Adding new TCP socket APIs

Author: ryan-summers

CHANGELOG.md

@@ -11,6 +11,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Bump dependency version of `no-std-net` to `v0.6`.
 - Bump MSRV to 1.53.0 due to `no-std-net`'s use of or-patterns.
 - Added support for `core::net` with the `ip_in_core` feature.
+- [breaking] New APIs added to `TcpClientStack` to support more robust understanding of the TCP
+socket state
+    * New APIs include `is_open()`, `may_send()`, and `may_recv()`
 
 ## [0.6.0] - 2021-05-25
 

src/stack/tcp.rs

@@ -27,8 +27,21 @@ pub trait TcpClientStack {
 		remote: SocketAddr,
 	) -> nb::Result<(), Self::Error>;
 
-	/// Check if this socket is connected
-	fn is_connected(&mut self, socket: &Self::TcpSocket) -> Result<bool, Self::Error>;
+	/// Determine if a socket is opened.
+    ///
+    /// Returns `Ok(true)` if the TCP socket is actively ingressing and egressing packets. This
+    /// corresponds to any TCP state that is not `CLOSED` or `TIME-WAIT`.
+	fn is_open(&mut self, socket: &Self::TcpSocket) -> Result<bool, Self::Error>;
+
+    /// Check if the TCP socket can transmit data.
+    ///
+    /// Returns `Ok(true)` if the TCP transmit half is open and connected.
+    fn may_send(&mut self, socket: &Self::TcpSocket) -> Result<bool, Self::Error>;
+
+    /// Check if the TCP socket can receive data.
+    ///
+    /// Returns `Ok(true)` if the TCP receive half is open and connected.
+    fn may_receive(&mut self, socket: &Self::TcpSocket) -> Result<bool, Self::Error>;
 
 	/// Write to the stream.
 	///