From 6b50d28ba1aca847b47e15c81713e32c2ff371da Mon Sep 17 00:00:00 2001
From: Ruihan Li <lrh2000@pku.edu.cn>
Date: Fri, 26 Jul 2024 22:47:42 +0800
Subject: [PATCH] Remove unnecessary self-connecting check

---
 kernel/aster-nix/src/net/socket/unix/addr.rs  | 12 +---------
 .../src/net/socket/unix/stream/init.rs        | 12 +++-------
 .../src/net/socket/unix/stream/socket.rs      | 13 +++++++++-
 test/apps/network/unix_err.c                  | 24 +++++++++++++++++++
 4 files changed, 40 insertions(+), 21 deletions(-)

diff --git a/kernel/aster-nix/src/net/socket/unix/addr.rs b/kernel/aster-nix/src/net/socket/unix/addr.rs
index 5c67c767f..778a62532 100644
--- a/kernel/aster-nix/src/net/socket/unix/addr.rs
+++ b/kernel/aster-nix/src/net/socket/unix/addr.rs
@@ -9,22 +9,12 @@ pub enum UnixSocketAddr {
     Abstract(Vec<u8>),
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub(super) enum UnixSocketAddrBound {
     Path(Arc<Dentry>),
     Abstract(Vec<u8>),
 }
 
-impl PartialEq for UnixSocketAddrBound {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Self::Abstract(l0), Self::Abstract(r0)) => l0 == r0,
-            (Self::Path(l0), Self::Path(r0)) => Arc::ptr_eq(l0.inode(), r0.inode()),
-            _ => false,
-        }
-    }
-}
-
 impl TryFrom<SocketAddr> for UnixSocketAddr {
     type Error = Error;
 
diff --git a/kernel/aster-nix/src/net/socket/unix/stream/init.rs b/kernel/aster-nix/src/net/socket/unix/stream/init.rs
index ac9d83c4a..68567f83e 100644
--- a/kernel/aster-nix/src/net/socket/unix/stream/init.rs
+++ b/kernel/aster-nix/src/net/socket/unix/stream/init.rs
@@ -45,17 +45,11 @@ impl Init {
     }
 
     pub(super) fn connect(&self, remote_addr: &UnixSocketAddrBound) -> Result<Connected> {
-        let addr = self.addr();
-
-        if let Some(addr) = addr {
-            if *addr == *remote_addr {
-                return_errno_with_message!(Errno::EINVAL, "try to connect to self is invalid");
-            }
-        }
-
-        let (this_end, remote_end) = Endpoint::new_pair(addr.cloned(), Some(remote_addr.clone()));
+        let (this_end, remote_end) =
+            Endpoint::new_pair(self.addr.clone(), Some(remote_addr.clone()));
 
         push_incoming(remote_addr, remote_end)?;
+
         Ok(Connected::new(this_end))
     }
 
diff --git a/kernel/aster-nix/src/net/socket/unix/stream/socket.rs b/kernel/aster-nix/src/net/socket/unix/stream/socket.rs
index 930933bf3..db69f4c19 100644
--- a/kernel/aster-nix/src/net/socket/unix/stream/socket.rs
+++ b/kernel/aster-nix/src/net/socket/unix/stream/socket.rs
@@ -222,9 +222,20 @@ impl Socket for UnixStreamSocket {
             }
         };
 
+        // Note that the Linux kernel implementation locks the remote socket and checks to see if
+        // it is listening first. This is different from our implementation, which locks the local
+        // socket and checks the state of the local socket first.
+        //
+        // The difference may result in different error codes, but it's doubtful that this will
+        // ever lead to real problems.
+        //
+        // See also <https://elixir.bootlin.com/linux/v6.10.4/source/net/unix/af_unix.c#L1527>.
+
         let connected = match &*self.state.read() {
             State::Init(init) => init.connect(&remote_addr)?,
-            State::Listen(_) => return_errno_with_message!(Errno::EINVAL, "the socket is listened"),
+            State::Listen(_) => {
+                return_errno_with_message!(Errno::EINVAL, "the socket is listening")
+            }
             State::Connected(_) => {
                 return_errno_with_message!(Errno::EISCONN, "the socket is connected")
             }
diff --git a/test/apps/network/unix_err.c b/test/apps/network/unix_err.c
index ac4872794..63c0efdcd 100644
--- a/test/apps/network/unix_err.c
+++ b/test/apps/network/unix_err.c
@@ -194,3 +194,27 @@ FN_TEST(getpeername)
 			 memcmp(&addr, &UNNAMED_ADDR, UNNAMED_ADDRLEN) == 0);
 }
 END_TEST()
+
+FN_TEST(connect)
+{
+	TEST_ERRNO(connect(sk_unbound, (struct sockaddr *)&BOUND_ADDR,
+			   BOUND_ADDRLEN),
+		   ECONNREFUSED);
+
+	TEST_ERRNO(connect(sk_bound, (struct sockaddr *)&BOUND_ADDR,
+			   BOUND_ADDRLEN),
+		   ECONNREFUSED);
+
+	TEST_ERRNO(connect(sk_listen, (struct sockaddr *)&LISTEN_ADDR,
+			   LISTEN_ADDRLEN),
+		   EINVAL);
+
+	TEST_ERRNO(connect(sk_connected, (struct sockaddr *)&LISTEN_ADDR,
+			   LISTEN_ADDRLEN),
+		   EISCONN);
+
+	TEST_ERRNO(connect(sk_connected, (struct sockaddr *)&LISTEN_ADDR,
+			   LISTEN_ADDRLEN),
+		   EISCONN);
+}
+END_TEST()