1 /* $OpenBSD: tls13_internal.h,v 1.101 2022/07/24 14:28:16 jsing Exp $ */
2 /*
3  * Copyright (c) 2018 Bob Beck <beck@openbsd.org>
4  * Copyright (c) 2018 Theo Buehler <tb@openbsd.org>
5  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
6  *
7  * Permission to use, copy, modify, and/or distribute this software for any
8  * purpose with or without fee is hereby granted, provided that the above
9  * copyright notice and this permission notice appear in all copies.
10  *
11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
14  * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
16  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
17  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18  */
19 
20 #ifndef HEADER_TLS13_INTERNAL_H
21 #define HEADER_TLS13_INTERNAL_H
22 
23 #include <openssl/evp.h>
24 #include <openssl/ssl.h>
25 
26 #include "bytestring.h"
27 #include "tls_internal.h"
28 
29 __BEGIN_HIDDEN_DECLS
30 
31 #define TLS13_HS_CLIENT			1
32 #define TLS13_HS_SERVER			2
33 
34 #define TLS13_IO_SUCCESS		 1
35 #define TLS13_IO_EOF			 0
36 #define TLS13_IO_FAILURE		-1
37 #define TLS13_IO_ALERT			-2
38 #define TLS13_IO_WANT_POLLIN		-3
39 #define TLS13_IO_WANT_POLLOUT		-4
40 #define TLS13_IO_WANT_RETRY		-5 /* Retry the previous call immediately. */
41 #define TLS13_IO_USE_LEGACY		-6
42 #define TLS13_IO_RECORD_VERSION		-7
43 #define TLS13_IO_RECORD_OVERFLOW	-8
44 
45 #define TLS13_ERR_VERIFY_FAILED		16
46 #define TLS13_ERR_HRR_FAILED		17
47 #define TLS13_ERR_TRAILING_DATA		18
48 #define TLS13_ERR_NO_SHARED_CIPHER	19
49 #define TLS13_ERR_NO_CERTIFICATE	20
50 #define TLS13_ERR_NO_PEER_CERTIFICATE	21
51 
52 #define TLS13_ALERT_LEVEL_WARNING			1
53 #define TLS13_ALERT_LEVEL_FATAL				2
54 
55 #define TLS13_ALERT_CLOSE_NOTIFY			0
56 #define TLS13_ALERT_UNEXPECTED_MESSAGE			10
57 #define TLS13_ALERT_BAD_RECORD_MAC			20
58 #define TLS13_ALERT_RECORD_OVERFLOW			22
59 #define TLS13_ALERT_HANDSHAKE_FAILURE			40
60 #define TLS13_ALERT_BAD_CERTIFICATE			42
61 #define TLS13_ALERT_UNSUPPORTED_CERTIFICATE		43
62 #define TLS13_ALERT_CERTIFICATE_REVOKED			44
63 #define TLS13_ALERT_CERTIFICATE_EXPIRED			45
64 #define TLS13_ALERT_CERTIFICATE_UNKNOWN			46
65 #define TLS13_ALERT_ILLEGAL_PARAMETER			47
66 #define TLS13_ALERT_UNKNOWN_CA				48
67 #define TLS13_ALERT_ACCESS_DENIED			49
68 #define TLS13_ALERT_DECODE_ERROR			50
69 #define TLS13_ALERT_DECRYPT_ERROR			51
70 #define TLS13_ALERT_PROTOCOL_VERSION			70
71 #define TLS13_ALERT_INSUFFICIENT_SECURITY		71
72 #define TLS13_ALERT_INTERNAL_ERROR			80
73 #define TLS13_ALERT_INAPPROPRIATE_FALLBACK		86
74 #define TLS13_ALERT_USER_CANCELED			90
75 #define TLS13_ALERT_MISSING_EXTENSION			109
76 #define TLS13_ALERT_UNSUPPORTED_EXTENSION		110
77 #define TLS13_ALERT_UNRECOGNIZED_NAME			112
78 #define TLS13_ALERT_BAD_CERTIFICATE_STATUS_RESPONSE	113
79 #define TLS13_ALERT_UNKNOWN_PSK_IDENTITY		115
80 #define TLS13_ALERT_CERTIFICATE_REQUIRED		116
81 #define TLS13_ALERT_NO_APPLICATION_PROTOCOL		120
82 
83 #define TLS13_INFO_HANDSHAKE_STARTED			SSL_CB_HANDSHAKE_START
84 #define TLS13_INFO_HANDSHAKE_COMPLETED			SSL_CB_HANDSHAKE_DONE
85 #define TLS13_INFO_ACCEPT_LOOP				SSL_CB_ACCEPT_LOOP
86 #define TLS13_INFO_CONNECT_LOOP				SSL_CB_CONNECT_LOOP
87 #define TLS13_INFO_ACCEPT_EXIT				SSL_CB_ACCEPT_EXIT
88 #define TLS13_INFO_CONNECT_EXIT				SSL_CB_CONNECT_EXIT
89 
