[project @ Arch-1:robey@lag.net--2003-public%secsh--dev--1.0--patch-66]

new ServerInterface class, outbound rekey works, etc.
a bunch of changes that i'm too lazy to split out into individual patches:
* all the server overrides from transport.py have been moved into a separate
  class ServerInterface, so server code doesn't have to subclass the whole
  paramiko library
* updated demo_server to subclass ServerInterface
* when re-keying during a session, block other messages until the new keys
  are activated (openssh doensn't like any other traffic during a rekey)
* re-key when outbound limits are tripped too (was only counting inbound
  traffic)
* don't log scary things on EOF

6 files changed, 249 insertions, 170 deletions

diff --git a/README b/README
index 173533c9..8958519f 100644
--- a/README
+++ b/README
@@ -155,4 +155,3 @@ v0.9 FEAROW
 * multi-part auth not supported (ie, need username AND pk)
 * server mode needs better documentation
 * sftp server mode
-* make invoke_subsystem, etc wait for a reply
diff --git a/demo_server.py b/demo_server.py
index 5d6cbb5c..8d889963 100755
--- a/demo_server.py
+++ b/demo_server.py
@@ -15,7 +15,7 @@ host_key.read_private_key_file('demo_dss_key')
 print 'Read key: ' + paramiko.util.hexify(host_key.get_fingerprint())
 
 
-class ServerTransport(paramiko.Transport):
+class Server (paramiko.ServerInterface):
     # 'data' is the output of base64.encodestring(str(key))
     data = 'AAAAB3NzaC1yc2EAAAABIwAAAIEAyO4it3fHlmGZWJaGrfeHOVY7RWO3P9M7hpfAu7jJ2d7eothvfeuoRFtJwhUmZDluRdFyhFY/hFAh76PJKGAusIqIQKlkJxMCKDqIexkgHAfID/6mqvmnSJf0b5W8v5h2pI/stOSwTQ+pxVhwJ9ctYDhRSlF0iTUWT10hcuO4Ks8='
     good_pub_key = paramiko.RSAKey(data=base64.decodestring(data))
@@ -23,24 +23,24 @@ class ServerTransport(paramiko.Transport):
     def check_channel_request(self, kind, chanid):
         if kind == 'session':
             return ServerChannel(chanid)
-        return self.OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
+        return paramiko.Transport.OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
 
     def check_auth_password(self, username, password):
         if (username == 'robey') and (password == 'foo'):
-            return self.AUTH_SUCCESSFUL
-        return self.AUTH_FAILED
+            return paramiko.Transport.AUTH_SUCCESSFUL
+        return paramiko.Transport.AUTH_FAILED
 
     def check_auth_publickey(self, username, key):
         print 'Auth attempt with key: ' + paramiko.util.hexify(key.get_fingerprint())
         if (username == 'robey') and (key == self.good_pub_key):
-            return self.AUTH_SUCCESSFUL
-        return self.AUTH_FAILED
+            return paramiko.Transport.AUTH_SUCCESSFUL
+        return paramiko.Transport.AUTH_FAILED
 
     def get_allowed_auths(self, username):
         return 'password,publickey'
 
 
-class ServerChannel(paramiko.Channel):
+class ServerChannel (paramiko.Channel):
     "Channel descendant that pretends to understand pty and shell requests"
 
     def __init__(self, chanid):
@@ -61,7 +61,6 @@ try:
     sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
     sock.bind(('', 2200))
 except Exception, e:
-
     print '*** Bind failed: ' + str(e)
     traceback.print_exc()
     sys.exit(1)
@@ -79,14 +78,14 @@ print 'Got a connection!'
 
