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//! Advertising channel operations. //! //! This module defines PDUs, states and fields used by packets transmitted on the advertising //! channels. Generally, this includes everything needed to advertise as and scan for slave devices //! and to establish connections. //! //! Note that while the types in here do not completely eliminate illegal values to be created, they //! do employ a range of sanity checks that prevent bogus packets from being sent by the stack. use { super::{ ad_structure::{AdStructure, Flags}, AddressKind, DeviceAddress, }, crate::{ bytes::*, phy::ChannelMap, time::Duration, utils::{Hex, HexSlice}, Error, }, byteorder::{ByteOrder, LittleEndian}, core::{fmt, iter}, }; /// CRC initialization value for advertising channel packets. /// /// Data channel packets use a preset shared when initiating the connection. /// /// (as with `CRC_POLY`, only the least significant 24 bits count) pub const CRC_PRESET: u32 = 0x00555555; /// Max. advertising PDU payload size in Bytes. /// /// Note that data channel PDUs can carry much larger payloads. pub const MAX_PAYLOAD_SIZE: usize = 37; /// Access Address to use for all advertising channel packets. pub const ACCESS_ADDRESS: u32 = 0x8E89BED6; /// A parsed advertising channel PDU. #[derive(Debug, Copy, Clone)] pub enum Pdu<'a> { /// Connectable and scannable advertisement. ConnectableUndirected { /// Address of the advertising device that is sending this PDU. advertiser_addr: DeviceAddress, /// AD structures sent along with the advertisement. advertising_data: BytesOr<'a, [AdStructure<'a>]>, }, /// Directed connectable advertisement sent to an initiator. /// /// Does not contain advertisement data. ConnectableDirected { /// Address of the advertising device that is sending this PDU. advertiser_addr: DeviceAddress, /// Intended receiver of the advertisement. initiator_addr: DeviceAddress, }, /// A non-connectable undirected advertisement (aka "beacon"). NonconnectableUndirected { /// Address of the advertising device (beacon) that is sending this PDU. advertiser_addr: DeviceAddress, /// AD structures sent along with the advertisement. advertising_data: BytesOr<'a, [AdStructure<'a>]>, }, /// Scannable advertisement. ScannableUndirected { /// Address of the advertising device that is sending this PDU. advertiser_addr: DeviceAddress, /// AD structures sent along with the advertisement. advertising_data: BytesOr<'a, [AdStructure<'a>]>, }, /// Scan request sent from a scanner to an advertising device. /// /// This can only be sent in response to an advertising PDU that indicates /// that the advertising device is scannable (`ConnectableUndirected` and /// `ScannableUndirected`). ScanRequest { /// Address of the scanning device sending this PDU. scanner_addr: DeviceAddress, /// Address of the advertising device that should be scanned. advertiser_addr: DeviceAddress, }, /// Response to a scan request, sent by the scanned advertising device. ScanResponse { /// Address of the advertising device that responds to a scan request by /// sending this PDU. advertiser_addr: DeviceAddress, /// Scan data payload, consisting of additional user-defined AD /// structures. scan_data: BytesOr<'a, [AdStructure<'a>]>, }, /// A request to establish a connection, sent by an initiating device. /// /// This may only be sent to an advertising device that has broadcast a /// connectable advertisement (`ConnectableUndirected` or /// `ConnectableDirected`). ConnectRequest { /// Address of the device initiating the connection by sending this PDU. initiator_addr: DeviceAddress, /// Address of the intended receiver of