Merge branch '1.15'

6 files changed, 91 insertions, 8 deletions

diff --git a/.travis.yml b/.travis.yml
index 9a55dbb6..45fb1722 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,8 +13,8 @@ install:
   - pip install coveralls # For coveralls.io specifically
   - pip install -r dev-requirements.txt
 script:
-  # Main tests, with coverage!
-  - inv test --coverage
+  # Main tests, w/ coverage! (but skip coverage on 3.2, coverage.py dropped it)
+  - "[[ $TRAVIS_PYTHON_VERSION != 3.2 ]] && inv test --coverage || inv test"
   # Ensure documentation & invoke pipeline run OK.
   # Run 'docs' first since its objects.inv is referred to by 'www'.
   # Also force warnings to be errors since most of them tend to be actual
diff --git a/paramiko/client.py b/paramiko/client.py
index e10e9da7..5a215a81 100644
--- a/paramiko/client.py
+++ b/paramiko/client.py
@@ -397,7 +397,7 @@ 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/packet.py b/paramiko/packet.py
index f516ff9b..b922000c 100644
--- a/paramiko/packet.py
+++ b/paramiko/packet.py
@@ -99,6 +99,10 @@ class Packetizer (object):
         self.__keepalive_last = time.time()
         self.__keepalive_callback = None
 
+        self.__timer = None
+        self.__handshake_complete = False
+        self.__timer_expired = False
+
     def set_log(self, log):
         """
         Set the Python log object to use for logging.
@@ -182,6 +186,45 @@ class Packetizer (object):
         self.__keepalive_callback = callback
         self.__keepalive_last = time.time()
 
+    def read_timer(self):
+        self.__timer_expired = True
+
+    def start_handshake(self, timeout):
+        """
+        Tells `Packetizer` that the handshake process started.
+        Starts a book keeping timer that can signal a timeout in the
+        handshake process.
+
+        :param float timeout: amount of seconds to wait before timing out
+        """
+        if not self.__timer:
+            self.__timer = threading.Timer(float(timeout), self.read_timer)
+            self.__timer.start()
+
+    def handshake_timed_out(self):
+        """
+        Checks if the handshake has timed out.
+        If `start_handshake` wasn't called before the call to this function
+        the return value will always be `False`.
+        If the handshake completed before a time out was reached the return value will be `False`
+
+        :return: handshake time out status, as a `bool`
+        """
+        if not self.__timer:
+            return False
+        if self.__handshake_complete:
+            return False
+        return self.__timer_expired
+
+    def complete_handshake(self):
+        """
+        Tells `Packetizer` that the handshake has completed.
+        """
+        if self.__timer:
+            self.__timer.cancel()
+            self.__timer_expired = False
+            self.__handshake_complete = True
+
     def read_all(self, n, check_rekey=False):
         """
         Read as close to N bytes as possible, blocking as long as necessary.
@@ -200,6 +243,8 @@ class Packetizer (object):
             n -= len(out)
         while n > 0:
             got_timeout = False
+            if self.handshake_timed_out():
+                raise EOFError()
             try:
                 x = self.__socket.recv(n)
                 if len(x) == 0:
diff --git a/paramiko/transport.py b/paramiko/transport.py
index 36da3043..31c27a2f 100644
--- a/paramiko/transport.py
+++ b/paramiko/transport.py
@@ -295,6 +295,8 @@ class Transport (threading.Thread, ClosingContextManager):
         self.global_response = None     # response Message from an arbitrary global request
         self.completion_event = None    # user-defined event callbacks
         self.banner_timeout = 15        # how long (seconds) to wait for the SSH banner
+        self.handshake_timeout = 15     # how long (seconds) to wait for the handshake to finish after SSH banner sent.
+
 
         # server mode:
         self.server_mode = False
@@ -587,7 +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
@@ -612,7 +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):
         """
@@ -659,7 +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
@@ -683,17 +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)
@@ -722,6 +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:
@@ -731,6 +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
@@ -1582,6 +1592,12 @@ class Transport (threading.Thread, ClosingContextManager):
             try:
                 self.packetizer.write_all(b(self.local_version + '\r\n'))
                 self._check_banner()
+                # The above is actually very much part of the handshake, but sometimes the banner can be read
+                # but the machine is not responding, for example when the remote ssh daemon is loaded in to memory
+                # but we can not read from the disk/spawn a new shell.
+                # Make sure we can specify a timeout for the initial handshake.
+                # Re-use the banner timeout for now.
+                self.packetizer.start_handshake(self.handshake_timeout)
                 self._send_kex_init()
                 self._expect_packet(MSG_KEXINIT)
 
@@ -1631,6 +1647,7 @@ class Transport (threading.Thread, ClosingContextManager):
                         msg.add_byte(cMSG_UNIMPLEMENTED)
                         msg.add_int(m.seqno)
                         self._send_message(msg)
+                    self.packetizer.complete_handshake()
             except SSHException as e:
                 self._log(ERROR, 'Exception: ' + str(e))
                 self._log(ERROR, util.tb_strings())
diff --git a/sites/www/changelog.rst b/sites/www/changelog.rst
index fb09b7a1..bbc89b75 100644
--- a/sites/www/changelog.rst
+++ b/sites/www/changelog.rst
@@ -2,6 +2,10 @@
 Changelog
 =========
 
+* :bug:`491` (combines :issue:`62` and :issue:`439`) Implement timeout
+  functionality to address hangs from dropped network connections and/or failed
+  handshakes. Credit to ``@vazir`` and ``@dacut`` for the original patches and
+  to Olle Lundberg for reimplementation.
 * :bug:`490` Skip invalid/unparseable lines in ``known_hosts`` files, instead
   of raising `SSHException`. This brings Paramiko's behavior more in line with
   OpenSSH, which silently ignores such input. Catch & patch courtesy of Martin
diff --git a/tests/test_transport.py b/tests/test_transport.py
index 5cf9a867..3c8ad81e 100644
--- a/tests/test_transport.py
+++ b/tests/test_transport.py
@@ -792,3 +792,20 @@ class TransportTest(unittest.TestCase):
                              (None, DEFAULT_WINDOW_SIZE),
                              (2**32, MAX_WINDOW_SIZE)]:
             self.assertEqual(self.tc._sanitize_window_size(val), correct)
+
+    def test_L_handshake_timeout(self):
+        """
+        verify that we can get a hanshake timeout.
+        """
+        host_key = RSAKey.from_private_key_file(test_path('test_rsa.key'))
+        public_host_key = RSAKey(data=host_key.asbytes())
+        self.ts.add_server_key(host_key)
+        event = threading.Event()
+        server = NullServer()
+        self.assertTrue(not event.is_set())
+        self.tc.handshake_timeout = 0.000000000001
+        self.ts.start_server(event, server)
+        self.assertRaises(EOFError, self.tc.connect,
+                          hostkey=public_host_key,
+                          username='slowdive',
+                          password='pygmalion')