Re-structure sat-rs

- Add new shared subcrate satrs-shared to split off some shared
  components not expected to change very often.
- Renmame `satrs-core` to `satrs`. It is expected that sat-rs will remain
  the primary crate, so the core information is superfluous, and core also
  implies stability, which will not be the case for some time.

satrs/src/hal/std/tcp_server.rs

@@ -0,0 +1,359 @@
+//! Generic TCP TMTC servers with different TMTC format flavours.
+use alloc::vec;
+use alloc::vec::Vec;
+use core::time::Duration;
+use socket2::{Domain, Socket, Type};
+use std::io::Read;
+use std::net::TcpListener;
+use std::net::{SocketAddr, TcpStream};
+use std::thread;
+
+use crate::tmtc::{ReceivesTc, TmPacketSource};
+use thiserror::Error;
+
+// Re-export the TMTC in COBS server.
+pub use crate::hal::std::tcp_cobs_server::{CobsTcParser, CobsTmSender, TcpTmtcInCobsServer};
+pub use crate::hal::std::tcp_spacepackets_server::{
+    SpacepacketsTcParser, SpacepacketsTmSender, TcpSpacepacketsServer,
+};
+
+/// Configuration struct for the generic TCP TMTC server
+///
+/// ## Parameters
+///
+/// * `addr` - Address of the TCP server.
+/// * `inner_loop_delay` - If a client connects for a longer period, but no TC is received or
+///     no TM needs to be sent, the TCP server will delay for the specified amount of time
+///     to reduce CPU load.
+/// * `tm_buffer_size` - Size of the TM buffer used to read TM from the [TmPacketSource] and
+///     encoding of that data. This buffer should at large enough to hold the maximum expected
+///     TM size read from the packet source.
+/// * `tc_buffer_size` - Size of the TC buffer used to read encoded telecommands sent from
+///     the client. It is recommended to make this buffer larger to allow reading multiple
+///     consecutive packets as well, for example by using common buffer sizes like 4096 or 8192
+///     byte. The buffer should at the very least be large enough to hold the maximum expected
+///     telecommand size.
+/// * `reuse_addr` - Can be used to set the `SO_REUSEADDR` option on the raw socket. This is
+///     especially useful if the address and port are static for the server. Set to false by
+///     default.
+/// * `reuse_port` - Can be used to set the `SO_REUSEPORT` option on the raw socket. This is
+///     especially useful if the address and port are static for the server. Set to false by
+///     default.
+#[derive(Debug, Copy, Clone)]
+pub struct ServerConfig {
+    pub addr: SocketAddr,
+    pub inner_loop_delay: Duration,
+    pub tm_buffer_size: usize,
+    pub tc_buffer_size: usize,
+    pub reuse_addr: bool,
+    pub reuse_port: bool,
+}
+
+impl ServerConfig {
+    pub fn new(
+        addr: SocketAddr,
+        inner_loop_delay: Duration,
+        tm_buffer_size: usize,
+        tc_buffer_size: usize,
+    ) -> Self {
+        Self {
+            addr,
+            inner_loop_delay,
+            tm_buffer_size,
+            tc_buffer_size,
+            reuse_addr: false,
+            reuse_port: false,
+        }
+    }
+}
+
+#[derive(Error, Debug)]
+pub enum TcpTmtcError<TmError, TcError> {
+    #[error("TM retrieval error: {0}")]
+    TmError(TmError),
+    #[error("TC retrieval error: {0}")]
+    TcError(TcError),
+    #[error("io error: {0}")]
+    Io(#[from] std::io::Error),
+}
+
+/// Result of one connection attempt. Contains the client address if a connection was established,
+/// in addition to the number of telecommands and telemetry packets exchanged.
+#[derive(Debug, Default)]
+pub struct ConnectionResult {
+    pub addr: Option<SocketAddr>,
+    pub num_received_tcs: u32,
+    pub num_sent_tms: u32,
+}
+
+/// Generic parser abstraction for an object which can parse for telecommands given a raw
+/// bytestream received from a TCP socket and send them to a generic [ReceivesTc] telecommand
+/// receiver. This allows different encoding schemes for telecommands.
+pub trait TcpTcParser<TmError, TcError> {
+    fn handle_tc_parsing(
+        &mut self,
+        tc_buffer: &mut [u8],
+        tc_receiver: &mut (impl ReceivesTc<Error = TcError> + ?Sized),
+        conn_result: &mut ConnectionResult,
+        current_write_idx: usize,
+        next_write_idx: &mut usize,
+    ) -> Result<(), TcpTmtcError<TmError, TcError>>;
+}
+
+/// Generic sender abstraction for an object which can pull telemetry from a given TM source
+/// using a [TmPacketSource] and then send them back to a client using a given [TcpStream].
+/// The concrete implementation can also perform any encoding steps which are necessary before
+/// sending back the data to a client.
