1 /*
2 * Copyright 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "baseband_sniffer.h"
18
19 #include "log.h"
20 #include "packet/raw_builder.h"
21 #include "pcap.h"
22
23 using std::vector;
24
25 namespace rootcanal {
26
27 #include "bredr_bb.h"
28
BaseBandSniffer(const std::string & filename)29 BaseBandSniffer::BaseBandSniffer(const std::string& filename) {
30 output_.open(filename, std::ios::binary);
31
32 uint32_t linktype = 255; // http://www.tcpdump.org/linktypes.html
33 // LINKTYPE_BLUETOOTH_BREDR_BB
34
35 pcap::WriteHeader(output_, linktype);
36 output_.flush();
37 }
38
TimerTick()39 void BaseBandSniffer::TimerTick() {}
40
AppendRecord(std::unique_ptr<bredr_bb::BaseBandPacketBuilder> packet)41 void BaseBandSniffer::AppendRecord(
42 std::unique_ptr<bredr_bb::BaseBandPacketBuilder> packet) {
43 auto bytes = std::vector<uint8_t>();
44 bytes.reserve(packet->size());
45 bluetooth::packet::BitInserter i(bytes);
46 packet->Serialize(i);
47
48 pcap::WriteRecordHeader(output_, bytes.size());
49 output_.write((char*)bytes.data(), bytes.size());
50 output_.flush();
51 }
52
ReverseByte(uint8_t b)53 static uint8_t ReverseByte(uint8_t b) {
54 static uint8_t lookup[16] = {
55 [0b0000] = 0b0000, [0b0001] = 0b1000, [0b0010] = 0b0100,
56 [0b0011] = 0b1100, [0b0100] = 0b0010, [0b0101] = 0b1010,
57 [0b0110] = 0b0110, [0b0111] = 0b1110, [0b1000] = 0b0001,
58 [0b1001] = 0b1001, [0b1010] = 0b0101, [0b1011] = 0b1101,
59 [0b1100] = 0b0011, [0b1101] = 0b1011, [0b1110] = 0b0111,
60 [0b1111] = 0b1111,
61 };
62
63 return (lookup[b & 0xF] << 4) | lookup[b >> 4];
64 }
65
HeaderErrorCheck(uint8_t uap,uint32_t data)66 static uint8_t HeaderErrorCheck(uint8_t uap, uint32_t data) {
67 // See Bluetooth Core, Vol 2, Part B, 7.1.1
68
69 uint8_t value = ReverseByte(uap);
70
71 for (auto i = 0; i < 10; i++) {
72 bool bit = (value ^ data) & 1;
73 data >>= 1;
74 value >>= 1;
75 if (bit) value ^= 0xe5;
76 }
77
78 return value;
79 }
80
BuildBtPacketHeader(uint8_t uap,uint8_t lt_addr,uint8_t packet_type,bool flow,bool arqn,bool seqn)81 static uint32_t BuildBtPacketHeader(uint8_t uap, uint8_t lt_addr,
82 uint8_t packet_type, bool flow, bool arqn,
83 bool seqn) {
84 // See Bluetooth Core, Vol2, Part B, 6.4
85
86 uint32_t header = (lt_addr & 0x7) | ((packet_type & 0xF) << 3) | (flow << 7) |
87 (arqn << 8) | (seqn << 9);
88
89 header |= (HeaderErrorCheck(uap, header) << 10);
90
91 return header;
92 }
93
IncomingPacket(model::packets::LinkLayerPacketView packet)94 void BaseBandSniffer::IncomingPacket(
95 model::packets::LinkLayerPacketView packet) {
96 auto packet_type = packet.GetType();
97 auto address = packet.GetSourceAddress();
98
99 // Bluetooth Core, Vol2, Part B, 1.2, Figure 1.5
100 uint32_t lap =
101 address.data()[0] | (address.data()[1] << 8) | (address.data()[2] << 16);
102 uint8_t uap = address.data()[3];
103 uint16_t nap = address.data()[4] | (address.data()[5] << 8);
104
105 // http://www.whiterocker.com/bt/LINKTYPE_BLUETOOTH_BREDR_BB.html
106 uint16_t flags =
107 /* BT Packet Header and BR or EDR Payload are de-whitened */ 0x0001 |
108 /* BR or EDR Payload is decrypted */ 0x0008 |
109 /* Reference LAP is valid and led to this packet being captured */
110 0x0010 |
111 /* BR or EDR Payload is present and follows this field */ 0x0020 |
112 /* Reference UAP field is valid for HEC and CRC checking */ 0x0080 |
113 /* CRC portion of the BR or EDR Payload was checked */ 0x0400 |
114 /* CRC portion of the BR or EDR Payload passed its check */ 0x0800;
115
116 uint8_t lt_addr = 0;
117
118 uint8_t rf_channel = 0;
119 uint8_t signal_power = 0;
120 uint8_t noise_power = 0;
121 uint8_t access_code_offenses = 0;
122 uint8_t corrected_header_bits = 0;
123 uint16_t corrected_payload_bits = 0;
124 uint8_t lower_address_part = lap;
125 uint8_t reference_lap = lap;
126 uint8_t reference_uap = uap;
127
128 if (packet_type == model::packets::PacketType::PAGE) {
129 auto page_view = model::packets::PageView::Create(packet);
130 ASSERT(page_view.IsValid());
131
132 uint8_t bt_packet_type = 0b0010; // FHS
133
134 AppendRecord(bredr_bb::FHSAclPacketBuilder::Create(
135 rf_channel, signal_power, noise_power, access_code_offenses,
136 corrected_header_bits, corrected_payload_bits, lower_address_part,
137 reference_lap, reference_uap,
138 BuildBtPacketHeader(uap, lt_addr, bt_packet_type, true, true, true),
139 flags,
140 0, // parity_bits
141 lap,
142 0, // eir
143 0, // sr
144 0, // sp
145 uap, nap, page_view.GetClassOfDevice().ToUint32Legacy(),
146 1, // lt_addr
147 0, // clk
148 0, // page_scan_mode
149 0 // crc
150 ));
151 } else if (packet_type == model::packets::PacketType::LMP) {
152 auto lmp_view = model::packets::LmpView::Create(packet);
153 ASSERT(lmp_view.IsValid());
154 auto lmp_bytes = std::vector<uint8_t>(lmp_view.GetPayload().begin(),
155 lmp_view.GetPayload().end());
156
157 uint8_t bt_packet_type = 0b0011; // DM1
158
159 AppendRecord(bredr_bb::DM1AclPacketBuilder::Create(
160 rf_channel, signal_power, noise_power, access_code_offenses,
161 corrected_header_bits, corrected_payload_bits, lower_address_part,
162 reference_lap, reference_uap,
163 BuildBtPacketHeader(uap, lt_addr, bt_packet_type, true, true, true),
164 flags,
165 0x3, // llid
166 1, // flow
167 std::make_unique<bluetooth::packet::RawBuilder>(lmp_bytes),
168 0 // crc
169 ));
170 }
171 }
172
173 } // namespace rootcanal
174