23 #include <time.h>
24 #define mbedtls_time time
25 #define mbedtls_time_t time_t
26 #endif
27 #define mbedtls_printf printf
28 #define mbedtls_calloc calloc
29 #define mbedtls_free free
30 #define mbedtls_exit exit
31 #define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
32 #define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
33 #endif /* MBEDTLS_PLATFORM_C */
34
35 #if !defined(MBEDTLS_NET_C)
main(void)36 int main(void)
37 {
38 mbedtls_printf("MBEDTLS_NET_C not defined.\n");
39 mbedtls_exit(0);
40 }
41 #else
42
43 #include "mbedtls/net_sockets.h"
44 #include "mbedtls/error.h"
45 #include "mbedtls/ssl.h"
46 #include "mbedtls/timing.h"
47
48 #include <string.h>
49
50 /* For select() */
51 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
52 !defined(EFI32)
53 #include <winsock2.h>
54 #include <windows.h>
55 #if defined(_MSC_VER)
56 #if defined(_WIN32_WCE)
57 #pragma comment( lib, "ws2.lib" )
58 #else
59 #pragma comment( lib, "ws2_32.lib" )
60 #endif
61 #endif /* _MSC_VER */
62 #else /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */
63 #if defined(MBEDTLS_HAVE_TIME) || (defined(MBEDTLS_TIMING_C) && !defined(MBEDTLS_TIMING_ALT))
64 #include <sys/time.h>
65 #endif
66 #include <sys/select.h>
67 #include <sys/types.h>
68 #include <unistd.h>
69 #endif /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */
70
71 #define MAX_MSG_SIZE 16384 + 2048 /* max record/datagram size */
72
73 #define DFL_SERVER_ADDR "localhost"
74 #define DFL_SERVER_PORT "4433"
75 #define DFL_LISTEN_ADDR "localhost"
76 #define DFL_LISTEN_PORT "5556"
77 #define DFL_PACK 0
78
79 #if defined(MBEDTLS_TIMING_C)
80 #define USAGE_PACK \
81 " pack=%%d default: 0 (don't pack)\n" \
82 " options: t > 0 (pack for t milliseconds)\n"
83 #else
84 #define USAGE_PACK
85 #endif
86
87 #define USAGE \
88 "\n usage: udp_proxy param=<>...\n" \
89 "\n acceptable parameters:\n" \
90 " server_addr=%%s default: localhost\n" \
91 " server_port=%%d default: 4433\n" \
92 " listen_addr=%%s default: localhost\n" \
93 " listen_port=%%d default: 4433\n" \
94 "\n" \
95 " duplicate=%%d default: 0 (no duplication)\n" \
96 " duplicate about 1:N packets randomly\n" \
97 " delay=%%d default: 0 (no delayed packets)\n" \
98 " delay about 1:N packets randomly\n" \
99 " delay_ccs=0/1 default: 0 (don't delay ChangeCipherSpec)\n" \
100 " delay_cli=%%s Handshake message from client that should be\n" \
101 " delayed. Possible values are 'ClientHello',\n" \
102 " 'Certificate', 'CertificateVerify', and\n" \
103 " 'ClientKeyExchange'.\n" \
104 " May be used multiple times, even for the same\n" \
105 " message, in which case the respective message\n" \
106 " gets delayed multiple times.\n" \
107 " delay_srv=%%s Handshake message from server that should be\n" \
108 " delayed. Possible values are 'HelloRequest',\n" \
109 " 'ServerHello', 'ServerHelloDone', 'Certificate'\n" \
110 " 'ServerKeyExchange', 'NewSessionTicket',\n" \
111 " 'HelloVerifyRequest' and ''CertificateRequest'.\n" \
112 " May be used multiple times, even for the same\n" \
113 " message, in which case the respective message\n" \
114 " gets delayed multiple times.\n" \
115 " drop=%%d default: 0 (no dropped packets)\n" \
116 " drop about 1:N packets randomly\n" \
117 " mtu=%%d default: 0 (unlimited)\n" \
118 " drop packets larger than N bytes\n" \
119 " bad_ad=0/1 default: 0 (don't add bad ApplicationData)\n" \
