Fix ssh timeouts on nxos

CHANGELOG.md

@@ -13,7 +13,6 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 ### Changed
 - Refactored models: Use `keep_lines` and `reject_lines` in aosw, arubainstant, asa, efos, firelinuxos, fsos, ironware, mlnxos and perle to (@robertcheramy)
 - Refactor SSH and SCP into a common class SSHBase. Fixes #3597 (@robertcheramy)
-- SSH#disconnect directly calls @ssh.close, as #close waits for the channels to be closed anyway. This might have side effects, please open an issue if you observe a regression. (@robertcheramy)
 - Modified models to support store mode on significant changes: ios, fortios, perle (@robertcheramy)
 
 ### Fixed

lib/oxidized/input/ssh.rb

@@ -70,6 +70,21 @@ def pty_options(hash)
 
     private
 
+    # We need a specific disconnect for SSH in shell mode, see issue #3725
+    def disconnect
+      disconnect_cli
+      # if disconnect does not disconnect us, give up after timeout
+      Timeout.timeout(@node.timeout) { @ssh.loop }
+    rescue Errno::ECONNRESET, Net::SSH::Disconnect, IOError => e
+      logger.debug 'The other side closed the connection while ' \
+                   "disconnecting, raising #{e.class} with #{e.message}"
+    rescue Timeout::Error
+      logger.debug "#{@node.name} timed out while disconnecting"
+    ensure
+      @log.close if Oxidized.config.input.debug?
+      (@ssh.close rescue true) unless @ssh.closed? # rubocop:disable Style/RedundantParentheses
+    end
+
     def shell_open(ssh)
       @ses = ssh.open_channel do |ch|
         ch.on_data do |_ch, data|

spec/model/model_helper.rb

@@ -124,11 +124,6 @@ def loop(*)
     end
   end
 
-  def close
-    # Wait for the channels
-    loop
-  end
-
   def closed?
     false
   end