/* * 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 "../crypto/internal.h" #include "internal.h" namespace bssl { /* 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; /* Receiving handshake messages. */ static void dtls1_hm_fragment_free(hm_fragment *frag) { if (frag == NULL) { return; } OPENSSL_free(frag->data); OPENSSL_free(frag->reassembly); OPENSSL_free(frag); } static hm_fragment *dtls1_hm_fragment_new(const struct hm_header_st *msg_hdr) { ScopedCBB cbb; hm_fragment *frag = (hm_fragment *)OPENSSL_malloc(sizeof(hm_fragment)); if (frag == NULL) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); return NULL; } OPENSSL_memset(frag, 0, sizeof(hm_fragment)); frag->type = msg_hdr->type; frag->seq = msg_hdr->seq; frag->msg_len = msg_hdr->msg_len; /* Allocate space for the reassembled message and fill in the header. */ frag->data = (uint8_t *)OPENSSL_malloc(DTLS1_HM_HEADER_LENGTH + msg_hdr->msg_len); if (frag->data == NULL) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); goto err; } if (!CBB_init_fixed(cbb.get(), frag->data, DTLS1_HM_HEADER_LENGTH) || !CBB_add_u8(cbb.get(), msg_hdr->type) || !CBB_add_u24(cbb.get(), msg_hdr->msg_len) || !CBB_add_u16(cbb.get(), msg_hdr->seq) || !CBB_add_u24(cbb.get(), 0 /* frag_off */) || !CBB_add_u24(cbb.get(), msg_hdr->msg_len) || !CBB_finish(cbb.get(), NULL, NULL)) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); goto err; } /* If the handshake message is empty, |frag->reassembly| is NULL. */ if (msg_hdr->msg_len > 0) { /* Initialize reassembly bitmask. */ if (msg_hdr->msg_len + 7 < msg_hdr->msg_len) { OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); goto err; } size_t bitmask_len = (msg_hdr->msg_len + 7) / 8; frag->reassembly = (uint8_t *)OPENSSL_malloc(bitmask_len); if (frag->reassembly == NULL) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); goto err; } OPENSSL_memset(frag->reassembly, 0, bitmask_len); } return frag; err: dtls1_hm_fragment_free(frag); return NULL; } /* bit_range returns a |uint8_t| with bits |start|, inclusive, to |end|, * exclusive, set. */ static 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 msg_len = frag->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 (size_t 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 (size_t 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; } /* dtls1_is_current_message_complete returns one if the current handshake * message is complete and zero otherwise. */ static int dtls1_is_current_message_complete(const SSL *ssl) { hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT]; return frag != NULL && frag->reassembly == NULL; } /* dtls1_get_incoming_message returns the incoming 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_incoming_message( SSL *ssl, const struct hm_header_st *msg_hdr) { if (msg_hdr->seq < ssl->d1->handshake_read_seq || msg_hdr->seq - ssl->d1->handshake_read_seq >= SSL_MAX_HANDSHAKE_FLIGHT) { return NULL; } size_t idx = msg_hdr->seq % SSL_MAX_HANDSHAKE_FLIGHT; hm_fragment *frag = ssl->d1->incoming_messages[idx]; if (frag != NULL) { assert(frag->seq == msg_hdr->seq); /* The new fragment must be compatible with the previous fragments from this * message. */ if (frag->type != msg_hdr->type || frag->msg_len != msg_hdr->msg_len) { OPENSSL_PUT_ERROR(SSL, SSL_R_FRAGMENT_MISMATCH); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return NULL; } return frag; } /* This is the first fragment from this message. */ frag = dtls1_hm_fragment_new(msg_hdr); if (frag == NULL) { return NULL; } ssl->d1->incoming_messages[idx] = frag; return frag; } /* dtls1_process_handshake_record reads a record for the handshake and processes * it. It returns one on success and 0 or -1 on error. */ static int dtls1_process_handshake_record(SSL *ssl) { SSL3_RECORD *rr = &ssl->s3->rrec; if (rr->length == 0) { int ret = dtls1_get_record(ssl); if (ret <= 0) { return ret; } } switch (rr->type) { case SSL3_RT_APPLICATION_DATA: /* Unencrypted application data records are always illegal. */ if (ssl->s3->aead_read_ctx->is_null_cipher()) { ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE); OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); return -1; } /* Out-of-order application data may be received between ChangeCipherSpec * and finished. Discard it. */ rr->length = 0; ssl_read_buffer_discard(ssl); return 1; case SSL3_RT_CHANGE_CIPHER_SPEC: /* We do not support renegotiation, so encrypted ChangeCipherSpec records * are illegal. */ if (!ssl->s3->aead_read_ctx->is_null_cipher()) { ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE); OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); return -1; } if (rr->length != 1 || rr->data[0] != SSL3_MT_CCS) { OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_CHANGE_CIPHER_SPEC); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return -1; } /* Flag the ChangeCipherSpec for later. */ ssl->d1->has_change_cipher_spec = true; ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_CHANGE_CIPHER_SPEC, rr->data, rr->length); rr->length = 0; ssl_read_buffer_discard(ssl); return 1; case SSL3_RT_HANDSHAKE: /* Break out to main processing. */ break; default: 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; } /* The encrypted epoch in DTLS has only one handshake message. */ if (ssl->d1->r_epoch == 1 && msg_hdr.seq != ssl->d1->handshake_read_seq) { OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE); return -1; } if (msg_hdr.seq < ssl->d1->handshake_read_seq || msg_hdr.seq > (unsigned)ssl->d1->handshake_read_seq + SSL_MAX_HANDSHAKE_FLIGHT) { /* Ignore fragments from the past, or ones too far in the future. */ continue; } hm_fragment *frag = dtls1_get_incoming_message(ssl, &msg_hdr); if (frag == NULL) { return -1; } assert(frag->msg_len == msg_len); if (frag->reassembly == NULL) { /* The message is already assembled. */ continue; } assert(msg_len > 0); /* Copy the body into the fragment. */ OPENSSL_memcpy(frag->data + DTLS1_HM_HEADER_LENGTH + 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; } int dtls1_get_message(SSL *ssl) { if (ssl->s3->tmp.reuse_message) { /* There must be a current message. */ assert(ssl->init_msg != NULL); ssl->s3->tmp.reuse_message = 0; } else { dtls1_release_current_message(ssl, 0 /* don't free buffer */); } /* Process handshake records until the current message is ready. */ while (!dtls1_is_current_message_complete(ssl)) { int ret = dtls1_process_handshake_record(ssl); if (ret <= 0) { return ret; } } hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT]; assert(frag != NULL); assert(frag->reassembly == NULL); assert(ssl->d1->handshake_read_seq == frag->seq); /* TODO(davidben): This function has a lot of implicit outputs. Simplify the * |ssl_get_message| API. */ ssl->s3->tmp.message_type = frag->type; ssl->init_msg = frag->data + DTLS1_HM_HEADER_LENGTH; ssl->init_num = frag->msg_len; ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HANDSHAKE, frag->data, ssl->init_num + DTLS1_HM_HEADER_LENGTH); return 1; } void dtls1_get_current_message(const SSL *ssl, CBS *out) { assert(dtls1_is_current_message_complete(ssl)); hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT]; CBS_init(out, frag->data, DTLS1_HM_HEADER_LENGTH + frag->msg_len); } void dtls1_release_current_message(SSL *ssl, int free_buffer) { if (ssl->init_msg == NULL) { return; } assert(dtls1_is_current_message_complete(ssl)); size_t index = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT; dtls1_hm_fragment_free(ssl->d1->incoming_messages[index]); ssl->d1->incoming_messages[index] = NULL; ssl->d1->handshake_read_seq++; ssl->init_msg = NULL; ssl->init_num = 0; } void dtls_clear_incoming_messages(SSL *ssl) { for (size_t i = 0; i < SSL_MAX_HANDSHAKE_FLIGHT; i++) { dtls1_hm_fragment_free(ssl->d1->incoming_messages[i]); ssl->d1->incoming_messages[i] = NULL; } } int dtls_has_incoming_messages(const SSL *ssl) { size_t current = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT; for (size_t i = 0; i < SSL_MAX_HANDSHAKE_FLIGHT; i++) { /* Skip the current message. */ if (ssl->init_msg != NULL && i == current) { assert(dtls1_is_current_message_complete(ssl)); continue; } if (ssl->d1->incoming_messages[i] != NULL) { return 1; } } return 0; } int dtls1_parse_fragment(CBS *cbs, struct hm_header_st *out_hdr, CBS *out_body) { OPENSSL_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; } int dtls1_read_change_cipher_spec(SSL *ssl) { /* Process handshake records until there is a ChangeCipherSpec. */ while (!ssl->d1->has_change_cipher_spec) { int ret = dtls1_process_handshake_record(ssl); if (ret <= 