floss: Add Rust access to kernel BT socket am: ae0dcf07c7 (2f250122) · Commits · e / os / android_packages_modules_Bluetooth

system/gd/rust/linux/socket/Cargo.toml

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		#
		# Copyright 2022 Google, Inc.
		#
		# Licensed under the Apache License, Version 2.0 (the "License");
		# you may not use this file except in compliance with the License.
		# You may obtain a copy of the License at:
		#
		# http://www.apache.org/licenses/LICENSE-2.0
		#
		# Unless required by applicable law or agreed to in writing, software
		# distributed under the License is distributed on an "AS IS" BASIS,
		# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		# See the License for the specific language governing permissions and
		# limitations under the License.
		[package]
		name = "bt_socket"
		version = "0.0.1"
		edition = "2021"

		[dependencies]
		libc = "0.2"
		log = "0.4.14"
		num-derive = "0.3"
		num-traits = "0.2"

		[lib]
		crate-type = ["rlib"]

system/gd/rust/linux/socket/src/lib.rs

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		//! This library provides access to the Bluetooth socket. Included are ways to bind to specific
		//! channels (i.e. control / user) and send/receive + encode/decode MGMT commands and events.

		use std::mem;
		use std::os::unix::io::{AsRawFd, RawFd};

		#[macro_use]
		extern crate num_derive;

		use libc;
		use log::debug;
		use num_traits::cast::{FromPrimitive, ToPrimitive};

		/// Socket protocol constant for HCI.
		const BTPROTO_HCI: u8 = 1;

		/// Non-existent HCI device for binding BT sockets.
		pub const HCI_DEV_NONE: u16 = 0xFFFF;

		/// Bindable configurations for open HCI sockets.
		#[derive(ToPrimitive)]
		#[repr(u16)]
		pub enum HciChannels {
		Raw = 0,
		User = 1,
		Monitor = 2,
		Control = 3,
		Logging = 4,

		Unbound = 0xFFFF,
		}

		impl From<HciChannels> for u16 {
		fn from(item: HciChannels) -> Self {
		item.to_u16().unwrap()
		}
		}

		#[repr(C)]
		struct SockAddrHci {
		hci_family: libc::sa_family_t,
		hci_dev: u16,
		hci_channel: u16,
		}

		/// Maximum size of a MGMT command or event packet.
		const MGMT_PKT_DATA_MAX: usize = 1024;

		/// Size of MGMT packet header.
		const MGMT_PKT_HEADER_SIZE: usize = 6;

		/// Total size of MGMT packet.
		pub const MGMT_PKT_SIZE_MAX: usize = MGMT_PKT_HEADER_SIZE + MGMT_PKT_DATA_MAX;

		/// Represents a MGMT packet (either command or event) in the raw form that can
		/// be read from or written to the MGMT socket.
		#[derive(Debug)]
		pub struct MgmtPacket {
		opcode: u16,
		index: u16,
		len: u16,
		data: Vec<u8>,
		}

		impl MgmtPacket {
		fn write_to_wire(&self) -> Vec<u8> {
		let mut v: Vec<u8> = Vec::new();

		v.extend_from_slice(self.opcode.to_le_bytes().as_slice());
		v.extend_from_slice(self.index.to_le_bytes().as_slice());
		v.extend_from_slice(self.len.to_le_bytes().as_slice());
		v.extend_from_slice(self.data.as_slice());

		v
		}
		}

		#[derive(FromPrimitive, ToPrimitive)]
		pub enum MgmtCommandOpcode {
		ReadIndexList = 0x3,
		}

		impl From<MgmtCommandOpcode> for u16 {
		fn from(item: MgmtCommandOpcode) -> Self {
		item.to_u16().unwrap()
		}
		}

		impl TryFrom<u16> for MgmtCommandOpcode {
		type Error = ();

		fn try_from(item: u16) -> Result<Self, Self::Error> {
		match MgmtCommandOpcode::from_u16(item) {
		Some(v) => Ok(v),
		None => Err(()),
		}
		}
		}

		pub enum MgmtCommand {
		ReadIndexList,
		}

		impl From<MgmtCommand> for MgmtPacket {
		fn from(item: MgmtCommand) -> Self {
		match item {
		MgmtCommand::ReadIndexList => MgmtPacket {
		opcode: MgmtCommandOpcode::ReadIndexList.into(),
		index: HCI_DEV_NONE,
		len: 0,
		data: Vec::new(),
		},
		}
		}
		}

		#[derive(FromPrimitive, ToPrimitive, Debug)]
		pub enum MgmtEventOpcode {
		CommandComplete = 0x1,
		IndexAdded = 0x4,
		IndexRemoved = 0x5,
		}

		impl TryFrom<u16> for MgmtEventOpcode {
		type Error = ();

		fn try_from(item: u16) -> Result<Self, Self::Error> {
		match MgmtEventOpcode::from_u16(item) {
		Some(v) => Ok(v),
		None => Err(()),
		}
		}
		}

