1 /* dtls -- a very basic DTLS implementation
3 * Copyright (C) 2011--2012,2014 Olaf Bergmann <bergmann@tzi.org>
4 * Copyright (C) 2013 Hauke Mehrtens <hauke@hauke-m.de>
6 * Permission is hereby granted, free of charge, to any person
7 * obtaining a copy of this software and associated documentation
8 * files (the "Software"), to deal in the Software without
9 * restriction, including without limitation the rights to use, copy,
10 * modify, merge, publish, distribute, sublicense, and/or sell copies
11 * of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be
15 * included in all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
21 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
22 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
23 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
28 #include "dtls_config.h"
29 #include "dtls_time.h"
39 #endif /* WITH_CONTIKI */
51 # include "sha2/sha2.h"
54 #define dtls_set_version(H,V) dtls_int_to_uint16((H)->version, (V))
55 #define dtls_set_content_type(H,V) ((H)->content_type = (V) & 0xff)
56 #define dtls_set_length(H,V) ((H)->length = (V))
58 #define dtls_get_content_type(H) ((H)->content_type & 0xff)
59 #define dtls_get_version(H) dtls_uint16_to_int((H)->version)
60 #define dtls_get_epoch(H) dtls_uint16_to_int((H)->epoch)
61 #define dtls_get_sequence_number(H) dtls_uint48_to_ulong((H)->sequence_number)
62 #define dtls_get_fragment_length(H) dtls_uint24_to_int((H)->fragment_length)
65 #define HASH_FIND_PEER(head,sess,out) \
66 HASH_FIND(hh,head,sess,sizeof(session_t),out)
67 #define HASH_ADD_PEER(head,sess,add) \
68 HASH_ADD(hh,head,sess,sizeof(session_t),add)
69 #define HASH_DEL_PEER(head,delptr) \
70 HASH_DELETE(hh,head,delptr)
71 #endif /* WITH_CONTIKI */
73 #define DTLS_RH_LENGTH sizeof(dtls_record_header_t)
74 #define DTLS_HS_LENGTH sizeof(dtls_handshake_header_t)
75 #define DTLS_CH_LENGTH sizeof(dtls_client_hello_t) /* no variable length fields! */
76 #define DTLS_COOKIE_LENGTH_MAX 32
77 #define DTLS_CH_LENGTH_MAX sizeof(dtls_client_hello_t) + DTLS_COOKIE_LENGTH_MAX + 12 + 26
78 #define DTLS_HV_LENGTH sizeof(dtls_hello_verify_t)
79 #define DTLS_SH_LENGTH (2 + DTLS_RANDOM_LENGTH + 1 + 2 + 1)
80 #define DTLS_CE_LENGTH (3 + 3 + 27 + DTLS_EC_KEY_SIZE + DTLS_EC_KEY_SIZE)
81 #define DTLS_SKEXEC_LENGTH (1 + 2 + 1 + 1 + DTLS_EC_KEY_SIZE + DTLS_EC_KEY_SIZE + 1 + 1 + 2 + 70)
82 #define DTLS_SKEXEC_ECDH_ANON_LENGTH (1 + 2 + 1 + 1 + DTLS_EC_KEY_SIZE + DTLS_EC_KEY_SIZE)
83 #define DTLS_SKEXECPSK_LENGTH_MIN 2
84 #define DTLS_SKEXECPSK_LENGTH_MAX 2 + DTLS_PSK_MAX_CLIENT_IDENTITY_LEN
85 #define DTLS_CKXPSK_LENGTH_MIN 2
86 #define DTLS_CKXEC_LENGTH (1 + 1 + DTLS_EC_KEY_SIZE + DTLS_EC_KEY_SIZE)
87 #define DTLS_CV_LENGTH (1 + 1 + 2 + 1 + 1 + 1 + 1 + DTLS_EC_KEY_SIZE + 1 + 1 + DTLS_EC_KEY_SIZE)
88 #define DTLS_FIN_LENGTH 12
90 #define HS_HDR_LENGTH DTLS_RH_LENGTH + DTLS_HS_LENGTH
91 #define HV_HDR_LENGTH HS_HDR_LENGTH + DTLS_HV_LENGTH
93 #define HIGH(V) (((V) >> 8) & 0xff)
94 #define LOW(V) ((V) & 0xff)
96 #define DTLS_RECORD_HEADER(M) ((dtls_record_header_t *)(M))
97 #define DTLS_HANDSHAKE_HEADER(M) ((dtls_handshake_header_t *)(M))
99 #define HANDSHAKE(M) ((dtls_handshake_header_t *)((M) + DTLS_RH_LENGTH))
100 #define CLIENTHELLO(M) ((dtls_client_hello_t *)((M) + HS_HDR_LENGTH))
102 /* The length check here should work because dtls_*_to_int() works on
103 * unsigned char. Otherwise, broken messages could cause severe
104 * trouble. Note that this macro jumps out of the current program flow
105 * when the message is too short. Beware!
107 #define SKIP_VAR_FIELD(P,L,T) { \
108 if (L < dtls_ ## T ## _to_int(P) + sizeof(T)) \
110 L -= dtls_ ## T ## _to_int(P) + sizeof(T); \
111 P += dtls_ ## T ## _to_int(P) + sizeof(T); \
114 /* some constants for the PRF */
115 #define PRF_LABEL(Label) prf_label_##Label
116 #define PRF_LABEL_SIZE(Label) (sizeof(PRF_LABEL(Label)) - 1)
118 static const unsigned char prf_label_master[] = "master secret";
119 static const unsigned char prf_label_key[] = "key expansion";
120 static const unsigned char prf_label_client[] = "client";
121 static const unsigned char prf_label_server[] = "server";
122 static const unsigned char prf_label_finished[] = " finished";
124 /* first part of Raw public key, the is the start of the Subject Public Key */
125 static const unsigned char cert_asn1_header[] = {
126 0x30, 0x59, /* SEQUENCE, length 89 bytes */
127 0x30, 0x13, /* SEQUENCE, length 19 bytes */
128 0x06, 0x07, /* OBJECT IDENTIFIER ecPublicKey (1 2 840 10045 2 1) */
129 0x2A, 0x86, 0x48, 0xCE, 0x3D, 0x02, 0x01,
130 0x06, 0x08, /* OBJECT IDENTIFIER prime256v1 (1 2 840 10045 3 1 7) */
131 0x2A, 0x86, 0x48, 0xCE, 0x3D, 0x03, 0x01, 0x07,
132 0x03, 0x42, 0x00, /* BIT STRING, length 66 bytes, 0 bits unused */
133 0x04 /* uncompressed, followed by the r und s values of the public key */
137 PROCESS(dtls_retransmit_process, "DTLS retransmit process");
139 static dtls_context_t the_dtls_context;
141 static inline dtls_context_t *
143 return &the_dtls_context;
147 free_context(dtls_context_t *context) {
150 #else /* WITH_CONTIKI */
152 static inline dtls_context_t *
154 return (dtls_context_t *)malloc(sizeof(dtls_context_t));
158 free_context(dtls_context_t *context) {
172 dtls_enables_anon_ecdh(dtls_context_t* ctx, dtls_cipher_enable_t is_enable)
176 ctx->is_anon_ecdh_eabled = is_enable;
181 dtls_select_cipher(dtls_context_t* ctx, const dtls_cipher_t cipher)
185 ctx->selected_cipher = cipher;
189 /* Calls cb_alert() with given arguments if defined, otherwise an
190 * error message is logged and the result is -1. This is just an
193 #define CALL(Context, which, ...) \
194 ((Context)->h && (Context)->h->which \
195 ? (Context)->h->which((Context), ##__VA_ARGS__) \
199 dtls_send_multi(dtls_context_t *ctx, dtls_peer_t *peer,
200 dtls_security_parameters_t *security , session_t *session,
201 unsigned char type, uint8 *buf_array[],
202 size_t buf_len_array[], size_t buf_array_len);
205 * Sends the fragment of length \p buflen given in \p buf to the
206 * specified \p peer. The data will be MAC-protected and encrypted
207 * according to the selected cipher and split into one or more DTLS
208 * records of the specified \p type. This function returns the number
209 * of bytes that were sent, or \c -1 if an error occurred.
211 * \param ctx The DTLS context to use.
212 * \param peer The remote peer.
213 * \param type The content type of the record.
214 * \param buf The data to send.
215 * \param buflen The actual length of \p buf.
216 * \return Less than zero on error, the number of bytes written otherwise.
219 dtls_send(dtls_context_t *ctx, dtls_peer_t *peer, unsigned char type,
220 uint8 *buf, size_t buflen) {
221 return dtls_send_multi(ctx, peer, dtls_security_params(peer), &peer->session,
222 type, &buf, &buflen, 1);
226 * Stops ongoing retransmissions of handshake messages for @p peer.
228 static void dtls_stop_retransmission(dtls_context_t *context, dtls_peer_t *peer);
231 dtls_get_peer(const dtls_context_t *ctx, const session_t *session) {
232 dtls_peer_t *p = NULL;
235 HASH_FIND_PEER(ctx->peers, session, p);
236 #else /* WITH_CONTIKI */
237 for (p = list_head(ctx->peers); p; p = list_item_next(p))
238 if (dtls_session_equals(&p->session, session))
240 #endif /* WITH_CONTIKI */
246 dtls_add_peer(dtls_context_t *ctx, dtls_peer_t *peer) {
248 HASH_ADD_PEER(ctx->peers, session, peer);
249 #else /* WITH_CONTIKI */
250 list_add(ctx->peers, peer);
251 #endif /* WITH_CONTIKI */
255 dtls_write(struct dtls_context_t *ctx,
256 session_t *dst, uint8 *buf, size_t len) {
258 dtls_peer_t *peer = dtls_get_peer(ctx, dst);
260 /* Check if peer connection already exists */
261 if (!peer) { /* no ==> create one */
264 /* dtls_connect() returns a value greater than zero if a new
265 * connection attempt is made, 0 for session reuse. */
266 res = dtls_connect(ctx, dst);
268 return (res >= 0) ? 0 : res;
269 } else { /* a session exists, check if it is in state connected */
271 if (peer->state != DTLS_STATE_CONNECTED) {
274 return dtls_send(ctx, peer, DTLS_CT_APPLICATION_DATA, buf, len);
280 dtls_get_cookie(uint8 *msg, size_t msglen, uint8 **cookie) {
281 /* To access the cookie, we have to determine the session id's
282 * length and skip the whole thing. */
283 if (msglen < DTLS_HS_LENGTH + DTLS_CH_LENGTH + sizeof(uint8))
284 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
286 if (dtls_uint16_to_int(msg + DTLS_HS_LENGTH) != DTLS_VERSION)
287 return dtls_alert_fatal_create(DTLS_ALERT_PROTOCOL_VERSION);
289 msglen -= DTLS_HS_LENGTH + DTLS_CH_LENGTH;
290 msg += DTLS_HS_LENGTH + DTLS_CH_LENGTH;
292 SKIP_VAR_FIELD(msg, msglen, uint8); /* skip session id */
294 if (msglen < (*msg & 0xff) + sizeof(uint8))
295 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
297 *cookie = msg + sizeof(uint8);
298 return dtls_uint8_to_int(msg);
301 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
305 dtls_create_cookie(dtls_context_t *ctx,
307 uint8 *msg, size_t msglen,
308 uint8 *cookie, int *clen) {
309 unsigned char buf[DTLS_HMAC_MAX];
312 /* create cookie with HMAC-SHA256 over:
314 * - session parameters (only IP address?)
316 * - random gmt and bytes
319 * - compression method
322 /* We use our own buffer as hmac_context instead of a dynamic buffer
323 * created by dtls_hmac_new() to separate storage space for cookie
324 * creation from storage that is used in real sessions. Note that
325 * the buffer size must fit with the default hash algorithm (see
326 * implementation of dtls_hmac_context_new()). */
328 dtls_hmac_context_t hmac_context;
329 dtls_hmac_init(&hmac_context, ctx->cookie_secret, DTLS_COOKIE_SECRET_LENGTH);
331 dtls_hmac_update(&hmac_context,
332 (unsigned char *)&session->addr, session->size);
334 /* feed in the beginning of the Client Hello up to and including the
336 e = sizeof(dtls_client_hello_t);
337 e += (*(msg + DTLS_HS_LENGTH + e) & 0xff) + sizeof(uint8);
338 if (e + DTLS_HS_LENGTH > msglen)
339 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
341 dtls_hmac_update(&hmac_context, msg + DTLS_HS_LENGTH, e);
343 /* skip cookie bytes and length byte */
344 e += *(uint8 *)(msg + DTLS_HS_LENGTH + e) & 0xff;
346 if (e + DTLS_HS_LENGTH > msglen)
347 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
349 dtls_hmac_update(&hmac_context,
350 msg + DTLS_HS_LENGTH + e,
351 dtls_get_fragment_length(DTLS_HANDSHAKE_HEADER(msg)) - e);
353 len = dtls_hmac_finalize(&hmac_context, buf);
356 memset(cookie + len, 0, *clen - len);
360 memcpy(cookie, buf, *clen);
364 #ifdef DTLS_CHECK_CONTENTTYPE
365 /* used to check if a received datagram contains a DTLS message */
366 static char const content_types[] = {
367 DTLS_CT_CHANGE_CIPHER_SPEC,
370 DTLS_CT_APPLICATION_DATA,
376 * Checks if \p msg points to a valid DTLS record. If
380 is_record(uint8 *msg, size_t msglen) {
381 unsigned int rlen = 0;
383 if (msglen >= DTLS_RH_LENGTH /* FIXME allow empty records? */
384 #ifdef DTLS_CHECK_CONTENTTYPE
385 && strchr(content_types, msg[0])
387 && msg[1] == HIGH(DTLS_VERSION)
388 && msg[2] == LOW(DTLS_VERSION))
390 rlen = DTLS_RH_LENGTH +
391 dtls_uint16_to_int(DTLS_RECORD_HEADER(msg)->length);
393 /* we do not accept wrong length field in record header */
402 * Initializes \p buf as record header. The caller must ensure that \p
403 * buf is capable of holding at least \c sizeof(dtls_record_header_t)
404 * bytes. Increments sequence number counter of \p security.
405 * \return pointer to the next byte after the written header.
406 * The length will be set to 0 and has to be changed before sending.
408 static inline uint8 *
409 dtls_set_record_header(uint8 type, dtls_security_parameters_t *security,
412 dtls_int_to_uint8(buf, type);
413 buf += sizeof(uint8);
415 dtls_int_to_uint16(buf, DTLS_VERSION);
416 buf += sizeof(uint16);
419 dtls_int_to_uint16(buf, security->epoch);
420 buf += sizeof(uint16);
422 dtls_int_to_uint48(buf, security->rseq);
423 buf += sizeof(uint48);
425 /* increment record sequence counter by 1 */
428 memset(buf, 0, sizeof(uint16) + sizeof(uint48));
429 buf += sizeof(uint16) + sizeof(uint48);
432 memset(buf, 0, sizeof(uint16));
433 return buf + sizeof(uint16);
437 * Initializes \p buf as handshake header. The caller must ensure that \p
438 * buf is capable of holding at least \c sizeof(dtls_handshake_header_t)
439 * bytes. Increments message sequence number counter of \p peer.
440 * \return pointer to the next byte after \p buf
442 static inline uint8 *
443 dtls_set_handshake_header(uint8 type, dtls_peer_t *peer,
445 int frag_offset, int frag_length,
448 dtls_int_to_uint8(buf, type);
449 buf += sizeof(uint8);
451 dtls_int_to_uint24(buf, length);
452 buf += sizeof(uint24);
454 if (peer && peer->handshake_params) {
455 /* and copy the result to buf */
456 dtls_int_to_uint16(buf, peer->handshake_params->hs_state.mseq_s);
458 /* increment handshake message sequence counter by 1 */
459 peer->handshake_params->hs_state.mseq_s++;
461 memset(buf, 0, sizeof(uint16));
463 buf += sizeof(uint16);
465 dtls_int_to_uint24(buf, frag_offset);
466 buf += sizeof(uint24);
468 dtls_int_to_uint24(buf, frag_length);
469 buf += sizeof(uint24);
474 /** only one compression method is currently defined */
475 static uint8 compression_methods[] = {
479 /** returns true if the cipher matches TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 */
480 static inline int is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(dtls_cipher_t cipher)
483 return cipher == TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8;
486 #endif /* DTLS_ECC */
489 /** returns true if the cipher matches TLS_PSK_WITH_AES_128_CCM_8 */
490 static inline int is_tls_psk_with_aes_128_ccm_8(dtls_cipher_t cipher)
493 return cipher == TLS_PSK_WITH_AES_128_CCM_8;
496 #endif /* DTLS_PSK */
499 /** returns true if the cipher matches TLS_ECDH_anon_WITH_AES_128_CBC_SHA_256 */
500 static inline int is_tls_ecdh_anon_with_aes_128_cbc_sha_256(dtls_cipher_t cipher)
503 return cipher == TLS_ECDH_anon_WITH_AES_128_CBC_SHA_256;
510 /** returns true if the application is configured for psk */
511 static inline int is_psk_supported(dtls_context_t *ctx)
514 return ctx && ctx->h && ctx->h->get_psk_info;
517 #endif /* DTLS_PSK */
520 /** returns true if the application is configured for ecdhe_ecdsa */
521 static inline int is_ecdsa_supported(dtls_context_t *ctx, int is_client)
524 return ctx && ctx->h && ((!is_client && ctx->h->get_ecdsa_key) ||
525 (is_client && ctx->h->verify_ecdsa_key));
528 #endif /* DTLS_ECC */
531 /** Returns true if the application is configured for ecdhe_ecdsa with
532 * client authentication */
533 static inline int is_ecdsa_client_auth_supported(dtls_context_t *ctx)
536 return ctx && ctx->h && ctx->h->get_ecdsa_key && ctx->h->verify_ecdsa_key;
539 #endif /* DTLS_ECC */
542 /** returns true if ecdh_anon_with_aes_128_cbc_sha is supported */
543 static inline int is_ecdh_anon_supported(dtls_context_t *ctx)
546 return ctx && (ctx->is_anon_ecdh_eabled == DTLS_CIPHER_ENABLE);
553 * Returns @c 1 if @p code is a cipher suite other than @c
554 * TLS_NULL_WITH_NULL_NULL that we recognize.
