/* * DTLS implementation written by Nagendra Modadugu * (nagendra@cs.stanford.edu) for the OpenSSL project 2005. */ /* ==================================================================== * Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. All advertising materials mentioning features or use of this * software must display the following acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" * * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to * endorse or promote products derived from this software without * prior written permission. For written permission, please contact * openssl-core@openssl.org. * * 5. Products derived from this software may not be called "OpenSSL" * nor may "OpenSSL" appear in their names without prior written * permission of the OpenSSL Project. * * 6. Redistributions of any form whatsoever must retain the following * acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit (http://www.openssl.org/)" * * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED * OF THE POSSIBILITY OF SUCH DAMAGE. * ==================================================================== * * This product includes cryptographic software written by Eric Young * (eay@cryptsoft.com). This product includes software written by Tim * Hudson (tjh@cryptsoft.com). * */ /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. * * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to. The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code. The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). * * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * "This product includes cryptographic software written by * Eric Young (eay@cryptsoft.com)" * The word 'cryptographic' can be left out if the rouines from the library * being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from * the apps directory (application code) you must include an acknowledgement: * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" * * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */ #include #include #include #include #include #include #include #include #include #include #include "internal.h" /* TODO(davidben): 28 comes from the size of IP + UDP header. Is this reasonable * for these values? Notably, why is kMinMTU a function of the transport * protocol's overhead rather than, say, what's needed to hold a minimally-sized * handshake fragment plus protocol overhead. */ /* kMinMTU is the minimum acceptable MTU value. */ static const unsigned int kMinMTU = 256 - 28; /* kDefaultMTU is the default MTU value to use if neither the user nor * the underlying BIO supplies one. */ static const unsigned int kDefaultMTU = 1500 - 28; /* kMaxHandshakeBuffer is the maximum number of handshake messages ahead of the * current one to buffer. */ static const unsigned int kHandshakeBufferSize = 10; static hm_fragment *dtls1_hm_fragment_new(size_t frag_len, int reassembly) { hm_fragment *frag = OPENSSL_malloc(sizeof(hm_fragment)); if (frag == NULL) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); return NULL; } memset(frag, 0, sizeof(hm_fragment)); /* If the handshake message is empty, |frag->fragment| and |frag->reassembly| * are NULL. */ if (frag_len > 0) { frag->fragment = OPENSSL_malloc(frag_len); if (frag->fragment == NULL) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); goto err; } if (reassembly) { /* Initialize reassembly bitmask. */ if (frag_len + 7 < frag_len) { OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); goto err; } size_t bitmask_len = (frag_len + 7) / 8; frag->reassembly = OPENSSL_malloc(bitmask_len); if (frag->reassembly == NULL) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); goto err; } memset(frag->reassembly, 0, bitmask_len); } } return frag; err: dtls1_hm_fragment_free(frag); return NULL; } void dtls1_hm_fragment_free(hm_fragment *frag) { if (frag == NULL) { return; } OPENSSL_free(frag->fragment); OPENSSL_free(frag->reassembly); OPENSSL_free(frag); } #if !defined(inline) #define inline __inline #endif /* bit_range returns a |uint8_t| with bits |start|, inclusive, to |end|, * exclusive, set. */ static inline uint8_t bit_range(size_t start, size_t end) { return (uint8_t)(~((1u << start) - 1) & ((1u << end) - 1)); } /* dtls1_hm_fragment_mark marks bytes |start|, inclusive, to |end|, exclusive, * as received in |frag|. If |frag| becomes complete, it clears * |frag->reassembly|. The range must be within the bounds of |frag|'s message * and |frag->reassembly| must not be NULL. */ static void dtls1_hm_fragment_mark(hm_fragment *frag, size_t start, size_t end) { size_t i; size_t msg_len = frag->msg_header.msg_len; if (frag->reassembly == NULL || start > end || end > msg_len) { assert(0); return; } /* A zero-length message will never have a pending reassembly. */ assert(msg_len > 0); if ((start >> 3) == (end >> 3)) { frag->reassembly[start >> 3] |= bit_range(start & 7, end & 7); } else { frag->reassembly[start >> 3] |= bit_range(start & 7, 8); for (i = (start >> 3) + 1; i < (end >> 3); i++) { frag->reassembly[i] = 0xff; } if ((end & 7) != 0) { frag->reassembly[end >> 3] |= bit_range(0, end & 7); } } /* Check if the fragment is complete. */ for (i = 0; i < (msg_len >> 3); i++) { if (frag->reassembly[i] != 0xff) { return; } } if ((msg_len & 7) != 0 && frag->reassembly[msg_len >> 3] != bit_range(0, msg_len & 7)) { return; } OPENSSL_free(frag->reassembly); frag->reassembly = NULL; } static void dtls1_update_mtu(SSL *ssl) { /* TODO(davidben): What is this code doing and do we need it? */ if (ssl->d1->mtu < dtls1_min_mtu() && !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) { long mtu = BIO_ctrl(ssl->wbio, BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL); if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) { ssl->d1->mtu = (unsigned)mtu; } else { ssl->d1->mtu = kDefaultMTU; BIO_ctrl(ssl->wbio, BIO_CTRL_DGRAM_SET_MTU, ssl->d1->mtu, NULL); } } /* The MTU should be above the minimum now. */ assert(ssl->d1->mtu >= dtls1_min_mtu()); } /* dtls1_max_record_size returns the maximum record body length that may be * written without exceeding the MTU. It accounts for any buffering installed on * the write BIO. If no record may be written, it returns zero. */ static size_t dtls1_max_record_size(SSL *ssl) { size_t ret = ssl->d1->mtu; size_t overhead = ssl_max_seal_overhead(ssl); if (ret <= overhead) { return 0; } ret -= overhead; size_t pending = BIO_wpending(ssl->wbio); if (ret <= pending) { return 0; } ret -= pending; return ret; } static int dtls1_write_change_cipher_spec(SSL *ssl, enum dtls1_use_epoch_t use_epoch) { dtls1_update_mtu(ssl); /* During the handshake, wbio is buffered to pack messages together. Flush the * buffer if the ChangeCipherSpec would not fit in a packet. */ if (dtls1_max_record_size(ssl) == 0) { int ret = BIO_flush(ssl->wbio); if (ret <= 0) { ssl->rwstate = SSL_WRITING; return ret; } } static const uint8_t kChangeCipherSpec[1] = {SSL3_MT_CCS}; int ret = dtls1_write_record(ssl, SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec, sizeof(kChangeCipherSpec), use_epoch); if (ret <= 0) { return ret; } ssl_do_msg_callback(ssl, 1 /* write */, ssl->version, SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec, sizeof(kChangeCipherSpec)); return 1; } int dtls1_do_handshake_write(SSL *ssl, size_t *out_offset, const uint8_t *in, size_t offset, size_t len, enum dtls1_use_epoch_t use_epoch) { dtls1_update_mtu(ssl); int ret = -1; CBB cbb; CBB_zero(&cbb); /* Allocate a temporary buffer to hold the message fragments to avoid * clobbering the message. */ uint8_t *buf = OPENSSL_malloc(ssl->d1->mtu); if (buf == NULL) { goto err; } /* Although it may be sent as multiple