BT bluedroid bond 配对

dupz11192023-11-10 15:27

基于Android P版本分析

BT bluedroid BOND

简述

bluedroid和scan流程分析完成之后，我们紧接着就是开始分析配对。

我们需要知道，蓝牙配对是什么。

从UI上来讲，是呈现给用于一个已配对的状态体验；而针对蓝牙设备而言，是两个设备之间的一次消息传递和信任建立；

  • 信任建立：我们知道，在两个蓝牙设备首次连接的时候，通常需要进行PIN码确认，除了一些特殊的蓝牙设备，如蓝牙音响、蓝牙耳机之类的功能比较简单的设备，而手机与手机之间的蓝牙互联通常需要PIN码确认，只要当PIN码确认OK之后，蓝牙通路才算打通，手机上会显示已连接的字样；
  • PIN码：Personal identification number，简称PIN，PIN码是一串数字构成的通行码，用来认证使用者身份，授权他人进入系统；例如我们创建的蓝牙文件传输，该功能的基础就是蓝牙设备必须已经配对成功，如果没对或者配对失败，是无法访问对应的系统的，也就无法将文件推送过去；

蓝牙配对

蓝牙双端设备通信依赖于极不可靠的无线通信，所以通信过程要机型数据加密和数据完整性校验操作等；

蓝牙配对过程：

  • 配对（Pairing）：创建一个或多个共享密钥SSK（SharedSecretKeys）的过程；
  • 绑定（Bonding）：将在配对过程中生成的密钥存储起来的行为，以便在后续连接时使用，创建一个可信任的设备；
  • 设备授权（DeviceAuthentication）：验证两个设备拥有相同的密钥；
  • 消息加密（Encryption）：保障消息的机密性；
  • 消息完整性（MessageIntegrity）：防止伪造消息；

针对Key，如果双方设备不存在可用的Key，则需要通过PIN或者SSP的方式创建一个Key；

Pairing的国策红肿借助PIN码和一串随机的数字以及br_addr地址创建一个初始化的Key；

初始化Key计算成功后就会创建linkkey，linkkey用于后续两设备连接时进行授权，以此来保护通信免受三方攻击和窃听；

bluedroid bond

bond 流程

  • 删除之前存在的指定BD_ADDR设备的linkKey，该BD_ADDR设备为远程设备，以车机侧为Master，手机侧为slave，删除的linkKey为master侧保存的slave相关的linkKey；

  • 读取远程设备的name，这个name通过scan阶段搜索到的deviceInfo信息中的BD_ADDR来获取对应的RemoteDevice Name；

    • 读取Remote Device Name的指令发送之后，Controller进行响应，向上层上报了Remote Host Supported Feature Notification Event，在该阶段中，用于创建设备信息初始化基础参数并记录在数据库中；
    • 最后Controller响应HCI_REMOTE_NAME_REQUEST指令，返回REMOTE_NAME_REQUEST_COMPLETE_EVT，首先先取消读取Name的超时监听，然后根据BD_ADDR参数来查询对应的结构体信息，然后就是在该函数中触发ACL链路连接；

  • ACL链路的连接触发逻辑是在HCI_REMOTE_NAME_REQUEST的Response中触发的，发送HCI_CREATE_CONNECTION指令，用于建立和指定设备间的连接，并在指令执行完成之后，host接收到对应的Command_Complete_Evt；

  • Connection_Complete_Evt上报之后，在该Response中，Host向Controller发送了HCI_READ_CLOCK_OFFSET指令，用于读取远程设备的时钟偏移，即进行时钟同步，好进行跳频。结束时host会接收到HCI_READ_CLOCK_OFFSET_COMPLETE事件通知；

  • 同样，Connection_Complete_Evt上报之后，且Host已经向Controller发送了HCI_READ_CLOCK_OFFSET指令之后，Host会向Controller发送HCI_WRITE_POLICY_SETTINGS指令，用于设置link策略，即用来设置本地Link Manager在Connection_Handle对应ACL连接上关于Role switch、Park State、Hold Mode、Sniff Mode上的处理策略。在命令完成后，host会接收到HCI_Command_Complete事件通知；

  • link策略Write指令发送之后，设置link监控超时时间，命令执行完毕后host会接收到HCI_Command_Complete事件通知；

  • 接下来就是读取版本信息、读取远程设备支持的能力列表、扩展能力列表；

  • 接下来是第二个核心点：Authentication Request，发起授权请求，存在两种授权方式：

    • 支持SSP：Host下发 HCI_LINK_KEY_REQUEST_NEGATIVE_REPLY 指令；
    • 不支持SSP，只支持Authentication：Host下发 HCI_LINK_REQUEST_REPLY 指令；

    在配对过程中给用户确认的弹窗，就是基于SSP；

    但是由于设备的输入输出不同，SSP采用的方式也不同，比如如果对端不能输入也不能确认，那就无法弹窗提示；

    • 因此在进行SSP是，要先了解设备的IO特性，Controller会向Host发送 HCI_IO_CAPABILITY_REQUEST，用于查看设备是否支持输入输出；

    双方设备的IO能力检测完成后，就可以选择何种方式的SSP，SSP完成之后，就可以生成对应的linkKey。

    至此，Authetication阶段就结束了；

  • 在配对或者鉴权完成后的任何时间点都可以发起加密，通过发送 HCI_Set_Connection_Encryption 完成。对链路层加密，加密结束之后Host会接收到HCI_ENCRYPTION_CHANGE事件通知；

