| /* |
| * Copyright 2021 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "sco_connection.h" |
| |
| #include <hci/hci_packets.h> |
| #include <os/log.h> |
| |
| #include <vector> |
| |
| using namespace rootcanal; |
| using namespace bluetooth::hci; |
| |
| bool ScoConnectionParameters::IsExtended() { |
| uint16_t legacy = (uint16_t)SynchronousPacketTypeBits::HV1_ALLOWED | |
| (uint16_t)SynchronousPacketTypeBits::HV2_ALLOWED | |
| (uint16_t)SynchronousPacketTypeBits::HV3_ALLOWED; |
| uint16_t edr = (uint16_t)SynchronousPacketTypeBits::NO_2_EV3_ALLOWED | |
| (uint16_t)SynchronousPacketTypeBits::NO_3_EV3_ALLOWED | |
| (uint16_t)SynchronousPacketTypeBits::NO_2_EV5_ALLOWED | |
| (uint16_t)SynchronousPacketTypeBits::NO_3_EV5_ALLOWED; |
| return ((packet_type ^ edr) & ~legacy) != 0; |
| } |
| |
| std::optional<ScoLinkParameters> ScoConnectionParameters::GetLinkParameters() { |
| // Coding conversion. |
| uint8_t air_coding_to_air_mode[] = { |
| 0x02, // CVSD |
| 0x00, // u-law |
| 0x01, // A-law |
| 0x03, // transparent data |
| }; |
| |
| // Prioritize eSCO connections. |
| // Packets HV1, HV2, HV3 are tested in a second phase. |
| struct Packet { |
| unsigned length; |
| unsigned slots; |
| |
| Packet(unsigned length, unsigned slots) : length(length), slots(slots) {} |
| }; |
| |
| std::vector<Packet> accepted_packets; |
| accepted_packets.push_back(Packet(0, 1)); // POLL/NULL |
| |
| if (packet_type & (uint16_t)SynchronousPacketTypeBits::EV3_ALLOWED) |
| accepted_packets.push_back(Packet(30, 1)); |
| if (packet_type & (uint16_t)SynchronousPacketTypeBits::EV4_ALLOWED) |
| accepted_packets.push_back(Packet(120, 3)); |
| if (packet_type & (uint16_t)SynchronousPacketTypeBits::EV5_ALLOWED) |
| accepted_packets.push_back(Packet(180, 3)); |
| if ((packet_type & (uint16_t)SynchronousPacketTypeBits::NO_2_EV3_ALLOWED) == |
| 0) |
| accepted_packets.push_back(Packet(60, 1)); |
| if ((packet_type & (uint16_t)SynchronousPacketTypeBits::NO_3_EV3_ALLOWED) == |
| 0) |
| accepted_packets.push_back(Packet(360, 3)); |
| if ((packet_type & (uint16_t)SynchronousPacketTypeBits::NO_2_EV5_ALLOWED) == |
| 0) |
| accepted_packets.push_back(Packet(90, 1)); |
| if ((packet_type & (uint16_t)SynchronousPacketTypeBits::NO_3_EV5_ALLOWED) == |
| 0) |
| accepted_packets.push_back(Packet(540, 3)); |
| |
| // Ignore empty bandwidths for now. |
| if (transmit_bandwidth == 0 || receive_bandwidth == 0) { |
| LOG_WARN("eSCO transmissions with null bandwidths are not supported"); |
| return {}; |
| } |
| |
| // Bandwidth usage of the optimal selection. |
| double best_bandwidth_usage = 1.0; |
| std::optional<ScoLinkParameters> best_parameters = {}; |
| |
| // Explore all packet combinations, select the valid one |
| // with smallest actual bandwidth usage. |
| for (auto tx : accepted_packets) { |
| if (tx.length == 0) continue; |
| |
| unsigned tx_max_interval = (1600 * tx.length) / transmit_bandwidth; |
| |
| for (auto rx : accepted_packets) { |
| if (rx.length == 0) continue; |
| |
| LOG_INFO("Testing combination %u/%u : %u/%u", tx.length, tx.slots, |
| rx.length, rx.slots); |
| |
| unsigned rx_max_interval = (1600 * rx.length) / receive_bandwidth; |
| |
| // Choose the best interval satisfying both. |
| unsigned transmission_interval = |
| std::min(tx_max_interval, rx_max_interval); |
| transmission_interval -= transmission_interval % 2; |
| transmission_interval = std::min(transmission_interval, 254u); |
| |
| LOG_INFO("Transmission interval: %u slots", transmission_interval); |
| |
| // Compute retransmission window. |
| unsigned retransmission_window = |
| retransmission_effort == |
