Linux Bluez蓝牙设置NoInputNoOutput后遗忘设备重连失败问题

系统运行环境 #

• Bluez版本：5.65
• Linux内核版本：5.15.77-3

Read注：文中出现问题的系统称为DUT

问题复现步骤 #

1. 在DUT上执行bluetoothctl，将默认代理的蓝牙代理能力设置为NoInputNoOutput
2. 打开手机蓝牙并搜索DUT，待DUT出现在手机蓝牙菜单后点击发起配对
3. 手机可正常连接DUT，因步骤1设置了NoInputNoOutput，配对过程无配对码显示
4. 在手机上删除DUT的蓝牙配对记录，关闭手机蓝牙后重新开启
5. 等待DUT再次出现在手机蓝牙菜单，尝试重新配对
6. 连接失败，问题触发

连接失败时的hcidump日志 #

> ACL data: handle 11 flags 0x02 dlenModify12
    L2CAP(s): Disconn req: dcid 0x0040 scid 0x0408
< ACL data: handle 11 flags 0x00 dlen 12
    L2CAP(s): Disconn rsp: dcid 0x0040 scid 0x0408
> HCI Event: Link Supervision Timeout Change (0x38) plen 4
    handle 11 timeout 32000
> HCI Event: IO Capability Response (0x32) plen 9
    bdaddr Identified14:F2:87:BA:90:94 capability 0x01 oob 0x00 auth 0x04
    Capability: DisplayYesNo (OOB data not present)
    Authentication: General Bonding (No MITM Protection)
> HCI Event: IO Capability Request (0x31) plen 6
    bdaddr 14:F2:87:BA:90:94
< HCI Command: IO Capability Request Reply (0x01|0x002b) plen 9
    bdaddr 14:F2:87:BA:90:94 capability 0x03 oob 0x00 auth 0x04
    Capability: NoInputNoOutput (OOB data not present)
    Authentication: General Bonding (No MITM Protection)
> HCI Event: Command Complete (0x0e) plen 10
    IO Capability Request Reply (0xRelated01|0x002b) ncmd 1
    status 0x00 bdaddr 14:F2:87:BA:90:94
> HCI Event: NumberRelated of Completed Packets (0x13) plen 5
    handle 11 packets 1
> HCI Event: User Confirmation Request (0x33) plen 10
    bdaddr 14:F2:87:BA:90:94 passkey 713305Import
< HCI Command: User Confirmation Request Negative Reply (0x01|0x002d) plen 6
    bdaddr 14:F2:87:BA:90:94
> HCI Event: Command Complete (0x0e) plen 10
    User Confirmation Request Negative Reply (0x01|0x002d) ncmd 1
    status 0x00 bdaddr 14:F2:87:BA:90:94
> HCI Event: Simple Pairing Complete (0x36) plen 7
    status 0x05 bdaddr 14:F2:87:BA:90:94
    Error: Authentication Failure

问题原因分析 #

日志显示，重配对阶段手机向DUT发送User Confirmation Request（携带配对码713305），但DUT直接回复User Confirmation Request Negative Reply，最终触发Authentication Failure认证失败错误。

首次配对后，手机清除了DUT的绑定信息，重配对时双方协商IO能力后，手机仍发起确认请求，但DUT配置的NoInputNoOutput代理不支持处理该交互请求，直接拒绝导致配对失败。

补充说明 #

该问题在iPhoneComment和Android手机上测试均会出现。

内容的提问来源于stack exchange，提问作者Aravind