0) { return ret; } } ssl->d1->has_change_cipher_spec = false; return 1; } /* Sending handshake messages. */ void dtls_clear_outgoing_messages(SSL *ssl) { for (size_t i = 0; i < ssl->d1->outgoing_messages_len; i++) { OPENSSL_free(ssl->d1->outgoing_messages[i].data); ssl->d1->outgoing_messages[i].data = NULL; } ssl->d1->outgoing_messages_len = 0; ssl->d1->outgoing_written = 0; ssl->d1->outgoing_offset = 0; } int dtls1_init_message(SSL *ssl, CBB *cbb, CBB *body, uint8_t type) { /* Pick a modest size hint to save most of the |realloc| calls. */ if (!CBB_init(cbb, 64) || !CBB_add_u8(cbb, type) || !CBB_add_u24(cbb, 0 /* length (filled in later) */) || !CBB_add_u16(cbb, ssl->d1->handshake_write_seq) || !CBB_add_u24(cbb, 0 /* offset */) || !CBB_add_u24_length_prefixed(cbb, body)) { return 0; } return 1; } int dtls1_finish_message(SSL *ssl, CBB *cbb, uint8_t **out_msg, size_t *out_len) { *out_msg = NULL; if (!CBB_finish(cbb, out_msg, out_len) || *out_len < DTLS1_HM_HEADER_LENGTH) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); OPENSSL_free(*out_msg); return 0; } /* Fix up the header. Copy the fragment length into the total message * length. */ OPENSSL_memcpy(*out_msg + 1, *out_msg + DTLS1_HM_HEADER_LENGTH - 3, 3); return 1; } /* add_outgoing adds a new handshake message or ChangeCipherSpec to the current * outgoing flight. It returns one on success and zero on error. In both cases, * it takes ownership of |data| and releases it with |OPENSSL_free| when * done. */ static int add_outgoing(SSL *ssl, int is_ccs, uint8_t *data, size_t len) { static_assert(SSL_MAX_HANDSHAKE_FLIGHT < (1 << 8 * sizeof(ssl->d1->outgoing_messages_len)), "outgoing_messages_len is too small"); if (ssl->d1->outgoing_messages_len >= SSL_MAX_HANDSHAKE_FLIGHT) { assert(0); OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); OPENSSL_free(data); return 0; } if (!is_ccs) { /* TODO(svaldez): Move this up a layer to fix abstraction for SSLTranscript * on hs. */ if (ssl->s3->hs != NULL && !ssl->s3->hs->transcript.Update(data, len)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); OPENSSL_free(data); return 0; } ssl->d1->handshake_write_seq++; } DTLS_OUTGOING_MESSAGE *msg = &ssl->d1->outgoing_messages[ssl->d1->outgoing_messages_len]; msg->data = data; msg->len = len; msg->epoch = ssl->d1->w_epoch; msg->is_ccs = is_ccs; ssl->d1->outgoing_messages_len++; return 1; } int dtls1_add_message(SSL *ssl, uint8_t *data, size_t len) { return add_outgoing(ssl, 0 /* handshake */, data, len); } int dtls1_add_change_cipher_spec(SSL *ssl) { return add_outgoing(ssl, 1 /* ChangeCipherSpec */, NULL, 0); } int dtls1_add_alert(SSL *ssl, uint8_t level, uint8_t desc) { /* The |add_alert| path is only used for warning alerts for now, which DTLS * never sends. This will be implemented later once closure alerts are * converted. */ assert(0); OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return 0; } /* dtls1_update_mtu updates the current MTU from the BIO, ensuring it is above * the minimum. */ static void dtls1_update_mtu(SSL *ssl) { /* TODO(davidben): No consumer implements |BIO_CTRL_DGRAM_SET_MTU| and the * only |BIO_CTRL_DGRAM_QUERY_MTU| implementation could use * |SSL_set_mtu|. Does this need to be so complex? */ 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()); } enum seal_result_t { seal_error, seal_no_progress, seal_partial, seal_success, }; /* seal_next_message seals |msg|, which must be the next message, to |out|. If * progress was made, it returns |seal_partial| or |seal_success| and sets * |*out_len| to the number of bytes written. */ static enum seal_result_t seal_next_message(SSL *ssl, uint8_t *out, size_t *out_len, size_t max_out, const DTLS_OUTGOING_MESSAGE *msg) { assert(ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len); assert(msg == &ssl->d1->outgoing_messages[ssl->d1->outgoing_written]); enum dtls1_use_epoch_t use_epoch = dtls1_use_current_epoch; if (ssl->d1->w_epoch >= 1 && msg->epoch == ssl->d1->w_epoch - 1) { use_epoch = dtls1_use_previous_epoch; } else if (msg->epoch != ssl->d1->w_epoch) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return seal_error; } size_t overhead = dtls_max_seal_overhead(ssl, use_epoch); size_t prefix = dtls_seal_prefix_len(ssl, use_epoch); if (msg->is_ccs) { /* Check there is room