556 * @param ctx The current DTLS context
557 * @param code The cipher suite identifier to check
558 * @param is_client 1 for a dtls client, 0 for server
559 * @return @c 1 iff @p code is recognized,
562 known_cipher(dtls_context_t *ctx, dtls_cipher_t code, int is_client) {
567 psk = is_psk_supported(ctx);
568 ecdsa = is_ecdsa_supported(ctx, is_client);
569 ecdh_anon = is_ecdh_anon_supported(ctx);
571 return (psk && is_tls_psk_with_aes_128_ccm_8(code)) ||
572 (ecdsa && is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(code)) ||
573 (ecdh_anon && is_tls_ecdh_anon_with_aes_128_cbc_sha_256(code));
577 * This method detects if we already have a established DTLS session with
578 * peer and the peer is attempting to perform a fresh handshake by sending
579 * messages with epoch = 0. This is to handle situations mentioned in
580 * RFC 6347 - section 4.2.8.
582 * @param msg The packet received from Client
583 * @param msglen Packet length
584 * @param peer peer who is the sender for this packet
585 * @return @c 1 if this is a rehandshake attempt by
589 hs_attempt_with_existing_peer(uint8_t *msg, size_t msglen,
592 if ((peer) && (peer->state == DTLS_STATE_CONNECTED)) {
593 if (msg[0] == DTLS_CT_HANDSHAKE) {
594 uint16_t msg_epoch = dtls_uint16_to_int(DTLS_RECORD_HEADER(msg)->epoch);
595 if (msg_epoch == 0) {
596 dtls_handshake_header_t * hs_header = DTLS_HANDSHAKE_HEADER(msg + DTLS_RH_LENGTH);
597 if (hs_header->msg_type == DTLS_HT_CLIENT_HELLO ||
598 hs_header->msg_type == DTLS_HT_HELLO_REQUEST) {
607 /** Dump out the cipher keys and IVs used for the symetric cipher. */
608 static void dtls_debug_keyblock(dtls_security_parameters_t *config)
610 dtls_debug("key_block (%d bytes):\n", dtls_kb_size(config, peer->role));
611 dtls_debug_dump(" client_MAC_secret",
612 dtls_kb_client_mac_secret(config, peer->role),
613 dtls_kb_mac_secret_size(config, peer->role));
615 dtls_debug_dump(" server_MAC_secret",
616 dtls_kb_server_mac_secret(config, peer->role),
617 dtls_kb_mac_secret_size(config, peer->role));
619 dtls_debug_dump(" client_write_key",
620 dtls_kb_client_write_key(config, peer->role),
621 dtls_kb_key_size(config, peer->role));
623 dtls_debug_dump(" server_write_key",
624 dtls_kb_server_write_key(config, peer->role),
625 dtls_kb_key_size(config, peer->role));
627 dtls_debug_dump(" client_IV",
628 dtls_kb_client_iv(config, peer->role),
629 dtls_kb_iv_size(config, peer->role));
631 dtls_debug_dump(" server_IV",
632 dtls_kb_server_iv(config, peer->role),
633 dtls_kb_iv_size(config, peer->role));
636 /** returns the name of the goven handshake type number.
637 * see IANA for a full list of types:
638 * https://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-7
640 static char *dtls_handshake_type_to_name(int type)
643 case DTLS_HT_HELLO_REQUEST:
644 return "hello_request";
645 case DTLS_HT_CLIENT_HELLO:
646 return "client_hello";
647 case DTLS_HT_SERVER_HELLO:
648 return "server_hello";
649 case DTLS_HT_HELLO_VERIFY_REQUEST:
650 return "hello_verify_request";
651 case DTLS_HT_CERTIFICATE:
652 return "certificate";
653 case DTLS_HT_SERVER_KEY_EXCHANGE:
654 return "server_key_exchange";
655 case DTLS_HT_CERTIFICATE_REQUEST:
656 return "certificate_request";
657 case DTLS_HT_SERVER_HELLO_DONE:
658 return "server_hello_done";
659 case DTLS_HT_CERTIFICATE_VERIFY:
660 return "certificate_verify";
661 case DTLS_HT_CLIENT_KEY_EXCHANGE:
662 return "client_key_exchange";
663 case DTLS_HT_FINISHED:
671 * Calculate the pre master secret and after that calculate the master-secret.
674 calculate_key_block(dtls_context_t *ctx,
675 dtls_handshake_parameters_t *handshake,
678 dtls_peer_type role) {
679 unsigned char *pre_master_secret;
680 int pre_master_len = 0;
681 dtls_security_parameters_t *security = dtls_security_params_next(peer);
682 uint8 master_secret[DTLS_MASTER_SECRET_LENGTH];
685 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
688 pre_master_secret = security->key_block;
690 switch (handshake->cipher) {
692 case TLS_PSK_WITH_AES_128_CCM_8: {
693 unsigned char psk[DTLS_PSK_MAX_KEY_LEN];
696 len = CALL(ctx, get_psk_info, session, DTLS_PSK_KEY,
697 handshake->keyx.psk.identity,
698 handshake->keyx.psk.id_length,
699 psk, DTLS_PSK_MAX_KEY_LEN);
701 dtls_crit("no psk key for session available\n");
704 /* Temporarily use the key_block storage space for the pre master secret. */
705 pre_master_len = dtls_psk_pre_master_secret(psk, len,
707 MAX_KEYBLOCK_LENGTH);
709 dtls_debug_hexdump("psk", psk, len);
711 memset(psk, 0, DTLS_PSK_MAX_KEY_LEN);
712 if (pre_master_len < 0) {
713 dtls_crit("the psk was too long, for the pre master secret\n");
714 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
719 #endif /* DTLS_PSK */
721 case TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8:
722 case TLS_ECDH_anon_WITH_AES_128_CBC_SHA_256: {
723 pre_master_len = dtls_ecdh_pre_master_secret(handshake->keyx.ecc.own_eph_priv,
724 handshake->keyx.ecc.other_eph_pub_x,
725 handshake->keyx.ecc.other_eph_pub_y,
726 sizeof(handshake->keyx.ecc.own_eph_priv),
728 MAX_KEYBLOCK_LENGTH);
729 if (pre_master_len < 0) {
730 dtls_crit("the curve was too long, for the pre master secret\n");
731 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
735 #endif /* DTLS_ECC */
737 dtls_crit("calculate_key_block: unknown cipher\n");
738 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
741 dtls_debug_dump("client_random", handshake->tmp.random.client, DTLS_RANDOM_LENGTH);
742 dtls_debug_dump("server_random", handshake->tmp.random.server, DTLS_RANDOM_LENGTH);
743 dtls_debug_dump("pre_master_secret", pre_master_secret, pre_master_len);
745 dtls_prf(pre_master_secret, pre_master_len,
746 PRF_LABEL(master), PRF_LABEL_SIZE(master),
747 handshake->tmp.random.client, DTLS_RANDOM_LENGTH,
748 handshake->tmp.random.server, DTLS_RANDOM_LENGTH,
750 DTLS_MASTER_SECRET_LENGTH);
752 dtls_debug_dump("master_secret", master_secret, DTLS_MASTER_SECRET_LENGTH);
754 /* create key_block from master_secret
755 * key_block = PRF(master_secret,
756 "key expansion" + tmp.random.server + tmp.random.client) */
758 dtls_prf(master_secret,
759 DTLS_MASTER_SECRET_LENGTH,
760 PRF_LABEL(key), PRF_LABEL_SIZE(key),
761 handshake->tmp.random.server, DTLS_RANDOM_LENGTH,
762 handshake->tmp.random.client, DTLS_RANDOM_LENGTH,
764 dtls_kb_size(security, role));
766 memcpy(handshake->tmp.master_secret, master_secret, DTLS_MASTER_SECRET_LENGTH);
767 dtls_debug_keyblock(security);
769 security->cipher = handshake->cipher;
770 security->compression = handshake->compression;
776 /* TODO: add a generic method which iterates over a list and searches for a specific key */
777 static int verify_ext_eliptic_curves(uint8 *data, size_t data_length) {
780 /* length of curve list */
781 i = dtls_uint16_to_int(data);
782 data += sizeof(uint16);
783 if (i + sizeof(uint16) != data_length) {
784 dtls_warn("the list of the supported elliptic curves should be tls extension length - 2\n");
785 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
788 for (i = data_length - sizeof(uint16); i > 0; i -= sizeof(uint16)) {
789 /* check if this curve is supported */
790 curve_name = dtls_uint16_to_int(data);
791 data += sizeof(uint16);
793 if (curve_name == TLS_EXT_ELLIPTIC_CURVES_SECP256R1)
797 dtls_warn("no supported elliptic curve found\n");
798 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
801 static int verify_ext_cert_type(uint8 *data, size_t data_length) {
804 /* length of cert type list */
805 i = dtls_uint8_to_int(data);
806 data += sizeof(uint8);
807 if (i + sizeof(uint8) != data_length) {
808 dtls_warn("the list of the supported certificate types should be tls extension length - 1\n");
809 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
812 for (i = data_length - sizeof(uint8); i > 0; i -= sizeof(uint8)) {
813 /* check if this cert type is supported */
814 cert_type = dtls_uint8_to_int(data);
815 data += sizeof(uint8);
817 if (cert_type == TLS_CERT_TYPE_RAW_PUBLIC_KEY)
821 dtls_warn("no supported certificate type found\n");
822 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
825 static int verify_ext_ec_point_formats(uint8 *data, size_t data_length) {
828 /* length of ec_point_formats list */
829 i = dtls_uint8_to_int(data);
830 data += sizeof(uint8);
831 if (i + sizeof(uint8) != data_length) {
832 dtls_warn("the list of the supported ec_point_formats should be tls extension length - 1\n");
833 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
836 for (i = data_length - sizeof(uint8); i > 0; i -= sizeof(uint8)) {
837 /* check if this ec_point_format is supported */
838 cert_type = dtls_uint8_to_int(data);
839 data += sizeof(uint8);
841 if (cert_type == TLS_EXT_EC_POINT_FORMATS_UNCOMPRESSED)
845 dtls_warn("no supported ec_point_format found\n");
846 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
850 * Check for some TLS Extensions used by the ECDHE_ECDSA cipher.
853 dtls_check_tls_extension(dtls_peer_t *peer,
854 uint8 *data, size_t data_length, int client_hello)
857 int ext_elliptic_curve = 0;
858 int ext_client_cert_type = 0;
859 int ext_server_cert_type = 0;
860 int ext_ec_point_formats = 0;
861 dtls_handshake_parameters_t *handshake = peer->handshake_params;
863 if (data_length < sizeof(uint16)) {
864 /* no tls extensions specified */
865 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(handshake->cipher)) {
871 /* get the length of the tls extension list */
872 j = dtls_uint16_to_int(data);
873 data += sizeof(uint16);
874 data_length -= sizeof(uint16);
879 /* check for TLS extensions needed for this cipher */
880 while (data_length) {
881 if (data_length < sizeof(uint16) * 2)
884 /* get the tls extension type */
885 i = dtls_uint16_to_int(data);
886 data += sizeof(uint16);
887 data_length -= sizeof(uint16);
889 /* get the length of the tls extension */
890 j = dtls_uint16_to_int(data);
891 data += sizeof(uint16);
892 data_length -= sizeof(uint16);
898 case TLS_EXT_ELLIPTIC_CURVES:
899 ext_elliptic_curve = 1;
900 if (verify_ext_eliptic_curves(data, j))
903 case TLS_EXT_CLIENT_CERTIFICATE_TYPE:
904 ext_client_cert_type = 1;
906 if (verify_ext_cert_type(data, j))
909 if (dtls_uint8_to_int(data) != TLS_CERT_TYPE_RAW_PUBLIC_KEY)
913 case TLS_EXT_SERVER_CERTIFICATE_TYPE:
914 ext_server_cert_type = 1;
916 if (verify_ext_cert_type(data, j))
919 if (dtls_uint8_to_int(data) != TLS_CERT_TYPE_RAW_PUBLIC_KEY)
923 case TLS_EXT_EC_POINT_FORMATS:
924 ext_ec_point_formats = 1;
925 if (verify_ext_ec_point_formats(data, j))
928 case TLS_EXT_ENCRYPT_THEN_MAC:
929 /* As only AEAD cipher suites are currently available, this
930 * extension can be skipped.
932 dtls_info("skipped encrypt-then-mac extension\n");
935 dtls_warn("unsupported tls extension: %i\n", i);
941 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(handshake->cipher) && client_hello) {
942 if (!ext_elliptic_curve || !ext_client_cert_type || !ext_server_cert_type
943 || !ext_ec_point_formats) {
944 dtls_warn("not all required tls extensions found in client hello\n");
947 } else if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(handshake->cipher) && !client_hello) {
948 if (!ext_client_cert_type || !ext_server_cert_type) {
949 dtls_warn("not all required tls extensions found in server hello\n");
956 if (client_hello && peer->state == DTLS_STATE_CONNECTED) {
957 return dtls_alert_create(DTLS_ALERT_LEVEL_WARNING, DTLS_ALERT_NO_RENEGOTIATION);
959 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
964 * Parses the ClientHello from the client and updates the internal handshake
965 * parameters with the new data for the given \p peer. When the ClientHello
966 * handshake message in \p data does not contain a cipher suite or
967 * compression method, it is copied from the the current security parameters.
969 * \param ctx The current DTLS context.
970 * \param peer The remote peer whose security parameters are about to change.
971 * \param data The handshake message with a ClientHello.
972 * \param data_length The actual size of \p data.
973 * \return \c -Something if an error occurred, \c 0 on success.