在上图中还提及到了Disconnect，但是从目前的情况来看，配对过程中好像没有涉及到这个过程，后续分析涉及到再说；

流程分析

cancelDiscovery

我们开启扫描之后，扫描这个动作会一致持续，直到主动停止或者被其他动作打断才会停止；

扫描之后的动作一般情况下为配对，所以，在配对之前，会调用cancelDiscovery方法向底层发送停止扫描的指令；

createBond

在该阶段，在ACL Connection之前，首先先会通过HCI向Controller发送获取RemoteDevice Name的指令，而在Controller响应该指令的时候，会向Host发送两个Event：

  • Remote Supported Host Features Notification event：用于创建设备信息初始化基础参数并记录在数据库中，Link Manager在获取远端设备名字的同时会获取远端设备LMP features的pages 0 和 1；
  • Remote Name Request Complete event：用于响应 Remote Name Request Command 指令，返回对应RemoteDevice 的 Name；

在Remote Name Request Complete event对应的响应函数的最后，会通过btm_sec_dd_create_conn函数发送ACL Connection指令；

btm_sec_dd_create_conn

在该函数中，获取到当前激活的acl链路数量，然后发送了 HCI_CREATE_CONNECTION 指令，然后通过alarm_set_on_mloop函数启动了l2cap连接的超时监控；

然后就可以等待HCI_CREATE_CONNECTION 指令对应的HCI_CONNECTION_COMP_EVT 事件，而在该Response中，用于响应Connection Complete阶段需要执行的一些逻辑；

而在HCI_CONNETION_COMP_EVT事件中，主要做了如下几件事：

  • btm_sec_connected

    • 设定page状态为false；
    • 更新设备记录的时间戳；
    • 更新设备类型；
    • 记录要连接的设备信息，创建tACL_CONN结构体记录设备信息；
    • 开始所需要的安全流程；

  • l2c_link_hci_conn_comp

    • 修改acl层的busy状态；
    • 修改linkCb中的link_state；
    • 发送对端设备信息；
    • 更新设备信息，发送HCI_WRITE_POLICY_SETTINGS指令，将link策略设置到芯片中；
    • 设定link超时监控；

btm_sec_start_authentication

HCI_CONNECTION_COMP_EVT 事件响应结束后，紧接着再响应 Remote Name Request Complete event 事件；

在 Remote Name Request Complete event 事件中执行完ACL Connection之后，紧接着执行 btm_sec_start_authentication函数，用于启动authentication；

在这个阶段，主要执行了如下几件事：

  • 开启授权阶段；
  • 修改sm4字段为BTM_SM4_TRUE；
  • 更新系统额busy层级达到BTM_BLI_ACL_UP_EVT；
  • 双端设备的IO能力检测；
  • 修改配对状态为WAIT_LOCAL_IOCAPS；

授权工作结束之后，紧接着就是加密设置；

btu_hcif_encryption_change_evt

建立连接后，链路层可以根据主机的请求对数据包启用加密操作；

  1. 主机A发送LE Start Encryption HCI命令以请求链路层启动加密。在此过程中，交换两个参数，IV和SKD。
  2. LL A收到主机的加密请求后，向LL B发送LL_ENC_REQ PDU请求加密。
  3. LL B收到LL_ENC_REQ PDU后，向主机B发送LE长期密钥请求HCI事件。
  4. 如果主机B可以提供LTK，则通过LE长期密钥请求应答HCI命令向LL B提供LTK。
  5. LL B收到LTK后，将使用LL_ENC_ RSP PDU响应LL A.
  6. LL A收到LL_ENC_ RSP PDU后，可以向LL B发送LL_START_ENC_REQ PDU，启用加密，LL B返回LL_START_ENC_RSP PDU。这两个PDU不携带任何参数。

加密开始后，双方可以安全通信。

协议数据包分析

cancelDiscovery

Inquiry Cancel
yaml 复制代码 
Bluetooth HCI Command - Inquiry Cancel
    Command Opcode: Inquiry Cancel (0x0402)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0000 0010 = Opcode Command Field: Inquiry Cancel (0x002)
    Parameter Total Length: 0
    [Response in frame: 248]
    [Command-Response Delta: 4.248ms]

对应的返回的Response：

yaml 复制代码 
Bluetooth HCI Event - Command Complete
    Event Code: Command Complete (0x0e)
    Parameter Total Length: 4
    Number of Allowed Command Packets: 1
    Command Opcode: Inquiry Cancel (0x0402)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0000 0010 = Opcode Command Field: Inquiry Cancel (0x002)
    Status: Success (0x00)
    [Command in frame: 247]
    [Command-Response Delta: 4.248ms]

createBond

yaml 复制代码 
Bluetooth HCI Command - Delete Stored Link Key
    Command Opcode: Delete Stored Link Key (0x0c12)
        0000 11.. .... .... = Opcode Group Field: Host Controller & Baseband Commands (0x03)
        .... ..00 0001 0010 = Opcode Command Field: Delete Stored Link Key (0x012)
    Parameter Total Length: 7
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)
    Delete All Flag: Delete only Link Key for specified BD_ADDR (0x00)
    [Response in frame: 250]
    [Command-Response Delta: 1.239ms]