this packet. advertiser_addr: DeviceAddress, /// Connection parameters. lldata: ConnectRequestData, }, } impl<'a> Pdu<'a> { /// Constructs a PDU by parsing `payload`. pub fn from_header_and_payload( header: Header, payload: &mut ByteReader<'a>, ) -> Result<Self, Error> { use self::Pdu::*; if usize::from(header.payload_length()) != payload.bytes_left() { return Err(Error::InvalidLength); } Ok(match header.type_() { PduType::AdvInd => ConnectableUndirected { advertiser_addr: { let kind = if header.tx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, advertising_data: BytesOr::from_bytes(payload)?, }, PduType::AdvDirectInd => ConnectableDirected { advertiser_addr: { let kind = if header.tx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, initiator_addr: { let kind = if header.rx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, }, PduType::AdvNonconnInd => NonconnectableUndirected { advertiser_addr: { let kind = if header.tx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, advertising_data: BytesOr::from_bytes(payload)?, }, PduType::AdvScanInd => ScannableUndirected { advertiser_addr: { let kind = if header.tx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, advertising_data: BytesOr::from_bytes(payload)?, }, PduType::ScanReq => ScanRequest { scanner_addr: { // Scanning device sends this PDU let kind = if header.tx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, advertiser_addr: { // Advertiser receives this PDU (when it broadcasts an advertisement that // indicates that the device is scannable). let kind = if header.rx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, }, PduType::ScanRsp => ScanResponse { advertiser_addr: { let kind = if header.tx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, scan_data: BytesOr::from_bytes(payload)?, }, PduType::ConnectReq => ConnectRequest { // Initiator sends this PDU initiator_addr: { // Scanning device sends this PDU let kind = if header.tx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, // Advertiser receives this PDU (if it has sent a connectable advertisement) advertiser_addr: { // Advertiser receives this PDU (when it broadcasts an advertisement that // indicates that the device is scannable). let kind = if header.rx_add() { AddressKind::Random } else { AddressKind::Public }; DeviceAddress::new(payload.read_array::<[u8; 6]>()?, kind) }, lldata: ConnectRequestData::from_bytes(payload)?, }, PduType::Unknown(_) => return Err(Error::InvalidValue), }) } /// Returns the device address of the sender of this PDU. pub fn sender(&self) -> &DeviceAddress { use self::Pdu::*; match self { ConnectableUndirected { advertiser_addr, .. } | ConnectableDirected { advertiser_addr, .. } | NonconnectableUndirected { advertiser_addr, .. } | ScannableUndirected { advertiser_addr, .. } | ScanResponse { advertiser_addr, .. } => advertiser_addr, ScanRequest { scanner_addr, .. } => scanner_addr, ConnectRequest { initiator_addr, .. } => initiator_addr, } } /// Returns the intended receiver of this PDU. /// /// This may be `None` if the PDU doesn't have a fixed receiver. pub fn receiver(&self) -> Option<&DeviceAddress> { use self::Pdu::*; match self { ConnectableUndirected { .. } | NonconnectableUndirected { .. } | ScannableUndirected { .. } | ScanResponse { .. } => None, ConnectableDirected { initiator_addr, .. } => Some(initiator_addr), ScanRequest { advertiser_addr, .. } | ConnectRequest { advertiser_addr, .. } => Some(advertiser_addr), } } /// Returns the PDU type of `self`. pub fn ty(&self) -> PduType { use self::Pdu::*; match self { ConnectableUndirected { .. } => PduType::AdvInd, ConnectableDirected { .. } => PduType::AdvDirectInd, NonconnectableUndirected { .. } => PduType::AdvNonconnInd, ScannableUndirected { .. } => PduType::AdvScanInd, ScanRequest { .. } => PduType::ScanReq, ScanResponse { .. } => PduType::ScanRsp, ConnectRequest { .. } => PduType::ConnectReq, } } /// Returns an iterator over all AD structures encoded in the PDU. /// /// If this PDU doesn't support attaching AD structures, this will return /// `None`. pub fn advertising_data(&self) -> Option<impl Iterator<Item = AdStructure<'a>>> { use self::Pdu::*; match self { ConnectableUndirected { advertising_data, .. } | NonconnectableUndirected { advertising_data, .. } | ScannableUndirected { advertising_data, .. } => Some(advertising_data.iter()), ScanResponse { scan_data, .. } => Some(scan_data.iter()), ScanRequest { .. } | ConnectableDirected { .. } | ConnectRequest { .. } => None, } } } /// Decodes an advertising channel PDU (consisting of header and payload) from /// raw bytes. impl<'a> FromBytes<'a> for Pdu<'a> { fn from_bytes(bytes: &mut ByteReader<'a>) -> Result<Self, Error> { let header = Header::from_bytes(bytes)?; Self::from_header_and_payload(header, bytes) } } /// Connection parameters sent along with a `ConnectRequest` PDU (also known as /// `LLData`). #[derive(Copy, Clone, Debug)] pub struct ConnectRequestData { access_address: Hex<u32>, crc_init: Hex<u32>, /// Transmit window size in µs. win_size: Duration, /// Transmit window offset in µs. win_offset: Duration, /// Connection interval in µs. interval: Duration, /// Slave latency (number of connection events). latency: u16, /// Connection timeout. timeout: Duration, chm: ChannelMap, hop: u8, sca: SleepClockAccuracy, } impl ConnectRequestData { /// Returns the Access Address to use for data channel communication. /// /// The address is randomly generated by the initiator (the device sending the connection /// request) according to the requirements in the Bluetooth specification. pub fn access_address(&self) -> u32 { self.access_address.0 } /// Returns the initialization value for the CRC calculation. /// /// The CRC *polynomial* is always the same. pub fn crc_init(&self) -> u32 { self.crc_init.0 } /// Returns the channel map specified by the initiator. pub fn channel_map(&self) -> &ChannelMap { &self.chm } /// Returns the channel hop distance. /// /// This must be in range `5..=16`. pub fn hop(&self) -> u8 { self.hop } /// Returns the end of the transmit window from reception of the `CONNECT_REQ` containing /// `self`. pub fn end_of_tx_window(&self) -> Duration { self.win_offset + self.win_size + Duration::from_micros(1250) } /// Returns the connection event interval in µs. pub fn interval(&self) -> Duration { self.interval } /// Returns the slave latency (as the number of connection events). pub fn slave_latency(&self) -> u16 { self.latency } /// Returns the connection supervision timeout (`connSupervisionTimeout`) to use for this /// connection. /// /// If no data packet is received for this duration, the connection should be considered lost. pub fn supervision_timeout(&self) -> Duration { self.timeout } } impl FromBytes<'_> for ConnectRequestData { fn from_bytes(bytes: &mut ByteReader) -> Result<Self, Error> { let sca; Ok(Self { access_address: Hex(bytes.read_u32_le()?), crc_init: { let mut le_bytes = [0u8; 4]; le_bytes[..3].copy_from_slice(bytes.read_slice(3)?); Hex(u32::from_le_bytes(le_bytes)) }, // transmitWindowSize in 1.25 ms steps win_size: Duration::from_micros(u32::from(bytes.read_u8()?) * 1250), // transmitWindowOffset in 1.25 ms steps win_offset: Duration::from_micros(u32::from(bytes.read_u16_le()?) * 1250), // connInterval in 1.25 ms steps interval: Duration::from_micros(u32::from(bytes.read_u16_le()?) * 1250), // connSlaveLatency in no. of events latency: bytes.read_u16_le()?, // supervision timeout in 10 ms steps timeout: Duration::from_micros(u32::from(bytes.read_u16_le()?) * 10_000), chm: ChannelMap::from_raw(bytes.read_array()?), hop: { let hop_and_sca = bytes.read_u8()?; sca = (hop_and_sca >> 5) & 0b111; hop_and_sca & 0b11111 }, sca: { use self::SleepClockAccuracy::*; match sca { 0 => Ppm251To500, 1 => Ppm151To250, 2 => Ppm101To150, 3 => Ppm76To100, 4 => Ppm51To75, 5 => Ppm31To50, 6 => Ppm21To30, 7 => Ppm0To20, _ => unreachable!(), // only 3 bits } }, }) } } /// Indicates the master's sleep clock accuracy (SCA) in ppm (parts per /// million). /// /// The lower the PPM, the higher the accuracy. #[derive(Copy, Clone, Debug)] pub enum SleepClockAccuracy { Ppm251To500, Ppm151To250, Ppm101To150, Ppm76To100, Ppm51To75, Ppm31To50, Ppm21To30, Ppm0To20, } /// Stores an advertising channel PDU. /// /// This is an owned version of `Pdu` and should be used when *creating* a PDU /// to be sent out. pub struct PduBuf { /// 2-Byte header. header: Header, /// Fixed-size buffer that can store the largest PDU. Actual length is /// stored in the header. payload_buf: [u8; MAX_PAYLOAD_SIZE], } impl PduBuf { /// Builds a PDU buffer containing advertiser address and data. fn adv( ty: PduType, adv: DeviceAddress, adv_data: &mut Iterator<Item = &AdStructure>, ) -> Result<Self, Error> { let mut payload = [0; MAX_PAYLOAD_SIZE]; let mut buf = ByteWriter::new(&mut payload[..]); buf.write_slice(adv.raw()).unwrap(); for ad in adv_data { ad.to_bytes(&mut buf)?; } let left = buf.space_left(); let used = payload.len() - left; let mut header = Header::new(ty); header.set_payload_length(used as u8); header.set_tx_add(adv.is_random()); header.set_rx_add(false); Ok(Self { header, payload_buf: payload, }) } /// Creates a connectable undirected advertising PDU (`ADV_IND`). /// /// # Parameters /// /// * `adv`: The advertiser address, the address of the device sending this /// PDU. /// * `adv_data`: Additional advertising data to send. pub fn connectable_undirected( advertiser_addr: DeviceAddress, advertiser_data: &[AdStructure], ) -> Result<Self, Error> { Self::adv( PduType::AdvInd, advertiser_addr, &mut advertiser_data.iter(), ) } /// Creates a connectable directed advertising PDU (`ADV_DIRECT_IND`). pub fn connectable_directed( advertiser_addr: DeviceAddress, initiator_addr: DeviceAddress, ) -> Self { let mut payload = [0; 37]; payload[0..6].copy_from_slice(advertiser_addr.raw()); payload[6..12].copy_from_slice(initiator_addr.raw()); let mut header = Header::new(PduType::AdvDirectInd); header.set_payload_length(6 + 6); header.set_tx_add(advertiser_addr.is_random()); header.set_rx_add(initiator_addr.is_random()); Self { header, payload_buf: payload, } } /// Creates a non-connectable undirected advertising PDU /// (`ADV_NONCONN_IND`). /// /// This is equivalent to `PduBuf::beacon`, which should be preferred when /// building a beacon PDU to improve clarity. pub fn nonconnectable_undirected( advertiser_addr: DeviceAddress, advertiser_data: &[AdStructure], ) -> Result<Self, Error> { Self::adv( PduType::AdvNonconnInd, advertiser_addr, &mut advertiser_data.iter(), ) } /// Creates a scannable undirected advertising PDU (`ADV_SCAN_IND`). /// /// Note that scanning is not supported at the moment. pub fn scannable_undirected( advertiser_addr: DeviceAddress, advertiser_data: &[AdStructure], ) -> Result<Self, Error> { Self::adv( PduType::AdvScanInd, advertiser_addr, &mut advertiser_data.iter(), ) } /// Creates an advertising channel PDU suitable for building a simple /// beacon. /// /// This is