 try:
     event = threading.Event()
-    t = ServerTransport(client)
+    t = paramiko.Transport(client)
     try:
         t.load_server_moduli()
     except:
         print '(Failed to load moduli -- gex will be unsupported.)'
         raise
     t.add_server_key(host_key)
-    t.start_server(event)
+    t.start_server(event, Server())
     while 1:
         event.wait(0.1)
         if not t.is_active():
diff --git a/paramiko/__init__.py b/paramiko/__init__.py
index 5d2925ef..c987af24 100644
--- a/paramiko/__init__.py
+++ b/paramiko/__init__.py
@@ -76,6 +76,7 @@ SSHException = ssh_exception.SSHException
 Message = message.Message
 PasswordRequiredException = ssh_exception.PasswordRequiredException
 SFTP = sftp.SFTP
+ServerInterface = server.ServerInterface
 
 
 __all__ = [ 'Transport',
@@ -86,6 +87,7 @@ __all__ = [ 'Transport',
             'SSHException',
             'PasswordRequiredException',
             'SFTP',
+            'ServerInterface',
             'transport',
             'auth_transport',
             'channel',
@@ -95,4 +97,5 @@ __all__ = [ 'Transport',
             'message',
             'ssh_exception',
             'sftp',
+            'server',
             'util' ]
diff --git a/paramiko/auth_transport.py b/paramiko/auth_transport.py
index 048e3f02..55f63633 100644
--- a/paramiko/auth_transport.py
+++ b/paramiko/auth_transport.py
@@ -156,102 +156,6 @@ class Transport (BaseTransport):
         finally:
             self.lock.release()
 
-    def get_allowed_auths(self, username):
-        """
-        I{(subclass override)}
-        Return a list of authentication methods supported by the server.
-        This list is sent to clients attempting to authenticate, to inform them
-        of authentication methods that might be successful.
-
-        The "list" is actually a string of comma-separated names of types of
-        authentication.  Possible values are C{"password"}, C{"publickey"},
-        and C{"none"}.
-
-        The default implementation always returns C{"password"}.
-
-        @param username: the username requesting authentication.
-        @type username: string
-        @return: a comma-separated list of authentication types
-        @rtype: string
-        """
-        return 'password'
-
-    def check_auth_none(self, username):
-        """
-        I{(subclass override)}
-        Determine if a client may open channels with no (further)
-        authentication.  You should override this method in server mode.
-
-        Return C{AUTH_FAILED} if the client must authenticate, or
-        C{AUTH_SUCCESSFUL} if it's okay for the client to not authenticate.
-
-        The default implementation always returns C{AUTH_FAILED}.
-
-        @param username: the username of the client.
-        @type username: string
-        @return: C{AUTH_FAILED} if the authentication fails; C{AUTH_SUCCESSFUL}
-        if it succeeds.
-        @rtype: int
-        """
-        return self.AUTH_FAILED
-
-    def check_auth_password(self, username, password):
-        """
-        I{(subclass override)}
-        Determine if a given username and password supplied by the client is
-        acceptable for use in authentication.  You should override this method
-        in server mode.
-
-        Return C{AUTH_FAILED} if the password is not accepted,
-        C{AUTH_SUCCESSFUL} if the password is accepted and completes the
-        authentication, or C{AUTH_PARTIALLY_SUCCESSFUL} if your authentication
-        is stateful, and this key is accepted for authentication, but more
-        authentication is required.  (In this latter case, L{get_allowed_auths}
-        will be called to report to the client what options it has for
-        continuing the authentication.)
-
-        The default implementation always returns C{AUTH_FAILED}.
-
-        @param username: the username of the authenticating client.
-        @type username: string
-        @param password: the password given by the client.
-        @type password: string
-        @return: C{AUTH_FAILED} if the authentication fails; C{AUTH_SUCCESSFUL}
-        if it succeeds; C{AUTH_PARTIALLY_SUCCESSFUL} if the password auth is
-        successful, but authentication must continue.
-        @rtype: int
-        """
-        return self.AUTH_FAILED
-
-    def check_auth_publickey(self, username, key):
-        """
-        I{(subclass override)}
-        Determine if a given key supplied by the client is acceptable for use
-        in authentication.  You should override this method in server mode to
-        check the username and key and decide if you would accept a signature
-        made using this key.
-
-        Return C{AUTH_FAILED} if the key is not accepted, C{AUTH_SUCCESSFUL}
-        if the key is accepted and completes the authentication, or
-        C{AUTH_PARTIALLY_SUCCESSFUL} if your authentication is stateful, and
-        this key is accepted for authentication, but more authentication is
-        required.  (In this latter case, L{get_allowed_auths} will be called
-        to report to the client what options it has for continuing the
-        authentication.)
-
-        The default implementation always returns C{AUTH_FAILED}.
-
-        @param username: the username of the authenticating client.
-        @type username: string
-        @param key: the key object provided by the client.
-        @type key: L{PKey <pkey.PKey>}
-        @return: C{AUTH_FAILED} if the client can't authenticate with this key;
-        C{AUTH_SUCCESSFUL} if it can; C{AUTH_PARTIALLY_SUCCESSFUL} if it can
-        authenticate with this key but must continue with authentication.
-        @rtype: int
-        """
-        return self.AUTH_FAILED
-
 