该指令用于删除存放在蓝牙控制器中的单个或多个密钥；

  • Link Key：密钥用于设备间连接时认证鉴权并加密相互交互的数据，使得蓝牙技术更具有安全行；

返回对应的Response，Status = Success；

Remote Name Request
yaml 复制代码 
Bluetooth HCI Command - Remote Name Request
    Command Opcode: Remote Name Request (0x0419)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0001 1001 = Opcode Command Field: Remote Name Request (0x019)
    Parameter Total Length: 10
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)
    Page Scan Repetition Mode: R1 (0x01)
    Page Scan Mode: Mandatory Page Scan Mode (0x00)
    .001 0000 1101 0100 = Clock Offset: 0x10d4 (5385 msec)
    1... .... .... .... = Clock_Offset_Valid_Flag: true (1)
    [Pending in frame: 252]
    [Command-Pending Delta: 1.605ms]
    [Response in frame: 254]
    [Command-Response Delta: 205.412ms]
  • BD_ADDR：指定要获取Remote Device Name的Address；

返回对应执行发送完成的Response，Status = Success；

Controller对应该执行，会返回或者响应两个HCI Event：

  • Remote Host Supported Features Notification
  • Remote Name Request Complete
Remote Host Supported Features Notification
yaml 复制代码 
Bluetooth HCI Event - Remote Host Supported Features Notification
    Event Code: Remote Host Supported Features Notification (0x3d)
    Parameter Total Length: 14
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)
    LMP Features
        .... ...1 = 3-slot packets: True
        .... ..1. = 5-slot packets: True
        .... .1.. = Encryption: True
        .... 1... = Slot Offset: True
        ...0 .... = Timing Accuracy: False
        ..0. .... = Role Switch: False
        .0.. .... = Hold Mode: False
        0... .... = Sniff Mode: False
        .... ...0 = Park Mode: False
        .... ..0. = Power Control Requests: False
        .... .0.. = Channel Quality Driven Data Rate: False
        .... 0... = SCO Link: False
        ...0 .... = HV2 packets: False
        ..0. .... = HV3 packets: False
        .0.. .... = u-law Log Synchronous Data: False
        0... .... = A-law Log Synchronous Data: False
        .... ...0 = CVSD Synchronous Data: False
        .... ..0. = Paging Parameter Negotiation: False
        .... .0.. = Power Control: False
        .... 0... = Transparent Synchronous Data: False
        .000 .... = Flow Control Lag: 0 (0 bytes)
        0... .... = Broadband Encryption: False
        .... ...0 = Reserved: False
        .... ..0. = EDR ACL 2 Mbps Mode: False
        .... .0.. = EDR ACL 3 Mbps Mode: False
        .... 0... = Enhanced Inquiry Scan: False
        ...0 .... = Interlaced Inquiry Scan: False
        ..0. .... = Interlaced Page Scan: False
        .0.. .... = RSSI with Inquiry Results: False
        0... .... = EV3 Packets: False
        .... ...0 = EV4 Packets: False
        .... ..0. = EV5 Packets: False
        .... .0.. = Reserved: False
        .... 0... = AFH Capable Slave: False
        ...0 .... = AFH Classification Slave: False
        ..0. .... = BR/EDR Not Supported: False
        .0.. .... = LE Supported Controller: False
        0... .... = 3-slot EDR ACL packets: False
        .... ...0 = 5-slot EDR ACL packets: False
        .... ..0. = Sniff Subrating: False
        .... .0.. = Pause Encryption: False
        .... 0... = AFH Capable Master: False
        ...0 .... = AFH Classification Master: False
        ..0. .... = EDR eSCO 2 Mbps Mode: False
        .0.. .... = EDR eSCO 3 Mbps Mode: False
        0... .... = 3-slot EDR eSCO Packets: False
        .... ...0 = Extended Inquiry Response: False
        .... ..0. = Simultaneous LE and BR/EDR to Same Device Capable Controller: False
        .... .0.. = Reserved: False
        .... 0... = Secure Simple Pairing: False
        ...0 .... = Encapsulated PDU: False
        ..0. .... = Erroneous Data Reporting: False
        .0.. .... = Non-flushable Packet Boundary Flag: False
        0... .... = Reserved: False
        .... ...0 = Link Supervision Timeout Changed Event: False
        .... ..0. = Inquiry TX Power Level: False
        .... .0.. = Enhanced Power Control: False
        .000 0... = Reserved: False
        0... .... = Extended Features: False
  • BD_ADDR = HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)：对应的Remote Device Address；
  • LMP Features：Remote Device 支持的LMP 功能列表；
Remote Name Request Complete
less 复制代码 
Bluetooth HCI Event - Remote Name Request Complete
    Event Code: Remote Name Request Complete (0x07)
    Parameter Total Length: 255
    Status: Success (0x00)
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)
    Remote Name: dupz
    [Command in frame: 251]
    [Pending in frame: 252]
    [Pending-Response Delta: 203.807ms]
    [Command-Response Delta: 205.412ms]
  • BD_ADDR = HuaweiDe_42:c7:dd：Remote Device Address；
  • Remote Name：远端设备名称；