+pub trait TcpTmSender<TmError, TcError> {
+    fn handle_tm_sending(
+        &mut self,
+        tm_buffer: &mut [u8],
+        tm_source: &mut (impl TmPacketSource<Error = TmError> + ?Sized),
+        conn_result: &mut ConnectionResult,
+        stream: &mut TcpStream,
+    ) -> Result<bool, TcpTmtcError<TmError, TcError>>;
+}
+
+/// TCP TMTC server implementation for exchange of generic TMTC packets in a generic way which
+/// stays agnostic to the encoding scheme and format used for both telecommands and telemetry.
+///
+/// This server implements a generic TMTC handling logic and allows modifying its behaviour
+/// through the following 4 core abstractions:
+///
+/// 1. [TcpTcParser] to parse for telecommands from the raw bytestream received from a client.
+/// 2. Parsed telecommands will be sent to the [ReceivesTc] telecommand receiver.
+/// 3. [TcpTmSender] to send telemetry pulled from a TM source back to the client.
+/// 4. [TmPacketSource] as a generic TM source used by the [TcpTmSender].
+///
+/// It is possible to specify custom abstractions to build a dedicated TCP TMTC server without
+/// having to re-implement common logic.
+///
+/// Currently, this framework offers the following concrete implementations:
+///
+/// 1. [TcpTmtcInCobsServer] to exchange TMTC wrapped inside the COBS framing protocol.
+pub struct TcpTmtcGenericServer<
+    TmError,
+    TcError,
+    TmSource: TmPacketSource<Error = TmError>,
+    TcReceiver: ReceivesTc<Error = TcError>,
+    TmSender: TcpTmSender<TmError, TcError>,
+    TcParser: TcpTcParser<TmError, TcError>,
+> {
+    pub(crate) listener: TcpListener,
+    pub(crate) inner_loop_delay: Duration,
+    pub(crate) tm_source: TmSource,
+    pub(crate) tm_buffer: Vec<u8>,
+    pub(crate) tc_receiver: TcReceiver,
+    pub(crate) tc_buffer: Vec<u8>,
+    tc_handler: TcParser,
+    tm_handler: TmSender,
+}
+
+impl<
+        TmError: 'static,
+        TcError: 'static,
+        TmSource: TmPacketSource<Error = TmError>,
+        TcReceiver: ReceivesTc<Error = TcError>,
+        TmSender: TcpTmSender<TmError, TcError>,
+        TcParser: TcpTcParser<TmError, TcError>,
+    > TcpTmtcGenericServer<TmError, TcError, TmSource, TcReceiver, TmSender, TcParser>
+{
+    /// Create a new generic TMTC server instance.
+    ///
+    /// ## Parameter
+    ///
+    /// * `cfg` - Configuration of the server.
+    /// * `tc_parser` - Parser which extracts telecommands from the raw bytestream received from
+    ///    the client.
+    /// * `tm_sender` - Sends back telemetry to the client using the specified TM source.
+    /// * `tm_source` - Generic TM source used by the server to pull telemetry packets which are
+    ///     then sent back to the client.
+    /// * `tc_receiver` - Any received telecommand which was decoded successfully will be forwarded
+    ///     to this TC receiver.
+    pub fn new(
+        cfg: ServerConfig,
+        tc_parser: TcParser,
+        tm_sender: TmSender,
+        tm_source: TmSource,
+        tc_receiver: TcReceiver,
+    ) -> Result<Self, std::io::Error> {
+        // Create a TCP listener bound to two addresses.
+        let socket = Socket::new(Domain::IPV4, Type::STREAM, None)?;
+        socket.set_reuse_address(cfg.reuse_addr)?;
+        #[cfg(unix)]
+        socket.set_reuse_port(cfg.reuse_port)?;
+        let addr = (cfg.addr).into();
+        socket.bind(&addr)?;
+        socket.listen(128)?;
+        Ok(Self {
+            tc_handler: tc_parser,
+            tm_handler: tm_sender,
+            listener: socket.into(),
+            inner_loop_delay: cfg.inner_loop_delay,
+            tm_source,
+            tm_buffer: vec![0; cfg.tm_buffer_size],
+            tc_receiver,
+            tc_buffer: vec![0; cfg.tc_buffer_size],
+        })
+    }
+
+    /// Retrieve the internal [TcpListener] class.
+    pub fn listener(&mut self) -> &mut TcpListener {
+        &mut self.listener
+    }
+
+    /// Can be used to retrieve the local assigned address of the TCP server. This is especially
+    /// useful if using the port number 0 for OS auto-assignment.
+    pub fn local_addr(&self) -> std::io::Result<SocketAddr> {
+        self.listener.local_addr()
+    }
+
+    /// This call is used to handle the next connection to a client. Right now, it performs
+    /// the following steps:
+    ///
+    /// 1. It calls the [std::net::TcpListener::accept] method internally using the blocking API
+    ///    until a client connects.
+    /// 2. It reads all the telecommands from the client and parses all received data using the
+    ///    user specified [TcpTcParser].
+    /// 3. After reading and parsing all telecommands, it sends back all telemetry using the
+    ///    user specified [TcpTmSender].
+    ///
+    /// The server will delay for a user-specified period if the client connects to the server
+    /// for prolonged periods and there is no traffic for the server. This is the case if the
+    /// client does not send any telecommands and no telemetry needs to be sent back to the client.