90 typedef void (*tls13_alert_cb)(uint8_t _alert_desc, void *_cb_arg);
91 typedef ssize_t (*tls13_phh_recv_cb)(void *_cb_arg);
92 typedef void (*tls13_phh_sent_cb)(void *_cb_arg);
93 typedef void (*tls13_handshake_message_cb)(void *_cb_arg);
94 typedef void (*tls13_info_cb)(void *_cb_arg, int _state, int _ret);
95 typedef int (*tls13_ocsp_status_cb)(void *_cb_arg);
96 
97 /*
98  * PSK support.
99  */
100 
101 /*
102  * Known PskKeyExchangeMode values.
103  * https://www.iana.org/assignments/tls-parameters/#tls-pskkeyexchangemode
104  */
105 #define TLS13_PSK_KE					0
106 #define TLS13_PSK_DHE_KE				1
107 
108 /*
109  * Secrets.
110  */
111 struct tls13_secret {
112 	uint8_t *data;
113 	size_t len;
114 };
115 
116 /* RFC 8446 Section 7.1  Page 92 */
117 struct tls13_secrets {
118 	const EVP_MD *digest;
119 	int resumption;
120 	int init_done;
121 	int early_done;
122 	int handshake_done;
123 	int schedule_done;
124 	int insecure; /* Set by tests */
125 	struct tls13_secret zeros;
126 	struct tls13_secret empty_hash;
127 	struct tls13_secret extracted_early;
128 	struct tls13_secret binder_key;
129 	struct tls13_secret client_early_traffic;
130 	struct tls13_secret early_exporter_master;
131 	struct tls13_secret derived_early;
132 	struct tls13_secret extracted_handshake;
133 	struct tls13_secret client_handshake_traffic;
134 	struct tls13_secret server_handshake_traffic;
135 	struct tls13_secret derived_handshake;
136 	struct tls13_secret extracted_master;
137 	struct tls13_secret client_application_traffic;
138 	struct tls13_secret server_application_traffic;
139 	struct tls13_secret exporter_master;
140 	struct tls13_secret resumption_master;
141 };
142 
143 int tls13_secret_init(struct tls13_secret *secret, size_t len);
144 void tls13_secret_cleanup(struct tls13_secret *secret);
145 struct tls13_secrets *tls13_secrets_create(const EVP_MD *digest,
146     int resumption);
147 void tls13_secrets_destroy(struct tls13_secrets *secrets);
148 
149 int tls13_hkdf_expand_label(struct tls13_secret *out, const EVP_MD *digest,
150     const struct tls13_secret *secret, const char *label,
151     const struct tls13_secret *context);
152 int tls13_hkdf_expand_label_with_length(struct tls13_secret *out,
153     const EVP_MD *digest, const struct tls13_secret *secret,
154     const uint8_t *label, size_t label_len, const struct tls13_secret *context);
155 
156 int tls13_derive_secret(struct tls13_secret *out, const EVP_MD *digest,
157     const struct tls13_secret *secret, const char *label,
158     const struct tls13_secret *context);
159 int tls13_derive_secret_with_label_length(struct tls13_secret *out,
160     const EVP_MD *digest, const struct tls13_secret *secret,
161     const uint8_t *label, size_t label_len, const struct tls13_secret *context);
162 
163 int tls13_derive_early_secrets(struct tls13_secrets *secrets, uint8_t *psk,
164     size_t psk_len, const struct tls13_secret *context);
165 int tls13_derive_handshake_secrets(struct tls13_secrets *secrets,
166     const uint8_t *ecdhe, size_t ecdhe_len, const struct tls13_secret *context);
167 int tls13_derive_application_secrets(struct tls13_secrets *secrets,
168     const struct tls13_secret *context);
169 int tls13_update_client_traffic_secret(struct tls13_secrets *secrets);
170 int tls13_update_server_traffic_secret(struct tls13_secrets *secrets);
171 
172 /*
173  * Record Layer.