Create ACL Connection

Create Connection
yaml 复制代码 
Bluetooth HCI Command - Create Connection
    Command Opcode: Create Connection (0x0405)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0000 0101 = Opcode Command Field: Create Connection (0x005)
    Parameter Total Length: 13
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)
    Packet Type: 0xcc18, DH5, DM5, DH3, DM3, DH1, DM1
        1... .... .... .... = DH5: True
        .1.. .... .... .... = DM5: True
        ..0. .... .... .... = 3-DH5: False
        ...0 .... .... .... = 2-DH5: False
        .... 1... .... .... = DH3: True
        .... .1.. .... .... = DM3: True
        .... ..0. .... .... = 3-DH3: False
        .... ...0 .... .... = 2-DH3: False
        .... .... 000. .... = Reserved: 0x0
        .... .... ...1 .... = DH1: True
        .... .... .... 1... = DM1: True
        .... .... .... .0.. = 3-DH1: False
        .... .... .... ..0. = 2-DH1: False
        .... .... .... ...0 = Reserved: False
    Page Scan Repetition Mode: R1 (0x01)
    Page Scan Mode: Mandatory Page Scan Mode (0x00)
    .001 0000 1101 0100 = Clock Offset: 0x10d4 (5385 msec)
    1... .... .... .... = Clock_Offset_Valid_Flag: true (1)
    Allow Role Switch: Local device may be master, or may become slave after accepting a master slave switch. (0x01)
    [Pending in frame: 256]
    [Command-Pending Delta: 1.125ms]
    [Response in frame: 257]
    [Command-Response Delta: 2016.177ms]

该指令用于按照指定的Remote Device Address创建ACL链路；

  • Packet Type：包类型，列出了Remote Device支持的不同的数据包类型；

针对Packet Type参数，涉及到了蓝牙基带分组的概念，基带分组至少包括：接入码、分组头、有效载荷；

  • 接入码用于同步、直流、载频泄漏偏置补偿标识；
  • 分组头包含链路信息，确保纠正较多的错误。

针对基带分组，也区分链路类型；

ACL分组

D(M|H)（1|3|5）,D代表数据分组，M代表用2/3比例的FEC的中等速率分组；H代表不使用纠错码的高速率分组；1、3、5分别代表分组所占用的时隙数目；

​

类型 有效载荷头/字节 用户有效载荷/字节 FEC CRC 对称最大速率/kbps 非对称速率/kbps
前向 后向
DM1 1 0~17 2/3 有 108.8 108.8 108.8
DH1 1 0~27 无 有 172.8 172.8 172.8
DM3 2 0~127 2/3 有 258.1 387.2 54.4
DH3 2 0~183 无 有 390.4 585.6 86.4
DM5 2 0~224 2/3 有 286.7 477.8 36.3
DH5 2 0~339 无 有 433.9 723.2 57.6
AUX1 1 0~29 无 无 185.6 185.6 185.6

​

SCO分组

HV(1|2|3)。HV代表高质量语言分组，1、2、3有效载荷所采用的纠错码方法。1为1/3比例FEC，设备2个时隙发送一个单时隙分组；2为2/3比例FEC，设备4个时隙发送一个单时隙分组；3为不使用纠错码，设备6个时隙发送一个单时隙分组；

​

类型 有效载荷头/字节 用户有效载荷/字节 FEC CRC 有效载荷长度 同步速率/kbps 占用Tsco数目/语音长度
HV1 无 10 1/3 240 bit 64 2/1.25ms
HV2 20 2/3 4/2.5ms
HV3 30 无 6/3.75ms
DV 1D 10+(0-9)D 2/3D 有D 64+57.6D

​

返回对应执行发送完成的Response，Status = Pending；

yaml 复制代码 
Bluetooth HCI Event - Connect Complete
    Event Code: Connect Complete (0x03)
    Parameter Total Length: 11
    Status: Success (0x00)
    Connection Handle: 0x0003
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)
    Link Type: ACL connection (Data Channels) (0x01)
    Encryption Mode: Encryption Disabled (0x00)
    [Command in frame: 255]
    [Pending in frame: 256]
    [Pending-Response Delta: 2015.052ms]
    [Command-Response Delta: 2016.177ms]

Controller响应Create Connection指令后向上层上报了Connect Complete事件；

  • Status：Success；
  • Connection Handle：0x0003，连接句柄，表示本地设备和远端设备之间的ACL连接；
  • BD_ADDR：HuaweiDe_42:c7:dd
  • Link Type：ACL connection (Data Channels)
  • Encryption Mode：加密禁用
Read Clock offset
yaml 复制代码 
Bluetooth HCI Command - Read Clock offset
    Command Opcode: Read Clock offset (0x041f)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0001 1111 = Opcode Command Field: Read Clock offset (0x01f)
    Parameter Total Length: 2
    Connection Handle: 0x0003
    [Pending in frame: 260]
    [Command-Pending Delta: 1.203ms]
    [Response in frame: 277]
    [Command-Response Delta: 72.224ms]
  • Connection Handle：操作句柄，该句柄为ACL Connection Success时生成的Handle；

返回对应执行发送完成的Response，Status = Pending，意为等待状态，该状态代表了指令已经发送成功，但是Controller还未响应该指令的HCI_EVENT；

yaml 复制代码 
Bluetooth HCI Event - Read Clock Offset Complete
    Event Code: Read Clock Offset Complete (0x1c)
    Parameter Total Length: 5
    Status: Success (0x00)
    Connection Handle: 0x0003
    .001 0000 1101 0110 = Clock Offset: 0x10d6 (5387.5 ms)
    [Command in frame: 258]
    [Pending in frame: 260]
    [Pending-Response Delta: 71.021ms]
    [Command-Response Delta: 72.224ms]
  • Clock Offset：表示master和slave之间的clock的偏差，有了这个值可以加快master和slave之间page的时间；
Read Remote Version Information
yaml 复制代码 
Bluetooth HCI Command - Read Remote Version Information
    Command Opcode: Read Remote Version Information (0x041d)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0001 1101 = Opcode Command Field: Read Remote Version Information (0x01d)
    Parameter Total Length: 2
    Connection Handle: 0x0003
    [Pending in frame: 262]
    [Command-Pending Delta: 0.622ms]
    [Response in frame: 278]
    [Command-Response Delta: 73.542ms]