976 dtls_update_parameters(dtls_context_t *ctx,
978 uint8 *data, size_t data_length) {
981 dtls_handshake_parameters_t *config = peer->handshake_params;
982 dtls_security_parameters_t *security = dtls_security_params(peer);
985 assert(data_length > DTLS_HS_LENGTH + DTLS_CH_LENGTH);
987 /* skip the handshake header and client version information */
988 data += DTLS_HS_LENGTH + sizeof(uint16);
989 data_length -= DTLS_HS_LENGTH + sizeof(uint16);
991 /* store client random in config */
992 memcpy(config->tmp.random.client, data, DTLS_RANDOM_LENGTH);
993 data += DTLS_RANDOM_LENGTH;
994 data_length -= DTLS_RANDOM_LENGTH;
996 /* Caution: SKIP_VAR_FIELD may jump to error: */
997 SKIP_VAR_FIELD(data, data_length, uint8); /* skip session id */
998 SKIP_VAR_FIELD(data, data_length, uint8); /* skip cookie */
1000 i = dtls_uint16_to_int(data);
1001 if (data_length < i + sizeof(uint16)) {
1002 /* Looks like we do not have a cipher nor compression. This is ok
1003 * for renegotiation, but not for the initial handshake. */
1005 if (!security || security->cipher == TLS_NULL_WITH_NULL_NULL)
1008 config->cipher = security->cipher;
1009 config->compression = security->compression;
1014 data += sizeof(uint16);
1015 data_length -= sizeof(uint16) + i;
1019 config->cipher = dtls_uint16_to_int(data);
1020 ok = known_cipher(ctx, config->cipher, 0);
1021 i -= sizeof(uint16);
1022 data += sizeof(uint16);
1025 /* skip remaining ciphers */
1029 /* reset config cipher to a well-defined value */
1030 config->cipher = TLS_NULL_WITH_NULL_NULL;
1031 dtls_warn("No matching cipher found\n");
1035 if (data_length < sizeof(uint8)) {
1036 /* no compression specified, take the current compression method */
1038 config->compression = security->compression;
1040 config->compression = TLS_COMPRESSION_NULL;
1044 i = dtls_uint8_to_int(data);
1045 if (data_length < i + sizeof(uint8))
1048 data += sizeof(uint8);
1049 data_length -= sizeof(uint8) + i;
1053 for (j = 0; j < sizeof(compression_methods) / sizeof(uint8); ++j)
1054 if (dtls_uint8_to_int(data) == compression_methods[j]) {
1055 config->compression = compression_methods[j];
1059 data += sizeof(uint8);
1063 /* reset config cipher to a well-defined value */
1067 return dtls_check_tls_extension(peer, data, data_length, 1);
1069 if (peer->state == DTLS_STATE_CONNECTED) {
1070 return dtls_alert_create(DTLS_ALERT_LEVEL_WARNING, DTLS_ALERT_NO_RENEGOTIATION);
1072 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1077 * Parse the ClientKeyExchange and update the internal handshake state with
1081 check_client_keyexchange(dtls_context_t *ctx,
1082 dtls_handshake_parameters_t *handshake,
1083 uint8 *data, size_t length) {
1086 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(handshake->cipher) ||
1087 is_tls_ecdh_anon_with_aes_128_cbc_sha_256(handshake->cipher) ) {
1089 if (length < DTLS_HS_LENGTH + DTLS_CKXEC_LENGTH) {
1090 dtls_debug("The client key exchange is too short\n");
1091 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1093 data += DTLS_HS_LENGTH;
1095 if (dtls_uint8_to_int(data) != 1 + 2 * DTLS_EC_KEY_SIZE) {
1096 dtls_alert("expected 65 bytes long public point\n");
1097 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1099 data += sizeof(uint8);
1101 if (dtls_uint8_to_int(data) != 4) {
1102 dtls_alert("expected uncompressed public point\n");
1103 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1105 data += sizeof(uint8);
1107 memcpy(handshake->keyx.ecc.other_eph_pub_x, data,
1108 sizeof(handshake->keyx.ecc.other_eph_pub_x));
1109 data += sizeof(handshake->keyx.ecc.other_eph_pub_x);
1111 memcpy(handshake->keyx.ecc.other_eph_pub_y, data,
1112 sizeof(handshake->keyx.ecc.other_eph_pub_y));
1113 data += sizeof(handshake->keyx.ecc.other_eph_pub_y);
1115 #endif /* DTLS_ECC */
1117 if (is_tls_psk_with_aes_128_ccm_8(handshake->cipher)) {
1120 if (length < DTLS_HS_LENGTH + DTLS_CKXPSK_LENGTH_MIN) {
1121 dtls_debug("The client key exchange is too short\n");
1122 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1124 data += DTLS_HS_LENGTH;
1126 id_length = dtls_uint16_to_int(data);
1127 data += sizeof(uint16);
1129 if (DTLS_HS_LENGTH + DTLS_CKXPSK_LENGTH_MIN + id_length != length) {
1130 dtls_debug("The identity has a wrong length\n");
1131 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1134 if (id_length > DTLS_PSK_MAX_CLIENT_IDENTITY_LEN) {
1135 dtls_warn("please use a smaller client identity\n");
1136 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
1139 handshake->keyx.psk.id_length = id_length;
1140 memcpy(handshake->keyx.psk.identity, data, id_length);
1142 #endif /* DTLS_PSK */
1147 update_hs_hash(dtls_peer_t *peer, uint8 *data, size_t length) {
1148 dtls_debug_dump("add MAC data", data, length);
1149 dtls_hash_update(&peer->handshake_params->hs_state.hs_hash, data, length);
1153 copy_hs_hash(dtls_peer_t *peer, dtls_hash_ctx *hs_hash) {
1154 memcpy(hs_hash, &peer->handshake_params->hs_state.hs_hash,
1155 sizeof(peer->handshake_params->hs_state.hs_hash));
1158 static inline size_t
1159 finalize_hs_hash(dtls_peer_t *peer, uint8 *buf) {
1160 return dtls_hash_finalize(buf, &peer->handshake_params->hs_state.hs_hash);
1164 clear_hs_hash(dtls_peer_t *peer) {
1166 dtls_debug("clear MAC\n");
1167 dtls_hash_init(&peer->handshake_params->hs_state.hs_hash);
1171 * Checks if \p record + \p data contain a Finished message with valid
1174 * \param ctx The current DTLS context.
1175 * \param peer The remote peer of the security association.
1176 * \param data The cleartext payload of the message.
1177 * \param data_length Actual length of \p data.
1178 * \return \c 0 if the Finished message is valid, \c negative number otherwise.
1181 check_finished(dtls_context_t *ctx, dtls_peer_t *peer,
1182 uint8 *data, size_t data_length) {
1183 size_t digest_length, label_size;
1184 const unsigned char *label;
1185 unsigned char buf[DTLS_HMAC_MAX];
1187 if (data_length < DTLS_HS_LENGTH + DTLS_FIN_LENGTH)
1188 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1190 /* Use a union here to ensure that sufficient stack space is
1191 * reserved. As statebuf and verify_data are not used at the same
1192 * time, we can re-use the storage safely.
1195 unsigned char statebuf[DTLS_HASH_CTX_SIZE];
1196 unsigned char verify_data[DTLS_FIN_LENGTH];
1199 /* temporarily store hash status for roll-back after finalize */
1200 memcpy(b.statebuf, &peer->handshake_params->hs_state.hs_hash, DTLS_HASH_CTX_SIZE);
1202 digest_length = finalize_hs_hash(peer, buf);
1205 /* restore hash status */
1206 memcpy(&peer->handshake_params->hs_state.hs_hash, b.statebuf, DTLS_HASH_CTX_SIZE);
1208 if (peer->role == DTLS_CLIENT) {
1209 label = PRF_LABEL(server);
1210 label_size = PRF_LABEL_SIZE(server);
1211 } else { /* server */
1212 label = PRF_LABEL(client);
1213 label_size = PRF_LABEL_SIZE(client);
1216 dtls_prf(peer->handshake_params->tmp.master_secret,
1217 DTLS_MASTER_SECRET_LENGTH,
1219 PRF_LABEL(finished), PRF_LABEL_SIZE(finished),
1221 b.verify_data, sizeof(b.verify_data));
1223 dtls_debug_dump("d:", data + DTLS_HS_LENGTH, sizeof(b.verify_data));
1224 dtls_debug_dump("v:", b.verify_data, sizeof(b.verify_data));
1226 /* compare verify data and create DTLS alert code when they differ */
1227 return equals(data + DTLS_HS_LENGTH, b.verify_data, sizeof(b.verify_data))
1229 : dtls_alert_create(DTLS_ALERT_LEVEL_FATAL, DTLS_ALERT_HANDSHAKE_FAILURE);
1233 * Prepares the payload given in \p data for sending with
1234 * dtls_send(). The \p data is encrypted and compressed according to
1235 * the current security parameters of \p peer. The result of this
1236 * operation is put into \p sendbuf with a prepended record header of
1237 * type \p type ready for sending. As some cipher suites add a MAC
1238 * before encryption, \p data must be large enough to hold this data
1239 * as well (usually \c dtls_kb_digest_size(CURRENT_CONFIG(peer)).
1241 * \param peer The remote peer the packet will be sent to.
1242 * \param security The encryption paramater used to encrypt
1243 * \param type The content type of this record.
1244 * \param data_array Array with payloads in correct order.
1245 * \param data_len_array sizes of the payloads in correct order.
1246 * \param data_array_len The number of payloads given.
1247 * \param sendbuf The output buffer where the encrypted record
1249 * \param rlen This parameter must be initialized with the
1250 * maximum size of \p sendbuf and will be updated
1251 * to hold the actual size of the stored packet
1252 * on success. On error, the value of \p rlen is
1254 * \return Less than zero on error, or greater than zero success.
1257 dtls_prepare_record(dtls_peer_t *peer, dtls_security_parameters_t *security,
1259 uint8 *data_array[], size_t data_len_array[],
1260 size_t data_array_len,
1261 uint8 *sendbuf, size_t *rlen) {
1266 if (*rlen < DTLS_RH_LENGTH) {
1267 dtls_alert("The sendbuf (%zu bytes) is too small\n", *rlen);
1268 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
1271 p = dtls_set_record_header(type, security, sendbuf);
1274 if (!security || security->cipher == TLS_NULL_WITH_NULL_NULL) {
1275 /* no cipher suite */
1278 for (i = 0; i < data_array_len; i++) {
1279 /* check the minimum that we need for packets that are not encrypted */
1280 if (*rlen < res + DTLS_RH_LENGTH + data_len_array[i]) {
1281 dtls_debug("dtls_prepare_record: send buffer too small\n");
1282 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
1285 memcpy(p, data_array[i], data_len_array[i]);
1286 p += data_len_array[i];
1287 res += data_len_array[i];
1289 } else if (is_tls_ecdh_anon_with_aes_128_cbc_sha_256(security->cipher)) {
1291 unsigned char nonce[DTLS_CBC_IV_LENGTH];
1293 /** Add IV into body of packet in case of AES CBC mode according to RFC 5246, Section 6.2.3.2
1295 * opaque IV[SecurityParameters.record_iv_length];
1296 * block-ciphered struct {
1297 * opaque content[TLSCompressed.length];
1298 * opaque MAC[SecurityParameters.mac_length];
1299 * uint8 padding[GenericBlockCipher.padding_length];
1300 * uint8 padding_length;
1306 dtls_prng(nonce, DTLS_CBC_IV_LENGTH);
1307 memcpy(p , nonce, DTLS_CBC_IV_LENGTH);
1308 p += DTLS_CBC_IV_LENGTH;
1309 res += DTLS_CBC_IV_LENGTH;
1311 for (i = 0; i < data_array_len; i++) {
1312 /* check the minimum that we need for packets that are not encrypted */
1313 if (*rlen < res + DTLS_RH_LENGTH + data_len_array[i]) {
1314 dtls_debug("dtls_prepare_record: send buffer too small\n");
1315 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
1318 memcpy(p, data_array[i], data_len_array[i]);
1319 p += data_len_array[i];
1320 res += data_len_array[i];
1323 res = dtls_encrypt(start + DTLS_CBC_IV_LENGTH, res - DTLS_CBC_IV_LENGTH,
1324 start + DTLS_CBC_IV_LENGTH, nonce,
1325 dtls_kb_local_write_key(security, peer->role),
1326 dtls_kb_key_size(security, peer->role),
1332 res += DTLS_CBC_IV_LENGTH;
1334 } else { /* TLS_PSK_WITH_AES_128_CCM_8 or TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 */
1336 * length of additional_data for the AEAD cipher which consists of
1337 * seq_num(2+6) + type(1) + version(2) + length(2)
1339 #define A_DATA_LEN 13
1340 unsigned char nonce[DTLS_CCM_BLOCKSIZE];
1341 unsigned char A_DATA[A_DATA_LEN];
1343 if (is_tls_psk_with_aes_128_ccm_8(security->cipher)) {
1344 dtls_debug("dtls_prepare_record(): encrypt using TLS_PSK_WITH_AES_128_CCM_8\n");
1345 } else if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(security->cipher)) {
1346 dtls_debug("dtls_prepare_record(): encrypt using TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8\n");
1348 dtls_debug("dtls_prepare_record(): encrypt using unknown cipher\n");
1353 The "nonce" input to the AEAD algorithm is exactly that of [RFC5288]:
1354 the "nonce" SHALL be 12 bytes long and is constructed as follows:
1355 (this is an example of a "partially explicit" nonce; see Section
1356 3.2.1 in [RFC5116]).
1360 opaque nonce_explicit[8];
1365 In DTLS, the 64-bit seq_num is the 16-bit epoch concatenated with the
1368 When the nonce_explicit is equal to the sequence number, the CCMNonce
1369 will have the structure of the CCMNonceExample given below.
1372 uint32 client_write_IV; // low order 32-bits
1373 uint64 seq_num; // TLS sequence number
1378 uint32 server_write_IV; // low order 32-bits
1379 uint64 seq_num; // TLS sequence number
1391 memcpy(p, &DTLS_RECORD_HEADER(sendbuf)->epoch, 8);
1395 for (i = 0; i < data_array_len; i++) {
1396 /* check the minimum that we need for packets that are not encrypted */
1397 if (*rlen < res + DTLS_RH_LENGTH + data_len_array[i]) {
1398 dtls_debug("dtls_prepare_record: send buffer too small\n");
1399 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
1402 memcpy(p, data_array[i], data_len_array[i]);
1403 p += data_len_array[i];
1404 res += data_len_array[i];
1407 memset(nonce, 0, DTLS_CCM_BLOCKSIZE);
1408 memcpy(nonce, dtls_kb_local_iv(security, peer->role),
1409 dtls_kb_iv_size(security, peer->role));
1410 memcpy(nonce + dtls_kb_iv_size(security, peer->role), start, 8); /* epoch + seq_num */
1412 dtls_debug_dump("nonce:", nonce, DTLS_CCM_BLOCKSIZE);
1413 dtls_debug_dump("key:", dtls_kb_local_write_key(security, peer->role),
1414 dtls_kb_key_size(security, peer->role));
1416 /* re-use N to create additional data according to RFC 5246, Section 6.2.3.3:
1418 * additional_data = seq_num + TLSCompressed.type +
1419 * TLSCompressed.version + TLSCompressed.length;
1421 memcpy(A_DATA, &DTLS_RECORD_HEADER(sendbuf)->epoch, 8); /* epoch and seq_num */
1422 memcpy(A_DATA + 8, &DTLS_RECORD_HEADER(sendbuf)->content_type, 3); /* type and version */
1423 dtls_int_to_uint16(A_DATA + 11, res - 8); /* length */
1426 res = dtls_encrypt(start + 8, res - 8, start + 8, nonce,
1427 dtls_kb_local_write_key(security, peer->role),
1428 dtls_kb_key_size(security, peer->role),
1435 res += 8; /* increment res by size of nonce_explicit */
1436 dtls_debug_dump("message:", start, res);
1439 /* fix length of fragment in sendbuf */
1440 dtls_int_to_uint16(sendbuf + 11, res);
1442 *rlen = DTLS_RH_LENGTH + res;
1447 dtls_send_handshake_msg_hash(dtls_context_t *ctx,
1451 uint8 *data, size_t data_length,
1454 uint8 buf[DTLS_HS_LENGTH];
1455 uint8 *data_array[2];
1456 size_t data_len_array[2];
1458 dtls_security_parameters_t *security = peer ? dtls_security_params(peer) : NULL;
1460 dtls_set_handshake_header(header_type, peer, data_length, 0,
1464 update_hs_hash(peer, buf, sizeof(buf));
1466 data_array[i] = buf;
1467 data_len_array[i] = sizeof(buf);
1472 update_hs_hash(peer, data, data_length);
1474 data_array[i] = data;
1475 data_len_array[i] = data_length;
1478 dtls_debug("send handshake packet of type: %s (%i)\n",
1479 dtls_handshake_type_to_name(header_type), header_type);
1480 return dtls_send_multi(ctx, peer, security, session, DTLS_CT_HANDSHAKE,
1481 data_array, data_len_array, i);
1485 dtls_send_handshake_msg(dtls_context_t *ctx,
1488 uint8 *data, size_t data_length)
1490 return dtls_send_handshake_msg_hash(ctx, peer, &peer->session,
1491 header_type, data, data_length, 1);
1495 * Returns true if the message @p Data is a handshake message that
1496 * must be included in the calculation of verify_data in the Finished
1499 * @param Type The message type. Only handshake messages but the initial
1500 * Client Hello and Hello Verify Request are included in the hash,
1501 * @param Data The PDU to examine.
1502 * @param Length The length of @p Data.
1504 * @return @c 1 if @p Data must be included in hash, @c 0 otherwise.
1508 #define MUST_HASH(Type, Data, Length) \
1509 ((Type) == DTLS_CT_HANDSHAKE && \
1510 ((Data) != NULL) && ((Length) > 0) && \
1511 ((Data)[0] != DTLS_HT_HELLO_VERIFY_REQUEST) && \
1512 ((Data)[0] != DTLS_HT_CLIENT_HELLO || \
1513 ((Length) >= HS_HDR_LENGTH && \
1514 (dtls_uint16_to_int(DTLS_RECORD_HEADER(Data)->epoch > 0) || \
1515 (dtls_uint16_to_int(HANDSHAKE(Data)->message_seq) > 0)))))
1518 * Sends the data passed in @p buf as a DTLS record of type @p type to
1519 * the given peer. The data will be encrypted and compressed according
1520 * to the security parameters for @p peer.
1522 * @param ctx The DTLS context in effect.
1523 * @param peer The remote party where the packet is sent.
1524 * @param type The content type of this record.
1525 * @param buf The data to send.
1526 * @param buflen The number of bytes to send from @p buf.
1527 * @return Less than zero in case of an error or the number of
1528 * bytes that have been sent otherwise.
1531 dtls_send_multi(dtls_context_t *ctx, dtls_peer_t *peer,
1532 dtls_security_parameters_t *security , session_t *session,
1533 unsigned char type, uint8 *buf_array[],
1534 size_t buf_len_array[], size_t buf_array_len)
1536 /* We cannot use ctx->sendbuf here as it is reserved for collecting
1537 * the input for this function, i.e. buf == ctx->sendbuf.