| (uint8_t)RetransmissionEffort::NO_RETRANSMISSION |
| ? 0 |
| : retransmission_effort == |
| (uint8_t)RetransmissionEffort::OPTIMIZED_FOR_POWER |
| ? rx.slots + tx.slots |
| : retransmission_effort == |
| (uint8_t)RetransmissionEffort::OPTIMIZED_FOR_LINK_QUALITY |
| ? 2 * (rx.slots + tx.slots) |
| : 0; |
| |
| LOG_INFO("Retransmission window: %u slots", retransmission_window); |
| |
| // Compute transmission window and validate latency. |
| unsigned transmission_window = |
| tx.slots + rx.slots + retransmission_window; |
| |
| // Validate window. |
| if (transmission_window > transmission_interval) |
| // Oops |
| continue; |
| |
| // Compute and validate latency. |
| unsigned latency = (transmission_window * 1250) / 2; |
| |
| LOG_INFO("Latency: %u us (max %u us)", latency, max_latency * 1000u); |
| |
| if (latency > (1000 * max_latency)) |
| // Oops |
| continue; |
| |
| // We got a valid configuration. |
| // Evaluate the actual bandwidth usage. |
| double bandwidth_usage = |
| (double)transmission_window / (double)transmission_interval; |
| |
| if (bandwidth_usage <= best_bandwidth_usage) { |
| LOG_INFO("Valid combination!"); |
| |
| uint16_t tx_packet_length = |
| (transmit_bandwidth * transmission_interval + 1600 - 1) / 1600; |
| uint16_t rx_packet_length = |
| (receive_bandwidth * transmission_interval + 1600 - 1) / 1600; |
| uint8_t air_coding = voice_setting & 0x3; |
| |
| best_bandwidth_usage = bandwidth_usage; |
| best_parameters = { |
| (uint8_t)transmission_interval, |
| (uint8_t)retransmission_window, |
| rx_packet_length, |
| tx_packet_length, |
| air_coding_to_air_mode[air_coding], |
| true, |
| }; |
| } |
| } |
| } |
| |
| if (best_parameters.has_value()) { |
| return best_parameters; |
| } |
| |
| // Parameter negotiation for SCO connections: |
| // Check packet types and validate bandwidth and latency requirements. |
| |
| if (retransmission_effort == |
| (uint8_t)RetransmissionEffort::OPTIMIZED_FOR_POWER || |
| retransmission_effort == |
| (uint8_t)RetransmissionEffort::OPTIMIZED_FOR_LINK_QUALITY) { |
| LOG_WARN("SCO Retransmission effort must be None or Don't care"); |
| return {}; |
| } |
| |
| uint8_t transmission_interval; |
| uint16_t packet_length; |
| uint8_t air_coding = voice_setting & 0x3; |
| |
| if (packet_type & (uint16_t)SynchronousPacketTypeBits::HV3_ALLOWED) { |
| transmission_interval = 6; |
| packet_length = 30; |
| } else if (packet_type & (uint16_t)SynchronousPacketTypeBits::HV2_ALLOWED) { |
| transmission_interval = 4; |
| packet_length = 20; |
| } else if (packet_type & (uint16_t)SynchronousPacketTypeBits::HV1_ALLOWED) { |
| transmission_interval = 2; |
| packet_length = 10; |
| } else { |
| LOG_WARN("No SCO packet type enabled"); |
| return {}; |
| } |
| |
| best_parameters = { |
| transmission_interval, |
| 0, |
| packet_length, |
| packet_length, |
| air_coding_to_air_mode[air_coding], |
| false, |
| }; |
| return best_parameters; |
| } |
| |
| bool ScoConnection::NegotiateLinkParameters( |
| ScoConnectionParameters const& peer) { |
| if (peer.transmit_bandwidth != 0xffff && |
| peer.transmit_bandwidth != parameters_.receive_bandwidth) { |
| LOG_WARN("Transmit bandwidth requirements cannot be met"); |
| return false; |
| } |
| |
| if (state_ == SCO_STATE_SENT_ESCO_CONNECTION_REQUEST && |
| peer.receive_bandwidth != 0xffff && |
| peer.receive_bandwidth != parameters_.transmit_bandwidth) { |
| LOG_WARN("Receive bandwidth requirements cannot be met"); |
| return false; |
| } |
| |
| // mask out the air coding format bits before comparison, as per 5.3 Vol |
| // 4E 6.12 |
| if ((peer.voice_setting & ~0x3) != (parameters_.voice_setting & ~0x3)) { |