该指令用于读取Remote Device 的 Controller的版本信息；

返回对应执行发送完成的Response，Status = Pending；

yaml 复制代码 
Bluetooth HCI Event - Read Remote Version Information Complete
    Event Code: Read Remote Version Information Complete (0x0c)
    Parameter Total Length: 8
    Status: Success (0x00)
    Connection Handle: 0x0003
    LMP Version: 5.1 (0x0a)
    Manufacturer Name: HiSilicon Technologies Col, Ltd. (0x010f)
    LMP Subversion: 33561
    [Command in frame: 261]
    [Pending in frame: 262]
    [Pending-Response Delta: 72.92ms]
    [Command-Response Delta: 73.542ms]
  • LMP Version：LMP版本号；
  • Manufacturer Nam = HiSilicon Technologies Col, Ltd：生产商名称，深圳市海思半导体有限公司；
  • LMP Subversion：用于识别不同的芯片组；
LMP

LMP（Link Manager Protocol）：链路管理协议，通常被用来控制和协商两个设备之间的蓝牙连接操作，其中包括配置和控制逻辑传输、逻辑链路、物理链路；

LMP被用于两个LM（Link Manager）之前的交流。所有的LMP消息仅适用于发送和接收设备之间的物理链路、相关逻辑链路和逻辑传输；

yaml 复制代码 
Bluetooth HCI Command - Write Link Policy Settings
    Command Opcode: Write Link Policy Settings (0x080d)
        0000 10.. .... .... = Opcode Group Field: Link Policy Commands (0x02)
        .... ..00 0000 1101 = Opcode Command Field: Write Link Policy Settings (0x00d)
    Parameter Total Length: 4
    Connection Handle: 0x0003
    .... .... .... ...1 = Enable Master Slave Switch: true (1)
    .... .... .... ..1. = Enable Hold Mode: true (1)
    .... .... .... .1.. = Enable Sniff Mode: true (1)
    .... .... .... 0... = Enable Park Mode: false (0)
    [Response in frame: 267]
    [Command-Response Delta: 0.706ms]

该指令用于设置当前连线的连接策略；

该指令在发送了Authentication Requested指令之后执行的，无需等待Authentication指令的响应。而且在bluedroid enable的过程中，执行过 Write Default Link Policy Settings指令，用于向Controller写入默认的连接策略，这两个阶段的连接策略配置一致；

  • Enable Master Slave Switch：支持主设备/从设备开关；
  • Enable Hold Mode：保持模式；
  • Enable Sniff Mode：呼吸模式；
  • Enable Park Mode：休眠模式；

返回对应执行发送完成的Response，Status = Success；

yaml 复制代码 
Bluetooth HCI Command - Write Link Supervision Timeout
    Command Opcode: Write Link Supervision Timeout (0x0c37)
        0000 11.. .... .... = Opcode Group Field: Host Controller & Baseband Commands (0x03)
        .... ..00 0011 0111 = Opcode Command Field: Write Link Supervision Timeout (0x037)
    Parameter Total Length: 4
    Connection Handle: 0x0003
    Timeout: 8000 slots (5000 msec)
    [Response in frame: 269]
    [Command-Response Delta: 0.659ms]

改命令用于设置Link Supervision timeout（也就是Link lost时间）监控；

  • Timeout：8000 时隙，即5000 ms；

返回对应执行发送完成的Response，Status = Success；

Start Authentication

Authentication Requested

该指令的操作是在Link Key Settings之前就发送了，但是响应Response却是在一段时间之后，不是立马响应；

yaml 复制代码 
Bluetooth HCI Command - Authentication Requested
    Command Opcode: Authentication Requested (0x0411)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0001 0001 = Opcode Command Field: Authentication Requested (0x011)
    Parameter Total Length: 2
    Connection Handle: 0x0003
    [Pending in frame: 264]
    [Command-Pending Delta: 0.804ms]
    [Response in frame: 313]
    [Command-Response Delta: 3206.621ms]

该指令用于指令连接句柄的两个蓝牙地址进行身份认证；

返回对应执行发送完成的Response，Status = Pending；

最后通过Authentication Complete事件返回Authentication Requested的结果，Status = Success，在Command和Event之间有一段响应时间，在该时间段内，Controller和Host还执行了一些操作；

yaml 复制代码 
Bluetooth HCI Command - Link Key Request Negative Reply
    Command Opcode: Link Key Request Negative Reply (0x040c)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0000 1100 = Opcode Command Field: Link Key Request Negative Reply (0x00c)
    Parameter Total Length: 6
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)
    [Response in frame: 271]
    [Command-Response Delta: 0.643ms]

该指令的发送已经处于 Start Authentication 阶段了；

该指令用于如果host没有对应BD_ADDR的Link Key，host需要使用Link_Key_Request_Negative_Reply进行回复；该指令主要用于发起SSP。对应的还有一种情况：Host向Controller发送Link Key Request Reply执行，则直接进行Authentication；

  • SSP：该场景是在Host没有Remote Device LinkKey的情况下触发，即在这之前没有进行配对过或者是配对已取消，这时双发会发起PIN码确认弹窗；
  • Authentication：授权，无论是哪种Link Key Request，最终都会走到这一步，这个需要是进行双端授权动作，可以理解为匹配；

