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boringssl / boringssl / 83fc0d94d7040544480d42db01554f2421cfc081 / . / ssl / d1_both.cc
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/*
* 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 <openssl/ssl.h>
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <algorithm>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/mem.h>
#include <openssl/rand.h>
#include "../crypto/internal.h"
#include "internal.h"
BSSL_NAMESPACE_BEGIN
// 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;
// BitRange returns a |uint8_t| with bits |start|, inclusive, to |end|,
// exclusive, set.
static uint8_t BitRange(size_t start, size_t end) {
assert(start <= end && end <= 8);
return static_cast<uint8_t>(~((1u << start) - 1) & ((1u << end) - 1));
}
// FirstUnmarkedRangeInByte returns the first unmarked range in bits |b|.
static DTLSMessageBitmap::Range FirstUnmarkedRangeInByte(uint8_t b) {
size_t start, end;
for (start = 0; start < 8; start++) {
if ((b & (1u << start)) == 0) {
break;
}
}
for (end = start; end < 8; end++) {
if ((b & (1u << end)) != 0) {
break;
}
}
return DTLSMessageBitmap::Range{start, end};
}
bool DTLSMessageBitmap::Init(size_t num_bits) {
if (num_bits + 7 < num_bits) {
OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
return false;
}
size_t num_bytes = (num_bits + 7) / 8;
size_t bits_rounded = num_bytes * 8;
if (!bytes_.Init(num_bytes)) {
return false;
}
MarkRange(num_bits, bits_rounded);
first_unmarked_byte_ = 0;
return true;
}
void DTLSMessageBitmap::MarkRange(size_t start, size_t end) {
assert(start <= end);
// Don't bother touching bytes that have already been marked.
start = std::max(start, first_unmarked_byte_ << 3);
// Clamp everything within range.
start = std::min(start, bytes_.size() << 3);
end = std::min(end, bytes_.size() << 3);
if (start >= end) {
return;
}
if ((start >> 3) == (end >> 3)) {
bytes_[start >> 3] |= BitRange(start & 7, end & 7);
} else {
bytes_[start >> 3] |= BitRange(start & 7, 8);
for (size_t i = (start >> 3) + 1; i < (end >> 3); i++) {
bytes_[i] = 0xff;
}
if ((end & 7) != 0) {
bytes_[end >> 3] |= BitRange(0, end & 7);
}
}
// Maintain the |first_unmarked_byte_| invariant. This work is amortized
// across all |MarkRange| calls.
while (first_unmarked_byte_ < bytes_.size() &&
bytes_[first_unmarked_byte_] == 0xff) {
first_unmarked_byte_++;
}
// If the whole message is marked, we no longer need to spend memory on the
// bitmap.
if (first_unmarked_byte_ >= bytes_.size()) {
bytes_.Reset();
first_unmarked_byte_ = 0;
}
}
DTLSMessageBitmap::Range DTLSMessageBitmap::NextUnmarkedRange(
size_t start) const {
// Don't bother looking at bytes that are known to be fully marked.
start = std::max(start, first_unmarked_byte_ << 3);
size_t idx = start >> 3;
if (idx >= bytes_.size()) {
return Range{0, 0};
}
// Look at the bits from |start| up to a byte boundary.
uint8_t byte = bytes_[idx] | BitRange(0, start & 7);
if (byte == 0xff) {
// Nothing unmarked at this byte. Keep searching for an unmarked bit.
for (idx = idx + 1; idx < bytes_.size(); idx++) {
if (bytes_[idx] != 0xff) {
byte = bytes_[idx];
break;
}
}
if (idx >= bytes_.size()) {
return Range{0, 0};
}
}
Range range = FirstUnmarkedRangeInByte(byte);
assert(!range.empty());
bool should_extend = range.end == 8;
range.start += idx << 3;
range.end += idx << 3;
if (!should_extend) {
// The range did not end at a byte boundary. We're done.
return range;
}
// Collect all fully unmarked bytes.
for (idx = idx + 1; idx < bytes_.size(); idx++) {
if (bytes_[idx] != 0) {
break;
}
}
range.end = idx << 3;
// Add any bits from the remaining byte, if any.