1539 * TODO: check if we can use the receive buf here. This would mean
1540 * that we might not be able to handle multiple records stuffed in
1541 * one UDP datagram */
1542 unsigned char sendbuf[DTLS_MAX_BUF];
1543 size_t len = sizeof(sendbuf);
1546 size_t overall_len = 0;
1548 res = dtls_prepare_record(peer, security, type, buf_array, buf_len_array, buf_array_len, sendbuf, &len);
1553 /* if (peer && MUST_HASH(peer, type, buf, buflen)) */
1554 /* update_hs_hash(peer, buf, buflen); */
1556 dtls_debug_hexdump("send header", sendbuf, sizeof(dtls_record_header_t));
1557 for (i = 0; i < buf_array_len; i++) {
1558 dtls_debug_hexdump("send unencrypted", buf_array[i], buf_len_array[i]);
1559 overall_len += buf_len_array[i];
1562 if ((type == DTLS_CT_HANDSHAKE && buf_array[0][0] != DTLS_HT_HELLO_VERIFY_REQUEST) ||
1563 type == DTLS_CT_CHANGE_CIPHER_SPEC) {
1564 /* copy handshake messages other than HelloVerify into retransmit buffer */
1565 netq_t *n = netq_node_new(overall_len);
1569 n->t = now + 2 * CLOCK_SECOND;
1570 n->retransmit_cnt = 0;
1571 n->timeout = 2 * CLOCK_SECOND;
1573 n->epoch = (security) ? security->epoch : 0;
1576 for (i = 0; i < buf_array_len; i++) {
1577 memcpy(n->data + n->length, buf_array[i], buf_len_array[i]);
1578 n->length += buf_len_array[i];
1581 if (!netq_insert_node(ctx->sendqueue, n)) {
1582 dtls_warn("cannot add packet to retransmit buffer\n");
1586 /* must set timer within the context of the retransmit process */
1587 PROCESS_CONTEXT_BEGIN(&dtls_retransmit_process);
1588 etimer_set(&ctx->retransmit_timer, n->timeout);
1589 PROCESS_CONTEXT_END(&dtls_retransmit_process);
1590 #else /* WITH_CONTIKI */
1591 dtls_debug("copied to sendqueue\n");
1592 #endif /* WITH_CONTIKI */
1595 dtls_warn("retransmit buffer full\n");
1598 /* FIXME: copy to peer's sendqueue (after fragmentation if
1599 * necessary) and initialize retransmit timer */
1600 res = CALL(ctx, write, session, sendbuf, len);
1602 /* Guess number of bytes application data actually sent:
1603 * dtls_prepare_record() tells us in len the number of bytes to
1604 * send, res will contain the bytes actually sent. */
1605 return res <= 0 ? res : overall_len - (len - res);
1609 dtls_send_alert(dtls_context_t *ctx, dtls_peer_t *peer, dtls_alert_level_t level,
1610 dtls_alert_t description) {
1611 uint8_t msg[] = { level, description };
1613 dtls_send(ctx, peer, DTLS_CT_ALERT, msg, sizeof(msg));
1618 dtls_close(dtls_context_t *ctx, const session_t *remote) {
1622 peer = dtls_get_peer(ctx, remote);
1625 res = dtls_send_alert(ctx, peer, DTLS_ALERT_LEVEL_FATAL, DTLS_ALERT_CLOSE_NOTIFY);
1626 /* indicate tear down */
1627 peer->state = DTLS_STATE_CLOSING;
1632 static void dtls_destroy_peer(dtls_context_t *ctx, dtls_peer_t *peer, int unlink)
1634 if (peer->state != DTLS_STATE_CLOSED && peer->state != DTLS_STATE_CLOSING)
1635 dtls_close(ctx, &peer->session);
1637 #ifndef WITH_CONTIKI
1638 HASH_DEL_PEER(ctx->peers, peer);
1639 #else /* WITH_CONTIKI */
1640 list_remove(ctx->peers, peer);
1641 #endif /* WITH_CONTIKI */
1643 dtls_dsrv_log_addr(DTLS_LOG_DEBUG, "removed peer", &peer->session);
1645 dtls_free_peer(peer);
1649 * Checks a received Client Hello message for a valid cookie. When the
1650 * Client Hello contains no cookie, the function fails and a Hello
1651 * Verify Request is sent to the peer (using the write callback function
1652 * registered with \p ctx). The return value is \c -1 on error, \c 0 when
1653 * undecided, and \c 1 if the Client Hello was good.
1655 * \param ctx The DTLS context.
1656 * \param peer The remote party we are talking to, if any.
1657 * \param session Transport address of the remote peer.
1658 * \param state Current state of the connection.
1659 * \param msg The received datagram.
1660 * \param msglen Length of \p msg.
1661 * \return \c 1 if msg is a Client Hello with a valid cookie, \c 0 or
1665 dtls_verify_peer(dtls_context_t *ctx,
1668 const dtls_state_t state,
1669 uint8 *data, size_t data_length)
1671 uint8 buf[DTLS_HV_LENGTH + DTLS_COOKIE_LENGTH];
1673 int len = DTLS_COOKIE_LENGTH;
1674 uint8 *cookie = NULL;
1677 #define mycookie (buf + DTLS_HV_LENGTH)
1679 /* Store cookie where we can reuse it for the HelloVerify request. */
1680 err = dtls_create_cookie(ctx, session, data, data_length, mycookie, &len);
1684 dtls_debug_dump("create cookie", mycookie, len);
1686 assert(len == DTLS_COOKIE_LENGTH);
1688 /* Perform cookie check. */
1689 len = dtls_get_cookie(data, data_length, &cookie);
1691 dtls_warn("error while fetching the cookie, err: %i\n", err);
1695 dtls_debug_dump("compare with cookie", cookie, len);
1697 /* check if cookies match */
1698 if (len == DTLS_COOKIE_LENGTH && memcmp(cookie, mycookie, len) == 0) {
1699 dtls_debug("found matching cookie\n");
1704 dtls_debug_dump("invalid cookie", cookie, len);
1706 dtls_debug("cookie len is 0!\n");
1709 /* ClientHello did not contain any valid cookie, hence we send a
1710 * HelloVerify request. */
1712 dtls_int_to_uint16(p, DTLS_VERSION);
1713 p += sizeof(uint16);
1715 dtls_int_to_uint8(p, DTLS_COOKIE_LENGTH);
1718 assert(p == mycookie);
1720 p += DTLS_COOKIE_LENGTH;
1722 /* TODO use the same record sequence number as in the ClientHello,
1723 see 4.2.1. Denial-of-Service Countermeasures */
1724 err = dtls_send_handshake_msg_hash(ctx,
1725 state == DTLS_STATE_CONNECTED ? peer : NULL,
1727 DTLS_HT_HELLO_VERIFY_REQUEST,
1730 dtls_warn("cannot send HelloVerify request\n");
1732 return err; /* HelloVerify is sent, now we cannot do anything but wait */
1739 dtls_check_ecdsa_signature_elem(uint8 *data, size_t data_length,
1740 unsigned char **result_r,
1741 unsigned char **result_s)
1744 uint8 *data_orig = data;
1746 if (dtls_uint8_to_int(data) != TLS_EXT_SIG_HASH_ALGO_SHA256) {
1747 dtls_alert("only sha256 is supported in certificate verify\n");
1748 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1750 data += sizeof(uint8);
1751 data_length -= sizeof(uint8);
1753 if (dtls_uint8_to_int(data) != TLS_EXT_SIG_HASH_ALGO_ECDSA) {
1754 dtls_alert("only ecdsa signature is supported in client verify\n");
1755 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1757 data += sizeof(uint8);
1758 data_length -= sizeof(uint8);
1760 if (data_length < dtls_uint16_to_int(data)) {
1761 dtls_alert("signature length wrong\n");
1762 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
1764 data += sizeof(uint16);
1765 data_length -= sizeof(uint16);
1767 if (dtls_uint8_to_int(data) != 0x30) {
1768 dtls_alert("wrong ASN.1 struct, expected SEQUENCE\n");
1769 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
1771 data += sizeof(uint8);
1772 data_length -= sizeof(uint8);
1774 if (data_length < dtls_uint8_to_int(data)) {
1775 dtls_alert("signature length wrong\n");
1776 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
1778 data += sizeof(uint8);
1779 data_length -= sizeof(uint8);
1781 if (dtls_uint8_to_int(data) != 0x02) {
1782 dtls_alert("wrong ASN.1 struct, expected Integer\n");
1783 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
1785 data += sizeof(uint8);
1786 data_length -= sizeof(uint8);
1788 i = dtls_uint8_to_int(data);
1789 data += sizeof(uint8);
1790 data_length -= sizeof(uint8);
1792 /* Sometimes these values have a leeding 0 byte */
1793 *result_r = data + i - DTLS_EC_KEY_SIZE;
1798 if (dtls_uint8_to_int(data) != 0x02) {
1799 dtls_alert("wrong ASN.1 struct, expected Integer\n");
1800 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
1802 data += sizeof(uint8);
1803 data_length -= sizeof(uint8);
1805 i = dtls_uint8_to_int(data);
1806 data += sizeof(uint8);
1807 data_length -= sizeof(uint8);
1809 /* Sometimes these values have a leeding 0 byte */
1810 *result_s = data + i - DTLS_EC_KEY_SIZE;
1815 return data - data_orig;
1819 check_client_certificate_verify(dtls_context_t *ctx,
1821 uint8 *data, size_t data_length)
1823 dtls_handshake_parameters_t *config = peer->handshake_params;
1825 unsigned char *result_r;
1826 unsigned char *result_s;
1827 dtls_hash_ctx hs_hash;
1828 unsigned char sha256hash[DTLS_HMAC_DIGEST_SIZE];
1830 assert(is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(config->cipher));
1832 data += DTLS_HS_LENGTH;
1834 if (data_length < DTLS_HS_LENGTH + DTLS_CV_LENGTH) {
1835 dtls_alert("the packet length does not match the expected\n");
1836 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
1839 ret = dtls_check_ecdsa_signature_elem(data, data_length, &result_r, &result_s);
1846 copy_hs_hash(peer, &hs_hash);
1848 dtls_hash_finalize(sha256hash, &hs_hash);
1850 ret = dtls_ecdsa_verify_sig_hash(config->keyx.ecc.other_pub_x, config->keyx.ecc.other_pub_y,
1851 sizeof(config->keyx.ecc.other_pub_x),
1852 sha256hash, sizeof(sha256hash),
1853 result_r, result_s);
1856 dtls_alert("wrong signature err: %i\n", ret);
1857 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
1861 #endif /* DTLS_ECC */
1864 dtls_send_server_hello(dtls_context_t *ctx, dtls_peer_t *peer)
1866 /* Ensure that the largest message to create fits in our source
1867 * buffer. (The size of the destination buffer is checked by the
1868 * encoding function, so we do not need to guess.) */
1869 uint8 buf[DTLS_SH_LENGTH + 2 + 5 + 5 + 8 + 6];
1872 uint8 extension_size;
1873 dtls_handshake_parameters_t *handshake = peer->handshake_params;
1876 ecdsa = is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(handshake->cipher);
1878 extension_size = (ecdsa) ? 2 + 5 + 5 + 6 : 0;
1880 /* Handshake header */
1884 dtls_int_to_uint16(p, DTLS_VERSION);
1885 p += sizeof(uint16);
1887 /* Set server random: First 4 bytes are the server's Unix timestamp,
1888 * followed by 28 bytes of generate random data. */
1890 dtls_int_to_uint32(handshake->tmp.random.server, now / CLOCK_SECOND);
1891 dtls_prng(handshake->tmp.random.server + 4, 28);
1893 memcpy(p, handshake->tmp.random.server, DTLS_RANDOM_LENGTH);
1894 p += DTLS_RANDOM_LENGTH;
1896 *p++ = 0; /* no session id */
1898 if (handshake->cipher != TLS_NULL_WITH_NULL_NULL) {
1899 /* selected cipher suite */
1900 dtls_int_to_uint16(p, handshake->cipher);
1901 p += sizeof(uint16);
1903 /* selected compression method */
1904 *p++ = compression_methods[handshake->compression];
1907 if (extension_size) {
1908 /* length of the extensions */
1909 dtls_int_to_uint16(p, extension_size - 2);
1910 p += sizeof(uint16);
1914 /* client certificate type extension */
1915 dtls_int_to_uint16(p, TLS_EXT_CLIENT_CERTIFICATE_TYPE);
1916 p += sizeof(uint16);
1918 /* length of this extension type */
1919 dtls_int_to_uint16(p, 1);
1920 p += sizeof(uint16);
1922 dtls_int_to_uint8(p, TLS_CERT_TYPE_RAW_PUBLIC_KEY);
1925 /* client certificate type extension */
1926 dtls_int_to_uint16(p, TLS_EXT_SERVER_CERTIFICATE_TYPE);
1927 p += sizeof(uint16);
1929 /* length of this extension type */
1930 dtls_int_to_uint16(p, 1);
1931 p += sizeof(uint16);
1933 dtls_int_to_uint8(p, TLS_CERT_TYPE_RAW_PUBLIC_KEY);
1936 /* ec_point_formats */
1937 dtls_int_to_uint16(p, TLS_EXT_EC_POINT_FORMATS);
1938 p += sizeof(uint16);
1940 /* length of this extension type */
1941 dtls_int_to_uint16(p, 2);
1942 p += sizeof(uint16);
1944 /* number of supported formats */
1945 dtls_int_to_uint8(p, 1);
1948 dtls_int_to_uint8(p, TLS_EXT_EC_POINT_FORMATS_UNCOMPRESSED);
1952 assert(p - buf <= sizeof(buf));
1954 /* TODO use the same record sequence number as in the ClientHello,
1955 see 4.2.1. Denial-of-Service Countermeasures */
1956 return dtls_send_handshake_msg(ctx, peer, DTLS_HT_SERVER_HELLO,
1962 dtls_send_certificate_ecdsa(dtls_context_t *ctx, dtls_peer_t *peer,
1963 const dtls_ecc_key_t *key)
1965 uint8 buf[DTLS_CE_LENGTH];
1970 * Start message construction at beginning of buffer. */
1973 dtls_int_to_uint24(p, 94); /* certificates length */
1974 p += sizeof(uint24);
1976 dtls_int_to_uint24(p, 91); /* length of this certificate */
1977 p += sizeof(uint24);
1979 memcpy(p, &cert_asn1_header, sizeof(cert_asn1_header));
1980 p += sizeof(cert_asn1_header);
1982 memcpy(p, key->pub_key_x, DTLS_EC_KEY_SIZE);
1983 p += DTLS_EC_KEY_SIZE;
1985 memcpy(p, key->pub_key_y, DTLS_EC_KEY_SIZE);
1986 p += DTLS_EC_KEY_SIZE;
1988 assert(p - buf <= sizeof(buf));
1990 return dtls_send_handshake_msg(ctx, peer, DTLS_HT_CERTIFICATE,
1995 dtls_add_ecdsa_signature_elem(uint8 *p, uint32_t *point_r, uint32_t *point_s)
2000 #define R_KEY_OFFSET (1 + 1 + 2 + 1 + 1 + 1 + 1)
2001 #define S_KEY_OFFSET(len_s) (R_KEY_OFFSET + (len_s) + 1 + 1)
2002 /* store the pointer to the r component of the signature and make space */
2003 len_r = dtls_ec_key_from_uint32_asn1(point_r, DTLS_EC_KEY_SIZE, p + R_KEY_OFFSET);
2004 len_s = dtls_ec_key_from_uint32_asn1(point_s, DTLS_EC_KEY_SIZE, p + S_KEY_OFFSET(len_r));
2010 dtls_int_to_uint8(p, TLS_EXT_SIG_HASH_ALGO_SHA256);
2014 dtls_int_to_uint8(p, TLS_EXT_SIG_HASH_ALGO_ECDSA);
2017 /* length of signature */
2018 dtls_int_to_uint16(p, len_r + len_s + 2 + 2 + 2);
2019 p += sizeof(uint16);
2021 /* ASN.1 SEQUENCE */
2022 dtls_int_to_uint8(p, 0x30);
2025 dtls_int_to_uint8(p, len_r + len_s + 2 + 2);
2028 /* ASN.1 Integer r */
2029 dtls_int_to_uint8(p, 0x02);
2032 dtls_int_to_uint8(p, len_r);
2035 /* the pint r was added here */
2038 /* ASN.1 Integer s */
2039 dtls_int_to_uint8(p, 0x02);
2042 dtls_int_to_uint8(p, len_s);
2045 /* the pint s was added here */
2052 dtls_send_server_key_exchange_ecdh(dtls_context_t *ctx, dtls_peer_t *peer,
2053 const dtls_ecc_key_t *key)
2055 /* The ASN.1 Integer representation of an 32 byte unsigned int could be
