1 // Copyright 2023 The Pigweed Authors
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
4 // use this file except in compliance with the License. You may obtain a copy of
5 // the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12 // License for the specific language governing permissions and limitations under
13 // the License.
14
15 #include "pw_bluetooth_sapphire/internal/host/sm/pairing_channel.h"
16
17 #include <pw_assert/check.h>
18
19 #include "pw_bluetooth_sapphire/internal/host/common/byte_buffer.h"
20 #include "pw_bluetooth_sapphire/internal/host/l2cap/channel.h"
21 #include "pw_bluetooth_sapphire/internal/host/l2cap/scoped_channel.h"
22 #include "pw_bluetooth_sapphire/internal/host/sm/smp.h"
23
24 namespace bt::sm {
25
PairingChannel(l2cap::Channel::WeakPtr chan,fit::closure timer_resetter)26 PairingChannel::PairingChannel(l2cap::Channel::WeakPtr chan,
27 fit::closure timer_resetter)
28 : chan_(std::move(chan)),
29 reset_timer_(std::move(timer_resetter)),
30 weak_self_(this) {
31 PW_CHECK(chan_);
32 if (chan_->link_type() == bt::LinkType::kLE) {
33 PW_CHECK(chan_->id() == l2cap::kLESMPChannelId);
34 } else if (chan_->link_type() == bt::LinkType::kACL) {
35 PW_CHECK(chan_->id() == l2cap::kSMPChannelId);
36 } else {
37 PW_CRASH("unsupported link type for SMP!");
38 }
39 auto self = weak_self_.GetWeakPtr();
40 chan_->Activate(
41 [self](ByteBufferPtr sdu) {
42 if (self.is_alive()) {
43 self->OnRxBFrame(std::move(sdu));
44 } else {
45 bt_log(WARN, "sm", "dropped packet on SM channel!");
46 }
47 },
48 [self]() {
49 if (self.is_alive()) {
50 self->OnChannelClosed();
51 }
52 });
53 // The SMP fixed channel's MTU must be >=23 bytes (kNoSecureConnectionsMTU)
54 // per spec V5.0 Vol. 3 Part H 3.2. As SMP operates on a fixed channel, there
55 // is no way to configure this MTU, so we expect that L2CAP always provides a
56 // channel with a sufficiently large MTU. This assertion serves as an explicit
57 // acknowledgement of that contract between L2CAP and SMP.
58 PW_CHECK(chan_->max_tx_sdu_size() >= kNoSecureConnectionsMtu &&
59 chan_->max_rx_sdu_size() >= kNoSecureConnectionsMtu);
60 }
61
PairingChannel(l2cap::Channel::WeakPtr chan)62 PairingChannel::PairingChannel(l2cap::Channel::WeakPtr chan)
63 : PairingChannel(std::move(chan), []() {}) {}
64
SetChannelHandler(Handler::WeakPtr new_handler)65 void PairingChannel::SetChannelHandler(Handler::WeakPtr new_handler) {
66 PW_CHECK(new_handler.is_alive());
67 bt_log(TRACE, "sm", "changing pairing channel handler");
68 handler_ = std::move(new_handler);
69 }
70
OnRxBFrame(ByteBufferPtr sdu)71 void PairingChannel::OnRxBFrame(ByteBufferPtr sdu) {
72 if (handler_.is_alive()) {
73 handler_->OnRxBFrame(std::move(sdu));
74 } else {
75 bt_log(WARN, "sm", "no handler to receive L2CAP packet callback!");
76 }
77 }
78
OnChannelClosed()79 void PairingChannel::OnChannelClosed() {
80 if (handler_.is_alive()) {
81 handler_->OnChannelClosed();
82 } else {
83 bt_log(WARN, "sm", "no handler to receive L2CAP channel closed callback!");
84 }
85 }
86
87 } // namespace bt::sm
88