174  */
175 struct tls13_record_layer;
176 
177 struct tls13_record_layer_callbacks {
178 	/* Wire callbacks. */
179 	tls_read_cb wire_read;
180 	tls_write_cb wire_write;
181 	tls_flush_cb wire_flush;
182 
183 	/* Interceptors. */
184 	tls_handshake_read_cb handshake_read;
185 	tls_handshake_write_cb handshake_write;
186 	tls_traffic_key_cb set_read_traffic_key;
187 	tls_traffic_key_cb set_write_traffic_key;
188 	tls_alert_send_cb alert_send;
189 
190 	/* Notification callbacks. */
191 	tls13_alert_cb alert_recv;
192 	tls13_alert_cb alert_sent;
193 	tls13_phh_recv_cb phh_recv;
194 	tls13_phh_sent_cb phh_sent;
195 };
196 
197 struct tls13_record_layer *tls13_record_layer_new(
198     const struct tls13_record_layer_callbacks *callbacks, void *cb_arg);
199 void tls13_record_layer_free(struct tls13_record_layer *rl);
200 void tls13_record_layer_set_callbacks(struct tls13_record_layer *rl,
201     const struct tls13_record_layer_callbacks *callbacks, void *cb_arg);
202 void tls13_record_layer_allow_ccs(struct tls13_record_layer *rl, int allow);
203 void tls13_record_layer_allow_legacy_alerts(struct tls13_record_layer *rl, int allow);
204 void tls13_record_layer_rcontent(struct tls13_record_layer *rl, CBS *cbs);
205 void tls13_record_layer_set_aead(struct tls13_record_layer *rl,
206     const EVP_AEAD *aead);
207 void tls13_record_layer_set_hash(struct tls13_record_layer *rl,
208     const EVP_MD *hash);
209 void tls13_record_layer_set_legacy_version(struct tls13_record_layer *rl,
210     uint16_t version);
211 void tls13_record_layer_set_retry_after_phh(struct tls13_record_layer *rl, int retry);
212 void tls13_record_layer_handshake_completed(struct tls13_record_layer *rl);
213 int tls13_record_layer_set_read_traffic_key(struct tls13_record_layer *rl,
214     struct tls13_secret *read_key, enum ssl_encryption_level_t read_level);
215 int tls13_record_layer_set_write_traffic_key(struct tls13_record_layer *rl,
216     struct tls13_secret *write_key, enum ssl_encryption_level_t write_level);
217 ssize_t tls13_record_layer_send_pending(struct tls13_record_layer *rl);
218 ssize_t tls13_record_layer_phh(struct tls13_record_layer *rl, CBS *cbs);
219 ssize_t tls13_record_layer_flush(struct tls13_record_layer *rl);
220 
221 ssize_t tls13_read_handshake_data(struct tls13_record_layer *rl, uint8_t *buf, size_t n);
222 ssize_t tls13_write_handshake_data(struct tls13_record_layer *rl, const uint8_t *buf,
223     size_t n);
224 ssize_t tls13_pending_application_data(struct tls13_record_layer *rl);
225 ssize_t tls13_peek_application_data(struct tls13_record_layer *rl, uint8_t *buf, size_t n);
226 ssize_t tls13_read_application_data(struct tls13_record_layer *rl, uint8_t *buf, size_t n);
227 ssize_t tls13_write_application_data(struct tls13_record_layer *rl, const uint8_t *buf,
228     size_t n);
229 
230 ssize_t tls13_send_alert(struct tls13_record_layer *rl, uint8_t alert_desc);
231 ssize_t tls13_send_dummy_ccs(struct tls13_record_layer *rl);
232 
233 /*
234  * Handshake Messages.