     ###  internals...
 
@@ -355,7 +259,7 @@ class Transport (BaseTransport):
         self.auth_username = username
 
         if method == 'none':
-            result = self.check_auth_none(username)
+            result = self.server_object.check_auth_none(username)
         elif method == 'password':
             changereq = m.get_boolean()
             password = m.get_string().decode('UTF-8')
@@ -366,7 +270,7 @@ class Transport (BaseTransport):
                 newpassword = m.get_string().decode('UTF-8')
                 result = self.AUTH_FAILED
             else:
-                result = self.check_auth_password(username, password)
+                result = self.server_object.check_auth_password(username, password)
         elif method == 'publickey':
             sig_attached = m.get_boolean()
             keytype = m.get_string()
@@ -377,7 +281,7 @@ class Transport (BaseTransport):
                 self._disconnect_no_more_auth()
                 return
             # first check if this key is okay... if not, we can skip the verify
-            result = self.check_auth_publickey(username, key)
+            result = self.server_object.check_auth_publickey(username, key)
             if result != self.AUTH_FAILED:
                 # key is okay, verify it
                 if not sig_attached:
@@ -395,7 +299,7 @@ class Transport (BaseTransport):
                     self._log(DEBUG, 'Auth rejected: invalid signature')
                     result = self.AUTH_FAILED
         else:
-            result = self.check_auth_none(username)
+            result = self.server_object.check_auth_none(username)
         # okay, send result
         m = Message()
         if result == self.AUTH_SUCCESSFUL:
@@ -405,7 +309,7 @@ class Transport (BaseTransport):
         else:
             self._log(DEBUG, 'Auth rejected.')
             m.add_byte(chr(MSG_USERAUTH_FAILURE))
-            m.add_string(self.get_allowed_auths(username))
+            m.add_string(self.server_object.get_allowed_auths(username))
             if result == self.AUTH_PARTIALLY_SUCCESSFUL:
                 m.add_boolean(1)
             else:
diff --git a/paramiko/server.py b/paramiko/server.py
new file mode 100644
index 00000000..6abcffbf
--- /dev/null
+++ b/paramiko/server.py
@@ -0,0 +1,154 @@
+#!/usr/bin/python
+
+# Copyright (C) 2003-2004 Robey Pointer <robey@lag.net>
+#
+# This file is part of paramiko.
+#
+# Paramiko is free software; you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation; either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+
+"""
+L{ServerInterface} is an interface to override for server support.
+"""
+
+from auth_transport import Transport
+
+class ServerInterface (object):
+    """
+    This class defines an interface for controlling the behavior of paramiko
+    in server mode.
+    """
+
+    def check_channel_request(self, kind, chanid):
+        """
+        Determine if a channel request of a given type will be granted, and
+        return a suitable L{Channel} object.  This method is called in server
+        mode when the client requests a channel, after authentication is
+        complete.
+
+        You will generally want to subclass L{Channel} to override some of the
+        methods for handling client requests (such as connecting to a subsystem
+        opening a shell) to determine what you want to allow or disallow.  For
+        this reason, L{check_channel_request} must return a new object of that
+        type.  The C{chanid} parameter is passed so that you can use it in
+        L{Channel}'s constructor.
+
+        The default implementation always returns C{None}, rejecting any
+        channel requests.  A useful server must override this method.
+
+        @param kind: the kind of channel the client would like to open
+        (usually C{"session"}).
+        @type kind: string
+        @param chanid: ID of the channel, required to create a new L{Channel}
+        object.
+        @type chanid: int
+        @return: a new L{Channel} object (or subclass thereof), or C{None} to
+        refuse the request.
+        @rtype: L{Channel}
+        """
+        return None
+
+    def get_allowed_auths(self, username):
+        """
+        Return a list of authentication methods supported by the server.
+        This list is sent to clients attempting to authenticate, to inform them
+        of authentication methods that might be successful.
+
+        The "list" is actually a string of comma-separated names of types of
+        authentication.  Possible values are C{"password"}, C{"publickey"},
+        and C{"none"}.
+
+        The default implementation always returns C{"password"}.
+
+        @param username: the username requesting authentication.
+        @type username: string
+        @return: a comma-separated list of authentication types
+        @rtype: string
+        """
+        return 'password'
+
+    def check_auth_none(self, username):
+        """
+        Determine if a client may open channels with no (further)
+        authentication.
+
+        Return L{Transport.AUTH_FAILED} if the client must authenticate, or
+        L{Transport.AUTH_SUCCESSFUL} if it's okay for the client to not
+        authenticate.
+