120 " bad_cid=%%d default: 0 (don't corrupt Connection IDs)\n" \
121 " duplicate 1:N packets containing a CID,\n" \
122 " modifying CID in first instance of the packet.\n" \
123 " protect_hvr=0/1 default: 0 (don't protect HelloVerifyRequest)\n" \
124 " protect_len=%%d default: (don't protect packets of this size)\n" \
125 " inject_clihlo=0/1 default: 0 (don't inject fake ClientHello)\n" \
126 "\n" \
127 " seed=%%d default: (use current time)\n" \
128 USAGE_PACK \
129 "\n"
130
131 /*
132 * global options
133 */
134
135 #define MAX_DELAYED_HS 10
136
137 static struct options {
138 const char *server_addr; /* address to forward packets to */
139 const char *server_port; /* port to forward packets to */
140 const char *listen_addr; /* address for accepting client connections */
141 const char *listen_port; /* port for accepting client connections */
142
143 int duplicate; /* duplicate 1 in N packets (none if 0) */
144 int delay; /* delay 1 packet in N (none if 0) */
145 int delay_ccs; /* delay ChangeCipherSpec */
146 char *delay_cli[MAX_DELAYED_HS]; /* handshake types of messages from
147 * client that should be delayed. */
148 uint8_t delay_cli_cnt; /* Number of entries in delay_cli. */
149 char *delay_srv[MAX_DELAYED_HS]; /* handshake types of messages from
150 * server that should be delayed. */
151 uint8_t delay_srv_cnt; /* Number of entries in delay_srv. */
152 int drop; /* drop 1 packet in N (none if 0) */
153 int mtu; /* drop packets larger than this */
154 int bad_ad; /* inject corrupted ApplicationData record */
155 unsigned bad_cid; /* inject corrupted CID record */
156 int protect_hvr; /* never drop or delay HelloVerifyRequest */
157 int protect_len; /* never drop/delay packet of the given size*/
158 int inject_clihlo; /* inject fake ClientHello after handshake */
159 unsigned pack; /* merge packets into single datagram for
160 * at most \c merge milliseconds if > 0 */
161 unsigned int seed; /* seed for "random" events */
162 } opt;
163
exit_usage(const char * name,const char * value)164 static void exit_usage(const char *name, const char *value)
165 {
166 if (value == NULL) {
167 mbedtls_printf(" unknown option or missing value: %s\n", name);
168 } else {
169 mbedtls_printf(" option %s: illegal value: %s\n", name, value);
170 }
171
172 mbedtls_printf(USAGE);
173 mbedtls_exit(1);
174 }
175
get_options(int argc,char * argv[])176 static void get_options(int argc, char *argv[])
177 {
178 int i;
179 char *p, *q;
180
181 opt.server_addr = DFL_SERVER_ADDR;
182 opt.server_port = DFL_SERVER_PORT;
183 opt.listen_addr = DFL_LISTEN_ADDR;
184 opt.listen_port = DFL_LISTEN_PORT;
185 opt.pack = DFL_PACK;
186 /* Other members default to 0 */
187
188 opt.delay_cli_cnt = 0;
189 opt.delay_srv_cnt = 0;
190 memset(opt.delay_cli, 0, sizeof(opt.delay_cli));
191 memset(opt.delay_srv, 0, sizeof(opt.delay_srv));
192
193 for (i = 1; i < argc; i++) {
194 p = argv[i];
195 if ((q = strchr(p, '=')) == NULL) {
196 exit_usage(p, NULL);
197 }
198 *q++ = '\0';
199
200 if (strcmp(p, "server_addr") == 0) {
201 opt.server_addr = q;
202 } else if (strcmp(p, "server_port") == 0) {
203 opt.server_port = q;
204 } else if (strcmp(p, "listen_addr") == 0) {
205 opt.listen_addr = q;
206 } else if (strcmp(p, "listen_port") == 0) {
207 opt.listen_port = q;
208 } else if (strcmp(p, "duplicate") == 0) {
209 opt.duplicate = atoi(q);
210 if (opt.duplicate < 0 || opt.duplicate > 20) {