235  */
236 struct tls13_handshake_msg;
237 
238 struct tls13_handshake_msg *tls13_handshake_msg_new(void);
239 void tls13_handshake_msg_free(struct tls13_handshake_msg *msg);
240 void tls13_handshake_msg_data(struct tls13_handshake_msg *msg, CBS *cbs);
241 uint8_t tls13_handshake_msg_type(struct tls13_handshake_msg *msg);
242 int tls13_handshake_msg_content(struct tls13_handshake_msg *msg, CBS *cbs);
243 int tls13_handshake_msg_start(struct tls13_handshake_msg *msg, CBB *body,
244     uint8_t msg_type);
245 int tls13_handshake_msg_finish(struct tls13_handshake_msg *msg);
246 int tls13_handshake_msg_recv(struct tls13_handshake_msg *msg,
247     struct tls13_record_layer *rl);
248 int tls13_handshake_msg_send(struct tls13_handshake_msg *msg,
249     struct tls13_record_layer *rl);
250 
251 struct tls13_handshake_stage {
252 	uint8_t	hs_type;
253 	uint8_t	message_number;
254 };
255 
256 struct ssl_handshake_tls13_st;
257 
258 struct tls13_error {
259 	int code;
260 	int subcode;
261 	int errnum;
262 	const char *file;
263 	int line;
264 	char *msg;
265 };
266 
267 struct tls13_ctx {
268 	struct tls13_error error;
269 
270 	SSL *ssl;
271 	struct ssl_handshake_st *hs;
272 	uint8_t	mode;
273 	struct tls13_handshake_stage handshake_stage;
274 	int handshake_started;
275 	int handshake_completed;
276 	int need_flush;
277 	int middlebox_compat;
278 	int send_dummy_ccs;
279 	int send_dummy_ccs_after;
280 
281 	int close_notify_sent;
282 	int close_notify_recv;
283 
284 	const EVP_AEAD *aead;
285 	const EVP_MD *hash;
286 
287 	struct tls13_record_layer *rl;
288 	struct tls13_handshake_msg *hs_msg;
289 	uint8_t key_update_request;
290 	uint8_t alert;
291 	int phh_count;
292 	time_t phh_last_seen;
293 
294 	tls13_handshake_message_cb handshake_message_sent_cb;
295 	tls13_handshake_message_cb handshake_message_recv_cb;
296 	tls13_info_cb info_cb;
297 	tls13_ocsp_status_cb ocsp_status_recv_cb;
298 };
299 #ifndef TLS13_PHH_LIMIT_TIME
300 #define TLS13_PHH_LIMIT_TIME 3600
301 #endif
302 #ifndef TLS13_PHH_LIMIT
303 #define TLS13_PHH_LIMIT 100
304 #endif
305 
306 struct tls13_ctx *tls13_ctx_new(int mode, SSL *ssl);
307 void tls13_ctx_free(struct tls13_ctx *ctx);
308 
309 const EVP_AEAD *tls13_cipher_aead(const SSL_CIPHER *cipher);
310 const EVP_MD *tls13_cipher_hash(const SSL_CIPHER *cipher);
311 
312 void tls13_alert_received_cb(uint8_t alert_desc, void *arg);
313 void tls13_alert_sent_cb(uint8_t alert_desc, void *arg);
314 ssize_t tls13_phh_received_cb(void *cb_arg);
315 void tls13_phh_done_cb(void *cb_arg);
316 
317 int tls13_quic_init(struct tls13_ctx *ctx);
318 
319 /*
320  * Legacy interfaces.