+        The default implementation always returns L{Transport.AUTH_FAILED}.
+
+        @param username: the username of the client.
+        @type username: string
+        @return: L{Transport.AUTH_FAILED} if the authentication fails;
+        L{Transport.AUTH_SUCCESSFUL} if it succeeds.
+        @rtype: int
+        """
+        return Transport.AUTH_FAILED
+
+    def check_auth_password(self, username, password):
+        """
+        Determine if a given username and password supplied by the client is
+        acceptable for use in authentication.
+
+        Return L{Transport.AUTH_FAILED} if the password is not accepted,
+        L{Transport.AUTH_SUCCESSFUL} if the password is accepted and completes
+        the authentication, or L{Transport.AUTH_PARTIALLY_SUCCESSFUL} if your
+        authentication is stateful, and this key is accepted for
+        authentication, but more authentication is required.  (In this latter
+        case, L{get_allowed_auths} will be called to report to the client what
+        options it has for continuing the authentication.)
+
+        The default implementation always returns L{Transport.AUTH_FAILED}.
+
+        @param username: the username of the authenticating client.
+        @type username: string
+        @param password: the password given by the client.
+        @type password: string
+        @return: L{Transport.AUTH_FAILED} if the authentication fails;
+        L{Transport.AUTH_SUCCESSFUL} if it succeeds;
+        L{Transport.AUTH_PARTIALLY_SUCCESSFUL} if the password auth is
+        successful, but authentication must continue.
+        @rtype: int
+        """
+        return Transport.AUTH_FAILED
+
+    def check_auth_publickey(self, username, key):
+        """
+        Determine if a given key supplied by the client is acceptable for use
+        in authentication.  You should override this method in server mode to
+        check the username and key and decide if you would accept a signature
+        made using this key.
+
+        Return L{Transport.AUTH_FAILED} if the key is not accepted,
+        L{Transport.AUTH_SUCCESSFUL} if the key is accepted and completes the
+        authentication, or L{Transport.AUTH_PARTIALLY_SUCCESSFUL} if your
+        authentication is stateful, and this key is accepted for
+        authentication, but more authentication is required.  (In this latter
+        case, L{get_allowed_auths} will be called to report to the client what
+        options it has for continuing the authentication.)
+
+        The default implementation always returns L{Transport.AUTH_FAILED}.
+
+        @param username: the username of the authenticating client.
+        @type username: string
+        @param key: the key object provided by the client.
+        @type key: L{PKey <pkey.PKey>}
+        @return: L{Transport.AUTH_FAILED} if the client can't authenticate
+        with this key; L{Transport.AUTH_SUCCESSFUL} if it can;
+        L{Transport.AUTH_PARTIALLY_SUCCESSFUL} if it can authenticate with
+        this key but must continue with authentication.
+        @rtype: int
+        """
+        return Transport.AUTH_FAILED
diff --git a/paramiko/transport.py b/paramiko/transport.py
index 06f75801..7931a11f 100644
--- a/paramiko/transport.py
+++ b/paramiko/transport.py
@@ -138,6 +138,9 @@ class BaseTransport (threading.Thread):
         self.sock = sock
         # Python < 2.3 doesn't have the settimeout method - RogerB
         try:
+            # we set the timeout so we can check self.active periodically to
+            # see if we should bail.  socket.timeout exception is never
+            # propagated.
             self.sock.settimeout(0.1)
         except AttributeError:
             pass
@@ -155,7 +158,7 @@ class BaseTransport (threading.Thread):
         self.expected_packet = 0
         self.active = False
         self.initial_kex_done = False
-        self.write_lock = threading.Lock()	# lock around outbound writes (packet computation)
+        self.write_lock = threading.RLock()	# lock around outbound writes (packet computation)
         self.lock = threading.Lock()		# synchronization (always higher level than write_lock)
         self.channels = { }			# (id -> Channel)
         self.channel_events = { }		# (id -> Event)
@@ -165,10 +168,13 @@ class BaseTransport (threading.Thread):
         self.max_packet_size = 32768
         self.ultra_debug = False
         self.saved_exception = None
+        self.clear_to_send = threading.Event()
         # used for noticing when to re-key:
         self.received_bytes = 0
         self.received_packets = 0
         self.received_packets_overflow = 0
+        self.sent_bytes = 0
+        self.sent_packets = 0
         # user-defined event callbacks:
         self.completion_event = None
         # keepalives:
@@ -176,6 +182,7 @@ class BaseTransport (threading.Thread):
         self.keepalive_last = time.time()
         # server mode:
         self.server_mode = 0
+        self.server_object = None
         self.server_key_dict = { }
         self.server_accepts = [ ]
         self.server_accept_cv = threading.Condition(self.lock)
@@ -223,7 +230,7 @@ class BaseTransport (threading.Thread):
         self.completion_event = event
         self.start()
 