+    pub fn handle_next_connection(
+        &mut self,
+    ) -> Result<ConnectionResult, TcpTmtcError<TmError, TcError>> {
+        let mut connection_result = ConnectionResult::default();
+        let mut current_write_idx;
+        let mut next_write_idx = 0;
+        let (mut stream, addr) = self.listener.accept()?;
+        stream.set_nonblocking(true)?;
+        connection_result.addr = Some(addr);
+        current_write_idx = next_write_idx;
+        loop {
+            let read_result = stream.read(&mut self.tc_buffer[current_write_idx..]);
+            match read_result {
+                Ok(0) => {
+                    // Connection closed by client. If any TC was read, parse for complete packets.
+                    // After that, break the outer loop.
+                    if current_write_idx > 0 {
+                        self.tc_handler.handle_tc_parsing(
+                            &mut self.tc_buffer,
+                            &mut self.tc_receiver,
+                            &mut connection_result,
+                            current_write_idx,
+                            &mut next_write_idx,
+                        )?;
+                    }
+                    break;
+                }
+                Ok(read_len) => {
+                    current_write_idx += read_len;
+                    // TC buffer is full, we must parse for complete packets now.
+                    if current_write_idx == self.tc_buffer.capacity() {
+                        self.tc_handler.handle_tc_parsing(
+                            &mut self.tc_buffer,
+                            &mut self.tc_receiver,
+                            &mut connection_result,
+                            current_write_idx,
+                            &mut next_write_idx,
+                        )?;
+                        current_write_idx = next_write_idx;
+                    }
+                }
+                Err(e) => match e.kind() {
+                    // As per [TcpStream::set_read_timeout] documentation, this should work for
+                    // both UNIX and Windows.
+                    std::io::ErrorKind::WouldBlock | std::io::ErrorKind::TimedOut => {
+                        self.tc_handler.handle_tc_parsing(
+                            &mut self.tc_buffer,
+                            &mut self.tc_receiver,
+                            &mut connection_result,
+                            current_write_idx,
+                            &mut next_write_idx,
+                        )?;
+                        current_write_idx = next_write_idx;
+
+                        if !self.tm_handler.handle_tm_sending(
+                            &mut self.tm_buffer,
+                            &mut self.tm_source,
+                            &mut connection_result,
+                            &mut stream,
+                        )? {
+                            // No TC read, no TM was sent, but the client has not disconnected.
+                            // Perform an inner delay to avoid burning CPU time.
+                            thread::sleep(self.inner_loop_delay);
+                        }
+                    }
+                    _ => {
+                        return Err(TcpTmtcError::Io(e));
+                    }
+                },
+            }
+        }
+        self.tm_handler.handle_tm_sending(
+            &mut self.tm_buffer,
+            &mut self.tm_source,
+            &mut connection_result,
+            &mut stream,
+        )?;
+        Ok(connection_result)
+    }
+}
+
+#[cfg(test)]
+pub(crate) mod tests {
+    use std::sync::Mutex;
+
+    use alloc::{collections::VecDeque, sync::Arc, vec::Vec};
+
+    use crate::tmtc::{ReceivesTcCore, TmPacketSourceCore};
+
+    #[derive(Default, Clone)]
+    pub(crate) struct SyncTcCacher {
+        pub(crate) tc_queue: Arc<Mutex<VecDeque<Vec<u8>>>>,
+    }
+    impl ReceivesTcCore for SyncTcCacher {
+        type Error = ();
+
+        fn pass_tc(&mut self, tc_raw: &[u8]) -> Result<(), Self::Error> {
+            let mut tc_queue = self.tc_queue.lock().expect("tc forwarder failed");
+            tc_queue.push_back(tc_raw.to_vec());
+            Ok(())
+        }
+    }
+
+    #[derive(Default, Clone)]
+    pub(crate) struct SyncTmSource {
+        tm_queue: Arc<Mutex<VecDeque<Vec<u8>>>>,
+    }
+
+    impl SyncTmSource {
+        pub(crate) fn add_tm(&mut self, tm: &[u8]) {
+            let mut tm_queue = self.tm_queue.lock().expect("locking tm queue failec");
+            tm_queue.push_back(tm.to_vec());
+        }
+    }
+
+    impl TmPacketSourceCore for SyncTmSource {
+        type Error = ();
+
+        fn retrieve_packet(&mut self, buffer: &mut [u8]) -> Result<usize, Self::Error> {
+            let mut tm_queue = self.tm_queue.lock().expect("locking tm queue failed");
+            if !tm_queue.is_empty() {
+                let next_vec = tm_queue.front().unwrap();
+                if buffer.len() < next_vec.len() {
+                    panic!(
+                        "provided buffer too small, must be at least {} bytes",
+                        next_vec.len()
+                    );
+                }
+                let next_vec = tm_queue.pop_front().unwrap();
+                buffer[0..next_vec.len()].copy_from_slice(&next_vec);
+                return Ok(next_vec.len());
+            }
+            Ok(0)
+        }
+    }
+}