| LOG_WARN("Voice setting requirements cannot be met"); |
| LOG_WARN("Remote voice setting: 0x%04x", |
| static_cast<unsigned>(parameters_.voice_setting)); |
| LOG_WARN("Local voice setting: 0x%04x", |
| static_cast<unsigned>(peer.voice_setting)); |
| return false; |
| } |
| |
| uint16_t packet_type = (peer.packet_type & parameters_.packet_type) & 0x3f; |
| packet_type |= (peer.packet_type | parameters_.packet_type) & 0x3c0; |
| |
| if (packet_type == 0x3c0) { |
| LOG_WARN("Packet type requirements cannot be met"); |
| LOG_WARN("Remote packet type: 0x%04x", |
| static_cast<unsigned>(parameters_.packet_type)); |
| LOG_WARN("Local packet type: 0x%04x", |
| static_cast<unsigned>(peer.packet_type)); |
| return false; |
| } |
| |
| uint16_t max_latency = |
| peer.max_latency == 0xffff ? parameters_.max_latency |
| : parameters_.max_latency == 0xffff |
| ? peer.max_latency |
| : std::min(peer.max_latency, parameters_.max_latency); |
| |
| uint8_t retransmission_effort; |
| if (state_ == SCO_STATE_SENT_SCO_CONNECTION_REQUEST) |
| retransmission_effort = (uint8_t)RetransmissionEffort::NO_RETRANSMISSION; |
| else if (peer.retransmission_effort == parameters_.retransmission_effort || |
| peer.retransmission_effort == |
| (uint8_t)RetransmissionEffort::DO_NOT_CARE) |
| retransmission_effort = parameters_.retransmission_effort; |
| else if (parameters_.retransmission_effort == |
| (uint8_t)RetransmissionEffort::DO_NOT_CARE) |
| retransmission_effort = peer.retransmission_effort; |
| else if (peer.retransmission_effort == |
| (uint8_t)RetransmissionEffort::NO_RETRANSMISSION || |
| parameters_.retransmission_effort == |
| (uint8_t)RetransmissionEffort::NO_RETRANSMISSION) { |
| LOG_WARN("Retransmission effort requirements cannot be met"); |
| LOG_WARN("Remote retransmission effort: 0x%02x", |
| static_cast<unsigned>(parameters_.retransmission_effort)); |
| LOG_WARN("Local retransmission effort: 0x%04x", |
| static_cast<unsigned>(peer.retransmission_effort)); |
| return false; |
| } else { |
| retransmission_effort = (uint8_t)RetransmissionEffort::OPTIMIZED_FOR_POWER; |
| } |
| |
| ScoConnectionParameters negotiated_parameters = { |
| parameters_.transmit_bandwidth, |
| parameters_.receive_bandwidth, |
| max_latency, |
| parameters_.voice_setting, |
| retransmission_effort, |
| packet_type}; |
| |
| auto link_parameters = negotiated_parameters.GetLinkParameters(); |
| if (link_parameters.has_value()) { |
| link_parameters_ = link_parameters.value(); |
| LOG_INFO("Negotiated link parameters for SCO connection:"); |
| LOG_INFO(" Transmission interval: %u slots", |
| static_cast<unsigned>(link_parameters_.transmission_interval)); |
| LOG_INFO(" Retransmission window: %u slots", |
| static_cast<unsigned>(link_parameters_.retransmission_window)); |
| LOG_INFO(" RX packet length: %u bytes", |
| static_cast<unsigned>(link_parameters_.rx_packet_length)); |
| LOG_INFO(" TX packet length: %u bytes", |
| static_cast<unsigned>(link_parameters_.tx_packet_length)); |
| LOG_INFO(" Air mode: %u", |
| static_cast<unsigned>(link_parameters_.air_mode)); |
| } else { |
| LOG_WARN("Failed to derive link parameters"); |
| } |
| return link_parameters.has_value(); |
| } |
| |
| void ScoConnection::StartStream(std::function<AsyncTaskId()> startStream) { |
| ASSERT(!stream_handle_.has_value()); |
| if (datapath_ == ScoDatapath::SPOOFED) { |
| stream_handle_ = startStream(); |
| } |
| } |
| |
| void ScoConnection::StopStream(std::function<void(AsyncTaskId)> stopStream) { |
| if (stream_handle_.has_value()) { |
| stopStream(*stream_handle_); |
| } |
| stream_handle_ = std::nullopt; |
| } |