-    def start_server(self, event=None):
+    def start_server(self, event=None, server=None):
         """
         Negotiate a new SSH2 session as a server.  This is the first step after
         creating a new L{Transport} and setting up your server host key(s).  A
@@ -235,15 +242,16 @@ class BaseTransport (threading.Thread):
 
         After a successful negotiation, the client will need to authenticate.
         Override the methods
-        L{get_allowed_auths <Transport.get_allowed_auths>},
-        L{check_auth_none <Transport.check_auth_none>},
-        L{check_auth_password <Transport.check_auth_password>}, and
-        L{check_auth_publickey <Transport.check_auth_publickey>} to control the
-        authentication process.
+        L{get_allowed_auths <ServerInterface.get_allowed_auths>},
+        L{check_auth_none <ServerInterface.check_auth_none>},
+        L{check_auth_password <ServerInterface.check_auth_password>}, and
+        L{check_auth_publickey <ServerInterface.check_auth_publickey>} in the
+        given C{server} object to control the authentication process.
 
         After a successful authentication, the client should request to open
-        a channel.  Override L{check_channel_request} to allow channels to
-        be opened.
+        a channel.  Override
+        L{check_channel_request <ServerInterface.check_channel_request>} in the
+        given C{server} object to allow channels to be opened.
 
         @note: After calling this method (or L{start_client} or L{connect}),
         you should no longer directly read from or write to the original socket
@@ -251,8 +259,14 @@ class BaseTransport (threading.Thread):
 
         @param event: an event to trigger when negotiation is complete.
         @type event: threading.Event
+        @param server: an object used to perform authentication and create
+        L{Channel}s.
+        @type server: L{server.ServerInterface}
         """
+        if server is None:
+            server = ServerInterface()
         self.server_mode = 1
+        self.server_object = server
         self.completion_event = event
         self.start()
 