fragments, a DTLS message must be sent * serialized as a single fragment for purposes of |ssl_do_msg_callback| and * the handshake hash. */ CBS cbs, body; struct hm_header_st hdr; CBS_init(&cbs, in, len); if (!dtls1_parse_fragment(&cbs, &hdr, &body) || hdr.frag_off != 0 || hdr.frag_len != CBS_len(&body) || hdr.msg_len != CBS_len(&body) || !CBS_skip(&body, offset) || CBS_len(&cbs) != 0) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); goto err; } do { /* During the handshake, wbio is buffered to pack messages together. Flush * the buffer if there isn't enough room to make progress. */ if (dtls1_max_record_size(ssl) < DTLS1_HM_HEADER_LENGTH + 1) { int flush_ret = BIO_flush(ssl->wbio); if (flush_ret <= 0) { ssl->rwstate = SSL_WRITING; ret = flush_ret; goto err; } assert(BIO_wpending(ssl->wbio) == 0); } size_t todo = dtls1_max_record_size(ssl); if (todo < DTLS1_HM_HEADER_LENGTH + 1) { /* To make forward progress, the MTU must, at minimum, fit the handshake * header and one byte of handshake body. */ OPENSSL_PUT_ERROR(SSL, SSL_R_MTU_TOO_SMALL); goto err; } todo -= DTLS1_HM_HEADER_LENGTH; if (todo > CBS_len(&body)) { todo = CBS_len(&body); } if (todo >= (1u << 24)) { todo = (1u << 24) - 1; } size_t buf_len; if (!CBB_init_fixed(&cbb, buf, ssl->d1->mtu) || !CBB_add_u8(&cbb, hdr.type) || !CBB_add_u24(&cbb, hdr.msg_len) || !CBB_add_u16(&cbb, hdr.seq) || !CBB_add_u24(&cbb, offset) || !CBB_add_u24(&cbb, todo) || !CBB_add_bytes(&cbb, CBS_data(&body), todo) || !CBB_finish(&cbb, NULL, &buf_len)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); goto err; } int write_ret = dtls1_write_record(ssl, SSL3_RT_HANDSHAKE, buf, buf_len, use_epoch); if (write_ret <= 0) { ret = write_ret; goto err; } if (!CBS_skip(&body, todo)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); goto err; } offset += todo; } while (CBS_len(&body) != 0); ssl_do_msg_callback(ssl, 1 /* write */, ssl->version, SSL3_RT_HANDSHAKE, in, len); ret = 1; err: *out_offset = offset; CBB_cleanup(&cbb); OPENSSL_free(buf); return ret; } /* dtls1_is_next_message_complete returns one if the next handshake message is * complete and zero otherwise. */ static int dtls1_is_next_message_complete(SSL *ssl) { pitem *item = pqueue_peek(ssl->d1->buffered_messages); if (item == NULL) { return 0; } hm_fragment *frag = (hm_fragment *)item->data; assert(ssl->d1->handshake_read_seq <= frag->msg_header.seq); return ssl->d1->handshake_read_seq == frag->msg_header.seq && frag->reassembly == NULL; } /* dtls1_get_buffered_message returns the buffered message corresponding to * |msg_hdr|. If none exists, it creates a new one and inserts it in the * queue. Otherwise, it checks |msg_hdr| is consistent with the existing one. It * returns NULL on failure. The caller does not take ownership of the result. */ static hm_fragment *dtls1_get_buffered_message( SSL *ssl, const struct hm_header_st *msg_hdr) { uint8_t seq64be[8]; memset(seq64be, 0, sizeof(seq64be)); seq64be[6] = (uint8_t)(msg_hdr->seq >> 8); seq64be[7] = (uint8_t)msg_hdr->seq; pitem *item = pqueue_find(ssl->d1->buffered_messages, seq64be); hm_fragment *frag; if (item == NULL) { /* This is the first fragment from this message. */ frag = dtls1_hm_fragment_new(msg_hdr->msg_len, 1 /* reassembly buffer needed */); if (frag == NULL) { return NULL; } memcpy(&frag->msg_header, msg_hdr, sizeof(*msg_hdr)); item = pitem_new(seq64be, frag); if (item == NULL) { dtls1_hm_fragment_free(frag); return NULL; } item = pqueue_insert(ssl->d1->buffered_messages, item); /* |pqueue_insert| fails iff a duplicate item is inserted, but |item| cannot * be a duplicate. */ assert(item != NULL); } else { frag = item->data; assert(frag->msg_header.seq == msg_hdr->seq); if (frag->msg_header.type != msg_hdr->type || frag->msg_header.msg_len != msg_hdr->msg_len) { /* The new fragment must be compatible