Move window and packet constants.

Centralise them to the common module to avoid import cycles.
Also add constants for default values and use them in the
transport class.

3 files changed, 17 insertions, 13 deletions

diff --git a/paramiko/channel.py b/paramiko/channel.py
index 90761d43..d6ad1a52 100644
--- a/paramiko/channel.py
+++ b/paramiko/channel.py
@@ -30,7 +30,7 @@ from paramiko import util
 from paramiko.common import cMSG_CHANNEL_REQUEST, cMSG_CHANNEL_WINDOW_ADJUST, \
     cMSG_CHANNEL_DATA, cMSG_CHANNEL_EXTENDED_DATA, DEBUG, ERROR, \
     cMSG_CHANNEL_SUCCESS, cMSG_CHANNEL_FAILURE, cMSG_CHANNEL_EOF, \
-    cMSG_CHANNEL_CLOSE
+    cMSG_CHANNEL_CLOSE, MIN_PACKET_SIZE
 from paramiko.message import Message
 from paramiko.py3compat import bytes_types
 from paramiko.ssh_exception import SSHException
@@ -39,14 +39,6 @@ from paramiko.buffered_pipe import BufferedPipe, PipeTimeout
 from paramiko import pipe
 
 
-# lower bound on the max packet size we'll accept from the remote host
-# Minimum packet size is 32768 bytes according to
-# http://www.ietf.org/rfc/rfc4254.txt
-MIN_PACKET_SIZE = 2 ** 15
-
-# Max windows size according to http://www.ietf.org/rfc/rfc4254.txt
-MAX_WINDOW_SIZE = 2**32 -1
-
 class Channel (object):
     """
     A secure tunnel across an SSH `.Transport`.  A Channel is meant to behave
diff --git a/paramiko/common.py b/paramiko/common.py
index 18298922..93f71df0 100644
--- a/paramiko/common.py
+++ b/paramiko/common.py
@@ -171,3 +171,14 @@ CRITICAL = logging.CRITICAL
 
 # Common IO/select/etc sleep period, in seconds
 io_sleep = 0.01
+
+DEFAULT_WINDOW_SIZE = 64 * 2 ** 15
+DEFAULT_MAX_PACKET_SIZE = 2 ** 15
+
+# lower bound on the max packet size we'll accept from the remote host
+# Minimum packet size is 32768 bytes according to
+# http://www.ietf.org/rfc/rfc4254.txt
+MIN_PACKET_SIZE = 2 ** 15
+
+# Max windows size according to http://www.ietf.org/rfc/rfc4254.txt
+MAX_WINDOW_SIZE = 2**32 -1
diff --git a/paramiko/transport.py b/paramiko/transport.py
index da67408f..fb7ab113 100644
--- a/paramiko/transport.py
+++ b/paramiko/transport.py
@@ -31,7 +31,7 @@ from hashlib import md5, sha1
 import paramiko
 from paramiko import util
 from paramiko.auth_handler import AuthHandler
-from paramiko.channel import Channel, MIN_PACKET_SIZE, MAX_WINDOW_SIZE
+from paramiko.channel import Channel
 from paramiko.common import xffffffff, cMSG_CHANNEL_OPEN, cMSG_IGNORE, \
     cMSG_GLOBAL_REQUEST, DEBUG, MSG_KEXINIT, MSG_IGNORE, MSG_DISCONNECT, \
     MSG_DEBUG, ERROR, WARNING, cMSG_UNIMPLEMENTED, INFO, cMSG_KEXINIT, \
@@ -42,7 +42,8 @@ from paramiko.common import xffffffff, cMSG_CHANNEL_OPEN, cMSG_IGNORE, \
     MSG_CHANNEL_OPEN_SUCCESS, MSG_CHANNEL_OPEN_FAILURE, MSG_CHANNEL_OPEN, \
     MSG_CHANNEL_SUCCESS, MSG_CHANNEL_FAILURE, MSG_CHANNEL_DATA, \
     MSG_CHANNEL_EXTENDED_DATA, MSG_CHANNEL_WINDOW_ADJUST, MSG_CHANNEL_REQUEST, \
-    MSG_CHANNEL_EOF, MSG_CHANNEL_CLOSE
+    MSG_CHANNEL_EOF, MSG_CHANNEL_CLOSE, MIN_PACKET_SIZE, MAX_WINDOW_SIZE, \
+    DEFAULT_WINDOW_SIZE, DEFAULT_MAX_PACKET_SIZE
 from paramiko.compress import ZlibCompressor, ZlibDecompressor
 from paramiko.dsskey import DSSKey
 from paramiko.kex_gex import KexGex
@@ -137,8 +138,8 @@ class Transport (threading.Thread):
 
     def __init__(self,
                  sock,
-                 default_window_size=64 * 2 ** 15,
-                 default_max_packet_size=2 ** 15):
+                 default_window_size=DEFAULT_WINDOW_SIZE,
+                 default_max_packet_size=DEFAULT_MAX_PACKET_SIZE):
         """
         Create a new SSH session over an existing socket, or socket-like
         object.  This only creates the `.Transport` object; it doesn't begin the