Patch resolving the timeout issue on lost conection.

(This rolls in patch in #439)

3 files changed, 17 insertions, 6 deletions

diff --git a/paramiko/client.py b/paramiko/client.py
index 393e3e09..9ee30287 100644
--- a/paramiko/client.py
+++ b/paramiko/client.py
@@ -338,7 +338,7 @@ class SSHClient (ClosingContextManager):
 
         :raises SSHException: if the server fails to execute the command
         """
-        chan = self._transport.open_session()
+        chan = self._transport.open_session(timeout=timeout)
         if get_pty:
             chan.get_pty()
         chan.settimeout(timeout)
diff --git a/paramiko/transport.py b/paramiko/transport.py
index 6047fb99..31c27a2f 100644
--- a/paramiko/transport.py
+++ b/paramiko/transport.py
@@ -589,7 +589,7 @@ class Transport (threading.Thread, ClosingContextManager):
         """
         return self.active
 
-    def open_session(self, window_size=None, max_packet_size=None):
+    def open_session(self, window_size=None, max_packet_size=None, timeout=None):
         """
         Request a new channel to the server, of type ``"session"``.  This is
         just an alias for calling `open_channel` with an argument of
@@ -614,7 +614,8 @@ class Transport (threading.Thread, ClosingContextManager):
         """
         return self.open_channel('session',
                                  window_size=window_size,
-                                 max_packet_size=max_packet_size)
+                                 max_packet_size=max_packet_size,
+                                 timeout=timeout)
 
     def open_x11_channel(self, src_addr=None):
         """
@@ -661,7 +662,8 @@ class Transport (threading.Thread, ClosingContextManager):
                      dest_addr=None,
                      src_addr=None,
                      window_size=None,
-                     max_packet_size=None):
+                     max_packet_size=None,
+                     timeout=None):
         """
         Request a new channel to the server. `Channels <.Channel>` are
         socket-like objects used for the actual transfer of data across the
@@ -685,17 +687,20 @@ class Transport (threading.Thread, ClosingContextManager):
             optional window size for this session.
         :param int max_packet_size:
             optional max packet size for this session.
+        :param float timeout:
+            optional timeout opening a channel, default 3600s (1h)
 
         :return: a new `.Channel` on success
 
-        :raises SSHException: if the request is rejected or the session ends
-            prematurely
+        :raises SSHException: if the request is rejected, the session ends
+            prematurely or there is a timeout openning a channel
 
         .. versionchanged:: 1.15
             Added the ``window_size`` and ``max_packet_size`` arguments.
         """
         if not self.active:
             raise SSHException('SSH session not active')
+        timeout = 3600 if timeout is None else timeout
         self.lock.acquire()
         try:
             window_size = self._sanitize_window_size(window_size)
@@ -724,6 +729,7 @@ class Transport (threading.Thread, ClosingContextManager):
         finally:
             self.lock.release()
         self._send_user_message(m)
+        start_ts = time.time()
         while True:
             event.wait(0.1)
             if not self.active:
@@ -733,6 +739,8 @@ class Transport (threading.Thread, ClosingContextManager):
                 raise e
             if event.is_set():
                 break
+            elif start_ts + timeout < time.time():
+                raise SSHException('Timeout openning channel.')
         chan = self._channels.get(chanid)
         if chan is not None:
             return chan
diff --git a/sites/www/changelog.rst b/sites/www/changelog.rst
index f9900327..16a60a68 100644
--- a/sites/www/changelog.rst
+++ b/sites/www/changelog.rst
@@ -2,6 +2,9 @@
 Changelog
 =========
 
+* :bug:`439` Resolve the timeout issue on lost conection.
+  When the destination disappears on an established session paramiko will hang on trying to open a channel.
+  Credit to ``@vazir`` for patch.
 * :bug:`62` Add timeout for handshake completion.
   This adds a mechanism for timing out a connection if the ssh handshake
   never completes.