2056 * 33 bytes long add space for that */
2057 uint8 buf[DTLS_SKEXEC_LENGTH + 2];
2060 uint8 *ephemeral_pub_x;
2061 uint8 *ephemeral_pub_y;
2062 uint32_t point_r[9];
2063 uint32_t point_s[9];
2065 dtls_handshake_parameters_t *config = peer->handshake_params;
2067 ecdsa = is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(peer->handshake_params->cipher);
2068 /* ServerKeyExchange
2070 * Start message construction at beginning of buffer. */
2074 /* ECCurveType curve_type: named_curve */
2075 dtls_int_to_uint8(p, 3);
2078 /* NamedCurve namedcurve: secp256r1 */
2079 dtls_int_to_uint16(p, TLS_EXT_ELLIPTIC_CURVES_SECP256R1);
2080 p += sizeof(uint16);
2082 dtls_int_to_uint8(p, 1 + 2 * DTLS_EC_KEY_SIZE);
2085 /* This should be an uncompressed point, but I do not have access to the spec. */
2086 dtls_int_to_uint8(p, 4);
2089 /* store the pointer to the x component of the pub key and make space */
2090 ephemeral_pub_x = p;
2091 p += DTLS_EC_KEY_SIZE;
2093 /* store the pointer to the y component of the pub key and make space */
2094 ephemeral_pub_y = p;
2095 p += DTLS_EC_KEY_SIZE;
2097 dtls_ecdsa_generate_key(config->keyx.ecc.own_eph_priv,
2098 ephemeral_pub_x, ephemeral_pub_y,
2102 /* sign the ephemeral and its paramaters */
2103 dtls_ecdsa_create_sig(key->priv_key, DTLS_EC_KEY_SIZE,
2104 config->tmp.random.client, DTLS_RANDOM_LENGTH,
2105 config->tmp.random.server, DTLS_RANDOM_LENGTH,
2106 key_params, p - key_params,
2109 p = dtls_add_ecdsa_signature_elem(p, point_r, point_s);
2112 assert(p - buf <= sizeof(buf));
2114 return dtls_send_handshake_msg(ctx, peer, DTLS_HT_SERVER_KEY_EXCHANGE,
2117 #endif /* DTLS_ECC */
2121 dtls_send_server_key_exchange_psk(dtls_context_t *ctx, dtls_peer_t *peer,
2122 const unsigned char *psk_hint, size_t len)
2124 uint8 buf[DTLS_SKEXECPSK_LENGTH_MAX];
2129 assert(len <= DTLS_PSK_MAX_CLIENT_IDENTITY_LEN);
2130 if (len > DTLS_PSK_MAX_CLIENT_IDENTITY_LEN) {
2131 /* should never happen */
2132 dtls_warn("psk identity hint is too long\n");
2133 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
2136 dtls_int_to_uint16(p, len);
2137 p += sizeof(uint16);
2139 memcpy(p, psk_hint, len);
2142 assert(p - buf <= sizeof(buf));
2144 return dtls_send_handshake_msg(ctx, peer, DTLS_HT_SERVER_KEY_EXCHANGE,
2147 #endif /* DTLS_PSK */
2151 dtls_send_server_certificate_request(dtls_context_t *ctx, dtls_peer_t *peer)
2158 * Start message construction at beginning of buffer. */
2161 /* certificate_types */
2162 dtls_int_to_uint8(p, 1);
2166 dtls_int_to_uint8(p, TLS_CLIENT_CERTIFICATE_TYPE_ECDSA_SIGN);
2169 /* supported_signature_algorithms */
2170 dtls_int_to_uint16(p, 2);
2171 p += sizeof(uint16);
2174 dtls_int_to_uint8(p, TLS_EXT_SIG_HASH_ALGO_SHA256);
2178 dtls_int_to_uint8(p, TLS_EXT_SIG_HASH_ALGO_ECDSA);
2181 /* certificate_authoritiess */
2182 dtls_int_to_uint16(p, 0);
2183 p += sizeof(uint16);
2185 assert(p - buf <= sizeof(buf));
2187 return dtls_send_handshake_msg(ctx, peer, DTLS_HT_CERTIFICATE_REQUEST,
2190 #endif /* DTLS_ECC */
2193 dtls_send_server_hello_done(dtls_context_t *ctx, dtls_peer_t *peer)
2198 * Start message construction at beginning of buffer. */
2200 return dtls_send_handshake_msg(ctx, peer, DTLS_HT_SERVER_HELLO_DONE,
2205 dtls_send_server_hello_msgs(dtls_context_t *ctx, dtls_peer_t *peer)
2211 res = dtls_send_server_hello(ctx, peer);
2214 dtls_debug("dtls_server_hello: cannot prepare ServerHello record\n");
2218 ecdsa = is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(peer->handshake_params->cipher);
2219 ecdh_anon = is_tls_ecdh_anon_with_aes_128_cbc_sha_256(peer->handshake_params->cipher);
2223 res = dtls_send_server_key_exchange_ecdh(ctx, peer, NULL);
2226 dtls_debug("dtls_server_hello(with ECDH): cannot prepare Server Key Exchange record\n");
2231 const dtls_ecc_key_t *ecdsa_key;
2233 res = CALL(ctx, get_ecdsa_key, &peer->session, &ecdsa_key);
2235 dtls_crit("no ecdsa certificate to send in certificate\n");
2239 res = dtls_send_certificate_ecdsa(ctx, peer, ecdsa_key);
2242 dtls_debug("dtls_server_hello: cannot prepare Certificate record\n");
2246 res = dtls_send_server_key_exchange_ecdh(ctx, peer, ecdsa_key);
2249 dtls_debug("dtls_server_hello: cannot prepare Server Key Exchange record\n");
2253 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(peer->handshake_params->cipher) &&
2254 is_ecdsa_client_auth_supported(ctx)) {
2255 res = dtls_send_server_certificate_request(ctx, peer);
2258 dtls_debug("dtls_server_hello(with ECDSA): cannot prepare certificate Request record\n");
2263 #endif /* DTLS_ECC */
2266 if (is_tls_psk_with_aes_128_ccm_8(peer->handshake_params->cipher)) {
2267 unsigned char psk_hint[DTLS_PSK_MAX_CLIENT_IDENTITY_LEN];
2270 /* The identity hint is optional, therefore we ignore the result
2271 * and check psk only. */
2272 len = CALL(ctx, get_psk_info, &peer->session, DTLS_PSK_HINT,
2273 NULL, 0, psk_hint, DTLS_PSK_MAX_CLIENT_IDENTITY_LEN);
2276 dtls_debug("dtls_server_hello: cannot create ServerKeyExchange\n");
2281 res = dtls_send_server_key_exchange_psk(ctx, peer, psk_hint, (size_t)len);
2284 dtls_debug("dtls_server_key_exchange_psk: cannot send server key exchange record\n");
2289 #endif /* DTLS_PSK */
2291 res = dtls_send_server_hello_done(ctx, peer);
2294 dtls_debug("dtls_server_hello: cannot prepare ServerHelloDone record\n");
2301 dtls_send_ccs(dtls_context_t *ctx, dtls_peer_t *peer) {
2304 return dtls_send(ctx, peer, DTLS_CT_CHANGE_CIPHER_SPEC, buf, 1);
2309 dtls_send_client_key_exchange(dtls_context_t *ctx, dtls_peer_t *peer)
2311 uint8 buf[DTLS_CKXEC_LENGTH];
2312 uint8 client_id[DTLS_PSK_MAX_CLIENT_IDENTITY_LEN];
2314 dtls_handshake_parameters_t *handshake = peer->handshake_params;
2318 switch (handshake->cipher) {
2320 case TLS_PSK_WITH_AES_128_CCM_8: {
2323 len = CALL(ctx, get_psk_info, &peer->session, DTLS_PSK_IDENTITY,
2328 dtls_crit("no psk identity set in kx\n");
2332 if (len + sizeof(uint16) > DTLS_CKXEC_LENGTH) {
2333 dtls_warn("the psk identity is too long\n");
2334 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
2337 dtls_int_to_uint16(p, len);
2338 p += sizeof(uint16);
2340 memcpy(p, client_id, len);
2345 #endif /* DTLS_PSK */
2347 case TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8:
2348 case TLS_ECDH_anon_WITH_AES_128_CBC_SHA_256: {
2349 uint8 *ephemeral_pub_x;
2350 uint8 *ephemeral_pub_y;
2352 dtls_int_to_uint8(p, 1 + 2 * DTLS_EC_KEY_SIZE);
2355 /* This should be an uncompressed point, but I do not have access to the spec. */
2356 dtls_int_to_uint8(p, 4);
2359 ephemeral_pub_x = p;
2360 p += DTLS_EC_KEY_SIZE;
2361 ephemeral_pub_y = p;
2362 p += DTLS_EC_KEY_SIZE;
2364 dtls_ecdsa_generate_key(peer->handshake_params->keyx.ecc.own_eph_priv,
2365 ephemeral_pub_x, ephemeral_pub_y,
2370 #endif /* DTLS_ECC */
2372 dtls_crit("cipher not supported\n");
2373 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
2376 assert(p - buf <= sizeof(buf));
2378 return dtls_send_handshake_msg(ctx, peer, DTLS_HT_CLIENT_KEY_EXCHANGE,
2384 dtls_send_certificate_verify_ecdh(dtls_context_t *ctx, dtls_peer_t *peer,
2385 const dtls_ecc_key_t *key)
2387 /* The ASN.1 Integer representation of an 32 byte unsigned int could be
2388 * 33 bytes long add space for that */
2389 uint8 buf[DTLS_CV_LENGTH + 2];
2391 uint32_t point_r[9];
2392 uint32_t point_s[9];
2393 dtls_hash_ctx hs_hash;
2394 unsigned char sha256hash[DTLS_HMAC_DIGEST_SIZE];
2396 /* ServerKeyExchange
2398 * Start message construction at beginning of buffer. */
2401 copy_hs_hash(peer, &hs_hash);
2403 dtls_hash_finalize(sha256hash, &hs_hash);
2405 /* sign the ephemeral and its paramaters */
2406 dtls_ecdsa_create_sig_hash(key->priv_key, DTLS_EC_KEY_SIZE,
2407 sha256hash, sizeof(sha256hash),
2410 p = dtls_add_ecdsa_signature_elem(p, point_r, point_s);
2412 assert(p - buf <= sizeof(buf));
2414 return dtls_send_handshake_msg(ctx, peer, DTLS_HT_CERTIFICATE_VERIFY,
2417 #endif /* DTLS_ECC */
2420 dtls_send_finished(dtls_context_t *ctx, dtls_peer_t *peer,
2421 const unsigned char *label, size_t labellen)
2424 uint8 hash[DTLS_HMAC_MAX];
2425 uint8 buf[DTLS_FIN_LENGTH];
2426 dtls_hash_ctx hs_hash;
2429 copy_hs_hash(peer, &hs_hash);
2431 length = dtls_hash_finalize(hash, &hs_hash);
2433 dtls_prf(peer->handshake_params->tmp.master_secret,
2434 DTLS_MASTER_SECRET_LENGTH,
2436 PRF_LABEL(finished), PRF_LABEL_SIZE(finished),
2438 p, DTLS_FIN_LENGTH);
2440 dtls_debug_dump("server finished MAC", p, DTLS_FIN_LENGTH);
2442 p += DTLS_FIN_LENGTH;
2444 assert(p - buf <= sizeof(buf));
2446 return dtls_send_handshake_msg(ctx, peer, DTLS_HT_FINISHED,
2451 dtls_send_client_hello(dtls_context_t *ctx, dtls_peer_t *peer,
2452 uint8 cookie[], size_t cookie_length) {
2453 uint8 buf[DTLS_CH_LENGTH_MAX];
2455 uint8_t cipher_size;
2456 uint8_t extension_size;
2460 dtls_handshake_parameters_t *handshake = peer->handshake_params;
2463 switch(ctx->selected_cipher)
2465 case TLS_PSK_WITH_AES_128_CCM_8:
2466 psk = is_psk_supported(ctx);
2468 case TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8:
2469 ecdsa = is_ecdsa_supported(ctx, 1);
2471 case TLS_ECDH_anon_WITH_AES_128_CBC_SHA_256:
2472 ecdh_anon = is_ecdh_anon_supported(ctx);
2475 psk = is_psk_supported(ctx);
2476 ecdsa = is_ecdsa_supported(ctx, 1);
2477 ecdh_anon = is_ecdh_anon_supported(ctx);
2481 cipher_size = 2 + (ecdsa ? 2 : 0) + (psk ? 2 : 0) + (ecdh_anon ? 2 : 0);
2482 extension_size = (ecdsa) ? (2 + 6 + 6 + 8 + 6) : 0;
2484 if (cipher_size == 0) {
2485 dtls_crit("no cipher callbacks implemented\n");
2488 dtls_int_to_uint16(p, DTLS_VERSION);
2489 p += sizeof(uint16);
2491 if (cookie_length > DTLS_COOKIE_LENGTH_MAX) {
2492 dtls_warn("the cookie is too long\n");
2493 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
2496 if (cookie_length == 0) {
2497 /* Set client random: First 4 bytes are the client's Unix timestamp,
2498 * followed by 28 bytes of generate random data. */
2500 dtls_int_to_uint32(handshake->tmp.random.client, now / CLOCK_SECOND);
2501 dtls_prng(handshake->tmp.random.client + sizeof(uint32),
2502 DTLS_RANDOM_LENGTH - sizeof(uint32));
2504 /* we must use the same Client Random as for the previous request */
2505 memcpy(p, handshake->tmp.random.client, DTLS_RANDOM_LENGTH);
2506 p += DTLS_RANDOM_LENGTH;
2508 /* session id (length 0) */
2509 dtls_int_to_uint8(p, 0);
2513 dtls_int_to_uint8(p, cookie_length);
2515 if (cookie_length != 0) {
2516 memcpy(p, cookie, cookie_length);
2520 /* add known cipher(s) */
2521 dtls_int_to_uint16(p, cipher_size - 2);
2522 p += sizeof(uint16);
2525 dtls_int_to_uint16(p, TLS_ECDH_anon_WITH_AES_128_CBC_SHA_256);
2526 p += sizeof(uint16);
2529 dtls_int_to_uint16(p, TLS_PSK_WITH_AES_128_CCM_8);
2530 p += sizeof(uint16);
2533 dtls_int_to_uint16(p, TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8);
2534 p += sizeof(uint16);
2537 /* compression method */
2538 dtls_int_to_uint8(p, 1);
2541 dtls_int_to_uint8(p, TLS_COMPRESSION_NULL);
2544 if (extension_size) {
2545 /* length of the extensions */
2546 dtls_int_to_uint16(p, extension_size - 2);
2547 p += sizeof(uint16);
2551 /* client certificate type extension */
2552 dtls_int_to_uint16(p, TLS_EXT_CLIENT_CERTIFICATE_TYPE);
2553 p += sizeof(uint16);
2555 /* length of this extension type */
2556 dtls_int_to_uint16(p, 2);
2557 p += sizeof(uint16);
2559 /* length of the list */
2560 dtls_int_to_uint8(p, 1);
2563 dtls_int_to_uint8(p, TLS_CERT_TYPE_RAW_PUBLIC_KEY);
2566 /* client certificate type extension */
2567 dtls_int_to_uint16(p, TLS_EXT_SERVER_CERTIFICATE_TYPE);
2568 p += sizeof(uint16);
2570 /* length of this extension type */
2571 dtls_int_to_uint16(p, 2);
2572 p += sizeof(uint16);
2574 /* length of the list */
2575 dtls_int_to_uint8(p, 1);
2578 dtls_int_to_uint8(p, TLS_CERT_TYPE_RAW_PUBLIC_KEY);
2581 /* elliptic_curves */
2582 dtls_int_to_uint16(p, TLS_EXT_ELLIPTIC_CURVES);
2583 p += sizeof(uint16);
2585 /* length of this extension type */
2586 dtls_int_to_uint16(p, 4);
2587 p += sizeof(uint16);
2589 /* length of the list */
2590 dtls_int_to_uint16(p, 2);
2591 p += sizeof(uint16);
2593 dtls_int_to_uint16(p, TLS_EXT_ELLIPTIC_CURVES_SECP256R1);
2594 p += sizeof(uint16);
2596 /* ec_point_formats */
2597 dtls_int_to_uint16(p, TLS_EXT_EC_POINT_FORMATS);
2598 p += sizeof(uint16);
2600 /* length of this extension type */
2601 dtls_int_to_uint16(p, 2);
2602 p += sizeof(uint16);
2604 /* number of supported formats */
2605 dtls_int_to_uint8(p, 1);
2608 dtls_int_to_uint8(p, TLS_EXT_EC_POINT_FORMATS_UNCOMPRESSED);
2612 assert(p - buf <= sizeof(buf));
2614 if (cookie_length != 0)
2615 clear_hs_hash(peer);
2617 return dtls_send_handshake_msg_hash(ctx, peer, &peer->session,
2618 DTLS_HT_CLIENT_HELLO,
2619 buf, p - buf, cookie_length != 0);
2623 check_server_hello(dtls_context_t *ctx,
2625 uint8 *data, size_t data_length)
2627 dtls_handshake_parameters_t *handshake = peer->handshake_params;
2629 /* This function is called when we expect a ServerHello (i.e. we
2630 * have sent a ClientHello). We might instead receive a HelloVerify
2631 * request containing a cookie. If so, we must repeat the
2632 * ClientHello with the given Cookie.
2634 if (data_length < DTLS_HS_LENGTH + DTLS_HS_LENGTH)
2635 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2637 update_hs_hash(peer, data, data_length);
2639 /* FIXME: check data_length before accessing fields */
2641 /* Get the server's random data and store selected cipher suite
2642 * and compression method (like dtls_update_parameters().
