BTSnoop/Monitor protocol formats

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Opcode definitions

New Index

Code:        0x0000
Parameters:  Type (1 Octet
         Bus (1 Octet)
         BD_Addr (6 Octets)
         Name (8 Octets)

This opcode indicates that a new controller instance with a
given index was added. With some protocols, like the TTY-based
one there is only a single supported controller, meaning the
index is implicitly 0.

Deleted Index

Code:        0x0001

This opcode indicates that the controller with a specific index
was removed.

Command Packet

Code:        0x0002

HCI command packet.

Event Packet

Code:        0x0003

HCI event packet.

ACL TX Packet

Code:        0x0004

Outgoing ACL packet.

ACL RX Packet

Code:        0x0005

Incoming ACL packet.

SCO TX Packet

Code:        0x0006

Outgoing SCO packet.

SCO RX Packet

Code:        0x0007

Incomnig SCO packet.

Open Index

Code:        0x0008

The HCI transport for the specified controller has been opened.

Close Index

Code:        0x0009

The HCI transport for the specified controller has been closed.

Index Information

Code:        0x000a
Parameters:  BD_Addr (6 Octets)
         Manufacturer (2 Octets)

Information about a specific controller.

Vendor Diagnostics

Code:        0x000b

Vendor diagnostic information.

System Note

Code:        0x000c

System note.

User Logging

Code:        0x000d
Parameters:  Priority (1 Octet)
         Ident_Length (1 Octet)
         Ident (Ident_Length Octets)

User logging information.

TTY-based protocol

This section covers the protocol that can be parsed by btmon when passing it the --tty parameter. The protocol is little endian, packet based, and has the following header for each packet:

struct tty_hdr { uint16_t data_len; uint16_t opcode; uint8_t flags; uint8_t hdr_len; uint8_t ext_hdr[0]; } attribute ((packed));

The actual payload starts at ext_hdr + hdr_len and has the length of data_len - 4 - hdr_len. Each field of the header is defined as follows:

data_len: This is the total length of the entire packet, excuding the data_len field itself.

opcode: The BTSnoop opcode

flags: Special flags for the packet. Currently no flags are defined.

hdr_len: Length of the extended header.

ext_hdr: This is a sequence of header extension fields formatted as:

struct {
    uint8_t type;
    uint8_t value[length];
}

The length of the value is dependent on the type. Currently the
following types are defined:

Type                 Length    Meaning
----------------------------------------------------------------
1  Command drops     1 byte    Dropped HCI command packets
2  Event drops       1 byte    Dropped HCI event packets
3  ACL TX drops      1 byte    Dropped ACL TX packets
4  ACL RX drops      1 byte    Dropped ACL RX packets
5  SCO TX drops      1 byte    Dropped SCO TX packets
6  SCO RX drops      1 byte    Dropped SCO RX packets
7  Other drops       1 byte    Dropped other packets
8  32-bit timestamp  4 bytes   Timestamp in 1/10th ms

The drops fields indicate the number of packets that the
implementation had to drop (e.g. due to lack of buffers) since
the last reported drop count.

The fields of the extended header must be sorted by increasing
type. This is essential so that unknown types can be ignored and
the parser can jump to processing the payload.