211 exit_usage(p, q);
212 }
213 } else if (strcmp(p, "delay") == 0) {
214 opt.delay = atoi(q);
215 if (opt.delay < 0 || opt.delay > 20 || opt.delay == 1) {
216 exit_usage(p, q);
217 }
218 } else if (strcmp(p, "delay_ccs") == 0) {
219 opt.delay_ccs = atoi(q);
220 if (opt.delay_ccs < 0 || opt.delay_ccs > 1) {
221 exit_usage(p, q);
222 }
223 } else if (strcmp(p, "delay_cli") == 0 ||
224 strcmp(p, "delay_srv") == 0) {
225 uint8_t *delay_cnt;
226 char **delay_list;
227 size_t len;
228 char *buf;
229
230 if (strcmp(p, "delay_cli") == 0) {
231 delay_cnt = &opt.delay_cli_cnt;
232 delay_list = opt.delay_cli;
233 } else {
234 delay_cnt = &opt.delay_srv_cnt;
235 delay_list = opt.delay_srv;
236 }
237
238 if (*delay_cnt == MAX_DELAYED_HS) {
239 mbedtls_printf(" too many uses of %s: only %d allowed\n",
240 p, MAX_DELAYED_HS);
241 exit_usage(p, NULL);
242 }
243
244 len = strlen(q);
245 buf = mbedtls_calloc(1, len + 1);
246 if (buf == NULL) {
247 mbedtls_printf(" Allocation failure\n");
248 exit(1);
249 }
250 memcpy(buf, q, len + 1);
251
252 delay_list[(*delay_cnt)++] = buf;
253 } else if (strcmp(p, "drop") == 0) {
254 opt.drop = atoi(q);
255 if (opt.drop < 0 || opt.drop > 20 || opt.drop == 1) {
256 exit_usage(p, q);
257 }
258 } else if (strcmp(p, "pack") == 0) {
259 #if defined(MBEDTLS_TIMING_C)
260 opt.pack = (unsigned) atoi(q);
261 #else
262 mbedtls_printf(" option pack only defined if MBEDTLS_TIMING_C is enabled\n");
263 exit(1);
264 #endif
265 } else if (strcmp(p, "mtu") == 0) {
266 opt.mtu = atoi(q);
267 if (opt.mtu < 0 || opt.mtu > MAX_MSG_SIZE) {
268 exit_usage(p, q);
269 }
270 } else if (strcmp(p, "bad_ad") == 0) {
271 opt.bad_ad = atoi(q);
272 if (opt.bad_ad < 0 || opt.bad_ad > 1) {
273 exit_usage(p, q);
274 }
275 }
276 #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
277 else if (strcmp(p, "bad_cid") == 0) {
278 opt.bad_cid = (unsigned) atoi(q);
279 }
280 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
281 else if (strcmp(p, "protect_hvr") == 0) {
282 opt.protect_hvr = atoi(q);
283 if (opt.protect_hvr < 0 || opt.protect_hvr > 1) {
284 exit_usage(p, q);
285 }
286 } else if (strcmp(p, "protect_len") == 0) {
287 opt.protect_len = atoi(q);
288 if (opt.protect_len < 0) {
289 exit_usage(p, q);
290 }
291 } else if (strcmp(p, "inject_clihlo") == 0) {
292 opt.inject_clihlo = atoi(q);
293 if (opt.inject_clihlo < 0 || opt.inject_clihlo > 1) {
294 exit_usage(p, q);
295 }
296 } else if (strcmp(p, "seed") == 0) {
297 opt.seed = atoi(q);
298 if (opt.seed == 0) {
299 exit_usage(p, q);
300 }
301 } else {
302 exit_usage(p, NULL);
303 }
304 }
305 }
306
msg_type(unsigned char * msg,size_t len)307 static const char *msg_type(unsigned char *msg, size_t len)
308 {
309 if (len < 1) {
310 return "Invalid";
311 }
312 switch (msg[0]) {
313 case MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC: return "ChangeCipherSpec";
314 case MBEDTLS_SSL_MSG_ALERT: return "Alert";
315 case MBEDTLS_SSL_MSG_APPLICATION_DATA: return "ApplicationData";
316 case MBEDTLS_SSL_MSG_CID: return "CID";
317 case MBEDTLS_SSL_MSG_HANDSHAKE: break; /* See below */
318 default: return "Unknown";
319 }
320
321 if (len < 13 + 12) {
322 return "Invalid handshake";
323 }
324
325 /*
326 * Our handshake message are less than 2^16 bytes long, so they should
327 * have 0 as the first byte of length, frag_offset and frag_length.
328 * Otherwise, assume they are encrypted.