if (idx < bytes_.size()) {
Range extra = FirstUnmarkedRangeInByte(bytes_[idx]);
if (extra.start == 0) {
range.end += extra.end;
}
}
return range;
}
// Receiving handshake messages.
static UniquePtr<DTLSIncomingMessage> dtls_new_incoming_message(
const struct hm_header_st *msg_hdr) {
ScopedCBB cbb;
UniquePtr<DTLSIncomingMessage> frag = MakeUnique<DTLSIncomingMessage>();
if (!frag) {
return nullptr;
}
frag->type = msg_hdr->type;
frag->seq = msg_hdr->seq;
// Allocate space for the reassembled message and fill in the header.
if (!frag->data.InitForOverwrite(DTLS1_HM_HEADER_LENGTH + msg_hdr->msg_len)) {
return nullptr;
}
if (!CBB_init_fixed(cbb.get(), frag->data.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)) {
return nullptr;
}
if (!frag->reassembly.Init(msg_hdr->msg_len)) {
return nullptr;
}
return frag;
}
// dtls1_is_current_message_complete returns whether the current handshake
// message is complete.
static bool dtls1_is_current_message_complete(const SSL *ssl) {
size_t idx = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT;
DTLSIncomingMessage *frag = ssl->d1->incoming_messages[idx].get();
return frag != nullptr && frag->reassembly.IsComplete();
}
// 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 DTLSIncomingMessage *dtls1_get_incoming_message(
SSL *ssl, uint8_t *out_alert, 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) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return NULL;
}
size_t idx = msg_hdr->seq % SSL_MAX_HANDSHAKE_FLIGHT;
DTLSIncomingMessage *frag = ssl->d1->incoming_messages[idx].get();
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);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return NULL;
}
return frag;
}
// This is the first fragment from this message.
ssl->d1->incoming_messages[idx] = dtls_new_incoming_message(msg_hdr);
if (!ssl->d1->incoming_messages[idx]) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return NULL;
}
return ssl->d1->incoming_messages[idx].get();
}
bool dtls1_process_handshake_fragments(SSL *ssl, uint8_t *out_alert,
DTLSRecordNumber record_number,
Span<const uint8_t> record) {
bool implicit_ack = false;
bool skipped_fragments = false;
CBS cbs = record;
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);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
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_len > msg_len - frag_off ||
msg_len > ssl_max_handshake_message_len(ssl)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESSIVE_MESSAGE_SIZE);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
if (msg_hdr.seq < ssl->d1->handshake_read_seq) {
// Ignore fragments from the past. This is a retransmit of data we already
// received.
//
// TODO(crbug.com/42290594): Use this to drive retransmits.
continue;
}
assert(record_number.epoch() == ssl->d1->read_epoch.epoch);
if (ssl->d1->next_read_epoch != nullptr) {
// Any any time, we only expect new messages in one epoch. If
// |next_read_epoch| is set, we've started a new epoch but haven't
// received records in it yet. (Once a record is received in the new
// epoch, |next_read_epoch| becomes the current read epoch.) This new
// fragment is in the old epoch, but we expect handshake messages to be in
// the next epoch, so this is an error.
OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESS_HANDSHAKE_DATA);
*out_alert = SSL_AD_UNEXPECTED_MESSAGE;
return false;
}
if (SSL_in_init(ssl) && ssl_has_final_version(ssl) &&
ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
// During the handshake, if we receive any portion of the next flight, the
// peer must have received our most recent flight. In DTLS 1.3, this is an
// implicit ACK. See RFC 9147, Section 7.1.
//
// This only applies during the handshake. After the handshake, the next
// message may be part of a post-handshake transaction. It also does not
// apply immediately after the handshake. As a client, receiving a
// KeyUpdate or NewSessionTicket does not imply the server has received
// our Finished. The server may have sent those messages in half-RTT.