2643 * Then calculate master secret and wait for ServerHelloDone. When received,
2644 * send ClientKeyExchange (?) and ChangeCipherSpec + ClientFinished. */
2646 /* check server version */
2647 data += DTLS_HS_LENGTH;
2648 data_length -= DTLS_HS_LENGTH;
2650 if (dtls_uint16_to_int(data) != DTLS_VERSION) {
2651 dtls_alert("unknown DTLS version\n");
2652 return dtls_alert_fatal_create(DTLS_ALERT_PROTOCOL_VERSION);
2655 data += sizeof(uint16); /* skip version field */
2656 data_length -= sizeof(uint16);
2658 /* store server random data */
2659 memcpy(handshake->tmp.random.server, data, DTLS_RANDOM_LENGTH);
2660 /* skip server random */
2661 data += DTLS_RANDOM_LENGTH;
2662 data_length -= DTLS_RANDOM_LENGTH;
2664 SKIP_VAR_FIELD(data, data_length, uint8); /* skip session id */
2666 /* Check cipher suite. As we offer all we have, it is sufficient
2667 * to check if the cipher suite selected by the server is in our
2668 * list of known cipher suites. Subsets are not supported. */
2669 handshake->cipher = dtls_uint16_to_int(data);
2670 if (!known_cipher(ctx, handshake->cipher, 1)) {
2671 dtls_alert("unsupported cipher 0x%02x 0x%02x\n",
2673 return dtls_alert_fatal_create(DTLS_ALERT_INSUFFICIENT_SECURITY);
2675 data += sizeof(uint16);
2676 data_length -= sizeof(uint16);
2678 /* Check if NULL compression was selected. We do not know any other. */
2679 if (dtls_uint8_to_int(data) != TLS_COMPRESSION_NULL) {
2680 dtls_alert("unsupported compression method 0x%02x\n", data[0]);
2681 return dtls_alert_fatal_create(DTLS_ALERT_INSUFFICIENT_SECURITY);
2683 data += sizeof(uint8);
2684 data_length -= sizeof(uint8);
2686 return dtls_check_tls_extension(peer, data, data_length, 0);
2689 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2693 check_server_hello_verify_request(dtls_context_t *ctx,
2695 uint8 *data, size_t data_length)
2697 dtls_hello_verify_t *hv;
2700 if (data_length < DTLS_HS_LENGTH + DTLS_HV_LENGTH)
2701 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2703 hv = (dtls_hello_verify_t *)(data + DTLS_HS_LENGTH);
2705 res = dtls_send_client_hello(ctx, peer, hv->cookie, hv->cookie_length);
2708 dtls_warn("cannot send ClientHello\n");
2715 check_server_certificate(dtls_context_t *ctx,
2717 uint8 *data, size_t data_length)
2720 dtls_handshake_parameters_t *config = peer->handshake_params;
2722 update_hs_hash(peer, data, data_length);
2724 assert(is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(config->cipher));
2726 data += DTLS_HS_LENGTH;
2728 if (dtls_uint24_to_int(data) != 94) {
2729 dtls_alert("expect length of 94 bytes for server certificate message\n");
2730 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2732 data += sizeof(uint24);
2734 if (dtls_uint24_to_int(data) != 91) {
2735 dtls_alert("expect length of 91 bytes for certificate\n");
2736 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2738 data += sizeof(uint24);
2740 if (memcmp(data, cert_asn1_header, sizeof(cert_asn1_header))) {
2741 dtls_alert("got an unexpected Subject public key format\n");
2742 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2744 data += sizeof(cert_asn1_header);
2746 memcpy(config->keyx.ecc.other_pub_x, data,
2747 sizeof(config->keyx.ecc.other_pub_x));
2748 data += sizeof(config->keyx.ecc.other_pub_x);
2750 memcpy(config->keyx.ecc.other_pub_y, data,
2751 sizeof(config->keyx.ecc.other_pub_y));
2752 data += sizeof(config->keyx.ecc.other_pub_y);
2754 err = CALL(ctx, verify_ecdsa_key, &peer->session,
2755 config->keyx.ecc.other_pub_x,
2756 config->keyx.ecc.other_pub_y,
2757 sizeof(config->keyx.ecc.other_pub_x));
2759 dtls_warn("The certificate was not accepted\n");
2767 check_server_key_exchange_ecdsa(dtls_context_t *ctx,
2769 uint8 *data, size_t data_length)
2771 dtls_handshake_parameters_t *config = peer->handshake_params;
2773 unsigned char *result_r;
2774 unsigned char *result_s;
2775 unsigned char *key_params;
2777 update_hs_hash(peer, data, data_length);
2779 assert(is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(config->cipher));
2781 data += DTLS_HS_LENGTH;
2783 if (data_length < DTLS_HS_LENGTH + DTLS_SKEXEC_LENGTH) {
2784 dtls_alert("the packet length does not match the expected\n");
2785 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2789 if (dtls_uint8_to_int(data) != TLS_EC_CURVE_TYPE_NAMED_CURVE) {
2790 dtls_alert("Only named curves supported\n");
2791 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
2793 data += sizeof(uint8);
2794 data_length -= sizeof(uint8);
2796 if (dtls_uint16_to_int(data) != TLS_EXT_ELLIPTIC_CURVES_SECP256R1) {
2797 dtls_alert("secp256r1 supported\n");
2798 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
2800 data += sizeof(uint16);
2801 data_length -= sizeof(uint16);
2803 if (dtls_uint8_to_int(data) != 1 + 2 * DTLS_EC_KEY_SIZE) {
2804 dtls_alert("expected 65 bytes long public point\n");
2805 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
2807 data += sizeof(uint8);
2808 data_length -= sizeof(uint8);
2810 if (dtls_uint8_to_int(data) != 4) {
2811 dtls_alert("expected uncompressed public point\n");
2812 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2814 data += sizeof(uint8);
2815 data_length -= sizeof(uint8);
2817 memcpy(config->keyx.ecc.other_eph_pub_x, data, sizeof(config->keyx.ecc.other_eph_pub_y));
2818 data += sizeof(config->keyx.ecc.other_eph_pub_y);
2819 data_length -= sizeof(config->keyx.ecc.other_eph_pub_y);
2821 memcpy(config->keyx.ecc.other_eph_pub_y, data, sizeof(config->keyx.ecc.other_eph_pub_y));
2822 data += sizeof(config->keyx.ecc.other_eph_pub_y);
2823 data_length -= sizeof(config->keyx.ecc.other_eph_pub_y);
2825 ret = dtls_check_ecdsa_signature_elem(data, data_length, &result_r, &result_s);
2832 ret = dtls_ecdsa_verify_sig(config->keyx.ecc.other_pub_x, config->keyx.ecc.other_pub_y,
2833 sizeof(config->keyx.ecc.other_pub_x),
2834 config->tmp.random.client, DTLS_RANDOM_LENGTH,
2835 config->tmp.random.server, DTLS_RANDOM_LENGTH,
2837 1 + 2 + 1 + 1 + (2 * DTLS_EC_KEY_SIZE),
2838 result_r, result_s);
2841 dtls_alert("wrong signature\n");
2842 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
2848 check_server_key_exchange_ecdh(dtls_context_t *ctx,
2850 uint8 *data, size_t data_length)
2852 dtls_handshake_parameters_t *config = peer->handshake_params;
2854 update_hs_hash(peer, data, data_length);
2856 assert(is_tls_ecdh_anon_with_aes_128_cbc_sha_256(config->cipher));
2858 data += DTLS_HS_LENGTH;
2860 if (data_length < DTLS_HS_LENGTH + DTLS_SKEXEC_ECDH_ANON_LENGTH) {
2861 dtls_alert("the packet length does not match the expected\n");
2862 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2865 if (dtls_uint8_to_int(data) != TLS_EC_CURVE_TYPE_NAMED_CURVE) {
2866 dtls_alert("Only named curves supported\n");
2867 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
2869 data += sizeof(uint8);
2870 data_length -= sizeof(uint8);
2872 if (dtls_uint16_to_int(data) != TLS_EXT_ELLIPTIC_CURVES_SECP256R1) {
2873 dtls_alert("secp256r1 supported\n");
2874 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
2876 data += sizeof(uint16);
2877 data_length -= sizeof(uint16);
2879 if (dtls_uint8_to_int(data) != 1 + 2 * DTLS_EC_KEY_SIZE) {
2880 dtls_alert("expected 65 bytes long public point\n");
2881 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
2883 data += sizeof(uint8);
2884 data_length -= sizeof(uint8);
2886 if (dtls_uint8_to_int(data) != 4) {
2887 dtls_alert("expected uncompressed public point\n");
2888 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2890 data += sizeof(uint8);
2891 data_length -= sizeof(uint8);
2893 memcpy(config->keyx.ecc.other_eph_pub_x, data, sizeof(config->keyx.ecc.other_eph_pub_x));
2894 data += sizeof(config->keyx.ecc.other_eph_pub_x);
2895 data_length -= sizeof(config->keyx.ecc.other_eph_pub_x);
2897 memcpy(config->keyx.ecc.other_eph_pub_y, data, sizeof(config->keyx.ecc.other_eph_pub_y));
2898 data += sizeof(config->keyx.ecc.other_eph_pub_y);
2899 data_length -= sizeof(config->keyx.ecc.other_eph_pub_y);
2904 #endif /* DTLS_ECC */
2908 check_server_key_exchange_psk(dtls_context_t *ctx,
2910 uint8 *data, size_t data_length)
2912 dtls_handshake_parameters_t *config = peer->handshake_params;
2915 update_hs_hash(peer, data, data_length);
2917 assert(is_tls_psk_with_aes_128_ccm_8(config->cipher));
2919 data += DTLS_HS_LENGTH;
2921 if (data_length < DTLS_HS_LENGTH + DTLS_SKEXECPSK_LENGTH_MIN) {
2922 dtls_alert("the packet length does not match the expected\n");
2923 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2926 len = dtls_uint16_to_int(data);
2927 data += sizeof(uint16);
2929 if (len != data_length - DTLS_HS_LENGTH - sizeof(uint16)) {
2930 dtls_warn("the length of the server identity hint is worng\n");
2931 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2934 if (len > DTLS_PSK_MAX_CLIENT_IDENTITY_LEN) {
2935 dtls_warn("please use a smaller server identity hint\n");
2936 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
2939 /* store the psk_identity_hint in config->keyx.psk for later use */
2940 config->keyx.psk.id_length = len;
2941 memcpy(config->keyx.psk.identity, data, len);
2944 #endif /* DTLS_PSK */
2947 check_certificate_request(dtls_context_t *ctx,
2949 uint8 *data, size_t data_length)
2956 update_hs_hash(peer, data, data_length);
2958 assert(is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(peer->handshake_params->cipher));
2960 data += DTLS_HS_LENGTH;
2962 if (data_length < DTLS_HS_LENGTH + 5) {
2963 dtls_alert("the packet length does not match the expected\n");
2964 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2967 i = dtls_uint8_to_int(data);
2968 data += sizeof(uint8);
2969 if (i + 1 > data_length) {
2970 dtls_alert("the cerfificate types are too long\n");
2971 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2975 for (; i > 0 ; i -= sizeof(uint8)) {
2976 if (dtls_uint8_to_int(data) == TLS_CLIENT_CERTIFICATE_TYPE_ECDSA_SIGN
2978 auth_alg = dtls_uint8_to_int(data);
2979 data += sizeof(uint8);
2982 if (auth_alg != TLS_CLIENT_CERTIFICATE_TYPE_ECDSA_SIGN) {
2983 dtls_alert("the request authentication algorithm is not supproted\n");
2984 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
2987 i = dtls_uint16_to_int(data);
2988 data += sizeof(uint16);
2989 if (i + 1 > data_length) {
2990 dtls_alert("the signature and hash algorithm list is too long\n");
2991 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
2996 for (; i > 0 ; i -= sizeof(uint16)) {
2997 int current_hash_alg;
2998 int current_sig_alg;
3000 current_hash_alg = dtls_uint8_to_int(data);
3001 data += sizeof(uint8);
3002 current_sig_alg = dtls_uint8_to_int(data);
3003 data += sizeof(uint8);
3005 if (current_hash_alg == TLS_EXT_SIG_HASH_ALGO_SHA256 && hash_alg == 0 &&
3006 current_sig_alg == TLS_EXT_SIG_HASH_ALGO_ECDSA && sig_alg == 0) {
3007 hash_alg = current_hash_alg;
3008 sig_alg = current_sig_alg;
3012 if (hash_alg != TLS_EXT_SIG_HASH_ALGO_SHA256 ||
3013 sig_alg != TLS_EXT_SIG_HASH_ALGO_ECDSA) {
3014 dtls_alert("no supported hash and signature algorithem\n");
3015 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
3018 /* common names are ignored */
3020 peer->handshake_params->do_client_auth = 1;
3025 check_server_hellodone(dtls_context_t *ctx,
3027 uint8 *data, size_t data_length)
3031 const dtls_ecc_key_t *ecdsa_key;
3032 #endif /* DTLS_ECC */
3034 dtls_handshake_parameters_t *handshake = peer->handshake_params;
3036 /* calculate master key, send CCS */
3038 update_hs_hash(peer, data, data_length);
3041 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(handshake->cipher) && handshake->do_client_auth) {
3043 res = CALL(ctx, get_ecdsa_key, &peer->session, &ecdsa_key);
3045 dtls_crit("no ecdsa certificate to send in certificate\n");
3049 res = dtls_send_certificate_ecdsa(ctx, peer, ecdsa_key);
3052 dtls_debug("dtls_server_hello: cannot prepare Certificate record\n");
3056 #endif /* DTLS_ECC */
3058 /* send ClientKeyExchange */
3059 res = dtls_send_client_key_exchange(ctx, peer);
3062 dtls_debug("cannot send KeyExchange message\n");
3067 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(handshake->cipher) && handshake->do_client_auth) {
3069 res = dtls_send_certificate_verify_ecdh(ctx, peer, ecdsa_key);
3072 dtls_debug("dtls_server_hello: cannot prepare Certificate record\n");
3076 #endif /* DTLS_ECC */
3078 res = calculate_key_block(ctx, handshake, peer,
3079 &peer->session, peer->role);
3084 res = dtls_send_ccs(ctx, peer);
3086 dtls_debug("cannot send CCS message\n");
3090 /* and switch cipher suite */
3091 dtls_security_params_switch(peer);
3093 /* Client Finished */
3094 return dtls_send_finished(ctx, peer, PRF_LABEL(client), PRF_LABEL_SIZE(client));
3098 decrypt_verify(dtls_peer_t *peer, uint8 *packet, size_t length,
3101 dtls_record_header_t *header = DTLS_RECORD_HEADER(packet);
3102 dtls_security_parameters_t *security = dtls_security_params_epoch(peer, dtls_get_epoch(header));
3105 *cleartext = (uint8 *)packet + sizeof(dtls_record_header_t);
3106 clen = length - sizeof(dtls_record_header_t);
3109 dtls_alert("No security context for epoch: %i\n", dtls_get_epoch(header));
3113 if (security->cipher == TLS_NULL_WITH_NULL_NULL) {
3114 /* no cipher suite selected */
3116 } else if (is_tls_ecdh_anon_with_aes_128_cbc_sha_256(security->cipher)) {
3118 unsigned char nonce[DTLS_CBC_IV_LENGTH];
3120 if (clen < (DTLS_CBC_IV_LENGTH + DTLS_HMAC_DIGEST_SIZE)) /* need at least IV and MAC */
3123 memcpy(nonce, *cleartext , DTLS_CBC_IV_LENGTH);
3124 clen -= DTLS_CBC_IV_LENGTH;
3125 *cleartext += DTLS_CBC_IV_LENGTH ;
3127 clen = dtls_decrypt(*cleartext, clen, *cleartext, nonce,
3128 dtls_kb_remote_write_key(security, peer->role),
3129 dtls_kb_key_size(security, peer->role),
3133 } else { /* TLS_PSK_WITH_AES_128_CCM_8 or TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 */
3135 * length of additional_data for the AEAD cipher which consists of
3136 * seq_num(2+6) + type(1) + version(2) + length(2)
3138 #define A_DATA_LEN 13
3139 unsigned char nonce[DTLS_CCM_BLOCKSIZE];
3140 unsigned char A_DATA[A_DATA_LEN];
3142 if (clen < 16) /* need at least IV and MAC */
3145 memset(nonce, 0, DTLS_CCM_BLOCKSIZE);
3146 memcpy(nonce, dtls_kb_remote_iv(security, peer->role),
3147 dtls_kb_iv_size(security, peer->role));
3149 /* read epoch and seq_num from message */
3150 memcpy(nonce + dtls_kb_iv_size(security, peer->role), *cleartext, 8);
3154 dtls_debug_dump("nonce", nonce, DTLS_CCM_BLOCKSIZE);
3155 dtls_debug_dump("key", dtls_kb_remote_write_key(security, peer->role),
3156 dtls_kb_key_size(security, peer->role));
3157 dtls_debug_dump("ciphertext", *cleartext, clen);
3159 /* re-use N to create additional data according to RFC 5246, Section 6.2.3.3:
3161 * additional_data = seq_num + TLSCompressed.type +
3162 * TLSCompressed.version + TLSCompressed.length;
3164 memcpy(A_DATA, &DTLS_RECORD_HEADER(packet)->epoch, 8); /* epoch and seq_num */
3165 memcpy(A_DATA + 8, &DTLS_RECORD_HEADER(packet)->content_type, 3); /* type and version */
3166 dtls_int_to_uint16(A_DATA + 11, clen - 8); /* length without nonce_explicit */
3168 clen = dtls_decrypt(*cleartext, clen, *cleartext, nonce,
3169 dtls_kb_remote_write_key(security, peer->role),
3170 dtls_kb_key_size(security, peer->role),
3176 dtls_warn("decryption failed\n");
3179 dtls_debug("decrypt_verify(): found %i bytes cleartext\n", clen);
3181 dtls_security_params_free_other(peer);
3182 dtls_debug_dump("cleartext", *cleartext, clen);
3189 dtls_send_hello_request(dtls_context_t *ctx, dtls_peer_t *peer)
3191 return dtls_send_handshake_msg_hash(ctx, peer, &peer->session,
3192 DTLS_HT_HELLO_REQUEST,
3197 dtls_renegotiate(dtls_context_t *ctx, const session_t *dst)
3199 dtls_peer_t *peer = NULL;
3202 peer = dtls_get_peer(ctx, dst);
3207 if (peer->state != DTLS_STATE_CONNECTED)