mostly equivalent to `PduBuf::nonconnectable_undirected`, but it /// will automatically add a suitable `Flags` AD structure to the /// advertising data (this flags is mandatory). pub fn beacon( advertiser_addr: DeviceAddress, advertiser_data: &[AdStructure], ) -> Result<Self, Error> { Self::adv( PduType::AdvNonconnInd, advertiser_addr, &mut iter::once(&AdStructure::from(Flags::broadcast())).chain(advertiser_data), ) } /// Creates an advertising PDU that makes this device "visible" for scanning /// devices that want to establish a connection. /// /// This should be used when this device would like to initiate pairing. /// /// This function is mostly equivalent to `PduBuf::connectable_undirected`, /// but will automatically add a suitable `Flags` AD structure to the /// advertising data. /// /// To establish a connection with an already paired device, a "directed" /// advertisement must be sent instead. pub fn discoverable( advertiser_addr: DeviceAddress, advertiser_data: &[AdStructure], ) -> Result<Self, Error> { // TODO what's the difference between "general" and "limited" discoverability? Self::adv( PduType::AdvInd, advertiser_addr, &mut iter::once(&AdStructure::from(Flags::discoverable())).chain(advertiser_data), ) } /// Creates a scan request PDU. /// /// Note that scanning is not yet implemented. /// /// # Parameters /// /// * `scanner`: Device address of the device in scanning state (sender of /// the request). /// * `adv`: Device address of the advertising device that this scan request /// is directed towards. pub fn scan_request(_scanner: DeviceAddress, _adv: DeviceAddress) -> Result<Self, Error> { unimplemented!() } /// Creates a scan response PDU. /// /// Note that scanning is not yet implemented. pub fn scan_response( advertiser_addr: DeviceAddress, scan_data: &[AdStructure], ) -> Result<Self, Error> { let mut payload = [0; MAX_PAYLOAD_SIZE]; let mut buf = ByteWriter::new(&mut payload[..]); buf.write_slice(advertiser_addr.raw()).unwrap(); for ad in scan_data { ad.to_bytes(&mut buf)?; } let left = buf.space_left(); let used = payload.len() - left; let mut header = Header::new(PduType::ScanRsp); header.set_payload_length(used as u8); header.set_tx_add(advertiser_addr.is_random()); header.set_rx_add(false); Ok(Self { header, payload_buf: payload, }) } pub fn header(&self) -> Header { self.header } pub fn payload(&self) -> &[u8] { let len = self.header.payload_length() as usize; &self.payload_buf[..len] } } impl fmt::Debug for PduBuf { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "({:?}, {:?})", self.header(), HexSlice(self.payload())) } } /// 16-bit Advertising Channel PDU header preceding the Payload. /// /// The header looks like this: /// /// ```notrust /// LSB MSB /// +------------+------------+---------+---------+--------------+------------+ /// | PDU Type | - | TxAdd | RxAdd | Length | - | /// | (4 bits) | (2 bits) | (1 bit) | (1 bit) | (6 bits) | (2 bits) | /// +------------+------------+---------+---------+--------------+------------+ /// ``` /// /// The `TxAdd` and `RxAdd` field are only used for some payloads, for all others, they should be /// set to 0. /// /// Length may be in range 6 to 37 (inclusive). With the 2-Byte header this is exactly the max. /// on-air packet size. #[derive(Copy, Clone)] pub struct Header(u16); const TXADD_MASK: u16 = 0b00000000_01000000; const RXADD_MASK: u16 = 0b00000000_10000000; impl Header { /// Creates a new Advertising Channel PDU header specifying the Payload type `ty`. pub fn new(ty: PduType) -> Self { Header(u16::from(u8::from(ty))) } pub fn parse(raw: &[u8]) -> Self { Header(LittleEndian::read_u16(&raw)) } /// Returns the raw