//
// TODO(crbug.com/42290594): Once post-handshake messages are working,
// write a test for the half-RTT KeyUpdate case.
implicit_ack = true;
}
if (msg_hdr.seq - ssl->d1->handshake_read_seq > SSL_MAX_HANDSHAKE_FLIGHT) {
// Ignore fragments too far in the future.
skipped_fragments = true;
continue;
}
DTLSIncomingMessage *frag =
dtls1_get_incoming_message(ssl, out_alert, &msg_hdr);
if (frag == nullptr) {
return false;
}
assert(frag->msg_len() == msg_len);
if (frag->reassembly.IsComplete()) {
// The message is already assembled.
continue;
}
assert(msg_len > 0);
// Copy the body into the fragment.
Span<uint8_t> dest = frag->msg().subspan(frag_off, CBS_len(&body));
OPENSSL_memcpy(dest.data(), CBS_data(&body), CBS_len(&body));
frag->reassembly.MarkRange(frag_off, frag_off + frag_len);
}
if (implicit_ack) {
dtls1_stop_timer(ssl);
dtls_clear_outgoing_messages(ssl);
}
if (!skipped_fragments) {
ssl->d1->records_to_ack.PushBack(record_number);
}
return true;
}
ssl_open_record_t dtls1_open_handshake(SSL *ssl, size_t *out_consumed,
uint8_t *out_alert, Span<uint8_t> in) {
uint8_t type;
DTLSRecordNumber record_number;
Span<uint8_t> record;
auto ret = dtls_open_record(ssl, &type, &record_number, &record, out_consumed,
out_alert, in);
if (ret != ssl_open_record_success) {
return ret;
}
switch (type) {
case SSL3_RT_APPLICATION_DATA:
// In DTLS 1.2, out-of-order application data may be received between
// ChangeCipherSpec and Finished. Discard it.
return ssl_open_record_discard;
case SSL3_RT_CHANGE_CIPHER_SPEC:
// We do not support renegotiation, so encrypted ChangeCipherSpec records
// are illegal.
if (ssl->d1->read_epoch.epoch != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD);
*out_alert = SSL_AD_UNEXPECTED_MESSAGE;
return ssl_open_record_error;
}
if (record.size() != 1u || record[0] != SSL3_MT_CCS) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_CHANGE_CIPHER_SPEC);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return ssl_open_record_error;
}
// Flag the ChangeCipherSpec for later.
// TODO(crbug.com/42290594): Should we reject this in DTLS 1.3?
ssl->d1->has_change_cipher_spec = true;
ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_CHANGE_CIPHER_SPEC,
record);
return ssl_open_record_success;
case SSL3_RT_ACK:
return dtls1_process_ack(ssl, out_alert, record_number, record);
case SSL3_RT_HANDSHAKE:
// Break out to main processing.
break;
default:
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD);
*out_alert = SSL_AD_UNEXPECTED_MESSAGE;
return ssl_open_record_error;
}
if (!dtls1_process_handshake_fragments(ssl, out_alert, record_number,
record)) {
return ssl_open_record_error;
}
return ssl_open_record_success;
}
bool dtls1_get_message(const SSL *ssl, SSLMessage *out) {
if (!dtls1_is_current_message_complete(ssl)) {
return false;
}
size_t idx = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT;
const DTLSIncomingMessage *frag = ssl->d1->incoming_messages[idx].get();
out->type = frag->type;
out->raw = CBS(frag->data);
out->body = CBS(frag->msg());
out->is_v2_hello = false;
if (!ssl->s3->has_message) {
ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HANDSHAKE, out->raw);
ssl->s3->has_message = true;
}
return true;
}
void dtls1_next_message(SSL *ssl) {
assert(ssl->s3->has_message);
assert(dtls1_is_current_message_complete(ssl));
size_t index = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT;
ssl->d1->incoming_messages[index].reset();
ssl->d1->handshake_read_seq++;
ssl->s3->has_message = false;
// If we previously sent a flight, mark it as having a reply, so
// |on_handshake_complete| can manage post-handshake retransmission.
if (ssl->d1->outgoing_messages_complete) {
ssl->d1->flight_has_reply = true;
}
}
bool dtls_has_unprocessed_handshake_data(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->s3->has_message && i == current) {
assert(dtls1_is_current_message_complete(ssl));
continue;
}
if (ssl->d1->incoming_messages[i] != nullptr) {
return true;
}
}
return false;
}
bool 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 false;
}
return true;
}
ssl_open_record_t dtls1_open_change_cipher_spec(SSL *ssl, size_t *out_consumed,
uint8_t *out_alert,
Span<uint8_t> in) {
if (!ssl->d1->has_change_cipher_spec) {
// dtls1_open_handshake processes both handshake and ChangeCipherSpec.