3210 peer->handshake_params = dtls_handshake_new();
3211 if (!peer->handshake_params)
3214 peer->handshake_params->hs_state.mseq_r = 0;
3215 peer->handshake_params->hs_state.mseq_s = 0;
3217 if (peer->role == DTLS_CLIENT) {
3218 /* send ClientHello with empty Cookie */
3219 err = dtls_send_client_hello(ctx, peer, NULL, 0);
3221 dtls_warn("cannot send ClientHello\n");
3223 peer->state = DTLS_STATE_CLIENTHELLO;
3225 } else if (peer->role == DTLS_SERVER) {
3226 return dtls_send_hello_request(ctx, peer);
3233 handle_handshake_msg(dtls_context_t *ctx, dtls_peer_t *peer, session_t *session,
3234 const dtls_peer_type role, const dtls_state_t state,
3235 uint8 *data, size_t data_length) {
3239 /* This will clear the retransmission buffer if we get an expected
3240 * handshake message. We have to make sure that no handshake message
3241 * should get expected when we still should retransmit something, when
3242 * we do everything accordingly to the DTLS 1.2 standard this should
3243 * not be a problem. */
3245 dtls_stop_retransmission(ctx, peer);
3248 /* The following switch construct handles the given message with
3249 * respect to the current internal state for this peer. In case of
3250 * error, it is left with return 0. */
3252 dtls_debug("handle handshake packet of type: %s (%i)\n",
3253 dtls_handshake_type_to_name(data[0]), data[0]);
3256 /************************************************************************
3258 ************************************************************************/
3259 case DTLS_HT_HELLO_VERIFY_REQUEST:
3261 if (state != DTLS_STATE_CLIENTHELLO) {
3262 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3265 err = check_server_hello_verify_request(ctx, peer, data, data_length);
3267 dtls_warn("error in check_server_hello_verify_request err: %i\n", err);
3272 case DTLS_HT_SERVER_HELLO:
3274 if (state != DTLS_STATE_CLIENTHELLO) {
3275 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3278 err = check_server_hello(ctx, peer, data, data_length);
3280 dtls_warn("error in check_server_hello err: %i\n", err);
3283 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(peer->handshake_params->cipher))
3284 peer->state = DTLS_STATE_WAIT_SERVERCERTIFICATE; //ecdsa
3285 else if (is_tls_ecdh_anon_with_aes_128_cbc_sha_256(peer->handshake_params->cipher))
3286 peer->state = DTLS_STATE_WAIT_SERVERKEYEXCHANGE; //ecdh
3288 peer->state = DTLS_STATE_WAIT_SERVERHELLODONE; //psk
3289 /* update_hs_hash(peer, data, data_length); */
3294 case DTLS_HT_CERTIFICATE:
3296 if ((role == DTLS_CLIENT && state != DTLS_STATE_WAIT_SERVERCERTIFICATE) ||
3297 (role == DTLS_SERVER && state != DTLS_STATE_WAIT_CLIENTCERTIFICATE)) {
3298 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3300 err = check_server_certificate(ctx, peer, data, data_length);
3302 dtls_warn("error in check_server_certificate err: %i\n", err);
3305 if (role == DTLS_CLIENT) {
3306 peer->state = DTLS_STATE_WAIT_SERVERKEYEXCHANGE;
3307 } else if (role == DTLS_SERVER){
3308 peer->state = DTLS_STATE_WAIT_CLIENTKEYEXCHANGE;
3310 /* update_hs_hash(peer, data, data_length); */
3313 #endif /* DTLS_ECC */
3315 case DTLS_HT_SERVER_KEY_EXCHANGE:
3318 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(peer->handshake_params->cipher)) {
3319 if (state != DTLS_STATE_WAIT_SERVERKEYEXCHANGE) {
3320 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3322 err = check_server_key_exchange_ecdsa(ctx, peer, data, data_length);
3325 if (is_tls_ecdh_anon_with_aes_128_cbc_sha_256(peer->handshake_params->cipher)) {
3326 if (state != DTLS_STATE_WAIT_SERVERKEYEXCHANGE) {
3327 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3329 err = check_server_key_exchange_ecdh(ctx, peer, data, data_length);
3331 #endif /* DTLS_ECC */
3333 if (is_tls_psk_with_aes_128_ccm_8(peer->handshake_params->cipher)) {
3334 if (state != DTLS_STATE_WAIT_SERVERHELLODONE) {
3335 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3337 err = check_server_key_exchange_psk(ctx, peer, data, data_length);
3339 #endif /* DTLS_PSK */
3342 dtls_warn("error in check_server_key_exchange err: %i\n", err);
3345 peer->state = DTLS_STATE_WAIT_SERVERHELLODONE;
3346 /* update_hs_hash(peer, data, data_length); */
3350 case DTLS_HT_SERVER_HELLO_DONE:
3352 if (state != DTLS_STATE_WAIT_SERVERHELLODONE) {
3353 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3356 err = check_server_hellodone(ctx, peer, data, data_length);
3358 dtls_warn("error in check_server_hellodone err: %i\n", err);
3361 peer->state = DTLS_STATE_WAIT_CHANGECIPHERSPEC;
3362 /* update_hs_hash(peer, data, data_length); */
3366 case DTLS_HT_CERTIFICATE_REQUEST:
3368 if (state != DTLS_STATE_WAIT_SERVERHELLODONE) {
3369 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3372 err = check_certificate_request(ctx, peer, data, data_length);
3374 dtls_warn("error in check_certificate_request err: %i\n", err);
3380 case DTLS_HT_FINISHED:
3381 /* expect a Finished message from server */
3383 if (state != DTLS_STATE_WAIT_FINISHED) {
3384 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3387 err = check_finished(ctx, peer, data, data_length);
3389 dtls_warn("error in check_finished err: %i\n", err);
3392 if (role == DTLS_SERVER) {
3393 /* send ServerFinished */
3394 update_hs_hash(peer, data, data_length);
3396 /* send change cipher spec message and switch to new configuration */
3397 err = dtls_send_ccs(ctx, peer);
3399 dtls_warn("cannot send CCS message\n");
3403 dtls_security_params_switch(peer);
3405 err = dtls_send_finished(ctx, peer, PRF_LABEL(server), PRF_LABEL_SIZE(server));
3407 dtls_warn("sending server Finished failed\n");
3411 dtls_handshake_free(peer->handshake_params);
3412 peer->handshake_params = NULL;
3413 dtls_debug("Handshake complete\n");
3415 peer->state = DTLS_STATE_CONNECTED;
3417 /* return here to not increase the message receive counter */
3420 /************************************************************************
3422 ************************************************************************/
3424 case DTLS_HT_CLIENT_KEY_EXCHANGE:
3425 /* handle ClientHello, update msg and msglen and goto next if not finished */
3427 if (state != DTLS_STATE_WAIT_CLIENTKEYEXCHANGE) {
3428 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3431 err = check_client_keyexchange(ctx, peer->handshake_params, data, data_length);
3433 dtls_warn("error in check_client_keyexchange err: %i\n", err);
3436 update_hs_hash(peer, data, data_length);
3438 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(peer->handshake_params->cipher) &&
3439 is_ecdsa_client_auth_supported(ctx))
3440 peer->state = DTLS_STATE_WAIT_CERTIFICATEVERIFY; //ecdsa
3442 peer->state = DTLS_STATE_WAIT_CHANGECIPHERSPEC; //psk || ecdh_anon
3446 case DTLS_HT_CERTIFICATE_VERIFY:
3448 if (state != DTLS_STATE_WAIT_CERTIFICATEVERIFY) {
3449 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3452 err = check_client_certificate_verify(ctx, peer, data, data_length);
3454 dtls_warn("error in check_client_certificate_verify err: %i\n", err);
3458 update_hs_hash(peer, data, data_length);
3459 peer->state = DTLS_STATE_WAIT_CHANGECIPHERSPEC;
3461 #endif /* DTLS_ECC */
3463 case DTLS_HT_CLIENT_HELLO:
3465 if ((peer && state != DTLS_STATE_CONNECTED && state != DTLS_STATE_WAIT_CLIENTHELLO) ||
3466 (!peer && state != DTLS_STATE_WAIT_CLIENTHELLO)) {
3467 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3470 /* When no DTLS state exists for this peer, we only allow a
3471 Client Hello message with
3473 a) a valid cookie, or
3476 Anything else will be rejected. Fragementation is not allowed
3477 here as it would require peer state as well.
3479 err = dtls_verify_peer(ctx, peer, session, state, data, data_length);
3481 dtls_warn("error in dtls_verify_peer err: %i\n", err);
3486 dtls_debug("server hello verify was sent\n");
3490 /* At this point, we have a good relationship with this peer. This
3491 * state is left for re-negotiation of key material. */
3492 /* As per RFC 6347 - section 4.2.8 if this is an attempt to
3493 * rehandshake, we can delete the existing key material
3494 * as the client has demonstrated reachibility by completing
3495 * the cookie exchange */
3496 if (peer && state == DTLS_STATE_WAIT_CLIENTHELLO) {
3497 dtls_debug("removing the peer\n");
3498 #ifndef WITH_CONTIKI
3499 HASH_DEL_PEER(ctx->peers, peer);
3500 #else /* WITH_CONTIKI */
3501 list_remove(ctx->peers, peer);
3502 #endif /* WITH_CONTIKI */
3504 dtls_free_peer(peer);
3508 dtls_debug("creating new peer\n");
3509 dtls_security_parameters_t *security;
3511 /* msg contains a Client Hello with a valid cookie, so we can
3512 * safely create the server state machine and continue with
3514 peer = dtls_new_peer(session);
3516 dtls_alert("cannot create peer\n");
3517 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
3519 peer->role = DTLS_SERVER;
3521 /* Initialize record sequence number to 1 for new peers. The first
3522 * record with sequence number 0 is a stateless Hello Verify Request.
3524 security = dtls_security_params(peer);
3526 dtls_add_peer(ctx, peer);
3528 if (peer && !peer->handshake_params) {
3529 dtls_handshake_header_t *hs_header = DTLS_HANDSHAKE_HEADER(data);
3531 peer->handshake_params = dtls_handshake_new();
3532 if (!peer->handshake_params)
3533 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
3535 LIST_STRUCT_INIT(peer->handshake_params, reorder_queue);
3536 peer->handshake_params->hs_state.mseq_r = dtls_uint16_to_int(hs_header->message_seq);
3537 peer->handshake_params->hs_state.mseq_s = 1;
3540 clear_hs_hash(peer);
3542 /* First negotiation step: check for PSK
3544 * Note that we already have checked that msg is a Handshake
3545 * message containing a ClientHello. dtls_get_cipher() therefore
3546 * does not check again.
3548 err = dtls_update_parameters(ctx, peer, data, data_length);
3550 dtls_warn("error updating security parameters\n");
3554 /* update finish MAC */
3555 update_hs_hash(peer, data, data_length);
3557 err = dtls_send_server_hello_msgs(ctx, peer);
3561 if (is_tls_ecdhe_ecdsa_with_aes_128_ccm_8(peer->handshake_params->cipher) &&
3562 is_ecdsa_client_auth_supported(ctx))
3563 peer->state = DTLS_STATE_WAIT_CLIENTCERTIFICATE; //ecdhe
3565 peer->state = DTLS_STATE_WAIT_CLIENTKEYEXCHANGE; //psk, ecdh_anon
3567 /* after sending the ServerHelloDone, we expect the
3568 * ClientKeyExchange (possibly containing the PSK id),
3569 * followed by a ChangeCipherSpec and an encrypted Finished.
3574 case DTLS_HT_HELLO_REQUEST:
3576 if (state != DTLS_STATE_CONNECTED) {
3577 /* we should just ignore such packets when in handshake */
3581 if (peer && !peer->handshake_params) {
3582 peer->handshake_params = dtls_handshake_new();
3583 if (!peer->handshake_params)
3584 return dtls_alert_fatal_create(DTLS_ALERT_INTERNAL_ERROR);
3586 LIST_STRUCT_INIT(peer->handshake_params, reorder_queue);
3587 peer->handshake_params->hs_state.mseq_r = 0;
3588 peer->handshake_params->hs_state.mseq_s = 0;
3591 /* send ClientHello with empty Cookie */
3592 err = dtls_send_client_hello(ctx, peer, NULL, 0);
3594 dtls_warn("cannot send ClientHello\n");
3597 peer->state = DTLS_STATE_CLIENTHELLO;
3601 dtls_crit("unhandled message %d\n", data[0]);
3602 return dtls_alert_fatal_create(DTLS_ALERT_UNEXPECTED_MESSAGE);
3605 if (peer && peer->handshake_params && err >= 0) {
3606 peer->handshake_params->hs_state.mseq_r++;
3613 handle_handshake(dtls_context_t *ctx, dtls_peer_t *peer, session_t *session,
3614 const dtls_peer_type role, const dtls_state_t state,
3615 uint8 *data, size_t data_length)
3617 dtls_handshake_header_t *hs_header;
3620 if (data_length < DTLS_HS_LENGTH) {
3621 dtls_warn("handshake message too short\n");
3622 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
3624 hs_header = DTLS_HANDSHAKE_HEADER(data);
3626 dtls_debug("received handshake packet of type: %s (%i)\n",
3627 dtls_handshake_type_to_name(hs_header->msg_type), hs_header->msg_type);
3629 if (!peer || !peer->handshake_params) {
3630 /* This is the initial ClientHello */
3631 if (hs_header->msg_type != DTLS_HT_CLIENT_HELLO && !peer) {
3632 dtls_warn("If there is no peer only ClientHello is allowed\n");
3633 return dtls_alert_fatal_create(DTLS_ALERT_HANDSHAKE_FAILURE);
3636 /* This is a ClientHello or Hello Request send when doing TLS renegotiation */
3637 if (hs_header->msg_type == DTLS_HT_CLIENT_HELLO ||
3638 hs_header->msg_type == DTLS_HT_HELLO_REQUEST) {
3639 return handle_handshake_msg(ctx, peer, session, role, state, data,
3642 dtls_warn("ignore unexpected handshake message\n");
3647 if (dtls_uint16_to_int(hs_header->message_seq) < peer->handshake_params->hs_state.mseq_r) {
3648 dtls_warn("The message sequence number is too small, expected %i, got: %i\n",
3649 peer->handshake_params->hs_state.mseq_r, dtls_uint16_to_int(hs_header->message_seq));
3651 } else if (dtls_uint16_to_int(hs_header->message_seq) > peer->handshake_params->hs_state.mseq_r) {
3652 /* A packet in between is missing, buffer this packet. */
3655 /* TODO: only add packet that are not too new. */
3656 if (data_length > DTLS_MAX_BUF) {
3657 dtls_warn("the packet is too big to buffer for reoder\n");
3661 netq_t *node = netq_head(peer->handshake_params->reorder_queue);
3663 dtls_handshake_header_t *node_header = DTLS_HANDSHAKE_HEADER(node->data);
3664 if (dtls_uint16_to_int(node_header->message_seq) == dtls_uint16_to_int(hs_header->message_seq)) {
3665 dtls_warn("a packet with this sequence number is already stored\n");
3668 node = netq_next(node);
3671 n = netq_node_new(data_length);
3673 dtls_warn("no space in reoder buffer\n");
3678 n->length = data_length;
3679 memcpy(n->data, data, data_length);
3681 if (!netq_insert_node(peer->handshake_params->reorder_queue, n)) {
3682 dtls_warn("cannot add packet to reoder buffer\n");
3685 dtls_info("Added packet for reordering\n");
3687 } else if (dtls_uint16_to_int(hs_header->message_seq) == peer->handshake_params->hs_state.mseq_r) {
3688 /* Found the expected packet, use this and all the buffered packet */
3691 res = handle_handshake_msg(ctx, peer, session, role, state, data, data_length);
3695 /* We do not know in which order the packet are in the list just search the list for every packet. */
3696 while (next && peer->handshake_params) {
3698 netq_t *node = netq_head(peer->handshake_params->reorder_queue);
3700 dtls_handshake_header_t *node_header = DTLS_HANDSHAKE_HEADER(node->data);
3702 if (dtls_uint16_to_int(node_header->message_seq) == peer->handshake_params->hs_state.mseq_r) {
3703 netq_remove(peer->handshake_params->reorder_queue, node);
3705 res = handle_handshake_msg(ctx, peer, session, role, peer->state, node->data, node->length);
3712 node = netq_next(node);
3723 handle_ccs(dtls_context_t *ctx, dtls_peer_t *peer,
3724 uint8 *record_header, uint8 *data, size_t data_length)
3727 dtls_handshake_parameters_t *handshake = peer->handshake_params;
3729 /* A CCS message is handled after a KeyExchange message was
3730 * received from the client. When security parameters have been
3731 * updated successfully and a ChangeCipherSpec message was sent
3732 * by ourself, the security context is switched and the record
3733 * sequence number is reset. */
3735 if (!peer || peer->state != DTLS_STATE_WAIT_CHANGECIPHERSPEC) {
3736 dtls_warn("expected ChangeCipherSpec during handshake\n");
3740 if (data_length < 1 || data[0] != 1)
3741 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
3743 /* Just change the cipher when we are on the same epoch */
3744 if (peer->role == DTLS_SERVER) {
3745 err = calculate_key_block(ctx, handshake, peer,
3746 &peer->session, peer->role);
3752 peer->state = DTLS_STATE_WAIT_FINISHED;
3758 * Handles incoming Alert messages. This function returns \c 1 if the
3759 * connection should be closed and the peer is to be invalidated.
