From 146417c56c3a9911b0c4f4eec212e69d2d994455 Mon Sep 17 00:00:00 2001
From: Robey Pointer <robey@lag.net>
Date: Thu, 10 Jun 2004 18:08:50 +0000
Subject: [PATCH] [project @
 Arch-1:robey@lag.net--2003-public%secsh--dev--1.0--patch-60] limit read/write
 requests to 32KB, advertise 32KB max packet size one of the unit tests was
 failing because the openssh sftp server was dropping the connection without
 any error.  turns out they have a maximum allowed write size (possibly around
 64KB).  the sftp rfcs have a small hint that some servers may drop read/write
 requests of greater than 32KB.

so, all reads are limited to 32KB, and all writes > 32KB are now chopped up
and sent in 32KB chunks.  this seems to keep openssh happy.

also, we now advertise 32KB max packet size instead of 8KB (the speed
improves a lot), and log when we read/write a packet.  and sftp files are
flushed on seek.
---
 paramiko/sftp.py      | 18 +++++++++++++++---
 paramiko/transport.py | 16 ++++++++++------
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/paramiko/sftp.py b/paramiko/sftp.py
index 0e7f48f..d5948ed 100644
--- a/paramiko/sftp.py
+++ b/paramiko/sftp.py
@@ -15,7 +15,7 @@
 # details.
 #
 # You should have received a copy of the GNU Lesser General Public License
-# along with Foobar; if not, write to the Free Software Foundation, Inc.,
+# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 import struct, socket
@@ -121,6 +121,11 @@ class SFTPError (Exception):
 
 
 class SFTPFile (BufferedFile):
+
+    # some sftp servers will choke if you send read/write requests larger than
+    # this size.
+    MAX_REQUEST_SIZE = 32768
+
     def __init__(self, sftp, handle, mode='r', bufsize=-1):
         BufferedFile.__init__(self)
         self.sftp = sftp
@@ -143,16 +148,23 @@ class SFTPFile (BufferedFile):
         self.sftp._request(CMD_CLOSE, self.handle)
 
     def _read(self, size):
+        size = min(size, self.MAX_REQUEST_SIZE)
         t, msg = self.sftp._request(CMD_READ, self.handle, long(self._realpos), int(size))
         if t != CMD_DATA:
             raise SFTPError('Expected data')
         return msg.get_string()
 
     def _write(self, data):
-        t, msg = self.sftp._request(CMD_WRITE, self.handle, long(self._realpos), str(data))
+        offset = 0
+        while offset < len(data):
+            chunk = min(len(data) - offset, self.MAX_REQUEST_SIZE)
+            t, msg = self.sftp._request(CMD_WRITE, self.handle, long(self._realpos + offset),
+                                        str(data[offset : offset + chunk]))
+            offset += chunk
         return len(data)
 
     def seek(self, offset, whence=0):
+        self.flush()
         if whence == self.SEEK_SET:
             self._realpos = self._pos = offset
         elif whence == self.SEEK_CUR:
@@ -160,7 +172,7 @@ class SFTPFile (BufferedFile):
             self._pos += offset
         else:
             self._realpos = self._pos = self._get_size() + offset
-        self._rbuffer = self._wbuffer = ''
+        self._rbuffer = ''
 
     def stat(self):
         """
diff --git a/paramiko/transport.py b/paramiko/transport.py
index ac3560c..06f7580 100644
--- a/paramiko/transport.py
+++ b/paramiko/transport.py
@@ -15,7 +15,7 @@
 # details.
 #
 # You should have received a copy of the GNU Lesser General Public License
-# along with Foobar; if not, write to the Free Software Foundation, Inc.,
+# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
@@ -162,8 +162,8 @@ class BaseTransport (threading.Thread):
         self.channel_counter = 1
         self.logger = logging.getLogger('paramiko.transport')
         self.window_size = 65536
-        self.max_packet_size = 8192
-        self.ultra_debug = 0
+        self.max_packet_size = 32768
+        self.ultra_debug = False
         self.saved_exception = None
         # used for noticing when to re-key:
         self.received_bytes = 0
@@ -792,7 +792,9 @@ class BaseTransport (threading.Thread):
     def _send_message(self, data):
         # FIXME: should we check for rekeying here too?
         # encrypt this sucka
-        packet = self._build_packet(str(data))
+        data = str(data)
+        self._log(DEBUG, 'Write packet $%x, length %d' % (ord(data[0]), len(data)))
+        packet = self._build_packet(data)
         if self.ultra_debug:
             self._log(DEBUG, util.format_binary(packet, 'OUT: '))
         if self.engine_out != None:
@@ -861,8 +863,10 @@ class BaseTransport (threading.Thread):
                 self.received_packets_overflow += 1
                 if self.received_packets_overflow >= 20:
                     raise SSHException('Remote transport is ignoring rekey requests')
-                
-        return ord(payload[0]), msg
+
+        cmd = ord(payload[0])
+        self._log(DEBUG, 'Read packet $%x, length %d' % (cmd, len(payload)))
+        return cmd, msg
 
     def _set_K_H(self, k, h):
         "used by a kex object to set the K (root key) and H (exchange hash)"