auto ret = dtls1_open_handshake(ssl, out_consumed, out_alert, in);
if (ret != ssl_open_record_success) {
return ret;
}
}
if (ssl->d1->has_change_cipher_spec) {
ssl->d1->has_change_cipher_spec = false;
return ssl_open_record_success;
}
return ssl_open_record_discard;
}
// Sending handshake messages.
void dtls_clear_outgoing_messages(SSL *ssl) {
ssl->d1->outgoing_messages.clear();
ssl->d1->sent_records = nullptr;
ssl->d1->outgoing_written = 0;
ssl->d1->outgoing_offset = 0;
ssl->d1->outgoing_messages_complete = false;
ssl->d1->flight_has_reply = false;
dtls_clear_unused_write_epochs(ssl);
}
void dtls_clear_unused_write_epochs(SSL *ssl) {
ssl->d1->extra_write_epochs.EraseIf(
[ssl](const UniquePtr<DTLSWriteEpoch> &write_epoch) -> bool {
// Non-current epochs may be discarded once there are no incomplete
// outgoing messages that reference them.
//
// TODO(crbug.com/42290594): Epoch 1 (0-RTT) should be retained until
// epoch 3 (app data) is available.
for (const auto &msg : ssl->d1->outgoing_messages) {
if (msg.epoch == write_epoch->epoch() && !msg.IsFullyAcked()) {
return false;
}
}
return true;
});
}
bool dtls1_init_message(const 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 false;
}
return true;
}
bool dtls1_finish_message(const SSL *ssl, CBB *cbb, Array<uint8_t> *out_msg) {
if (!CBBFinishArray(cbb, out_msg) ||
out_msg->size() < DTLS1_HM_HEADER_LENGTH) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
// Fix up the header. Copy the fragment length into the total message
// length.
OPENSSL_memcpy(out_msg->data() + 1,
out_msg->data() + DTLS1_HM_HEADER_LENGTH - 3, 3);
return true;
}
// add_outgoing adds a new handshake message or ChangeCipherSpec to the current
// outgoing flight. It returns true on success and false on error.
static bool add_outgoing(SSL *ssl, bool is_ccs, Array<uint8_t> data) {
if (ssl->d1->outgoing_messages_complete) {
// If we've begun writing a new flight, we received the peer flight. Discard
// the timer and the our flight.
dtls1_stop_timer(ssl);
dtls_clear_outgoing_messages(ssl);
}
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)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
ssl->d1->handshake_write_seq++;
}
DTLSOutgoingMessage msg;
msg.data = std::move(data);
msg.epoch = ssl->d1->write_epoch.epoch();
msg.is_ccs = is_ccs;
// Zero-length messages need 1 bit to track whether the peer has received the
// message header. (Normally the message header is implicitly received when
// any fragment of the message is received at all.)
if (!is_ccs && !msg.acked.Init(std::max(msg.msg_len(), size_t{1}))) {
return false;
}
// This should not fail if |SSL_MAX_HANDSHAKE_FLIGHT| was sized correctly.
//
// TODO(crbug.com/42290594): This can currently fail in DTLS 1.3. The caller
// can configure how many tickets to send, up to kMaxTickets. Additionally, if
// we send 0.5-RTT tickets in 0-RTT, we may even have tickets queued up with
// the server flight.
if (!ssl->d1->outgoing_messages.TryPushBack(std::move(msg))) {
assert(false);
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
return true;
}
bool dtls1_add_message(SSL *ssl, Array<uint8_t> data) {
return add_outgoing(ssl, false /* handshake */, std::move(data));
}
bool dtls1_add_change_cipher_spec(SSL *ssl) {
// DTLS 1.3 disables compatibility mode, which means that DTLS 1.3 never sends
// a ChangeCipherSpec message.
if (ssl_protocol_version(ssl) > TLS1_2_VERSION) {
return true;
}
return add_outgoing(ssl, true /* ChangeCipherSpec */, Array<uint8_t>());
}
// 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.get(), 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.get(), 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_continue,
seal_flush,
};
// seal_next_record seals one record's worth of messages to |out| and advances
// |ssl|'s internal state past the data that was sealed. If progress was made,
// it returns |seal_flush| or |seal_continue| and sets
// |*out_len| to the number of bytes written.