3762 handle_alert(dtls_context_t *ctx, dtls_peer_t *peer,
3763 uint8 *record_header, uint8 *data, size_t data_length) {
3764 int free_peer = 0; /* indicates whether to free peer */
3766 if (data_length < 2)
3767 return dtls_alert_fatal_create(DTLS_ALERT_DECODE_ERROR);
3769 dtls_info("** Alert: level %d, description %d\n", data[0], data[1]);
3772 dtls_warn("got an alert for an unknown peer, we probably already removed it, ignore it\n");
3776 /* The peer object is invalidated for FATAL alerts and close
3777 * notifies. This is done in two steps.: First, remove the object
3778 * from our list of peers. After that, the event handler callback is
3779 * invoked with the still existing peer object. Finally, the storage
3780 * used by peer is released.
3782 if (data[0] == DTLS_ALERT_LEVEL_FATAL || data[1] == DTLS_ALERT_CLOSE_NOTIFY) {
3783 dtls_alert("%d invalidate peer\n", data[1]);
3785 #ifndef WITH_CONTIKI
3786 HASH_DEL_PEER(ctx->peers, peer);
3787 #else /* WITH_CONTIKI */
3788 list_remove(ctx->peers, peer);
3791 PRINTF("removed peer [");
3792 PRINT6ADDR(&peer->session.addr);
3793 PRINTF("]:%d\n", uip_ntohs(peer->session.port));
3795 #endif /* WITH_CONTIKI */
3801 (void)CALL(ctx, event, &peer->session,
3802 (dtls_alert_level_t)data[0], (unsigned short)data[1]);
3804 case DTLS_ALERT_CLOSE_NOTIFY:
3805 /* If state is DTLS_STATE_CLOSING, we have already sent a
3806 * close_notify so, do not send that again. */
3807 if (peer->state != DTLS_STATE_CLOSING) {
3808 peer->state = DTLS_STATE_CLOSING;
3809 dtls_send_alert(ctx, peer, DTLS_ALERT_LEVEL_FATAL, DTLS_ALERT_CLOSE_NOTIFY);
3811 peer->state = DTLS_STATE_CLOSED;
3818 dtls_stop_retransmission(ctx, peer);
3819 dtls_destroy_peer(ctx, peer, 0);
3825 static int dtls_alert_send_from_err(dtls_context_t *ctx, dtls_peer_t *peer,
3826 session_t *session, int err)
3831 if (err < -(1 << 8) && err > -(3 << 8)) {
3832 level = ((-err) & 0xff00) >> 8;
3833 desc = (-err) & 0xff;
3835 peer = dtls_get_peer(ctx, session);
3838 peer->state = DTLS_STATE_CLOSING;
3839 return dtls_send_alert(ctx, peer, level, desc);
3841 } else if (err == -1) {
3843 peer = dtls_get_peer(ctx, session);
3846 peer->state = DTLS_STATE_CLOSING;
3847 return dtls_send_alert(ctx, peer, DTLS_ALERT_LEVEL_FATAL, DTLS_ALERT_INTERNAL_ERROR);
3854 * Handles incoming data as DTLS message from given peer.
3857 dtls_handle_message(dtls_context_t *ctx,
3859 uint8 *msg, int msglen) {
3860 dtls_peer_t *peer = NULL;
3861 unsigned int rlen; /* record length */
3862 uint8 *data; /* (decrypted) payload */
3863 int data_length; /* length of decrypted payload
3864 (without MAC and padding) */
3867 /* check if we have DTLS state for addr/port/ifindex */
3868 peer = dtls_get_peer(ctx, session);
3871 dtls_debug("dtls_handle_message: PEER NOT FOUND\n");
3872 dtls_dsrv_log_addr(DTLS_LOG_DEBUG, "peer addr", session);
3874 dtls_debug("dtls_handle_message: FOUND PEER\n");
3877 while ((rlen = is_record(msg,msglen))) {
3878 dtls_peer_type role;
3881 dtls_debug("got packet %d (%d bytes)\n", msg[0], rlen);
3883 data_length = decrypt_verify(peer, msg, rlen, &data);
3884 if (data_length < 0) {
3885 if (hs_attempt_with_existing_peer(msg, rlen, peer)) {
3886 data = msg + DTLS_RH_LENGTH;
3887 data_length = rlen - DTLS_RH_LENGTH;
3888 state = DTLS_STATE_WAIT_CLIENTHELLO;
3891 int err = dtls_alert_fatal_create(DTLS_ALERT_DECRYPT_ERROR);
3892 dtls_info("decrypt_verify() failed\n");
3893 if (peer->state < DTLS_STATE_CONNECTED) {
3894 dtls_alert_send_from_err(ctx, peer, &peer->session, err);
3895 peer->state = DTLS_STATE_CLOSED;
3896 /* dtls_stop_retransmission(ctx, peer); */
3897 dtls_destroy_peer(ctx, peer, 1);
3903 state = peer->state;
3906 /* is_record() ensures that msg contains at least a record header */
3907 data = msg + DTLS_RH_LENGTH;
3908 data_length = rlen - DTLS_RH_LENGTH;
3909 state = DTLS_STATE_WAIT_CLIENTHELLO;
3913 dtls_debug_hexdump("receive header", msg, sizeof(dtls_record_header_t));
3914 dtls_debug_hexdump("receive unencrypted", data, data_length);
3916 /* Handle received record according to the first byte of the
3917 * message, i.e. the subprotocol. We currently do not support
3918 * combining multiple fragments of one type into a single
3923 case DTLS_CT_CHANGE_CIPHER_SPEC:
3925 dtls_stop_retransmission(ctx, peer);
3927 err = handle_ccs(ctx, peer, msg, data, data_length);
3929 dtls_warn("error while handling ChangeCipherSpec message\n");
3930 dtls_alert_send_from_err(ctx, peer, session, err);
3932 /* invalidate peer */
3933 dtls_destroy_peer(ctx, peer, 1);
3942 dtls_stop_retransmission(ctx, peer);
3944 err = handle_alert(ctx, peer, msg, data, data_length);
3945 if (err < 0 || err == 1) {
3946 dtls_warn("received alert, peer has been invalidated\n");
3947 /* handle alert has invalidated peer */
3949 return err < 0 ?err:-1;
3953 case DTLS_CT_HANDSHAKE:
3954 /* Handshake messages other than Finish must use the current
3955 * epoch, Finish has epoch + 1. */
3958 uint16_t expected_epoch = dtls_security_params(peer)->epoch;
3959 uint16_t msg_epoch =
3960 dtls_uint16_to_int(DTLS_RECORD_HEADER(msg)->epoch);
3962 /* The new security parameters must be used for all messages
3963 * that are sent after the ChangeCipherSpec message. This
3964 * means that the client's Finished message uses epoch + 1
3965 * while the server is still in the old epoch.
3967 if (role == DTLS_SERVER && state == DTLS_STATE_WAIT_FINISHED) {
3971 if (expected_epoch != msg_epoch) {
3972 if (hs_attempt_with_existing_peer(msg, rlen, peer)) {
3973 state = DTLS_STATE_WAIT_CLIENTHELLO;
3976 dtls_warn("Wrong epoch, expected %i, got: %i\n",
3977 expected_epoch, msg_epoch);
3983 err = handle_handshake(ctx, peer, session, role, state, data, data_length);
3985 dtls_warn("error while handling handshake packet\n");
3986 dtls_alert_send_from_err(ctx, peer, session, err);
3989 if (peer && peer->state == DTLS_STATE_CONNECTED) {
3990 /* stop retransmissions */
3991 dtls_stop_retransmission(ctx, peer);
3992 CALL(ctx, event, &peer->session, 0, DTLS_EVENT_CONNECTED);
3996 case DTLS_CT_APPLICATION_DATA:
3997 dtls_info("** application data:\n");
3999 dtls_warn("no peer available, send an alert\n");
4000 // TODO: should we send a alert here?
4003 dtls_stop_retransmission(ctx, peer);
4004 CALL(ctx, read, &peer->session, data, data_length);
4007 dtls_info("dropped unknown message of type %d\n",msg[0]);
4010 /* advance msg by length of ciphertext */
4019 dtls_new_context(void *app_data) {
4022 #ifndef WITH_CONTIKI
4023 FILE *urandom = fopen("/dev/urandom", "r");
4024 unsigned char buf[sizeof(unsigned long)];
4025 #endif /* WITH_CONTIKI */
4029 /* FIXME: need something better to init PRNG here */
4030 dtls_prng_init(now);
4031 #else /* WITH_CONTIKI */
4033 dtls_emerg("cannot initialize PRNG\n");
4037 if (fread(buf, 1, sizeof(buf), urandom) != sizeof(buf)) {
4038 dtls_emerg("cannot initialize PRNG\n");
4043 dtls_prng_init((unsigned long)*buf);
4044 #endif /* WITH_CONTIKI */
4046 c = malloc_context();
4050 memset(c, 0, sizeof(dtls_context_t));
4053 LIST_STRUCT_INIT(c, sendqueue);
4056 LIST_STRUCT_INIT(c, peers);
4057 /* LIST_STRUCT_INIT(c, key_store); */
4059 process_start(&dtls_retransmit_process, (char *)c);
4060 PROCESS_CONTEXT_BEGIN(&dtls_retransmit_process);
4061 /* the retransmit timer must be initialized to some large value */
4062 etimer_set(&c->retransmit_timer, 0xFFFF);
4063 PROCESS_CONTEXT_END(&coap_retransmit_process);
4064 #endif /* WITH_CONTIKI */
4066 if (dtls_prng(c->cookie_secret, DTLS_COOKIE_SECRET_LENGTH))
4067 c->cookie_secret_age = now;
4074 dtls_alert("cannot create DTLS context\n");
4076 dtls_free_context(c);
4081 dtls_free_context(dtls_context_t *ctx) {
4088 #ifndef WITH_CONTIKI
4092 HASH_ITER(hh, ctx->peers, p, tmp) {
4093 dtls_destroy_peer(ctx, p, 1);
4096 #else /* WITH_CONTIKI */
4097 for (p = list_head(ctx->peers); p; p = list_item_next(p))
4098 dtls_destroy_peer(ctx, p, 1);
4099 #endif /* WITH_CONTIKI */
4105 dtls_connect_peer(dtls_context_t *ctx, dtls_peer_t *peer) {
4112 /* check if the same peer is already in our list */
4113 if (peer == dtls_get_peer(ctx, &peer->session)) {
4114 dtls_debug("found peer, try to re-connect\n");
4115 return dtls_renegotiate(ctx, &peer->session);
4118 /* set local peer role to client, remote is server */
4119 peer->role = DTLS_CLIENT;
4121 dtls_add_peer(ctx, peer);
4123 /* send ClientHello with empty Cookie */
4124 peer->handshake_params = dtls_handshake_new();
4125 if (!peer->handshake_params)
4128 peer->handshake_params->hs_state.mseq_r = 0;
4129 peer->handshake_params->hs_state.mseq_s = 0;
4130 LIST_STRUCT_INIT(peer->handshake_params, reorder_queue);
4131 res = dtls_send_client_hello(ctx, peer, NULL, 0);
4133 dtls_warn("cannot send ClientHello\n");
4135 peer->state = DTLS_STATE_CLIENTHELLO;
4141 dtls_connect(dtls_context_t *ctx, const session_t *dst) {
4145 peer = dtls_get_peer(ctx, dst);
4148 peer = dtls_new_peer(dst);
4151 dtls_crit("cannot create new peer\n");
4155 res = dtls_connect_peer(ctx, peer);
4157 /* Invoke event callback to indicate connection attempt or
4158 * re-negotiation. */
4160 CALL(ctx, event, &peer->session, 0, DTLS_EVENT_CONNECT);
4161 } else if (res == 0) {
4162 CALL(ctx, event, &peer->session, 0, DTLS_EVENT_RENEGOTIATE);
4169 dtls_retransmit(dtls_context_t *context, netq_t *node) {
4170 if (!context || !node)
4173 /* re-initialize timeout when maximum number of retransmissions are not reached yet */
4174 if (node->retransmit_cnt < DTLS_DEFAULT_MAX_RETRANSMIT) {
4175 unsigned char sendbuf[DTLS_MAX_BUF];
4176 size_t len = sizeof(sendbuf);
4178 unsigned char *data = node->data;
4179 size_t length = node->length;
4181 dtls_security_parameters_t *security = dtls_security_params_epoch(node->peer, node->epoch);
4184 node->retransmit_cnt++;
4185 node->t = now + (node->timeout << node->retransmit_cnt);
4186 netq_insert_node(context->sendqueue, node);
4188 if (node->type == DTLS_CT_HANDSHAKE) {
4189 dtls_handshake_header_t *hs_header = DTLS_HANDSHAKE_HEADER(data);
4191 dtls_debug("** retransmit handshake packet of type: %s (%i)\n",
4192 dtls_handshake_type_to_name(hs_header->msg_type), hs_header->msg_type);
4194 dtls_debug("** retransmit packet\n");
4197 err = dtls_prepare_record(node->peer, security, node->type, &data, &length,
4200 dtls_warn("can not retransmit packet, err: %i\n", err);
4203 dtls_debug_hexdump("retransmit header", sendbuf,
4204 sizeof(dtls_record_header_t));
4205 dtls_debug_hexdump("retransmit unencrypted", node->data, node->length);
4207 (void)CALL(context, write, &node->peer->session, sendbuf, len);
4211 /* no more retransmissions, remove node from system */
4213 dtls_debug("** removed transaction\n");
4215 /* And finally delete the node */
4216 netq_node_free(node);
4220 dtls_stop_retransmission(dtls_context_t *context, dtls_peer_t *peer) {
4222 node = list_head(context->sendqueue);
4225 if (dtls_session_equals(&node->peer->session, &peer->session)) {
4227 node = list_item_next(node);
4228 list_remove(context->sendqueue, tmp);
4229 netq_node_free(tmp);
4231 node = list_item_next(node);
4236 dtls_check_retransmit(dtls_context_t *context, clock_time_t *next) {
4238 netq_t *node = netq_head(context->sendqueue);
4241 while (node && node->t <= now) {
4242 netq_pop_first(context->sendqueue);
4243 dtls_retransmit(context, node);
4244 node = netq_head(context->sendqueue);
4252 dtls_prf_with_current_keyblock(dtls_context_t *ctx, session_t *session,
4253 const uint8_t* label, const uint32_t labellen,
4254 const uint8_t* random1, const uint32_t random1len,
4255 const uint8_t* random2, const uint32_t random2len,
4256 uint8_t* buf, const uint32_t buflen) {
4257 dtls_peer_t *peer = NULL;
4258 dtls_security_parameters_t *security = NULL;
4261 if(!ctx || !session || !label || !buf || labellen == 0 || buflen == 0) {
4262 dtls_warn("dtls_prf_with_current_keyblock(): invalid parameter\n");
4266 peer = dtls_get_peer(ctx, session);
4268 dtls_warn("dtls_prf_with_current_keyblock(): cannot find peer\n");
4272 security = dtls_security_params(peer);
4274 dtls_crit("dtls_prf_with_current_keyblock(): peer has empty security parameters\n");
4278 /* note that keysize should never be zero as bad things will happen */
4279 keysize = dtls_kb_size(security, peer->role);
4280 assert(keysize > 0);
4282 return dtls_prf(security->key_block, keysize,
4284 random1, random1len,
4285 random2, random2len,
4290 /*---------------------------------------------------------------------------*/
4291 /* message retransmission */
4292 /*---------------------------------------------------------------------------*/
4293 PROCESS_THREAD(dtls_retransmit_process, ev, data)
4300 dtls_debug("Started DTLS retransmit process\r\n");
4304 if (ev == PROCESS_EVENT_TIMER) {
4305 if (etimer_expired(&the_dtls_context.retransmit_timer)) {
4307 node = list_head(the_dtls_context.sendqueue);
4310 if (node && node->t <= now) {
4311 dtls_retransmit(&the_dtls_context, list_pop(the_dtls_context.sendqueue));
4312 node = list_head(the_dtls_context.sendqueue);
4315 /* need to set timer to some value even if no nextpdu is available */
4317 etimer_set(&the_dtls_context.retransmit_timer,
4318 node->t <= now ? 1 : node->t - now);
4320 etimer_set(&the_dtls_context.retransmit_timer, 0xFFFF);
4328 #endif /* WITH_CONTIKI */