From 2d5555937d87f8c64e4d19a76ac6c8d0f4d7c77d Mon Sep 17 00:00:00 2001
From: Luke Bakken <luke@bakken.io>
Date: Wed, 8 Feb 2023 10:02:31 -0800
Subject: [PATCH 1/2] Set channels and allocator to nil in shutdown

Follow up to #171

cc @Zerpet
---
 connection.go | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/connection.go b/connection.go
index 23f1832..d8766ee 100644
--- a/connection.go
+++ b/connection.go
@@ -551,8 +551,8 @@ func (c *Connection) shutdown(err *Error) {
 
 		c.conn.Close()
 
-		c.channels = map[uint16]*Channel{}
-		c.allocator = newAllocator(1, c.Config.ChannelMax)
+		c.channels = nil
+		c.allocator = nil
 		c.noNotify = true
 	})
 }
@@ -766,8 +766,10 @@ func (c *Connection) releaseChannel(id uint16) {
 	c.m.Lock()
 	defer c.m.Unlock()
 
-	delete(c.channels, id)
-	c.allocator.release(int(id))
+	if !c.IsClosed() {
+		delete(c.channels, id)
+		c.allocator.release(int(id))
+	}
 }
 
 // openChannel allocates and opens a channel, must be paired with closeChannel
@@ -915,6 +917,7 @@ func (c *Connection) openTune(config Config, auth Authentication) error {
 	// Edge case that may race with c.shutdown()
 	// https://github.com/rabbitmq/amqp091-go/issues/170
 	c.m.Lock()
+
 	// When the server and client both use default 0, then the max channel is
 	// only limited by uint16.
 	c.Config.ChannelMax = pick(config.ChannelMax, int(tune.ChannelMax))
@@ -922,6 +925,9 @@ func (c *Connection) openTune(config Config, auth Authentication) error {
 		c.Config.ChannelMax = defaultChannelMax
 	}
 	c.Config.ChannelMax = min(c.Config.ChannelMax, maxChannelMax)
+
+	c.allocator = newAllocator(1, c.Config.ChannelMax)
+
 	c.m.Unlock()
 
 	// Frame size includes headers and end byte (len(payload)+8), even if
@@ -978,9 +984,6 @@ func (c *Connection) openComplete() error {
 		_ = deadliner.SetDeadline(time.Time{})
 	}
 
-	c.m.Lock()
-	c.allocator = newAllocator(1, c.Config.ChannelMax)
-	c.m.Unlock()
 	return nil
 }
 

From c67e612737dc0810319965599bbbccea904d7315 Mon Sep 17 00:00:00 2001
From: Aitor Perez Cedres <acedres@vmware.com>
Date: Thu, 9 Feb 2023 10:29:41 +0000
Subject: [PATCH 2/2] Add a test case for usage of closed connection

After 2d55559, we are setting some fields to nil in the shutdown
sequence. We have to ensure that the library does not panic as a
consequence, after the connection is closed.

Signed-off-by: Aitor Perez Cedres <acedres@vmware.com>
---
 client_test.go | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/client_test.go b/client_test.go
index 815de15..e5a0154 100644
--- a/client_test.go
+++ b/client_test.go
@@ -288,7 +288,41 @@ func TestOpen(t *testing.T) {
 	if c, err := Open(rwc, defaultConfig()); err != nil {
 		t.Fatalf("could not create connection: %v (%s)", c, err)
 	}
+}
+
+func TestOpenClose_ShouldNotPanic(t *testing.T) {
+	rwc, srv := newSession(t)
+	t.Cleanup(func() {
+		_ = rwc.Close()
+	})
+
+	go func() {
+		srv.connectionOpen()
+		srv.connectionClose()
+	}()
+
+	c, err := Open(rwc, defaultConfig())
+	if err != nil {
+		t.Fatalf("could not create connection: %v (%s)", c, err)
+	}
+
+	if err := c.Close(); err != nil {
+		t.Fatalf("could not close connection: %s", err)
+	}
 
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("creating a channel on a closed connection should not panic: %s", r)
+		}
+	}()
+
+	ch, err := c.Channel()
+	if ch != nil {
+		t.Fatalf("creating a channel on a closed connection should not succeed: %v, (%s)", ch, err)
+	}
+	if err != ErrClosed {
+		t.Fatalf("error should be closed: %s", err)
+	}
 }
 
 func TestChannelOpen(t *testing.T) {