		#[derive(Debug)]
		pub enum MgmtCommandResponse {
		// This is a meta enum that is only used to indicate that the remaining data
		// for this response has been dropped.
		DataUnused,

		ReadIndexList { num_intf: u16, interfaces: Vec<u16> },
		}

		#[derive(Debug)]
		pub enum MgmtEvent {
		/// Command completion event.
		CommandComplete { opcode: u16, status: u8, response: MgmtCommandResponse },

		/// HCI device was added.
		IndexAdded(u16),

		/// HCI device was removed.
		IndexRemoved(u16),
		}

		impl TryFrom<MgmtPacket> for MgmtEvent {
		type Error = ();

		fn try_from(item: MgmtPacket) -> Result<Self, Self::Error> {
		MgmtEventOpcode::try_from(item.opcode).and_then(\|ev\| {
		Ok(match ev {
		MgmtEventOpcode::CommandComplete => {
		// Minimum 3 bytes required for opcode + status
		if item.data.len() < 3 {
		debug!("CommandComplete packet too small: {}", item.data.len());
		return Err(());
		}

		let (opcode_arr, rest) = item.data.split_at(std::mem::size_of::<u16>());

		let opcode = u16::from_le_bytes(opcode_arr.try_into().unwrap());
		let status = rest[0];
		let (_, rest) = rest.split_at(std::mem::size_of::<u8>());

		let response = if let Ok(op) = MgmtCommandOpcode::try_from(opcode) {
		match op {
		MgmtCommandOpcode::ReadIndexList => {
		if rest.len() < 2 {
		debug!("ReadIndexList packet too small: {}", rest.len());
		return Err(());
		}

		let (len_arr, rest) = rest.split_at(std::mem::size_of::<u16>());
		let len = u16::from_le_bytes(len_arr.try_into().unwrap());

		let explen = (len as usize) * 2usize;
		if rest.len() < explen {
		debug!(
		"ReadIndexList len malformed: expect = {}, actual = {}",
		explen,
		rest.len()
		);
		return Err(());
		}

		let interfaces: Vec<u16> = rest
		.iter()
		.step_by(2)
		.zip(rest.iter().skip(1).step_by(2))
		.map(\|bytes\| u16::from_le_bytes([bytes.0, bytes.1]))
		.collect();

		MgmtCommandResponse::ReadIndexList { num_intf: len, interfaces }
		}
		}
		} else {
		MgmtCommandResponse::DataUnused
		};

		MgmtEvent::CommandComplete { opcode, status, response }
		}
		MgmtEventOpcode::IndexAdded => MgmtEvent::IndexAdded(item.index),
		MgmtEventOpcode::IndexRemoved => MgmtEvent::IndexRemoved(item.index),
		})
		})
		}
		}

		/// This struct is used to keep track of an open Bluetooth MGMT socket and it's
		/// current state. It is meant to be used in two ways: call MGMT commands that
		/// don't have a open hci device requirement or support being called when the
		/// device is userchannel owned.
		#[repr(C)]
		pub struct BtSocket {
		sock_fd: i32,
		channel_type: HciChannels,
		}

		// Close given file descriptor.
		fn close_fd(fd: i32) -> i32 {
		unsafe { libc::close(fd) }
		}

		impl Drop for BtSocket {
		fn drop(&mut self) {
		if self.has_valid_fd() {
		close_fd(self.sock_fd);
		}
		}
		}

		impl BtSocket {
		pub fn new() -> Self {
		BtSocket { sock_fd: -1, channel_type: HciChannels::Unbound }
		}

		/// Is the current file descriptor valid?
		pub fn has_valid_fd(&self) -> bool {
		self.sock_fd >= 0
		}

		/// Open raw socket to Bluetooth. This should be the first thing called.
		pub fn open(&mut self) -> i32 {
		if self.has_valid_fd() {
		return self.sock_fd;
		}

		unsafe {
		let sockfd = libc::socket(
		libc::PF_BLUETOOTH,
		libc::SOCK_RAW \| libc::SOCK_NONBLOCK,
		BTPROTO_HCI.into(),
		);

		if sockfd >= 0 {
		self.sock_fd = sockfd;
		}

		sockfd
		}
		}

		/// Bind socket to a specific HCI channel type.
		pub fn bind_channel(&mut self, channel: HciChannels, hci_dev: u16) -> i32 {
		unsafe {
		let addr = SockAddrHci {
		// AF_BLUETOOTH can always be cast into u16
		hci_family: libc::sa_family_t::try_from(libc::AF_BLUETOOTH).unwrap(),
		hci_dev,
		hci_channel: channel.into(),
		};

		return libc::bind(
		self.sock_fd,
		(&addr as const SockAddrHci) as const libc::sockaddr,
		mem::size_of::<SockAddrHci>() as u32,
		);
		}
		}

