doc

git-svn-id: http://ncclient.googlecode.com/svn/trunk@49 6dbcf712-26ac-11de-a2f3-1373824ab735

diff --git a/ncclient/session/ssh.py b/ncclient/session/ssh.py
index 30a8fc2..bcba220 100644 (file)
--- a/ncclient/session/ssh.py
+++ b/ncclient/session/ssh.py
@@ -14,7 +14,7 @@
 
 from cStringIO import StringIO
 from os import SEEK_CUR
-import socket
+from select import select
 
 import paramiko
 
@@ -24,6 +24,11 @@ from session import Session, SessionError, SessionCloseError
 BUF_SIZE = 4096
 MSG_DELIM = ']]>]]>'
 
+# TODO:
+# chuck SSHClient and use paramiko low-level api to get cisco compatibility
+# and finer control over host key verification, authentication, and error
+# handling
+
 class SSHSession(Session):
 
     def __init__(self, load_known_hosts=True,
@@ -43,6 +48,10 @@ class SSHSession(Session):
         self._connected = False
     
     def _fresh_data(self):
+        '''The buffer could have grown by a maximum of BUF_SIZE bytes everytime 
+        this method is called. Retains state across method calls and if a byte
+        has been read it will not be parsed again.
+        '''
         delim = MSG_DELIM
         n = len(delim) - 1
         state = self._parsing_state
@@ -61,7 +70,7 @@ class SSHSession(Session):
                 x = buf.read(1)
                 if not x: # done reading
                     break
-                if x==delim[i]: # what we expected
+                if x==delim[state]: # what we expected
                     state += 1 # expect the next delim char
                 else:
                     state = 0 # reset
@@ -101,29 +110,30 @@ class SSHSession(Session):
         self._connected = True
         self._post_connect()
     
-    
     def run(self):
         chan = self._channel
         chan.setblocking(0)
         q = self._q
         try:
             while True:
-                if chan.closed:
-                    raise SessionCloseError(self._in_buf.getvalue())         
-                if chan.send_ready() and not q.empty():
-                    data = q.get() + MSG_DELIM
-                    while data:
-                        n = chan.send(data)
-                        if n <= 0:
-                            raise SessionCloseError(self._in_buf.getvalue(), data)
-                        data = data[n:]
-                if chan.recv_ready():
+                # select on a paramiko ssh channel object does not ever
+                # return it in the writable list, so it does not exactly
+                # emulate the socket api
+                r, w, e = select([chan], [], [], 0.1)
+                if r:
                     data = chan.recv(BUF_SIZE)
                     if data:
                         self._in_buf.write(data)
                         self._fresh_data()
                     else:
                         raise SessionCloseError(self._in_buf.getvalue())
+                if not q.empty() and chan.send_ready():
+                    data = q.get() + MSG_DELIM
+                    while data:
+                        n = chan.send(data)
+                        if n <= 0:
+                            raise SessionCloseError(self._in_buf.getvalue(), data)
+                        data = data[n:]
         except Exception as e:
             logger.debug('*** broke out of main loop ***')
             self.dispatch('error', e)