329 */
330 if (msg[14] || msg[19] || msg[22]) {
331 return "Encrypted handshake";
332 }
333
334 switch (msg[13]) {
335 case MBEDTLS_SSL_HS_HELLO_REQUEST: return "HelloRequest";
336 case MBEDTLS_SSL_HS_CLIENT_HELLO: return "ClientHello";
337 case MBEDTLS_SSL_HS_SERVER_HELLO: return "ServerHello";
338 case MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST: return "HelloVerifyRequest";
339 case MBEDTLS_SSL_HS_NEW_SESSION_TICKET: return "NewSessionTicket";
340 case MBEDTLS_SSL_HS_CERTIFICATE: return "Certificate";
341 case MBEDTLS_SSL_HS_SERVER_KEY_EXCHANGE: return "ServerKeyExchange";
342 case MBEDTLS_SSL_HS_CERTIFICATE_REQUEST: return "CertificateRequest";
343 case MBEDTLS_SSL_HS_SERVER_HELLO_DONE: return "ServerHelloDone";
344 case MBEDTLS_SSL_HS_CERTIFICATE_VERIFY: return "CertificateVerify";
345 case MBEDTLS_SSL_HS_CLIENT_KEY_EXCHANGE: return "ClientKeyExchange";
346 case MBEDTLS_SSL_HS_FINISHED: return "Finished";
347 default: return "Unknown handshake";
348 }
349 }
350
351 #if defined(MBEDTLS_TIMING_C)
352 /* Return elapsed time in milliseconds since the first call */
elapsed_time(void)353 static unsigned elapsed_time(void)
354 {
355 static int initialized = 0;
356 static struct mbedtls_timing_hr_time hires;
357
358 if (initialized == 0) {
359 (void) mbedtls_timing_get_timer(&hires, 1);
360 initialized = 1;
361 return 0;
362 }
363
364 return mbedtls_timing_get_timer(&hires, 0);
365 }
366
367 typedef struct {
368 mbedtls_net_context *ctx;
369
370 const char *description;
371
372 unsigned packet_lifetime;
373 unsigned num_datagrams;
374
375 unsigned char data[MAX_MSG_SIZE];
376 size_t len;
377
378 } ctx_buffer;
379
380 static ctx_buffer outbuf[2];
381
ctx_buffer_flush(ctx_buffer * buf)382 static int ctx_buffer_flush(ctx_buffer *buf)
383 {
384 int ret;
385
386 mbedtls_printf(" %05u flush %s: %u bytes, %u datagrams, last %u ms\n",
387 elapsed_time(), buf->description,
388 (unsigned) buf->len, buf->num_datagrams,
389 elapsed_time() - buf->packet_lifetime);
390
391 ret = mbedtls_net_send(buf->ctx, buf->data, buf->len);
392
393 buf->len = 0;
394 buf->num_datagrams = 0;
395
396 return ret;
397 }
398
ctx_buffer_time_remaining(ctx_buffer * buf)399 static unsigned ctx_buffer_time_remaining(ctx_buffer *buf)
400 {
401 unsigned const cur_time = elapsed_time();
402
403 if (buf->num_datagrams == 0) {
404 return (unsigned) -1;
405 }
406
407 if (cur_time - buf->packet_lifetime >= opt.pack) {
408 return 0;
409 }
410
411 return opt.pack - (cur_time - buf->packet_lifetime);
412 }
413
ctx_buffer_append(ctx_buffer * buf,const unsigned char * data,size_t len)414 static int ctx_buffer_append(ctx_buffer *buf,
415 const unsigned char *data,
416 size_t len)
417 {
418 int ret;
419
420 if (len > (size_t) INT_MAX) {
421 return -1;
422 }
423
424 if (len > sizeof(buf->data)) {
425 mbedtls_printf(" ! buffer size %u too large (max %u)\n",
426 (unsigned) len, (unsigned) sizeof(buf->data));
427 return -1;
428 }
429
430 if (sizeof(buf->data) - buf->len < len) {
431 if ((ret = ctx_buffer_flush(buf)) <= 0) {
432 mbedtls_printf("ctx_buffer_flush failed with -%#04x", (unsigned int) -ret);
433 return ret;
434 }
435 }
436
437 memcpy(buf->data + buf->len, data, len);
438
439 buf->len += len;
440 if (++buf->num_datagrams == 1) {
441 buf->packet_lifetime = elapsed_time();
442 }
443
444 return (int) len;
445 }
446 #endif /* MBEDTLS_TIMING_C */
447
dispatch_data(mbedtls_net_context * ctx,const unsigned char * data,size_t len)448 static int dispatch_data(mbedtls_net_context *ctx,