SSP会依赖于设备IO特性，查看设备是否支持输入输出。IO设备有四大类：仅显示无法输入、即可显示又可选择YesNo、仅可输入无法显示、无输入输出；

返回对应执行发送完成的Response，Status = Success；

IO Capability Request
less 复制代码 
Bluetooth HCI Event - IO Capability Request
    Event Code: IO Capability Request (0x31)
    Parameter Total Length: 6
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)

IO capability请求事件，可以理解为蓝牙用户请求配对事件；

IO Capability Request Reply
yaml 复制代码 
Bluetooth HCI Command - IO Capability Request Reply
    Command Opcode: IO Capability Request Reply (0x042b)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0010 1011 = Opcode Command Field: IO Capability Request Reply (0x02b)
    Parameter Total Length: 9
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)
    IO Capability: Display Yes/No (1)
    OOB Data Present: OOB Authentication Data Not Present (0)
    Authentication Requirements: MITM Protection Required - Dedicated Bonding. Use IO Capabilty To Determine Procedure, No Secure Connection (3)
    [Response in frame: 274]
    [Command-Response Delta: 0.706ms]

该命令用于当在SSP配对模式下，响应芯片IO capability的请求；

  • IO Capability：IO设备特性
Value Parameter Description Desc
0x00 DisplayOnly 仅显示无法输入
0x01 DisplayYesNo 即可显示又可选择YesNo
0x02 KeyboardOnly 仅可输入无法显示
0x03 NoInputNoOutput 无输入输出
0x04 - 0xFF Reserved for future use 保留
  • OOB Data Present：OOB（out-of-band），定义在指示OOB身份验证数据是否可用时使用的值，传输层协议使用带外数据(out-of-band,OOB)来发送一些重要的数据，如果通信一方有重要的数据需要通知对方时，协议能够将这些数据快速地发送到对方。为了发送这些数据，协议一般不使用与普通数据相同的通道，而是使用另外的通道；
Value Parameter Description Desc
0x00 OOB Authentication data not present OOB认证数据不存在
0x01 OOB Authentication data from remote device present 接收OOB数据
0x02 to 0xFF Reserved for future use 保留

如果在IO Capabilty Request event中已经收到来自BD_ADDR设备的OOB认证数据，则OOB_Data_Present应该设置为：0x01，否则如果在IO Capabilty Request event中没有收到来自BD_ADDR设备的OOB认证数据，则OOB_Data_Present应该设置为0x00；

  • Authentication Requirements：身份验证需求
Value Parameter Description Desc
0x00 MITM Protection Not Required -- No Bonding. Numeric comparison with automatic accept allowed. MITM保护不需要-不需要绑定。允许自动接受的数值比较
0x01 MITM Protection Required -- No Bonding. Use IO Capabilities to determine authentication procedure MITM保护---未绑定。使用IO能力来确定认证过程
0x02 MITM Protection Not Required -- Dedicated Bonding. Numeric comparison with automatic accept allowed. MITM保护不需要-专用绑定。允许自动接受的数值比较
0x03 MITM Protection Required -- Dedicated Bonding. Use IO Capabilities to determine authentication procedure MITM保护需要-专用绑定。使用IO能力来确定认证过程
0x04 MITM Protection Not Required -- General Bonding. Numeric Comparison with automatic accept allowed. MITM保护不需要-一般绑定。允许自动接受的数值比较
0x05 MITM Protection Required -- General Bonding. Use IO capabilities to determine authentication procedure. MITM保护要求-一般Bonding功能。使用IO功能来确定身份验证过程
All other values Reserved for future use 保留

返回对应执行发送完成的Response，Status = Success；

Read Remote Supported Features
yaml 复制代码 
Bluetooth HCI Command - Read Remote Supported Features
    Command Opcode: Read Remote Supported Features (0x041b)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0001 1011 = Opcode Command Field: Read Remote Supported Features (0x01b)
    Parameter Total Length: 2
    Connection Handle: 0x0003
    [Pending in frame: 282]
    [Command-Pending Delta: 0.724ms]
    [Response in frame: 293]
    [Command-Response Delta: 581.252ms]