//
// If the function stopped because the next message could not be combined into
// this record, it returns |seal_continue| and the caller should loop again.
// Otherwise, it returns |seal_flush| and the packet is complete (either because
// there are no more messages or the packet is full).
static seal_result_t seal_next_record(SSL *ssl, Span<uint8_t> out,
size_t *out_len) {
*out_len = 0;
// Skip any fully acked messages.
while (ssl->d1->outgoing_written < ssl->d1->outgoing_messages.size() &&
ssl->d1->outgoing_messages[ssl->d1->outgoing_written].IsFullyAcked()) {
ssl->d1->outgoing_offset = 0;
ssl->d1->outgoing_written++;
}
// There was nothing left to write.
if (ssl->d1->outgoing_written >= ssl->d1->outgoing_messages.size()) {
return seal_flush;
}
const auto &first_msg = ssl->d1->outgoing_messages[ssl->d1->outgoing_written];
size_t prefix_len = dtls_seal_prefix_len(ssl, first_msg.epoch);
size_t max_in_len = dtls_seal_max_input_len(ssl, first_msg.epoch, out.size());
if (max_in_len == 0) {
// There is no room for a single record.
return seal_flush;
}
if (first_msg.is_ccs) {
static const uint8_t kChangeCipherSpec[1] = {SSL3_MT_CCS};
DTLSRecordNumber record_number;
if (!dtls_seal_record(ssl, &record_number, out.data(), out_len, out.size(),
SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec,
sizeof(kChangeCipherSpec), first_msg.epoch)) {
return seal_error;
}
ssl_do_msg_callback(ssl, /*is_write=*/1, SSL3_RT_CHANGE_CIPHER_SPEC,
kChangeCipherSpec);
ssl->d1->outgoing_offset = 0;
ssl->d1->outgoing_written++;
return seal_continue;
}
// TODO(crbug.com/374991962): For now, only send one message per record in
// epoch 0. Sending multiple is allowed and more efficient, but breaks
// b/378742138.
const bool allow_multiple_messages = first_msg.epoch != 0;
// Pack as many handshake fragments into one record as we can. We stage the
// fragments in the output buffer, to be sealed in-place.
bool should_continue = false;
Span<uint8_t> fragments = out.subspan(prefix_len, max_in_len);
CBB cbb;
CBB_init_fixed(&cbb, fragments.data(), fragments.size());
DTLSSentRecord sent_record;
sent_record.first_msg = ssl->d1->outgoing_written;
sent_record.first_msg_start = ssl->d1->outgoing_offset;
while (ssl->d1->outgoing_written < ssl->d1->outgoing_messages.size()) {
const auto &msg = ssl->d1->outgoing_messages[ssl->d1->outgoing_written];
if (msg.epoch != first_msg.epoch || msg.is_ccs) {
// We can only pack messages if the epoch matches. There may be more room
// in the packet, so tell the caller to keep going.
should_continue = true;
break;
}
// Decode |msg|'s header.
CBS cbs(msg.data), body_cbs;
struct hm_header_st hdr;
if (!dtls1_parse_fragment(&cbs, &hdr, &body_cbs) || //
hdr.frag_off != 0 || //
hdr.frag_len != CBS_len(&body_cbs) || //
hdr.msg_len != CBS_len(&body_cbs) || //
CBS_len(&cbs) != 0) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return seal_error;
}
// Iterate over every un-acked range in the message, if any.