449 const unsigned char *data,
450 size_t len)
451 {
452 int ret;
453 #if defined(MBEDTLS_TIMING_C)
454 ctx_buffer *buf = NULL;
455 if (opt.pack > 0) {
456 if (outbuf[0].ctx == ctx) {
457 buf = &outbuf[0];
458 } else if (outbuf[1].ctx == ctx) {
459 buf = &outbuf[1];
460 }
461
462 if (buf == NULL) {
463 return -1;
464 }
465
466 return ctx_buffer_append(buf, data, len);
467 }
468 #endif /* MBEDTLS_TIMING_C */
469
470 ret = mbedtls_net_send(ctx, data, len);
471 if (ret < 0) {
472 mbedtls_printf("net_send returned -%#04x\n", (unsigned int) -ret);
473 }
474 return ret;
475 }
476
477 typedef struct {
478 mbedtls_net_context *dst;
479 const char *way;
480 const char *type;
481 unsigned len;
482 unsigned char buf[MAX_MSG_SIZE];
483 } packet;
484
485 /* Print packet. Outgoing packets come with a reason (forward, dupl, etc.) */
print_packet(const packet * p,const char * why)486 void print_packet(const packet *p, const char *why)
487 {
488 #if defined(MBEDTLS_TIMING_C)
489 if (why == NULL) {
490 mbedtls_printf(" %05u dispatch %s %s (%u bytes)\n",
491 elapsed_time(), p->way, p->type, p->len);
492 } else {
493 mbedtls_printf(" %05u dispatch %s %s (%u bytes): %s\n",
494 elapsed_time(), p->way, p->type, p->len, why);
495 }
496 #else
497 if (why == NULL) {
498 mbedtls_printf(" dispatch %s %s (%u bytes)\n",
499 p->way, p->type, p->len);
500 } else {
501 mbedtls_printf(" dispatch %s %s (%u bytes): %s\n",
502 p->way, p->type, p->len, why);
503 }
504 #endif
505
506 fflush(stdout);
507 }
508
509 /*
510 * In order to test the server's behaviour when receiving a ClientHello after
511 * the connection is established (this could be a hard reset from the client,
512 * but the server must not drop the existing connection before establishing
513 * client reachability, see RFC 6347 Section 4.2.8), we memorize the first
514 * ClientHello we see (which can't have a cookie), then replay it after the
515 * first ApplicationData record - then we're done.
516 *
517 * This is controlled by the inject_clihlo option.
518 *
519 * We want an explicit state and a place to store the packet.
520 */
521 typedef enum {
522 ICH_INIT, /* haven't seen the first ClientHello yet */
523 ICH_CACHED, /* cached the initial ClientHello */
524 ICH_INJECTED, /* ClientHello already injected, done */
525 } inject_clihlo_state_t;
526
527 static inject_clihlo_state_t inject_clihlo_state;
528 static packet initial_clihlo;
529
send_packet(const packet * p,const char * why)530 int send_packet(const packet *p, const char *why)
531 {
532 int ret;
533 mbedtls_net_context *dst = p->dst;
534
535 /* save initial ClientHello? */
536 if (opt.inject_clihlo != 0 &&
537 inject_clihlo_state == ICH_INIT &&
538 strcmp(p->type, "ClientHello") == 0) {
539 memcpy(&initial_clihlo, p, sizeof(packet));
540 inject_clihlo_state = ICH_CACHED;
541 }
542
543 /* insert corrupted CID record? */
544 if (opt.bad_cid != 0 &&
545 strcmp(p->type, "CID") == 0 &&
546 (rand() % opt.bad_cid) == 0) {
547 unsigned char buf[MAX_MSG_SIZE];
548 memcpy(buf, p->buf, p->len);
549
550 /* The CID resides at offset 11 in the DTLS record header. */
551 buf[11] ^= 1;
552 print_packet(p, "modified CID");
553
554 if ((ret = dispatch_data(dst, buf, p->len)) <= 0) {
555 mbedtls_printf(" ! dispatch returned %d\n", ret);
556 return ret;
557 }
558 }
559
560 /* insert corrupted ApplicationData record? */
561 if (opt.bad_ad &&
562 strcmp(p->type, "ApplicationData") == 0) {
563 unsigned char buf[MAX_MSG_SIZE];
564 memcpy(buf, p->buf, p->len);