该指令用于读取远程设备Controller所支持的一些功能；

返回对应执行发送完成的Response，Status = Pending；

yaml 复制代码 
Bluetooth HCI Event - Read Remote Supported Features
    Event Code: Read Remote Supported Features (0x0b)
    Parameter Total Length: 11
    Status: Success (0x00)
    Connection Handle: 0x0003
    LMP Features
        .... ...1 = 3-slot packets: True
        .... ..1. = 5-slot packets: True
        .... .1.. = Encryption: True
        .... 1... = Slot Offset: True
        ...1 .... = Timing Accuracy: True
        ..1. .... = Role Switch: True
        .0.. .... = Hold Mode: False
        1... .... = Sniff Mode: True
        .... ...0 = Park Mode: False
        .... ..1. = Power Control Requests: True
        .... .1.. = Channel Quality Driven Data Rate: True
        .... 1... = SCO Link: True
        ...1 .... = HV2 packets: True
        ..1. .... = HV3 packets: True
        .1.. .... = u-law Log Synchronous Data: True
        1... .... = A-law Log Synchronous Data: True
        .... ...1 = CVSD Synchronous Data: True
        .... ..1. = Paging Parameter Negotiation: True
        .... .1.. = Power Control: True
        .... 1... = Transparent Synchronous Data: True
        .100 .... = Flow Control Lag: 4 (1024 bytes)
        0... .... = Broadband Encryption: False
        .... ...0 = Reserved: False
        .... ..1. = EDR ACL 2 Mbps Mode: True
        .... .1.. = EDR ACL 3 Mbps Mode: True
        .... 1... = Enhanced Inquiry Scan: True
        ...1 .... = Interlaced Inquiry Scan: True
        ..1. .... = Interlaced Page Scan: True
        .1.. .... = RSSI with Inquiry Results: True
        1... .... = EV3 Packets: True
        .... ...1 = EV4 Packets: True
        .... ..1. = EV5 Packets: True
        .... .0.. = Reserved: False
        .... 1... = AFH Capable Slave: True
        ...1 .... = AFH Classification Slave: True
        ..0. .... = BR/EDR Not Supported: False
        .1.. .... = LE Supported Controller: True
        1... .... = 3-slot EDR ACL packets: True
        .... ...1 = 5-slot EDR ACL packets: True
        .... ..1. = Sniff Subrating: True
        .... .1.. = Pause Encryption: True
        .... 1... = AFH Capable Master: True
        ...1 .... = AFH Classification Master: True
        ..1. .... = EDR eSCO 2 Mbps Mode: True
        .1.. .... = EDR eSCO 3 Mbps Mode: True
        1... .... = 3-slot EDR eSCO Packets: True
        .... ...1 = Extended Inquiry Response: True
        .... ..1. = Simultaneous LE and BR/EDR to Same Device Capable Controller: True
        .... .0.. = Reserved: False
        .... 1... = Secure Simple Pairing: True
        ...1 .... = Encapsulated PDU: True
        ..0. .... = Erroneous Data Reporting: False
        .1.. .... = Non-flushable Packet Boundary Flag: True
        0... .... = Reserved: False
        .... ...1 = Link Supervision Timeout Changed Event: True
        .... ..1. = Inquiry TX Power Level: True
        .... .1.. = Enhanced Power Control: True
        .000 0... = Reserved: False
        1... .... = Extended Features: True
    [Command in frame: 279]
    [Pending in frame: 282]
    [Pending-Response Delta: 580.528ms]
    [Command-Response Delta: 581.252ms]

该Event可以Remote Host Supported Features Notification event进行比较，当所出状态不同时，该阶段支持的LMP Feature不同；

Read Remote Extended Features
yaml 复制代码 
Bluetooth HCI Command - Read Remote Extended Features
    Command Opcode: Read Remote Extended Features (0x041c)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0001 1100 = Opcode Command Field: Read Remote Extended Features (0x01c)
    Parameter Total Length: 3
    Connection Handle: 0x0003
    Page Number: 1
    [Pending in frame: 295]
    [Command-Pending Delta: 2.212ms]
    [Response in frame: 296]
    [Command-Response Delta: 80.604ms]

该指令用于读取远程设备Controller的扩展功能，是一些非必须的可选功能，比如是否支持BR/EDR和LE，是否支持SSP等；

  • Page Number：如果是0x00表示获取一般的LMP features，跟Read Remote Supported Features Command功能是一样的，0x01-0xFF表示获取对应页的LMP extended features。当前读取的是第一页的内容；

返回对应执行发送完成的Response，Status = Pending；

结束后可以接收到HCI_Read_Remote_Extended_Features_Complete事件通知；

Page 1
yaml 复制代码 
Bluetooth HCI Event - Read Remote Extended Features Complete
    Event Code: Read Remote Extended Features Complete (0x23)
    Parameter Total Length: 13
    Status: Success (0x00)
    Connection Handle: 0x0003
    Page Number: 1
    Max. Page Number: 2
    LMP Features
        .... ...1 = Secure Simple Pairing Host: True
        .... ..1. = LE Supported Host: True
        .... .1.. = Simultaneous LE and BR/EDR to Same Device Capable Host: True
        .... 1... = Secure Connections Host: True
        0000 .... = Reserved: 0x0
        Reserved: 00000000000000
    [Command in frame: 294]
    [Pending in frame: 295]
    [Pending-Response Delta: 78.392ms]
    [Command-Response Delta: 80.604ms]
Page 2