@@ -422,7 +436,7 @@ class BaseTransport (threading.Thread):
             self.channel_events[chanid] = event = threading.Event()
             chan._set_transport(self)
             chan._set_window(self.window_size, self.max_packet_size)
-            self._send_message(m)
+            self._send_user_message(m)
         finally:
             self.lock.release()
         while 1:
@@ -457,7 +471,7 @@ class BaseTransport (threading.Thread):
         if bytes is None:
             bytes = (ord(randpool.get_bytes(1)) % 32) + 10
         m.add_bytes(randpool.get_bytes(bytes))
-        self._send_message(m)
+        self._send_user_message(m)
 
     def renegotiate_keys(self):
         """
@@ -528,7 +542,7 @@ class BaseTransport (threading.Thread):
             for item in data:
                 m.add(item)
         self._log(DEBUG, 'Sending global request "%s"' % kind)
-        self._send_message(m)
+        self._send_user_message(m)
         if not wait:
             return True
         while True:
@@ -539,36 +553,6 @@ class BaseTransport (threading.Thread):
                 break
         return self.global_response
 
-    def check_channel_request(self, kind, chanid):
-        """
-        I{(subclass override)}
-        Determine if a channel request of a given type will be granted, and
-        return a suitable L{Channel} object.  This method is called in server
-        mode when the client requests a channel, after authentication is
-        complete.
-
-        In server mode, you will generally want to subclass L{Channel} to
-        override some of the methods for handling client requests (such as
-        connecting to a subsystem or opening a shell) to determine what you
-        want to allow or disallow.  For this reason, L{check_channel_request}
-        must return a new object of that type.  The C{chanid} parameter is
-        passed so that you can use it in L{Channel}'s constructor.
-
-        The default implementation always returns C{None}, rejecting any
-        channel requests.  A useful server must override this method.
-
-        @param kind: the kind of channel the client would like to open
-        (usually C{"session"}).
-        @type kind: string
-        @param chanid: ID of the channel, required to create a new L{Channel}
-        object.
-        @type chanid: int
-        @return: a new L{Channel} object (or subclass thereof), or C{None} to
-        refuse the request.
-        @rtype: L{Channel}
-        """
-        return None
-
     def check_global_request(self, kind, msg):
         """
         I{(subclass override)}
@@ -771,7 +755,11 @@ class BaseTransport (threading.Thread):
     def _write_all(self, out):
         self.keepalive_last = time.time()
         while len(out) > 0:
-            n = self.sock.send(out)
+            try:
+                n = self.sock.send(out)
+            except:
+                # could be: (32, 'Broken pipe')
+                n = -1
             if n < 0:
                 raise EOFError()
             if n == len(out):
@@ -810,9 +798,33 @@ class BaseTransport (threading.Thread):
             self.sequence_number_out += 1L
             self.sequence_number_out %= 0x100000000L
             self._write_all(out)
+
+            self.sent_bytes += len(out)
+            self.sent_packets += 1
+            if ((self.sent_packets >= self.REKEY_PACKETS) or (self.sent_bytes >= self.REKEY_BYTES)) \
+                   and (self.local_kex_init is None):
+                # only ask once for rekeying
+                self._log(DEBUG, 'Rekeying (hit %d packets, %d bytes sent)' %
+                          (self.sent_packets, self.sent_bytes))
+                self.received_packets_overflow = 0
+                self._send_kex_init()
         finally:
             self.write_lock.release()
 