for the ChangeCipherSpec. */ static const uint8_t kChangeCipherSpec[1] = {SSL3_MT_CCS}; if (max_out < sizeof(kChangeCipherSpec) + overhead) { return seal_no_progress; } if (!dtls_seal_record(ssl, out, out_len, max_out, SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec, sizeof(kChangeCipherSpec), use_epoch)) { return seal_error; } ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec, sizeof(kChangeCipherSpec)); return seal_success; } /* DTLS messages are serialized as a single fragment in |msg|. */ CBS cbs, body; struct hm_header_st hdr; CBS_init(&cbs, msg->data, msg->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, ssl->d1->outgoing_offset) || CBS_len(&cbs) != 0) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return seal_error; } /* Determine how much progress can be made. */ if (max_out < DTLS1_HM_HEADER_LENGTH + 1 + overhead || max_out < prefix) { return seal_no_progress; } size_t todo = CBS_len(&body); if (todo > max_out - DTLS1_HM_HEADER_LENGTH - overhead) { todo = max_out - DTLS1_HM_HEADER_LENGTH - overhead; } /* Assemble a fragment, to be sealed in-place. */ ScopedCBB cbb; uint8_t *frag = out + prefix; size_t max_frag = max_out - prefix, frag_len; if (!CBB_init_fixed(cbb.get(), frag, max_frag) || !CBB_add_u8(cbb.get(), hdr.type) || !CBB_add_u24(cbb.get(), hdr.msg_len) || !CBB_add_u16(cbb.get(), hdr.seq) || !CBB_add_u24(cbb.get(), ssl->d1->outgoing_offset) || !CBB_add_u24(cbb.get(), todo) || !CBB_add_bytes(cbb.get(), CBS_data(&body), todo) || !CBB_finish(cbb.get(), NULL, &frag_len)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return seal_error; } ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_HANDSHAKE, frag, frag_len); if (!dtls_seal_record(ssl, out, out_len, max_out, SSL3_RT_HANDSHAKE, out + prefix, frag_len, use_epoch)) { return seal_error; } if (todo == CBS_len(&body)) { /* The next message is complete. */ ssl->d1->outgoing_offset = 0; return seal_success; } ssl->d1->outgoing_offset += todo; return seal_partial; } /* seal_next_packet writes as much of the next flight as possible to |out| and * advances |ssl->d1->outgoing_written| and |ssl->d1->outgoing_offset| as * appropriate. */ static int seal_next_packet(SSL *ssl, uint8_t *out, size_t *out_len, size_t max_out) { int made_progress = 0; size_t total = 0; assert(ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len); for (; ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len; ssl->d1->outgoing_written++) { const DTLS_OUTGOING_MESSAGE *msg = &ssl->d1->outgoing_messages[ssl->d1->outgoing_written]; size_t len; enum seal_result_t ret = seal_next_message(ssl, out, &len, max_out, msg); switch (ret) { case seal_error: return 0; case seal_no_progress: goto packet_full; case seal_partial: case seal_success: out += len; max_out -= len; total += len; made_progress = 1; if (ret == seal_partial) { goto packet_full; } break; } } packet_full: /* The MTU was too small to make any progress. */ if (!made_progress) { OPENSSL_PUT_ERROR(SSL, SSL_R_MTU_TOO_SMALL); return 0; } *out_len = total; return 1; } int dtls1_flush_flight(SSL *ssl) { dtls1_update_mtu(ssl); int ret = -1; uint8_t *packet = (uint8_t *)OPENSSL_malloc(ssl->d1->mtu); if (packet == NULL) { OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); goto err; } while (ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len) { uint8_t old_written = ssl->d1->outgoing_written; uint32_t old_offset = ssl->d1->outgoing_offset; size_t packet_len; if (!seal_next_packet(ssl, packet, &packet_len, ssl->d1->mtu)) { goto err; } int bio_ret = BIO_write(ssl->wbio, packet, packet_len); if (bio_ret <= 0) { /* Retry this packet the next time around. */ ssl->d1->outgoing_written = old_written; ssl->d1->outgoing_offset = old_offset; ssl->rwstate = SSL_WRITING; ret = bio_ret; goto err; } } if (BIO_flush(ssl->wbio) <= 0) { ssl->rwstate = SSL_WRITING; goto err; } ret = 1; err: OPENSSL_free(packet); return ret; } int dtls1_retransmit_outgoing_messages(SSL *ssl) { /* Rewind to the start of the flight and write it again. * * TODO(davidben): This does not allow retransmits to be resumed on * non-blocking write. */ ssl->d1->outgoing_written = 0; ssl->d1->outgoing_offset = 0; return dtls1_flush_flight(ssl); } unsigned int dtls1_min_mtu(void) { return kMinMTU; } } // namespace bssl