565
566 if (p->len <= 13) {
567 mbedtls_printf(" ! can't corrupt empty AD record");
568 } else {
569 ++buf[13];
570 print_packet(p, "corrupted");
571 }
572
573 if ((ret = dispatch_data(dst, buf, p->len)) <= 0) {
574 mbedtls_printf(" ! dispatch returned %d\n", ret);
575 return ret;
576 }
577 }
578
579 print_packet(p, why);
580 if ((ret = dispatch_data(dst, p->buf, p->len)) <= 0) {
581 mbedtls_printf(" ! dispatch returned %d\n", ret);
582 return ret;
583 }
584
585 /* Don't duplicate Application Data, only handshake covered */
586 if (opt.duplicate != 0 &&
587 strcmp(p->type, "ApplicationData") != 0 &&
588 rand() % opt.duplicate == 0) {
589 print_packet(p, "duplicated");
590
591 if ((ret = dispatch_data(dst, p->buf, p->len)) <= 0) {
592 mbedtls_printf(" ! dispatch returned %d\n", ret);
593 return ret;
594 }
595 }
596
597 /* Inject ClientHello after first ApplicationData */
598 if (opt.inject_clihlo != 0 &&
599 inject_clihlo_state == ICH_CACHED &&
600 strcmp(p->type, "ApplicationData") == 0) {
601 print_packet(&initial_clihlo, "injected");
602
603 if ((ret = dispatch_data(dst, initial_clihlo.buf,
604 initial_clihlo.len)) <= 0) {
605 mbedtls_printf(" ! dispatch returned %d\n", ret);
606 return ret;
607 }
608
609 inject_clihlo_state = ICH_INJECTED;
610 }
611
612 return 0;
613 }
614
615 #define MAX_DELAYED_MSG 5
616 static size_t prev_len;
617 static packet prev[MAX_DELAYED_MSG];
618
clear_pending(void)619 void clear_pending(void)
620 {
621 memset(&prev, 0, sizeof(prev));
622 prev_len = 0;
623 }
624
delay_packet(packet * delay)625 void delay_packet(packet *delay)
626 {
627 if (prev_len == MAX_DELAYED_MSG) {
628 return;
629 }
630
631 memcpy(&prev[prev_len++], delay, sizeof(packet));
632 }
633
send_delayed(void)634 int send_delayed(void)
635 {
636 uint8_t offset;
637 int ret;
638 for (offset = 0; offset < prev_len; offset++) {
639 ret = send_packet(&prev[offset], "delayed");
640 if (ret != 0) {
641 return ret;
642 }
643 }
644
645 clear_pending();
646 return 0;
647 }
648
649 /*
650 * Avoid dropping or delaying a packet that was already dropped or delayed
651 * ("held") twice: this only results in uninteresting timeouts. We can't rely
652 * on type to identify packets, since during renegotiation they're all
653 * encrypted. So, rely on size mod 2048 (which is usually just size).
654 *
655 * We only hold packets at the level of entire datagrams, not at the level
656 * of records. In particular, if the peer changes the way it packs multiple
657 * records into a single datagram, we don't necessarily count the number of
658 * times a record has been held correctly. However, the only known reason
659 * why a peer would change datagram packing is disabling the latter on
660 * retransmission, in which case we'd hold involved records at most
661 * HOLD_MAX + 1 times.
662 */
663 static unsigned char held[2048] = { 0 };
664 #define HOLD_MAX 2
665
handle_message(const char * way,mbedtls_net_context * dst,mbedtls_net_context * src)666 int handle_message(const char *way,
667 mbedtls_net_context *dst,
668 mbedtls_net_context *src)
669 {
670 int ret;
671 packet cur;
672 size_t id;
673
674 uint8_t delay_idx;
675 char **delay_list;
676 uint8_t delay_list_len;
677
678 /* receive packet */
679 if ((ret = mbedtls_net_recv(src, cur.buf, sizeof(cur.buf))) <= 0) {
680 mbedtls_printf(" ! mbedtls_net_recv returned %d\n", ret);
681 return ret;
682 }
683
684 cur.len = ret;
685 cur.type = msg_type(cur.buf, cur.len);
686 cur.way = way;
687 cur.dst = dst;
688 print_packet(&cur, NULL);