321  */
322 int tls13_use_legacy_client(struct tls13_ctx *ctx);
323 int tls13_use_legacy_server(struct tls13_ctx *ctx);
324 int tls13_legacy_accept(SSL *ssl);
325 int tls13_legacy_connect(SSL *ssl);
326 int tls13_legacy_return_code(SSL *ssl, ssize_t ret);
327 ssize_t tls13_legacy_wire_read_cb(void *buf, size_t n, void *arg);
328 ssize_t tls13_legacy_wire_write_cb(const void *buf, size_t n, void *arg);
329 ssize_t tls13_legacy_wire_flush_cb(void *arg);
330 int tls13_legacy_pending(const SSL *ssl);
331 int tls13_legacy_read_bytes(SSL *ssl, int type, unsigned char *buf, int len,
332     int peek);
333 int tls13_legacy_write_bytes(SSL *ssl, int type, const void *buf, int len);
334 int tls13_legacy_shutdown(SSL *ssl);
335 int tls13_legacy_servername_process(struct tls13_ctx *ctx, uint8_t *alert);
336 
337 /*
338  * Message Types - RFC 8446, Section B.3.
339  *
340  * Values listed as "_RESERVED" were used in previous versions of TLS and are
341  * listed here for completeness.  TLS 1.3 implementations MUST NOT send them but
342  * might receive them from older TLS implementations.
343  */
344 #define	TLS13_MT_HELLO_REQUEST_RESERVED		0
345 #define	TLS13_MT_CLIENT_HELLO			1
346 #define	TLS13_MT_SERVER_HELLO			2
347 #define	TLS13_MT_HELLO_VERIFY_REQUEST_RESERVED	3
348 #define	TLS13_MT_NEW_SESSION_TICKET		4
349 #define	TLS13_MT_END_OF_EARLY_DATA		5
350 #define	TLS13_MT_HELLO_RETRY_REQUEST_RESERVED	6
351 #define	TLS13_MT_ENCRYPTED_EXTENSIONS		8
352 #define	TLS13_MT_CERTIFICATE			11
353 #define	TLS13_MT_SERVER_KEY_EXCHANGE_RESERVED	12
354 #define	TLS13_MT_CERTIFICATE_REQUEST		13
355 #define	TLS13_MT_SERVER_HELLO_DONE_RESERVED	14
356 #define	TLS13_MT_CERTIFICATE_VERIFY		15
357 #define	TLS13_MT_CLIENT_KEY_EXCHANGE_RESERVED	16
358 #define	TLS13_MT_FINISHED			20
359 #define	TLS13_MT_CERTIFICATE_URL_RESERVED	21
360 #define	TLS13_MT_CERTIFICATE_STATUS_RESERVED	22
361 #define	TLS13_MT_SUPPLEMENTAL_DATA_RESERVED	23
362 #define	TLS13_MT_KEY_UPDATE			24
363 #define	TLS13_MT_MESSAGE_HASH			254
364 
365 int tls13_handshake_msg_record(struct tls13_ctx *ctx);
366 int tls13_handshake_perform(struct tls13_ctx *ctx);
367 
368 int tls13_client_init(struct tls13_ctx *ctx);
369 int tls13_server_init(struct tls13_ctx *ctx);
370 int tls13_client_connect(struct tls13_ctx *ctx);
371 int tls13_server_accept(struct tls13_ctx *ctx);
372 
373 int tls13_client_hello_send(struct tls13_ctx *ctx, CBB *cbb);
374 int tls13_client_hello_sent(struct tls13_ctx *ctx);
375 int tls13_client_hello_recv(struct tls13_ctx *ctx, CBS *cbs);
376 int tls13_client_hello_retry_send(struct tls13_ctx *ctx, CBB *cbb);
377 int tls13_client_hello_retry_recv(struct tls13_ctx *ctx, CBS *cbs);
378 int tls13_client_end_of_early_data_send(struct tls13_ctx *ctx, CBB *cbb);
379 int tls13_client_end_of_early_data_recv(struct tls13_ctx *ctx, CBS *cbs);
380 int tls13_client_certificate_send(struct tls13_ctx *ctx, CBB *cbb);
381 int tls13_client_certificate_recv(struct tls13_ctx *ctx, CBS *cbs);
382 int tls13_client_certificate_verify_send(struct tls13_ctx *ctx, CBB *cbb);
383 int tls13_client_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs);
384 int tls13_client_finished_recv(struct tls13_ctx *ctx, CBS *cbs);