Span<const uint8_t> body = body_cbs;
for (;;) {
auto range = msg.acked.NextUnmarkedRange(ssl->d1->outgoing_offset);
if (range.empty()) {
// Advance to the next message.
ssl->d1->outgoing_offset = 0;
ssl->d1->outgoing_written++;
break;
}
// Determine how much progress can be made (minimum one byte of progress).
size_t capacity = fragments.size() - CBB_len(&cbb);
if (capacity < DTLS1_HM_HEADER_LENGTH + 1) {
goto packet_full;
}
size_t todo = std::min(range.size(), capacity - DTLS1_HM_HEADER_LENGTH);
// Empty messages are special-cased in ACK tracking. We act as if they
// have one byte, but in reality that byte is tracking the header.
Span<const uint8_t> frag;
if (!body.empty()) {
frag = body.subspan(range.start, todo);
}
// Assemble the fragment.
size_t frag_start = CBB_len(&cbb);
CBB child;
if (!CBB_add_u8(&cbb, hdr.type) || //
!CBB_add_u24(&cbb, hdr.msg_len) || //
!CBB_add_u16(&cbb, hdr.seq) || //
!CBB_add_u24(&cbb, range.start) || //
!CBB_add_u24_length_prefixed(&cbb, &child) || //
!CBB_add_bytes(&child, frag.data(), frag.size()) || //
!CBB_flush(&cbb)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return seal_error;
}
size_t frag_end = CBB_len(&cbb);
// TODO(davidben): It is odd that, on output, we inform the caller of
// retransmits and individual fragments, but on input we only inform the
// caller of complete messages.
ssl_do_msg_callback(ssl, /*is_write=*/1, SSL3_RT_HANDSHAKE,
fragments.subspan(frag_start, frag_end - frag_start));
ssl->d1->outgoing_offset = range.start + todo;
if (todo < range.size()) {
// The packet was the limiting factor.
goto packet_full;
}
}
if (!allow_multiple_messages) {
should_continue = true;
break;
}
}
packet_full:
sent_record.last_msg = ssl->d1->outgoing_written;
sent_record.last_msg_end = ssl->d1->outgoing_offset;
// We could not fit anything. Don't try to make a record.
if (CBB_len(&cbb) == 0) {
assert(!should_continue);
return seal_flush;
}
if (!dtls_seal_record(ssl, &sent_record.number, out.data(), out_len,
out.size(), SSL3_RT_HANDSHAKE, CBB_data(&cbb),
CBB_len(&cbb), first_msg.epoch)) {
return seal_error;
}
// If DTLS 1.3 (or if the version is not yet known and it may be DTLS 1.3),
// save the record number to match against ACKs later.
if (ssl->s3->version == 0 || ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
if (ssl->d1->sent_records == nullptr) {
ssl->d1->sent_records =
MakeUnique<MRUQueue<DTLSSentRecord, DTLS_MAX_ACK_BUFFER>>();
if (ssl->d1->sent_records == nullptr) {
return seal_error;
}
}
ssl->d1->sent_records->PushBack(sent_record);
}
return should_continue ? seal_continue : seal_flush;
}
// 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 bool seal_next_packet(SSL *ssl, Span<uint8_t> out, size_t *out_len) {
size_t total = 0;
for (;;) {
size_t len;
seal_result_t ret = seal_next_record(ssl, out, &len);
switch (ret) {
case seal_error:
return false;
case seal_flush:
case seal_continue:
out = out.subspan(len);
total += len;
break;
}
if (ret == seal_flush) {
break;
}
}
*out_len = total;
return true;
}
static int send_flight(SSL *ssl) {
if (ssl->s3->write_shutdown != ssl_shutdown_none) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PROTOCOL_IS_SHUTDOWN);
return -1;
}
if (ssl->wbio == nullptr) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BIO_NOT_SET);
return -1;
}
dtls1_update_mtu(ssl);
Array<uint8_t> packet;
if (!packet.InitForOverwrite(ssl->d1->mtu)) {
return -1;
}
while (ssl->d1->outgoing_written < ssl->d1->outgoing_messages.size()) {
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, MakeSpan(packet), &packet_len)) {
return -1;
}
if (packet_len == 0 &&
ssl->d1->outgoing_written < ssl->d1->outgoing_messages.size()) {
// We made no progress with the packet size available, but did not reach
// the end.