689
690 id = cur.len % sizeof(held);
691
692 if (strcmp(way, "S <- C") == 0) {
693 delay_list = opt.delay_cli;
694 delay_list_len = opt.delay_cli_cnt;
695 } else {
696 delay_list = opt.delay_srv;
697 delay_list_len = opt.delay_srv_cnt;
698 }
699
700 /* Check if message type is in the list of messages
701 * that should be delayed */
702 for (delay_idx = 0; delay_idx < delay_list_len; delay_idx++) {
703 if (delay_list[delay_idx] == NULL) {
704 continue;
705 }
706
707 if (strcmp(delay_list[delay_idx], cur.type) == 0) {
708 /* Delay message */
709 delay_packet(&cur);
710
711 /* Remove entry from list */
712 mbedtls_free(delay_list[delay_idx]);
713 delay_list[delay_idx] = NULL;
714
715 return 0;
716 }
717 }
718
719 /* do we want to drop, delay, or forward it? */
720 if ((opt.mtu != 0 &&
721 cur.len > (unsigned) opt.mtu) ||
722 (opt.drop != 0 &&
723 strcmp(cur.type, "CID") != 0 &&
724 strcmp(cur.type, "ApplicationData") != 0 &&
725 !(opt.protect_hvr &&
726 strcmp(cur.type, "HelloVerifyRequest") == 0) &&
727 cur.len != (size_t) opt.protect_len &&
728 held[id] < HOLD_MAX &&
729 rand() % opt.drop == 0)) {
730 ++held[id];
731 } else if ((opt.delay_ccs == 1 &&
732 strcmp(cur.type, "ChangeCipherSpec") == 0) ||
733 (opt.delay != 0 &&
734 strcmp(cur.type, "CID") != 0 &&
735 strcmp(cur.type, "ApplicationData") != 0 &&
736 !(opt.protect_hvr &&
737 strcmp(cur.type, "HelloVerifyRequest") == 0) &&
738 cur.len != (size_t) opt.protect_len &&
739 held[id] < HOLD_MAX &&
740 rand() % opt.delay == 0)) {
741 ++held[id];
742 delay_packet(&cur);
743 } else {
744 /* forward and possibly duplicate */
745 if ((ret = send_packet(&cur, "forwarded")) != 0) {
746 return ret;
747 }
748
749 /* send previously delayed messages if any */
750 ret = send_delayed();
751 if (ret != 0) {
752 return ret;
753 }
754 }
755
756 return 0;
757 }
758
main(int argc,char * argv[])759 int main(int argc, char *argv[])
760 {
761 int ret = 1;
762 int exit_code = MBEDTLS_EXIT_FAILURE;
763 uint8_t delay_idx;
764
765 mbedtls_net_context listen_fd, client_fd, server_fd;
766
767 #if defined(MBEDTLS_TIMING_C)
768 struct timeval tm;
769 #endif
770
771 struct timeval *tm_ptr = NULL;
772
773 int nb_fds;
774 fd_set read_fds;
775
776 mbedtls_net_init(&listen_fd);
777 mbedtls_net_init(&client_fd);
778 mbedtls_net_init(&server_fd);
779
780 get_options(argc, argv);
781
782 /*
783 * Decisions to drop/delay/duplicate packets are pseudo-random: dropping
784 * exactly 1 in N packets would lead to problems when a flight has exactly
785 * N packets: the same packet would be dropped on every resend.
786 *
787 * In order to be able to reproduce problems reliably, the seed may be
788 * specified explicitly.
789 */
790 if (opt.seed == 0) {
791 #if defined(MBEDTLS_HAVE_TIME)
792 opt.seed = (unsigned int) mbedtls_time(NULL);
793 #else
794 opt.seed = 1;
795 #endif /* MBEDTLS_HAVE_TIME */
796 mbedtls_printf(" . Pseudo-random seed: %u\n", opt.seed);
797 }
798
799 srand(opt.seed);
800
801 /*
802 * 0. "Connect" to the server
803 */
804 mbedtls_printf(" . Connect to server on UDP/%s/%s ...",
805 opt.server_addr, opt.server_port);
806 fflush(stdout);
807
808 if ((ret = mbedtls_net_connect(&server_fd, opt.server_addr, opt.server_port,
809 MBEDTLS_NET_PROTO_UDP)) != 0) {
810 mbedtls_printf(" failed\n ! mbedtls_net_connect returned %d\n\n", ret);
811 goto exit;
812 }
813
814 mbedtls_printf(" ok\n");
815
816 /*
817 * 1. Setup the "listening" UDP socket
818 */
819 mbedtls_printf(" . Bind on UDP/%s/%s ...",