385 int tls13_client_finished_send(struct tls13_ctx *ctx, CBB *cbb);
386 int tls13_client_finished_sent(struct tls13_ctx *ctx);
387 int tls13_server_hello_recv(struct tls13_ctx *ctx, CBS *cbs);
388 int tls13_server_hello_send(struct tls13_ctx *ctx, CBB *cbb);
389 int tls13_server_hello_sent(struct tls13_ctx *ctx);
390 int tls13_server_hello_retry_request_recv(struct tls13_ctx *ctx, CBS *cbs);
391 int tls13_server_hello_retry_request_send(struct tls13_ctx *ctx, CBB *cbb);
392 int tls13_server_hello_retry_request_sent(struct tls13_ctx *ctx);
393 int tls13_server_encrypted_extensions_recv(struct tls13_ctx *ctx, CBS *cbs);
394 int tls13_server_encrypted_extensions_send(struct tls13_ctx *ctx, CBB *cbb);
395 int tls13_server_certificate_recv(struct tls13_ctx *ctx, CBS *cbs);
396 int tls13_server_certificate_send(struct tls13_ctx *ctx, CBB *cbb);
397 int tls13_server_certificate_request_recv(struct tls13_ctx *ctx, CBS *cbs);
398 int tls13_server_certificate_request_send(struct tls13_ctx *ctx, CBB *cbb);
399 int tls13_server_certificate_verify_send(struct tls13_ctx *ctx, CBB *cbb);
400 int tls13_server_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs);
401 int tls13_server_finished_recv(struct tls13_ctx *ctx, CBS *cbs);
402 int tls13_server_finished_send(struct tls13_ctx *ctx, CBB *cbb);
403 int tls13_server_finished_sent(struct tls13_ctx *ctx);
404 
405 void tls13_error_clear(struct tls13_error *error);
406 int tls13_cert_add(struct tls13_ctx *ctx, CBB *cbb, X509 *cert,
407     int(*build_extensions)(SSL *s, uint16_t msg_type, CBB *cbb));
408 
409 int tls13_synthetic_handshake_message(struct tls13_ctx *ctx);
410 int tls13_clienthello_hash_init(struct tls13_ctx *ctx);
411 void tls13_clienthello_hash_clear(struct ssl_handshake_tls13_st *hs);
412 int tls13_clienthello_hash_update_bytes(struct tls13_ctx *ctx, void *data,
413     size_t len);
414 int tls13_clienthello_hash_update(struct tls13_ctx *ctx, CBS *cbs);
415 int tls13_clienthello_hash_finalize(struct tls13_ctx *ctx);
416 int tls13_clienthello_hash_validate(struct tls13_ctx *ctx);
417 
418 int tls13_error_set(struct tls13_error *error, int code, int subcode,
419     const char *file, int line, const char *fmt, ...);
420 int tls13_error_setx(struct tls13_error *error, int code, int subcode,
421     const char *file, int line, const char *fmt, ...);
422 
423 #define tls13_set_error(ctx, code, subcode, fmt, ...) \
424 	tls13_error_set(&(ctx)->error, (code), (subcode), __FILE__, __LINE__, \
425 	    (fmt), __VA_ARGS__)
426 #define tls13_set_errorx(ctx, code, subcode, fmt, ...) \
427 	tls13_error_setx(&(ctx)->error, (code), (subcode), __FILE__, __LINE__, \
428 	    (fmt), __VA_ARGS__)
429 
430 int tls13_exporter(struct tls13_ctx *ctx, const uint8_t *label, size_t label_len,
431     const uint8_t *context_value, size_t context_value_len, uint8_t *out,
432     size_t out_len);
433 
434 extern const uint8_t tls13_downgrade_12[8];
435 extern const uint8_t tls13_downgrade_11[8];
436 extern const uint8_t tls13_hello_retry_request_hash[32];
437 extern const uint8_t tls13_cert_verify_pad[64];
438 extern const uint8_t tls13_cert_client_verify_context[];
439 extern const uint8_t tls13_cert_server_verify_context[];
440 
441 __END_HIDDEN_DECLS
442 
443 #endif
444