fix: use closed socket in io watcher

ev_epoll.c:134: epoll_modify: Assertion `("libev: I/O watcher with invalid fd found in epoll_ctl", errno != EBADF && errno != ELOOP && errno != EINVAL)`

Signed-off-by: Jianhui Zhao <zhaojh329@gmail.com>

src/http.c

@@ -40,6 +40,9 @@ static void send_http_msg(struct http_connection *conn, size_t len, uint8_t *dat
     struct rtty *rtty = conn->rtty;
     struct buffer *wb = &rtty->wb;
 
+    if (rtty->sock == -1)
+        return;
+
     buffer_put_u8(wb, MSG_TYPE_HTTP);
     buffer_put_u16be(wb, 18 + len);
     buffer_put_data(wb, conn->addr, 18);

src/rtty.c

@@ -314,10 +314,8 @@ void rtty_exit(struct rtty *rtty)
     }
 #endif
 
-    if (rtty->sock > 0) {
-        close(rtty->sock);
-        rtty->sock = -1;
-    }
+    close(rtty->sock);
+    rtty->sock = -1;
 
     http_conns_free(&rtty->http_conns);