820 opt.listen_addr, opt.listen_port);
821 fflush(stdout);
822
823 if ((ret = mbedtls_net_bind(&listen_fd, opt.listen_addr, opt.listen_port,
824 MBEDTLS_NET_PROTO_UDP)) != 0) {
825 mbedtls_printf(" failed\n ! mbedtls_net_bind returned %d\n\n", ret);
826 goto exit;
827 }
828
829 mbedtls_printf(" ok\n");
830
831 /*
832 * 2. Wait until a client connects
833 */
834 accept:
835 mbedtls_net_free(&client_fd);
836
837 mbedtls_printf(" . Waiting for a remote connection ...");
838 fflush(stdout);
839
840 if ((ret = mbedtls_net_accept(&listen_fd, &client_fd,
841 NULL, 0, NULL)) != 0) {
842 mbedtls_printf(" failed\n ! mbedtls_net_accept returned %d\n\n", ret);
843 goto exit;
844 }
845
846 mbedtls_printf(" ok\n");
847
848 /*
849 * 3. Forward packets forever (kill the process to terminate it)
850 */
851 clear_pending();
852 memset(held, 0, sizeof(held));
853
854 nb_fds = client_fd.fd;
855 if (nb_fds < server_fd.fd) {
856 nb_fds = server_fd.fd;
857 }
858 if (nb_fds < listen_fd.fd) {
859 nb_fds = listen_fd.fd;
860 }
861 ++nb_fds;
862
863 #if defined(MBEDTLS_TIMING_C)
864 if (opt.pack > 0) {
865 outbuf[0].ctx = &server_fd;
866 outbuf[0].description = "S <- C";
867 outbuf[0].num_datagrams = 0;
868 outbuf[0].len = 0;
869
870 outbuf[1].ctx = &client_fd;
871 outbuf[1].description = "S -> C";
872 outbuf[1].num_datagrams = 0;
873 outbuf[1].len = 0;
874 }
875 #endif /* MBEDTLS_TIMING_C */
876
877 while (1) {
878 #if defined(MBEDTLS_TIMING_C)
879 if (opt.pack > 0) {
880 unsigned max_wait_server, max_wait_client, max_wait;
881 max_wait_server = ctx_buffer_time_remaining(&outbuf[0]);
882 max_wait_client = ctx_buffer_time_remaining(&outbuf[1]);
883
884 max_wait = (unsigned) -1;
885
886 if (max_wait_server == 0) {
887 ctx_buffer_flush(&outbuf[0]);
888 } else {
889 max_wait = max_wait_server;
890 }
891
892 if (max_wait_client == 0) {
893 ctx_buffer_flush(&outbuf[1]);
894 } else {
895 if (max_wait_client < max_wait) {
896 max_wait = max_wait_client;
897 }
898 }
899
900 if (max_wait != (unsigned) -1) {
901 tm.tv_sec = max_wait / 1000;
902 tm.tv_usec = (max_wait % 1000) * 1000;
903
904 tm_ptr = &tm;
905 } else {
906 tm_ptr = NULL;
907 }
908 }
909 #endif /* MBEDTLS_TIMING_C */
910
911 FD_ZERO(&read_fds);
912 FD_SET(server_fd.fd, &read_fds);
913 FD_SET(client_fd.fd, &read_fds);
914 FD_SET(listen_fd.fd, &read_fds);
915
916 if ((ret = select(nb_fds, &read_fds, NULL, NULL, tm_ptr)) < 0) {
917 perror("select");
918 goto exit;
919 }
920
921 if (FD_ISSET(listen_fd.fd, &read_fds)) {
922 goto accept;
923 }
924
925 if (FD_ISSET(client_fd.fd, &read_fds)) {
926 if ((ret = handle_message("S <- C",
927 &server_fd, &client_fd)) != 0) {
928 goto accept;
929 }
930 }
931
932 if (FD_ISSET(server_fd.fd, &read_fds)) {
933 if ((ret = handle_message("S -> C",
934 &client_fd, &server_fd)) != 0) {
935 goto accept;
936 }
937 }
938
939 }
940
941 exit_code = MBEDTLS_EXIT_SUCCESS;
942
943 exit:
944
945 #ifdef MBEDTLS_ERROR_C
946 if (exit_code != MBEDTLS_EXIT_SUCCESS) {
947 char error_buf[100];
948 mbedtls_strerror(ret, error_buf, 100);
949 mbedtls_printf("Last error was: -0x%04X - %s\n\n", (unsigned int) -ret, error_buf);
950 fflush(stdout);
951 }
952 #endif
953
954 for (delay_idx = 0; delay_idx < MAX_DELAYED_HS; delay_idx++) {
955 mbedtls_free(opt.delay_cli[delay_idx]);
956 mbedtls_free(opt.delay_srv[delay_idx]);
957 }
958
959 mbedtls_net_free(&client_fd);
960 mbedtls_net_free(&server_fd);
961 mbedtls_net_free(&listen_fd);
962
963 mbedtls_exit(exit_code);
964 }
965
966 #endif /* MBEDTLS_NET_C */
967
