Documentation
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Overview ¶
Package att decodes the Bluetooth Attribute Protocol (ATT, Core spec Vol 3 Part F) — the request/response protocol behind GATT, carried on L2CAP CID 0x0004. ATT is the application layer of BLE: it is how a client reads and writes a server's attributes (characteristics), discovers its services, and receives notifications. Decoding ATT traffic from a btsnoop / HCI-ACL capture is the recon headline for what a BLE app actually does on a device: which attribute **handles** it reads and writes, the **service / characteristic discovery** (Read By Group Type / Read By Type / Find Information) that maps the GATT database, and the **notifications / indications** a device pushes. It is the final layer of the project's Bluetooth-stack decode chain (bt_hci_decode → bt_l2cap_decode → here) and pairs with the UUID naming in bluetooth_gatt_uuid_lookup.
Wrap-vs-native judgement ¶
Native. An ATT PDU is a 1-byte opcode then per-opcode fixed fields — little-endian 16-bit handles, a 16-bit MTU, 2-or-16-byte UUIDs, and value blobs. A byte read + an opcode dispatch + handle/UUID reads; stdlib only, no new go.mod dep.
Verifiable / no confidently-wrong output ¶
The ATT opcodes, the error codes and the per-opcode field layouts follow the Bluetooth Core specification (Vol 3 Part F) — deterministic and byte-checkable. The common opcodes (Error/Exchange MTU/Find Information/ Read By Type/Read/Read By Group Type/Write/Notification/Indication) are field-decoded; the attribute VALUE blobs are surfaced as raw hex (their contents are characteristic-specific), and the length-prefixed attribute-data lists (discovery responses) are surfaced raw with their per-record length noted. An opcode outside the decoded set is named (or reported by value) with its body raw.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type Result ¶
type Result struct {
Opcode int `json:"opcode"`
OpcodeHex string `json:"opcode_hex"`
Operation string `json:"operation"`
Handle string `json:"handle,omitempty"`
StartHandle string `json:"start_handle,omitempty"`
EndHandle string `json:"end_handle,omitempty"`
UUID string `json:"uuid,omitempty"`
MTU *int `json:"mtu,omitempty"`
ValueHex string `json:"value_hex,omitempty"`
// Error Response
RequestOpcode string `json:"request_opcode,omitempty"`
ErrorCode string `json:"error_code,omitempty"`
// Discovery responses (length-prefixed attribute-data lists)
RecordLength *int `json:"record_length,omitempty"`
PayloadHex string `json:"payload_hex,omitempty"`
Notes []string `json:"notes,omitempty"`
}
Result is the decoded view of an ATT PDU.
Source Files