OPENSSL_PUT_ERROR(SSL, SSL_R_MTU_TOO_SMALL);
return false;
}
if (packet_len != 0) {
int bio_ret = BIO_write(ssl->wbio.get(), packet.data(), 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->s3->rwstate = SSL_ERROR_WANT_WRITE;
return bio_ret;
}
}
}
if (BIO_flush(ssl->wbio.get()) <= 0) {
ssl->s3->rwstate = SSL_ERROR_WANT_WRITE;
return -1;
}
return 1;
}
int dtls1_flush_flight(SSL *ssl, bool post_handshake) {
ssl->d1->outgoing_messages_complete = true;
if (!post_handshake) {
// Our new flight implicitly ACKs the previous flight, so there is no need
// to ACK previous records. This clears the ACK buffer slightly earlier than
// the specification suggests. See the discussion in
// https://mailarchive.ietf.org/arch/msg/tls/kjJnquJOVaWxu5hUCmNzB35eqY0/
//
// TODO(crbug.com/42290594): When we introduce the ACK timer, this should
// also stop the ACK timer.
ssl->d1->records_to_ack.Clear();
}
// Start the retransmission timer for the next flight (if any).
dtls1_start_timer(ssl);
return send_flight(ssl);
}
int dtls1_send_ack(SSL *ssl) {
assert(ssl_protocol_version(ssl) >= TLS1_3_VERSION);
if (ssl->d1->records_to_ack.empty()) {
return 1;
}
// Ensure we don't send so many ACKs that we overflow the MTU. There is a
// 2-byte length prefix and each ACK is 16 bytes.
dtls1_update_mtu(ssl);
size_t max_plaintext =
dtls_seal_max_input_len(ssl, ssl->d1->write_epoch.epoch(), ssl->d1->mtu);
if (max_plaintext < 2 + 16) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MTU_TOO_SMALL); // No room for even one ACK.
return -1;
}
size_t num_acks =
std::min((max_plaintext - 2) / 16, ssl->d1->records_to_ack.size());
// Assemble the ACK. RFC 9147 says to sort ACKs numerically. It is unclear if
// other implementations do this, but go ahead and sort for now. See
// https://mailarchive.ietf.org/arch/msg/tls/kjJnquJOVaWxu5hUCmNzB35eqY0/.
// Remove this if rfc9147bis removes this requirement.
InplaceVector<DTLSRecordNumber, DTLS_MAX_ACK_BUFFER> sorted;
for (size_t i = ssl->d1->records_to_ack.size() - num_acks;
i < ssl->d1->records_to_ack.size(); i++) {
sorted.PushBack(ssl->d1->records_to_ack[i]);
}
std::sort(sorted.begin(), sorted.end());
uint8_t buf[2 + 16 * DTLS_MAX_ACK_BUFFER];
CBB cbb, child;
CBB_init_fixed(&cbb, buf, sizeof(buf));
BSSL_CHECK(CBB_add_u16_length_prefixed(&cbb, &child));
for (const auto &number : sorted) {
BSSL_CHECK(CBB_add_u64(&child, number.epoch()));
BSSL_CHECK(CBB_add_u64(&child, number.sequence()));
}
BSSL_CHECK(CBB_flush(&cbb));
// Encrypt it.
uint8_t record[DTLS1_3_RECORD_HEADER_WRITE_LENGTH + sizeof(buf) +
1 /* record type */ + EVP_AEAD_MAX_OVERHEAD];
size_t record_len;
DTLSRecordNumber record_number;
if (!dtls_seal_record(ssl, &record_number, record, &record_len,
sizeof(record), SSL3_RT_ACK, CBB_data(&cbb),
CBB_len(&cbb), ssl->d1->write_epoch.epoch())) {
return -1;
}
ssl_do_msg_callback(ssl, /*is_write=*/1, SSL3_RT_ACK,
MakeConstSpan(CBB_data(&cbb), CBB_len(&cbb)));
int bio_ret =
BIO_write(ssl->wbio.get(), record, static_cast<int>(record_len));
if (bio_ret <= 0) {
ssl->s3->rwstate = SSL_ERROR_WANT_WRITE;
return bio_ret;
}
return 1;
}
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 send_flight(ssl);
}
unsigned int dtls1_min_mtu(void) { return kMinMTU; }
BSSL_NAMESPACE_END