这个是对应Page Number = 2的Request 对应的Response；

yaml 复制代码 
Bluetooth HCI Event - Read Remote Extended Features Complete
    Event Code: Read Remote Extended Features Complete (0x23)
    Parameter Total Length: 13
    Status: Success (0x00)
    Connection Handle: 0x0003
    Page Number: 2
    Max. Page Number: 2
    LMP Features
        .... ...0 = Connectionless Slave Broadcast Master Operation: False
        .... ..0. = Connectionless Slave Broadcast Slave Operation: False
        .... .0.. = Synchronization Train: False
        .... 0... = Synchronization Scan: False
        ...1 .... = Inquiry Response Notification Event: True
        ..0. .... = Generalized Interlaced Scan: False
        .0.. .... = Coarse Clock Adjustment: False
        0... .... = Reserved: False
        .... ...1 = Secure Connections Controller: True
        .... ..1. = Ping: True
        .... .0.. = Reserved: False
        .... 0... = Train Nudging: False
        ...0 .... = Slot Availability Mask: False
        Reserved: 000000000000
    [Command in frame: 297]
    [Pending in frame: 298]
    [Pending-Response Delta: 53.795ms]
    [Command-Response Delta: 54.728ms]
Change Connection Packet Type
yaml 复制代码 
Frame 300: 8 bytes on wire (64 bits), 8 bytes captured (64 bits)
Bluetooth
Bluetooth HCI H4
Bluetooth HCI Command - Change Connection Packet Type
    Command Opcode: Change Connection Packet Type (0x040f)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0000 1111 = Opcode Command Field: Change Connection Packet Type (0x00f)
    Parameter Total Length: 4
    Connection Handle: 0x0003
    Packet Type: 0xcc18, DH5, DM5, DH3, DM3, DH1, DM1
        1... .... .... .... = DH5: True
        .1.. .... .... .... = DM5: True
        ..0. .... .... .... = 3-DH5: False
        ...0 .... .... .... = 2-DH5: False
        .... 1... .... .... = DH3: True
        .... .1.. .... .... = DM3: True
        .... ..0. .... .... = 3-DH3: False
        .... ...0 .... .... = 2-DH3: False
        .... .... 000. .... = Reserved: 0x0
        .... .... ...1 .... = DH1: True
        .... .... .... 1... = DM1: True
        .... .... .... .0.. = 3-DH1: False
        .... .... .... ..0. = 2-DH1: False
        .... .... .... ...0 = Reserved: False
    [Pending in frame: 303]
    [Command-Pending Delta: 1.543ms]
    [Response in frame: 305]
    [Command-Response Delta: 3.552ms]
​

该指令用于动态的修改一个已建立使用的Packet types；

返回对应执行发送完成的Response，Status = Pending；

yaml 复制代码 
Bluetooth HCI Event - Connection Packet Type Changed
    Event Code: Connection Packet Type Changed (0x1d)
    Parameter Total Length: 5
    Status: Success (0x00)
    Connection Handle: 0x0003
    Packet Type for ACL: 0xcc18, DH5 may be used, DM5 may be used, DH3 may be used, DM3 may be used, DH1 may be used, DM1 may be used
        1... .... .... .... = DH5 may be used: True
        .1.. .... .... .... = DM5 may be used: True
        ..0. .... .... .... = 3-DH5 shall NOT be used: False
        ...0 .... .... .... = 2-DH5 shall NOT be used: False
        .... 1... .... .... = DH3 may be used: True
        .... .1.. .... .... = DM3 may be used: True
        .... ..0. .... .... = 3-DH3 shall NOT be used: False
        .... ...0 .... .... = 2-DH3 shall NOT be used: False
        .... .... 000. .... = Reserved: 0x0
        .... .... ...1 .... = DH1 may be used: True
        .... .... .... 1... = DM1 may be used: True
        .... .... .... .0.. = 3-DH1 shall NOT be used: False
        .... .... .... ..0. = 2-DH1 shall NOT be used: False
        .... .... .... ...0 = Reserved: False
    [Command in frame: 300]
    [Pending in frame: 303]
    [Pending-Response Delta: 2.009ms]
    [Command-Response Delta: 3.552ms]
User Confirmation Request Reply
yaml 复制代码 
Bluetooth HCI Command - User Confirmation Request Reply
    Command Opcode: User Confirmation Request Reply (0x042c)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0010 1100 = Opcode Command Field: User Confirmation Request Reply (0x02c)
    Parameter Total Length: 6
    BD_ADDR: HuaweiDe_42:c7:dd (30:aa:e4:42:c7:dd)
    [Response in frame: 310]
    [Command-Response Delta: 1.208ms]

该指令用于蓝牙用户请求，可以简单的理解为PIN码确认弹窗；

返回对应执行发送完成的Response，Status = Success；

Set Encryption

直到协议栈接收到Authentication Complete Event之后，我们就可以开始Set Encryption，当加密改变时，所以的与远端设备所有的ACL通信都会关闭；

Set Connection Encryption
yaml 复制代码 
Bluetooth HCI Command - Set Connection Encryption
    Command Opcode: Set Connection Encryption (0x0413)
        0000 01.. .... .... = Opcode Group Field: Link Control Commands (0x01)
        .... ..00 0001 0011 = Opcode Command Field: Set Connection Encryption (0x013)
    Parameter Total Length: 3
    Connection Handle: 0x0003
    Encryption Enable: Link Level Encryption is ON (0x01)
    [Pending in frame: 315]
    [Command-Pending Delta: 0.523ms]
    [Response in frame: 316]
    [Command-Response Delta: 19.245ms]

该指令用于设置enable/disable连接层的加密

  • Encryption Enable：加密状态

    • 0x00：表示Turn Link Level Encryption OFF（关闭连接层加密）
    • 0x01：表示Turn Link Level Encryption ON（开启连接层加密）

当本地和远端设备都支持Secure Connections (Controller Support)和Secure Connections (Host Support) features时，如果Connection_Handle的加密是enable，此时设置Encryption_Enable为Turn Link Level Encryption OFF，controller会报错：Encryption Mode Not Acceptable (0x25).

返回对应执行发送完成的Response，Status = Pending；

yaml 复制代码 
Bluetooth HCI Event - Encryption Change
    Event Code: Encryption Change (0x08)
    Parameter Total Length: 4
    Status: Success (0x00)
    Connection Handle: 0x0003
    Encryption Enable: Unknown (0x02)
    [Command in frame: 314]
    [Pending in frame: 315]
    [Pending-Response Delta: 18.722ms]
    [Command-Response Delta: 19.245ms]

在实际的Response过程中返回了0x0003，意为Unknown； （这个问题后续确认一下。）

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