1 files changed, 73 insertions, 0 deletions
diff --git a/src/net/packet.rs b/src/net/packet.rs
new file mode 100644
index 0000000..2d97504
--- /dev/null
+++ b/src/net/packet.rs
@@ -0,0 +1,73 @@
+use serde::de::DeserializeOwned;
+use serde::{Deserialize, Serialize};
+use std::fmt::Debug;
+use std::io;
+use std::mem;
+
+#[derive(Debug, Deserialize, Serialize)]
+pub(super) enum Packet<P: 'static + Send + Debug> {
+    Cargo(P),
+    Disconnect,
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum PacketRwError {
+    #[error("packet could not be properly deserialised: {0}")]
+    DeserialiseError(bincode::Error),
+    #[error("packet could not be properly serialised: {0}")]
+    SerialiseError(bincode::Error),
+    #[error("unable to read packet from stream: {0}")]
+    IOError(io::Error),
+    #[error("connection was closed from the remote end")]
+    Closed,
+}
+
+impl<P: 'static + Send + Debug + DeserializeOwned + Serialize> Packet<P> {
+    pub fn write_to_stream(&self, stream: &mut impl io::Write) -> Result<(), PacketRwError> {
+        let data: Vec<u8> =
+            bincode::serialize(&self).map_err(|err| PacketRwError::SerialiseError(err))?;
+
+        // Write head with packet length
+        assert!(data.len() as u64 <= u32::MAX as u64);
+        let len = data.len() as u32;
+        let len = bincode::serialize(&len).map_err(|err| PacketRwError::SerialiseError(err))?;
+        stream
+            .write_all(&len)
+            .map_err(|err| PacketRwError::IOError(err))?;
+
+        // Write the data of the packet and pray all errors are caught.
+        Ok(stream
+            .write_all(&data)
+            .map_err(|err| PacketRwError::IOError(err))?)
+    }
+
+    pub fn read_from_stream(stream: &mut impl io::Read) -> Result<Self, PacketRwError> {
+        // Read packet head which informs us of the length.
+        let mut len = vec![0; mem::size_of::<u32>()];
+        stream.read_exact(&mut len).map_err(|err| {
+            if err.kind() == io::ErrorKind::UnexpectedEof {
+                PacketRwError::Closed
+            } else {
+                PacketRwError::IOError(err)
+            }
+        })?;
+        let len: u32 = bincode::deserialize(&len)
+            .expect("Unable to deserialise length of packet. Stream is corrupted.");
+
+        // Read all data from the packet according to the length.
+        let mut data = vec![0; len as usize];
+        match stream.read_exact(&mut data) {
+            Ok(()) => {
+                let res: Result<Self, bincode::Error> = bincode::deserialize(&data);
+                Ok(res.map_err(|err| PacketRwError::DeserialiseError(err))?)
+            }
+            Err(err) => {
+                if err.kind() == io::ErrorKind::UnexpectedEof {
+                    Err(PacketRwError::Closed)
+                } else {
+                    Err(PacketRwError::IOError(err))
+                }
+            }
+        }
+    }
+}