netconn.go: Fix panic on zero or negative deadline durations

Glad no one ran into this in production.

Author: nhooyr

conn_test.go

@@ -236,6 +236,18 @@ func TestConn(t *testing.T) {
 		assert.Equal(t, "read msg", s, string(b))
 	})
 
+	t.Run("netConn/pastDeadline", func(t *testing.T) {
+		tt, c1, c2 := newConnTest(t, nil, nil)
+
+		n1 := websocket.NetConn(tt.ctx, c1, websocket.MessageBinary)
+		n2 := websocket.NetConn(tt.ctx, c2, websocket.MessageBinary)
+
+		n1.SetDeadline(time.Now().Add(-time.Minute))
+		n2.SetDeadline(time.Now().Add(-time.Minute))
+
+		// No panic we're good.
+	})
+
 	t.Run("wsjson", func(t *testing.T) {
 		tt, c1, c2 := newConnTest(t, nil, nil)
 

netconn.go

@@ -210,7 +210,11 @@ func (nc *netConn) SetWriteDeadline(t time.Time) error {
 	if t.IsZero() {
 		nc.writeTimer.Stop()
 	} else {
-		nc.writeTimer.Reset(time.Until(t))
+		dur := time.Until(t)
+		if dur <= 0 {
+			dur = 1
+		}
+		nc.writeTimer.Reset(dur)
 	}
 	return nil
 }
@@ -220,7 +224,11 @@ func (nc *netConn) SetReadDeadline(t time.Time) error {
 	if t.IsZero() {
 		nc.readTimer.Stop()
 	} else {
-		nc.readTimer.Reset(time.Until(t))
+		dur := time.Until(t)
+		if dur <= 0 {
+			dur = 1
+		}
+		nc.readTimer.Reset(dur)
 	}
 	return nil
 }