with the previous fragments from * this message. */ OPENSSL_PUT_ERROR(SSL, SSL_R_FRAGMENT_MISMATCH); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return NULL; } } return frag; } /* dtls1_process_handshake_record reads a handshake record and processes it. It * returns one if the record was successfully processed and 0 or -1 on error. */ static int dtls1_process_handshake_record(SSL *ssl) { SSL3_RECORD *rr = &ssl->s3->rrec; start: if (rr->length == 0) { int ret = dtls1_get_record(ssl); if (ret <= 0) { return ret; } } /* Cross-epoch records are discarded, but we may receive out-of-order * application data between ChangeCipherSpec and Finished or a ChangeCipherSpec * before the appropriate point in the handshake. Those must be silently * discarded. * * However, only allow the out-of-order records in the correct epoch. * Application data must come in the encrypted epoch, and ChangeCipherSpec in * the unencrypted epoch (we never renegotiate). Other cases fall through and * fail with a fatal error. */ if ((rr->type == SSL3_RT_APPLICATION_DATA && ssl->s3->aead_read_ctx != NULL) || (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC && ssl->s3->aead_read_ctx == NULL)) { rr->length = 0; goto start; } if (rr->type != SSL3_RT_HANDSHAKE) { ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE); OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); return -1; } CBS cbs; CBS_init(&cbs, rr->data, rr->length); while (CBS_len(&cbs) > 0) { /* Read a handshake fragment. */ struct hm_header_st msg_hdr; CBS body; if (!dtls1_parse_fragment(&cbs, &msg_hdr, &body)) { OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_HANDSHAKE_RECORD); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return -1; } const size_t frag_off = msg_hdr.frag_off; const size_t frag_len = msg_hdr.frag_len; const size_t msg_len = msg_hdr.msg_len; if (frag_off > msg_len || frag_off + frag_len < frag_off || frag_off + frag_len > msg_len || msg_len > ssl_max_handshake_message_len(ssl)) { OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESSIVE_MESSAGE_SIZE); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return -1; } if (msg_hdr.seq < ssl->d1->handshake_read_seq || msg_hdr.seq > (unsigned)ssl->d1->handshake_read_seq + kHandshakeBufferSize) { /* Ignore fragments from the past, or ones too far in the future. */ continue; } hm_fragment *frag = dtls1_get_buffered_message(ssl, &msg_hdr); if (frag == NULL) { return -1; } assert(frag->msg_header.msg_len == msg_len); if (frag->reassembly == NULL) { /* The message is already assembled. */ continue; } assert(msg_len > 0); /* Copy the body into the fragment. */ memcpy(frag->fragment + frag_off, CBS_data(&body), CBS_len(&body)); dtls1_hm_fragment_mark(frag, frag_off, frag_off + frag_len); } rr->length = 0; ssl_read_buffer_discard(ssl); return 1; } /* dtls1_get_message reads a handshake message of message type |msg_type| (any * if |msg_type| == -1). Read an entire handshake message. Handshake messages * arrive in fragments. */ long dtls1_get_message(SSL *ssl, int msg_type, enum ssl_hash_message_t hash_message, int *ok) { pitem *item = NULL; hm_fragment *frag = NULL; int al; /* s3->tmp is used to store messages that are unexpected, caused * by the absence of an optional handshake message */ if (ssl->s3->tmp.reuse_message) { /* A ssl_dont_hash_message call cannot be combined with reuse_message; the * ssl_dont_hash_message would have to have been applied to the previous * call. */ assert(hash_message == ssl_hash_message); ssl->s3->tmp.reuse_message = 0; if (msg_type >= 0 && ssl->s3->tmp.message_type != msg_type) { al = SSL_AD_UNEXPECTED_MESSAGE; OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE); goto f_err; } *ok = 1; assert(ssl->init_buf->length >= DTLS1_HM_HEADER_LENGTH); ssl->init_msg = (uint8_t *)ssl->init_buf->data + DTLS1_HM_HEADER_LENGTH; ssl->init_num = (int)ssl->init_buf->length - DTLS1_HM_HEADER_LENGTH; return ssl->init_num; } /* Process handshake records until the next message is ready. */ while (!dtls1_is_next_message_complete(ssl)) { int ret = dtls1_process_handshake_record(ssl); if (ret <= 0) { *ok = 0; return ret; } } /* Read out the next complete handshake message. */ item = pqueue_pop(ssl->d1->buffered_messages); assert(item != NULL); frag = (hm_fragment *)item->data; assert(ssl->d1->handshake_read_seq == frag->msg_header.seq); assert(frag->reassembly == NULL); /* Reconstruct the assembled message. */ CBB cbb; CBB_zero(&cbb); if (!BUF_MEM_reserve(ssl->init_buf, (size_t)frag->msg_header.msg_len + DTLS1_HM_HEADER_LENGTH) || !CBB_init_fixed(&cbb, (uint8_t *)ssl->init_buf->data, ssl->init_buf->max) || !CBB_add_u8(&cbb, frag->msg_header.type) || !CBB_add_u24(&cbb, frag->msg_header.msg_len) || !CBB_add_u16(&cbb, frag->msg_header.seq) || !CBB_add_u24(&cbb, 0 /* frag_off */) || !CBB_add_u24(&cbb, frag->msg_header.msg_len) || !CBB_add_bytes(&cbb, frag->fragment, frag->msg_header.msg_len) || !CBB_finish(&cbb, NULL, &ssl->init_buf->length)) { CBB_cleanup(&cbb); OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); goto err; } assert(ssl->init_buf->length == (size_t)frag->msg_header.msg_len + DTLS1_HM_HEADER_LENGTH); ssl->d1->handshake_read_seq++; /* TODO(davidben): This function has a lot of implicit outputs. Simplify the * |ssl_get_message| API. */ ssl->s3->tmp.message_type = frag->msg_header.type; ssl->init_msg = (uint8_t *)ssl->init_buf->data + DTLS1_HM_HEADER_LENGTH; ssl->init_num = frag->msg_header.msg_len; if (msg_type >= 0 && ssl->s3->tmp.message_type != msg_type) { al = SSL_AD_UNEXPECTED_MESSAGE; OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE); goto f_err; } if (hash_message == ssl_hash_message && !ssl3_hash_current_message(ssl)) { goto err; } ssl_do_msg_callback(ssl, 0 /* read */, ssl->version, SSL3_RT_HANDSHAKE, ssl->init_buf->data, ssl->init_num + DTLS1_HM_HEADER_LENGTH); pitem_free(item); dtls1_hm_fragment_free(frag); *ok = 1; return ssl->init_num; f_err: ssl3_send_alert(ssl, SSL3_AL_FATAL, al); err: pitem_free(item); dtls1_hm_fragment_free(frag); *ok = 0; return -1; } static uint16_t dtls1_get_queue_priority(uint16_t seq, int is_ccs) { assert(seq * 2 >= seq); /* The index of the retransmission queue actually is the message sequence * number, since the queue only contains messages of a single handshake. * However, the ChangeCipherSpec has no message sequence number and so using * only the sequence will result in the CCS and Finished having the same * index. To prevent this, the sequence number is multiplied by 2. In case of * a CCS 1 is subtracted. This does not only differ CSS and Finished, it also * maintains the order of the index (important for priority queues) and fits * in the unsigned short variable. */ return seq * 2 - is_ccs; } static int dtls1_retransmit_message(SSL *ssl, hm_fragment *frag) { /* DTLS renegotiation is unsupported, so only epochs 0 (NULL cipher) and 1 * (negotiated cipher) exist. */ assert(ssl->d1->w_epoch == 0 || ssl->d1->w_epoch == 1); assert(frag->msg_header.epoch <= ssl->d1->w_epoch); enum dtls1_use_epoch_t use_epoch = dtls1_use_current_epoch; if (ssl->d1->w_epoch == 1 && frag->msg_header.epoch == 0) { use_epoch = dtls1_use_previous_epoch; } /* TODO(davidben): This cannot handle non-blocking writes. */ int ret; if (frag->msg_header.is_ccs) { ret = dtls1_write_change_cipher_spec(ssl, use_epoch); } else { size_t offset = 0; ret = dtls1_do_handshake_write( ssl, &offset, frag->fragment, offset, frag->msg_header.msg_len + DTLS1_HM_HEADER_LENGTH, use_epoch); } return ret; } int dtls1_retransmit_buffered_messages(SSL *ssl) { /* Ensure we are packing handshake messages. */ const int was_buffered = ssl_is_wbio_buffered(ssl); assert(was_buffered == SSL_in_init(ssl)); if (!was_buffered && !ssl_init_wbio_buffer(ssl)) { return -1; } assert(ssl_is_wbio_buffered(ssl)); int ret = -1; piterator iter = pqueue_iterator(ssl->d1->sent_messages); pitem *item; for (item = pqueue_next(&iter); item != NULL; item = pqueue_next(&iter)) { hm_fragment *frag = (hm_fragment *)item->data; if (dtls1_retransmit_message(ssl, frag) <= 0) { goto err; } } ret = BIO_flush(ssl->wbio); if (ret <= 0) { ssl->rwstate = SSL_WRITING; goto err; } err: if (!was_buffered) { ssl_free_wbio_buffer(ssl); } return ret; } /* dtls1_buffer_change_cipher_spec adds a ChangeCipherSpec to the current * handshake flight, ordered just before the handshake message numbered * |seq|. */ static int dtls1_buffer_change_cipher_spec(SSL *ssl, uint16_t seq) { hm_fragment *frag = dtls1_hm_fragment_new(0 /* frag_len */, 0 /* no reassembly */); if (frag == NULL) { return 0; } frag->msg_header.is_ccs = 1; frag->msg_header.epoch = ssl->d1->w_epoch; uint16_t priority = dtls1_get_queue_priority(seq, 1 /* is_ccs */); uint8_t seq64be[8]; memset(seq64be, 0, sizeof(seq64be)); seq64be[6] = (uint8_t)(priority >> 8); seq64be[7] = (uint8_t)priority; pitem *item = pitem_new(seq64be, frag); if (item == NULL) { dtls1_hm_fragment_free(frag); return 0; } pqueue_insert(ssl->d1->sent_messages, item); return 1; } int dtls1_buffer_message(SSL *ssl) { hm_fragment *frag = dtls1_hm_fragment_new(ssl->init_num, 0); if (!frag) { return 0; } memcpy(frag->fragment, ssl->init_buf->data, ssl->init_num); assert(ssl->d1->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH == (unsigned int)ssl->init_num); frag->msg_header.msg_len = ssl->d1->w_msg_hdr.msg_len; frag->msg_header.seq = ssl->d1->w_msg_hdr.seq; frag->msg_header.type = ssl->d1->w_msg_hdr.type; frag->msg_header.frag_off = 0; frag->msg_header.frag_len = ssl->d1->w_msg_hdr.msg_len; frag->msg_header.is_ccs = 0; frag->msg_header.epoch = ssl->d1->w_epoch; uint16_t priority = dtls1_get_queue_priority(frag->msg_header.seq, 0 /* handshake */); uint8_t seq64be[8]; memset(seq64be, 0, sizeof(seq64be)); seq64be[6] = (uint8_t)(priority >> 8); seq64be[7] = (uint8_t)priority; pitem *item = pitem_new(seq64be, frag); if (item == NULL) { dtls1_hm_fragment_free(frag); return 0; } pqueue_insert(ssl->d1->sent_messages, item); return 1; } int dtls1_send_change_cipher_spec(SSL *ssl, int a, int b) { if (ssl->state == a) { /* Buffer the message to handle retransmits. */ ssl->d1->handshake_write_seq = ssl->d1->next_handshake_write_seq; dtls1_buffer_change_cipher_spec(ssl, ssl->d1->handshake_write_seq); ssl->state = b; } return dtls1_write_change_cipher_spec(ssl, dtls1_use_current_epoch); } /* call this function when the buffered messages are no longer needed */ void dtls1_clear_record_buffer(SSL *ssl) { pitem *item; for (item = pqueue_pop(ssl->d1->sent_messages); item != NULL; item = pqueue_pop(ssl->d1->sent_messages)) { dtls1_hm_fragment_free((hm_fragment *)item->data); pitem_free(item); } } /* don't actually do the writing, wait till the MTU has been retrieved */ void dtls1_set_message_header(SSL *ssl, uint8_t mt, unsigned long len, unsigned short seq_num, unsigned long frag_off, unsigned long frag_len) { struct hm_header_st *msg_hdr = &ssl->d1->w_msg_hdr; msg_hdr->type = mt; msg_hdr->msg_len = len; msg_hdr->seq = seq_num; msg_hdr->frag_off = frag_off; msg_hdr->frag_len = frag_len; } unsigned int dtls1_min_mtu(void) { return kMinMTU; } int dtls1_parse_fragment(CBS *cbs, struct hm_header_st *out_hdr, CBS *out_body) { memset(out_hdr, 0x00, sizeof(struct hm_header_st)); if (!CBS_get_u8(cbs, &out_hdr->type) || !CBS_get_u24(cbs, &out_hdr->msg_len) || !CBS_get_u16(cbs, &out_hdr->seq) || !CBS_get_u24(cbs, &out_hdr->frag_off) || !CBS_get_u24(cbs, &out_hdr->frag_len) || !CBS_get_bytes(cbs, out_body, out_hdr->frag_len)) { return 0; } return 1; }