+    def _send_user_message(self, data):
+        """
+        send a message, but block if we're in key negotiation.  this is used
+        for user-initiated requests.
+        """
+        while 1:
+            self.clear_to_send.wait(0.1)
+            if not self.active:
+                self._log(DEBUG, 'Dropping user packet because connection is dead.')
+                return
+            if self.clear_to_send.isSet():
+                break
+        self._send_message(data)
+
     def _read_message(self):
         "only one thread will ever be in this function"
         header = self._read_all(self.block_size_in)
@@ -850,19 +862,19 @@ class BaseTransport (threading.Thread):
         # check for rekey
         self.received_bytes += packet_size + self.remote_mac_len + 4
         self.received_packets += 1
-        if (self.received_packets >= self.REKEY_PACKETS) or (self.received_bytes >= self.REKEY_BYTES):
+        if self.local_kex_init is not None:
+            # we've asked to rekey -- give them 20 packets to comply before
+            # dropping the connection
+            self.received_packets_overflow += 1
+            if self.received_packets_overflow >= 20:
+                raise SSHException('Remote transport is ignoring rekey requests')
+        elif (self.received_packets >= self.REKEY_PACKETS) or \
+             (self.received_bytes >= self.REKEY_BYTES):
             # only ask once for rekeying
-            if self.local_kex_init is None:
-                self._log(DEBUG, 'Rekeying (hit %d packets, %d bytes)' % (self.received_packets,
-                                                                          self.received_bytes))
-                self.received_packets_overflow = 0
-                self._send_kex_init()
-            else:
-                # we've asked to rekey already -- give them 20 packets to
-                # comply, then just drop the connection
-                self.received_packets_overflow += 1
-                if self.received_packets_overflow >= 20:
-                    raise SSHException('Remote transport is ignoring rekey requests')
+            self._log(DEBUG, 'Rekeying (hit %d packets, %d bytes received)' %
+                      (self.received_packets, self.received_bytes))
+            self.received_packets_overflow = 0
+            self._send_kex_init()
 
         cmd = ord(payload[0])
         self._log(DEBUG, 'Read packet $%x, length %d' % (cmd, len(payload)))
@@ -964,8 +976,8 @@ class BaseTransport (threading.Thread):
             self._log(ERROR, util.tb_strings())
             self.saved_exception = e
         except EOFError, e:
-            self._log(DEBUG, 'EOF')
-            self._log(DEBUG, util.tb_strings())
+            self._log(DEBUG, 'EOF in transport thread')
+            #self._log(DEBUG, util.tb_strings())
             self.saved_exception = e
         except Exception, e:
             self._log(ERROR, 'Unknown exception: ' + str(e))
@@ -990,6 +1002,7 @@ class BaseTransport (threading.Thread):
 
     def _negotiate_keys(self, m):
         # throws SSHException on anything unusual
+        self.clear_to_send.clear()
         if self.local_kex_init == None:
             # remote side wants to renegotiate
             self._send_kex_init()
@@ -1033,6 +1046,7 @@ class BaseTransport (threading.Thread):
         announce to the other side that we'd like to negotiate keys, and what
         kind of key negotiation we support.
         """
+        self.clear_to_send.clear()
         if self.server_mode:
             if (self._modulus_pack is None) and ('diffie-hellman-group-exchange-sha1' in self.preferred_kex):
                 # can't do group-exchange if we don't have a pack of potential primes
@@ -1066,6 +1080,8 @@ class BaseTransport (threading.Thread):
         self.received_bytes = 0
         self.received_packets = 0
         self.received_packets_overflow = 0
+        self.sent_bytes = 0
+        self.sent_packets = 0
 
         cookie = m.get_bytes(16)
         kex_algo_list = m.get_list()
@@ -1211,6 +1227,8 @@ class BaseTransport (threading.Thread):
         # send an event?
         if self.completion_event != None:
             self.completion_event.set()
+        # it's now okay to send data again (if this was a re-key)
+        self.clear_to_send.set()
         return
 
     def _parse_disconnect(self, m):
@@ -1307,7 +1325,7 @@ class BaseTransport (threading.Thread):
                 self.channel_counter += 1
             finally:
                 self.lock.release()
-            chan = self.check_channel_request(kind, my_chanid)
+            chan = self.server_object.check_channel_request(kind, my_chanid)
             if (chan is None) or (type(chan) is int):
                 self._log(DEBUG, 'Rejecting "%s" channel request from client.' % kind)
                 reject = True
@@ -1373,3 +1391,5 @@ class BaseTransport (threading.Thread):
         MSG_CHANNEL_EOF: Channel._handle_eof,
         MSG_CHANNEL_CLOSE: Channel._handle_close,
         }
+
+from server import ServerInterface