representation of the header. /// /// The returned `u16` must be transmitted LSb first as the first 2 octets of the PDU. pub fn to_u16(&self) -> u16 { self.0 } /// Sets all bits in the header that are set in `mask`. fn set_header_bits(&mut self, mask: u16) { self.0 |= mask; } /// Clears all bits in the header that are set in `mask`. fn clear_header_bits(&mut self, mask: u16) { self.0 &= !mask; } /// Returns the PDU type specified in the header. pub fn type_(&self) -> PduType { PduType::from((self.0 & 0b00000000_00001111) as u8) } /// Returns the state of the `TxAdd` field. pub fn tx_add(&self) -> bool { self.0 & TXADD_MASK != 0 } /// Sets the `TxAdd` field's value. pub fn set_tx_add(&mut self, value: bool) { if value { self.set_header_bits(TXADD_MASK); } else { self.clear_header_bits(TXADD_MASK); } } /// Returns the state of the `RxAdd` field. pub fn rx_add(&self) -> bool { self.0 & RXADD_MASK != 0 } /// Sets the `RxAdd` field's value. pub fn set_rx_add(&mut self, value: bool) { if value { self.set_header_bits(RXADD_MASK); } else { self.clear_header_bits(RXADD_MASK); } } /// Returns the length of the payload in octets as specified in the `Length` field. /// /// According to the spec, the length must be in range 6...37, but this isn't checked by this /// function. pub fn payload_length(&self) -> u8 { ((self.0 & 0b00111111_00000000) >> 8) as u8 } /// Sets the payload length of this PDU. /// /// The `length` must be in range 6...37, otherwise this function panics. pub fn set_payload_length(&mut self, length: u8) { assert!(6 <= length && length <= 37); let header = self.0 & !0b00111111_00000000; self.0 = header | ((length as u16) << 8); } } impl fmt::Debug for Header { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { f.debug_struct("Header") .field("PDU Type", &self.type_()) .field("TxAdd", &self.tx_add()) .field("RxAdd", &self.rx_add()) .field("len", &self.payload_length()) .finish() } } impl<'a> FromBytes<'a> for Header { fn from_bytes(bytes: &mut ByteReader<'a>) -> Result<Self, Error> { let raw = bytes.read_u16_le()?; Ok(Header(raw)) } } impl ToBytes for Header { fn to_bytes(&self, writer: &mut ByteWriter) -> Result<(), Error> { writer.write_u16_le(self.0) } } enum_with_unknown! { /// 4-bit PDU type in [`Header`]. /// /// For more details, see [`PduBuf`]. /// /// [`Header`]: struct.Header.html /// [`PduBuf`]: struct.PduBuf.html #[derive(Debug, PartialEq, Eq)] pub enum PduType(u8) { /// Connectable undirected advertising event (`ADV_IND`). AdvInd = 0b0000, /// Connectable directed advertising event (`ADV_DIRECT_IND`). AdvDirectInd = 0b0001, /// Non-connectable undirected advertising event (`ADV_NONCONN_IND`). AdvNonconnInd = 0b0010, /// Scannable undirected advertising event (`ADV_SCAN_IND`). AdvScanInd = 0b0110, /// Scan request (`SCAN_REQ`). /// /// Sent by device in Scanning State, received by device in Advertising /// State. ScanReq = 0b0011, /// Scan response (`SCAN_RSP`). /// /// Sent by device in Advertising State, received by devicein Scanning /// State. ScanRsp = 0b0100, /// Connect request (`CONNECT_REQ`). /// /// Sent by device in Initiating State, received by device in /// Advertising State. ConnectReq = 0b0101, } } impl PduType { /// Returns whether this PDU type is a beacon advertisement. pub fn is_beacon(&self) -> bool { *self == PduType::AdvNonconnInd } /// Whether AD structures can follow the fixed data in a PDU of this type. pub fn allows_adv_data(&self) -> bool { match self { PduType::AdvInd | PduType::AdvNonconnInd | PduType::AdvScanInd | PduType::ScanRsp => { true } PduType::AdvDirectInd | PduType::ScanReq | PduType::ConnectReq | PduType::Unknown(_) => false, } } }