		/// Take ownership of the file descriptor owned by this context. The caller
		/// is responsible for closing the underlying socket if it is open (this is
		/// intended to be used with something like AsyncFd).
		pub fn take_fd(&mut self) -> i32 {
		let fd = self.sock_fd;
		self.sock_fd = -1;

		fd
		}

		pub fn read_mgmt_packet(&mut self) -> Option<MgmtPacket> {
		if !self.has_valid_fd() {
		return None;
		}

		unsafe {
		let mut buf: [u8; MGMT_PKT_SIZE_MAX] = [0; MGMT_PKT_SIZE_MAX];
		let mut bytes_read;
		loop {
		bytes_read = libc::read(
		self.sock_fd,
		buf.as_mut_ptr() as *mut libc::c_void,
		MGMT_PKT_SIZE_MAX,
		);

		// Retry if -EINTR
		let retry = (bytes_read == -1)
		&& std::io::Error::last_os_error().raw_os_error().unwrap_or(0) == libc::EINTR;

		if !retry {
		break;
		}
		}

		// Exit early on error.
		if bytes_read == -1 {
		debug!(
		"read_mgmt_packet failed with errno {}",
		std::io::Error::last_os_error().raw_os_error().unwrap_or(0)
		);
		return None;
		}

		if bytes_read < (MGMT_PKT_HEADER_SIZE as isize) {
		debug!("read_mgmt_packet got {} bytes (not enough for header)", bytes_read);
		return None;
		}

		let data_size: usize =
		(bytes_read - (MGMT_PKT_HEADER_SIZE as isize)).try_into().unwrap();

		let (opcode_arr, rest) = buf.split_at(std::mem::size_of::<u16>());
		let (index_arr, rest) = rest.split_at(std::mem::size_of::<u16>());
		let (len_arr, rest) = rest.split_at(std::mem::size_of::<u16>());
		let data_arr = rest;

		Some(MgmtPacket {
		opcode: u16::from_le_bytes(opcode_arr.try_into().unwrap()),
		index: u16::from_le_bytes(index_arr.try_into().unwrap()),
		len: u16::from_le_bytes(len_arr.try_into().unwrap()),
		data: match data_size {
		x if x > 0 => data_arr[..x].iter().map(\|x\| *x).collect::<Vec<u8>>(),
		_ => Vec::new(),
		},
		})
		}
		}

		pub fn write_mgmt_packet(&mut self, packet: MgmtPacket) -> isize {
		let wire_data = packet.write_to_wire();
		unsafe {
		let mut bytes_written;
		loop {
		bytes_written = libc::write(
		self.sock_fd,
		wire_data.as_slice().as_ptr() as *const libc::c_void,
		wire_data.len(),
		);

		// Retry if -EINTR
		let retry = bytes_written == -1
		&& std::io::Error::last_os_error().raw_os_error().unwrap_or(0) == libc::EINTR;

		if !retry {
		break;
		}
		}

		bytes_written
		}
		}
		}

		impl AsRawFd for BtSocket {
		fn as_raw_fd(&self) -> RawFd {
		self.sock_fd
		}
		}

		#[cfg(test)]
		mod tests {
		use super::*;

		#[test]
		fn mgmt_tryfrom_indexlist() {
		let mut packet = MgmtPacket {
		opcode: MgmtEventOpcode::CommandComplete.to_u16().unwrap(),
		index: 0,
		len: 0,
		// CommandComplete consists of opcode (u16), status (u8) and the response.
		// ReadIndexList consists of u16 (num intf) and Vec<u16> (interfaces).
		// Return a few values to test the parser.
		data: vec![
		/opcode/ 0x03, 0x00, /status/ 0x0, /num_intf/ 0x03, 0x00,
		/interfaces/ 0x00, 0x00, 0x05, 0x00, 0xef, 0xbe,
		],
		};
		packet.len = packet.data.len().try_into().unwrap_or(0);

		let event = packet.try_into();
		assert_eq!(true, event.is_ok(), "Packet doesn't parse into event.");
		if let Ok(ev) = event {
		if let MgmtEvent::CommandComplete { opcode, status, response } = ev {
		assert_eq!(opcode, 0x3);
		assert_eq!(status, 0x0);
		if let MgmtCommandResponse::ReadIndexList { num_intf, interfaces } = response {
		assert_eq!(3, num_intf);
		assert_eq!(vec![0x0, 0x5, 0xbeef], interfaces);
		} else {
		panic!("Command Response is not ReadIndexList");
		}
		} else {
		panic!("Event is not Command Complete");
		}
		}
		}
		}